1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Kernel-based Virtual Machine driver for Linux |
4 | * |
5 | * This module enables machines with Intel VT-x extensions to run virtual |
6 | * machines without emulation or binary translation. |
7 | * |
8 | * MMU support |
9 | * |
10 | * Copyright (C) 2006 Qumranet, Inc. |
11 | * Copyright 2010 Red Hat, Inc. and/or its affiliates. |
12 | * |
13 | * Authors: |
14 | * Yaniv Kamay <yaniv@qumranet.com> |
15 | * Avi Kivity <avi@qumranet.com> |
16 | */ |
17 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
18 | |
19 | #include "irq.h" |
20 | #include "ioapic.h" |
21 | #include "mmu.h" |
22 | #include "mmu_internal.h" |
23 | #include "tdp_mmu.h" |
24 | #include "x86.h" |
25 | #include "kvm_cache_regs.h" |
26 | #include "smm.h" |
27 | #include "kvm_emulate.h" |
28 | #include "page_track.h" |
29 | #include "cpuid.h" |
30 | #include "spte.h" |
31 | |
32 | #include <linux/kvm_host.h> |
33 | #include <linux/types.h> |
34 | #include <linux/string.h> |
35 | #include <linux/mm.h> |
36 | #include <linux/highmem.h> |
37 | #include <linux/moduleparam.h> |
38 | #include <linux/export.h> |
39 | #include <linux/swap.h> |
40 | #include <linux/hugetlb.h> |
41 | #include <linux/compiler.h> |
42 | #include <linux/srcu.h> |
43 | #include <linux/slab.h> |
44 | #include <linux/sched/signal.h> |
45 | #include <linux/uaccess.h> |
46 | #include <linux/hash.h> |
47 | #include <linux/kern_levels.h> |
48 | #include <linux/kstrtox.h> |
49 | #include <linux/kthread.h> |
50 | #include <linux/wordpart.h> |
51 | |
52 | #include <asm/page.h> |
53 | #include <asm/memtype.h> |
54 | #include <asm/cmpxchg.h> |
55 | #include <asm/io.h> |
56 | #include <asm/set_memory.h> |
57 | #include <asm/spec-ctrl.h> |
58 | #include <asm/vmx.h> |
59 | |
60 | #include "trace.h" |
61 | |
62 | static bool nx_hugepage_mitigation_hard_disabled; |
63 | |
64 | int __read_mostly nx_huge_pages = -1; |
65 | static uint __read_mostly nx_huge_pages_recovery_period_ms; |
66 | #ifdef CONFIG_PREEMPT_RT |
67 | /* Recovery can cause latency spikes, disable it for PREEMPT_RT. */ |
68 | static uint __read_mostly nx_huge_pages_recovery_ratio = 0; |
69 | #else |
70 | static uint __read_mostly nx_huge_pages_recovery_ratio = 60; |
71 | #endif |
72 | |
73 | static int get_nx_huge_pages(char *buffer, const struct kernel_param *kp); |
74 | static int set_nx_huge_pages(const char *val, const struct kernel_param *kp); |
75 | static int set_nx_huge_pages_recovery_param(const char *val, const struct kernel_param *kp); |
76 | |
77 | static const struct kernel_param_ops nx_huge_pages_ops = { |
78 | .set = set_nx_huge_pages, |
79 | .get = get_nx_huge_pages, |
80 | }; |
81 | |
82 | static const struct kernel_param_ops nx_huge_pages_recovery_param_ops = { |
83 | .set = set_nx_huge_pages_recovery_param, |
84 | .get = param_get_uint, |
85 | }; |
86 | |
87 | module_param_cb(nx_huge_pages, &nx_huge_pages_ops, &nx_huge_pages, 0644); |
88 | __MODULE_PARM_TYPE(nx_huge_pages, "bool" ); |
89 | module_param_cb(nx_huge_pages_recovery_ratio, &nx_huge_pages_recovery_param_ops, |
90 | &nx_huge_pages_recovery_ratio, 0644); |
91 | __MODULE_PARM_TYPE(nx_huge_pages_recovery_ratio, "uint" ); |
92 | module_param_cb(nx_huge_pages_recovery_period_ms, &nx_huge_pages_recovery_param_ops, |
93 | &nx_huge_pages_recovery_period_ms, 0644); |
94 | __MODULE_PARM_TYPE(nx_huge_pages_recovery_period_ms, "uint" ); |
95 | |
96 | static bool __read_mostly force_flush_and_sync_on_reuse; |
97 | module_param_named(flush_on_reuse, force_flush_and_sync_on_reuse, bool, 0644); |
98 | |
99 | /* |
100 | * When setting this variable to true it enables Two-Dimensional-Paging |
101 | * where the hardware walks 2 page tables: |
102 | * 1. the guest-virtual to guest-physical |
103 | * 2. while doing 1. it walks guest-physical to host-physical |
104 | * If the hardware supports that we don't need to do shadow paging. |
105 | */ |
106 | bool tdp_enabled = false; |
107 | |
108 | static bool __ro_after_init tdp_mmu_allowed; |
109 | |
110 | #ifdef CONFIG_X86_64 |
111 | bool __read_mostly tdp_mmu_enabled = true; |
112 | module_param_named(tdp_mmu, tdp_mmu_enabled, bool, 0444); |
113 | #endif |
114 | |
115 | static int max_huge_page_level __read_mostly; |
116 | static int tdp_root_level __read_mostly; |
117 | static int max_tdp_level __read_mostly; |
118 | |
119 | #define PTE_PREFETCH_NUM 8 |
120 | |
121 | #include <trace/events/kvm.h> |
122 | |
123 | /* make pte_list_desc fit well in cache lines */ |
124 | #define PTE_LIST_EXT 14 |
125 | |
126 | /* |
127 | * struct pte_list_desc is the core data structure used to implement a custom |
128 | * list for tracking a set of related SPTEs, e.g. all the SPTEs that map a |
129 | * given GFN when used in the context of rmaps. Using a custom list allows KVM |
130 | * to optimize for the common case where many GFNs will have at most a handful |
131 | * of SPTEs pointing at them, i.e. allows packing multiple SPTEs into a small |
132 | * memory footprint, which in turn improves runtime performance by exploiting |
133 | * cache locality. |
134 | * |
135 | * A list is comprised of one or more pte_list_desc objects (descriptors). |
136 | * Each individual descriptor stores up to PTE_LIST_EXT SPTEs. If a descriptor |
137 | * is full and a new SPTEs needs to be added, a new descriptor is allocated and |
138 | * becomes the head of the list. This means that by definitions, all tail |
139 | * descriptors are full. |
140 | * |
141 | * Note, the meta data fields are deliberately placed at the start of the |
142 | * structure to optimize the cacheline layout; accessing the descriptor will |
143 | * touch only a single cacheline so long as @spte_count<=6 (or if only the |
144 | * descriptors metadata is accessed). |
145 | */ |
146 | struct pte_list_desc { |
147 | struct pte_list_desc *more; |
148 | /* The number of PTEs stored in _this_ descriptor. */ |
149 | u32 spte_count; |
150 | /* The number of PTEs stored in all tails of this descriptor. */ |
151 | u32 tail_count; |
152 | u64 *sptes[PTE_LIST_EXT]; |
153 | }; |
154 | |
155 | struct kvm_shadow_walk_iterator { |
156 | u64 addr; |
157 | hpa_t shadow_addr; |
158 | u64 *sptep; |
159 | int level; |
160 | unsigned index; |
161 | }; |
162 | |
163 | #define for_each_shadow_entry_using_root(_vcpu, _root, _addr, _walker) \ |
164 | for (shadow_walk_init_using_root(&(_walker), (_vcpu), \ |
165 | (_root), (_addr)); \ |
166 | shadow_walk_okay(&(_walker)); \ |
167 | shadow_walk_next(&(_walker))) |
168 | |
169 | #define for_each_shadow_entry(_vcpu, _addr, _walker) \ |
170 | for (shadow_walk_init(&(_walker), _vcpu, _addr); \ |
171 | shadow_walk_okay(&(_walker)); \ |
172 | shadow_walk_next(&(_walker))) |
173 | |
174 | #define for_each_shadow_entry_lockless(_vcpu, _addr, _walker, spte) \ |
175 | for (shadow_walk_init(&(_walker), _vcpu, _addr); \ |
176 | shadow_walk_okay(&(_walker)) && \ |
177 | ({ spte = mmu_spte_get_lockless(_walker.sptep); 1; }); \ |
178 | __shadow_walk_next(&(_walker), spte)) |
179 | |
180 | static struct kmem_cache *pte_list_desc_cache; |
181 | struct kmem_cache *; |
182 | static struct percpu_counter kvm_total_used_mmu_pages; |
183 | |
184 | static void mmu_spte_set(u64 *sptep, u64 spte); |
185 | |
186 | struct kvm_mmu_role_regs { |
187 | const unsigned long cr0; |
188 | const unsigned long cr4; |
189 | const u64 efer; |
190 | }; |
191 | |
192 | #define CREATE_TRACE_POINTS |
193 | #include "mmutrace.h" |
194 | |
195 | /* |
196 | * Yes, lot's of underscores. They're a hint that you probably shouldn't be |
197 | * reading from the role_regs. Once the root_role is constructed, it becomes |
198 | * the single source of truth for the MMU's state. |
199 | */ |
200 | #define BUILD_MMU_ROLE_REGS_ACCESSOR(reg, name, flag) \ |
201 | static inline bool __maybe_unused \ |
202 | ____is_##reg##_##name(const struct kvm_mmu_role_regs *regs) \ |
203 | { \ |
204 | return !!(regs->reg & flag); \ |
205 | } |
206 | BUILD_MMU_ROLE_REGS_ACCESSOR(cr0, pg, X86_CR0_PG); |
207 | BUILD_MMU_ROLE_REGS_ACCESSOR(cr0, wp, X86_CR0_WP); |
208 | BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, pse, X86_CR4_PSE); |
209 | BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, pae, X86_CR4_PAE); |
210 | BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, smep, X86_CR4_SMEP); |
211 | BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, smap, X86_CR4_SMAP); |
212 | BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, pke, X86_CR4_PKE); |
213 | BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, la57, X86_CR4_LA57); |
214 | BUILD_MMU_ROLE_REGS_ACCESSOR(efer, nx, EFER_NX); |
215 | BUILD_MMU_ROLE_REGS_ACCESSOR(efer, lma, EFER_LMA); |
216 | |
217 | /* |
218 | * The MMU itself (with a valid role) is the single source of truth for the |
219 | * MMU. Do not use the regs used to build the MMU/role, nor the vCPU. The |
220 | * regs don't account for dependencies, e.g. clearing CR4 bits if CR0.PG=1, |
221 | * and the vCPU may be incorrect/irrelevant. |
222 | */ |
223 | #define BUILD_MMU_ROLE_ACCESSOR(base_or_ext, reg, name) \ |
224 | static inline bool __maybe_unused is_##reg##_##name(struct kvm_mmu *mmu) \ |
225 | { \ |
226 | return !!(mmu->cpu_role. base_or_ext . reg##_##name); \ |
227 | } |
228 | BUILD_MMU_ROLE_ACCESSOR(base, cr0, wp); |
229 | BUILD_MMU_ROLE_ACCESSOR(ext, cr4, pse); |
230 | BUILD_MMU_ROLE_ACCESSOR(ext, cr4, smep); |
231 | BUILD_MMU_ROLE_ACCESSOR(ext, cr4, smap); |
232 | BUILD_MMU_ROLE_ACCESSOR(ext, cr4, pke); |
233 | BUILD_MMU_ROLE_ACCESSOR(ext, cr4, la57); |
234 | BUILD_MMU_ROLE_ACCESSOR(base, efer, nx); |
235 | BUILD_MMU_ROLE_ACCESSOR(ext, efer, lma); |
236 | |
237 | static inline bool is_cr0_pg(struct kvm_mmu *mmu) |
238 | { |
239 | return mmu->cpu_role.base.level > 0; |
240 | } |
241 | |
242 | static inline bool is_cr4_pae(struct kvm_mmu *mmu) |
243 | { |
244 | return !mmu->cpu_role.base.has_4_byte_gpte; |
245 | } |
246 | |
247 | static struct kvm_mmu_role_regs vcpu_to_role_regs(struct kvm_vcpu *vcpu) |
248 | { |
249 | struct kvm_mmu_role_regs regs = { |
250 | .cr0 = kvm_read_cr0_bits(vcpu, KVM_MMU_CR0_ROLE_BITS), |
251 | .cr4 = kvm_read_cr4_bits(vcpu, KVM_MMU_CR4_ROLE_BITS), |
252 | .efer = vcpu->arch.efer, |
253 | }; |
254 | |
255 | return regs; |
256 | } |
257 | |
258 | static unsigned long get_guest_cr3(struct kvm_vcpu *vcpu) |
259 | { |
260 | return kvm_read_cr3(vcpu); |
261 | } |
262 | |
263 | static inline unsigned long kvm_mmu_get_guest_pgd(struct kvm_vcpu *vcpu, |
264 | struct kvm_mmu *mmu) |
265 | { |
266 | if (IS_ENABLED(CONFIG_MITIGATION_RETPOLINE) && mmu->get_guest_pgd == get_guest_cr3) |
267 | return kvm_read_cr3(vcpu); |
268 | |
269 | return mmu->get_guest_pgd(vcpu); |
270 | } |
271 | |
272 | static inline bool kvm_available_flush_remote_tlbs_range(void) |
273 | { |
274 | #if IS_ENABLED(CONFIG_HYPERV) |
275 | return kvm_x86_ops.flush_remote_tlbs_range; |
276 | #else |
277 | return false; |
278 | #endif |
279 | } |
280 | |
281 | static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index); |
282 | |
283 | /* Flush the range of guest memory mapped by the given SPTE. */ |
284 | static void kvm_flush_remote_tlbs_sptep(struct kvm *kvm, u64 *sptep) |
285 | { |
286 | struct kvm_mmu_page *sp = sptep_to_sp(sptep); |
287 | gfn_t gfn = kvm_mmu_page_get_gfn(sp, index: spte_index(sptep)); |
288 | |
289 | kvm_flush_remote_tlbs_gfn(kvm, gfn, level: sp->role.level); |
290 | } |
291 | |
292 | static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn, |
293 | unsigned int access) |
294 | { |
295 | u64 spte = make_mmio_spte(vcpu, gfn, access); |
296 | |
297 | trace_mark_mmio_spte(sptep, gfn, spte); |
298 | mmu_spte_set(sptep, spte); |
299 | } |
300 | |
301 | static gfn_t get_mmio_spte_gfn(u64 spte) |
302 | { |
303 | u64 gpa = spte & shadow_nonpresent_or_rsvd_lower_gfn_mask; |
304 | |
305 | gpa |= (spte >> SHADOW_NONPRESENT_OR_RSVD_MASK_LEN) |
306 | & shadow_nonpresent_or_rsvd_mask; |
307 | |
308 | return gpa >> PAGE_SHIFT; |
309 | } |
310 | |
311 | static unsigned get_mmio_spte_access(u64 spte) |
312 | { |
313 | return spte & shadow_mmio_access_mask; |
314 | } |
315 | |
316 | static bool check_mmio_spte(struct kvm_vcpu *vcpu, u64 spte) |
317 | { |
318 | u64 kvm_gen, spte_gen, gen; |
319 | |
320 | gen = kvm_vcpu_memslots(vcpu)->generation; |
321 | if (unlikely(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS)) |
322 | return false; |
323 | |
324 | kvm_gen = gen & MMIO_SPTE_GEN_MASK; |
325 | spte_gen = get_mmio_spte_generation(spte); |
326 | |
327 | trace_check_mmio_spte(spte, kvm_gen, spte_gen); |
328 | return likely(kvm_gen == spte_gen); |
329 | } |
330 | |
331 | static int is_cpuid_PSE36(void) |
332 | { |
333 | return 1; |
334 | } |
335 | |
336 | #ifdef CONFIG_X86_64 |
337 | static void __set_spte(u64 *sptep, u64 spte) |
338 | { |
339 | WRITE_ONCE(*sptep, spte); |
340 | } |
341 | |
342 | static void __update_clear_spte_fast(u64 *sptep, u64 spte) |
343 | { |
344 | WRITE_ONCE(*sptep, spte); |
345 | } |
346 | |
347 | static u64 __update_clear_spte_slow(u64 *sptep, u64 spte) |
348 | { |
349 | return xchg(sptep, spte); |
350 | } |
351 | |
352 | static u64 __get_spte_lockless(u64 *sptep) |
353 | { |
354 | return READ_ONCE(*sptep); |
355 | } |
356 | #else |
357 | union split_spte { |
358 | struct { |
359 | u32 spte_low; |
360 | u32 spte_high; |
361 | }; |
362 | u64 spte; |
363 | }; |
364 | |
365 | static void count_spte_clear(u64 *sptep, u64 spte) |
366 | { |
367 | struct kvm_mmu_page *sp = sptep_to_sp(sptep); |
368 | |
369 | if (is_shadow_present_pte(spte)) |
370 | return; |
371 | |
372 | /* Ensure the spte is completely set before we increase the count */ |
373 | smp_wmb(); |
374 | sp->clear_spte_count++; |
375 | } |
376 | |
377 | static void __set_spte(u64 *sptep, u64 spte) |
378 | { |
379 | union split_spte *ssptep, sspte; |
380 | |
381 | ssptep = (union split_spte *)sptep; |
382 | sspte = (union split_spte)spte; |
383 | |
384 | ssptep->spte_high = sspte.spte_high; |
385 | |
386 | /* |
387 | * If we map the spte from nonpresent to present, We should store |
388 | * the high bits firstly, then set present bit, so cpu can not |
389 | * fetch this spte while we are setting the spte. |
390 | */ |
391 | smp_wmb(); |
392 | |
393 | WRITE_ONCE(ssptep->spte_low, sspte.spte_low); |
394 | } |
395 | |
396 | static void __update_clear_spte_fast(u64 *sptep, u64 spte) |
397 | { |
398 | union split_spte *ssptep, sspte; |
399 | |
400 | ssptep = (union split_spte *)sptep; |
401 | sspte = (union split_spte)spte; |
402 | |
403 | WRITE_ONCE(ssptep->spte_low, sspte.spte_low); |
404 | |
405 | /* |
406 | * If we map the spte from present to nonpresent, we should clear |
407 | * present bit firstly to avoid vcpu fetch the old high bits. |
408 | */ |
409 | smp_wmb(); |
410 | |
411 | ssptep->spte_high = sspte.spte_high; |
412 | count_spte_clear(sptep, spte); |
413 | } |
414 | |
415 | static u64 __update_clear_spte_slow(u64 *sptep, u64 spte) |
416 | { |
417 | union split_spte *ssptep, sspte, orig; |
418 | |
419 | ssptep = (union split_spte *)sptep; |
420 | sspte = (union split_spte)spte; |
421 | |
422 | /* xchg acts as a barrier before the setting of the high bits */ |
423 | orig.spte_low = xchg(&ssptep->spte_low, sspte.spte_low); |
424 | orig.spte_high = ssptep->spte_high; |
425 | ssptep->spte_high = sspte.spte_high; |
426 | count_spte_clear(sptep, spte); |
427 | |
428 | return orig.spte; |
429 | } |
430 | |
431 | /* |
432 | * The idea using the light way get the spte on x86_32 guest is from |
433 | * gup_get_pte (mm/gup.c). |
434 | * |
435 | * An spte tlb flush may be pending, because kvm_set_pte_rmap |
436 | * coalesces them and we are running out of the MMU lock. Therefore |
437 | * we need to protect against in-progress updates of the spte. |
438 | * |
439 | * Reading the spte while an update is in progress may get the old value |
440 | * for the high part of the spte. The race is fine for a present->non-present |
441 | * change (because the high part of the spte is ignored for non-present spte), |
442 | * but for a present->present change we must reread the spte. |
443 | * |
444 | * All such changes are done in two steps (present->non-present and |
445 | * non-present->present), hence it is enough to count the number of |
446 | * present->non-present updates: if it changed while reading the spte, |
447 | * we might have hit the race. This is done using clear_spte_count. |
448 | */ |
449 | static u64 __get_spte_lockless(u64 *sptep) |
450 | { |
451 | struct kvm_mmu_page *sp = sptep_to_sp(sptep); |
452 | union split_spte spte, *orig = (union split_spte *)sptep; |
453 | int count; |
454 | |
455 | retry: |
456 | count = sp->clear_spte_count; |
457 | smp_rmb(); |
458 | |
459 | spte.spte_low = orig->spte_low; |
460 | smp_rmb(); |
461 | |
462 | spte.spte_high = orig->spte_high; |
463 | smp_rmb(); |
464 | |
465 | if (unlikely(spte.spte_low != orig->spte_low || |
466 | count != sp->clear_spte_count)) |
467 | goto retry; |
468 | |
469 | return spte.spte; |
470 | } |
471 | #endif |
472 | |
473 | /* Rules for using mmu_spte_set: |
474 | * Set the sptep from nonpresent to present. |
475 | * Note: the sptep being assigned *must* be either not present |
476 | * or in a state where the hardware will not attempt to update |
477 | * the spte. |
478 | */ |
479 | static void mmu_spte_set(u64 *sptep, u64 new_spte) |
480 | { |
481 | WARN_ON_ONCE(is_shadow_present_pte(*sptep)); |
482 | __set_spte(sptep, spte: new_spte); |
483 | } |
484 | |
485 | /* |
486 | * Update the SPTE (excluding the PFN), but do not track changes in its |
487 | * accessed/dirty status. |
488 | */ |
489 | static u64 mmu_spte_update_no_track(u64 *sptep, u64 new_spte) |
490 | { |
491 | u64 old_spte = *sptep; |
492 | |
493 | WARN_ON_ONCE(!is_shadow_present_pte(new_spte)); |
494 | check_spte_writable_invariants(spte: new_spte); |
495 | |
496 | if (!is_shadow_present_pte(pte: old_spte)) { |
497 | mmu_spte_set(sptep, new_spte); |
498 | return old_spte; |
499 | } |
500 | |
501 | if (!spte_has_volatile_bits(spte: old_spte)) |
502 | __update_clear_spte_fast(sptep, spte: new_spte); |
503 | else |
504 | old_spte = __update_clear_spte_slow(sptep, spte: new_spte); |
505 | |
506 | WARN_ON_ONCE(spte_to_pfn(old_spte) != spte_to_pfn(new_spte)); |
507 | |
508 | return old_spte; |
509 | } |
510 | |
511 | /* Rules for using mmu_spte_update: |
512 | * Update the state bits, it means the mapped pfn is not changed. |
513 | * |
514 | * Whenever an MMU-writable SPTE is overwritten with a read-only SPTE, remote |
515 | * TLBs must be flushed. Otherwise rmap_write_protect will find a read-only |
516 | * spte, even though the writable spte might be cached on a CPU's TLB. |
517 | * |
518 | * Returns true if the TLB needs to be flushed |
519 | */ |
520 | static bool mmu_spte_update(u64 *sptep, u64 new_spte) |
521 | { |
522 | bool flush = false; |
523 | u64 old_spte = mmu_spte_update_no_track(sptep, new_spte); |
524 | |
525 | if (!is_shadow_present_pte(pte: old_spte)) |
526 | return false; |
527 | |
528 | /* |
529 | * For the spte updated out of mmu-lock is safe, since |
530 | * we always atomically update it, see the comments in |
531 | * spte_has_volatile_bits(). |
532 | */ |
533 | if (is_mmu_writable_spte(spte: old_spte) && |
534 | !is_writable_pte(pte: new_spte)) |
535 | flush = true; |
536 | |
537 | /* |
538 | * Flush TLB when accessed/dirty states are changed in the page tables, |
539 | * to guarantee consistency between TLB and page tables. |
540 | */ |
541 | |
542 | if (is_accessed_spte(spte: old_spte) && !is_accessed_spte(spte: new_spte)) { |
543 | flush = true; |
544 | kvm_set_pfn_accessed(pfn: spte_to_pfn(pte: old_spte)); |
545 | } |
546 | |
547 | if (is_dirty_spte(spte: old_spte) && !is_dirty_spte(spte: new_spte)) { |
548 | flush = true; |
549 | kvm_set_pfn_dirty(pfn: spte_to_pfn(pte: old_spte)); |
550 | } |
551 | |
552 | return flush; |
553 | } |
554 | |
555 | /* |
556 | * Rules for using mmu_spte_clear_track_bits: |
557 | * It sets the sptep from present to nonpresent, and track the |
558 | * state bits, it is used to clear the last level sptep. |
559 | * Returns the old PTE. |
560 | */ |
561 | static u64 mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep) |
562 | { |
563 | kvm_pfn_t pfn; |
564 | u64 old_spte = *sptep; |
565 | int level = sptep_to_sp(sptep)->role.level; |
566 | struct page *page; |
567 | |
568 | if (!is_shadow_present_pte(pte: old_spte) || |
569 | !spte_has_volatile_bits(spte: old_spte)) |
570 | __update_clear_spte_fast(sptep, spte: 0ull); |
571 | else |
572 | old_spte = __update_clear_spte_slow(sptep, spte: 0ull); |
573 | |
574 | if (!is_shadow_present_pte(pte: old_spte)) |
575 | return old_spte; |
576 | |
577 | kvm_update_page_stats(kvm, level, -1); |
578 | |
579 | pfn = spte_to_pfn(pte: old_spte); |
580 | |
581 | /* |
582 | * KVM doesn't hold a reference to any pages mapped into the guest, and |
583 | * instead uses the mmu_notifier to ensure that KVM unmaps any pages |
584 | * before they are reclaimed. Sanity check that, if the pfn is backed |
585 | * by a refcounted page, the refcount is elevated. |
586 | */ |
587 | page = kvm_pfn_to_refcounted_page(pfn); |
588 | WARN_ON_ONCE(page && !page_count(page)); |
589 | |
590 | if (is_accessed_spte(spte: old_spte)) |
591 | kvm_set_pfn_accessed(pfn); |
592 | |
593 | if (is_dirty_spte(spte: old_spte)) |
594 | kvm_set_pfn_dirty(pfn); |
595 | |
596 | return old_spte; |
597 | } |
598 | |
599 | /* |
600 | * Rules for using mmu_spte_clear_no_track: |
601 | * Directly clear spte without caring the state bits of sptep, |
602 | * it is used to set the upper level spte. |
603 | */ |
604 | static void mmu_spte_clear_no_track(u64 *sptep) |
605 | { |
606 | __update_clear_spte_fast(sptep, spte: 0ull); |
607 | } |
608 | |
609 | static u64 mmu_spte_get_lockless(u64 *sptep) |
610 | { |
611 | return __get_spte_lockless(sptep); |
612 | } |
613 | |
614 | /* Returns the Accessed status of the PTE and resets it at the same time. */ |
615 | static bool mmu_spte_age(u64 *sptep) |
616 | { |
617 | u64 spte = mmu_spte_get_lockless(sptep); |
618 | |
619 | if (!is_accessed_spte(spte)) |
620 | return false; |
621 | |
622 | if (spte_ad_enabled(spte)) { |
623 | clear_bit(nr: (ffs(shadow_accessed_mask) - 1), |
624 | addr: (unsigned long *)sptep); |
625 | } else { |
626 | /* |
627 | * Capture the dirty status of the page, so that it doesn't get |
628 | * lost when the SPTE is marked for access tracking. |
629 | */ |
630 | if (is_writable_pte(pte: spte)) |
631 | kvm_set_pfn_dirty(pfn: spte_to_pfn(pte: spte)); |
632 | |
633 | spte = mark_spte_for_access_track(spte); |
634 | mmu_spte_update_no_track(sptep, new_spte: spte); |
635 | } |
636 | |
637 | return true; |
638 | } |
639 | |
640 | static inline bool is_tdp_mmu_active(struct kvm_vcpu *vcpu) |
641 | { |
642 | return tdp_mmu_enabled && vcpu->arch.mmu->root_role.direct; |
643 | } |
644 | |
645 | static void walk_shadow_page_lockless_begin(struct kvm_vcpu *vcpu) |
646 | { |
647 | if (is_tdp_mmu_active(vcpu)) { |
648 | kvm_tdp_mmu_walk_lockless_begin(); |
649 | } else { |
650 | /* |
651 | * Prevent page table teardown by making any free-er wait during |
652 | * kvm_flush_remote_tlbs() IPI to all active vcpus. |
653 | */ |
654 | local_irq_disable(); |
655 | |
656 | /* |
657 | * Make sure a following spte read is not reordered ahead of the write |
658 | * to vcpu->mode. |
659 | */ |
660 | smp_store_mb(vcpu->mode, READING_SHADOW_PAGE_TABLES); |
661 | } |
662 | } |
663 | |
664 | static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu) |
665 | { |
666 | if (is_tdp_mmu_active(vcpu)) { |
667 | kvm_tdp_mmu_walk_lockless_end(); |
668 | } else { |
669 | /* |
670 | * Make sure the write to vcpu->mode is not reordered in front of |
671 | * reads to sptes. If it does, kvm_mmu_commit_zap_page() can see us |
672 | * OUTSIDE_GUEST_MODE and proceed to free the shadow page table. |
673 | */ |
674 | smp_store_release(&vcpu->mode, OUTSIDE_GUEST_MODE); |
675 | local_irq_enable(); |
676 | } |
677 | } |
678 | |
679 | static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect) |
680 | { |
681 | int r; |
682 | |
683 | /* 1 rmap, 1 parent PTE per level, and the prefetched rmaps. */ |
684 | r = kvm_mmu_topup_memory_cache(mc: &vcpu->arch.mmu_pte_list_desc_cache, |
685 | min: 1 + PT64_ROOT_MAX_LEVEL + PTE_PREFETCH_NUM); |
686 | if (r) |
687 | return r; |
688 | r = kvm_mmu_topup_memory_cache(mc: &vcpu->arch.mmu_shadow_page_cache, |
689 | PT64_ROOT_MAX_LEVEL); |
690 | if (r) |
691 | return r; |
692 | if (maybe_indirect) { |
693 | r = kvm_mmu_topup_memory_cache(mc: &vcpu->arch.mmu_shadowed_info_cache, |
694 | PT64_ROOT_MAX_LEVEL); |
695 | if (r) |
696 | return r; |
697 | } |
698 | return kvm_mmu_topup_memory_cache(mc: &vcpu->arch.mmu_page_header_cache, |
699 | PT64_ROOT_MAX_LEVEL); |
700 | } |
701 | |
702 | static void mmu_free_memory_caches(struct kvm_vcpu *vcpu) |
703 | { |
704 | kvm_mmu_free_memory_cache(mc: &vcpu->arch.mmu_pte_list_desc_cache); |
705 | kvm_mmu_free_memory_cache(mc: &vcpu->arch.mmu_shadow_page_cache); |
706 | kvm_mmu_free_memory_cache(mc: &vcpu->arch.mmu_shadowed_info_cache); |
707 | kvm_mmu_free_memory_cache(mc: &vcpu->arch.mmu_page_header_cache); |
708 | } |
709 | |
710 | static void mmu_free_pte_list_desc(struct pte_list_desc *pte_list_desc) |
711 | { |
712 | kmem_cache_free(s: pte_list_desc_cache, objp: pte_list_desc); |
713 | } |
714 | |
715 | static bool sp_has_gptes(struct kvm_mmu_page *sp); |
716 | |
717 | static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index) |
718 | { |
719 | if (sp->role.passthrough) |
720 | return sp->gfn; |
721 | |
722 | if (!sp->role.direct) |
723 | return sp->shadowed_translation[index] >> PAGE_SHIFT; |
724 | |
725 | return sp->gfn + (index << ((sp->role.level - 1) * SPTE_LEVEL_BITS)); |
726 | } |
727 | |
728 | /* |
729 | * For leaf SPTEs, fetch the *guest* access permissions being shadowed. Note |
730 | * that the SPTE itself may have a more constrained access permissions that |
731 | * what the guest enforces. For example, a guest may create an executable |
732 | * huge PTE but KVM may disallow execution to mitigate iTLB multihit. |
733 | */ |
734 | static u32 kvm_mmu_page_get_access(struct kvm_mmu_page *sp, int index) |
735 | { |
736 | if (sp_has_gptes(sp)) |
737 | return sp->shadowed_translation[index] & ACC_ALL; |
738 | |
739 | /* |
740 | * For direct MMUs (e.g. TDP or non-paging guests) or passthrough SPs, |
741 | * KVM is not shadowing any guest page tables, so the "guest access |
742 | * permissions" are just ACC_ALL. |
743 | * |
744 | * For direct SPs in indirect MMUs (shadow paging), i.e. when KVM |
745 | * is shadowing a guest huge page with small pages, the guest access |
746 | * permissions being shadowed are the access permissions of the huge |
747 | * page. |
748 | * |
749 | * In both cases, sp->role.access contains the correct access bits. |
750 | */ |
751 | return sp->role.access; |
752 | } |
753 | |
754 | static void kvm_mmu_page_set_translation(struct kvm_mmu_page *sp, int index, |
755 | gfn_t gfn, unsigned int access) |
756 | { |
757 | if (sp_has_gptes(sp)) { |
758 | sp->shadowed_translation[index] = (gfn << PAGE_SHIFT) | access; |
759 | return; |
760 | } |
761 | |
762 | WARN_ONCE(access != kvm_mmu_page_get_access(sp, index), |
763 | "access mismatch under %s page %llx (expected %u, got %u)\n" , |
764 | sp->role.passthrough ? "passthrough" : "direct" , |
765 | sp->gfn, kvm_mmu_page_get_access(sp, index), access); |
766 | |
767 | WARN_ONCE(gfn != kvm_mmu_page_get_gfn(sp, index), |
768 | "gfn mismatch under %s page %llx (expected %llx, got %llx)\n" , |
769 | sp->role.passthrough ? "passthrough" : "direct" , |
770 | sp->gfn, kvm_mmu_page_get_gfn(sp, index), gfn); |
771 | } |
772 | |
773 | static void kvm_mmu_page_set_access(struct kvm_mmu_page *sp, int index, |
774 | unsigned int access) |
775 | { |
776 | gfn_t gfn = kvm_mmu_page_get_gfn(sp, index); |
777 | |
778 | kvm_mmu_page_set_translation(sp, index, gfn, access); |
779 | } |
780 | |
781 | /* |
782 | * Return the pointer to the large page information for a given gfn, |
783 | * handling slots that are not large page aligned. |
784 | */ |
785 | static struct kvm_lpage_info *lpage_info_slot(gfn_t gfn, |
786 | const struct kvm_memory_slot *slot, int level) |
787 | { |
788 | unsigned long idx; |
789 | |
790 | idx = gfn_to_index(gfn, slot->base_gfn, level); |
791 | return &slot->arch.lpage_info[level - 2][idx]; |
792 | } |
793 | |
794 | /* |
795 | * The most significant bit in disallow_lpage tracks whether or not memory |
796 | * attributes are mixed, i.e. not identical for all gfns at the current level. |
797 | * The lower order bits are used to refcount other cases where a hugepage is |
798 | * disallowed, e.g. if KVM has shadow a page table at the gfn. |
799 | */ |
800 | #define KVM_LPAGE_MIXED_FLAG BIT(31) |
801 | |
802 | static void update_gfn_disallow_lpage_count(const struct kvm_memory_slot *slot, |
803 | gfn_t gfn, int count) |
804 | { |
805 | struct kvm_lpage_info *linfo; |
806 | int old, i; |
807 | |
808 | for (i = PG_LEVEL_2M; i <= KVM_MAX_HUGEPAGE_LEVEL; ++i) { |
809 | linfo = lpage_info_slot(gfn, slot, level: i); |
810 | |
811 | old = linfo->disallow_lpage; |
812 | linfo->disallow_lpage += count; |
813 | WARN_ON_ONCE((old ^ linfo->disallow_lpage) & KVM_LPAGE_MIXED_FLAG); |
814 | } |
815 | } |
816 | |
817 | void kvm_mmu_gfn_disallow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn) |
818 | { |
819 | update_gfn_disallow_lpage_count(slot, gfn, count: 1); |
820 | } |
821 | |
822 | void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn) |
823 | { |
824 | update_gfn_disallow_lpage_count(slot, gfn, count: -1); |
825 | } |
826 | |
827 | static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) |
828 | { |
829 | struct kvm_memslots *slots; |
830 | struct kvm_memory_slot *slot; |
831 | gfn_t gfn; |
832 | |
833 | kvm->arch.indirect_shadow_pages++; |
834 | gfn = sp->gfn; |
835 | slots = kvm_memslots_for_spte_role(kvm, sp->role); |
836 | slot = __gfn_to_memslot(slots, gfn); |
837 | |
838 | /* the non-leaf shadow pages are keeping readonly. */ |
839 | if (sp->role.level > PG_LEVEL_4K) |
840 | return __kvm_write_track_add_gfn(kvm, slot, gfn); |
841 | |
842 | kvm_mmu_gfn_disallow_lpage(slot, gfn); |
843 | |
844 | if (kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn, min_level: PG_LEVEL_4K)) |
845 | kvm_flush_remote_tlbs_gfn(kvm, gfn, level: PG_LEVEL_4K); |
846 | } |
847 | |
848 | void track_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp) |
849 | { |
850 | /* |
851 | * If it's possible to replace the shadow page with an NX huge page, |
852 | * i.e. if the shadow page is the only thing currently preventing KVM |
853 | * from using a huge page, add the shadow page to the list of "to be |
854 | * zapped for NX recovery" pages. Note, the shadow page can already be |
855 | * on the list if KVM is reusing an existing shadow page, i.e. if KVM |
856 | * links a shadow page at multiple points. |
857 | */ |
858 | if (!list_empty(head: &sp->possible_nx_huge_page_link)) |
859 | return; |
860 | |
861 | ++kvm->stat.nx_lpage_splits; |
862 | list_add_tail(new: &sp->possible_nx_huge_page_link, |
863 | head: &kvm->arch.possible_nx_huge_pages); |
864 | } |
865 | |
866 | static void account_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp, |
867 | bool nx_huge_page_possible) |
868 | { |
869 | sp->nx_huge_page_disallowed = true; |
870 | |
871 | if (nx_huge_page_possible) |
872 | track_possible_nx_huge_page(kvm, sp); |
873 | } |
874 | |
875 | static void unaccount_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) |
876 | { |
877 | struct kvm_memslots *slots; |
878 | struct kvm_memory_slot *slot; |
879 | gfn_t gfn; |
880 | |
881 | kvm->arch.indirect_shadow_pages--; |
882 | gfn = sp->gfn; |
883 | slots = kvm_memslots_for_spte_role(kvm, sp->role); |
884 | slot = __gfn_to_memslot(slots, gfn); |
885 | if (sp->role.level > PG_LEVEL_4K) |
886 | return __kvm_write_track_remove_gfn(kvm, slot, gfn); |
887 | |
888 | kvm_mmu_gfn_allow_lpage(slot, gfn); |
889 | } |
890 | |
891 | void untrack_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp) |
892 | { |
893 | if (list_empty(head: &sp->possible_nx_huge_page_link)) |
894 | return; |
895 | |
896 | --kvm->stat.nx_lpage_splits; |
897 | list_del_init(entry: &sp->possible_nx_huge_page_link); |
898 | } |
899 | |
900 | static void unaccount_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp) |
901 | { |
902 | sp->nx_huge_page_disallowed = false; |
903 | |
904 | untrack_possible_nx_huge_page(kvm, sp); |
905 | } |
906 | |
907 | static struct kvm_memory_slot *gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, |
908 | gfn_t gfn, |
909 | bool no_dirty_log) |
910 | { |
911 | struct kvm_memory_slot *slot; |
912 | |
913 | slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); |
914 | if (!slot || slot->flags & KVM_MEMSLOT_INVALID) |
915 | return NULL; |
916 | if (no_dirty_log && kvm_slot_dirty_track_enabled(slot)) |
917 | return NULL; |
918 | |
919 | return slot; |
920 | } |
921 | |
922 | /* |
923 | * About rmap_head encoding: |
924 | * |
925 | * If the bit zero of rmap_head->val is clear, then it points to the only spte |
926 | * in this rmap chain. Otherwise, (rmap_head->val & ~1) points to a struct |
927 | * pte_list_desc containing more mappings. |
928 | */ |
929 | |
930 | /* |
931 | * Returns the number of pointers in the rmap chain, not counting the new one. |
932 | */ |
933 | static int pte_list_add(struct kvm_mmu_memory_cache *cache, u64 *spte, |
934 | struct kvm_rmap_head *rmap_head) |
935 | { |
936 | struct pte_list_desc *desc; |
937 | int count = 0; |
938 | |
939 | if (!rmap_head->val) { |
940 | rmap_head->val = (unsigned long)spte; |
941 | } else if (!(rmap_head->val & 1)) { |
942 | desc = kvm_mmu_memory_cache_alloc(mc: cache); |
943 | desc->sptes[0] = (u64 *)rmap_head->val; |
944 | desc->sptes[1] = spte; |
945 | desc->spte_count = 2; |
946 | desc->tail_count = 0; |
947 | rmap_head->val = (unsigned long)desc | 1; |
948 | ++count; |
949 | } else { |
950 | desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); |
951 | count = desc->tail_count + desc->spte_count; |
952 | |
953 | /* |
954 | * If the previous head is full, allocate a new head descriptor |
955 | * as tail descriptors are always kept full. |
956 | */ |
957 | if (desc->spte_count == PTE_LIST_EXT) { |
958 | desc = kvm_mmu_memory_cache_alloc(mc: cache); |
959 | desc->more = (struct pte_list_desc *)(rmap_head->val & ~1ul); |
960 | desc->spte_count = 0; |
961 | desc->tail_count = count; |
962 | rmap_head->val = (unsigned long)desc | 1; |
963 | } |
964 | desc->sptes[desc->spte_count++] = spte; |
965 | } |
966 | return count; |
967 | } |
968 | |
969 | static void pte_list_desc_remove_entry(struct kvm *kvm, |
970 | struct kvm_rmap_head *rmap_head, |
971 | struct pte_list_desc *desc, int i) |
972 | { |
973 | struct pte_list_desc *head_desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); |
974 | int j = head_desc->spte_count - 1; |
975 | |
976 | /* |
977 | * The head descriptor should never be empty. A new head is added only |
978 | * when adding an entry and the previous head is full, and heads are |
979 | * removed (this flow) when they become empty. |
980 | */ |
981 | KVM_BUG_ON_DATA_CORRUPTION(j < 0, kvm); |
982 | |
983 | /* |
984 | * Replace the to-be-freed SPTE with the last valid entry from the head |
985 | * descriptor to ensure that tail descriptors are full at all times. |
986 | * Note, this also means that tail_count is stable for each descriptor. |
987 | */ |
988 | desc->sptes[i] = head_desc->sptes[j]; |
989 | head_desc->sptes[j] = NULL; |
990 | head_desc->spte_count--; |
991 | if (head_desc->spte_count) |
992 | return; |
993 | |
994 | /* |
995 | * The head descriptor is empty. If there are no tail descriptors, |
996 | * nullify the rmap head to mark the list as empty, else point the rmap |
997 | * head at the next descriptor, i.e. the new head. |
998 | */ |
999 | if (!head_desc->more) |
1000 | rmap_head->val = 0; |
1001 | else |
1002 | rmap_head->val = (unsigned long)head_desc->more | 1; |
1003 | mmu_free_pte_list_desc(pte_list_desc: head_desc); |
1004 | } |
1005 | |
1006 | static void pte_list_remove(struct kvm *kvm, u64 *spte, |
1007 | struct kvm_rmap_head *rmap_head) |
1008 | { |
1009 | struct pte_list_desc *desc; |
1010 | int i; |
1011 | |
1012 | if (KVM_BUG_ON_DATA_CORRUPTION(!rmap_head->val, kvm)) |
1013 | return; |
1014 | |
1015 | if (!(rmap_head->val & 1)) { |
1016 | if (KVM_BUG_ON_DATA_CORRUPTION((u64 *)rmap_head->val != spte, kvm)) |
1017 | return; |
1018 | |
1019 | rmap_head->val = 0; |
1020 | } else { |
1021 | desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); |
1022 | while (desc) { |
1023 | for (i = 0; i < desc->spte_count; ++i) { |
1024 | if (desc->sptes[i] == spte) { |
1025 | pte_list_desc_remove_entry(kvm, rmap_head, |
1026 | desc, i); |
1027 | return; |
1028 | } |
1029 | } |
1030 | desc = desc->more; |
1031 | } |
1032 | |
1033 | KVM_BUG_ON_DATA_CORRUPTION(true, kvm); |
1034 | } |
1035 | } |
1036 | |
1037 | static void kvm_zap_one_rmap_spte(struct kvm *kvm, |
1038 | struct kvm_rmap_head *rmap_head, u64 *sptep) |
1039 | { |
1040 | mmu_spte_clear_track_bits(kvm, sptep); |
1041 | pte_list_remove(kvm, spte: sptep, rmap_head); |
1042 | } |
1043 | |
1044 | /* Return true if at least one SPTE was zapped, false otherwise */ |
1045 | static bool kvm_zap_all_rmap_sptes(struct kvm *kvm, |
1046 | struct kvm_rmap_head *rmap_head) |
1047 | { |
1048 | struct pte_list_desc *desc, *next; |
1049 | int i; |
1050 | |
1051 | if (!rmap_head->val) |
1052 | return false; |
1053 | |
1054 | if (!(rmap_head->val & 1)) { |
1055 | mmu_spte_clear_track_bits(kvm, sptep: (u64 *)rmap_head->val); |
1056 | goto out; |
1057 | } |
1058 | |
1059 | desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); |
1060 | |
1061 | for (; desc; desc = next) { |
1062 | for (i = 0; i < desc->spte_count; i++) |
1063 | mmu_spte_clear_track_bits(kvm, sptep: desc->sptes[i]); |
1064 | next = desc->more; |
1065 | mmu_free_pte_list_desc(pte_list_desc: desc); |
1066 | } |
1067 | out: |
1068 | /* rmap_head is meaningless now, remember to reset it */ |
1069 | rmap_head->val = 0; |
1070 | return true; |
1071 | } |
1072 | |
1073 | unsigned int pte_list_count(struct kvm_rmap_head *rmap_head) |
1074 | { |
1075 | struct pte_list_desc *desc; |
1076 | |
1077 | if (!rmap_head->val) |
1078 | return 0; |
1079 | else if (!(rmap_head->val & 1)) |
1080 | return 1; |
1081 | |
1082 | desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); |
1083 | return desc->tail_count + desc->spte_count; |
1084 | } |
1085 | |
1086 | static struct kvm_rmap_head *gfn_to_rmap(gfn_t gfn, int level, |
1087 | const struct kvm_memory_slot *slot) |
1088 | { |
1089 | unsigned long idx; |
1090 | |
1091 | idx = gfn_to_index(gfn, slot->base_gfn, level); |
1092 | return &slot->arch.rmap[level - PG_LEVEL_4K][idx]; |
1093 | } |
1094 | |
1095 | static void rmap_remove(struct kvm *kvm, u64 *spte) |
1096 | { |
1097 | struct kvm_memslots *slots; |
1098 | struct kvm_memory_slot *slot; |
1099 | struct kvm_mmu_page *sp; |
1100 | gfn_t gfn; |
1101 | struct kvm_rmap_head *rmap_head; |
1102 | |
1103 | sp = sptep_to_sp(sptep: spte); |
1104 | gfn = kvm_mmu_page_get_gfn(sp, index: spte_index(sptep: spte)); |
1105 | |
1106 | /* |
1107 | * Unlike rmap_add, rmap_remove does not run in the context of a vCPU |
1108 | * so we have to determine which memslots to use based on context |
1109 | * information in sp->role. |
1110 | */ |
1111 | slots = kvm_memslots_for_spte_role(kvm, sp->role); |
1112 | |
1113 | slot = __gfn_to_memslot(slots, gfn); |
1114 | rmap_head = gfn_to_rmap(gfn, level: sp->role.level, slot); |
1115 | |
1116 | pte_list_remove(kvm, spte, rmap_head); |
1117 | } |
1118 | |
1119 | /* |
1120 | * Used by the following functions to iterate through the sptes linked by a |
1121 | * rmap. All fields are private and not assumed to be used outside. |
1122 | */ |
1123 | struct rmap_iterator { |
1124 | /* private fields */ |
1125 | struct pte_list_desc *desc; /* holds the sptep if not NULL */ |
1126 | int pos; /* index of the sptep */ |
1127 | }; |
1128 | |
1129 | /* |
1130 | * Iteration must be started by this function. This should also be used after |
1131 | * removing/dropping sptes from the rmap link because in such cases the |
1132 | * information in the iterator may not be valid. |
1133 | * |
1134 | * Returns sptep if found, NULL otherwise. |
1135 | */ |
1136 | static u64 *rmap_get_first(struct kvm_rmap_head *rmap_head, |
1137 | struct rmap_iterator *iter) |
1138 | { |
1139 | u64 *sptep; |
1140 | |
1141 | if (!rmap_head->val) |
1142 | return NULL; |
1143 | |
1144 | if (!(rmap_head->val & 1)) { |
1145 | iter->desc = NULL; |
1146 | sptep = (u64 *)rmap_head->val; |
1147 | goto out; |
1148 | } |
1149 | |
1150 | iter->desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); |
1151 | iter->pos = 0; |
1152 | sptep = iter->desc->sptes[iter->pos]; |
1153 | out: |
1154 | BUG_ON(!is_shadow_present_pte(*sptep)); |
1155 | return sptep; |
1156 | } |
1157 | |
1158 | /* |
1159 | * Must be used with a valid iterator: e.g. after rmap_get_first(). |
1160 | * |
1161 | * Returns sptep if found, NULL otherwise. |
1162 | */ |
1163 | static u64 *rmap_get_next(struct rmap_iterator *iter) |
1164 | { |
1165 | u64 *sptep; |
1166 | |
1167 | if (iter->desc) { |
1168 | if (iter->pos < PTE_LIST_EXT - 1) { |
1169 | ++iter->pos; |
1170 | sptep = iter->desc->sptes[iter->pos]; |
1171 | if (sptep) |
1172 | goto out; |
1173 | } |
1174 | |
1175 | iter->desc = iter->desc->more; |
1176 | |
1177 | if (iter->desc) { |
1178 | iter->pos = 0; |
1179 | /* desc->sptes[0] cannot be NULL */ |
1180 | sptep = iter->desc->sptes[iter->pos]; |
1181 | goto out; |
1182 | } |
1183 | } |
1184 | |
1185 | return NULL; |
1186 | out: |
1187 | BUG_ON(!is_shadow_present_pte(*sptep)); |
1188 | return sptep; |
1189 | } |
1190 | |
1191 | #define for_each_rmap_spte(_rmap_head_, _iter_, _spte_) \ |
1192 | for (_spte_ = rmap_get_first(_rmap_head_, _iter_); \ |
1193 | _spte_; _spte_ = rmap_get_next(_iter_)) |
1194 | |
1195 | static void drop_spte(struct kvm *kvm, u64 *sptep) |
1196 | { |
1197 | u64 old_spte = mmu_spte_clear_track_bits(kvm, sptep); |
1198 | |
1199 | if (is_shadow_present_pte(pte: old_spte)) |
1200 | rmap_remove(kvm, spte: sptep); |
1201 | } |
1202 | |
1203 | static void drop_large_spte(struct kvm *kvm, u64 *sptep, bool flush) |
1204 | { |
1205 | struct kvm_mmu_page *sp; |
1206 | |
1207 | sp = sptep_to_sp(sptep); |
1208 | WARN_ON_ONCE(sp->role.level == PG_LEVEL_4K); |
1209 | |
1210 | drop_spte(kvm, sptep); |
1211 | |
1212 | if (flush) |
1213 | kvm_flush_remote_tlbs_sptep(kvm, sptep); |
1214 | } |
1215 | |
1216 | /* |
1217 | * Write-protect on the specified @sptep, @pt_protect indicates whether |
1218 | * spte write-protection is caused by protecting shadow page table. |
1219 | * |
1220 | * Note: write protection is difference between dirty logging and spte |
1221 | * protection: |
1222 | * - for dirty logging, the spte can be set to writable at anytime if |
1223 | * its dirty bitmap is properly set. |
1224 | * - for spte protection, the spte can be writable only after unsync-ing |
1225 | * shadow page. |
1226 | * |
1227 | * Return true if tlb need be flushed. |
1228 | */ |
1229 | static bool spte_write_protect(u64 *sptep, bool pt_protect) |
1230 | { |
1231 | u64 spte = *sptep; |
1232 | |
1233 | if (!is_writable_pte(pte: spte) && |
1234 | !(pt_protect && is_mmu_writable_spte(spte))) |
1235 | return false; |
1236 | |
1237 | if (pt_protect) |
1238 | spte &= ~shadow_mmu_writable_mask; |
1239 | spte = spte & ~PT_WRITABLE_MASK; |
1240 | |
1241 | return mmu_spte_update(sptep, new_spte: spte); |
1242 | } |
1243 | |
1244 | static bool rmap_write_protect(struct kvm_rmap_head *rmap_head, |
1245 | bool pt_protect) |
1246 | { |
1247 | u64 *sptep; |
1248 | struct rmap_iterator iter; |
1249 | bool flush = false; |
1250 | |
1251 | for_each_rmap_spte(rmap_head, &iter, sptep) |
1252 | flush |= spte_write_protect(sptep, pt_protect); |
1253 | |
1254 | return flush; |
1255 | } |
1256 | |
1257 | static bool spte_clear_dirty(u64 *sptep) |
1258 | { |
1259 | u64 spte = *sptep; |
1260 | |
1261 | KVM_MMU_WARN_ON(!spte_ad_enabled(spte)); |
1262 | spte &= ~shadow_dirty_mask; |
1263 | return mmu_spte_update(sptep, new_spte: spte); |
1264 | } |
1265 | |
1266 | static bool spte_wrprot_for_clear_dirty(u64 *sptep) |
1267 | { |
1268 | bool was_writable = test_and_clear_bit(nr: PT_WRITABLE_SHIFT, |
1269 | addr: (unsigned long *)sptep); |
1270 | if (was_writable && !spte_ad_enabled(spte: *sptep)) |
1271 | kvm_set_pfn_dirty(pfn: spte_to_pfn(pte: *sptep)); |
1272 | |
1273 | return was_writable; |
1274 | } |
1275 | |
1276 | /* |
1277 | * Gets the GFN ready for another round of dirty logging by clearing the |
1278 | * - D bit on ad-enabled SPTEs, and |
1279 | * - W bit on ad-disabled SPTEs. |
1280 | * Returns true iff any D or W bits were cleared. |
1281 | */ |
1282 | static bool __rmap_clear_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head, |
1283 | const struct kvm_memory_slot *slot) |
1284 | { |
1285 | u64 *sptep; |
1286 | struct rmap_iterator iter; |
1287 | bool flush = false; |
1288 | |
1289 | for_each_rmap_spte(rmap_head, &iter, sptep) |
1290 | if (spte_ad_need_write_protect(spte: *sptep)) |
1291 | flush |= spte_wrprot_for_clear_dirty(sptep); |
1292 | else |
1293 | flush |= spte_clear_dirty(sptep); |
1294 | |
1295 | return flush; |
1296 | } |
1297 | |
1298 | /** |
1299 | * kvm_mmu_write_protect_pt_masked - write protect selected PT level pages |
1300 | * @kvm: kvm instance |
1301 | * @slot: slot to protect |
1302 | * @gfn_offset: start of the BITS_PER_LONG pages we care about |
1303 | * @mask: indicates which pages we should protect |
1304 | * |
1305 | * Used when we do not need to care about huge page mappings. |
1306 | */ |
1307 | static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, |
1308 | struct kvm_memory_slot *slot, |
1309 | gfn_t gfn_offset, unsigned long mask) |
1310 | { |
1311 | struct kvm_rmap_head *rmap_head; |
1312 | |
1313 | if (tdp_mmu_enabled) |
1314 | kvm_tdp_mmu_clear_dirty_pt_masked(kvm, slot, |
1315 | gfn: slot->base_gfn + gfn_offset, mask, wrprot: true); |
1316 | |
1317 | if (!kvm_memslots_have_rmaps(kvm)) |
1318 | return; |
1319 | |
1320 | while (mask) { |
1321 | rmap_head = gfn_to_rmap(gfn: slot->base_gfn + gfn_offset + __ffs(mask), |
1322 | level: PG_LEVEL_4K, slot); |
1323 | rmap_write_protect(rmap_head, pt_protect: false); |
1324 | |
1325 | /* clear the first set bit */ |
1326 | mask &= mask - 1; |
1327 | } |
1328 | } |
1329 | |
1330 | /** |
1331 | * kvm_mmu_clear_dirty_pt_masked - clear MMU D-bit for PT level pages, or write |
1332 | * protect the page if the D-bit isn't supported. |
1333 | * @kvm: kvm instance |
1334 | * @slot: slot to clear D-bit |
1335 | * @gfn_offset: start of the BITS_PER_LONG pages we care about |
1336 | * @mask: indicates which pages we should clear D-bit |
1337 | * |
1338 | * Used for PML to re-log the dirty GPAs after userspace querying dirty_bitmap. |
1339 | */ |
1340 | static void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm, |
1341 | struct kvm_memory_slot *slot, |
1342 | gfn_t gfn_offset, unsigned long mask) |
1343 | { |
1344 | struct kvm_rmap_head *rmap_head; |
1345 | |
1346 | if (tdp_mmu_enabled) |
1347 | kvm_tdp_mmu_clear_dirty_pt_masked(kvm, slot, |
1348 | gfn: slot->base_gfn + gfn_offset, mask, wrprot: false); |
1349 | |
1350 | if (!kvm_memslots_have_rmaps(kvm)) |
1351 | return; |
1352 | |
1353 | while (mask) { |
1354 | rmap_head = gfn_to_rmap(gfn: slot->base_gfn + gfn_offset + __ffs(mask), |
1355 | level: PG_LEVEL_4K, slot); |
1356 | __rmap_clear_dirty(kvm, rmap_head, slot); |
1357 | |
1358 | /* clear the first set bit */ |
1359 | mask &= mask - 1; |
1360 | } |
1361 | } |
1362 | |
1363 | /** |
1364 | * kvm_arch_mmu_enable_log_dirty_pt_masked - enable dirty logging for selected |
1365 | * PT level pages. |
1366 | * |
1367 | * It calls kvm_mmu_write_protect_pt_masked to write protect selected pages to |
1368 | * enable dirty logging for them. |
1369 | * |
1370 | * We need to care about huge page mappings: e.g. during dirty logging we may |
1371 | * have such mappings. |
1372 | */ |
1373 | void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm, |
1374 | struct kvm_memory_slot *slot, |
1375 | gfn_t gfn_offset, unsigned long mask) |
1376 | { |
1377 | /* |
1378 | * Huge pages are NOT write protected when we start dirty logging in |
1379 | * initially-all-set mode; must write protect them here so that they |
1380 | * are split to 4K on the first write. |
1381 | * |
1382 | * The gfn_offset is guaranteed to be aligned to 64, but the base_gfn |
1383 | * of memslot has no such restriction, so the range can cross two large |
1384 | * pages. |
1385 | */ |
1386 | if (kvm_dirty_log_manual_protect_and_init_set(kvm)) { |
1387 | gfn_t start = slot->base_gfn + gfn_offset + __ffs(mask); |
1388 | gfn_t end = slot->base_gfn + gfn_offset + __fls(word: mask); |
1389 | |
1390 | if (READ_ONCE(eager_page_split)) |
1391 | kvm_mmu_try_split_huge_pages(kvm, memslot: slot, start, end: end + 1, target_level: PG_LEVEL_4K); |
1392 | |
1393 | kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn: start, min_level: PG_LEVEL_2M); |
1394 | |
1395 | /* Cross two large pages? */ |
1396 | if (ALIGN(start << PAGE_SHIFT, PMD_SIZE) != |
1397 | ALIGN(end << PAGE_SHIFT, PMD_SIZE)) |
1398 | kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn: end, |
1399 | min_level: PG_LEVEL_2M); |
1400 | } |
1401 | |
1402 | /* Now handle 4K PTEs. */ |
1403 | if (kvm_x86_ops.cpu_dirty_log_size) |
1404 | kvm_mmu_clear_dirty_pt_masked(kvm, slot, gfn_offset, mask); |
1405 | else |
1406 | kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask); |
1407 | } |
1408 | |
1409 | int kvm_cpu_dirty_log_size(void) |
1410 | { |
1411 | return kvm_x86_ops.cpu_dirty_log_size; |
1412 | } |
1413 | |
1414 | bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm, |
1415 | struct kvm_memory_slot *slot, u64 gfn, |
1416 | int min_level) |
1417 | { |
1418 | struct kvm_rmap_head *rmap_head; |
1419 | int i; |
1420 | bool write_protected = false; |
1421 | |
1422 | if (kvm_memslots_have_rmaps(kvm)) { |
1423 | for (i = min_level; i <= KVM_MAX_HUGEPAGE_LEVEL; ++i) { |
1424 | rmap_head = gfn_to_rmap(gfn, level: i, slot); |
1425 | write_protected |= rmap_write_protect(rmap_head, pt_protect: true); |
1426 | } |
1427 | } |
1428 | |
1429 | if (tdp_mmu_enabled) |
1430 | write_protected |= |
1431 | kvm_tdp_mmu_write_protect_gfn(kvm, slot, gfn, min_level); |
1432 | |
1433 | return write_protected; |
1434 | } |
1435 | |
1436 | static bool kvm_vcpu_write_protect_gfn(struct kvm_vcpu *vcpu, u64 gfn) |
1437 | { |
1438 | struct kvm_memory_slot *slot; |
1439 | |
1440 | slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); |
1441 | return kvm_mmu_slot_gfn_write_protect(kvm: vcpu->kvm, slot, gfn, min_level: PG_LEVEL_4K); |
1442 | } |
1443 | |
1444 | static bool __kvm_zap_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, |
1445 | const struct kvm_memory_slot *slot) |
1446 | { |
1447 | return kvm_zap_all_rmap_sptes(kvm, rmap_head); |
1448 | } |
1449 | |
1450 | static bool kvm_zap_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, |
1451 | struct kvm_memory_slot *slot, gfn_t gfn, int level, |
1452 | pte_t unused) |
1453 | { |
1454 | return __kvm_zap_rmap(kvm, rmap_head, slot); |
1455 | } |
1456 | |
1457 | static bool kvm_set_pte_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, |
1458 | struct kvm_memory_slot *slot, gfn_t gfn, int level, |
1459 | pte_t pte) |
1460 | { |
1461 | u64 *sptep; |
1462 | struct rmap_iterator iter; |
1463 | bool need_flush = false; |
1464 | u64 new_spte; |
1465 | kvm_pfn_t new_pfn; |
1466 | |
1467 | WARN_ON_ONCE(pte_huge(pte)); |
1468 | new_pfn = pte_pfn(pte); |
1469 | |
1470 | restart: |
1471 | for_each_rmap_spte(rmap_head, &iter, sptep) { |
1472 | need_flush = true; |
1473 | |
1474 | if (pte_write(pte)) { |
1475 | kvm_zap_one_rmap_spte(kvm, rmap_head, sptep); |
1476 | goto restart; |
1477 | } else { |
1478 | new_spte = kvm_mmu_changed_pte_notifier_make_spte( |
1479 | old_spte: *sptep, new_pfn); |
1480 | |
1481 | mmu_spte_clear_track_bits(kvm, sptep); |
1482 | mmu_spte_set(sptep, new_spte); |
1483 | } |
1484 | } |
1485 | |
1486 | if (need_flush && kvm_available_flush_remote_tlbs_range()) { |
1487 | kvm_flush_remote_tlbs_gfn(kvm, gfn, level); |
1488 | return false; |
1489 | } |
1490 | |
1491 | return need_flush; |
1492 | } |
1493 | |
1494 | struct slot_rmap_walk_iterator { |
1495 | /* input fields. */ |
1496 | const struct kvm_memory_slot *slot; |
1497 | gfn_t start_gfn; |
1498 | gfn_t end_gfn; |
1499 | int start_level; |
1500 | int end_level; |
1501 | |
1502 | /* output fields. */ |
1503 | gfn_t gfn; |
1504 | struct kvm_rmap_head *rmap; |
1505 | int level; |
1506 | |
1507 | /* private field. */ |
1508 | struct kvm_rmap_head *end_rmap; |
1509 | }; |
1510 | |
1511 | static void rmap_walk_init_level(struct slot_rmap_walk_iterator *iterator, |
1512 | int level) |
1513 | { |
1514 | iterator->level = level; |
1515 | iterator->gfn = iterator->start_gfn; |
1516 | iterator->rmap = gfn_to_rmap(gfn: iterator->gfn, level, slot: iterator->slot); |
1517 | iterator->end_rmap = gfn_to_rmap(gfn: iterator->end_gfn, level, slot: iterator->slot); |
1518 | } |
1519 | |
1520 | static void slot_rmap_walk_init(struct slot_rmap_walk_iterator *iterator, |
1521 | const struct kvm_memory_slot *slot, |
1522 | int start_level, int end_level, |
1523 | gfn_t start_gfn, gfn_t end_gfn) |
1524 | { |
1525 | iterator->slot = slot; |
1526 | iterator->start_level = start_level; |
1527 | iterator->end_level = end_level; |
1528 | iterator->start_gfn = start_gfn; |
1529 | iterator->end_gfn = end_gfn; |
1530 | |
1531 | rmap_walk_init_level(iterator, level: iterator->start_level); |
1532 | } |
1533 | |
1534 | static bool slot_rmap_walk_okay(struct slot_rmap_walk_iterator *iterator) |
1535 | { |
1536 | return !!iterator->rmap; |
1537 | } |
1538 | |
1539 | static void slot_rmap_walk_next(struct slot_rmap_walk_iterator *iterator) |
1540 | { |
1541 | while (++iterator->rmap <= iterator->end_rmap) { |
1542 | iterator->gfn += (1UL << KVM_HPAGE_GFN_SHIFT(iterator->level)); |
1543 | |
1544 | if (iterator->rmap->val) |
1545 | return; |
1546 | } |
1547 | |
1548 | if (++iterator->level > iterator->end_level) { |
1549 | iterator->rmap = NULL; |
1550 | return; |
1551 | } |
1552 | |
1553 | rmap_walk_init_level(iterator, level: iterator->level); |
1554 | } |
1555 | |
1556 | #define for_each_slot_rmap_range(_slot_, _start_level_, _end_level_, \ |
1557 | _start_gfn, _end_gfn, _iter_) \ |
1558 | for (slot_rmap_walk_init(_iter_, _slot_, _start_level_, \ |
1559 | _end_level_, _start_gfn, _end_gfn); \ |
1560 | slot_rmap_walk_okay(_iter_); \ |
1561 | slot_rmap_walk_next(_iter_)) |
1562 | |
1563 | typedef bool (*rmap_handler_t)(struct kvm *kvm, struct kvm_rmap_head *rmap_head, |
1564 | struct kvm_memory_slot *slot, gfn_t gfn, |
1565 | int level, pte_t pte); |
1566 | |
1567 | static __always_inline bool kvm_handle_gfn_range(struct kvm *kvm, |
1568 | struct kvm_gfn_range *range, |
1569 | rmap_handler_t handler) |
1570 | { |
1571 | struct slot_rmap_walk_iterator iterator; |
1572 | bool ret = false; |
1573 | |
1574 | for_each_slot_rmap_range(range->slot, PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL, |
1575 | range->start, range->end - 1, &iterator) |
1576 | ret |= handler(kvm, iterator.rmap, range->slot, iterator.gfn, |
1577 | iterator.level, range->arg.pte); |
1578 | |
1579 | return ret; |
1580 | } |
1581 | |
1582 | bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) |
1583 | { |
1584 | bool flush = false; |
1585 | |
1586 | if (kvm_memslots_have_rmaps(kvm)) |
1587 | flush = kvm_handle_gfn_range(kvm, range, handler: kvm_zap_rmap); |
1588 | |
1589 | if (tdp_mmu_enabled) |
1590 | flush = kvm_tdp_mmu_unmap_gfn_range(kvm, range, flush); |
1591 | |
1592 | if (kvm_x86_ops.set_apic_access_page_addr && |
1593 | range->slot->id == APIC_ACCESS_PAGE_PRIVATE_MEMSLOT) |
1594 | kvm_make_all_cpus_request(kvm, KVM_REQ_APIC_PAGE_RELOAD); |
1595 | |
1596 | return flush; |
1597 | } |
1598 | |
1599 | bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range) |
1600 | { |
1601 | bool flush = false; |
1602 | |
1603 | if (kvm_memslots_have_rmaps(kvm)) |
1604 | flush = kvm_handle_gfn_range(kvm, range, handler: kvm_set_pte_rmap); |
1605 | |
1606 | if (tdp_mmu_enabled) |
1607 | flush |= kvm_tdp_mmu_set_spte_gfn(kvm, range); |
1608 | |
1609 | return flush; |
1610 | } |
1611 | |
1612 | static bool kvm_age_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, |
1613 | struct kvm_memory_slot *slot, gfn_t gfn, int level, |
1614 | pte_t unused) |
1615 | { |
1616 | u64 *sptep; |
1617 | struct rmap_iterator iter; |
1618 | int young = 0; |
1619 | |
1620 | for_each_rmap_spte(rmap_head, &iter, sptep) |
1621 | young |= mmu_spte_age(sptep); |
1622 | |
1623 | return young; |
1624 | } |
1625 | |
1626 | static bool kvm_test_age_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, |
1627 | struct kvm_memory_slot *slot, gfn_t gfn, |
1628 | int level, pte_t unused) |
1629 | { |
1630 | u64 *sptep; |
1631 | struct rmap_iterator iter; |
1632 | |
1633 | for_each_rmap_spte(rmap_head, &iter, sptep) |
1634 | if (is_accessed_spte(spte: *sptep)) |
1635 | return true; |
1636 | return false; |
1637 | } |
1638 | |
1639 | #define RMAP_RECYCLE_THRESHOLD 1000 |
1640 | |
1641 | static void __rmap_add(struct kvm *kvm, |
1642 | struct kvm_mmu_memory_cache *cache, |
1643 | const struct kvm_memory_slot *slot, |
1644 | u64 *spte, gfn_t gfn, unsigned int access) |
1645 | { |
1646 | struct kvm_mmu_page *sp; |
1647 | struct kvm_rmap_head *rmap_head; |
1648 | int rmap_count; |
1649 | |
1650 | sp = sptep_to_sp(sptep: spte); |
1651 | kvm_mmu_page_set_translation(sp, index: spte_index(sptep: spte), gfn, access); |
1652 | kvm_update_page_stats(kvm, sp->role.level, 1); |
1653 | |
1654 | rmap_head = gfn_to_rmap(gfn, level: sp->role.level, slot); |
1655 | rmap_count = pte_list_add(cache, spte, rmap_head); |
1656 | |
1657 | if (rmap_count > kvm->stat.max_mmu_rmap_size) |
1658 | kvm->stat.max_mmu_rmap_size = rmap_count; |
1659 | if (rmap_count > RMAP_RECYCLE_THRESHOLD) { |
1660 | kvm_zap_all_rmap_sptes(kvm, rmap_head); |
1661 | kvm_flush_remote_tlbs_gfn(kvm, gfn, level: sp->role.level); |
1662 | } |
1663 | } |
1664 | |
1665 | static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot, |
1666 | u64 *spte, gfn_t gfn, unsigned int access) |
1667 | { |
1668 | struct kvm_mmu_memory_cache *cache = &vcpu->arch.mmu_pte_list_desc_cache; |
1669 | |
1670 | __rmap_add(kvm: vcpu->kvm, cache, slot, spte, gfn, access); |
1671 | } |
1672 | |
1673 | bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) |
1674 | { |
1675 | bool young = false; |
1676 | |
1677 | if (kvm_memslots_have_rmaps(kvm)) |
1678 | young = kvm_handle_gfn_range(kvm, range, handler: kvm_age_rmap); |
1679 | |
1680 | if (tdp_mmu_enabled) |
1681 | young |= kvm_tdp_mmu_age_gfn_range(kvm, range); |
1682 | |
1683 | return young; |
1684 | } |
1685 | |
1686 | bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) |
1687 | { |
1688 | bool young = false; |
1689 | |
1690 | if (kvm_memslots_have_rmaps(kvm)) |
1691 | young = kvm_handle_gfn_range(kvm, range, handler: kvm_test_age_rmap); |
1692 | |
1693 | if (tdp_mmu_enabled) |
1694 | young |= kvm_tdp_mmu_test_age_gfn(kvm, range); |
1695 | |
1696 | return young; |
1697 | } |
1698 | |
1699 | static void kvm_mmu_check_sptes_at_free(struct kvm_mmu_page *sp) |
1700 | { |
1701 | #ifdef CONFIG_KVM_PROVE_MMU |
1702 | int i; |
1703 | |
1704 | for (i = 0; i < SPTE_ENT_PER_PAGE; i++) { |
1705 | if (KVM_MMU_WARN_ON(is_shadow_present_pte(sp->spt[i]))) |
1706 | pr_err_ratelimited("SPTE %llx (@ %p) for gfn %llx shadow-present at free" , |
1707 | sp->spt[i], &sp->spt[i], |
1708 | kvm_mmu_page_get_gfn(sp, i)); |
1709 | } |
1710 | #endif |
1711 | } |
1712 | |
1713 | /* |
1714 | * This value is the sum of all of the kvm instances's |
1715 | * kvm->arch.n_used_mmu_pages values. We need a global, |
1716 | * aggregate version in order to make the slab shrinker |
1717 | * faster |
1718 | */ |
1719 | static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, long nr) |
1720 | { |
1721 | kvm->arch.n_used_mmu_pages += nr; |
1722 | percpu_counter_add(fbc: &kvm_total_used_mmu_pages, amount: nr); |
1723 | } |
1724 | |
1725 | static void kvm_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) |
1726 | { |
1727 | kvm_mod_used_mmu_pages(kvm, nr: +1); |
1728 | kvm_account_pgtable_pages(virt: (void *)sp->spt, nr: +1); |
1729 | } |
1730 | |
1731 | static void kvm_unaccount_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) |
1732 | { |
1733 | kvm_mod_used_mmu_pages(kvm, nr: -1); |
1734 | kvm_account_pgtable_pages(virt: (void *)sp->spt, nr: -1); |
1735 | } |
1736 | |
1737 | static void kvm_mmu_free_shadow_page(struct kvm_mmu_page *sp) |
1738 | { |
1739 | kvm_mmu_check_sptes_at_free(sp); |
1740 | |
1741 | hlist_del(n: &sp->hash_link); |
1742 | list_del(entry: &sp->link); |
1743 | free_page((unsigned long)sp->spt); |
1744 | if (!sp->role.direct) |
1745 | free_page((unsigned long)sp->shadowed_translation); |
1746 | kmem_cache_free(s: mmu_page_header_cache, objp: sp); |
1747 | } |
1748 | |
1749 | static unsigned kvm_page_table_hashfn(gfn_t gfn) |
1750 | { |
1751 | return hash_64(val: gfn, KVM_MMU_HASH_SHIFT); |
1752 | } |
1753 | |
1754 | static void mmu_page_add_parent_pte(struct kvm_mmu_memory_cache *cache, |
1755 | struct kvm_mmu_page *sp, u64 *parent_pte) |
1756 | { |
1757 | if (!parent_pte) |
1758 | return; |
1759 | |
1760 | pte_list_add(cache, spte: parent_pte, rmap_head: &sp->parent_ptes); |
1761 | } |
1762 | |
1763 | static void mmu_page_remove_parent_pte(struct kvm *kvm, struct kvm_mmu_page *sp, |
1764 | u64 *parent_pte) |
1765 | { |
1766 | pte_list_remove(kvm, spte: parent_pte, rmap_head: &sp->parent_ptes); |
1767 | } |
1768 | |
1769 | static void drop_parent_pte(struct kvm *kvm, struct kvm_mmu_page *sp, |
1770 | u64 *parent_pte) |
1771 | { |
1772 | mmu_page_remove_parent_pte(kvm, sp, parent_pte); |
1773 | mmu_spte_clear_no_track(sptep: parent_pte); |
1774 | } |
1775 | |
1776 | static void mark_unsync(u64 *spte); |
1777 | static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp) |
1778 | { |
1779 | u64 *sptep; |
1780 | struct rmap_iterator iter; |
1781 | |
1782 | for_each_rmap_spte(&sp->parent_ptes, &iter, sptep) { |
1783 | mark_unsync(spte: sptep); |
1784 | } |
1785 | } |
1786 | |
1787 | static void mark_unsync(u64 *spte) |
1788 | { |
1789 | struct kvm_mmu_page *sp; |
1790 | |
1791 | sp = sptep_to_sp(sptep: spte); |
1792 | if (__test_and_set_bit(spte_index(spte), sp->unsync_child_bitmap)) |
1793 | return; |
1794 | if (sp->unsync_children++) |
1795 | return; |
1796 | kvm_mmu_mark_parents_unsync(sp); |
1797 | } |
1798 | |
1799 | #define KVM_PAGE_ARRAY_NR 16 |
1800 | |
1801 | struct kvm_mmu_pages { |
1802 | struct mmu_page_and_offset { |
1803 | struct kvm_mmu_page *sp; |
1804 | unsigned int idx; |
1805 | } page[KVM_PAGE_ARRAY_NR]; |
1806 | unsigned int nr; |
1807 | }; |
1808 | |
1809 | static int mmu_pages_add(struct kvm_mmu_pages *pvec, struct kvm_mmu_page *sp, |
1810 | int idx) |
1811 | { |
1812 | int i; |
1813 | |
1814 | if (sp->unsync) |
1815 | for (i=0; i < pvec->nr; i++) |
1816 | if (pvec->page[i].sp == sp) |
1817 | return 0; |
1818 | |
1819 | pvec->page[pvec->nr].sp = sp; |
1820 | pvec->page[pvec->nr].idx = idx; |
1821 | pvec->nr++; |
1822 | return (pvec->nr == KVM_PAGE_ARRAY_NR); |
1823 | } |
1824 | |
1825 | static inline void clear_unsync_child_bit(struct kvm_mmu_page *sp, int idx) |
1826 | { |
1827 | --sp->unsync_children; |
1828 | WARN_ON_ONCE((int)sp->unsync_children < 0); |
1829 | __clear_bit(idx, sp->unsync_child_bitmap); |
1830 | } |
1831 | |
1832 | static int __mmu_unsync_walk(struct kvm_mmu_page *sp, |
1833 | struct kvm_mmu_pages *pvec) |
1834 | { |
1835 | int i, ret, nr_unsync_leaf = 0; |
1836 | |
1837 | for_each_set_bit(i, sp->unsync_child_bitmap, 512) { |
1838 | struct kvm_mmu_page *child; |
1839 | u64 ent = sp->spt[i]; |
1840 | |
1841 | if (!is_shadow_present_pte(pte: ent) || is_large_pte(pte: ent)) { |
1842 | clear_unsync_child_bit(sp, idx: i); |
1843 | continue; |
1844 | } |
1845 | |
1846 | child = spte_to_child_sp(spte: ent); |
1847 | |
1848 | if (child->unsync_children) { |
1849 | if (mmu_pages_add(pvec, sp: child, idx: i)) |
1850 | return -ENOSPC; |
1851 | |
1852 | ret = __mmu_unsync_walk(sp: child, pvec); |
1853 | if (!ret) { |
1854 | clear_unsync_child_bit(sp, idx: i); |
1855 | continue; |
1856 | } else if (ret > 0) { |
1857 | nr_unsync_leaf += ret; |
1858 | } else |
1859 | return ret; |
1860 | } else if (child->unsync) { |
1861 | nr_unsync_leaf++; |
1862 | if (mmu_pages_add(pvec, sp: child, idx: i)) |
1863 | return -ENOSPC; |
1864 | } else |
1865 | clear_unsync_child_bit(sp, idx: i); |
1866 | } |
1867 | |
1868 | return nr_unsync_leaf; |
1869 | } |
1870 | |
1871 | #define INVALID_INDEX (-1) |
1872 | |
1873 | static int mmu_unsync_walk(struct kvm_mmu_page *sp, |
1874 | struct kvm_mmu_pages *pvec) |
1875 | { |
1876 | pvec->nr = 0; |
1877 | if (!sp->unsync_children) |
1878 | return 0; |
1879 | |
1880 | mmu_pages_add(pvec, sp, INVALID_INDEX); |
1881 | return __mmu_unsync_walk(sp, pvec); |
1882 | } |
1883 | |
1884 | static void kvm_unlink_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) |
1885 | { |
1886 | WARN_ON_ONCE(!sp->unsync); |
1887 | trace_kvm_mmu_sync_page(sp); |
1888 | sp->unsync = 0; |
1889 | --kvm->stat.mmu_unsync; |
1890 | } |
1891 | |
1892 | static bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, |
1893 | struct list_head *invalid_list); |
1894 | static void kvm_mmu_commit_zap_page(struct kvm *kvm, |
1895 | struct list_head *invalid_list); |
1896 | |
1897 | static bool sp_has_gptes(struct kvm_mmu_page *sp) |
1898 | { |
1899 | if (sp->role.direct) |
1900 | return false; |
1901 | |
1902 | if (sp->role.passthrough) |
1903 | return false; |
1904 | |
1905 | return true; |
1906 | } |
1907 | |
1908 | #define for_each_valid_sp(_kvm, _sp, _list) \ |
1909 | hlist_for_each_entry(_sp, _list, hash_link) \ |
1910 | if (is_obsolete_sp((_kvm), (_sp))) { \ |
1911 | } else |
1912 | |
1913 | #define for_each_gfn_valid_sp_with_gptes(_kvm, _sp, _gfn) \ |
1914 | for_each_valid_sp(_kvm, _sp, \ |
1915 | &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)]) \ |
1916 | if ((_sp)->gfn != (_gfn) || !sp_has_gptes(_sp)) {} else |
1917 | |
1918 | static bool kvm_sync_page_check(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) |
1919 | { |
1920 | union kvm_mmu_page_role root_role = vcpu->arch.mmu->root_role; |
1921 | |
1922 | /* |
1923 | * Ignore various flags when verifying that it's safe to sync a shadow |
1924 | * page using the current MMU context. |
1925 | * |
1926 | * - level: not part of the overall MMU role and will never match as the MMU's |
1927 | * level tracks the root level |
1928 | * - access: updated based on the new guest PTE |
1929 | * - quadrant: not part of the overall MMU role (similar to level) |
1930 | */ |
1931 | const union kvm_mmu_page_role sync_role_ign = { |
1932 | .level = 0xf, |
1933 | .access = 0x7, |
1934 | .quadrant = 0x3, |
1935 | .passthrough = 0x1, |
1936 | }; |
1937 | |
1938 | /* |
1939 | * Direct pages can never be unsync, and KVM should never attempt to |
1940 | * sync a shadow page for a different MMU context, e.g. if the role |
1941 | * differs then the memslot lookup (SMM vs. non-SMM) will be bogus, the |
1942 | * reserved bits checks will be wrong, etc... |
1943 | */ |
1944 | if (WARN_ON_ONCE(sp->role.direct || !vcpu->arch.mmu->sync_spte || |
1945 | (sp->role.word ^ root_role.word) & ~sync_role_ign.word)) |
1946 | return false; |
1947 | |
1948 | return true; |
1949 | } |
1950 | |
1951 | static int kvm_sync_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, int i) |
1952 | { |
1953 | if (!sp->spt[i]) |
1954 | return 0; |
1955 | |
1956 | return vcpu->arch.mmu->sync_spte(vcpu, sp, i); |
1957 | } |
1958 | |
1959 | static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) |
1960 | { |
1961 | int flush = 0; |
1962 | int i; |
1963 | |
1964 | if (!kvm_sync_page_check(vcpu, sp)) |
1965 | return -1; |
1966 | |
1967 | for (i = 0; i < SPTE_ENT_PER_PAGE; i++) { |
1968 | int ret = kvm_sync_spte(vcpu, sp, i); |
1969 | |
1970 | if (ret < -1) |
1971 | return -1; |
1972 | flush |= ret; |
1973 | } |
1974 | |
1975 | /* |
1976 | * Note, any flush is purely for KVM's correctness, e.g. when dropping |
1977 | * an existing SPTE or clearing W/A/D bits to ensure an mmu_notifier |
1978 | * unmap or dirty logging event doesn't fail to flush. The guest is |
1979 | * responsible for flushing the TLB to ensure any changes in protection |
1980 | * bits are recognized, i.e. until the guest flushes or page faults on |
1981 | * a relevant address, KVM is architecturally allowed to let vCPUs use |
1982 | * cached translations with the old protection bits. |
1983 | */ |
1984 | return flush; |
1985 | } |
1986 | |
1987 | static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, |
1988 | struct list_head *invalid_list) |
1989 | { |
1990 | int ret = __kvm_sync_page(vcpu, sp); |
1991 | |
1992 | if (ret < 0) |
1993 | kvm_mmu_prepare_zap_page(kvm: vcpu->kvm, sp, invalid_list); |
1994 | return ret; |
1995 | } |
1996 | |
1997 | static bool kvm_mmu_remote_flush_or_zap(struct kvm *kvm, |
1998 | struct list_head *invalid_list, |
1999 | bool remote_flush) |
2000 | { |
2001 | if (!remote_flush && list_empty(head: invalid_list)) |
2002 | return false; |
2003 | |
2004 | if (!list_empty(head: invalid_list)) |
2005 | kvm_mmu_commit_zap_page(kvm, invalid_list); |
2006 | else |
2007 | kvm_flush_remote_tlbs(kvm); |
2008 | return true; |
2009 | } |
2010 | |
2011 | static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp) |
2012 | { |
2013 | if (sp->role.invalid) |
2014 | return true; |
2015 | |
2016 | /* TDP MMU pages do not use the MMU generation. */ |
2017 | return !is_tdp_mmu_page(sp) && |
2018 | unlikely(sp->mmu_valid_gen != kvm->arch.mmu_valid_gen); |
2019 | } |
2020 | |
2021 | struct mmu_page_path { |
2022 | struct kvm_mmu_page *parent[PT64_ROOT_MAX_LEVEL]; |
2023 | unsigned int idx[PT64_ROOT_MAX_LEVEL]; |
2024 | }; |
2025 | |
2026 | #define for_each_sp(pvec, sp, parents, i) \ |
2027 | for (i = mmu_pages_first(&pvec, &parents); \ |
2028 | i < pvec.nr && ({ sp = pvec.page[i].sp; 1;}); \ |
2029 | i = mmu_pages_next(&pvec, &parents, i)) |
2030 | |
2031 | static int mmu_pages_next(struct kvm_mmu_pages *pvec, |
2032 | struct mmu_page_path *parents, |
2033 | int i) |
2034 | { |
2035 | int n; |
2036 | |
2037 | for (n = i+1; n < pvec->nr; n++) { |
2038 | struct kvm_mmu_page *sp = pvec->page[n].sp; |
2039 | unsigned idx = pvec->page[n].idx; |
2040 | int level = sp->role.level; |
2041 | |
2042 | parents->idx[level-1] = idx; |
2043 | if (level == PG_LEVEL_4K) |
2044 | break; |
2045 | |
2046 | parents->parent[level-2] = sp; |
2047 | } |
2048 | |
2049 | return n; |
2050 | } |
2051 | |
2052 | static int mmu_pages_first(struct kvm_mmu_pages *pvec, |
2053 | struct mmu_page_path *parents) |
2054 | { |
2055 | struct kvm_mmu_page *sp; |
2056 | int level; |
2057 | |
2058 | if (pvec->nr == 0) |
2059 | return 0; |
2060 | |
2061 | WARN_ON_ONCE(pvec->page[0].idx != INVALID_INDEX); |
2062 | |
2063 | sp = pvec->page[0].sp; |
2064 | level = sp->role.level; |
2065 | WARN_ON_ONCE(level == PG_LEVEL_4K); |
2066 | |
2067 | parents->parent[level-2] = sp; |
2068 | |
2069 | /* Also set up a sentinel. Further entries in pvec are all |
2070 | * children of sp, so this element is never overwritten. |
2071 | */ |
2072 | parents->parent[level-1] = NULL; |
2073 | return mmu_pages_next(pvec, parents, i: 0); |
2074 | } |
2075 | |
2076 | static void mmu_pages_clear_parents(struct mmu_page_path *parents) |
2077 | { |
2078 | struct kvm_mmu_page *sp; |
2079 | unsigned int level = 0; |
2080 | |
2081 | do { |
2082 | unsigned int idx = parents->idx[level]; |
2083 | sp = parents->parent[level]; |
2084 | if (!sp) |
2085 | return; |
2086 | |
2087 | WARN_ON_ONCE(idx == INVALID_INDEX); |
2088 | clear_unsync_child_bit(sp, idx); |
2089 | level++; |
2090 | } while (!sp->unsync_children); |
2091 | } |
2092 | |
2093 | static int mmu_sync_children(struct kvm_vcpu *vcpu, |
2094 | struct kvm_mmu_page *parent, bool can_yield) |
2095 | { |
2096 | int i; |
2097 | struct kvm_mmu_page *sp; |
2098 | struct mmu_page_path parents; |
2099 | struct kvm_mmu_pages pages; |
2100 | LIST_HEAD(invalid_list); |
2101 | bool flush = false; |
2102 | |
2103 | while (mmu_unsync_walk(sp: parent, pvec: &pages)) { |
2104 | bool protected = false; |
2105 | |
2106 | for_each_sp(pages, sp, parents, i) |
2107 | protected |= kvm_vcpu_write_protect_gfn(vcpu, gfn: sp->gfn); |
2108 | |
2109 | if (protected) { |
2110 | kvm_mmu_remote_flush_or_zap(kvm: vcpu->kvm, invalid_list: &invalid_list, remote_flush: true); |
2111 | flush = false; |
2112 | } |
2113 | |
2114 | for_each_sp(pages, sp, parents, i) { |
2115 | kvm_unlink_unsync_page(kvm: vcpu->kvm, sp); |
2116 | flush |= kvm_sync_page(vcpu, sp, invalid_list: &invalid_list) > 0; |
2117 | mmu_pages_clear_parents(parents: &parents); |
2118 | } |
2119 | if (need_resched() || rwlock_needbreak(lock: &vcpu->kvm->mmu_lock)) { |
2120 | kvm_mmu_remote_flush_or_zap(kvm: vcpu->kvm, invalid_list: &invalid_list, remote_flush: flush); |
2121 | if (!can_yield) { |
2122 | kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); |
2123 | return -EINTR; |
2124 | } |
2125 | |
2126 | cond_resched_rwlock_write(&vcpu->kvm->mmu_lock); |
2127 | flush = false; |
2128 | } |
2129 | } |
2130 | |
2131 | kvm_mmu_remote_flush_or_zap(kvm: vcpu->kvm, invalid_list: &invalid_list, remote_flush: flush); |
2132 | return 0; |
2133 | } |
2134 | |
2135 | static void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp) |
2136 | { |
2137 | atomic_set(v: &sp->write_flooding_count, i: 0); |
2138 | } |
2139 | |
2140 | static void clear_sp_write_flooding_count(u64 *spte) |
2141 | { |
2142 | __clear_sp_write_flooding_count(sp: sptep_to_sp(sptep: spte)); |
2143 | } |
2144 | |
2145 | /* |
2146 | * The vCPU is required when finding indirect shadow pages; the shadow |
2147 | * page may already exist and syncing it needs the vCPU pointer in |
2148 | * order to read guest page tables. Direct shadow pages are never |
2149 | * unsync, thus @vcpu can be NULL if @role.direct is true. |
2150 | */ |
2151 | static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm *kvm, |
2152 | struct kvm_vcpu *vcpu, |
2153 | gfn_t gfn, |
2154 | struct hlist_head *sp_list, |
2155 | union kvm_mmu_page_role role) |
2156 | { |
2157 | struct kvm_mmu_page *sp; |
2158 | int ret; |
2159 | int collisions = 0; |
2160 | LIST_HEAD(invalid_list); |
2161 | |
2162 | for_each_valid_sp(kvm, sp, sp_list) { |
2163 | if (sp->gfn != gfn) { |
2164 | collisions++; |
2165 | continue; |
2166 | } |
2167 | |
2168 | if (sp->role.word != role.word) { |
2169 | /* |
2170 | * If the guest is creating an upper-level page, zap |
2171 | * unsync pages for the same gfn. While it's possible |
2172 | * the guest is using recursive page tables, in all |
2173 | * likelihood the guest has stopped using the unsync |
2174 | * page and is installing a completely unrelated page. |
2175 | * Unsync pages must not be left as is, because the new |
2176 | * upper-level page will be write-protected. |
2177 | */ |
2178 | if (role.level > PG_LEVEL_4K && sp->unsync) |
2179 | kvm_mmu_prepare_zap_page(kvm, sp, |
2180 | invalid_list: &invalid_list); |
2181 | continue; |
2182 | } |
2183 | |
2184 | /* unsync and write-flooding only apply to indirect SPs. */ |
2185 | if (sp->role.direct) |
2186 | goto out; |
2187 | |
2188 | if (sp->unsync) { |
2189 | if (KVM_BUG_ON(!vcpu, kvm)) |
2190 | break; |
2191 | |
2192 | /* |
2193 | * The page is good, but is stale. kvm_sync_page does |
2194 | * get the latest guest state, but (unlike mmu_unsync_children) |
2195 | * it doesn't write-protect the page or mark it synchronized! |
2196 | * This way the validity of the mapping is ensured, but the |
2197 | * overhead of write protection is not incurred until the |
2198 | * guest invalidates the TLB mapping. This allows multiple |
2199 | * SPs for a single gfn to be unsync. |
2200 | * |
2201 | * If the sync fails, the page is zapped. If so, break |
2202 | * in order to rebuild it. |
2203 | */ |
2204 | ret = kvm_sync_page(vcpu, sp, invalid_list: &invalid_list); |
2205 | if (ret < 0) |
2206 | break; |
2207 | |
2208 | WARN_ON_ONCE(!list_empty(&invalid_list)); |
2209 | if (ret > 0) |
2210 | kvm_flush_remote_tlbs(kvm); |
2211 | } |
2212 | |
2213 | __clear_sp_write_flooding_count(sp); |
2214 | |
2215 | goto out; |
2216 | } |
2217 | |
2218 | sp = NULL; |
2219 | ++kvm->stat.mmu_cache_miss; |
2220 | |
2221 | out: |
2222 | kvm_mmu_commit_zap_page(kvm, invalid_list: &invalid_list); |
2223 | |
2224 | if (collisions > kvm->stat.max_mmu_page_hash_collisions) |
2225 | kvm->stat.max_mmu_page_hash_collisions = collisions; |
2226 | return sp; |
2227 | } |
2228 | |
2229 | /* Caches used when allocating a new shadow page. */ |
2230 | struct shadow_page_caches { |
2231 | struct kvm_mmu_memory_cache *page_header_cache; |
2232 | struct kvm_mmu_memory_cache *shadow_page_cache; |
2233 | struct kvm_mmu_memory_cache *shadowed_info_cache; |
2234 | }; |
2235 | |
2236 | static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm, |
2237 | struct shadow_page_caches *caches, |
2238 | gfn_t gfn, |
2239 | struct hlist_head *sp_list, |
2240 | union kvm_mmu_page_role role) |
2241 | { |
2242 | struct kvm_mmu_page *sp; |
2243 | |
2244 | sp = kvm_mmu_memory_cache_alloc(mc: caches->page_header_cache); |
2245 | sp->spt = kvm_mmu_memory_cache_alloc(mc: caches->shadow_page_cache); |
2246 | if (!role.direct) |
2247 | sp->shadowed_translation = kvm_mmu_memory_cache_alloc(mc: caches->shadowed_info_cache); |
2248 | |
2249 | set_page_private(virt_to_page(sp->spt), private: (unsigned long)sp); |
2250 | |
2251 | INIT_LIST_HEAD(list: &sp->possible_nx_huge_page_link); |
2252 | |
2253 | /* |
2254 | * active_mmu_pages must be a FIFO list, as kvm_zap_obsolete_pages() |
2255 | * depends on valid pages being added to the head of the list. See |
2256 | * comments in kvm_zap_obsolete_pages(). |
2257 | */ |
2258 | sp->mmu_valid_gen = kvm->arch.mmu_valid_gen; |
2259 | list_add(new: &sp->link, head: &kvm->arch.active_mmu_pages); |
2260 | kvm_account_mmu_page(kvm, sp); |
2261 | |
2262 | sp->gfn = gfn; |
2263 | sp->role = role; |
2264 | hlist_add_head(n: &sp->hash_link, h: sp_list); |
2265 | if (sp_has_gptes(sp)) |
2266 | account_shadowed(kvm, sp); |
2267 | |
2268 | return sp; |
2269 | } |
2270 | |
2271 | /* Note, @vcpu may be NULL if @role.direct is true; see kvm_mmu_find_shadow_page. */ |
2272 | static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm *kvm, |
2273 | struct kvm_vcpu *vcpu, |
2274 | struct shadow_page_caches *caches, |
2275 | gfn_t gfn, |
2276 | union kvm_mmu_page_role role) |
2277 | { |
2278 | struct hlist_head *sp_list; |
2279 | struct kvm_mmu_page *sp; |
2280 | bool created = false; |
2281 | |
2282 | sp_list = &kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)]; |
2283 | |
2284 | sp = kvm_mmu_find_shadow_page(kvm, vcpu, gfn, sp_list, role); |
2285 | if (!sp) { |
2286 | created = true; |
2287 | sp = kvm_mmu_alloc_shadow_page(kvm, caches, gfn, sp_list, role); |
2288 | } |
2289 | |
2290 | trace_kvm_mmu_get_page(sp, created); |
2291 | return sp; |
2292 | } |
2293 | |
2294 | static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu, |
2295 | gfn_t gfn, |
2296 | union kvm_mmu_page_role role) |
2297 | { |
2298 | struct shadow_page_caches caches = { |
2299 | .page_header_cache = &vcpu->arch.mmu_page_header_cache, |
2300 | .shadow_page_cache = &vcpu->arch.mmu_shadow_page_cache, |
2301 | .shadowed_info_cache = &vcpu->arch.mmu_shadowed_info_cache, |
2302 | }; |
2303 | |
2304 | return __kvm_mmu_get_shadow_page(kvm: vcpu->kvm, vcpu, caches: &caches, gfn, role); |
2305 | } |
2306 | |
2307 | static union kvm_mmu_page_role kvm_mmu_child_role(u64 *sptep, bool direct, |
2308 | unsigned int access) |
2309 | { |
2310 | struct kvm_mmu_page *parent_sp = sptep_to_sp(sptep); |
2311 | union kvm_mmu_page_role role; |
2312 | |
2313 | role = parent_sp->role; |
2314 | role.level--; |
2315 | role.access = access; |
2316 | role.direct = direct; |
2317 | role.passthrough = 0; |
2318 | |
2319 | /* |
2320 | * If the guest has 4-byte PTEs then that means it's using 32-bit, |
2321 | * 2-level, non-PAE paging. KVM shadows such guests with PAE paging |
2322 | * (i.e. 8-byte PTEs). The difference in PTE size means that KVM must |
2323 | * shadow each guest page table with multiple shadow page tables, which |
2324 | * requires extra bookkeeping in the role. |
2325 | * |
2326 | * Specifically, to shadow the guest's page directory (which covers a |
2327 | * 4GiB address space), KVM uses 4 PAE page directories, each mapping |
2328 | * 1GiB of the address space. @role.quadrant encodes which quarter of |
2329 | * the address space each maps. |
2330 | * |
2331 | * To shadow the guest's page tables (which each map a 4MiB region), KVM |
2332 | * uses 2 PAE page tables, each mapping a 2MiB region. For these, |
2333 | * @role.quadrant encodes which half of the region they map. |
2334 | * |
2335 | * Concretely, a 4-byte PDE consumes bits 31:22, while an 8-byte PDE |
2336 | * consumes bits 29:21. To consume bits 31:30, KVM's uses 4 shadow |
2337 | * PDPTEs; those 4 PAE page directories are pre-allocated and their |
2338 | * quadrant is assigned in mmu_alloc_root(). A 4-byte PTE consumes |
2339 | * bits 21:12, while an 8-byte PTE consumes bits 20:12. To consume |
2340 | * bit 21 in the PTE (the child here), KVM propagates that bit to the |
2341 | * quadrant, i.e. sets quadrant to '0' or '1'. The parent 8-byte PDE |
2342 | * covers bit 21 (see above), thus the quadrant is calculated from the |
2343 | * _least_ significant bit of the PDE index. |
2344 | */ |
2345 | if (role.has_4_byte_gpte) { |
2346 | WARN_ON_ONCE(role.level != PG_LEVEL_4K); |
2347 | role.quadrant = spte_index(sptep) & 1; |
2348 | } |
2349 | |
2350 | return role; |
2351 | } |
2352 | |
2353 | static struct kvm_mmu_page *kvm_mmu_get_child_sp(struct kvm_vcpu *vcpu, |
2354 | u64 *sptep, gfn_t gfn, |
2355 | bool direct, unsigned int access) |
2356 | { |
2357 | union kvm_mmu_page_role role; |
2358 | |
2359 | if (is_shadow_present_pte(pte: *sptep) && !is_large_pte(pte: *sptep)) |
2360 | return ERR_PTR(error: -EEXIST); |
2361 | |
2362 | role = kvm_mmu_child_role(sptep, direct, access); |
2363 | return kvm_mmu_get_shadow_page(vcpu, gfn, role); |
2364 | } |
2365 | |
2366 | static void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterator, |
2367 | struct kvm_vcpu *vcpu, hpa_t root, |
2368 | u64 addr) |
2369 | { |
2370 | iterator->addr = addr; |
2371 | iterator->shadow_addr = root; |
2372 | iterator->level = vcpu->arch.mmu->root_role.level; |
2373 | |
2374 | if (iterator->level >= PT64_ROOT_4LEVEL && |
2375 | vcpu->arch.mmu->cpu_role.base.level < PT64_ROOT_4LEVEL && |
2376 | !vcpu->arch.mmu->root_role.direct) |
2377 | iterator->level = PT32E_ROOT_LEVEL; |
2378 | |
2379 | if (iterator->level == PT32E_ROOT_LEVEL) { |
2380 | /* |
2381 | * prev_root is currently only used for 64-bit hosts. So only |
2382 | * the active root_hpa is valid here. |
2383 | */ |
2384 | BUG_ON(root != vcpu->arch.mmu->root.hpa); |
2385 | |
2386 | iterator->shadow_addr |
2387 | = vcpu->arch.mmu->pae_root[(addr >> 30) & 3]; |
2388 | iterator->shadow_addr &= SPTE_BASE_ADDR_MASK; |
2389 | --iterator->level; |
2390 | if (!iterator->shadow_addr) |
2391 | iterator->level = 0; |
2392 | } |
2393 | } |
2394 | |
2395 | static void shadow_walk_init(struct kvm_shadow_walk_iterator *iterator, |
2396 | struct kvm_vcpu *vcpu, u64 addr) |
2397 | { |
2398 | shadow_walk_init_using_root(iterator, vcpu, root: vcpu->arch.mmu->root.hpa, |
2399 | addr); |
2400 | } |
2401 | |
2402 | static bool shadow_walk_okay(struct kvm_shadow_walk_iterator *iterator) |
2403 | { |
2404 | if (iterator->level < PG_LEVEL_4K) |
2405 | return false; |
2406 | |
2407 | iterator->index = SPTE_INDEX(iterator->addr, iterator->level); |
2408 | iterator->sptep = ((u64 *)__va(iterator->shadow_addr)) + iterator->index; |
2409 | return true; |
2410 | } |
2411 | |
2412 | static void __shadow_walk_next(struct kvm_shadow_walk_iterator *iterator, |
2413 | u64 spte) |
2414 | { |
2415 | if (!is_shadow_present_pte(pte: spte) || is_last_spte(pte: spte, level: iterator->level)) { |
2416 | iterator->level = 0; |
2417 | return; |
2418 | } |
2419 | |
2420 | iterator->shadow_addr = spte & SPTE_BASE_ADDR_MASK; |
2421 | --iterator->level; |
2422 | } |
2423 | |
2424 | static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator) |
2425 | { |
2426 | __shadow_walk_next(iterator, spte: *iterator->sptep); |
2427 | } |
2428 | |
2429 | static void __link_shadow_page(struct kvm *kvm, |
2430 | struct kvm_mmu_memory_cache *cache, u64 *sptep, |
2431 | struct kvm_mmu_page *sp, bool flush) |
2432 | { |
2433 | u64 spte; |
2434 | |
2435 | BUILD_BUG_ON(VMX_EPT_WRITABLE_MASK != PT_WRITABLE_MASK); |
2436 | |
2437 | /* |
2438 | * If an SPTE is present already, it must be a leaf and therefore |
2439 | * a large one. Drop it, and flush the TLB if needed, before |
2440 | * installing sp. |
2441 | */ |
2442 | if (is_shadow_present_pte(pte: *sptep)) |
2443 | drop_large_spte(kvm, sptep, flush); |
2444 | |
2445 | spte = make_nonleaf_spte(child_pt: sp->spt, ad_disabled: sp_ad_disabled(sp)); |
2446 | |
2447 | mmu_spte_set(sptep, new_spte: spte); |
2448 | |
2449 | mmu_page_add_parent_pte(cache, sp, parent_pte: sptep); |
2450 | |
2451 | /* |
2452 | * The non-direct sub-pagetable must be updated before linking. For |
2453 | * L1 sp, the pagetable is updated via kvm_sync_page() in |
2454 | * kvm_mmu_find_shadow_page() without write-protecting the gfn, |
2455 | * so sp->unsync can be true or false. For higher level non-direct |
2456 | * sp, the pagetable is updated/synced via mmu_sync_children() in |
2457 | * FNAME(fetch)(), so sp->unsync_children can only be false. |
2458 | * WARN_ON_ONCE() if anything happens unexpectedly. |
2459 | */ |
2460 | if (WARN_ON_ONCE(sp->unsync_children) || sp->unsync) |
2461 | mark_unsync(spte: sptep); |
2462 | } |
2463 | |
2464 | static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep, |
2465 | struct kvm_mmu_page *sp) |
2466 | { |
2467 | __link_shadow_page(kvm: vcpu->kvm, cache: &vcpu->arch.mmu_pte_list_desc_cache, sptep, sp, flush: true); |
2468 | } |
2469 | |
2470 | static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep, |
2471 | unsigned direct_access) |
2472 | { |
2473 | if (is_shadow_present_pte(pte: *sptep) && !is_large_pte(pte: *sptep)) { |
2474 | struct kvm_mmu_page *child; |
2475 | |
2476 | /* |
2477 | * For the direct sp, if the guest pte's dirty bit |
2478 | * changed form clean to dirty, it will corrupt the |
2479 | * sp's access: allow writable in the read-only sp, |
2480 | * so we should update the spte at this point to get |
2481 | * a new sp with the correct access. |
2482 | */ |
2483 | child = spte_to_child_sp(spte: *sptep); |
2484 | if (child->role.access == direct_access) |
2485 | return; |
2486 | |
2487 | drop_parent_pte(kvm: vcpu->kvm, sp: child, parent_pte: sptep); |
2488 | kvm_flush_remote_tlbs_sptep(kvm: vcpu->kvm, sptep); |
2489 | } |
2490 | } |
2491 | |
2492 | /* Returns the number of zapped non-leaf child shadow pages. */ |
2493 | static int mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp, |
2494 | u64 *spte, struct list_head *invalid_list) |
2495 | { |
2496 | u64 pte; |
2497 | struct kvm_mmu_page *child; |
2498 | |
2499 | pte = *spte; |
2500 | if (is_shadow_present_pte(pte)) { |
2501 | if (is_last_spte(pte, level: sp->role.level)) { |
2502 | drop_spte(kvm, sptep: spte); |
2503 | } else { |
2504 | child = spte_to_child_sp(spte: pte); |
2505 | drop_parent_pte(kvm, sp: child, parent_pte: spte); |
2506 | |
2507 | /* |
2508 | * Recursively zap nested TDP SPs, parentless SPs are |
2509 | * unlikely to be used again in the near future. This |
2510 | * avoids retaining a large number of stale nested SPs. |
2511 | */ |
2512 | if (tdp_enabled && invalid_list && |
2513 | child->role.guest_mode && !child->parent_ptes.val) |
2514 | return kvm_mmu_prepare_zap_page(kvm, sp: child, |
2515 | invalid_list); |
2516 | } |
2517 | } else if (is_mmio_spte(spte: pte)) { |
2518 | mmu_spte_clear_no_track(sptep: spte); |
2519 | } |
2520 | return 0; |
2521 | } |
2522 | |
2523 | static int kvm_mmu_page_unlink_children(struct kvm *kvm, |
2524 | struct kvm_mmu_page *sp, |
2525 | struct list_head *invalid_list) |
2526 | { |
2527 | int zapped = 0; |
2528 | unsigned i; |
2529 | |
2530 | for (i = 0; i < SPTE_ENT_PER_PAGE; ++i) |
2531 | zapped += mmu_page_zap_pte(kvm, sp, spte: sp->spt + i, invalid_list); |
2532 | |
2533 | return zapped; |
2534 | } |
2535 | |
2536 | static void kvm_mmu_unlink_parents(struct kvm *kvm, struct kvm_mmu_page *sp) |
2537 | { |
2538 | u64 *sptep; |
2539 | struct rmap_iterator iter; |
2540 | |
2541 | while ((sptep = rmap_get_first(rmap_head: &sp->parent_ptes, iter: &iter))) |
2542 | drop_parent_pte(kvm, sp, parent_pte: sptep); |
2543 | } |
2544 | |
2545 | static int mmu_zap_unsync_children(struct kvm *kvm, |
2546 | struct kvm_mmu_page *parent, |
2547 | struct list_head *invalid_list) |
2548 | { |
2549 | int i, zapped = 0; |
2550 | struct mmu_page_path parents; |
2551 | struct kvm_mmu_pages pages; |
2552 | |
2553 | if (parent->role.level == PG_LEVEL_4K) |
2554 | return 0; |
2555 | |
2556 | while (mmu_unsync_walk(sp: parent, pvec: &pages)) { |
2557 | struct kvm_mmu_page *sp; |
2558 | |
2559 | for_each_sp(pages, sp, parents, i) { |
2560 | kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); |
2561 | mmu_pages_clear_parents(parents: &parents); |
2562 | zapped++; |
2563 | } |
2564 | } |
2565 | |
2566 | return zapped; |
2567 | } |
2568 | |
2569 | static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, |
2570 | struct kvm_mmu_page *sp, |
2571 | struct list_head *invalid_list, |
2572 | int *nr_zapped) |
2573 | { |
2574 | bool list_unstable, zapped_root = false; |
2575 | |
2576 | lockdep_assert_held_write(&kvm->mmu_lock); |
2577 | trace_kvm_mmu_prepare_zap_page(sp); |
2578 | ++kvm->stat.mmu_shadow_zapped; |
2579 | *nr_zapped = mmu_zap_unsync_children(kvm, parent: sp, invalid_list); |
2580 | *nr_zapped += kvm_mmu_page_unlink_children(kvm, sp, invalid_list); |
2581 | kvm_mmu_unlink_parents(kvm, sp); |
2582 | |
2583 | /* Zapping children means active_mmu_pages has become unstable. */ |
2584 | list_unstable = *nr_zapped; |
2585 | |
2586 | if (!sp->role.invalid && sp_has_gptes(sp)) |
2587 | unaccount_shadowed(kvm, sp); |
2588 | |
2589 | if (sp->unsync) |
2590 | kvm_unlink_unsync_page(kvm, sp); |
2591 | if (!sp->root_count) { |
2592 | /* Count self */ |
2593 | (*nr_zapped)++; |
2594 | |
2595 | /* |
2596 | * Already invalid pages (previously active roots) are not on |
2597 | * the active page list. See list_del() in the "else" case of |
2598 | * !sp->root_count. |
2599 | */ |
2600 | if (sp->role.invalid) |
2601 | list_add(new: &sp->link, head: invalid_list); |
2602 | else |
2603 | list_move(list: &sp->link, head: invalid_list); |
2604 | kvm_unaccount_mmu_page(kvm, sp); |
2605 | } else { |
2606 | /* |
2607 | * Remove the active root from the active page list, the root |
2608 | * will be explicitly freed when the root_count hits zero. |
2609 | */ |
2610 | list_del(entry: &sp->link); |
2611 | |
2612 | /* |
2613 | * Obsolete pages cannot be used on any vCPUs, see the comment |
2614 | * in kvm_mmu_zap_all_fast(). Note, is_obsolete_sp() also |
2615 | * treats invalid shadow pages as being obsolete. |
2616 | */ |
2617 | zapped_root = !is_obsolete_sp(kvm, sp); |
2618 | } |
2619 | |
2620 | if (sp->nx_huge_page_disallowed) |
2621 | unaccount_nx_huge_page(kvm, sp); |
2622 | |
2623 | sp->role.invalid = 1; |
2624 | |
2625 | /* |
2626 | * Make the request to free obsolete roots after marking the root |
2627 | * invalid, otherwise other vCPUs may not see it as invalid. |
2628 | */ |
2629 | if (zapped_root) |
2630 | kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_FREE_OBSOLETE_ROOTS); |
2631 | return list_unstable; |
2632 | } |
2633 | |
2634 | static bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, |
2635 | struct list_head *invalid_list) |
2636 | { |
2637 | int nr_zapped; |
2638 | |
2639 | __kvm_mmu_prepare_zap_page(kvm, sp, invalid_list, nr_zapped: &nr_zapped); |
2640 | return nr_zapped; |
2641 | } |
2642 | |
2643 | static void kvm_mmu_commit_zap_page(struct kvm *kvm, |
2644 | struct list_head *invalid_list) |
2645 | { |
2646 | struct kvm_mmu_page *sp, *nsp; |
2647 | |
2648 | if (list_empty(head: invalid_list)) |
2649 | return; |
2650 | |
2651 | /* |
2652 | * We need to make sure everyone sees our modifications to |
2653 | * the page tables and see changes to vcpu->mode here. The barrier |
2654 | * in the kvm_flush_remote_tlbs() achieves this. This pairs |
2655 | * with vcpu_enter_guest and walk_shadow_page_lockless_begin/end. |
2656 | * |
2657 | * In addition, kvm_flush_remote_tlbs waits for all vcpus to exit |
2658 | * guest mode and/or lockless shadow page table walks. |
2659 | */ |
2660 | kvm_flush_remote_tlbs(kvm); |
2661 | |
2662 | list_for_each_entry_safe(sp, nsp, invalid_list, link) { |
2663 | WARN_ON_ONCE(!sp->role.invalid || sp->root_count); |
2664 | kvm_mmu_free_shadow_page(sp); |
2665 | } |
2666 | } |
2667 | |
2668 | static unsigned long kvm_mmu_zap_oldest_mmu_pages(struct kvm *kvm, |
2669 | unsigned long nr_to_zap) |
2670 | { |
2671 | unsigned long total_zapped = 0; |
2672 | struct kvm_mmu_page *sp, *tmp; |
2673 | LIST_HEAD(invalid_list); |
2674 | bool unstable; |
2675 | int nr_zapped; |
2676 | |
2677 | if (list_empty(head: &kvm->arch.active_mmu_pages)) |
2678 | return 0; |
2679 | |
2680 | restart: |
2681 | list_for_each_entry_safe_reverse(sp, tmp, &kvm->arch.active_mmu_pages, link) { |
2682 | /* |
2683 | * Don't zap active root pages, the page itself can't be freed |
2684 | * and zapping it will just force vCPUs to realloc and reload. |
2685 | */ |
2686 | if (sp->root_count) |
2687 | continue; |
2688 | |
2689 | unstable = __kvm_mmu_prepare_zap_page(kvm, sp, invalid_list: &invalid_list, |
2690 | nr_zapped: &nr_zapped); |
2691 | total_zapped += nr_zapped; |
2692 | if (total_zapped >= nr_to_zap) |
2693 | break; |
2694 | |
2695 | if (unstable) |
2696 | goto restart; |
2697 | } |
2698 | |
2699 | kvm_mmu_commit_zap_page(kvm, invalid_list: &invalid_list); |
2700 | |
2701 | kvm->stat.mmu_recycled += total_zapped; |
2702 | return total_zapped; |
2703 | } |
2704 | |
2705 | static inline unsigned long kvm_mmu_available_pages(struct kvm *kvm) |
2706 | { |
2707 | if (kvm->arch.n_max_mmu_pages > kvm->arch.n_used_mmu_pages) |
2708 | return kvm->arch.n_max_mmu_pages - |
2709 | kvm->arch.n_used_mmu_pages; |
2710 | |
2711 | return 0; |
2712 | } |
2713 | |
2714 | static int make_mmu_pages_available(struct kvm_vcpu *vcpu) |
2715 | { |
2716 | unsigned long avail = kvm_mmu_available_pages(kvm: vcpu->kvm); |
2717 | |
2718 | if (likely(avail >= KVM_MIN_FREE_MMU_PAGES)) |
2719 | return 0; |
2720 | |
2721 | kvm_mmu_zap_oldest_mmu_pages(kvm: vcpu->kvm, KVM_REFILL_PAGES - avail); |
2722 | |
2723 | /* |
2724 | * Note, this check is intentionally soft, it only guarantees that one |
2725 | * page is available, while the caller may end up allocating as many as |
2726 | * four pages, e.g. for PAE roots or for 5-level paging. Temporarily |
2727 | * exceeding the (arbitrary by default) limit will not harm the host, |
2728 | * being too aggressive may unnecessarily kill the guest, and getting an |
2729 | * exact count is far more trouble than it's worth, especially in the |
2730 | * page fault paths. |
2731 | */ |
2732 | if (!kvm_mmu_available_pages(kvm: vcpu->kvm)) |
2733 | return -ENOSPC; |
2734 | return 0; |
2735 | } |
2736 | |
2737 | /* |
2738 | * Changing the number of mmu pages allocated to the vm |
2739 | * Note: if goal_nr_mmu_pages is too small, you will get dead lock |
2740 | */ |
2741 | void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long goal_nr_mmu_pages) |
2742 | { |
2743 | write_lock(&kvm->mmu_lock); |
2744 | |
2745 | if (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages) { |
2746 | kvm_mmu_zap_oldest_mmu_pages(kvm, nr_to_zap: kvm->arch.n_used_mmu_pages - |
2747 | goal_nr_mmu_pages); |
2748 | |
2749 | goal_nr_mmu_pages = kvm->arch.n_used_mmu_pages; |
2750 | } |
2751 | |
2752 | kvm->arch.n_max_mmu_pages = goal_nr_mmu_pages; |
2753 | |
2754 | write_unlock(&kvm->mmu_lock); |
2755 | } |
2756 | |
2757 | int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn) |
2758 | { |
2759 | struct kvm_mmu_page *sp; |
2760 | LIST_HEAD(invalid_list); |
2761 | int r; |
2762 | |
2763 | r = 0; |
2764 | write_lock(&kvm->mmu_lock); |
2765 | for_each_gfn_valid_sp_with_gptes(kvm, sp, gfn) { |
2766 | r = 1; |
2767 | kvm_mmu_prepare_zap_page(kvm, sp, invalid_list: &invalid_list); |
2768 | } |
2769 | kvm_mmu_commit_zap_page(kvm, invalid_list: &invalid_list); |
2770 | write_unlock(&kvm->mmu_lock); |
2771 | |
2772 | return r; |
2773 | } |
2774 | |
2775 | static int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva) |
2776 | { |
2777 | gpa_t gpa; |
2778 | int r; |
2779 | |
2780 | if (vcpu->arch.mmu->root_role.direct) |
2781 | return 0; |
2782 | |
2783 | gpa = kvm_mmu_gva_to_gpa_read(vcpu, gva, NULL); |
2784 | |
2785 | r = kvm_mmu_unprotect_page(kvm: vcpu->kvm, gfn: gpa >> PAGE_SHIFT); |
2786 | |
2787 | return r; |
2788 | } |
2789 | |
2790 | static void kvm_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) |
2791 | { |
2792 | trace_kvm_mmu_unsync_page(sp); |
2793 | ++kvm->stat.mmu_unsync; |
2794 | sp->unsync = 1; |
2795 | |
2796 | kvm_mmu_mark_parents_unsync(sp); |
2797 | } |
2798 | |
2799 | /* |
2800 | * Attempt to unsync any shadow pages that can be reached by the specified gfn, |
2801 | * KVM is creating a writable mapping for said gfn. Returns 0 if all pages |
2802 | * were marked unsync (or if there is no shadow page), -EPERM if the SPTE must |
2803 | * be write-protected. |
2804 | */ |
2805 | int mmu_try_to_unsync_pages(struct kvm *kvm, const struct kvm_memory_slot *slot, |
2806 | gfn_t gfn, bool can_unsync, bool prefetch) |
2807 | { |
2808 | struct kvm_mmu_page *sp; |
2809 | bool locked = false; |
2810 | |
2811 | /* |
2812 | * Force write-protection if the page is being tracked. Note, the page |
2813 | * track machinery is used to write-protect upper-level shadow pages, |
2814 | * i.e. this guards the role.level == 4K assertion below! |
2815 | */ |
2816 | if (kvm_gfn_is_write_tracked(kvm, slot, gfn)) |
2817 | return -EPERM; |
2818 | |
2819 | /* |
2820 | * The page is not write-tracked, mark existing shadow pages unsync |
2821 | * unless KVM is synchronizing an unsync SP (can_unsync = false). In |
2822 | * that case, KVM must complete emulation of the guest TLB flush before |
2823 | * allowing shadow pages to become unsync (writable by the guest). |
2824 | */ |
2825 | for_each_gfn_valid_sp_with_gptes(kvm, sp, gfn) { |
2826 | if (!can_unsync) |
2827 | return -EPERM; |
2828 | |
2829 | if (sp->unsync) |
2830 | continue; |
2831 | |
2832 | if (prefetch) |
2833 | return -EEXIST; |
2834 | |
2835 | /* |
2836 | * TDP MMU page faults require an additional spinlock as they |
2837 | * run with mmu_lock held for read, not write, and the unsync |
2838 | * logic is not thread safe. Take the spinklock regardless of |
2839 | * the MMU type to avoid extra conditionals/parameters, there's |
2840 | * no meaningful penalty if mmu_lock is held for write. |
2841 | */ |
2842 | if (!locked) { |
2843 | locked = true; |
2844 | spin_lock(lock: &kvm->arch.mmu_unsync_pages_lock); |
2845 | |
2846 | /* |
2847 | * Recheck after taking the spinlock, a different vCPU |
2848 | * may have since marked the page unsync. A false |
2849 | * negative on the unprotected check above is not |
2850 | * possible as clearing sp->unsync _must_ hold mmu_lock |
2851 | * for write, i.e. unsync cannot transition from 1->0 |
2852 | * while this CPU holds mmu_lock for read (or write). |
2853 | */ |
2854 | if (READ_ONCE(sp->unsync)) |
2855 | continue; |
2856 | } |
2857 | |
2858 | WARN_ON_ONCE(sp->role.level != PG_LEVEL_4K); |
2859 | kvm_unsync_page(kvm, sp); |
2860 | } |
2861 | if (locked) |
2862 | spin_unlock(lock: &kvm->arch.mmu_unsync_pages_lock); |
2863 | |
2864 | /* |
2865 | * We need to ensure that the marking of unsync pages is visible |
2866 | * before the SPTE is updated to allow writes because |
2867 | * kvm_mmu_sync_roots() checks the unsync flags without holding |
2868 | * the MMU lock and so can race with this. If the SPTE was updated |
2869 | * before the page had been marked as unsync-ed, something like the |
2870 | * following could happen: |
2871 | * |
2872 | * CPU 1 CPU 2 |
2873 | * --------------------------------------------------------------------- |
2874 | * 1.2 Host updates SPTE |
2875 | * to be writable |
2876 | * 2.1 Guest writes a GPTE for GVA X. |
2877 | * (GPTE being in the guest page table shadowed |
2878 | * by the SP from CPU 1.) |
2879 | * This reads SPTE during the page table walk. |
2880 | * Since SPTE.W is read as 1, there is no |
2881 | * fault. |
2882 | * |
2883 | * 2.2 Guest issues TLB flush. |
2884 | * That causes a VM Exit. |
2885 | * |
2886 | * 2.3 Walking of unsync pages sees sp->unsync is |
2887 | * false and skips the page. |
2888 | * |
2889 | * 2.4 Guest accesses GVA X. |
2890 | * Since the mapping in the SP was not updated, |
2891 | * so the old mapping for GVA X incorrectly |
2892 | * gets used. |
2893 | * 1.1 Host marks SP |
2894 | * as unsync |
2895 | * (sp->unsync = true) |
2896 | * |
2897 | * The write barrier below ensures that 1.1 happens before 1.2 and thus |
2898 | * the situation in 2.4 does not arise. It pairs with the read barrier |
2899 | * in is_unsync_root(), placed between 2.1's load of SPTE.W and 2.3. |
2900 | */ |
2901 | smp_wmb(); |
2902 | |
2903 | return 0; |
2904 | } |
2905 | |
2906 | static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, |
2907 | u64 *sptep, unsigned int pte_access, gfn_t gfn, |
2908 | kvm_pfn_t pfn, struct kvm_page_fault *fault) |
2909 | { |
2910 | struct kvm_mmu_page *sp = sptep_to_sp(sptep); |
2911 | int level = sp->role.level; |
2912 | int was_rmapped = 0; |
2913 | int ret = RET_PF_FIXED; |
2914 | bool flush = false; |
2915 | bool wrprot; |
2916 | u64 spte; |
2917 | |
2918 | /* Prefetching always gets a writable pfn. */ |
2919 | bool host_writable = !fault || fault->map_writable; |
2920 | bool prefetch = !fault || fault->prefetch; |
2921 | bool write_fault = fault && fault->write; |
2922 | |
2923 | if (unlikely(is_noslot_pfn(pfn))) { |
2924 | vcpu->stat.pf_mmio_spte_created++; |
2925 | mark_mmio_spte(vcpu, sptep, gfn, access: pte_access); |
2926 | return RET_PF_EMULATE; |
2927 | } |
2928 | |
2929 | if (is_shadow_present_pte(pte: *sptep)) { |
2930 | /* |
2931 | * If we overwrite a PTE page pointer with a 2MB PMD, unlink |
2932 | * the parent of the now unreachable PTE. |
2933 | */ |
2934 | if (level > PG_LEVEL_4K && !is_large_pte(pte: *sptep)) { |
2935 | struct kvm_mmu_page *child; |
2936 | u64 pte = *sptep; |
2937 | |
2938 | child = spte_to_child_sp(spte: pte); |
2939 | drop_parent_pte(kvm: vcpu->kvm, sp: child, parent_pte: sptep); |
2940 | flush = true; |
2941 | } else if (pfn != spte_to_pfn(pte: *sptep)) { |
2942 | drop_spte(kvm: vcpu->kvm, sptep); |
2943 | flush = true; |
2944 | } else |
2945 | was_rmapped = 1; |
2946 | } |
2947 | |
2948 | wrprot = make_spte(vcpu, sp, slot, pte_access, gfn, pfn, old_spte: *sptep, prefetch, |
2949 | can_unsync: true, host_writable, new_spte: &spte); |
2950 | |
2951 | if (*sptep == spte) { |
2952 | ret = RET_PF_SPURIOUS; |
2953 | } else { |
2954 | flush |= mmu_spte_update(sptep, new_spte: spte); |
2955 | trace_kvm_mmu_set_spte(level, gfn, sptep); |
2956 | } |
2957 | |
2958 | if (wrprot) { |
2959 | if (write_fault) |
2960 | ret = RET_PF_EMULATE; |
2961 | } |
2962 | |
2963 | if (flush) |
2964 | kvm_flush_remote_tlbs_gfn(kvm: vcpu->kvm, gfn, level); |
2965 | |
2966 | if (!was_rmapped) { |
2967 | WARN_ON_ONCE(ret == RET_PF_SPURIOUS); |
2968 | rmap_add(vcpu, slot, spte: sptep, gfn, access: pte_access); |
2969 | } else { |
2970 | /* Already rmapped but the pte_access bits may have changed. */ |
2971 | kvm_mmu_page_set_access(sp, index: spte_index(sptep), access: pte_access); |
2972 | } |
2973 | |
2974 | return ret; |
2975 | } |
2976 | |
2977 | static int direct_pte_prefetch_many(struct kvm_vcpu *vcpu, |
2978 | struct kvm_mmu_page *sp, |
2979 | u64 *start, u64 *end) |
2980 | { |
2981 | struct page *pages[PTE_PREFETCH_NUM]; |
2982 | struct kvm_memory_slot *slot; |
2983 | unsigned int access = sp->role.access; |
2984 | int i, ret; |
2985 | gfn_t gfn; |
2986 | |
2987 | gfn = kvm_mmu_page_get_gfn(sp, index: spte_index(sptep: start)); |
2988 | slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, no_dirty_log: access & ACC_WRITE_MASK); |
2989 | if (!slot) |
2990 | return -1; |
2991 | |
2992 | ret = gfn_to_page_many_atomic(slot, gfn, pages, nr_pages: end - start); |
2993 | if (ret <= 0) |
2994 | return -1; |
2995 | |
2996 | for (i = 0; i < ret; i++, gfn++, start++) { |
2997 | mmu_set_spte(vcpu, slot, sptep: start, pte_access: access, gfn, |
2998 | page_to_pfn(pages[i]), NULL); |
2999 | put_page(page: pages[i]); |
3000 | } |
3001 | |
3002 | return 0; |
3003 | } |
3004 | |
3005 | static void __direct_pte_prefetch(struct kvm_vcpu *vcpu, |
3006 | struct kvm_mmu_page *sp, u64 *sptep) |
3007 | { |
3008 | u64 *spte, *start = NULL; |
3009 | int i; |
3010 | |
3011 | WARN_ON_ONCE(!sp->role.direct); |
3012 | |
3013 | i = spte_index(sptep) & ~(PTE_PREFETCH_NUM - 1); |
3014 | spte = sp->spt + i; |
3015 | |
3016 | for (i = 0; i < PTE_PREFETCH_NUM; i++, spte++) { |
3017 | if (is_shadow_present_pte(pte: *spte) || spte == sptep) { |
3018 | if (!start) |
3019 | continue; |
3020 | if (direct_pte_prefetch_many(vcpu, sp, start, end: spte) < 0) |
3021 | return; |
3022 | start = NULL; |
3023 | } else if (!start) |
3024 | start = spte; |
3025 | } |
3026 | if (start) |
3027 | direct_pte_prefetch_many(vcpu, sp, start, end: spte); |
3028 | } |
3029 | |
3030 | static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep) |
3031 | { |
3032 | struct kvm_mmu_page *sp; |
3033 | |
3034 | sp = sptep_to_sp(sptep); |
3035 | |
3036 | /* |
3037 | * Without accessed bits, there's no way to distinguish between |
3038 | * actually accessed translations and prefetched, so disable pte |
3039 | * prefetch if accessed bits aren't available. |
3040 | */ |
3041 | if (sp_ad_disabled(sp)) |
3042 | return; |
3043 | |
3044 | if (sp->role.level > PG_LEVEL_4K) |
3045 | return; |
3046 | |
3047 | /* |
3048 | * If addresses are being invalidated, skip prefetching to avoid |
3049 | * accidentally prefetching those addresses. |
3050 | */ |
3051 | if (unlikely(vcpu->kvm->mmu_invalidate_in_progress)) |
3052 | return; |
3053 | |
3054 | __direct_pte_prefetch(vcpu, sp, sptep); |
3055 | } |
3056 | |
3057 | /* |
3058 | * Lookup the mapping level for @gfn in the current mm. |
3059 | * |
3060 | * WARNING! Use of host_pfn_mapping_level() requires the caller and the end |
3061 | * consumer to be tied into KVM's handlers for MMU notifier events! |
3062 | * |
3063 | * There are several ways to safely use this helper: |
3064 | * |
3065 | * - Check mmu_invalidate_retry_gfn() after grabbing the mapping level, before |
3066 | * consuming it. In this case, mmu_lock doesn't need to be held during the |
3067 | * lookup, but it does need to be held while checking the MMU notifier. |
3068 | * |
3069 | * - Hold mmu_lock AND ensure there is no in-progress MMU notifier invalidation |
3070 | * event for the hva. This can be done by explicit checking the MMU notifier |
3071 | * or by ensuring that KVM already has a valid mapping that covers the hva. |
3072 | * |
3073 | * - Do not use the result to install new mappings, e.g. use the host mapping |
3074 | * level only to decide whether or not to zap an entry. In this case, it's |
3075 | * not required to hold mmu_lock (though it's highly likely the caller will |
3076 | * want to hold mmu_lock anyways, e.g. to modify SPTEs). |
3077 | * |
3078 | * Note! The lookup can still race with modifications to host page tables, but |
3079 | * the above "rules" ensure KVM will not _consume_ the result of the walk if a |
3080 | * race with the primary MMU occurs. |
3081 | */ |
3082 | static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn, |
3083 | const struct kvm_memory_slot *slot) |
3084 | { |
3085 | int level = PG_LEVEL_4K; |
3086 | unsigned long hva; |
3087 | unsigned long flags; |
3088 | pgd_t pgd; |
3089 | p4d_t p4d; |
3090 | pud_t pud; |
3091 | pmd_t pmd; |
3092 | |
3093 | /* |
3094 | * Note, using the already-retrieved memslot and __gfn_to_hva_memslot() |
3095 | * is not solely for performance, it's also necessary to avoid the |
3096 | * "writable" check in __gfn_to_hva_many(), which will always fail on |
3097 | * read-only memslots due to gfn_to_hva() assuming writes. Earlier |
3098 | * page fault steps have already verified the guest isn't writing a |
3099 | * read-only memslot. |
3100 | */ |
3101 | hva = __gfn_to_hva_memslot(slot, gfn); |
3102 | |
3103 | /* |
3104 | * Disable IRQs to prevent concurrent tear down of host page tables, |
3105 | * e.g. if the primary MMU promotes a P*D to a huge page and then frees |
3106 | * the original page table. |
3107 | */ |
3108 | local_irq_save(flags); |
3109 | |
3110 | /* |
3111 | * Read each entry once. As above, a non-leaf entry can be promoted to |
3112 | * a huge page _during_ this walk. Re-reading the entry could send the |
3113 | * walk into the weeks, e.g. p*d_leaf() returns false (sees the old |
3114 | * value) and then p*d_offset() walks into the target huge page instead |
3115 | * of the old page table (sees the new value). |
3116 | */ |
3117 | pgd = READ_ONCE(*pgd_offset(kvm->mm, hva)); |
3118 | if (pgd_none(pgd)) |
3119 | goto out; |
3120 | |
3121 | p4d = READ_ONCE(*p4d_offset(&pgd, hva)); |
3122 | if (p4d_none(p4d) || !p4d_present(p4d)) |
3123 | goto out; |
3124 | |
3125 | pud = READ_ONCE(*pud_offset(&p4d, hva)); |
3126 | if (pud_none(pud) || !pud_present(pud)) |
3127 | goto out; |
3128 | |
3129 | if (pud_leaf(pud)) { |
3130 | level = PG_LEVEL_1G; |
3131 | goto out; |
3132 | } |
3133 | |
3134 | pmd = READ_ONCE(*pmd_offset(&pud, hva)); |
3135 | if (pmd_none(pmd) || !pmd_present(pmd)) |
3136 | goto out; |
3137 | |
3138 | if (pmd_leaf(pte: pmd)) |
3139 | level = PG_LEVEL_2M; |
3140 | |
3141 | out: |
3142 | local_irq_restore(flags); |
3143 | return level; |
3144 | } |
3145 | |
3146 | static int __kvm_mmu_max_mapping_level(struct kvm *kvm, |
3147 | const struct kvm_memory_slot *slot, |
3148 | gfn_t gfn, int max_level, bool is_private) |
3149 | { |
3150 | struct kvm_lpage_info *linfo; |
3151 | int host_level; |
3152 | |
3153 | max_level = min(max_level, max_huge_page_level); |
3154 | for ( ; max_level > PG_LEVEL_4K; max_level--) { |
3155 | linfo = lpage_info_slot(gfn, slot, level: max_level); |
3156 | if (!linfo->disallow_lpage) |
3157 | break; |
3158 | } |
3159 | |
3160 | if (is_private) |
3161 | return max_level; |
3162 | |
3163 | if (max_level == PG_LEVEL_4K) |
3164 | return PG_LEVEL_4K; |
3165 | |
3166 | host_level = host_pfn_mapping_level(kvm, gfn, slot); |
3167 | return min(host_level, max_level); |
3168 | } |
3169 | |
3170 | int kvm_mmu_max_mapping_level(struct kvm *kvm, |
3171 | const struct kvm_memory_slot *slot, gfn_t gfn, |
3172 | int max_level) |
3173 | { |
3174 | bool is_private = kvm_slot_can_be_private(slot) && |
3175 | kvm_mem_is_private(kvm, gfn); |
3176 | |
3177 | return __kvm_mmu_max_mapping_level(kvm, slot, gfn, max_level, is_private); |
3178 | } |
3179 | |
3180 | void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) |
3181 | { |
3182 | struct kvm_memory_slot *slot = fault->slot; |
3183 | kvm_pfn_t mask; |
3184 | |
3185 | fault->huge_page_disallowed = fault->exec && fault->nx_huge_page_workaround_enabled; |
3186 | |
3187 | if (unlikely(fault->max_level == PG_LEVEL_4K)) |
3188 | return; |
3189 | |
3190 | if (is_error_noslot_pfn(pfn: fault->pfn)) |
3191 | return; |
3192 | |
3193 | if (kvm_slot_dirty_track_enabled(slot)) |
3194 | return; |
3195 | |
3196 | /* |
3197 | * Enforce the iTLB multihit workaround after capturing the requested |
3198 | * level, which will be used to do precise, accurate accounting. |
3199 | */ |
3200 | fault->req_level = __kvm_mmu_max_mapping_level(kvm: vcpu->kvm, slot, |
3201 | gfn: fault->gfn, max_level: fault->max_level, |
3202 | is_private: fault->is_private); |
3203 | if (fault->req_level == PG_LEVEL_4K || fault->huge_page_disallowed) |
3204 | return; |
3205 | |
3206 | /* |
3207 | * mmu_invalidate_retry() was successful and mmu_lock is held, so |
3208 | * the pmd can't be split from under us. |
3209 | */ |
3210 | fault->goal_level = fault->req_level; |
3211 | mask = KVM_PAGES_PER_HPAGE(fault->goal_level) - 1; |
3212 | VM_BUG_ON((fault->gfn & mask) != (fault->pfn & mask)); |
3213 | fault->pfn &= ~mask; |
3214 | } |
3215 | |
3216 | void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_level) |
3217 | { |
3218 | if (cur_level > PG_LEVEL_4K && |
3219 | cur_level == fault->goal_level && |
3220 | is_shadow_present_pte(pte: spte) && |
3221 | !is_large_pte(pte: spte) && |
3222 | spte_to_child_sp(spte)->nx_huge_page_disallowed) { |
3223 | /* |
3224 | * A small SPTE exists for this pfn, but FNAME(fetch), |
3225 | * direct_map(), or kvm_tdp_mmu_map() would like to create a |
3226 | * large PTE instead: just force them to go down another level, |
3227 | * patching back for them into pfn the next 9 bits of the |
3228 | * address. |
3229 | */ |
3230 | u64 page_mask = KVM_PAGES_PER_HPAGE(cur_level) - |
3231 | KVM_PAGES_PER_HPAGE(cur_level - 1); |
3232 | fault->pfn |= fault->gfn & page_mask; |
3233 | fault->goal_level--; |
3234 | } |
3235 | } |
3236 | |
3237 | static int direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) |
3238 | { |
3239 | struct kvm_shadow_walk_iterator it; |
3240 | struct kvm_mmu_page *sp; |
3241 | int ret; |
3242 | gfn_t base_gfn = fault->gfn; |
3243 | |
3244 | kvm_mmu_hugepage_adjust(vcpu, fault); |
3245 | |
3246 | trace_kvm_mmu_spte_requested(fault); |
3247 | for_each_shadow_entry(vcpu, fault->addr, it) { |
3248 | /* |
3249 | * We cannot overwrite existing page tables with an NX |
3250 | * large page, as the leaf could be executable. |
3251 | */ |
3252 | if (fault->nx_huge_page_workaround_enabled) |
3253 | disallowed_hugepage_adjust(fault, spte: *it.sptep, cur_level: it.level); |
3254 | |
3255 | base_gfn = gfn_round_for_level(gfn: fault->gfn, level: it.level); |
3256 | if (it.level == fault->goal_level) |
3257 | break; |
3258 | |
3259 | sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn, true, ACC_ALL); |
3260 | if (sp == ERR_PTR(error: -EEXIST)) |
3261 | continue; |
3262 | |
3263 | link_shadow_page(vcpu, sptep: it.sptep, sp); |
3264 | if (fault->huge_page_disallowed) |
3265 | account_nx_huge_page(kvm: vcpu->kvm, sp, |
3266 | nx_huge_page_possible: fault->req_level >= it.level); |
3267 | } |
3268 | |
3269 | if (WARN_ON_ONCE(it.level != fault->goal_level)) |
3270 | return -EFAULT; |
3271 | |
3272 | ret = mmu_set_spte(vcpu, fault->slot, it.sptep, ACC_ALL, |
3273 | base_gfn, fault->pfn, fault); |
3274 | if (ret == RET_PF_SPURIOUS) |
3275 | return ret; |
3276 | |
3277 | direct_pte_prefetch(vcpu, sptep: it.sptep); |
3278 | return ret; |
3279 | } |
3280 | |
3281 | static void kvm_send_hwpoison_signal(struct kvm_memory_slot *slot, gfn_t gfn) |
3282 | { |
3283 | unsigned long hva = gfn_to_hva_memslot(slot, gfn); |
3284 | |
3285 | send_sig_mceerr(BUS_MCEERR_AR, (void __user *)hva, PAGE_SHIFT, current); |
3286 | } |
3287 | |
3288 | static int kvm_handle_error_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) |
3289 | { |
3290 | if (is_sigpending_pfn(pfn: fault->pfn)) { |
3291 | kvm_handle_signal_exit(vcpu); |
3292 | return -EINTR; |
3293 | } |
3294 | |
3295 | /* |
3296 | * Do not cache the mmio info caused by writing the readonly gfn |
3297 | * into the spte otherwise read access on readonly gfn also can |
3298 | * caused mmio page fault and treat it as mmio access. |
3299 | */ |
3300 | if (fault->pfn == KVM_PFN_ERR_RO_FAULT) |
3301 | return RET_PF_EMULATE; |
3302 | |
3303 | if (fault->pfn == KVM_PFN_ERR_HWPOISON) { |
3304 | kvm_send_hwpoison_signal(slot: fault->slot, gfn: fault->gfn); |
3305 | return RET_PF_RETRY; |
3306 | } |
3307 | |
3308 | return -EFAULT; |
3309 | } |
3310 | |
3311 | static int kvm_handle_noslot_fault(struct kvm_vcpu *vcpu, |
3312 | struct kvm_page_fault *fault, |
3313 | unsigned int access) |
3314 | { |
3315 | gva_t gva = fault->is_tdp ? 0 : fault->addr; |
3316 | |
3317 | vcpu_cache_mmio_info(vcpu, gva, fault->gfn, |
3318 | access & shadow_mmio_access_mask); |
3319 | |
3320 | /* |
3321 | * If MMIO caching is disabled, emulate immediately without |
3322 | * touching the shadow page tables as attempting to install an |
3323 | * MMIO SPTE will just be an expensive nop. |
3324 | */ |
3325 | if (unlikely(!enable_mmio_caching)) |
3326 | return RET_PF_EMULATE; |
3327 | |
3328 | /* |
3329 | * Do not create an MMIO SPTE for a gfn greater than host.MAXPHYADDR, |
3330 | * any guest that generates such gfns is running nested and is being |
3331 | * tricked by L0 userspace (you can observe gfn > L1.MAXPHYADDR if and |
3332 | * only if L1's MAXPHYADDR is inaccurate with respect to the |
3333 | * hardware's). |
3334 | */ |
3335 | if (unlikely(fault->gfn > kvm_mmu_max_gfn())) |
3336 | return RET_PF_EMULATE; |
3337 | |
3338 | return RET_PF_CONTINUE; |
3339 | } |
3340 | |
3341 | static bool page_fault_can_be_fast(struct kvm_page_fault *fault) |
3342 | { |
3343 | /* |
3344 | * Page faults with reserved bits set, i.e. faults on MMIO SPTEs, only |
3345 | * reach the common page fault handler if the SPTE has an invalid MMIO |
3346 | * generation number. Refreshing the MMIO generation needs to go down |
3347 | * the slow path. Note, EPT Misconfigs do NOT set the PRESENT flag! |
3348 | */ |
3349 | if (fault->rsvd) |
3350 | return false; |
3351 | |
3352 | /* |
3353 | * #PF can be fast if: |
3354 | * |
3355 | * 1. The shadow page table entry is not present and A/D bits are |
3356 | * disabled _by KVM_, which could mean that the fault is potentially |
3357 | * caused by access tracking (if enabled). If A/D bits are enabled |
3358 | * by KVM, but disabled by L1 for L2, KVM is forced to disable A/D |
3359 | * bits for L2 and employ access tracking, but the fast page fault |
3360 | * mechanism only supports direct MMUs. |
3361 | * 2. The shadow page table entry is present, the access is a write, |
3362 | * and no reserved bits are set (MMIO SPTEs cannot be "fixed"), i.e. |
3363 | * the fault was caused by a write-protection violation. If the |
3364 | * SPTE is MMU-writable (determined later), the fault can be fixed |
3365 | * by setting the Writable bit, which can be done out of mmu_lock. |
3366 | */ |
3367 | if (!fault->present) |
3368 | return !kvm_ad_enabled(); |
3369 | |
3370 | /* |
3371 | * Note, instruction fetches and writes are mutually exclusive, ignore |
3372 | * the "exec" flag. |
3373 | */ |
3374 | return fault->write; |
3375 | } |
3376 | |
3377 | /* |
3378 | * Returns true if the SPTE was fixed successfully. Otherwise, |
3379 | * someone else modified the SPTE from its original value. |
3380 | */ |
3381 | static bool fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, |
3382 | struct kvm_page_fault *fault, |
3383 | u64 *sptep, u64 old_spte, u64 new_spte) |
3384 | { |
3385 | /* |
3386 | * Theoretically we could also set dirty bit (and flush TLB) here in |
3387 | * order to eliminate unnecessary PML logging. See comments in |
3388 | * set_spte. But fast_page_fault is very unlikely to happen with PML |
3389 | * enabled, so we do not do this. This might result in the same GPA |
3390 | * to be logged in PML buffer again when the write really happens, and |
3391 | * eventually to be called by mark_page_dirty twice. But it's also no |
3392 | * harm. This also avoids the TLB flush needed after setting dirty bit |
3393 | * so non-PML cases won't be impacted. |
3394 | * |
3395 | * Compare with set_spte where instead shadow_dirty_mask is set. |
3396 | */ |
3397 | if (!try_cmpxchg64(sptep, &old_spte, new_spte)) |
3398 | return false; |
3399 | |
3400 | if (is_writable_pte(pte: new_spte) && !is_writable_pte(pte: old_spte)) |
3401 | mark_page_dirty_in_slot(kvm: vcpu->kvm, memslot: fault->slot, gfn: fault->gfn); |
3402 | |
3403 | return true; |
3404 | } |
3405 | |
3406 | static bool is_access_allowed(struct kvm_page_fault *fault, u64 spte) |
3407 | { |
3408 | if (fault->exec) |
3409 | return is_executable_pte(spte); |
3410 | |
3411 | if (fault->write) |
3412 | return is_writable_pte(pte: spte); |
3413 | |
3414 | /* Fault was on Read access */ |
3415 | return spte & PT_PRESENT_MASK; |
3416 | } |
3417 | |
3418 | /* |
3419 | * Returns the last level spte pointer of the shadow page walk for the given |
3420 | * gpa, and sets *spte to the spte value. This spte may be non-preset. If no |
3421 | * walk could be performed, returns NULL and *spte does not contain valid data. |
3422 | * |
3423 | * Contract: |
3424 | * - Must be called between walk_shadow_page_lockless_{begin,end}. |
3425 | * - The returned sptep must not be used after walk_shadow_page_lockless_end. |
3426 | */ |
3427 | static u64 *fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, gpa_t gpa, u64 *spte) |
3428 | { |
3429 | struct kvm_shadow_walk_iterator iterator; |
3430 | u64 old_spte; |
3431 | u64 *sptep = NULL; |
3432 | |
3433 | for_each_shadow_entry_lockless(vcpu, gpa, iterator, old_spte) { |
3434 | sptep = iterator.sptep; |
3435 | *spte = old_spte; |
3436 | } |
3437 | |
3438 | return sptep; |
3439 | } |
3440 | |
3441 | /* |
3442 | * Returns one of RET_PF_INVALID, RET_PF_FIXED or RET_PF_SPURIOUS. |
3443 | */ |
3444 | static int fast_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) |
3445 | { |
3446 | struct kvm_mmu_page *sp; |
3447 | int ret = RET_PF_INVALID; |
3448 | u64 spte; |
3449 | u64 *sptep; |
3450 | uint retry_count = 0; |
3451 | |
3452 | if (!page_fault_can_be_fast(fault)) |
3453 | return ret; |
3454 | |
3455 | walk_shadow_page_lockless_begin(vcpu); |
3456 | |
3457 | do { |
3458 | u64 new_spte; |
3459 | |
3460 | if (tdp_mmu_enabled) |
3461 | sptep = kvm_tdp_mmu_fast_pf_get_last_sptep(vcpu, addr: fault->addr, spte: &spte); |
3462 | else |
3463 | sptep = fast_pf_get_last_sptep(vcpu, gpa: fault->addr, spte: &spte); |
3464 | |
3465 | /* |
3466 | * It's entirely possible for the mapping to have been zapped |
3467 | * by a different task, but the root page should always be |
3468 | * available as the vCPU holds a reference to its root(s). |
3469 | */ |
3470 | if (WARN_ON_ONCE(!sptep)) |
3471 | spte = REMOVED_SPTE; |
3472 | |
3473 | if (!is_shadow_present_pte(pte: spte)) |
3474 | break; |
3475 | |
3476 | sp = sptep_to_sp(sptep); |
3477 | if (!is_last_spte(pte: spte, level: sp->role.level)) |
3478 | break; |
3479 | |
3480 | /* |
3481 | * Check whether the memory access that caused the fault would |
3482 | * still cause it if it were to be performed right now. If not, |
3483 | * then this is a spurious fault caused by TLB lazily flushed, |
3484 | * or some other CPU has already fixed the PTE after the |
3485 | * current CPU took the fault. |
3486 | * |
3487 | * Need not check the access of upper level table entries since |
3488 | * they are always ACC_ALL. |
3489 | */ |
3490 | if (is_access_allowed(fault, spte)) { |
3491 | ret = RET_PF_SPURIOUS; |
3492 | break; |
3493 | } |
3494 | |
3495 | new_spte = spte; |
3496 | |
3497 | /* |
3498 | * KVM only supports fixing page faults outside of MMU lock for |
3499 | * direct MMUs, nested MMUs are always indirect, and KVM always |
3500 | * uses A/D bits for non-nested MMUs. Thus, if A/D bits are |
3501 | * enabled, the SPTE can't be an access-tracked SPTE. |
3502 | */ |
3503 | if (unlikely(!kvm_ad_enabled()) && is_access_track_spte(spte)) |
3504 | new_spte = restore_acc_track_spte(spte: new_spte); |
3505 | |
3506 | /* |
3507 | * To keep things simple, only SPTEs that are MMU-writable can |
3508 | * be made fully writable outside of mmu_lock, e.g. only SPTEs |
3509 | * that were write-protected for dirty-logging or access |
3510 | * tracking are handled here. Don't bother checking if the |
3511 | * SPTE is writable to prioritize running with A/D bits enabled. |
3512 | * The is_access_allowed() check above handles the common case |
3513 | * of the fault being spurious, and the SPTE is known to be |
3514 | * shadow-present, i.e. except for access tracking restoration |
3515 | * making the new SPTE writable, the check is wasteful. |
3516 | */ |
3517 | if (fault->write && is_mmu_writable_spte(spte)) { |
3518 | new_spte |= PT_WRITABLE_MASK; |
3519 | |
3520 | /* |
3521 | * Do not fix write-permission on the large spte when |
3522 | * dirty logging is enabled. Since we only dirty the |
3523 | * first page into the dirty-bitmap in |
3524 | * fast_pf_fix_direct_spte(), other pages are missed |
3525 | * if its slot has dirty logging enabled. |
3526 | * |
3527 | * Instead, we let the slow page fault path create a |
3528 | * normal spte to fix the access. |
3529 | */ |
3530 | if (sp->role.level > PG_LEVEL_4K && |
3531 | kvm_slot_dirty_track_enabled(slot: fault->slot)) |
3532 | break; |
3533 | } |
3534 | |
3535 | /* Verify that the fault can be handled in the fast path */ |
3536 | if (new_spte == spte || |
3537 | !is_access_allowed(fault, spte: new_spte)) |
3538 | break; |
3539 | |
3540 | /* |
3541 | * Currently, fast page fault only works for direct mapping |
3542 | * since the gfn is not stable for indirect shadow page. See |
3543 | * Documentation/virt/kvm/locking.rst to get more detail. |
3544 | */ |
3545 | if (fast_pf_fix_direct_spte(vcpu, fault, sptep, old_spte: spte, new_spte)) { |
3546 | ret = RET_PF_FIXED; |
3547 | break; |
3548 | } |
3549 | |
3550 | if (++retry_count > 4) { |
3551 | pr_warn_once("Fast #PF retrying more than 4 times.\n" ); |
3552 | break; |
3553 | } |
3554 | |
3555 | } while (true); |
3556 | |
3557 | trace_fast_page_fault(vcpu, fault, sptep, old_spte: spte, ret); |
3558 | walk_shadow_page_lockless_end(vcpu); |
3559 | |
3560 | if (ret != RET_PF_INVALID) |
3561 | vcpu->stat.pf_fast++; |
3562 | |
3563 | return ret; |
3564 | } |
3565 | |
3566 | static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa, |
3567 | struct list_head *invalid_list) |
3568 | { |
3569 | struct kvm_mmu_page *sp; |
3570 | |
3571 | if (!VALID_PAGE(*root_hpa)) |
3572 | return; |
3573 | |
3574 | sp = root_to_sp(root: *root_hpa); |
3575 | if (WARN_ON_ONCE(!sp)) |
3576 | return; |
3577 | |
3578 | if (is_tdp_mmu_page(sp)) { |
3579 | lockdep_assert_held_read(&kvm->mmu_lock); |
3580 | kvm_tdp_mmu_put_root(kvm, root: sp); |
3581 | } else { |
3582 | lockdep_assert_held_write(&kvm->mmu_lock); |
3583 | if (!--sp->root_count && sp->role.invalid) |
3584 | kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); |
3585 | } |
3586 | |
3587 | *root_hpa = INVALID_PAGE; |
3588 | } |
3589 | |
3590 | /* roots_to_free must be some combination of the KVM_MMU_ROOT_* flags */ |
3591 | void kvm_mmu_free_roots(struct kvm *kvm, struct kvm_mmu *mmu, |
3592 | ulong roots_to_free) |
3593 | { |
3594 | bool is_tdp_mmu = tdp_mmu_enabled && mmu->root_role.direct; |
3595 | int i; |
3596 | LIST_HEAD(invalid_list); |
3597 | bool free_active_root; |
3598 | |
3599 | WARN_ON_ONCE(roots_to_free & ~KVM_MMU_ROOTS_ALL); |
3600 | |
3601 | BUILD_BUG_ON(KVM_MMU_NUM_PREV_ROOTS >= BITS_PER_LONG); |
3602 | |
3603 | /* Before acquiring the MMU lock, see if we need to do any real work. */ |
3604 | free_active_root = (roots_to_free & KVM_MMU_ROOT_CURRENT) |
3605 | && VALID_PAGE(mmu->root.hpa); |
3606 | |
3607 | if (!free_active_root) { |
3608 | for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) |
3609 | if ((roots_to_free & KVM_MMU_ROOT_PREVIOUS(i)) && |
3610 | VALID_PAGE(mmu->prev_roots[i].hpa)) |
3611 | break; |
3612 | |
3613 | if (i == KVM_MMU_NUM_PREV_ROOTS) |
3614 | return; |
3615 | } |
3616 | |
3617 | if (is_tdp_mmu) |
3618 | read_lock(&kvm->mmu_lock); |
3619 | else |
3620 | write_lock(&kvm->mmu_lock); |
3621 | |
3622 | for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) |
3623 | if (roots_to_free & KVM_MMU_ROOT_PREVIOUS(i)) |
3624 | mmu_free_root_page(kvm, root_hpa: &mmu->prev_roots[i].hpa, |
3625 | invalid_list: &invalid_list); |
3626 | |
3627 | if (free_active_root) { |
3628 | if (kvm_mmu_is_dummy_root(shadow_page: mmu->root.hpa)) { |
3629 | /* Nothing to cleanup for dummy roots. */ |
3630 | } else if (root_to_sp(root: mmu->root.hpa)) { |
3631 | mmu_free_root_page(kvm, root_hpa: &mmu->root.hpa, invalid_list: &invalid_list); |
3632 | } else if (mmu->pae_root) { |
3633 | for (i = 0; i < 4; ++i) { |
3634 | if (!IS_VALID_PAE_ROOT(mmu->pae_root[i])) |
3635 | continue; |
3636 | |
3637 | mmu_free_root_page(kvm, root_hpa: &mmu->pae_root[i], |
3638 | invalid_list: &invalid_list); |
3639 | mmu->pae_root[i] = INVALID_PAE_ROOT; |
3640 | } |
3641 | } |
3642 | mmu->root.hpa = INVALID_PAGE; |
3643 | mmu->root.pgd = 0; |
3644 | } |
3645 | |
3646 | if (is_tdp_mmu) { |
3647 | read_unlock(&kvm->mmu_lock); |
3648 | WARN_ON_ONCE(!list_empty(&invalid_list)); |
3649 | } else { |
3650 | kvm_mmu_commit_zap_page(kvm, invalid_list: &invalid_list); |
3651 | write_unlock(&kvm->mmu_lock); |
3652 | } |
3653 | } |
3654 | EXPORT_SYMBOL_GPL(kvm_mmu_free_roots); |
3655 | |
3656 | void kvm_mmu_free_guest_mode_roots(struct kvm *kvm, struct kvm_mmu *mmu) |
3657 | { |
3658 | unsigned long roots_to_free = 0; |
3659 | struct kvm_mmu_page *sp; |
3660 | hpa_t root_hpa; |
3661 | int i; |
3662 | |
3663 | /* |
3664 | * This should not be called while L2 is active, L2 can't invalidate |
3665 | * _only_ its own roots, e.g. INVVPID unconditionally exits. |
3666 | */ |
3667 | WARN_ON_ONCE(mmu->root_role.guest_mode); |
3668 | |
3669 | for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { |
3670 | root_hpa = mmu->prev_roots[i].hpa; |
3671 | if (!VALID_PAGE(root_hpa)) |
3672 | continue; |
3673 | |
3674 | sp = root_to_sp(root: root_hpa); |
3675 | if (!sp || sp->role.guest_mode) |
3676 | roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); |
3677 | } |
3678 | |
3679 | kvm_mmu_free_roots(kvm, mmu, roots_to_free); |
3680 | } |
3681 | EXPORT_SYMBOL_GPL(kvm_mmu_free_guest_mode_roots); |
3682 | |
3683 | static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant, |
3684 | u8 level) |
3685 | { |
3686 | union kvm_mmu_page_role role = vcpu->arch.mmu->root_role; |
3687 | struct kvm_mmu_page *sp; |
3688 | |
3689 | role.level = level; |
3690 | role.quadrant = quadrant; |
3691 | |
3692 | WARN_ON_ONCE(quadrant && !role.has_4_byte_gpte); |
3693 | WARN_ON_ONCE(role.direct && role.has_4_byte_gpte); |
3694 | |
3695 | sp = kvm_mmu_get_shadow_page(vcpu, gfn, role); |
3696 | ++sp->root_count; |
3697 | |
3698 | return __pa(sp->spt); |
3699 | } |
3700 | |
3701 | static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) |
3702 | { |
3703 | struct kvm_mmu *mmu = vcpu->arch.mmu; |
3704 | u8 shadow_root_level = mmu->root_role.level; |
3705 | hpa_t root; |
3706 | unsigned i; |
3707 | int r; |
3708 | |
3709 | if (tdp_mmu_enabled) |
3710 | return kvm_tdp_mmu_alloc_root(vcpu); |
3711 | |
3712 | write_lock(&vcpu->kvm->mmu_lock); |
3713 | r = make_mmu_pages_available(vcpu); |
3714 | if (r < 0) |
3715 | goto out_unlock; |
3716 | |
3717 | if (shadow_root_level >= PT64_ROOT_4LEVEL) { |
3718 | root = mmu_alloc_root(vcpu, gfn: 0, quadrant: 0, level: shadow_root_level); |
3719 | mmu->root.hpa = root; |
3720 | } else if (shadow_root_level == PT32E_ROOT_LEVEL) { |
3721 | if (WARN_ON_ONCE(!mmu->pae_root)) { |
3722 | r = -EIO; |
3723 | goto out_unlock; |
3724 | } |
3725 | |
3726 | for (i = 0; i < 4; ++i) { |
3727 | WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i])); |
3728 | |
3729 | root = mmu_alloc_root(vcpu, gfn: i << (30 - PAGE_SHIFT), quadrant: 0, |
3730 | level: PT32_ROOT_LEVEL); |
3731 | mmu->pae_root[i] = root | PT_PRESENT_MASK | |
3732 | shadow_me_value; |
3733 | } |
3734 | mmu->root.hpa = __pa(mmu->pae_root); |
3735 | } else { |
3736 | WARN_ONCE(1, "Bad TDP root level = %d\n" , shadow_root_level); |
3737 | r = -EIO; |
3738 | goto out_unlock; |
3739 | } |
3740 | |
3741 | /* root.pgd is ignored for direct MMUs. */ |
3742 | mmu->root.pgd = 0; |
3743 | out_unlock: |
3744 | write_unlock(&vcpu->kvm->mmu_lock); |
3745 | return r; |
3746 | } |
3747 | |
3748 | static int mmu_first_shadow_root_alloc(struct kvm *kvm) |
3749 | { |
3750 | struct kvm_memslots *slots; |
3751 | struct kvm_memory_slot *slot; |
3752 | int r = 0, i, bkt; |
3753 | |
3754 | /* |
3755 | * Check if this is the first shadow root being allocated before |
3756 | * taking the lock. |
3757 | */ |
3758 | if (kvm_shadow_root_allocated(kvm)) |
3759 | return 0; |
3760 | |
3761 | mutex_lock(&kvm->slots_arch_lock); |
3762 | |
3763 | /* Recheck, under the lock, whether this is the first shadow root. */ |
3764 | if (kvm_shadow_root_allocated(kvm)) |
3765 | goto out_unlock; |
3766 | |
3767 | /* |
3768 | * Check if anything actually needs to be allocated, e.g. all metadata |
3769 | * will be allocated upfront if TDP is disabled. |
3770 | */ |
3771 | if (kvm_memslots_have_rmaps(kvm) && |
3772 | kvm_page_track_write_tracking_enabled(kvm)) |
3773 | goto out_success; |
3774 | |
3775 | for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) { |
3776 | slots = __kvm_memslots(kvm, as_id: i); |
3777 | kvm_for_each_memslot(slot, bkt, slots) { |
3778 | /* |
3779 | * Both of these functions are no-ops if the target is |
3780 | * already allocated, so unconditionally calling both |
3781 | * is safe. Intentionally do NOT free allocations on |
3782 | * failure to avoid having to track which allocations |
3783 | * were made now versus when the memslot was created. |
3784 | * The metadata is guaranteed to be freed when the slot |
3785 | * is freed, and will be kept/used if userspace retries |
3786 | * KVM_RUN instead of killing the VM. |
3787 | */ |
3788 | r = memslot_rmap_alloc(slot, npages: slot->npages); |
3789 | if (r) |
3790 | goto out_unlock; |
3791 | r = kvm_page_track_write_tracking_alloc(slot); |
3792 | if (r) |
3793 | goto out_unlock; |
3794 | } |
3795 | } |
3796 | |
3797 | /* |
3798 | * Ensure that shadow_root_allocated becomes true strictly after |
3799 | * all the related pointers are set. |
3800 | */ |
3801 | out_success: |
3802 | smp_store_release(&kvm->arch.shadow_root_allocated, true); |
3803 | |
3804 | out_unlock: |
3805 | mutex_unlock(lock: &kvm->slots_arch_lock); |
3806 | return r; |
3807 | } |
3808 | |
3809 | static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) |
3810 | { |
3811 | struct kvm_mmu *mmu = vcpu->arch.mmu; |
3812 | u64 pdptrs[4], pm_mask; |
3813 | gfn_t root_gfn, root_pgd; |
3814 | int quadrant, i, r; |
3815 | hpa_t root; |
3816 | |
3817 | root_pgd = kvm_mmu_get_guest_pgd(vcpu, mmu); |
3818 | root_gfn = (root_pgd & __PT_BASE_ADDR_MASK) >> PAGE_SHIFT; |
3819 | |
3820 | if (!kvm_vcpu_is_visible_gfn(vcpu, gfn: root_gfn)) { |
3821 | mmu->root.hpa = kvm_mmu_get_dummy_root(); |
3822 | return 0; |
3823 | } |
3824 | |
3825 | /* |
3826 | * On SVM, reading PDPTRs might access guest memory, which might fault |
3827 | * and thus might sleep. Grab the PDPTRs before acquiring mmu_lock. |
3828 | */ |
3829 | if (mmu->cpu_role.base.level == PT32E_ROOT_LEVEL) { |
3830 | for (i = 0; i < 4; ++i) { |
3831 | pdptrs[i] = mmu->get_pdptr(vcpu, i); |
3832 | if (!(pdptrs[i] & PT_PRESENT_MASK)) |
3833 | continue; |
3834 | |
3835 | if (!kvm_vcpu_is_visible_gfn(vcpu, gfn: pdptrs[i] >> PAGE_SHIFT)) |
3836 | pdptrs[i] = 0; |
3837 | } |
3838 | } |
3839 | |
3840 | r = mmu_first_shadow_root_alloc(kvm: vcpu->kvm); |
3841 | if (r) |
3842 | return r; |
3843 | |
3844 | write_lock(&vcpu->kvm->mmu_lock); |
3845 | r = make_mmu_pages_available(vcpu); |
3846 | if (r < 0) |
3847 | goto out_unlock; |
3848 | |
3849 | /* |
3850 | * Do we shadow a long mode page table? If so we need to |
3851 | * write-protect the guests page table root. |
3852 | */ |
3853 | if (mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL) { |
3854 | root = mmu_alloc_root(vcpu, gfn: root_gfn, quadrant: 0, |
3855 | level: mmu->root_role.level); |
3856 | mmu->root.hpa = root; |
3857 | goto set_root_pgd; |
3858 | } |
3859 | |
3860 | if (WARN_ON_ONCE(!mmu->pae_root)) { |
3861 | r = -EIO; |
3862 | goto out_unlock; |
3863 | } |
3864 | |
3865 | /* |
3866 | * We shadow a 32 bit page table. This may be a legacy 2-level |
3867 | * or a PAE 3-level page table. In either case we need to be aware that |
3868 | * the shadow page table may be a PAE or a long mode page table. |
3869 | */ |
3870 | pm_mask = PT_PRESENT_MASK | shadow_me_value; |
3871 | if (mmu->root_role.level >= PT64_ROOT_4LEVEL) { |
3872 | pm_mask |= PT_ACCESSED_MASK | PT_WRITABLE_MASK | PT_USER_MASK; |
3873 | |
3874 | if (WARN_ON_ONCE(!mmu->pml4_root)) { |
3875 | r = -EIO; |
3876 | goto out_unlock; |
3877 | } |
3878 | mmu->pml4_root[0] = __pa(mmu->pae_root) | pm_mask; |
3879 | |
3880 | if (mmu->root_role.level == PT64_ROOT_5LEVEL) { |
3881 | if (WARN_ON_ONCE(!mmu->pml5_root)) { |
3882 | r = -EIO; |
3883 | goto out_unlock; |
3884 | } |
3885 | mmu->pml5_root[0] = __pa(mmu->pml4_root) | pm_mask; |
3886 | } |
3887 | } |
3888 | |
3889 | for (i = 0; i < 4; ++i) { |
3890 | WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i])); |
3891 | |
3892 | if (mmu->cpu_role.base.level == PT32E_ROOT_LEVEL) { |
3893 | if (!(pdptrs[i] & PT_PRESENT_MASK)) { |
3894 | mmu->pae_root[i] = INVALID_PAE_ROOT; |
3895 | continue; |
3896 | } |
3897 | root_gfn = pdptrs[i] >> PAGE_SHIFT; |
3898 | } |
3899 | |
3900 | /* |
3901 | * If shadowing 32-bit non-PAE page tables, each PAE page |
3902 | * directory maps one quarter of the guest's non-PAE page |
3903 | * directory. Othwerise each PAE page direct shadows one guest |
3904 | * PAE page directory so that quadrant should be 0. |
3905 | */ |
3906 | quadrant = (mmu->cpu_role.base.level == PT32_ROOT_LEVEL) ? i : 0; |
3907 | |
3908 | root = mmu_alloc_root(vcpu, root_gfn, quadrant, PT32_ROOT_LEVEL); |
3909 | mmu->pae_root[i] = root | pm_mask; |
3910 | } |
3911 | |
3912 | if (mmu->root_role.level == PT64_ROOT_5LEVEL) |
3913 | mmu->root.hpa = __pa(mmu->pml5_root); |
3914 | else if (mmu->root_role.level == PT64_ROOT_4LEVEL) |
3915 | mmu->root.hpa = __pa(mmu->pml4_root); |
3916 | else |
3917 | mmu->root.hpa = __pa(mmu->pae_root); |
3918 | |
3919 | set_root_pgd: |
3920 | mmu->root.pgd = root_pgd; |
3921 | out_unlock: |
3922 | write_unlock(&vcpu->kvm->mmu_lock); |
3923 | |
3924 | return r; |
3925 | } |
3926 | |
3927 | static int mmu_alloc_special_roots(struct kvm_vcpu *vcpu) |
3928 | { |
3929 | struct kvm_mmu *mmu = vcpu->arch.mmu; |
3930 | bool need_pml5 = mmu->root_role.level > PT64_ROOT_4LEVEL; |
3931 | u64 *pml5_root = NULL; |
3932 | u64 *pml4_root = NULL; |
3933 | u64 *pae_root; |
3934 | |
3935 | /* |
3936 | * When shadowing 32-bit or PAE NPT with 64-bit NPT, the PML4 and PDP |
3937 | * tables are allocated and initialized at root creation as there is no |
3938 | * equivalent level in the guest's NPT to shadow. Allocate the tables |
3939 | * on demand, as running a 32-bit L1 VMM on 64-bit KVM is very rare. |
3940 | */ |
3941 | if (mmu->root_role.direct || |
3942 | mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL || |
3943 | mmu->root_role.level < PT64_ROOT_4LEVEL) |
3944 | return 0; |
3945 | |
3946 | /* |
3947 | * NPT, the only paging mode that uses this horror, uses a fixed number |
3948 | * of levels for the shadow page tables, e.g. all MMUs are 4-level or |
3949 | * all MMus are 5-level. Thus, this can safely require that pml5_root |
3950 | * is allocated if the other roots are valid and pml5 is needed, as any |
3951 | * prior MMU would also have required pml5. |
3952 | */ |
3953 | if (mmu->pae_root && mmu->pml4_root && (!need_pml5 || mmu->pml5_root)) |
3954 | return 0; |
3955 | |
3956 | /* |
3957 | * The special roots should always be allocated in concert. Yell and |
3958 | * bail if KVM ends up in a state where only one of the roots is valid. |
3959 | */ |
3960 | if (WARN_ON_ONCE(!tdp_enabled || mmu->pae_root || mmu->pml4_root || |
3961 | (need_pml5 && mmu->pml5_root))) |
3962 | return -EIO; |
3963 | |
3964 | /* |
3965 | * Unlike 32-bit NPT, the PDP table doesn't need to be in low mem, and |
3966 | * doesn't need to be decrypted. |
3967 | */ |
3968 | pae_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); |
3969 | if (!pae_root) |
3970 | return -ENOMEM; |
3971 | |
3972 | #ifdef CONFIG_X86_64 |
3973 | pml4_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); |
3974 | if (!pml4_root) |
3975 | goto err_pml4; |
3976 | |
3977 | if (need_pml5) { |
3978 | pml5_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); |
3979 | if (!pml5_root) |
3980 | goto err_pml5; |
3981 | } |
3982 | #endif |
3983 | |
3984 | mmu->pae_root = pae_root; |
3985 | mmu->pml4_root = pml4_root; |
3986 | mmu->pml5_root = pml5_root; |
3987 | |
3988 | return 0; |
3989 | |
3990 | #ifdef CONFIG_X86_64 |
3991 | err_pml5: |
3992 | free_page((unsigned long)pml4_root); |
3993 | err_pml4: |
3994 | free_page((unsigned long)pae_root); |
3995 | return -ENOMEM; |
3996 | #endif |
3997 | } |
3998 | |
3999 | static bool is_unsync_root(hpa_t root) |
4000 | { |
4001 | struct kvm_mmu_page *sp; |
4002 | |
4003 | if (!VALID_PAGE(root) || kvm_mmu_is_dummy_root(shadow_page: root)) |
4004 | return false; |
4005 | |
4006 | /* |
4007 | * The read barrier orders the CPU's read of SPTE.W during the page table |
4008 | * walk before the reads of sp->unsync/sp->unsync_children here. |
4009 | * |
4010 | * Even if another CPU was marking the SP as unsync-ed simultaneously, |
4011 | * any guest page table changes are not guaranteed to be visible anyway |
4012 | * until this VCPU issues a TLB flush strictly after those changes are |
4013 | * made. We only need to ensure that the other CPU sets these flags |
4014 | * before any actual changes to the page tables are made. The comments |
4015 | * in mmu_try_to_unsync_pages() describe what could go wrong if this |
4016 | * requirement isn't satisfied. |
4017 | */ |
4018 | smp_rmb(); |
4019 | sp = root_to_sp(root); |
4020 | |
4021 | /* |
4022 | * PAE roots (somewhat arbitrarily) aren't backed by shadow pages, the |
4023 | * PDPTEs for a given PAE root need to be synchronized individually. |
4024 | */ |
4025 | if (WARN_ON_ONCE(!sp)) |
4026 | return false; |
4027 | |
4028 | if (sp->unsync || sp->unsync_children) |
4029 | return true; |
4030 | |
4031 | return false; |
4032 | } |
4033 | |
4034 | void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu) |
4035 | { |
4036 | int i; |
4037 | struct kvm_mmu_page *sp; |
4038 | |
4039 | if (vcpu->arch.mmu->root_role.direct) |
4040 | return; |
4041 | |
4042 | if (!VALID_PAGE(vcpu->arch.mmu->root.hpa)) |
4043 | return; |
4044 | |
4045 | vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); |
4046 | |
4047 | if (vcpu->arch.mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL) { |
4048 | hpa_t root = vcpu->arch.mmu->root.hpa; |
4049 | |
4050 | if (!is_unsync_root(root)) |
4051 | return; |
4052 | |
4053 | sp = root_to_sp(root); |
4054 | |
4055 | write_lock(&vcpu->kvm->mmu_lock); |
4056 | mmu_sync_children(vcpu, parent: sp, can_yield: true); |
4057 | write_unlock(&vcpu->kvm->mmu_lock); |
4058 | return; |
4059 | } |
4060 | |
4061 | write_lock(&vcpu->kvm->mmu_lock); |
4062 | |
4063 | for (i = 0; i < 4; ++i) { |
4064 | hpa_t root = vcpu->arch.mmu->pae_root[i]; |
4065 | |
4066 | if (IS_VALID_PAE_ROOT(root)) { |
4067 | sp = spte_to_child_sp(spte: root); |
4068 | mmu_sync_children(vcpu, parent: sp, can_yield: true); |
4069 | } |
4070 | } |
4071 | |
4072 | write_unlock(&vcpu->kvm->mmu_lock); |
4073 | } |
4074 | |
4075 | void kvm_mmu_sync_prev_roots(struct kvm_vcpu *vcpu) |
4076 | { |
4077 | unsigned long roots_to_free = 0; |
4078 | int i; |
4079 | |
4080 | for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) |
4081 | if (is_unsync_root(root: vcpu->arch.mmu->prev_roots[i].hpa)) |
4082 | roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); |
4083 | |
4084 | /* sync prev_roots by simply freeing them */ |
4085 | kvm_mmu_free_roots(vcpu->kvm, vcpu->arch.mmu, roots_to_free); |
4086 | } |
4087 | |
4088 | static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, |
4089 | gpa_t vaddr, u64 access, |
4090 | struct x86_exception *exception) |
4091 | { |
4092 | if (exception) |
4093 | exception->error_code = 0; |
4094 | return kvm_translate_gpa(vcpu, mmu, vaddr, access, exception); |
4095 | } |
4096 | |
4097 | static bool mmio_info_in_cache(struct kvm_vcpu *vcpu, u64 addr, bool direct) |
4098 | { |
4099 | /* |
4100 | * A nested guest cannot use the MMIO cache if it is using nested |
4101 | * page tables, because cr2 is a nGPA while the cache stores GPAs. |
4102 | */ |
4103 | if (mmu_is_nested(vcpu)) |
4104 | return false; |
4105 | |
4106 | if (direct) |
4107 | return vcpu_match_mmio_gpa(vcpu, addr); |
4108 | |
4109 | return vcpu_match_mmio_gva(vcpu, addr); |
4110 | } |
4111 | |
4112 | /* |
4113 | * Return the level of the lowest level SPTE added to sptes. |
4114 | * That SPTE may be non-present. |
4115 | * |
4116 | * Must be called between walk_shadow_page_lockless_{begin,end}. |
4117 | */ |
4118 | static int get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, int *root_level) |
4119 | { |
4120 | struct kvm_shadow_walk_iterator iterator; |
4121 | int leaf = -1; |
4122 | u64 spte; |
4123 | |
4124 | for (shadow_walk_init(iterator: &iterator, vcpu, addr), |
4125 | *root_level = iterator.level; |
4126 | shadow_walk_okay(iterator: &iterator); |
4127 | __shadow_walk_next(iterator: &iterator, spte)) { |
4128 | leaf = iterator.level; |
4129 | spte = mmu_spte_get_lockless(sptep: iterator.sptep); |
4130 | |
4131 | sptes[leaf] = spte; |
4132 | } |
4133 | |
4134 | return leaf; |
4135 | } |
4136 | |
4137 | /* return true if reserved bit(s) are detected on a valid, non-MMIO SPTE. */ |
4138 | static bool get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep) |
4139 | { |
4140 | u64 sptes[PT64_ROOT_MAX_LEVEL + 1]; |
4141 | struct rsvd_bits_validate *rsvd_check; |
4142 | int root, leaf, level; |
4143 | bool reserved = false; |
4144 | |
4145 | walk_shadow_page_lockless_begin(vcpu); |
4146 | |
4147 | if (is_tdp_mmu_active(vcpu)) |
4148 | leaf = kvm_tdp_mmu_get_walk(vcpu, addr, sptes, root_level: &root); |
4149 | else |
4150 | leaf = get_walk(vcpu, addr, sptes, root_level: &root); |
4151 | |
4152 | walk_shadow_page_lockless_end(vcpu); |
4153 | |
4154 | if (unlikely(leaf < 0)) { |
4155 | *sptep = 0ull; |
4156 | return reserved; |
4157 | } |
4158 | |
4159 | *sptep = sptes[leaf]; |
4160 | |
4161 | /* |
4162 | * Skip reserved bits checks on the terminal leaf if it's not a valid |
4163 | * SPTE. Note, this also (intentionally) skips MMIO SPTEs, which, by |
4164 | * design, always have reserved bits set. The purpose of the checks is |
4165 | * to detect reserved bits on non-MMIO SPTEs. i.e. buggy SPTEs. |
4166 | */ |
4167 | if (!is_shadow_present_pte(pte: sptes[leaf])) |
4168 | leaf++; |
4169 | |
4170 | rsvd_check = &vcpu->arch.mmu->shadow_zero_check; |
4171 | |
4172 | for (level = root; level >= leaf; level--) |
4173 | reserved |= is_rsvd_spte(rsvd_check, spte: sptes[level], level); |
4174 | |
4175 | if (reserved) { |
4176 | pr_err("%s: reserved bits set on MMU-present spte, addr 0x%llx, hierarchy:\n" , |
4177 | __func__, addr); |
4178 | for (level = root; level >= leaf; level--) |
4179 | pr_err("------ spte = 0x%llx level = %d, rsvd bits = 0x%llx" , |
4180 | sptes[level], level, |
4181 | get_rsvd_bits(rsvd_check, sptes[level], level)); |
4182 | } |
4183 | |
4184 | return reserved; |
4185 | } |
4186 | |
4187 | static int handle_mmio_page_fault(struct kvm_vcpu *vcpu, u64 addr, bool direct) |
4188 | { |
4189 | u64 spte; |
4190 | bool reserved; |
4191 | |
4192 | if (mmio_info_in_cache(vcpu, addr, direct)) |
4193 | return RET_PF_EMULATE; |
4194 | |
4195 | reserved = get_mmio_spte(vcpu, addr, sptep: &spte); |
4196 | if (WARN_ON_ONCE(reserved)) |
4197 | return -EINVAL; |
4198 | |
4199 | if (is_mmio_spte(spte)) { |
4200 | gfn_t gfn = get_mmio_spte_gfn(spte); |
4201 | unsigned int access = get_mmio_spte_access(spte); |
4202 | |
4203 | if (!check_mmio_spte(vcpu, spte)) |
4204 | return RET_PF_INVALID; |
4205 | |
4206 | if (direct) |
4207 | addr = 0; |
4208 | |
4209 | trace_handle_mmio_page_fault(addr, gfn, access); |
4210 | vcpu_cache_mmio_info(vcpu, addr, gfn, access); |
4211 | return RET_PF_EMULATE; |
4212 | } |
4213 | |
4214 | /* |
4215 | * If the page table is zapped by other cpus, let CPU fault again on |
4216 | * the address. |
4217 | */ |
4218 | return RET_PF_RETRY; |
4219 | } |
4220 | |
4221 | static bool page_fault_handle_page_track(struct kvm_vcpu *vcpu, |
4222 | struct kvm_page_fault *fault) |
4223 | { |
4224 | if (unlikely(fault->rsvd)) |
4225 | return false; |
4226 | |
4227 | if (!fault->present || !fault->write) |
4228 | return false; |
4229 | |
4230 | /* |
4231 | * guest is writing the page which is write tracked which can |
4232 | * not be fixed by page fault handler. |
4233 | */ |
4234 | if (kvm_gfn_is_write_tracked(kvm: vcpu->kvm, slot: fault->slot, gfn: fault->gfn)) |
4235 | return true; |
4236 | |
4237 | return false; |
4238 | } |
4239 | |
4240 | static void shadow_page_table_clear_flood(struct kvm_vcpu *vcpu, gva_t addr) |
4241 | { |
4242 | struct kvm_shadow_walk_iterator iterator; |
4243 | u64 spte; |
4244 | |
4245 | walk_shadow_page_lockless_begin(vcpu); |
4246 | for_each_shadow_entry_lockless(vcpu, addr, iterator, spte) |
4247 | clear_sp_write_flooding_count(spte: iterator.sptep); |
4248 | walk_shadow_page_lockless_end(vcpu); |
4249 | } |
4250 | |
4251 | static u32 alloc_apf_token(struct kvm_vcpu *vcpu) |
4252 | { |
4253 | /* make sure the token value is not 0 */ |
4254 | u32 id = vcpu->arch.apf.id; |
4255 | |
4256 | if (id << 12 == 0) |
4257 | vcpu->arch.apf.id = 1; |
4258 | |
4259 | return (vcpu->arch.apf.id++ << 12) | vcpu->vcpu_id; |
4260 | } |
4261 | |
4262 | static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, |
4263 | gfn_t gfn) |
4264 | { |
4265 | struct kvm_arch_async_pf arch; |
4266 | |
4267 | arch.token = alloc_apf_token(vcpu); |
4268 | arch.gfn = gfn; |
4269 | arch.direct_map = vcpu->arch.mmu->root_role.direct; |
4270 | arch.cr3 = kvm_mmu_get_guest_pgd(vcpu, mmu: vcpu->arch.mmu); |
4271 | |
4272 | return kvm_setup_async_pf(vcpu, cr2_or_gpa, |
4273 | hva: kvm_vcpu_gfn_to_hva(vcpu, gfn), arch: &arch); |
4274 | } |
4275 | |
4276 | void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) |
4277 | { |
4278 | int r; |
4279 | |
4280 | if ((vcpu->arch.mmu->root_role.direct != work->arch.direct_map) || |
4281 | work->wakeup_all) |
4282 | return; |
4283 | |
4284 | r = kvm_mmu_reload(vcpu); |
4285 | if (unlikely(r)) |
4286 | return; |
4287 | |
4288 | if (!vcpu->arch.mmu->root_role.direct && |
4289 | work->arch.cr3 != kvm_mmu_get_guest_pgd(vcpu, mmu: vcpu->arch.mmu)) |
4290 | return; |
4291 | |
4292 | kvm_mmu_do_page_fault(vcpu, cr2_or_gpa: work->cr2_or_gpa, err: 0, prefetch: true, NULL); |
4293 | } |
4294 | |
4295 | static inline u8 kvm_max_level_for_order(int order) |
4296 | { |
4297 | BUILD_BUG_ON(KVM_MAX_HUGEPAGE_LEVEL > PG_LEVEL_1G); |
4298 | |
4299 | KVM_MMU_WARN_ON(order != KVM_HPAGE_GFN_SHIFT(PG_LEVEL_1G) && |
4300 | order != KVM_HPAGE_GFN_SHIFT(PG_LEVEL_2M) && |
4301 | order != KVM_HPAGE_GFN_SHIFT(PG_LEVEL_4K)); |
4302 | |
4303 | if (order >= KVM_HPAGE_GFN_SHIFT(PG_LEVEL_1G)) |
4304 | return PG_LEVEL_1G; |
4305 | |
4306 | if (order >= KVM_HPAGE_GFN_SHIFT(PG_LEVEL_2M)) |
4307 | return PG_LEVEL_2M; |
4308 | |
4309 | return PG_LEVEL_4K; |
4310 | } |
4311 | |
4312 | static void kvm_mmu_prepare_memory_fault_exit(struct kvm_vcpu *vcpu, |
4313 | struct kvm_page_fault *fault) |
4314 | { |
4315 | kvm_prepare_memory_fault_exit(vcpu, gpa: fault->gfn << PAGE_SHIFT, |
4316 | PAGE_SIZE, is_write: fault->write, is_exec: fault->exec, |
4317 | is_private: fault->is_private); |
4318 | } |
4319 | |
4320 | static int kvm_faultin_pfn_private(struct kvm_vcpu *vcpu, |
4321 | struct kvm_page_fault *fault) |
4322 | { |
4323 | int max_order, r; |
4324 | |
4325 | if (!kvm_slot_can_be_private(slot: fault->slot)) { |
4326 | kvm_mmu_prepare_memory_fault_exit(vcpu, fault); |
4327 | return -EFAULT; |
4328 | } |
4329 | |
4330 | r = kvm_gmem_get_pfn(kvm: vcpu->kvm, slot: fault->slot, gfn: fault->gfn, pfn: &fault->pfn, |
4331 | max_order: &max_order); |
4332 | if (r) { |
4333 | kvm_mmu_prepare_memory_fault_exit(vcpu, fault); |
4334 | return r; |
4335 | } |
4336 | |
4337 | fault->max_level = min(kvm_max_level_for_order(max_order), |
4338 | fault->max_level); |
4339 | fault->map_writable = !(fault->slot->flags & KVM_MEM_READONLY); |
4340 | |
4341 | return RET_PF_CONTINUE; |
4342 | } |
4343 | |
4344 | static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) |
4345 | { |
4346 | struct kvm_memory_slot *slot = fault->slot; |
4347 | bool async; |
4348 | |
4349 | /* |
4350 | * Retry the page fault if the gfn hit a memslot that is being deleted |
4351 | * or moved. This ensures any existing SPTEs for the old memslot will |
4352 | * be zapped before KVM inserts a new MMIO SPTE for the gfn. |
4353 | */ |
4354 | if (slot && (slot->flags & KVM_MEMSLOT_INVALID)) |
4355 | return RET_PF_RETRY; |
4356 | |
4357 | if (!kvm_is_visible_memslot(memslot: slot)) { |
4358 | /* Don't expose private memslots to L2. */ |
4359 | if (is_guest_mode(vcpu)) { |
4360 | fault->slot = NULL; |
4361 | fault->pfn = KVM_PFN_NOSLOT; |
4362 | fault->map_writable = false; |
4363 | return RET_PF_CONTINUE; |
4364 | } |
4365 | /* |
4366 | * If the APIC access page exists but is disabled, go directly |
4367 | * to emulation without caching the MMIO access or creating a |
4368 | * MMIO SPTE. That way the cache doesn't need to be purged |
4369 | * when the AVIC is re-enabled. |
4370 | */ |
4371 | if (slot && slot->id == APIC_ACCESS_PAGE_PRIVATE_MEMSLOT && |
4372 | !kvm_apicv_activated(kvm: vcpu->kvm)) |
4373 | return RET_PF_EMULATE; |
4374 | } |
4375 | |
4376 | if (fault->is_private != kvm_mem_is_private(kvm: vcpu->kvm, gfn: fault->gfn)) { |
4377 | kvm_mmu_prepare_memory_fault_exit(vcpu, fault); |
4378 | return -EFAULT; |
4379 | } |
4380 | |
4381 | if (fault->is_private) |
4382 | return kvm_faultin_pfn_private(vcpu, fault); |
4383 | |
4384 | async = false; |
4385 | fault->pfn = __gfn_to_pfn_memslot(slot, gfn: fault->gfn, atomic: false, interruptible: false, async: &async, |
4386 | write_fault: fault->write, writable: &fault->map_writable, |
4387 | hva: &fault->hva); |
4388 | if (!async) |
4389 | return RET_PF_CONTINUE; /* *pfn has correct page already */ |
4390 | |
4391 | if (!fault->prefetch && kvm_can_do_async_pf(vcpu)) { |
4392 | trace_kvm_try_async_get_page(gva: fault->addr, gfn: fault->gfn); |
4393 | if (kvm_find_async_pf_gfn(vcpu, gfn: fault->gfn)) { |
4394 | trace_kvm_async_pf_repeated_fault(gva: fault->addr, gfn: fault->gfn); |
4395 | kvm_make_request(KVM_REQ_APF_HALT, vcpu); |
4396 | return RET_PF_RETRY; |
4397 | } else if (kvm_arch_setup_async_pf(vcpu, cr2_or_gpa: fault->addr, gfn: fault->gfn)) { |
4398 | return RET_PF_RETRY; |
4399 | } |
4400 | } |
4401 | |
4402 | /* |
4403 | * Allow gup to bail on pending non-fatal signals when it's also allowed |
4404 | * to wait for IO. Note, gup always bails if it is unable to quickly |
4405 | * get a page and a fatal signal, i.e. SIGKILL, is pending. |
4406 | */ |
4407 | fault->pfn = __gfn_to_pfn_memslot(slot, gfn: fault->gfn, atomic: false, interruptible: true, NULL, |
4408 | write_fault: fault->write, writable: &fault->map_writable, |
4409 | hva: &fault->hva); |
4410 | return RET_PF_CONTINUE; |
4411 | } |
4412 | |
4413 | static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, |
4414 | unsigned int access) |
4415 | { |
4416 | int ret; |
4417 | |
4418 | fault->mmu_seq = vcpu->kvm->mmu_invalidate_seq; |
4419 | smp_rmb(); |
4420 | |
4421 | /* |
4422 | * Check for a relevant mmu_notifier invalidation event before getting |
4423 | * the pfn from the primary MMU, and before acquiring mmu_lock. |
4424 | * |
4425 | * For mmu_lock, if there is an in-progress invalidation and the kernel |
4426 | * allows preemption, the invalidation task may drop mmu_lock and yield |
4427 | * in response to mmu_lock being contended, which is *very* counter- |
4428 | * productive as this vCPU can't actually make forward progress until |
4429 | * the invalidation completes. |
4430 | * |
4431 | * Retrying now can also avoid unnessary lock contention in the primary |
4432 | * MMU, as the primary MMU doesn't necessarily hold a single lock for |
4433 | * the duration of the invalidation, i.e. faulting in a conflicting pfn |
4434 | * can cause the invalidation to take longer by holding locks that are |
4435 | * needed to complete the invalidation. |
4436 | * |
4437 | * Do the pre-check even for non-preemtible kernels, i.e. even if KVM |
4438 | * will never yield mmu_lock in response to contention, as this vCPU is |
4439 | * *guaranteed* to need to retry, i.e. waiting until mmu_lock is held |
4440 | * to detect retry guarantees the worst case latency for the vCPU. |
4441 | */ |
4442 | if (fault->slot && |
4443 | mmu_invalidate_retry_gfn_unsafe(kvm: vcpu->kvm, mmu_seq: fault->mmu_seq, gfn: fault->gfn)) |
4444 | return RET_PF_RETRY; |
4445 | |
4446 | ret = __kvm_faultin_pfn(vcpu, fault); |
4447 | if (ret != RET_PF_CONTINUE) |
4448 | return ret; |
4449 | |
4450 | if (unlikely(is_error_pfn(fault->pfn))) |
4451 | return kvm_handle_error_pfn(vcpu, fault); |
4452 | |
4453 | if (unlikely(!fault->slot)) |
4454 | return kvm_handle_noslot_fault(vcpu, fault, access); |
4455 | |
4456 | /* |
4457 | * Check again for a relevant mmu_notifier invalidation event purely to |
4458 | * avoid contending mmu_lock. Most invalidations will be detected by |
4459 | * the previous check, but checking is extremely cheap relative to the |
4460 | * overall cost of failing to detect the invalidation until after |
4461 | * mmu_lock is acquired. |
4462 | */ |
4463 | if (mmu_invalidate_retry_gfn_unsafe(kvm: vcpu->kvm, mmu_seq: fault->mmu_seq, gfn: fault->gfn)) { |
4464 | kvm_release_pfn_clean(pfn: fault->pfn); |
4465 | return RET_PF_RETRY; |
4466 | } |
4467 | |
4468 | return RET_PF_CONTINUE; |
4469 | } |
4470 | |
4471 | /* |
4472 | * Returns true if the page fault is stale and needs to be retried, i.e. if the |
4473 | * root was invalidated by a memslot update or a relevant mmu_notifier fired. |
4474 | */ |
4475 | static bool is_page_fault_stale(struct kvm_vcpu *vcpu, |
4476 | struct kvm_page_fault *fault) |
4477 | { |
4478 | struct kvm_mmu_page *sp = root_to_sp(root: vcpu->arch.mmu->root.hpa); |
4479 | |
4480 | /* Special roots, e.g. pae_root, are not backed by shadow pages. */ |
4481 | if (sp && is_obsolete_sp(kvm: vcpu->kvm, sp)) |
4482 | return true; |
4483 | |
4484 | /* |
4485 | * Roots without an associated shadow page are considered invalid if |
4486 | * there is a pending request to free obsolete roots. The request is |
4487 | * only a hint that the current root _may_ be obsolete and needs to be |
4488 | * reloaded, e.g. if the guest frees a PGD that KVM is tracking as a |
4489 | * previous root, then __kvm_mmu_prepare_zap_page() signals all vCPUs |
4490 | * to reload even if no vCPU is actively using the root. |
4491 | */ |
4492 | if (!sp && kvm_test_request(KVM_REQ_MMU_FREE_OBSOLETE_ROOTS, vcpu)) |
4493 | return true; |
4494 | |
4495 | /* |
4496 | * Check for a relevant mmu_notifier invalidation event one last time |
4497 | * now that mmu_lock is held, as the "unsafe" checks performed without |
4498 | * holding mmu_lock can get false negatives. |
4499 | */ |
4500 | return fault->slot && |
4501 | mmu_invalidate_retry_gfn(kvm: vcpu->kvm, mmu_seq: fault->mmu_seq, gfn: fault->gfn); |
4502 | } |
4503 | |
4504 | static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) |
4505 | { |
4506 | int r; |
4507 | |
4508 | /* Dummy roots are used only for shadowing bad guest roots. */ |
4509 | if (WARN_ON_ONCE(kvm_mmu_is_dummy_root(vcpu->arch.mmu->root.hpa))) |
4510 | return RET_PF_RETRY; |
4511 | |
4512 | if (page_fault_handle_page_track(vcpu, fault)) |
4513 | return RET_PF_EMULATE; |
4514 | |
4515 | r = fast_page_fault(vcpu, fault); |
4516 | if (r != RET_PF_INVALID) |
4517 | return r; |
4518 | |
4519 | r = mmu_topup_memory_caches(vcpu, maybe_indirect: false); |
4520 | if (r) |
4521 | return r; |
4522 | |
4523 | r = kvm_faultin_pfn(vcpu, fault, ACC_ALL); |
4524 | if (r != RET_PF_CONTINUE) |
4525 | return r; |
4526 | |
4527 | r = RET_PF_RETRY; |
4528 | write_lock(&vcpu->kvm->mmu_lock); |
4529 | |
4530 | if (is_page_fault_stale(vcpu, fault)) |
4531 | goto out_unlock; |
4532 | |
4533 | r = make_mmu_pages_available(vcpu); |
4534 | if (r) |
4535 | goto out_unlock; |
4536 | |
4537 | r = direct_map(vcpu, fault); |
4538 | |
4539 | out_unlock: |
4540 | write_unlock(&vcpu->kvm->mmu_lock); |
4541 | kvm_release_pfn_clean(pfn: fault->pfn); |
4542 | return r; |
4543 | } |
4544 | |
4545 | static int nonpaging_page_fault(struct kvm_vcpu *vcpu, |
4546 | struct kvm_page_fault *fault) |
4547 | { |
4548 | /* This path builds a PAE pagetable, we can map 2mb pages at maximum. */ |
4549 | fault->max_level = PG_LEVEL_2M; |
4550 | return direct_page_fault(vcpu, fault); |
4551 | } |
4552 | |
4553 | int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code, |
4554 | u64 fault_address, char *insn, int insn_len) |
4555 | { |
4556 | int r = 1; |
4557 | u32 flags = vcpu->arch.apf.host_apf_flags; |
4558 | |
4559 | #ifndef CONFIG_X86_64 |
4560 | /* A 64-bit CR2 should be impossible on 32-bit KVM. */ |
4561 | if (WARN_ON_ONCE(fault_address >> 32)) |
4562 | return -EFAULT; |
4563 | #endif |
4564 | |
4565 | vcpu->arch.l1tf_flush_l1d = true; |
4566 | if (!flags) { |
4567 | trace_kvm_page_fault(vcpu, fault_address, error_code); |
4568 | |
4569 | if (kvm_event_needs_reinjection(vcpu)) |
4570 | kvm_mmu_unprotect_page_virt(vcpu, gva: fault_address); |
4571 | r = kvm_mmu_page_fault(vcpu, cr2_or_gpa: fault_address, error_code, insn, |
4572 | insn_len); |
4573 | } else if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) { |
4574 | vcpu->arch.apf.host_apf_flags = 0; |
4575 | local_irq_disable(); |
4576 | kvm_async_pf_task_wait_schedule(token: fault_address); |
4577 | local_irq_enable(); |
4578 | } else { |
4579 | WARN_ONCE(1, "Unexpected host async PF flags: %x\n" , flags); |
4580 | } |
4581 | |
4582 | return r; |
4583 | } |
4584 | EXPORT_SYMBOL_GPL(kvm_handle_page_fault); |
4585 | |
4586 | #ifdef CONFIG_X86_64 |
4587 | static int kvm_tdp_mmu_page_fault(struct kvm_vcpu *vcpu, |
4588 | struct kvm_page_fault *fault) |
4589 | { |
4590 | int r; |
4591 | |
4592 | if (page_fault_handle_page_track(vcpu, fault)) |
4593 | return RET_PF_EMULATE; |
4594 | |
4595 | r = fast_page_fault(vcpu, fault); |
4596 | if (r != RET_PF_INVALID) |
4597 | return r; |
4598 | |
4599 | r = mmu_topup_memory_caches(vcpu, maybe_indirect: false); |
4600 | if (r) |
4601 | return r; |
4602 | |
4603 | r = kvm_faultin_pfn(vcpu, fault, ACC_ALL); |
4604 | if (r != RET_PF_CONTINUE) |
4605 | return r; |
4606 | |
4607 | r = RET_PF_RETRY; |
4608 | read_lock(&vcpu->kvm->mmu_lock); |
4609 | |
4610 | if (is_page_fault_stale(vcpu, fault)) |
4611 | goto out_unlock; |
4612 | |
4613 | r = kvm_tdp_mmu_map(vcpu, fault); |
4614 | |
4615 | out_unlock: |
4616 | read_unlock(&vcpu->kvm->mmu_lock); |
4617 | kvm_release_pfn_clean(pfn: fault->pfn); |
4618 | return r; |
4619 | } |
4620 | #endif |
4621 | |
4622 | bool __kvm_mmu_honors_guest_mtrrs(bool vm_has_noncoherent_dma) |
4623 | { |
4624 | /* |
4625 | * If host MTRRs are ignored (shadow_memtype_mask is non-zero), and the |
4626 | * VM has non-coherent DMA (DMA doesn't snoop CPU caches), KVM's ABI is |
4627 | * to honor the memtype from the guest's MTRRs so that guest accesses |
4628 | * to memory that is DMA'd aren't cached against the guest's wishes. |
4629 | * |
4630 | * Note, KVM may still ultimately ignore guest MTRRs for certain PFNs, |
4631 | * e.g. KVM will force UC memtype for host MMIO. |
4632 | */ |
4633 | return vm_has_noncoherent_dma && shadow_memtype_mask; |
4634 | } |
4635 | |
4636 | int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) |
4637 | { |
4638 | /* |
4639 | * If the guest's MTRRs may be used to compute the "real" memtype, |
4640 | * restrict the mapping level to ensure KVM uses a consistent memtype |
4641 | * across the entire mapping. |
4642 | */ |
4643 | if (kvm_mmu_honors_guest_mtrrs(vcpu->kvm)) { |
4644 | for ( ; fault->max_level > PG_LEVEL_4K; --fault->max_level) { |
4645 | int page_num = KVM_PAGES_PER_HPAGE(fault->max_level); |
4646 | gfn_t base = gfn_round_for_level(gfn: fault->gfn, |
4647 | level: fault->max_level); |
4648 | |
4649 | if (kvm_mtrr_check_gfn_range_consistency(vcpu, base, page_num)) |
4650 | break; |
4651 | } |
4652 | } |
4653 | |
4654 | #ifdef CONFIG_X86_64 |
4655 | if (tdp_mmu_enabled) |
4656 | return kvm_tdp_mmu_page_fault(vcpu, fault); |
4657 | #endif |
4658 | |
4659 | return direct_page_fault(vcpu, fault); |
4660 | } |
4661 | |
4662 | static void nonpaging_init_context(struct kvm_mmu *context) |
4663 | { |
4664 | context->page_fault = nonpaging_page_fault; |
4665 | context->gva_to_gpa = nonpaging_gva_to_gpa; |
4666 | context->sync_spte = NULL; |
4667 | } |
4668 | |
4669 | static inline bool is_root_usable(struct kvm_mmu_root_info *root, gpa_t pgd, |
4670 | union kvm_mmu_page_role role) |
4671 | { |
4672 | struct kvm_mmu_page *sp; |
4673 | |
4674 | if (!VALID_PAGE(root->hpa)) |
4675 | return false; |
4676 | |
4677 | if (!role.direct && pgd != root->pgd) |
4678 | return false; |
4679 | |
4680 | sp = root_to_sp(root: root->hpa); |
4681 | if (WARN_ON_ONCE(!sp)) |
4682 | return false; |
4683 | |
4684 | return role.word == sp->role.word; |
4685 | } |
4686 | |
4687 | /* |
4688 | * Find out if a previously cached root matching the new pgd/role is available, |
4689 | * and insert the current root as the MRU in the cache. |
4690 | * If a matching root is found, it is assigned to kvm_mmu->root and |
4691 | * true is returned. |
4692 | * If no match is found, kvm_mmu->root is left invalid, the LRU root is |
4693 | * evicted to make room for the current root, and false is returned. |
4694 | */ |
4695 | static bool cached_root_find_and_keep_current(struct kvm *kvm, struct kvm_mmu *mmu, |
4696 | gpa_t new_pgd, |
4697 | union kvm_mmu_page_role new_role) |
4698 | { |
4699 | uint i; |
4700 | |
4701 | if (is_root_usable(root: &mmu->root, pgd: new_pgd, role: new_role)) |
4702 | return true; |
4703 | |
4704 | for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { |
4705 | /* |
4706 | * The swaps end up rotating the cache like this: |
4707 | * C 0 1 2 3 (on entry to the function) |
4708 | * 0 C 1 2 3 |
4709 | * 1 C 0 2 3 |
4710 | * 2 C 0 1 3 |
4711 | * 3 C 0 1 2 (on exit from the loop) |
4712 | */ |
4713 | swap(mmu->root, mmu->prev_roots[i]); |
4714 | if (is_root_usable(root: &mmu->root, pgd: new_pgd, role: new_role)) |
4715 | return true; |
4716 | } |
4717 | |
4718 | kvm_mmu_free_roots(kvm, mmu, KVM_MMU_ROOT_CURRENT); |
4719 | return false; |
4720 | } |
4721 | |
4722 | /* |
4723 | * Find out if a previously cached root matching the new pgd/role is available. |
4724 | * On entry, mmu->root is invalid. |
4725 | * If a matching root is found, it is assigned to kvm_mmu->root, the LRU entry |
4726 | * of the cache becomes invalid, and true is returned. |
4727 | * If no match is found, kvm_mmu->root is left invalid and false is returned. |
4728 | */ |
4729 | static bool cached_root_find_without_current(struct kvm *kvm, struct kvm_mmu *mmu, |
4730 | gpa_t new_pgd, |
4731 | union kvm_mmu_page_role new_role) |
4732 | { |
4733 | uint i; |
4734 | |
4735 | for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) |
4736 | if (is_root_usable(root: &mmu->prev_roots[i], pgd: new_pgd, role: new_role)) |
4737 | goto hit; |
4738 | |
4739 | return false; |
4740 | |
4741 | hit: |
4742 | swap(mmu->root, mmu->prev_roots[i]); |
4743 | /* Bubble up the remaining roots. */ |
4744 | for (; i < KVM_MMU_NUM_PREV_ROOTS - 1; i++) |
4745 | mmu->prev_roots[i] = mmu->prev_roots[i + 1]; |
4746 | mmu->prev_roots[i].hpa = INVALID_PAGE; |
4747 | return true; |
4748 | } |
4749 | |
4750 | static bool fast_pgd_switch(struct kvm *kvm, struct kvm_mmu *mmu, |
4751 | gpa_t new_pgd, union kvm_mmu_page_role new_role) |
4752 | { |
4753 | /* |
4754 | * Limit reuse to 64-bit hosts+VMs without "special" roots in order to |
4755 | * avoid having to deal with PDPTEs and other complexities. |
4756 | */ |
4757 | if (VALID_PAGE(mmu->root.hpa) && !root_to_sp(root: mmu->root.hpa)) |
4758 | kvm_mmu_free_roots(kvm, mmu, KVM_MMU_ROOT_CURRENT); |
4759 | |
4760 | if (VALID_PAGE(mmu->root.hpa)) |
4761 | return cached_root_find_and_keep_current(kvm, mmu, new_pgd, new_role); |
4762 | else |
4763 | return cached_root_find_without_current(kvm, mmu, new_pgd, new_role); |
4764 | } |
4765 | |
4766 | void kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd) |
4767 | { |
4768 | struct kvm_mmu *mmu = vcpu->arch.mmu; |
4769 | union kvm_mmu_page_role new_role = mmu->root_role; |
4770 | |
4771 | /* |
4772 | * Return immediately if no usable root was found, kvm_mmu_reload() |
4773 | * will establish a valid root prior to the next VM-Enter. |
4774 | */ |
4775 | if (!fast_pgd_switch(kvm: vcpu->kvm, mmu, new_pgd, new_role)) |
4776 | return; |
4777 | |
4778 | /* |
4779 | * It's possible that the cached previous root page is obsolete because |
4780 | * of a change in the MMU generation number. However, changing the |
4781 | * generation number is accompanied by KVM_REQ_MMU_FREE_OBSOLETE_ROOTS, |
4782 | * which will free the root set here and allocate a new one. |
4783 | */ |
4784 | kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu); |
4785 | |
4786 | if (force_flush_and_sync_on_reuse) { |
4787 | kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); |
4788 | kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); |
4789 | } |
4790 | |
4791 | /* |
4792 | * The last MMIO access's GVA and GPA are cached in the VCPU. When |
4793 | * switching to a new CR3, that GVA->GPA mapping may no longer be |
4794 | * valid. So clear any cached MMIO info even when we don't need to sync |
4795 | * the shadow page tables. |
4796 | */ |
4797 | vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); |
4798 | |
4799 | /* |
4800 | * If this is a direct root page, it doesn't have a write flooding |
4801 | * count. Otherwise, clear the write flooding count. |
4802 | */ |
4803 | if (!new_role.direct) { |
4804 | struct kvm_mmu_page *sp = root_to_sp(root: vcpu->arch.mmu->root.hpa); |
4805 | |
4806 | if (!WARN_ON_ONCE(!sp)) |
4807 | __clear_sp_write_flooding_count(sp); |
4808 | } |
4809 | } |
4810 | EXPORT_SYMBOL_GPL(kvm_mmu_new_pgd); |
4811 | |
4812 | static bool sync_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn, |
4813 | unsigned int access) |
4814 | { |
4815 | if (unlikely(is_mmio_spte(*sptep))) { |
4816 | if (gfn != get_mmio_spte_gfn(spte: *sptep)) { |
4817 | mmu_spte_clear_no_track(sptep); |
4818 | return true; |
4819 | } |
4820 | |
4821 | mark_mmio_spte(vcpu, sptep, gfn, access); |
4822 | return true; |
4823 | } |
4824 | |
4825 | return false; |
4826 | } |
4827 | |
4828 | #define PTTYPE_EPT 18 /* arbitrary */ |
4829 | #define PTTYPE PTTYPE_EPT |
4830 | #include "paging_tmpl.h" |
4831 | #undef PTTYPE |
4832 | |
4833 | #define PTTYPE 64 |
4834 | #include "paging_tmpl.h" |
4835 | #undef PTTYPE |
4836 | |
4837 | #define PTTYPE 32 |
4838 | #include "paging_tmpl.h" |
4839 | #undef PTTYPE |
4840 | |
4841 | static void __reset_rsvds_bits_mask(struct rsvd_bits_validate *rsvd_check, |
4842 | u64 pa_bits_rsvd, int level, bool nx, |
4843 | bool gbpages, bool pse, bool amd) |
4844 | { |
4845 | u64 gbpages_bit_rsvd = 0; |
4846 | u64 nonleaf_bit8_rsvd = 0; |
4847 | u64 high_bits_rsvd; |
4848 | |
4849 | rsvd_check->bad_mt_xwr = 0; |
4850 | |
4851 | if (!gbpages) |
4852 | gbpages_bit_rsvd = rsvd_bits(7, 7); |
4853 | |
4854 | if (level == PT32E_ROOT_LEVEL) |
4855 | high_bits_rsvd = pa_bits_rsvd & rsvd_bits(0, 62); |
4856 | else |
4857 | high_bits_rsvd = pa_bits_rsvd & rsvd_bits(0, 51); |
4858 | |
4859 | /* Note, NX doesn't exist in PDPTEs, this is handled below. */ |
4860 | if (!nx) |
4861 | high_bits_rsvd |= rsvd_bits(63, 63); |
4862 | |
4863 | /* |
4864 | * Non-leaf PML4Es and PDPEs reserve bit 8 (which would be the G bit for |
4865 | * leaf entries) on AMD CPUs only. |
4866 | */ |
4867 | if (amd) |
4868 | nonleaf_bit8_rsvd = rsvd_bits(8, 8); |
4869 | |
4870 | switch (level) { |
4871 | case PT32_ROOT_LEVEL: |
4872 | /* no rsvd bits for 2 level 4K page table entries */ |
4873 | rsvd_check->rsvd_bits_mask[0][1] = 0; |
4874 | rsvd_check->rsvd_bits_mask[0][0] = 0; |
4875 | rsvd_check->rsvd_bits_mask[1][0] = |
4876 | rsvd_check->rsvd_bits_mask[0][0]; |
4877 | |
4878 | if (!pse) { |
4879 | rsvd_check->rsvd_bits_mask[1][1] = 0; |
4880 | break; |
4881 | } |
4882 | |
4883 | if (is_cpuid_PSE36()) |
4884 | /* 36bits PSE 4MB page */ |
4885 | rsvd_check->rsvd_bits_mask[1][1] = rsvd_bits(17, 21); |
4886 | else |
4887 | /* 32 bits PSE 4MB page */ |
4888 | rsvd_check->rsvd_bits_mask[1][1] = rsvd_bits(13, 21); |
4889 | break; |
4890 | case PT32E_ROOT_LEVEL: |
4891 | rsvd_check->rsvd_bits_mask[0][2] = rsvd_bits(63, 63) | |
4892 | high_bits_rsvd | |
4893 | rsvd_bits(5, 8) | |
4894 | rsvd_bits(1, 2); /* PDPTE */ |
4895 | rsvd_check->rsvd_bits_mask[0][1] = high_bits_rsvd; /* PDE */ |
4896 | rsvd_check->rsvd_bits_mask[0][0] = high_bits_rsvd; /* PTE */ |
4897 | rsvd_check->rsvd_bits_mask[1][1] = high_bits_rsvd | |
4898 | rsvd_bits(13, 20); /* large page */ |
4899 | rsvd_check->rsvd_bits_mask[1][0] = |
4900 | rsvd_check->rsvd_bits_mask[0][0]; |
4901 | break; |
4902 | case PT64_ROOT_5LEVEL: |
4903 | rsvd_check->rsvd_bits_mask[0][4] = high_bits_rsvd | |
4904 | nonleaf_bit8_rsvd | |
4905 | rsvd_bits(7, 7); |
4906 | rsvd_check->rsvd_bits_mask[1][4] = |
4907 | rsvd_check->rsvd_bits_mask[0][4]; |
4908 | fallthrough; |
4909 | case PT64_ROOT_4LEVEL: |
4910 | rsvd_check->rsvd_bits_mask[0][3] = high_bits_rsvd | |
4911 | nonleaf_bit8_rsvd | |
4912 | rsvd_bits(7, 7); |
4913 | rsvd_check->rsvd_bits_mask[0][2] = high_bits_rsvd | |
4914 | gbpages_bit_rsvd; |
4915 | rsvd_check->rsvd_bits_mask[0][1] = high_bits_rsvd; |
4916 | rsvd_check->rsvd_bits_mask[0][0] = high_bits_rsvd; |
4917 | rsvd_check->rsvd_bits_mask[1][3] = |
4918 | rsvd_check->rsvd_bits_mask[0][3]; |
4919 | rsvd_check->rsvd_bits_mask[1][2] = high_bits_rsvd | |
4920 | gbpages_bit_rsvd | |
4921 | rsvd_bits(13, 29); |
4922 | rsvd_check->rsvd_bits_mask[1][1] = high_bits_rsvd | |
4923 | rsvd_bits(13, 20); /* large page */ |
4924 | rsvd_check->rsvd_bits_mask[1][0] = |
4925 | rsvd_check->rsvd_bits_mask[0][0]; |
4926 | break; |
4927 | } |
4928 | } |
4929 | |
4930 | static void reset_guest_rsvds_bits_mask(struct kvm_vcpu *vcpu, |
4931 | struct kvm_mmu *context) |
4932 | { |
4933 | __reset_rsvds_bits_mask(rsvd_check: &context->guest_rsvd_check, |
4934 | pa_bits_rsvd: vcpu->arch.reserved_gpa_bits, |
4935 | level: context->cpu_role.base.level, nx: is_efer_nx(mmu: context), |
4936 | gbpages: guest_can_use(vcpu, X86_FEATURE_GBPAGES), |
4937 | pse: is_cr4_pse(mmu: context), |
4938 | amd: guest_cpuid_is_amd_compatible(vcpu)); |
4939 | } |
4940 | |
4941 | static void __reset_rsvds_bits_mask_ept(struct rsvd_bits_validate *rsvd_check, |
4942 | u64 pa_bits_rsvd, bool execonly, |
4943 | int huge_page_level) |
4944 | { |
4945 | u64 high_bits_rsvd = pa_bits_rsvd & rsvd_bits(0, 51); |
4946 | u64 large_1g_rsvd = 0, large_2m_rsvd = 0; |
4947 | u64 bad_mt_xwr; |
4948 | |
4949 | if (huge_page_level < PG_LEVEL_1G) |
4950 | large_1g_rsvd = rsvd_bits(7, 7); |
4951 | if (huge_page_level < PG_LEVEL_2M) |
4952 | large_2m_rsvd = rsvd_bits(7, 7); |
4953 | |
4954 | rsvd_check->rsvd_bits_mask[0][4] = high_bits_rsvd | rsvd_bits(3, 7); |
4955 | rsvd_check->rsvd_bits_mask[0][3] = high_bits_rsvd | rsvd_bits(3, 7); |
4956 | rsvd_check->rsvd_bits_mask[0][2] = high_bits_rsvd | rsvd_bits(3, 6) | large_1g_rsvd; |
4957 | rsvd_check->rsvd_bits_mask[0][1] = high_bits_rsvd | rsvd_bits(3, 6) | large_2m_rsvd; |
4958 | rsvd_check->rsvd_bits_mask[0][0] = high_bits_rsvd; |
4959 | |
4960 | /* large page */ |
4961 | rsvd_check->rsvd_bits_mask[1][4] = rsvd_check->rsvd_bits_mask[0][4]; |
4962 | rsvd_check->rsvd_bits_mask[1][3] = rsvd_check->rsvd_bits_mask[0][3]; |
4963 | rsvd_check->rsvd_bits_mask[1][2] = high_bits_rsvd | rsvd_bits(12, 29) | large_1g_rsvd; |
4964 | rsvd_check->rsvd_bits_mask[1][1] = high_bits_rsvd | rsvd_bits(12, 20) | large_2m_rsvd; |
4965 | rsvd_check->rsvd_bits_mask[1][0] = rsvd_check->rsvd_bits_mask[0][0]; |
4966 | |
4967 | bad_mt_xwr = 0xFFull << (2 * 8); /* bits 3..5 must not be 2 */ |
4968 | bad_mt_xwr |= 0xFFull << (3 * 8); /* bits 3..5 must not be 3 */ |
4969 | bad_mt_xwr |= 0xFFull << (7 * 8); /* bits 3..5 must not be 7 */ |
4970 | bad_mt_xwr |= REPEAT_BYTE(1ull << 2); /* bits 0..2 must not be 010 */ |
4971 | bad_mt_xwr |= REPEAT_BYTE(1ull << 6); /* bits 0..2 must not be 110 */ |
4972 | if (!execonly) { |
4973 | /* bits 0..2 must not be 100 unless VMX capabilities allow it */ |
4974 | bad_mt_xwr |= REPEAT_BYTE(1ull << 4); |
4975 | } |
4976 | rsvd_check->bad_mt_xwr = bad_mt_xwr; |
4977 | } |
4978 | |
4979 | static void reset_rsvds_bits_mask_ept(struct kvm_vcpu *vcpu, |
4980 | struct kvm_mmu *context, bool execonly, int huge_page_level) |
4981 | { |
4982 | __reset_rsvds_bits_mask_ept(rsvd_check: &context->guest_rsvd_check, |
4983 | pa_bits_rsvd: vcpu->arch.reserved_gpa_bits, execonly, |
4984 | huge_page_level); |
4985 | } |
4986 | |
4987 | static inline u64 reserved_hpa_bits(void) |
4988 | { |
4989 | return rsvd_bits(shadow_phys_bits, 63); |
4990 | } |
4991 | |
4992 | /* |
4993 | * the page table on host is the shadow page table for the page |
4994 | * table in guest or amd nested guest, its mmu features completely |
4995 | * follow the features in guest. |
4996 | */ |
4997 | static void reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, |
4998 | struct kvm_mmu *context) |
4999 | { |
5000 | /* @amd adds a check on bit of SPTEs, which KVM shouldn't use anyways. */ |
5001 | bool is_amd = true; |
5002 | /* KVM doesn't use 2-level page tables for the shadow MMU. */ |
5003 | bool is_pse = false; |
5004 | struct rsvd_bits_validate *shadow_zero_check; |
5005 | int i; |
5006 | |
5007 | WARN_ON_ONCE(context->root_role.level < PT32E_ROOT_LEVEL); |
5008 | |
5009 | shadow_zero_check = &context->shadow_zero_check; |
5010 | __reset_rsvds_bits_mask(rsvd_check: shadow_zero_check, pa_bits_rsvd: reserved_hpa_bits(), |
5011 | level: context->root_role.level, |
5012 | nx: context->root_role.efer_nx, |
5013 | gbpages: guest_can_use(vcpu, X86_FEATURE_GBPAGES), |
5014 | pse: is_pse, amd: is_amd); |
5015 | |
5016 | if (!shadow_me_mask) |
5017 | return; |
5018 | |
5019 | for (i = context->root_role.level; --i >= 0;) { |
5020 | /* |
5021 | * So far shadow_me_value is a constant during KVM's life |
5022 | * time. Bits in shadow_me_value are allowed to be set. |
5023 | * Bits in shadow_me_mask but not in shadow_me_value are |
5024 | * not allowed to be set. |
5025 | */ |
5026 | shadow_zero_check->rsvd_bits_mask[0][i] |= shadow_me_mask; |
5027 | shadow_zero_check->rsvd_bits_mask[1][i] |= shadow_me_mask; |
5028 | shadow_zero_check->rsvd_bits_mask[0][i] &= ~shadow_me_value; |
5029 | shadow_zero_check->rsvd_bits_mask[1][i] &= ~shadow_me_value; |
5030 | } |
5031 | |
5032 | } |
5033 | |
5034 | static inline bool boot_cpu_is_amd(void) |
5035 | { |
5036 | WARN_ON_ONCE(!tdp_enabled); |
5037 | return shadow_x_mask == 0; |
5038 | } |
5039 | |
5040 | /* |
5041 | * the direct page table on host, use as much mmu features as |
5042 | * possible, however, kvm currently does not do execution-protection. |
5043 | */ |
5044 | static void reset_tdp_shadow_zero_bits_mask(struct kvm_mmu *context) |
5045 | { |
5046 | struct rsvd_bits_validate *shadow_zero_check; |
5047 | int i; |
5048 | |
5049 | shadow_zero_check = &context->shadow_zero_check; |
5050 | |
5051 | if (boot_cpu_is_amd()) |
5052 | __reset_rsvds_bits_mask(rsvd_check: shadow_zero_check, pa_bits_rsvd: reserved_hpa_bits(), |
5053 | level: context->root_role.level, nx: true, |
5054 | boot_cpu_has(X86_FEATURE_GBPAGES), |
5055 | pse: false, amd: true); |
5056 | else |
5057 | __reset_rsvds_bits_mask_ept(rsvd_check: shadow_zero_check, |
5058 | pa_bits_rsvd: reserved_hpa_bits(), execonly: false, |
5059 | huge_page_level: max_huge_page_level); |
5060 | |
5061 | if (!shadow_me_mask) |
5062 | return; |
5063 | |
5064 | for (i = context->root_role.level; --i >= 0;) { |
5065 | shadow_zero_check->rsvd_bits_mask[0][i] &= ~shadow_me_mask; |
5066 | shadow_zero_check->rsvd_bits_mask[1][i] &= ~shadow_me_mask; |
5067 | } |
5068 | } |
5069 | |
5070 | /* |
5071 | * as the comments in reset_shadow_zero_bits_mask() except it |
5072 | * is the shadow page table for intel nested guest. |
5073 | */ |
5074 | static void |
5075 | reset_ept_shadow_zero_bits_mask(struct kvm_mmu *context, bool execonly) |
5076 | { |
5077 | __reset_rsvds_bits_mask_ept(rsvd_check: &context->shadow_zero_check, |
5078 | pa_bits_rsvd: reserved_hpa_bits(), execonly, |
5079 | huge_page_level: max_huge_page_level); |
5080 | } |
5081 | |
5082 | #define BYTE_MASK(access) \ |
5083 | ((1 & (access) ? 2 : 0) | \ |
5084 | (2 & (access) ? 4 : 0) | \ |
5085 | (3 & (access) ? 8 : 0) | \ |
5086 | (4 & (access) ? 16 : 0) | \ |
5087 | (5 & (access) ? 32 : 0) | \ |
5088 | (6 & (access) ? 64 : 0) | \ |
5089 | (7 & (access) ? 128 : 0)) |
5090 | |
5091 | |
5092 | static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept) |
5093 | { |
5094 | unsigned byte; |
5095 | |
5096 | const u8 x = BYTE_MASK(ACC_EXEC_MASK); |
5097 | const u8 w = BYTE_MASK(ACC_WRITE_MASK); |
5098 | const u8 u = BYTE_MASK(ACC_USER_MASK); |
5099 | |
5100 | bool cr4_smep = is_cr4_smep(mmu); |
5101 | bool cr4_smap = is_cr4_smap(mmu); |
5102 | bool cr0_wp = is_cr0_wp(mmu); |
5103 | bool efer_nx = is_efer_nx(mmu); |
5104 | |
5105 | for (byte = 0; byte < ARRAY_SIZE(mmu->permissions); ++byte) { |
5106 | unsigned pfec = byte << 1; |
5107 | |
5108 | /* |
5109 | * Each "*f" variable has a 1 bit for each UWX value |
5110 | * that causes a fault with the given PFEC. |
5111 | */ |
5112 | |
5113 | /* Faults from writes to non-writable pages */ |
5114 | u8 wf = (pfec & PFERR_WRITE_MASK) ? (u8)~w : 0; |
5115 | /* Faults from user mode accesses to supervisor pages */ |
5116 | u8 uf = (pfec & PFERR_USER_MASK) ? (u8)~u : 0; |
5117 | /* Faults from fetches of non-executable pages*/ |
5118 | u8 ff = (pfec & PFERR_FETCH_MASK) ? (u8)~x : 0; |
5119 | /* Faults from kernel mode fetches of user pages */ |
5120 | u8 smepf = 0; |
5121 | /* Faults from kernel mode accesses of user pages */ |
5122 | u8 smapf = 0; |
5123 | |
5124 | if (!ept) { |
5125 | /* Faults from kernel mode accesses to user pages */ |
5126 | u8 kf = (pfec & PFERR_USER_MASK) ? 0 : u; |
5127 | |
5128 | /* Not really needed: !nx will cause pte.nx to fault */ |
5129 | if (!efer_nx) |
5130 | ff = 0; |
5131 | |
5132 | /* Allow supervisor writes if !cr0.wp */ |
5133 | if (!cr0_wp) |
5134 | wf = (pfec & PFERR_USER_MASK) ? wf : 0; |
5135 | |
5136 | /* Disallow supervisor fetches of user code if cr4.smep */ |
5137 | if (cr4_smep) |
5138 | smepf = (pfec & PFERR_FETCH_MASK) ? kf : 0; |
5139 | |
5140 | /* |
5141 | * SMAP:kernel-mode data accesses from user-mode |
5142 | * mappings should fault. A fault is considered |
5143 | * as a SMAP violation if all of the following |
5144 | * conditions are true: |
5145 | * - X86_CR4_SMAP is set in CR4 |
5146 | * - A user page is accessed |
5147 | * - The access is not a fetch |
5148 | * - The access is supervisor mode |
5149 | * - If implicit supervisor access or X86_EFLAGS_AC is clear |
5150 | * |
5151 | * Here, we cover the first four conditions. |
5152 | * The fifth is computed dynamically in permission_fault(); |
5153 | * PFERR_RSVD_MASK bit will be set in PFEC if the access is |
5154 | * *not* subject to SMAP restrictions. |
5155 | */ |
5156 | if (cr4_smap) |
5157 | smapf = (pfec & (PFERR_RSVD_MASK|PFERR_FETCH_MASK)) ? 0 : kf; |
5158 | } |
5159 | |
5160 | mmu->permissions[byte] = ff | uf | wf | smepf | smapf; |
5161 | } |
5162 | } |
5163 | |
5164 | /* |
5165 | * PKU is an additional mechanism by which the paging controls access to |
5166 | * user-mode addresses based on the value in the PKRU register. Protection |
5167 | * key violations are reported through a bit in the page fault error code. |
5168 | * Unlike other bits of the error code, the PK bit is not known at the |
5169 | * call site of e.g. gva_to_gpa; it must be computed directly in |
5170 | * permission_fault based on two bits of PKRU, on some machine state (CR4, |
5171 | * CR0, EFER, CPL), and on other bits of the error code and the page tables. |
5172 | * |
5173 | * In particular the following conditions come from the error code, the |
5174 | * page tables and the machine state: |
5175 | * - PK is always zero unless CR4.PKE=1 and EFER.LMA=1 |
5176 | * - PK is always zero if RSVD=1 (reserved bit set) or F=1 (instruction fetch) |
5177 | * - PK is always zero if U=0 in the page tables |
5178 | * - PKRU.WD is ignored if CR0.WP=0 and the access is a supervisor access. |
5179 | * |
5180 | * The PKRU bitmask caches the result of these four conditions. The error |
5181 | * code (minus the P bit) and the page table's U bit form an index into the |
5182 | * PKRU bitmask. Two bits of the PKRU bitmask are then extracted and ANDed |
5183 | * with the two bits of the PKRU register corresponding to the protection key. |
5184 | * For the first three conditions above the bits will be 00, thus masking |
5185 | * away both AD and WD. For all reads or if the last condition holds, WD |
5186 | * only will be masked away. |
5187 | */ |
5188 | static void update_pkru_bitmask(struct kvm_mmu *mmu) |
5189 | { |
5190 | unsigned bit; |
5191 | bool wp; |
5192 | |
5193 | mmu->pkru_mask = 0; |
5194 | |
5195 | if (!is_cr4_pke(mmu)) |
5196 | return; |
5197 | |
5198 | wp = is_cr0_wp(mmu); |
5199 | |
5200 | for (bit = 0; bit < ARRAY_SIZE(mmu->permissions); ++bit) { |
5201 | unsigned pfec, pkey_bits; |
5202 | bool check_pkey, check_write, ff, uf, wf, pte_user; |
5203 | |
5204 | pfec = bit << 1; |
5205 | ff = pfec & PFERR_FETCH_MASK; |
5206 | uf = pfec & PFERR_USER_MASK; |
5207 | wf = pfec & PFERR_WRITE_MASK; |
5208 | |
5209 | /* PFEC.RSVD is replaced by ACC_USER_MASK. */ |
5210 | pte_user = pfec & PFERR_RSVD_MASK; |
5211 | |
5212 | /* |
5213 | * Only need to check the access which is not an |
5214 | * instruction fetch and is to a user page. |
5215 | */ |
5216 | check_pkey = (!ff && pte_user); |
5217 | /* |
5218 | * write access is controlled by PKRU if it is a |
5219 | * user access or CR0.WP = 1. |
5220 | */ |
5221 | check_write = check_pkey && wf && (uf || wp); |
5222 | |
5223 | /* PKRU.AD stops both read and write access. */ |
5224 | pkey_bits = !!check_pkey; |
5225 | /* PKRU.WD stops write access. */ |
5226 | pkey_bits |= (!!check_write) << 1; |
5227 | |
5228 | mmu->pkru_mask |= (pkey_bits & 3) << pfec; |
5229 | } |
5230 | } |
5231 | |
5232 | static void reset_guest_paging_metadata(struct kvm_vcpu *vcpu, |
5233 | struct kvm_mmu *mmu) |
5234 | { |
5235 | if (!is_cr0_pg(mmu)) |
5236 | return; |
5237 | |
5238 | reset_guest_rsvds_bits_mask(vcpu, context: mmu); |
5239 | update_permission_bitmask(mmu, ept: false); |
5240 | update_pkru_bitmask(mmu); |
5241 | } |
5242 | |
5243 | static void paging64_init_context(struct kvm_mmu *context) |
5244 | { |
5245 | context->page_fault = paging64_page_fault; |
5246 | context->gva_to_gpa = paging64_gva_to_gpa; |
5247 | context->sync_spte = paging64_sync_spte; |
5248 | } |
5249 | |
5250 | static void paging32_init_context(struct kvm_mmu *context) |
5251 | { |
5252 | context->page_fault = paging32_page_fault; |
5253 | context->gva_to_gpa = paging32_gva_to_gpa; |
5254 | context->sync_spte = paging32_sync_spte; |
5255 | } |
5256 | |
5257 | static union kvm_cpu_role kvm_calc_cpu_role(struct kvm_vcpu *vcpu, |
5258 | const struct kvm_mmu_role_regs *regs) |
5259 | { |
5260 | union kvm_cpu_role role = {0}; |
5261 | |
5262 | role.base.access = ACC_ALL; |
5263 | role.base.smm = is_smm(vcpu); |
5264 | role.base.guest_mode = is_guest_mode(vcpu); |
5265 | role.ext.valid = 1; |
5266 | |
5267 | if (!____is_cr0_pg(regs)) { |
5268 | role.base.direct = 1; |
5269 | return role; |
5270 | } |
5271 | |
5272 | role.base.efer_nx = ____is_efer_nx(regs); |
5273 | role.base.cr0_wp = ____is_cr0_wp(regs); |
5274 | role.base.smep_andnot_wp = ____is_cr4_smep(regs) && !____is_cr0_wp(regs); |
5275 | role.base.smap_andnot_wp = ____is_cr4_smap(regs) && !____is_cr0_wp(regs); |
5276 | role.base.has_4_byte_gpte = !____is_cr4_pae(regs); |
5277 | |
5278 | if (____is_efer_lma(regs)) |
5279 | role.base.level = ____is_cr4_la57(regs) ? PT64_ROOT_5LEVEL |
5280 | : PT64_ROOT_4LEVEL; |
5281 | else if (____is_cr4_pae(regs)) |
5282 | role.base.level = PT32E_ROOT_LEVEL; |
5283 | else |
5284 | role.base.level = PT32_ROOT_LEVEL; |
5285 | |
5286 | role.ext.cr4_smep = ____is_cr4_smep(regs); |
5287 | role.ext.cr4_smap = ____is_cr4_smap(regs); |
5288 | role.ext.cr4_pse = ____is_cr4_pse(regs); |
5289 | |
5290 | /* PKEY and LA57 are active iff long mode is active. */ |
5291 | role.ext.cr4_pke = ____is_efer_lma(regs) && ____is_cr4_pke(regs); |
5292 | role.ext.cr4_la57 = ____is_efer_lma(regs) && ____is_cr4_la57(regs); |
5293 | role.ext.efer_lma = ____is_efer_lma(regs); |
5294 | return role; |
5295 | } |
5296 | |
5297 | void __kvm_mmu_refresh_passthrough_bits(struct kvm_vcpu *vcpu, |
5298 | struct kvm_mmu *mmu) |
5299 | { |
5300 | const bool cr0_wp = kvm_is_cr0_bit_set(vcpu, X86_CR0_WP); |
5301 | |
5302 | BUILD_BUG_ON((KVM_MMU_CR0_ROLE_BITS & KVM_POSSIBLE_CR0_GUEST_BITS) != X86_CR0_WP); |
5303 | BUILD_BUG_ON((KVM_MMU_CR4_ROLE_BITS & KVM_POSSIBLE_CR4_GUEST_BITS)); |
5304 | |
5305 | if (is_cr0_wp(mmu) == cr0_wp) |
5306 | return; |
5307 | |
5308 | mmu->cpu_role.base.cr0_wp = cr0_wp; |
5309 | reset_guest_paging_metadata(vcpu, mmu); |
5310 | } |
5311 | |
5312 | static inline int kvm_mmu_get_tdp_level(struct kvm_vcpu *vcpu) |
5313 | { |
5314 | /* tdp_root_level is architecture forced level, use it if nonzero */ |
5315 | if (tdp_root_level) |
5316 | return tdp_root_level; |
5317 | |
5318 | /* Use 5-level TDP if and only if it's useful/necessary. */ |
5319 | if (max_tdp_level == 5 && cpuid_maxphyaddr(vcpu) <= 48) |
5320 | return 4; |
5321 | |
5322 | return max_tdp_level; |
5323 | } |
5324 | |
5325 | static union kvm_mmu_page_role |
5326 | kvm_calc_tdp_mmu_root_page_role(struct kvm_vcpu *vcpu, |
5327 | union kvm_cpu_role cpu_role) |
5328 | { |
5329 | union kvm_mmu_page_role role = {0}; |
5330 | |
5331 | role.access = ACC_ALL; |
5332 | role.cr0_wp = true; |
5333 | role.efer_nx = true; |
5334 | role.smm = cpu_role.base.smm; |
5335 | role.guest_mode = cpu_role.base.guest_mode; |
5336 | role.ad_disabled = !kvm_ad_enabled(); |
5337 | role.level = kvm_mmu_get_tdp_level(vcpu); |
5338 | role.direct = true; |
5339 | role.has_4_byte_gpte = false; |
5340 | |
5341 | return role; |
5342 | } |
5343 | |
5344 | static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu, |
5345 | union kvm_cpu_role cpu_role) |
5346 | { |
5347 | struct kvm_mmu *context = &vcpu->arch.root_mmu; |
5348 | union kvm_mmu_page_role root_role = kvm_calc_tdp_mmu_root_page_role(vcpu, cpu_role); |
5349 | |
5350 | if (cpu_role.as_u64 == context->cpu_role.as_u64 && |
5351 | root_role.word == context->root_role.word) |
5352 | return; |
5353 | |
5354 | context->cpu_role.as_u64 = cpu_role.as_u64; |
5355 | context->root_role.word = root_role.word; |
5356 | context->page_fault = kvm_tdp_page_fault; |
5357 | context->sync_spte = NULL; |
5358 | context->get_guest_pgd = get_guest_cr3; |
5359 | context->get_pdptr = kvm_pdptr_read; |
5360 | context->inject_page_fault = kvm_inject_page_fault; |
5361 | |
5362 | if (!is_cr0_pg(mmu: context)) |
5363 | context->gva_to_gpa = nonpaging_gva_to_gpa; |
5364 | else if (is_cr4_pae(mmu: context)) |
5365 | context->gva_to_gpa = paging64_gva_to_gpa; |
5366 | else |
5367 | context->gva_to_gpa = paging32_gva_to_gpa; |
5368 | |
5369 | reset_guest_paging_metadata(vcpu, mmu: context); |
5370 | reset_tdp_shadow_zero_bits_mask(context); |
5371 | } |
5372 | |
5373 | static void shadow_mmu_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *context, |
5374 | union kvm_cpu_role cpu_role, |
5375 | union kvm_mmu_page_role root_role) |
5376 | { |
5377 | if (cpu_role.as_u64 == context->cpu_role.as_u64 && |
5378 | root_role.word == context->root_role.word) |
5379 | return; |
5380 | |
5381 | context->cpu_role.as_u64 = cpu_role.as_u64; |
5382 | context->root_role.word = root_role.word; |
5383 | |
5384 | if (!is_cr0_pg(mmu: context)) |
5385 | nonpaging_init_context(context); |
5386 | else if (is_cr4_pae(mmu: context)) |
5387 | paging64_init_context(context); |
5388 | else |
5389 | paging32_init_context(context); |
5390 | |
5391 | reset_guest_paging_metadata(vcpu, mmu: context); |
5392 | reset_shadow_zero_bits_mask(vcpu, context); |
5393 | } |
5394 | |
5395 | static void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, |
5396 | union kvm_cpu_role cpu_role) |
5397 | { |
5398 | struct kvm_mmu *context = &vcpu->arch.root_mmu; |
5399 | union kvm_mmu_page_role root_role; |
5400 | |
5401 | root_role = cpu_role.base; |
5402 | |
5403 | /* KVM uses PAE paging whenever the guest isn't using 64-bit paging. */ |
5404 | root_role.level = max_t(u32, root_role.level, PT32E_ROOT_LEVEL); |
5405 | |
5406 | /* |
5407 | * KVM forces EFER.NX=1 when TDP is disabled, reflect it in the MMU role. |
5408 | * KVM uses NX when TDP is disabled to handle a variety of scenarios, |
5409 | * notably for huge SPTEs if iTLB multi-hit mitigation is enabled and |
5410 | * to generate correct permissions for CR0.WP=0/CR4.SMEP=1/EFER.NX=0. |
5411 | * The iTLB multi-hit workaround can be toggled at any time, so assume |
5412 | * NX can be used by any non-nested shadow MMU to avoid having to reset |
5413 | * MMU contexts. |
5414 | */ |
5415 | root_role.efer_nx = true; |
5416 | |
5417 | shadow_mmu_init_context(vcpu, context, cpu_role, root_role); |
5418 | } |
5419 | |
5420 | void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0, |
5421 | unsigned long cr4, u64 efer, gpa_t nested_cr3) |
5422 | { |
5423 | struct kvm_mmu *context = &vcpu->arch.guest_mmu; |
5424 | struct kvm_mmu_role_regs regs = { |
5425 | .cr0 = cr0, |
5426 | .cr4 = cr4 & ~X86_CR4_PKE, |
5427 | .efer = efer, |
5428 | }; |
5429 | union kvm_cpu_role cpu_role = kvm_calc_cpu_role(vcpu, regs: ®s); |
5430 | union kvm_mmu_page_role root_role; |
5431 | |
5432 | /* NPT requires CR0.PG=1. */ |
5433 | WARN_ON_ONCE(cpu_role.base.direct); |
5434 | |
5435 | root_role = cpu_role.base; |
5436 | root_role.level = kvm_mmu_get_tdp_level(vcpu); |
5437 | if (root_role.level == PT64_ROOT_5LEVEL && |
5438 | cpu_role.base.level == PT64_ROOT_4LEVEL) |
5439 | root_role.passthrough = 1; |
5440 | |
5441 | shadow_mmu_init_context(vcpu, context, cpu_role, root_role); |
5442 | kvm_mmu_new_pgd(vcpu, nested_cr3); |
5443 | } |
5444 | EXPORT_SYMBOL_GPL(kvm_init_shadow_npt_mmu); |
5445 | |
5446 | static union kvm_cpu_role |
5447 | kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty, |
5448 | bool execonly, u8 level) |
5449 | { |
5450 | union kvm_cpu_role role = {0}; |
5451 | |
5452 | /* |
5453 | * KVM does not support SMM transfer monitors, and consequently does not |
5454 | * support the "entry to SMM" control either. role.base.smm is always 0. |
5455 | */ |
5456 | WARN_ON_ONCE(is_smm(vcpu)); |
5457 | role.base.level = level; |
5458 | role.base.has_4_byte_gpte = false; |
5459 | role.base.direct = false; |
5460 | role.base.ad_disabled = !accessed_dirty; |
5461 | role.base.guest_mode = true; |
5462 | role.base.access = ACC_ALL; |
5463 | |
5464 | role.ext.word = 0; |
5465 | role.ext.execonly = execonly; |
5466 | role.ext.valid = 1; |
5467 | |
5468 | return role; |
5469 | } |
5470 | |
5471 | void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly, |
5472 | int huge_page_level, bool accessed_dirty, |
5473 | gpa_t new_eptp) |
5474 | { |
5475 | struct kvm_mmu *context = &vcpu->arch.guest_mmu; |
5476 | u8 level = vmx_eptp_page_walk_level(eptp: new_eptp); |
5477 | union kvm_cpu_role new_mode = |
5478 | kvm_calc_shadow_ept_root_page_role(vcpu, accessed_dirty, |
5479 | execonly, level); |
5480 | |
5481 | if (new_mode.as_u64 != context->cpu_role.as_u64) { |
5482 | /* EPT, and thus nested EPT, does not consume CR0, CR4, nor EFER. */ |
5483 | context->cpu_role.as_u64 = new_mode.as_u64; |
5484 | context->root_role.word = new_mode.base.word; |
5485 | |
5486 | context->page_fault = ept_page_fault; |
5487 | context->gva_to_gpa = ept_gva_to_gpa; |
5488 | context->sync_spte = ept_sync_spte; |
5489 | |
5490 | update_permission_bitmask(mmu: context, ept: true); |
5491 | context->pkru_mask = 0; |
5492 | reset_rsvds_bits_mask_ept(vcpu, context, execonly, huge_page_level); |
5493 | reset_ept_shadow_zero_bits_mask(context, execonly); |
5494 | } |
5495 | |
5496 | kvm_mmu_new_pgd(vcpu, new_eptp); |
5497 | } |
5498 | EXPORT_SYMBOL_GPL(kvm_init_shadow_ept_mmu); |
5499 | |
5500 | static void init_kvm_softmmu(struct kvm_vcpu *vcpu, |
5501 | union kvm_cpu_role cpu_role) |
5502 | { |
5503 | struct kvm_mmu *context = &vcpu->arch.root_mmu; |
5504 | |
5505 | kvm_init_shadow_mmu(vcpu, cpu_role); |
5506 | |
5507 | context->get_guest_pgd = get_guest_cr3; |
5508 | context->get_pdptr = kvm_pdptr_read; |
5509 | context->inject_page_fault = kvm_inject_page_fault; |
5510 | } |
5511 | |
5512 | static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu, |
5513 | union kvm_cpu_role new_mode) |
5514 | { |
5515 | struct kvm_mmu *g_context = &vcpu->arch.nested_mmu; |
5516 | |
5517 | if (new_mode.as_u64 == g_context->cpu_role.as_u64) |
5518 | return; |
5519 | |
5520 | g_context->cpu_role.as_u64 = new_mode.as_u64; |
5521 | g_context->get_guest_pgd = get_guest_cr3; |
5522 | g_context->get_pdptr = kvm_pdptr_read; |
5523 | g_context->inject_page_fault = kvm_inject_page_fault; |
5524 | |
5525 | /* |
5526 | * L2 page tables are never shadowed, so there is no need to sync |
5527 | * SPTEs. |
5528 | */ |
5529 | g_context->sync_spte = NULL; |
5530 | |
5531 | /* |
5532 | * Note that arch.mmu->gva_to_gpa translates l2_gpa to l1_gpa using |
5533 | * L1's nested page tables (e.g. EPT12). The nested translation |
5534 | * of l2_gva to l1_gpa is done by arch.nested_mmu.gva_to_gpa using |
5535 | * L2's page tables as the first level of translation and L1's |
5536 | * nested page tables as the second level of translation. Basically |
5537 | * the gva_to_gpa functions between mmu and nested_mmu are swapped. |
5538 | */ |
5539 | if (!is_paging(vcpu)) |
5540 | g_context->gva_to_gpa = nonpaging_gva_to_gpa; |
5541 | else if (is_long_mode(vcpu)) |
5542 | g_context->gva_to_gpa = paging64_gva_to_gpa; |
5543 | else if (is_pae(vcpu)) |
5544 | g_context->gva_to_gpa = paging64_gva_to_gpa; |
5545 | else |
5546 | g_context->gva_to_gpa = paging32_gva_to_gpa; |
5547 | |
5548 | reset_guest_paging_metadata(vcpu, mmu: g_context); |
5549 | } |
5550 | |
5551 | void kvm_init_mmu(struct kvm_vcpu *vcpu) |
5552 | { |
5553 | struct kvm_mmu_role_regs regs = vcpu_to_role_regs(vcpu); |
5554 | union kvm_cpu_role cpu_role = kvm_calc_cpu_role(vcpu, regs: ®s); |
5555 | |
5556 | if (mmu_is_nested(vcpu)) |
5557 | init_kvm_nested_mmu(vcpu, new_mode: cpu_role); |
5558 | else if (tdp_enabled) |
5559 | init_kvm_tdp_mmu(vcpu, cpu_role); |
5560 | else |
5561 | init_kvm_softmmu(vcpu, cpu_role); |
5562 | } |
5563 | EXPORT_SYMBOL_GPL(kvm_init_mmu); |
5564 | |
5565 | void kvm_mmu_after_set_cpuid(struct kvm_vcpu *vcpu) |
5566 | { |
5567 | /* |
5568 | * Invalidate all MMU roles to force them to reinitialize as CPUID |
5569 | * information is factored into reserved bit calculations. |
5570 | * |
5571 | * Correctly handling multiple vCPU models with respect to paging and |
5572 | * physical address properties) in a single VM would require tracking |
5573 | * all relevant CPUID information in kvm_mmu_page_role. That is very |
5574 | * undesirable as it would increase the memory requirements for |
5575 | * gfn_write_track (see struct kvm_mmu_page_role comments). For now |
5576 | * that problem is swept under the rug; KVM's CPUID API is horrific and |
5577 | * it's all but impossible to solve it without introducing a new API. |
5578 | */ |
5579 | vcpu->arch.root_mmu.root_role.invalid = 1; |
5580 | vcpu->arch.guest_mmu.root_role.invalid = 1; |
5581 | vcpu->arch.nested_mmu.root_role.invalid = 1; |
5582 | vcpu->arch.root_mmu.cpu_role.ext.valid = 0; |
5583 | vcpu->arch.guest_mmu.cpu_role.ext.valid = 0; |
5584 | vcpu->arch.nested_mmu.cpu_role.ext.valid = 0; |
5585 | kvm_mmu_reset_context(vcpu); |
5586 | |
5587 | /* |
5588 | * Changing guest CPUID after KVM_RUN is forbidden, see the comment in |
5589 | * kvm_arch_vcpu_ioctl(). |
5590 | */ |
5591 | KVM_BUG_ON(kvm_vcpu_has_run(vcpu), vcpu->kvm); |
5592 | } |
5593 | |
5594 | void kvm_mmu_reset_context(struct kvm_vcpu *vcpu) |
5595 | { |
5596 | kvm_mmu_unload(vcpu); |
5597 | kvm_init_mmu(vcpu); |
5598 | } |
5599 | EXPORT_SYMBOL_GPL(kvm_mmu_reset_context); |
5600 | |
5601 | int kvm_mmu_load(struct kvm_vcpu *vcpu) |
5602 | { |
5603 | int r; |
5604 | |
5605 | r = mmu_topup_memory_caches(vcpu, maybe_indirect: !vcpu->arch.mmu->root_role.direct); |
5606 | if (r) |
5607 | goto out; |
5608 | r = mmu_alloc_special_roots(vcpu); |
5609 | if (r) |
5610 | goto out; |
5611 | if (vcpu->arch.mmu->root_role.direct) |
5612 | r = mmu_alloc_direct_roots(vcpu); |
5613 | else |
5614 | r = mmu_alloc_shadow_roots(vcpu); |
5615 | if (r) |
5616 | goto out; |
5617 | |
5618 | kvm_mmu_sync_roots(vcpu); |
5619 | |
5620 | kvm_mmu_load_pgd(vcpu); |
5621 | |
5622 | /* |
5623 | * Flush any TLB entries for the new root, the provenance of the root |
5624 | * is unknown. Even if KVM ensures there are no stale TLB entries |
5625 | * for a freed root, in theory another hypervisor could have left |
5626 | * stale entries. Flushing on alloc also allows KVM to skip the TLB |
5627 | * flush when freeing a root (see kvm_tdp_mmu_put_root()). |
5628 | */ |
5629 | static_call(kvm_x86_flush_tlb_current)(vcpu); |
5630 | out: |
5631 | return r; |
5632 | } |
5633 | |
5634 | void kvm_mmu_unload(struct kvm_vcpu *vcpu) |
5635 | { |
5636 | struct kvm *kvm = vcpu->kvm; |
5637 | |
5638 | kvm_mmu_free_roots(kvm, &vcpu->arch.root_mmu, KVM_MMU_ROOTS_ALL); |
5639 | WARN_ON_ONCE(VALID_PAGE(vcpu->arch.root_mmu.root.hpa)); |
5640 | kvm_mmu_free_roots(kvm, &vcpu->arch.guest_mmu, KVM_MMU_ROOTS_ALL); |
5641 | WARN_ON_ONCE(VALID_PAGE(vcpu->arch.guest_mmu.root.hpa)); |
5642 | vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); |
5643 | } |
5644 | |
5645 | static bool is_obsolete_root(struct kvm *kvm, hpa_t root_hpa) |
5646 | { |
5647 | struct kvm_mmu_page *sp; |
5648 | |
5649 | if (!VALID_PAGE(root_hpa)) |
5650 | return false; |
5651 | |
5652 | /* |
5653 | * When freeing obsolete roots, treat roots as obsolete if they don't |
5654 | * have an associated shadow page, as it's impossible to determine if |
5655 | * such roots are fresh or stale. This does mean KVM will get false |
5656 | * positives and free roots that don't strictly need to be freed, but |
5657 | * such false positives are relatively rare: |
5658 | * |
5659 | * (a) only PAE paging and nested NPT have roots without shadow pages |
5660 | * (or any shadow paging flavor with a dummy root, see note below) |
5661 | * (b) remote reloads due to a memslot update obsoletes _all_ roots |
5662 | * (c) KVM doesn't track previous roots for PAE paging, and the guest |
5663 | * is unlikely to zap an in-use PGD. |
5664 | * |
5665 | * Note! Dummy roots are unique in that they are obsoleted by memslot |
5666 | * _creation_! See also FNAME(fetch). |
5667 | */ |
5668 | sp = root_to_sp(root: root_hpa); |
5669 | return !sp || is_obsolete_sp(kvm, sp); |
5670 | } |
5671 | |
5672 | static void __kvm_mmu_free_obsolete_roots(struct kvm *kvm, struct kvm_mmu *mmu) |
5673 | { |
5674 | unsigned long roots_to_free = 0; |
5675 | int i; |
5676 | |
5677 | if (is_obsolete_root(kvm, root_hpa: mmu->root.hpa)) |
5678 | roots_to_free |= KVM_MMU_ROOT_CURRENT; |
5679 | |
5680 | for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { |
5681 | if (is_obsolete_root(kvm, root_hpa: mmu->prev_roots[i].hpa)) |
5682 | roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); |
5683 | } |
5684 | |
5685 | if (roots_to_free) |
5686 | kvm_mmu_free_roots(kvm, mmu, roots_to_free); |
5687 | } |
5688 | |
5689 | void kvm_mmu_free_obsolete_roots(struct kvm_vcpu *vcpu) |
5690 | { |
5691 | __kvm_mmu_free_obsolete_roots(kvm: vcpu->kvm, mmu: &vcpu->arch.root_mmu); |
5692 | __kvm_mmu_free_obsolete_roots(kvm: vcpu->kvm, mmu: &vcpu->arch.guest_mmu); |
5693 | } |
5694 | |
5695 | static u64 mmu_pte_write_fetch_gpte(struct kvm_vcpu *vcpu, gpa_t *gpa, |
5696 | int *bytes) |
5697 | { |
5698 | u64 gentry = 0; |
5699 | int r; |
5700 | |
5701 | /* |
5702 | * Assume that the pte write on a page table of the same type |
5703 | * as the current vcpu paging mode since we update the sptes only |
5704 | * when they have the same mode. |
5705 | */ |
5706 | if (is_pae(vcpu) && *bytes == 4) { |
5707 | /* Handle a 32-bit guest writing two halves of a 64-bit gpte */ |
5708 | *gpa &= ~(gpa_t)7; |
5709 | *bytes = 8; |
5710 | } |
5711 | |
5712 | if (*bytes == 4 || *bytes == 8) { |
5713 | r = kvm_vcpu_read_guest_atomic(vcpu, gpa: *gpa, data: &gentry, len: *bytes); |
5714 | if (r) |
5715 | gentry = 0; |
5716 | } |
5717 | |
5718 | return gentry; |
5719 | } |
5720 | |
5721 | /* |
5722 | * If we're seeing too many writes to a page, it may no longer be a page table, |
5723 | * or we may be forking, in which case it is better to unmap the page. |
5724 | */ |
5725 | static bool detect_write_flooding(struct kvm_mmu_page *sp) |
5726 | { |
5727 | /* |
5728 | * Skip write-flooding detected for the sp whose level is 1, because |
5729 | * it can become unsync, then the guest page is not write-protected. |
5730 | */ |
5731 | if (sp->role.level == PG_LEVEL_4K) |
5732 | return false; |
5733 | |
5734 | atomic_inc(v: &sp->write_flooding_count); |
5735 | return atomic_read(v: &sp->write_flooding_count) >= 3; |
5736 | } |
5737 | |
5738 | /* |
5739 | * Misaligned accesses are too much trouble to fix up; also, they usually |
5740 | * indicate a page is not used as a page table. |
5741 | */ |
5742 | static bool detect_write_misaligned(struct kvm_mmu_page *sp, gpa_t gpa, |
5743 | int bytes) |
5744 | { |
5745 | unsigned offset, pte_size, misaligned; |
5746 | |
5747 | offset = offset_in_page(gpa); |
5748 | pte_size = sp->role.has_4_byte_gpte ? 4 : 8; |
5749 | |
5750 | /* |
5751 | * Sometimes, the OS only writes the last one bytes to update status |
5752 | * bits, for example, in linux, andb instruction is used in clear_bit(). |
5753 | */ |
5754 | if (!(offset & (pte_size - 1)) && bytes == 1) |
5755 | return false; |
5756 | |
5757 | misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1); |
5758 | misaligned |= bytes < 4; |
5759 | |
5760 | return misaligned; |
5761 | } |
5762 | |
5763 | static u64 *get_written_sptes(struct kvm_mmu_page *sp, gpa_t gpa, int *nspte) |
5764 | { |
5765 | unsigned page_offset, quadrant; |
5766 | u64 *spte; |
5767 | int level; |
5768 | |
5769 | page_offset = offset_in_page(gpa); |
5770 | level = sp->role.level; |
5771 | *nspte = 1; |
5772 | if (sp->role.has_4_byte_gpte) { |
5773 | page_offset <<= 1; /* 32->64 */ |
5774 | /* |
5775 | * A 32-bit pde maps 4MB while the shadow pdes map |
5776 | * only 2MB. So we need to double the offset again |
5777 | * and zap two pdes instead of one. |
5778 | */ |
5779 | if (level == PT32_ROOT_LEVEL) { |
5780 | page_offset &= ~7; /* kill rounding error */ |
5781 | page_offset <<= 1; |
5782 | *nspte = 2; |
5783 | } |
5784 | quadrant = page_offset >> PAGE_SHIFT; |
5785 | page_offset &= ~PAGE_MASK; |
5786 | if (quadrant != sp->role.quadrant) |
5787 | return NULL; |
5788 | } |
5789 | |
5790 | spte = &sp->spt[page_offset / sizeof(*spte)]; |
5791 | return spte; |
5792 | } |
5793 | |
5794 | void kvm_mmu_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, |
5795 | int bytes) |
5796 | { |
5797 | gfn_t gfn = gpa >> PAGE_SHIFT; |
5798 | struct kvm_mmu_page *sp; |
5799 | LIST_HEAD(invalid_list); |
5800 | u64 entry, gentry, *spte; |
5801 | int npte; |
5802 | bool flush = false; |
5803 | |
5804 | /* |
5805 | * If we don't have indirect shadow pages, it means no page is |
5806 | * write-protected, so we can exit simply. |
5807 | */ |
5808 | if (!READ_ONCE(vcpu->kvm->arch.indirect_shadow_pages)) |
5809 | return; |
5810 | |
5811 | write_lock(&vcpu->kvm->mmu_lock); |
5812 | |
5813 | gentry = mmu_pte_write_fetch_gpte(vcpu, gpa: &gpa, bytes: &bytes); |
5814 | |
5815 | ++vcpu->kvm->stat.mmu_pte_write; |
5816 | |
5817 | for_each_gfn_valid_sp_with_gptes(vcpu->kvm, sp, gfn) { |
5818 | if (detect_write_misaligned(sp, gpa, bytes) || |
5819 | detect_write_flooding(sp)) { |
5820 | kvm_mmu_prepare_zap_page(kvm: vcpu->kvm, sp, invalid_list: &invalid_list); |
5821 | ++vcpu->kvm->stat.mmu_flooded; |
5822 | continue; |
5823 | } |
5824 | |
5825 | spte = get_written_sptes(sp, gpa, nspte: &npte); |
5826 | if (!spte) |
5827 | continue; |
5828 | |
5829 | while (npte--) { |
5830 | entry = *spte; |
5831 | mmu_page_zap_pte(kvm: vcpu->kvm, sp, spte, NULL); |
5832 | if (gentry && sp->role.level != PG_LEVEL_4K) |
5833 | ++vcpu->kvm->stat.mmu_pde_zapped; |
5834 | if (is_shadow_present_pte(pte: entry)) |
5835 | flush = true; |
5836 | ++spte; |
5837 | } |
5838 | } |
5839 | kvm_mmu_remote_flush_or_zap(kvm: vcpu->kvm, invalid_list: &invalid_list, remote_flush: flush); |
5840 | write_unlock(&vcpu->kvm->mmu_lock); |
5841 | } |
5842 | |
5843 | int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code, |
5844 | void *insn, int insn_len) |
5845 | { |
5846 | int r, emulation_type = EMULTYPE_PF; |
5847 | bool direct = vcpu->arch.mmu->root_role.direct; |
5848 | |
5849 | /* |
5850 | * IMPLICIT_ACCESS is a KVM-defined flag used to correctly perform SMAP |
5851 | * checks when emulating instructions that triggers implicit access. |
5852 | * WARN if hardware generates a fault with an error code that collides |
5853 | * with the KVM-defined value. Clear the flag and continue on, i.e. |
5854 | * don't terminate the VM, as KVM can't possibly be relying on a flag |
5855 | * that KVM doesn't know about. |
5856 | */ |
5857 | if (WARN_ON_ONCE(error_code & PFERR_IMPLICIT_ACCESS)) |
5858 | error_code &= ~PFERR_IMPLICIT_ACCESS; |
5859 | |
5860 | if (WARN_ON_ONCE(!VALID_PAGE(vcpu->arch.mmu->root.hpa))) |
5861 | return RET_PF_RETRY; |
5862 | |
5863 | r = RET_PF_INVALID; |
5864 | if (unlikely(error_code & PFERR_RSVD_MASK)) { |
5865 | r = handle_mmio_page_fault(vcpu, addr: cr2_or_gpa, direct); |
5866 | if (r == RET_PF_EMULATE) |
5867 | goto emulate; |
5868 | } |
5869 | |
5870 | if (r == RET_PF_INVALID) { |
5871 | r = kvm_mmu_do_page_fault(vcpu, cr2_or_gpa, |
5872 | lower_32_bits(error_code), prefetch: false, |
5873 | emulation_type: &emulation_type); |
5874 | if (KVM_BUG_ON(r == RET_PF_INVALID, vcpu->kvm)) |
5875 | return -EIO; |
5876 | } |
5877 | |
5878 | if (r < 0) |
5879 | return r; |
5880 | if (r != RET_PF_EMULATE) |
5881 | return 1; |
5882 | |
5883 | /* |
5884 | * Before emulating the instruction, check if the error code |
5885 | * was due to a RO violation while translating the guest page. |
5886 | * This can occur when using nested virtualization with nested |
5887 | * paging in both guests. If true, we simply unprotect the page |
5888 | * and resume the guest. |
5889 | */ |
5890 | if (vcpu->arch.mmu->root_role.direct && |
5891 | (error_code & PFERR_NESTED_GUEST_PAGE) == PFERR_NESTED_GUEST_PAGE) { |
5892 | kvm_mmu_unprotect_page(kvm: vcpu->kvm, gfn: gpa_to_gfn(gpa: cr2_or_gpa)); |
5893 | return 1; |
5894 | } |
5895 | |
5896 | /* |
5897 | * vcpu->arch.mmu.page_fault returned RET_PF_EMULATE, but we can still |
5898 | * optimistically try to just unprotect the page and let the processor |
5899 | * re-execute the instruction that caused the page fault. Do not allow |
5900 | * retrying MMIO emulation, as it's not only pointless but could also |
5901 | * cause us to enter an infinite loop because the processor will keep |
5902 | * faulting on the non-existent MMIO address. Retrying an instruction |
5903 | * from a nested guest is also pointless and dangerous as we are only |
5904 | * explicitly shadowing L1's page tables, i.e. unprotecting something |
5905 | * for L1 isn't going to magically fix whatever issue cause L2 to fail. |
5906 | */ |
5907 | if (!mmio_info_in_cache(vcpu, addr: cr2_or_gpa, direct) && !is_guest_mode(vcpu)) |
5908 | emulation_type |= EMULTYPE_ALLOW_RETRY_PF; |
5909 | emulate: |
5910 | return x86_emulate_instruction(vcpu, cr2_or_gpa, emulation_type, insn, |
5911 | insn_len); |
5912 | } |
5913 | EXPORT_SYMBOL_GPL(kvm_mmu_page_fault); |
5914 | |
5915 | static void __kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, |
5916 | u64 addr, hpa_t root_hpa) |
5917 | { |
5918 | struct kvm_shadow_walk_iterator iterator; |
5919 | |
5920 | vcpu_clear_mmio_info(vcpu, addr); |
5921 | |
5922 | /* |
5923 | * Walking and synchronizing SPTEs both assume they are operating in |
5924 | * the context of the current MMU, and would need to be reworked if |
5925 | * this is ever used to sync the guest_mmu, e.g. to emulate INVEPT. |
5926 | */ |
5927 | if (WARN_ON_ONCE(mmu != vcpu->arch.mmu)) |
5928 | return; |
5929 | |
5930 | if (!VALID_PAGE(root_hpa)) |
5931 | return; |
5932 | |
5933 | write_lock(&vcpu->kvm->mmu_lock); |
5934 | for_each_shadow_entry_using_root(vcpu, root_hpa, addr, iterator) { |
5935 | struct kvm_mmu_page *sp = sptep_to_sp(sptep: iterator.sptep); |
5936 | |
5937 | if (sp->unsync) { |
5938 | int ret = kvm_sync_spte(vcpu, sp, i: iterator.index); |
5939 | |
5940 | if (ret < 0) |
5941 | mmu_page_zap_pte(kvm: vcpu->kvm, sp, spte: iterator.sptep, NULL); |
5942 | if (ret) |
5943 | kvm_flush_remote_tlbs_sptep(kvm: vcpu->kvm, sptep: iterator.sptep); |
5944 | } |
5945 | |
5946 | if (!sp->unsync_children) |
5947 | break; |
5948 | } |
5949 | write_unlock(&vcpu->kvm->mmu_lock); |
5950 | } |
5951 | |
5952 | void kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, |
5953 | u64 addr, unsigned long roots) |
5954 | { |
5955 | int i; |
5956 | |
5957 | WARN_ON_ONCE(roots & ~KVM_MMU_ROOTS_ALL); |
5958 | |
5959 | /* It's actually a GPA for vcpu->arch.guest_mmu. */ |
5960 | if (mmu != &vcpu->arch.guest_mmu) { |
5961 | /* INVLPG on a non-canonical address is a NOP according to the SDM. */ |
5962 | if (is_noncanonical_address(addr, vcpu)) |
5963 | return; |
5964 | |
5965 | static_call(kvm_x86_flush_tlb_gva)(vcpu, addr); |
5966 | } |
5967 | |
5968 | if (!mmu->sync_spte) |
5969 | return; |
5970 | |
5971 | if (roots & KVM_MMU_ROOT_CURRENT) |
5972 | __kvm_mmu_invalidate_addr(vcpu, mmu, addr, root_hpa: mmu->root.hpa); |
5973 | |
5974 | for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { |
5975 | if (roots & KVM_MMU_ROOT_PREVIOUS(i)) |
5976 | __kvm_mmu_invalidate_addr(vcpu, mmu, addr, root_hpa: mmu->prev_roots[i].hpa); |
5977 | } |
5978 | } |
5979 | EXPORT_SYMBOL_GPL(kvm_mmu_invalidate_addr); |
5980 | |
5981 | void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva) |
5982 | { |
5983 | /* |
5984 | * INVLPG is required to invalidate any global mappings for the VA, |
5985 | * irrespective of PCID. Blindly sync all roots as it would take |
5986 | * roughly the same amount of work/time to determine whether any of the |
5987 | * previous roots have a global mapping. |
5988 | * |
5989 | * Mappings not reachable via the current or previous cached roots will |
5990 | * be synced when switching to that new cr3, so nothing needs to be |
5991 | * done here for them. |
5992 | */ |
5993 | kvm_mmu_invalidate_addr(vcpu, vcpu->arch.walk_mmu, gva, KVM_MMU_ROOTS_ALL); |
5994 | ++vcpu->stat.invlpg; |
5995 | } |
5996 | EXPORT_SYMBOL_GPL(kvm_mmu_invlpg); |
5997 | |
5998 | |
5999 | void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid) |
6000 | { |
6001 | struct kvm_mmu *mmu = vcpu->arch.mmu; |
6002 | unsigned long roots = 0; |
6003 | uint i; |
6004 | |
6005 | if (pcid == kvm_get_active_pcid(vcpu)) |
6006 | roots |= KVM_MMU_ROOT_CURRENT; |
6007 | |
6008 | for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { |
6009 | if (VALID_PAGE(mmu->prev_roots[i].hpa) && |
6010 | pcid == kvm_get_pcid(vcpu, mmu->prev_roots[i].pgd)) |
6011 | roots |= KVM_MMU_ROOT_PREVIOUS(i); |
6012 | } |
6013 | |
6014 | if (roots) |
6015 | kvm_mmu_invalidate_addr(vcpu, mmu, gva, roots); |
6016 | ++vcpu->stat.invlpg; |
6017 | |
6018 | /* |
6019 | * Mappings not reachable via the current cr3 or the prev_roots will be |
6020 | * synced when switching to that cr3, so nothing needs to be done here |
6021 | * for them. |
6022 | */ |
6023 | } |
6024 | |
6025 | void kvm_configure_mmu(bool enable_tdp, int tdp_forced_root_level, |
6026 | int tdp_max_root_level, int tdp_huge_page_level) |
6027 | { |
6028 | tdp_enabled = enable_tdp; |
6029 | tdp_root_level = tdp_forced_root_level; |
6030 | max_tdp_level = tdp_max_root_level; |
6031 | |
6032 | #ifdef CONFIG_X86_64 |
6033 | tdp_mmu_enabled = tdp_mmu_allowed && tdp_enabled; |
6034 | #endif |
6035 | /* |
6036 | * max_huge_page_level reflects KVM's MMU capabilities irrespective |
6037 | * of kernel support, e.g. KVM may be capable of using 1GB pages when |
6038 | * the kernel is not. But, KVM never creates a page size greater than |
6039 | * what is used by the kernel for any given HVA, i.e. the kernel's |
6040 | * capabilities are ultimately consulted by kvm_mmu_hugepage_adjust(). |
6041 | */ |
6042 | if (tdp_enabled) |
6043 | max_huge_page_level = tdp_huge_page_level; |
6044 | else if (boot_cpu_has(X86_FEATURE_GBPAGES)) |
6045 | max_huge_page_level = PG_LEVEL_1G; |
6046 | else |
6047 | max_huge_page_level = PG_LEVEL_2M; |
6048 | } |
6049 | EXPORT_SYMBOL_GPL(kvm_configure_mmu); |
6050 | |
6051 | /* The return value indicates if tlb flush on all vcpus is needed. */ |
6052 | typedef bool (*slot_rmaps_handler) (struct kvm *kvm, |
6053 | struct kvm_rmap_head *rmap_head, |
6054 | const struct kvm_memory_slot *slot); |
6055 | |
6056 | static __always_inline bool __walk_slot_rmaps(struct kvm *kvm, |
6057 | const struct kvm_memory_slot *slot, |
6058 | slot_rmaps_handler fn, |
6059 | int start_level, int end_level, |
6060 | gfn_t start_gfn, gfn_t end_gfn, |
6061 | bool flush_on_yield, bool flush) |
6062 | { |
6063 | struct slot_rmap_walk_iterator iterator; |
6064 | |
6065 | lockdep_assert_held_write(&kvm->mmu_lock); |
6066 | |
6067 | for_each_slot_rmap_range(slot, start_level, end_level, start_gfn, |
6068 | end_gfn, &iterator) { |
6069 | if (iterator.rmap) |
6070 | flush |= fn(kvm, iterator.rmap, slot); |
6071 | |
6072 | if (need_resched() || rwlock_needbreak(lock: &kvm->mmu_lock)) { |
6073 | if (flush && flush_on_yield) { |
6074 | kvm_flush_remote_tlbs_range(kvm, gfn: start_gfn, |
6075 | nr_pages: iterator.gfn - start_gfn + 1); |
6076 | flush = false; |
6077 | } |
6078 | cond_resched_rwlock_write(&kvm->mmu_lock); |
6079 | } |
6080 | } |
6081 | |
6082 | return flush; |
6083 | } |
6084 | |
6085 | static __always_inline bool walk_slot_rmaps(struct kvm *kvm, |
6086 | const struct kvm_memory_slot *slot, |
6087 | slot_rmaps_handler fn, |
6088 | int start_level, int end_level, |
6089 | bool flush_on_yield) |
6090 | { |
6091 | return __walk_slot_rmaps(kvm, slot, fn, start_level, end_level, |
6092 | start_gfn: slot->base_gfn, end_gfn: slot->base_gfn + slot->npages - 1, |
6093 | flush_on_yield, flush: false); |
6094 | } |
6095 | |
6096 | static __always_inline bool walk_slot_rmaps_4k(struct kvm *kvm, |
6097 | const struct kvm_memory_slot *slot, |
6098 | slot_rmaps_handler fn, |
6099 | bool flush_on_yield) |
6100 | { |
6101 | return walk_slot_rmaps(kvm, slot, fn, start_level: PG_LEVEL_4K, end_level: PG_LEVEL_4K, flush_on_yield); |
6102 | } |
6103 | |
6104 | static void free_mmu_pages(struct kvm_mmu *mmu) |
6105 | { |
6106 | if (!tdp_enabled && mmu->pae_root) |
6107 | set_memory_encrypted(addr: (unsigned long)mmu->pae_root, numpages: 1); |
6108 | free_page((unsigned long)mmu->pae_root); |
6109 | free_page((unsigned long)mmu->pml4_root); |
6110 | free_page((unsigned long)mmu->pml5_root); |
6111 | } |
6112 | |
6113 | static int __kvm_mmu_create(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu) |
6114 | { |
6115 | struct page *page; |
6116 | int i; |
6117 | |
6118 | mmu->root.hpa = INVALID_PAGE; |
6119 | mmu->root.pgd = 0; |
6120 | for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) |
6121 | mmu->prev_roots[i] = KVM_MMU_ROOT_INFO_INVALID; |
6122 | |
6123 | /* vcpu->arch.guest_mmu isn't used when !tdp_enabled. */ |
6124 | if (!tdp_enabled && mmu == &vcpu->arch.guest_mmu) |
6125 | return 0; |
6126 | |
6127 | /* |
6128 | * When using PAE paging, the four PDPTEs are treated as 'root' pages, |
6129 | * while the PDP table is a per-vCPU construct that's allocated at MMU |
6130 | * creation. When emulating 32-bit mode, cr3 is only 32 bits even on |
6131 | * x86_64. Therefore we need to allocate the PDP table in the first |
6132 | * 4GB of memory, which happens to fit the DMA32 zone. TDP paging |
6133 | * generally doesn't use PAE paging and can skip allocating the PDP |
6134 | * table. The main exception, handled here, is SVM's 32-bit NPT. The |
6135 | * other exception is for shadowing L1's 32-bit or PAE NPT on 64-bit |
6136 | * KVM; that horror is handled on-demand by mmu_alloc_special_roots(). |
6137 | */ |
6138 | if (tdp_enabled && kvm_mmu_get_tdp_level(vcpu) > PT32E_ROOT_LEVEL) |
6139 | return 0; |
6140 | |
6141 | page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_DMA32); |
6142 | if (!page) |
6143 | return -ENOMEM; |
6144 | |
6145 | mmu->pae_root = page_address(page); |
6146 | |
6147 | /* |
6148 | * CR3 is only 32 bits when PAE paging is used, thus it's impossible to |
6149 | * get the CPU to treat the PDPTEs as encrypted. Decrypt the page so |
6150 | * that KVM's writes and the CPU's reads get along. Note, this is |
6151 | * only necessary when using shadow paging, as 64-bit NPT can get at |
6152 | * the C-bit even when shadowing 32-bit NPT, and SME isn't supported |
6153 | * by 32-bit kernels (when KVM itself uses 32-bit NPT). |
6154 | */ |
6155 | if (!tdp_enabled) |
6156 | set_memory_decrypted(addr: (unsigned long)mmu->pae_root, numpages: 1); |
6157 | else |
6158 | WARN_ON_ONCE(shadow_me_value); |
6159 | |
6160 | for (i = 0; i < 4; ++i) |
6161 | mmu->pae_root[i] = INVALID_PAE_ROOT; |
6162 | |
6163 | return 0; |
6164 | } |
6165 | |
6166 | int kvm_mmu_create(struct kvm_vcpu *vcpu) |
6167 | { |
6168 | int ret; |
6169 | |
6170 | vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache; |
6171 | vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO; |
6172 | |
6173 | vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache; |
6174 | vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO; |
6175 | |
6176 | vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO; |
6177 | |
6178 | vcpu->arch.mmu = &vcpu->arch.root_mmu; |
6179 | vcpu->arch.walk_mmu = &vcpu->arch.root_mmu; |
6180 | |
6181 | ret = __kvm_mmu_create(vcpu, mmu: &vcpu->arch.guest_mmu); |
6182 | if (ret) |
6183 | return ret; |
6184 | |
6185 | ret = __kvm_mmu_create(vcpu, mmu: &vcpu->arch.root_mmu); |
6186 | if (ret) |
6187 | goto fail_allocate_root; |
6188 | |
6189 | return ret; |
6190 | fail_allocate_root: |
6191 | free_mmu_pages(mmu: &vcpu->arch.guest_mmu); |
6192 | return ret; |
6193 | } |
6194 | |
6195 | #define BATCH_ZAP_PAGES 10 |
6196 | static void kvm_zap_obsolete_pages(struct kvm *kvm) |
6197 | { |
6198 | struct kvm_mmu_page *sp, *node; |
6199 | int nr_zapped, batch = 0; |
6200 | bool unstable; |
6201 | |
6202 | restart: |
6203 | list_for_each_entry_safe_reverse(sp, node, |
6204 | &kvm->arch.active_mmu_pages, link) { |
6205 | /* |
6206 | * No obsolete valid page exists before a newly created page |
6207 | * since active_mmu_pages is a FIFO list. |
6208 | */ |
6209 | if (!is_obsolete_sp(kvm, sp)) |
6210 | break; |
6211 | |
6212 | /* |
6213 | * Invalid pages should never land back on the list of active |
6214 | * pages. Skip the bogus page, otherwise we'll get stuck in an |
6215 | * infinite loop if the page gets put back on the list (again). |
6216 | */ |
6217 | if (WARN_ON_ONCE(sp->role.invalid)) |
6218 | continue; |
6219 | |
6220 | /* |
6221 | * No need to flush the TLB since we're only zapping shadow |
6222 | * pages with an obsolete generation number and all vCPUS have |
6223 | * loaded a new root, i.e. the shadow pages being zapped cannot |
6224 | * be in active use by the guest. |
6225 | */ |
6226 | if (batch >= BATCH_ZAP_PAGES && |
6227 | cond_resched_rwlock_write(&kvm->mmu_lock)) { |
6228 | batch = 0; |
6229 | goto restart; |
6230 | } |
6231 | |
6232 | unstable = __kvm_mmu_prepare_zap_page(kvm, sp, |
6233 | invalid_list: &kvm->arch.zapped_obsolete_pages, nr_zapped: &nr_zapped); |
6234 | batch += nr_zapped; |
6235 | |
6236 | if (unstable) |
6237 | goto restart; |
6238 | } |
6239 | |
6240 | /* |
6241 | * Kick all vCPUs (via remote TLB flush) before freeing the page tables |
6242 | * to ensure KVM is not in the middle of a lockless shadow page table |
6243 | * walk, which may reference the pages. The remote TLB flush itself is |
6244 | * not required and is simply a convenient way to kick vCPUs as needed. |
6245 | * KVM performs a local TLB flush when allocating a new root (see |
6246 | * kvm_mmu_load()), and the reload in the caller ensure no vCPUs are |
6247 | * running with an obsolete MMU. |
6248 | */ |
6249 | kvm_mmu_commit_zap_page(kvm, invalid_list: &kvm->arch.zapped_obsolete_pages); |
6250 | } |
6251 | |
6252 | /* |
6253 | * Fast invalidate all shadow pages and use lock-break technique |
6254 | * to zap obsolete pages. |
6255 | * |
6256 | * It's required when memslot is being deleted or VM is being |
6257 | * destroyed, in these cases, we should ensure that KVM MMU does |
6258 | * not use any resource of the being-deleted slot or all slots |
6259 | * after calling the function. |
6260 | */ |
6261 | static void kvm_mmu_zap_all_fast(struct kvm *kvm) |
6262 | { |
6263 | lockdep_assert_held(&kvm->slots_lock); |
6264 | |
6265 | write_lock(&kvm->mmu_lock); |
6266 | trace_kvm_mmu_zap_all_fast(kvm); |
6267 | |
6268 | /* |
6269 | * Toggle mmu_valid_gen between '0' and '1'. Because slots_lock is |
6270 | * held for the entire duration of zapping obsolete pages, it's |
6271 | * impossible for there to be multiple invalid generations associated |
6272 | * with *valid* shadow pages at any given time, i.e. there is exactly |
6273 | * one valid generation and (at most) one invalid generation. |
6274 | */ |
6275 | kvm->arch.mmu_valid_gen = kvm->arch.mmu_valid_gen ? 0 : 1; |
6276 | |
6277 | /* |
6278 | * In order to ensure all vCPUs drop their soon-to-be invalid roots, |
6279 | * invalidating TDP MMU roots must be done while holding mmu_lock for |
6280 | * write and in the same critical section as making the reload request, |
6281 | * e.g. before kvm_zap_obsolete_pages() could drop mmu_lock and yield. |
6282 | */ |
6283 | if (tdp_mmu_enabled) |
6284 | kvm_tdp_mmu_invalidate_all_roots(kvm); |
6285 | |
6286 | /* |
6287 | * Notify all vcpus to reload its shadow page table and flush TLB. |
6288 | * Then all vcpus will switch to new shadow page table with the new |
6289 | * mmu_valid_gen. |
6290 | * |
6291 | * Note: we need to do this under the protection of mmu_lock, |
6292 | * otherwise, vcpu would purge shadow page but miss tlb flush. |
6293 | */ |
6294 | kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_FREE_OBSOLETE_ROOTS); |
6295 | |
6296 | kvm_zap_obsolete_pages(kvm); |
6297 | |
6298 | write_unlock(&kvm->mmu_lock); |
6299 | |
6300 | /* |
6301 | * Zap the invalidated TDP MMU roots, all SPTEs must be dropped before |
6302 | * returning to the caller, e.g. if the zap is in response to a memslot |
6303 | * deletion, mmu_notifier callbacks will be unable to reach the SPTEs |
6304 | * associated with the deleted memslot once the update completes, and |
6305 | * Deferring the zap until the final reference to the root is put would |
6306 | * lead to use-after-free. |
6307 | */ |
6308 | if (tdp_mmu_enabled) |
6309 | kvm_tdp_mmu_zap_invalidated_roots(kvm); |
6310 | } |
6311 | |
6312 | static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm) |
6313 | { |
6314 | return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages)); |
6315 | } |
6316 | |
6317 | void kvm_mmu_init_vm(struct kvm *kvm) |
6318 | { |
6319 | INIT_LIST_HEAD(list: &kvm->arch.active_mmu_pages); |
6320 | INIT_LIST_HEAD(list: &kvm->arch.zapped_obsolete_pages); |
6321 | INIT_LIST_HEAD(list: &kvm->arch.possible_nx_huge_pages); |
6322 | spin_lock_init(&kvm->arch.mmu_unsync_pages_lock); |
6323 | |
6324 | if (tdp_mmu_enabled) |
6325 | kvm_mmu_init_tdp_mmu(kvm); |
6326 | |
6327 | kvm->arch.split_page_header_cache.kmem_cache = mmu_page_header_cache; |
6328 | kvm->arch.split_page_header_cache.gfp_zero = __GFP_ZERO; |
6329 | |
6330 | kvm->arch.split_shadow_page_cache.gfp_zero = __GFP_ZERO; |
6331 | |
6332 | kvm->arch.split_desc_cache.kmem_cache = pte_list_desc_cache; |
6333 | kvm->arch.split_desc_cache.gfp_zero = __GFP_ZERO; |
6334 | } |
6335 | |
6336 | static void mmu_free_vm_memory_caches(struct kvm *kvm) |
6337 | { |
6338 | kvm_mmu_free_memory_cache(mc: &kvm->arch.split_desc_cache); |
6339 | kvm_mmu_free_memory_cache(mc: &kvm->arch.split_page_header_cache); |
6340 | kvm_mmu_free_memory_cache(mc: &kvm->arch.split_shadow_page_cache); |
6341 | } |
6342 | |
6343 | void kvm_mmu_uninit_vm(struct kvm *kvm) |
6344 | { |
6345 | if (tdp_mmu_enabled) |
6346 | kvm_mmu_uninit_tdp_mmu(kvm); |
6347 | |
6348 | mmu_free_vm_memory_caches(kvm); |
6349 | } |
6350 | |
6351 | static bool kvm_rmap_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) |
6352 | { |
6353 | const struct kvm_memory_slot *memslot; |
6354 | struct kvm_memslots *slots; |
6355 | struct kvm_memslot_iter iter; |
6356 | bool flush = false; |
6357 | gfn_t start, end; |
6358 | int i; |
6359 | |
6360 | if (!kvm_memslots_have_rmaps(kvm)) |
6361 | return flush; |
6362 | |
6363 | for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) { |
6364 | slots = __kvm_memslots(kvm, as_id: i); |
6365 | |
6366 | kvm_for_each_memslot_in_gfn_range(&iter, slots, gfn_start, gfn_end) { |
6367 | memslot = iter.slot; |
6368 | start = max(gfn_start, memslot->base_gfn); |
6369 | end = min(gfn_end, memslot->base_gfn + memslot->npages); |
6370 | if (WARN_ON_ONCE(start >= end)) |
6371 | continue; |
6372 | |
6373 | flush = __walk_slot_rmaps(kvm, slot: memslot, fn: __kvm_zap_rmap, |
6374 | start_level: PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL, |
6375 | start_gfn: start, end_gfn: end - 1, flush_on_yield: true, flush); |
6376 | } |
6377 | } |
6378 | |
6379 | return flush; |
6380 | } |
6381 | |
6382 | /* |
6383 | * Invalidate (zap) SPTEs that cover GFNs from gfn_start and up to gfn_end |
6384 | * (not including it) |
6385 | */ |
6386 | void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) |
6387 | { |
6388 | bool flush; |
6389 | |
6390 | if (WARN_ON_ONCE(gfn_end <= gfn_start)) |
6391 | return; |
6392 | |
6393 | write_lock(&kvm->mmu_lock); |
6394 | |
6395 | kvm_mmu_invalidate_begin(kvm); |
6396 | |
6397 | kvm_mmu_invalidate_range_add(kvm, start: gfn_start, end: gfn_end); |
6398 | |
6399 | flush = kvm_rmap_zap_gfn_range(kvm, gfn_start, gfn_end); |
6400 | |
6401 | if (tdp_mmu_enabled) |
6402 | flush = kvm_tdp_mmu_zap_leafs(kvm, start: gfn_start, end: gfn_end, flush); |
6403 | |
6404 | if (flush) |
6405 | kvm_flush_remote_tlbs_range(kvm, gfn: gfn_start, nr_pages: gfn_end - gfn_start); |
6406 | |
6407 | kvm_mmu_invalidate_end(kvm); |
6408 | |
6409 | write_unlock(&kvm->mmu_lock); |
6410 | } |
6411 | |
6412 | static bool slot_rmap_write_protect(struct kvm *kvm, |
6413 | struct kvm_rmap_head *rmap_head, |
6414 | const struct kvm_memory_slot *slot) |
6415 | { |
6416 | return rmap_write_protect(rmap_head, pt_protect: false); |
6417 | } |
6418 | |
6419 | void kvm_mmu_slot_remove_write_access(struct kvm *kvm, |
6420 | const struct kvm_memory_slot *memslot, |
6421 | int start_level) |
6422 | { |
6423 | if (kvm_memslots_have_rmaps(kvm)) { |
6424 | write_lock(&kvm->mmu_lock); |
6425 | walk_slot_rmaps(kvm, slot: memslot, fn: slot_rmap_write_protect, |
6426 | start_level, KVM_MAX_HUGEPAGE_LEVEL, flush_on_yield: false); |
6427 | write_unlock(&kvm->mmu_lock); |
6428 | } |
6429 | |
6430 | if (tdp_mmu_enabled) { |
6431 | read_lock(&kvm->mmu_lock); |
6432 | kvm_tdp_mmu_wrprot_slot(kvm, slot: memslot, min_level: start_level); |
6433 | read_unlock(&kvm->mmu_lock); |
6434 | } |
6435 | } |
6436 | |
6437 | static inline bool need_topup(struct kvm_mmu_memory_cache *cache, int min) |
6438 | { |
6439 | return kvm_mmu_memory_cache_nr_free_objects(mc: cache) < min; |
6440 | } |
6441 | |
6442 | static bool need_topup_split_caches_or_resched(struct kvm *kvm) |
6443 | { |
6444 | if (need_resched() || rwlock_needbreak(lock: &kvm->mmu_lock)) |
6445 | return true; |
6446 | |
6447 | /* |
6448 | * In the worst case, SPLIT_DESC_CACHE_MIN_NR_OBJECTS descriptors are needed |
6449 | * to split a single huge page. Calculating how many are actually needed |
6450 | * is possible but not worth the complexity. |
6451 | */ |
6452 | return need_topup(cache: &kvm->arch.split_desc_cache, SPLIT_DESC_CACHE_MIN_NR_OBJECTS) || |
6453 | need_topup(cache: &kvm->arch.split_page_header_cache, min: 1) || |
6454 | need_topup(cache: &kvm->arch.split_shadow_page_cache, min: 1); |
6455 | } |
6456 | |
6457 | static int topup_split_caches(struct kvm *kvm) |
6458 | { |
6459 | /* |
6460 | * Allocating rmap list entries when splitting huge pages for nested |
6461 | * MMUs is uncommon as KVM needs to use a list if and only if there is |
6462 | * more than one rmap entry for a gfn, i.e. requires an L1 gfn to be |
6463 | * aliased by multiple L2 gfns and/or from multiple nested roots with |
6464 | * different roles. Aliasing gfns when using TDP is atypical for VMMs; |
6465 | * a few gfns are often aliased during boot, e.g. when remapping BIOS, |
6466 | * but aliasing rarely occurs post-boot or for many gfns. If there is |
6467 | * only one rmap entry, rmap->val points directly at that one entry and |
6468 | * doesn't need to allocate a list. Buffer the cache by the default |
6469 | * capacity so that KVM doesn't have to drop mmu_lock to topup if KVM |
6470 | * encounters an aliased gfn or two. |
6471 | */ |
6472 | const int capacity = SPLIT_DESC_CACHE_MIN_NR_OBJECTS + |
6473 | KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE; |
6474 | int r; |
6475 | |
6476 | lockdep_assert_held(&kvm->slots_lock); |
6477 | |
6478 | r = __kvm_mmu_topup_memory_cache(mc: &kvm->arch.split_desc_cache, capacity, |
6479 | SPLIT_DESC_CACHE_MIN_NR_OBJECTS); |
6480 | if (r) |
6481 | return r; |
6482 | |
6483 | r = kvm_mmu_topup_memory_cache(mc: &kvm->arch.split_page_header_cache, min: 1); |
6484 | if (r) |
6485 | return r; |
6486 | |
6487 | return kvm_mmu_topup_memory_cache(mc: &kvm->arch.split_shadow_page_cache, min: 1); |
6488 | } |
6489 | |
6490 | static struct kvm_mmu_page *shadow_mmu_get_sp_for_split(struct kvm *kvm, u64 *huge_sptep) |
6491 | { |
6492 | struct kvm_mmu_page *huge_sp = sptep_to_sp(sptep: huge_sptep); |
6493 | struct shadow_page_caches caches = {}; |
6494 | union kvm_mmu_page_role role; |
6495 | unsigned int access; |
6496 | gfn_t gfn; |
6497 | |
6498 | gfn = kvm_mmu_page_get_gfn(sp: huge_sp, index: spte_index(sptep: huge_sptep)); |
6499 | access = kvm_mmu_page_get_access(sp: huge_sp, index: spte_index(sptep: huge_sptep)); |
6500 | |
6501 | /* |
6502 | * Note, huge page splitting always uses direct shadow pages, regardless |
6503 | * of whether the huge page itself is mapped by a direct or indirect |
6504 | * shadow page, since the huge page region itself is being directly |
6505 | * mapped with smaller pages. |
6506 | */ |
6507 | role = kvm_mmu_child_role(sptep: huge_sptep, /*direct=*/true, access); |
6508 | |
6509 | /* Direct SPs do not require a shadowed_info_cache. */ |
6510 | caches.page_header_cache = &kvm->arch.split_page_header_cache; |
6511 | caches.shadow_page_cache = &kvm->arch.split_shadow_page_cache; |
6512 | |
6513 | /* Safe to pass NULL for vCPU since requesting a direct SP. */ |
6514 | return __kvm_mmu_get_shadow_page(kvm, NULL, caches: &caches, gfn, role); |
6515 | } |
6516 | |
6517 | static void shadow_mmu_split_huge_page(struct kvm *kvm, |
6518 | const struct kvm_memory_slot *slot, |
6519 | u64 *huge_sptep) |
6520 | |
6521 | { |
6522 | struct kvm_mmu_memory_cache *cache = &kvm->arch.split_desc_cache; |
6523 | u64 huge_spte = READ_ONCE(*huge_sptep); |
6524 | struct kvm_mmu_page *sp; |
6525 | bool flush = false; |
6526 | u64 *sptep, spte; |
6527 | gfn_t gfn; |
6528 | int index; |
6529 | |
6530 | sp = shadow_mmu_get_sp_for_split(kvm, huge_sptep); |
6531 | |
6532 | for (index = 0; index < SPTE_ENT_PER_PAGE; index++) { |
6533 | sptep = &sp->spt[index]; |
6534 | gfn = kvm_mmu_page_get_gfn(sp, index); |
6535 | |
6536 | /* |
6537 | * The SP may already have populated SPTEs, e.g. if this huge |
6538 | * page is aliased by multiple sptes with the same access |
6539 | * permissions. These entries are guaranteed to map the same |
6540 | * gfn-to-pfn translation since the SP is direct, so no need to |
6541 | * modify them. |
6542 | * |
6543 | * However, if a given SPTE points to a lower level page table, |
6544 | * that lower level page table may only be partially populated. |
6545 | * Installing such SPTEs would effectively unmap a potion of the |
6546 | * huge page. Unmapping guest memory always requires a TLB flush |
6547 | * since a subsequent operation on the unmapped regions would |
6548 | * fail to detect the need to flush. |
6549 | */ |
6550 | if (is_shadow_present_pte(pte: *sptep)) { |
6551 | flush |= !is_last_spte(pte: *sptep, level: sp->role.level); |
6552 | continue; |
6553 | } |
6554 | |
6555 | spte = make_huge_page_split_spte(kvm, huge_spte, role: sp->role, index); |
6556 | mmu_spte_set(sptep, new_spte: spte); |
6557 | __rmap_add(kvm, cache, slot, spte: sptep, gfn, access: sp->role.access); |
6558 | } |
6559 | |
6560 | __link_shadow_page(kvm, cache, sptep: huge_sptep, sp, flush); |
6561 | } |
6562 | |
6563 | static int shadow_mmu_try_split_huge_page(struct kvm *kvm, |
6564 | const struct kvm_memory_slot *slot, |
6565 | u64 *huge_sptep) |
6566 | { |
6567 | struct kvm_mmu_page *huge_sp = sptep_to_sp(sptep: huge_sptep); |
6568 | int level, r = 0; |
6569 | gfn_t gfn; |
6570 | u64 spte; |
6571 | |
6572 | /* Grab information for the tracepoint before dropping the MMU lock. */ |
6573 | gfn = kvm_mmu_page_get_gfn(sp: huge_sp, index: spte_index(sptep: huge_sptep)); |
6574 | level = huge_sp->role.level; |
6575 | spte = *huge_sptep; |
6576 | |
6577 | if (kvm_mmu_available_pages(kvm) <= KVM_MIN_FREE_MMU_PAGES) { |
6578 | r = -ENOSPC; |
6579 | goto out; |
6580 | } |
6581 | |
6582 | if (need_topup_split_caches_or_resched(kvm)) { |
6583 | write_unlock(&kvm->mmu_lock); |
6584 | cond_resched(); |
6585 | /* |
6586 | * If the topup succeeds, return -EAGAIN to indicate that the |
6587 | * rmap iterator should be restarted because the MMU lock was |
6588 | * dropped. |
6589 | */ |
6590 | r = topup_split_caches(kvm) ?: -EAGAIN; |
6591 | write_lock(&kvm->mmu_lock); |
6592 | goto out; |
6593 | } |
6594 | |
6595 | shadow_mmu_split_huge_page(kvm, slot, huge_sptep); |
6596 | |
6597 | out: |
6598 | trace_kvm_mmu_split_huge_page(gfn, spte, level, errno: r); |
6599 | return r; |
6600 | } |
6601 | |
6602 | static bool shadow_mmu_try_split_huge_pages(struct kvm *kvm, |
6603 | struct kvm_rmap_head *rmap_head, |
6604 | const struct kvm_memory_slot *slot) |
6605 | { |
6606 | struct rmap_iterator iter; |
6607 | struct kvm_mmu_page *sp; |
6608 | u64 *huge_sptep; |
6609 | int r; |
6610 | |
6611 | restart: |
6612 | for_each_rmap_spte(rmap_head, &iter, huge_sptep) { |
6613 | sp = sptep_to_sp(sptep: huge_sptep); |
6614 | |
6615 | /* TDP MMU is enabled, so rmap only contains nested MMU SPs. */ |
6616 | if (WARN_ON_ONCE(!sp->role.guest_mode)) |
6617 | continue; |
6618 | |
6619 | /* The rmaps should never contain non-leaf SPTEs. */ |
6620 | if (WARN_ON_ONCE(!is_large_pte(*huge_sptep))) |
6621 | continue; |
6622 | |
6623 | /* SPs with level >PG_LEVEL_4K should never by unsync. */ |
6624 | if (WARN_ON_ONCE(sp->unsync)) |
6625 | continue; |
6626 | |
6627 | /* Don't bother splitting huge pages on invalid SPs. */ |
6628 | if (sp->role.invalid) |
6629 | continue; |
6630 | |
6631 | r = shadow_mmu_try_split_huge_page(kvm, slot, huge_sptep); |
6632 | |
6633 | /* |
6634 | * The split succeeded or needs to be retried because the MMU |
6635 | * lock was dropped. Either way, restart the iterator to get it |
6636 | * back into a consistent state. |
6637 | */ |
6638 | if (!r || r == -EAGAIN) |
6639 | goto restart; |
6640 | |
6641 | /* The split failed and shouldn't be retried (e.g. -ENOMEM). */ |
6642 | break; |
6643 | } |
6644 | |
6645 | return false; |
6646 | } |
6647 | |
6648 | static void kvm_shadow_mmu_try_split_huge_pages(struct kvm *kvm, |
6649 | const struct kvm_memory_slot *slot, |
6650 | gfn_t start, gfn_t end, |
6651 | int target_level) |
6652 | { |
6653 | int level; |
6654 | |
6655 | /* |
6656 | * Split huge pages starting with KVM_MAX_HUGEPAGE_LEVEL and working |
6657 | * down to the target level. This ensures pages are recursively split |
6658 | * all the way to the target level. There's no need to split pages |
6659 | * already at the target level. |
6660 | */ |
6661 | for (level = KVM_MAX_HUGEPAGE_LEVEL; level > target_level; level--) |
6662 | __walk_slot_rmaps(kvm, slot, fn: shadow_mmu_try_split_huge_pages, |
6663 | start_level: level, end_level: level, start_gfn: start, end_gfn: end - 1, flush_on_yield: true, flush: false); |
6664 | } |
6665 | |
6666 | /* Must be called with the mmu_lock held in write-mode. */ |
6667 | void kvm_mmu_try_split_huge_pages(struct kvm *kvm, |
6668 | const struct kvm_memory_slot *memslot, |
6669 | u64 start, u64 end, |
6670 | int target_level) |
6671 | { |
6672 | if (!tdp_mmu_enabled) |
6673 | return; |
6674 | |
6675 | if (kvm_memslots_have_rmaps(kvm)) |
6676 | kvm_shadow_mmu_try_split_huge_pages(kvm, slot: memslot, start, end, target_level); |
6677 | |
6678 | kvm_tdp_mmu_try_split_huge_pages(kvm, slot: memslot, start, end, target_level, shared: false); |
6679 | |
6680 | /* |
6681 | * A TLB flush is unnecessary at this point for the same reasons as in |
6682 | * kvm_mmu_slot_try_split_huge_pages(). |
6683 | */ |
6684 | } |
6685 | |
6686 | void kvm_mmu_slot_try_split_huge_pages(struct kvm *kvm, |
6687 | const struct kvm_memory_slot *memslot, |
6688 | int target_level) |
6689 | { |
6690 | u64 start = memslot->base_gfn; |
6691 | u64 end = start + memslot->npages; |
6692 | |
6693 | if (!tdp_mmu_enabled) |
6694 | return; |
6695 | |
6696 | if (kvm_memslots_have_rmaps(kvm)) { |
6697 | write_lock(&kvm->mmu_lock); |
6698 | kvm_shadow_mmu_try_split_huge_pages(kvm, slot: memslot, start, end, target_level); |
6699 | write_unlock(&kvm->mmu_lock); |
6700 | } |
6701 | |
6702 | read_lock(&kvm->mmu_lock); |
6703 | kvm_tdp_mmu_try_split_huge_pages(kvm, slot: memslot, start, end, target_level, shared: true); |
6704 | read_unlock(&kvm->mmu_lock); |
6705 | |
6706 | /* |
6707 | * No TLB flush is necessary here. KVM will flush TLBs after |
6708 | * write-protecting and/or clearing dirty on the newly split SPTEs to |
6709 | * ensure that guest writes are reflected in the dirty log before the |
6710 | * ioctl to enable dirty logging on this memslot completes. Since the |
6711 | * split SPTEs retain the write and dirty bits of the huge SPTE, it is |
6712 | * safe for KVM to decide if a TLB flush is necessary based on the split |
6713 | * SPTEs. |
6714 | */ |
6715 | } |
6716 | |
6717 | static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm, |
6718 | struct kvm_rmap_head *rmap_head, |
6719 | const struct kvm_memory_slot *slot) |
6720 | { |
6721 | u64 *sptep; |
6722 | struct rmap_iterator iter; |
6723 | int need_tlb_flush = 0; |
6724 | struct kvm_mmu_page *sp; |
6725 | |
6726 | restart: |
6727 | for_each_rmap_spte(rmap_head, &iter, sptep) { |
6728 | sp = sptep_to_sp(sptep); |
6729 | |
6730 | /* |
6731 | * We cannot do huge page mapping for indirect shadow pages, |
6732 | * which are found on the last rmap (level = 1) when not using |
6733 | * tdp; such shadow pages are synced with the page table in |
6734 | * the guest, and the guest page table is using 4K page size |
6735 | * mapping if the indirect sp has level = 1. |
6736 | */ |
6737 | if (sp->role.direct && |
6738 | sp->role.level < kvm_mmu_max_mapping_level(kvm, slot, gfn: sp->gfn, |
6739 | max_level: PG_LEVEL_NUM)) { |
6740 | kvm_zap_one_rmap_spte(kvm, rmap_head, sptep); |
6741 | |
6742 | if (kvm_available_flush_remote_tlbs_range()) |
6743 | kvm_flush_remote_tlbs_sptep(kvm, sptep); |
6744 | else |
6745 | need_tlb_flush = 1; |
6746 | |
6747 | goto restart; |
6748 | } |
6749 | } |
6750 | |
6751 | return need_tlb_flush; |
6752 | } |
6753 | |
6754 | static void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm, |
6755 | const struct kvm_memory_slot *slot) |
6756 | { |
6757 | /* |
6758 | * Note, use KVM_MAX_HUGEPAGE_LEVEL - 1 since there's no need to zap |
6759 | * pages that are already mapped at the maximum hugepage level. |
6760 | */ |
6761 | if (walk_slot_rmaps(kvm, slot, fn: kvm_mmu_zap_collapsible_spte, |
6762 | start_level: PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL - 1, flush_on_yield: true)) |
6763 | kvm_flush_remote_tlbs_memslot(kvm, memslot: slot); |
6764 | } |
6765 | |
6766 | void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm, |
6767 | const struct kvm_memory_slot *slot) |
6768 | { |
6769 | if (kvm_memslots_have_rmaps(kvm)) { |
6770 | write_lock(&kvm->mmu_lock); |
6771 | kvm_rmap_zap_collapsible_sptes(kvm, slot); |
6772 | write_unlock(&kvm->mmu_lock); |
6773 | } |
6774 | |
6775 | if (tdp_mmu_enabled) { |
6776 | read_lock(&kvm->mmu_lock); |
6777 | kvm_tdp_mmu_zap_collapsible_sptes(kvm, slot); |
6778 | read_unlock(&kvm->mmu_lock); |
6779 | } |
6780 | } |
6781 | |
6782 | void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm, |
6783 | const struct kvm_memory_slot *memslot) |
6784 | { |
6785 | if (kvm_memslots_have_rmaps(kvm)) { |
6786 | write_lock(&kvm->mmu_lock); |
6787 | /* |
6788 | * Clear dirty bits only on 4k SPTEs since the legacy MMU only |
6789 | * support dirty logging at a 4k granularity. |
6790 | */ |
6791 | walk_slot_rmaps_4k(kvm, slot: memslot, fn: __rmap_clear_dirty, flush_on_yield: false); |
6792 | write_unlock(&kvm->mmu_lock); |
6793 | } |
6794 | |
6795 | if (tdp_mmu_enabled) { |
6796 | read_lock(&kvm->mmu_lock); |
6797 | kvm_tdp_mmu_clear_dirty_slot(kvm, slot: memslot); |
6798 | read_unlock(&kvm->mmu_lock); |
6799 | } |
6800 | |
6801 | /* |
6802 | * The caller will flush the TLBs after this function returns. |
6803 | * |
6804 | * It's also safe to flush TLBs out of mmu lock here as currently this |
6805 | * function is only used for dirty logging, in which case flushing TLB |
6806 | * out of mmu lock also guarantees no dirty pages will be lost in |
6807 | * dirty_bitmap. |
6808 | */ |
6809 | } |
6810 | |
6811 | static void kvm_mmu_zap_all(struct kvm *kvm) |
6812 | { |
6813 | struct kvm_mmu_page *sp, *node; |
6814 | LIST_HEAD(invalid_list); |
6815 | int ign; |
6816 | |
6817 | write_lock(&kvm->mmu_lock); |
6818 | restart: |
6819 | list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link) { |
6820 | if (WARN_ON_ONCE(sp->role.invalid)) |
6821 | continue; |
6822 | if (__kvm_mmu_prepare_zap_page(kvm, sp, invalid_list: &invalid_list, nr_zapped: &ign)) |
6823 | goto restart; |
6824 | if (cond_resched_rwlock_write(&kvm->mmu_lock)) |
6825 | goto restart; |
6826 | } |
6827 | |
6828 | kvm_mmu_commit_zap_page(kvm, invalid_list: &invalid_list); |
6829 | |
6830 | if (tdp_mmu_enabled) |
6831 | kvm_tdp_mmu_zap_all(kvm); |
6832 | |
6833 | write_unlock(&kvm->mmu_lock); |
6834 | } |
6835 | |
6836 | void kvm_arch_flush_shadow_all(struct kvm *kvm) |
6837 | { |
6838 | kvm_mmu_zap_all(kvm); |
6839 | } |
6840 | |
6841 | void kvm_arch_flush_shadow_memslot(struct kvm *kvm, |
6842 | struct kvm_memory_slot *slot) |
6843 | { |
6844 | kvm_mmu_zap_all_fast(kvm); |
6845 | } |
6846 | |
6847 | void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen) |
6848 | { |
6849 | WARN_ON_ONCE(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS); |
6850 | |
6851 | gen &= MMIO_SPTE_GEN_MASK; |
6852 | |
6853 | /* |
6854 | * Generation numbers are incremented in multiples of the number of |
6855 | * address spaces in order to provide unique generations across all |
6856 | * address spaces. Strip what is effectively the address space |
6857 | * modifier prior to checking for a wrap of the MMIO generation so |
6858 | * that a wrap in any address space is detected. |
6859 | */ |
6860 | gen &= ~((u64)kvm_arch_nr_memslot_as_ids(kvm) - 1); |
6861 | |
6862 | /* |
6863 | * The very rare case: if the MMIO generation number has wrapped, |
6864 | * zap all shadow pages. |
6865 | */ |
6866 | if (unlikely(gen == 0)) { |
6867 | kvm_debug_ratelimited("zapping shadow pages for mmio generation wraparound\n" ); |
6868 | kvm_mmu_zap_all_fast(kvm); |
6869 | } |
6870 | } |
6871 | |
6872 | static unsigned long mmu_shrink_scan(struct shrinker *shrink, |
6873 | struct shrink_control *sc) |
6874 | { |
6875 | struct kvm *kvm; |
6876 | int nr_to_scan = sc->nr_to_scan; |
6877 | unsigned long freed = 0; |
6878 | |
6879 | mutex_lock(&kvm_lock); |
6880 | |
6881 | list_for_each_entry(kvm, &vm_list, vm_list) { |
6882 | int idx; |
6883 | LIST_HEAD(invalid_list); |
6884 | |
6885 | /* |
6886 | * Never scan more than sc->nr_to_scan VM instances. |
6887 | * Will not hit this condition practically since we do not try |
6888 | * to shrink more than one VM and it is very unlikely to see |
6889 | * !n_used_mmu_pages so many times. |
6890 | */ |
6891 | if (!nr_to_scan--) |
6892 | break; |
6893 | /* |
6894 | * n_used_mmu_pages is accessed without holding kvm->mmu_lock |
6895 | * here. We may skip a VM instance errorneosly, but we do not |
6896 | * want to shrink a VM that only started to populate its MMU |
6897 | * anyway. |
6898 | */ |
6899 | if (!kvm->arch.n_used_mmu_pages && |
6900 | !kvm_has_zapped_obsolete_pages(kvm)) |
6901 | continue; |
6902 | |
6903 | idx = srcu_read_lock(ssp: &kvm->srcu); |
6904 | write_lock(&kvm->mmu_lock); |
6905 | |
6906 | if (kvm_has_zapped_obsolete_pages(kvm)) { |
6907 | kvm_mmu_commit_zap_page(kvm, |
6908 | invalid_list: &kvm->arch.zapped_obsolete_pages); |
6909 | goto unlock; |
6910 | } |
6911 | |
6912 | freed = kvm_mmu_zap_oldest_mmu_pages(kvm, nr_to_zap: sc->nr_to_scan); |
6913 | |
6914 | unlock: |
6915 | write_unlock(&kvm->mmu_lock); |
6916 | srcu_read_unlock(ssp: &kvm->srcu, idx); |
6917 | |
6918 | /* |
6919 | * unfair on small ones |
6920 | * per-vm shrinkers cry out |
6921 | * sadness comes quickly |
6922 | */ |
6923 | list_move_tail(list: &kvm->vm_list, head: &vm_list); |
6924 | break; |
6925 | } |
6926 | |
6927 | mutex_unlock(lock: &kvm_lock); |
6928 | return freed; |
6929 | } |
6930 | |
6931 | static unsigned long mmu_shrink_count(struct shrinker *shrink, |
6932 | struct shrink_control *sc) |
6933 | { |
6934 | return percpu_counter_read_positive(fbc: &kvm_total_used_mmu_pages); |
6935 | } |
6936 | |
6937 | static struct shrinker *mmu_shrinker; |
6938 | |
6939 | static void mmu_destroy_caches(void) |
6940 | { |
6941 | kmem_cache_destroy(s: pte_list_desc_cache); |
6942 | kmem_cache_destroy(s: mmu_page_header_cache); |
6943 | } |
6944 | |
6945 | static int get_nx_huge_pages(char *buffer, const struct kernel_param *kp) |
6946 | { |
6947 | if (nx_hugepage_mitigation_hard_disabled) |
6948 | return sysfs_emit(buf: buffer, fmt: "never\n" ); |
6949 | |
6950 | return param_get_bool(buffer, kp); |
6951 | } |
6952 | |
6953 | static bool get_nx_auto_mode(void) |
6954 | { |
6955 | /* Return true when CPU has the bug, and mitigations are ON */ |
6956 | return boot_cpu_has_bug(X86_BUG_ITLB_MULTIHIT) && !cpu_mitigations_off(); |
6957 | } |
6958 | |
6959 | static void __set_nx_huge_pages(bool val) |
6960 | { |
6961 | nx_huge_pages = itlb_multihit_kvm_mitigation = val; |
6962 | } |
6963 | |
6964 | static int set_nx_huge_pages(const char *val, const struct kernel_param *kp) |
6965 | { |
6966 | bool old_val = nx_huge_pages; |
6967 | bool new_val; |
6968 | |
6969 | if (nx_hugepage_mitigation_hard_disabled) |
6970 | return -EPERM; |
6971 | |
6972 | /* In "auto" mode deploy workaround only if CPU has the bug. */ |
6973 | if (sysfs_streq(s1: val, s2: "off" )) { |
6974 | new_val = 0; |
6975 | } else if (sysfs_streq(s1: val, s2: "force" )) { |
6976 | new_val = 1; |
6977 | } else if (sysfs_streq(s1: val, s2: "auto" )) { |
6978 | new_val = get_nx_auto_mode(); |
6979 | } else if (sysfs_streq(s1: val, s2: "never" )) { |
6980 | new_val = 0; |
6981 | |
6982 | mutex_lock(&kvm_lock); |
6983 | if (!list_empty(head: &vm_list)) { |
6984 | mutex_unlock(lock: &kvm_lock); |
6985 | return -EBUSY; |
6986 | } |
6987 | nx_hugepage_mitigation_hard_disabled = true; |
6988 | mutex_unlock(lock: &kvm_lock); |
6989 | } else if (kstrtobool(s: val, res: &new_val) < 0) { |
6990 | return -EINVAL; |
6991 | } |
6992 | |
6993 | __set_nx_huge_pages(val: new_val); |
6994 | |
6995 | if (new_val != old_val) { |
6996 | struct kvm *kvm; |
6997 | |
6998 | mutex_lock(&kvm_lock); |
6999 | |
7000 | list_for_each_entry(kvm, &vm_list, vm_list) { |
7001 | mutex_lock(&kvm->slots_lock); |
7002 | kvm_mmu_zap_all_fast(kvm); |
7003 | mutex_unlock(lock: &kvm->slots_lock); |
7004 | |
7005 | wake_up_process(tsk: kvm->arch.nx_huge_page_recovery_thread); |
7006 | } |
7007 | mutex_unlock(lock: &kvm_lock); |
7008 | } |
7009 | |
7010 | return 0; |
7011 | } |
7012 | |
7013 | /* |
7014 | * nx_huge_pages needs to be resolved to true/false when kvm.ko is loaded, as |
7015 | * its default value of -1 is technically undefined behavior for a boolean. |
7016 | * Forward the module init call to SPTE code so that it too can handle module |
7017 | * params that need to be resolved/snapshot. |
7018 | */ |
7019 | void __init kvm_mmu_x86_module_init(void) |
7020 | { |
7021 | if (nx_huge_pages == -1) |
7022 | __set_nx_huge_pages(val: get_nx_auto_mode()); |
7023 | |
7024 | /* |
7025 | * Snapshot userspace's desire to enable the TDP MMU. Whether or not the |
7026 | * TDP MMU is actually enabled is determined in kvm_configure_mmu() |
7027 | * when the vendor module is loaded. |
7028 | */ |
7029 | tdp_mmu_allowed = tdp_mmu_enabled; |
7030 | |
7031 | kvm_mmu_spte_module_init(); |
7032 | } |
7033 | |
7034 | /* |
7035 | * The bulk of the MMU initialization is deferred until the vendor module is |
7036 | * loaded as many of the masks/values may be modified by VMX or SVM, i.e. need |
7037 | * to be reset when a potentially different vendor module is loaded. |
7038 | */ |
7039 | int kvm_mmu_vendor_module_init(void) |
7040 | { |
7041 | int ret = -ENOMEM; |
7042 | |
7043 | /* |
7044 | * MMU roles use union aliasing which is, generally speaking, an |
7045 | * undefined behavior. However, we supposedly know how compilers behave |
7046 | * and the current status quo is unlikely to change. Guardians below are |
7047 | * supposed to let us know if the assumption becomes false. |
7048 | */ |
7049 | BUILD_BUG_ON(sizeof(union kvm_mmu_page_role) != sizeof(u32)); |
7050 | BUILD_BUG_ON(sizeof(union kvm_mmu_extended_role) != sizeof(u32)); |
7051 | BUILD_BUG_ON(sizeof(union kvm_cpu_role) != sizeof(u64)); |
7052 | |
7053 | kvm_mmu_reset_all_pte_masks(); |
7054 | |
7055 | pte_list_desc_cache = KMEM_CACHE(pte_list_desc, SLAB_ACCOUNT); |
7056 | if (!pte_list_desc_cache) |
7057 | goto out; |
7058 | |
7059 | mmu_page_header_cache = kmem_cache_create(name: "kvm_mmu_page_header" , |
7060 | size: sizeof(struct kvm_mmu_page), |
7061 | align: 0, SLAB_ACCOUNT, NULL); |
7062 | if (!mmu_page_header_cache) |
7063 | goto out; |
7064 | |
7065 | if (percpu_counter_init(&kvm_total_used_mmu_pages, 0, GFP_KERNEL)) |
7066 | goto out; |
7067 | |
7068 | mmu_shrinker = shrinker_alloc(flags: 0, fmt: "x86-mmu" ); |
7069 | if (!mmu_shrinker) |
7070 | goto out_shrinker; |
7071 | |
7072 | mmu_shrinker->count_objects = mmu_shrink_count; |
7073 | mmu_shrinker->scan_objects = mmu_shrink_scan; |
7074 | mmu_shrinker->seeks = DEFAULT_SEEKS * 10; |
7075 | |
7076 | shrinker_register(shrinker: mmu_shrinker); |
7077 | |
7078 | return 0; |
7079 | |
7080 | out_shrinker: |
7081 | percpu_counter_destroy(fbc: &kvm_total_used_mmu_pages); |
7082 | out: |
7083 | mmu_destroy_caches(); |
7084 | return ret; |
7085 | } |
7086 | |
7087 | void kvm_mmu_destroy(struct kvm_vcpu *vcpu) |
7088 | { |
7089 | kvm_mmu_unload(vcpu); |
7090 | free_mmu_pages(mmu: &vcpu->arch.root_mmu); |
7091 | free_mmu_pages(mmu: &vcpu->arch.guest_mmu); |
7092 | mmu_free_memory_caches(vcpu); |
7093 | } |
7094 | |
7095 | void kvm_mmu_vendor_module_exit(void) |
7096 | { |
7097 | mmu_destroy_caches(); |
7098 | percpu_counter_destroy(fbc: &kvm_total_used_mmu_pages); |
7099 | shrinker_free(shrinker: mmu_shrinker); |
7100 | } |
7101 | |
7102 | /* |
7103 | * Calculate the effective recovery period, accounting for '0' meaning "let KVM |
7104 | * select a halving time of 1 hour". Returns true if recovery is enabled. |
7105 | */ |
7106 | static bool calc_nx_huge_pages_recovery_period(uint *period) |
7107 | { |
7108 | /* |
7109 | * Use READ_ONCE to get the params, this may be called outside of the |
7110 | * param setters, e.g. by the kthread to compute its next timeout. |
7111 | */ |
7112 | bool enabled = READ_ONCE(nx_huge_pages); |
7113 | uint ratio = READ_ONCE(nx_huge_pages_recovery_ratio); |
7114 | |
7115 | if (!enabled || !ratio) |
7116 | return false; |
7117 | |
7118 | *period = READ_ONCE(nx_huge_pages_recovery_period_ms); |
7119 | if (!*period) { |
7120 | /* Make sure the period is not less than one second. */ |
7121 | ratio = min(ratio, 3600u); |
7122 | *period = 60 * 60 * 1000 / ratio; |
7123 | } |
7124 | return true; |
7125 | } |
7126 | |
7127 | static int set_nx_huge_pages_recovery_param(const char *val, const struct kernel_param *kp) |
7128 | { |
7129 | bool was_recovery_enabled, is_recovery_enabled; |
7130 | uint old_period, new_period; |
7131 | int err; |
7132 | |
7133 | if (nx_hugepage_mitigation_hard_disabled) |
7134 | return -EPERM; |
7135 | |
7136 | was_recovery_enabled = calc_nx_huge_pages_recovery_period(period: &old_period); |
7137 | |
7138 | err = param_set_uint(val, kp); |
7139 | if (err) |
7140 | return err; |
7141 | |
7142 | is_recovery_enabled = calc_nx_huge_pages_recovery_period(period: &new_period); |
7143 | |
7144 | if (is_recovery_enabled && |
7145 | (!was_recovery_enabled || old_period > new_period)) { |
7146 | struct kvm *kvm; |
7147 | |
7148 | mutex_lock(&kvm_lock); |
7149 | |
7150 | list_for_each_entry(kvm, &vm_list, vm_list) |
7151 | wake_up_process(tsk: kvm->arch.nx_huge_page_recovery_thread); |
7152 | |
7153 | mutex_unlock(lock: &kvm_lock); |
7154 | } |
7155 | |
7156 | return err; |
7157 | } |
7158 | |
7159 | static void kvm_recover_nx_huge_pages(struct kvm *kvm) |
7160 | { |
7161 | unsigned long nx_lpage_splits = kvm->stat.nx_lpage_splits; |
7162 | struct kvm_memory_slot *slot; |
7163 | int rcu_idx; |
7164 | struct kvm_mmu_page *sp; |
7165 | unsigned int ratio; |
7166 | LIST_HEAD(invalid_list); |
7167 | bool flush = false; |
7168 | ulong to_zap; |
7169 | |
7170 | rcu_idx = srcu_read_lock(ssp: &kvm->srcu); |
7171 | write_lock(&kvm->mmu_lock); |
7172 | |
7173 | /* |
7174 | * Zapping TDP MMU shadow pages, including the remote TLB flush, must |
7175 | * be done under RCU protection, because the pages are freed via RCU |
7176 | * callback. |
7177 | */ |
7178 | rcu_read_lock(); |
7179 | |
7180 | ratio = READ_ONCE(nx_huge_pages_recovery_ratio); |
7181 | to_zap = ratio ? DIV_ROUND_UP(nx_lpage_splits, ratio) : 0; |
7182 | for ( ; to_zap; --to_zap) { |
7183 | if (list_empty(head: &kvm->arch.possible_nx_huge_pages)) |
7184 | break; |
7185 | |
7186 | /* |
7187 | * We use a separate list instead of just using active_mmu_pages |
7188 | * because the number of shadow pages that be replaced with an |
7189 | * NX huge page is expected to be relatively small compared to |
7190 | * the total number of shadow pages. And because the TDP MMU |
7191 | * doesn't use active_mmu_pages. |
7192 | */ |
7193 | sp = list_first_entry(&kvm->arch.possible_nx_huge_pages, |
7194 | struct kvm_mmu_page, |
7195 | possible_nx_huge_page_link); |
7196 | WARN_ON_ONCE(!sp->nx_huge_page_disallowed); |
7197 | WARN_ON_ONCE(!sp->role.direct); |
7198 | |
7199 | /* |
7200 | * Unaccount and do not attempt to recover any NX Huge Pages |
7201 | * that are being dirty tracked, as they would just be faulted |
7202 | * back in as 4KiB pages. The NX Huge Pages in this slot will be |
7203 | * recovered, along with all the other huge pages in the slot, |
7204 | * when dirty logging is disabled. |
7205 | * |
7206 | * Since gfn_to_memslot() is relatively expensive, it helps to |
7207 | * skip it if it the test cannot possibly return true. On the |
7208 | * other hand, if any memslot has logging enabled, chances are |
7209 | * good that all of them do, in which case unaccount_nx_huge_page() |
7210 | * is much cheaper than zapping the page. |
7211 | * |
7212 | * If a memslot update is in progress, reading an incorrect value |
7213 | * of kvm->nr_memslots_dirty_logging is not a problem: if it is |
7214 | * becoming zero, gfn_to_memslot() will be done unnecessarily; if |
7215 | * it is becoming nonzero, the page will be zapped unnecessarily. |
7216 | * Either way, this only affects efficiency in racy situations, |
7217 | * and not correctness. |
7218 | */ |
7219 | slot = NULL; |
7220 | if (atomic_read(v: &kvm->nr_memslots_dirty_logging)) { |
7221 | struct kvm_memslots *slots; |
7222 | |
7223 | slots = kvm_memslots_for_spte_role(kvm, sp->role); |
7224 | slot = __gfn_to_memslot(slots, gfn: sp->gfn); |
7225 | WARN_ON_ONCE(!slot); |
7226 | } |
7227 | |
7228 | if (slot && kvm_slot_dirty_track_enabled(slot)) |
7229 | unaccount_nx_huge_page(kvm, sp); |
7230 | else if (is_tdp_mmu_page(sp)) |
7231 | flush |= kvm_tdp_mmu_zap_sp(kvm, sp); |
7232 | else |
7233 | kvm_mmu_prepare_zap_page(kvm, sp, invalid_list: &invalid_list); |
7234 | WARN_ON_ONCE(sp->nx_huge_page_disallowed); |
7235 | |
7236 | if (need_resched() || rwlock_needbreak(lock: &kvm->mmu_lock)) { |
7237 | kvm_mmu_remote_flush_or_zap(kvm, invalid_list: &invalid_list, remote_flush: flush); |
7238 | rcu_read_unlock(); |
7239 | |
7240 | cond_resched_rwlock_write(&kvm->mmu_lock); |
7241 | flush = false; |
7242 | |
7243 | rcu_read_lock(); |
7244 | } |
7245 | } |
7246 | kvm_mmu_remote_flush_or_zap(kvm, invalid_list: &invalid_list, remote_flush: flush); |
7247 | |
7248 | rcu_read_unlock(); |
7249 | |
7250 | write_unlock(&kvm->mmu_lock); |
7251 | srcu_read_unlock(ssp: &kvm->srcu, idx: rcu_idx); |
7252 | } |
7253 | |
7254 | static long get_nx_huge_page_recovery_timeout(u64 start_time) |
7255 | { |
7256 | bool enabled; |
7257 | uint period; |
7258 | |
7259 | enabled = calc_nx_huge_pages_recovery_period(period: &period); |
7260 | |
7261 | return enabled ? start_time + msecs_to_jiffies(m: period) - get_jiffies_64() |
7262 | : MAX_SCHEDULE_TIMEOUT; |
7263 | } |
7264 | |
7265 | static int kvm_nx_huge_page_recovery_worker(struct kvm *kvm, uintptr_t data) |
7266 | { |
7267 | u64 start_time; |
7268 | long remaining_time; |
7269 | |
7270 | while (true) { |
7271 | start_time = get_jiffies_64(); |
7272 | remaining_time = get_nx_huge_page_recovery_timeout(start_time); |
7273 | |
7274 | set_current_state(TASK_INTERRUPTIBLE); |
7275 | while (!kthread_should_stop() && remaining_time > 0) { |
7276 | schedule_timeout(timeout: remaining_time); |
7277 | remaining_time = get_nx_huge_page_recovery_timeout(start_time); |
7278 | set_current_state(TASK_INTERRUPTIBLE); |
7279 | } |
7280 | |
7281 | set_current_state(TASK_RUNNING); |
7282 | |
7283 | if (kthread_should_stop()) |
7284 | return 0; |
7285 | |
7286 | kvm_recover_nx_huge_pages(kvm); |
7287 | } |
7288 | } |
7289 | |
7290 | int kvm_mmu_post_init_vm(struct kvm *kvm) |
7291 | { |
7292 | int err; |
7293 | |
7294 | if (nx_hugepage_mitigation_hard_disabled) |
7295 | return 0; |
7296 | |
7297 | err = kvm_vm_create_worker_thread(kvm, thread_fn: kvm_nx_huge_page_recovery_worker, data: 0, |
7298 | name: "kvm-nx-lpage-recovery" , |
7299 | thread_ptr: &kvm->arch.nx_huge_page_recovery_thread); |
7300 | if (!err) |
7301 | kthread_unpark(k: kvm->arch.nx_huge_page_recovery_thread); |
7302 | |
7303 | return err; |
7304 | } |
7305 | |
7306 | void kvm_mmu_pre_destroy_vm(struct kvm *kvm) |
7307 | { |
7308 | if (kvm->arch.nx_huge_page_recovery_thread) |
7309 | kthread_stop(k: kvm->arch.nx_huge_page_recovery_thread); |
7310 | } |
7311 | |
7312 | #ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES |
7313 | bool kvm_arch_pre_set_memory_attributes(struct kvm *kvm, |
7314 | struct kvm_gfn_range *range) |
7315 | { |
7316 | /* |
7317 | * Zap SPTEs even if the slot can't be mapped PRIVATE. KVM x86 only |
7318 | * supports KVM_MEMORY_ATTRIBUTE_PRIVATE, and so it *seems* like KVM |
7319 | * can simply ignore such slots. But if userspace is making memory |
7320 | * PRIVATE, then KVM must prevent the guest from accessing the memory |
7321 | * as shared. And if userspace is making memory SHARED and this point |
7322 | * is reached, then at least one page within the range was previously |
7323 | * PRIVATE, i.e. the slot's possible hugepage ranges are changing. |
7324 | * Zapping SPTEs in this case ensures KVM will reassess whether or not |
7325 | * a hugepage can be used for affected ranges. |
7326 | */ |
7327 | if (WARN_ON_ONCE(!kvm_arch_has_private_mem(kvm))) |
7328 | return false; |
7329 | |
7330 | return kvm_unmap_gfn_range(kvm, range); |
7331 | } |
7332 | |
7333 | static bool hugepage_test_mixed(struct kvm_memory_slot *slot, gfn_t gfn, |
7334 | int level) |
7335 | { |
7336 | return lpage_info_slot(gfn, slot, level)->disallow_lpage & KVM_LPAGE_MIXED_FLAG; |
7337 | } |
7338 | |
7339 | static void hugepage_clear_mixed(struct kvm_memory_slot *slot, gfn_t gfn, |
7340 | int level) |
7341 | { |
7342 | lpage_info_slot(gfn, slot, level)->disallow_lpage &= ~KVM_LPAGE_MIXED_FLAG; |
7343 | } |
7344 | |
7345 | static void hugepage_set_mixed(struct kvm_memory_slot *slot, gfn_t gfn, |
7346 | int level) |
7347 | { |
7348 | lpage_info_slot(gfn, slot, level)->disallow_lpage |= KVM_LPAGE_MIXED_FLAG; |
7349 | } |
7350 | |
7351 | static bool hugepage_has_attrs(struct kvm *kvm, struct kvm_memory_slot *slot, |
7352 | gfn_t gfn, int level, unsigned long attrs) |
7353 | { |
7354 | const unsigned long start = gfn; |
7355 | const unsigned long end = start + KVM_PAGES_PER_HPAGE(level); |
7356 | |
7357 | if (level == PG_LEVEL_2M) |
7358 | return kvm_range_has_memory_attributes(kvm, start, end, attrs); |
7359 | |
7360 | for (gfn = start; gfn < end; gfn += KVM_PAGES_PER_HPAGE(level - 1)) { |
7361 | if (hugepage_test_mixed(slot, gfn, level: level - 1) || |
7362 | attrs != kvm_get_memory_attributes(kvm, gfn)) |
7363 | return false; |
7364 | } |
7365 | return true; |
7366 | } |
7367 | |
7368 | bool kvm_arch_post_set_memory_attributes(struct kvm *kvm, |
7369 | struct kvm_gfn_range *range) |
7370 | { |
7371 | unsigned long attrs = range->arg.attributes; |
7372 | struct kvm_memory_slot *slot = range->slot; |
7373 | int level; |
7374 | |
7375 | lockdep_assert_held_write(&kvm->mmu_lock); |
7376 | lockdep_assert_held(&kvm->slots_lock); |
7377 | |
7378 | /* |
7379 | * Calculate which ranges can be mapped with hugepages even if the slot |
7380 | * can't map memory PRIVATE. KVM mustn't create a SHARED hugepage over |
7381 | * a range that has PRIVATE GFNs, and conversely converting a range to |
7382 | * SHARED may now allow hugepages. |
7383 | */ |
7384 | if (WARN_ON_ONCE(!kvm_arch_has_private_mem(kvm))) |
7385 | return false; |
7386 | |
7387 | /* |
7388 | * The sequence matters here: upper levels consume the result of lower |
7389 | * level's scanning. |
7390 | */ |
7391 | for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) { |
7392 | gfn_t nr_pages = KVM_PAGES_PER_HPAGE(level); |
7393 | gfn_t gfn = gfn_round_for_level(gfn: range->start, level); |
7394 | |
7395 | /* Process the head page if it straddles the range. */ |
7396 | if (gfn != range->start || gfn + nr_pages > range->end) { |
7397 | /* |
7398 | * Skip mixed tracking if the aligned gfn isn't covered |
7399 | * by the memslot, KVM can't use a hugepage due to the |
7400 | * misaligned address regardless of memory attributes. |
7401 | */ |
7402 | if (gfn >= slot->base_gfn && |
7403 | gfn + nr_pages <= slot->base_gfn + slot->npages) { |
7404 | if (hugepage_has_attrs(kvm, slot, gfn, level, attrs)) |
7405 | hugepage_clear_mixed(slot, gfn, level); |
7406 | else |
7407 | hugepage_set_mixed(slot, gfn, level); |
7408 | } |
7409 | gfn += nr_pages; |
7410 | } |
7411 | |
7412 | /* |
7413 | * Pages entirely covered by the range are guaranteed to have |
7414 | * only the attributes which were just set. |
7415 | */ |
7416 | for ( ; gfn + nr_pages <= range->end; gfn += nr_pages) |
7417 | hugepage_clear_mixed(slot, gfn, level); |
7418 | |
7419 | /* |
7420 | * Process the last tail page if it straddles the range and is |
7421 | * contained by the memslot. Like the head page, KVM can't |
7422 | * create a hugepage if the slot size is misaligned. |
7423 | */ |
7424 | if (gfn < range->end && |
7425 | (gfn + nr_pages) <= (slot->base_gfn + slot->npages)) { |
7426 | if (hugepage_has_attrs(kvm, slot, gfn, level, attrs)) |
7427 | hugepage_clear_mixed(slot, gfn, level); |
7428 | else |
7429 | hugepage_set_mixed(slot, gfn, level); |
7430 | } |
7431 | } |
7432 | return false; |
7433 | } |
7434 | |
7435 | void kvm_mmu_init_memslot_memory_attributes(struct kvm *kvm, |
7436 | struct kvm_memory_slot *slot) |
7437 | { |
7438 | int level; |
7439 | |
7440 | if (!kvm_arch_has_private_mem(kvm)) |
7441 | return; |
7442 | |
7443 | for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) { |
7444 | /* |
7445 | * Don't bother tracking mixed attributes for pages that can't |
7446 | * be huge due to alignment, i.e. process only pages that are |
7447 | * entirely contained by the memslot. |
7448 | */ |
7449 | gfn_t end = gfn_round_for_level(gfn: slot->base_gfn + slot->npages, level); |
7450 | gfn_t start = gfn_round_for_level(gfn: slot->base_gfn, level); |
7451 | gfn_t nr_pages = KVM_PAGES_PER_HPAGE(level); |
7452 | gfn_t gfn; |
7453 | |
7454 | if (start < slot->base_gfn) |
7455 | start += nr_pages; |
7456 | |
7457 | /* |
7458 | * Unlike setting attributes, every potential hugepage needs to |
7459 | * be manually checked as the attributes may already be mixed. |
7460 | */ |
7461 | for (gfn = start; gfn < end; gfn += nr_pages) { |
7462 | unsigned long attrs = kvm_get_memory_attributes(kvm, gfn); |
7463 | |
7464 | if (hugepage_has_attrs(kvm, slot, gfn, level, attrs)) |
7465 | hugepage_clear_mixed(slot, gfn, level); |
7466 | else |
7467 | hugepage_set_mixed(slot, gfn, level); |
7468 | } |
7469 | } |
7470 | } |
7471 | #endif |
7472 | |