1// SPDX-License-Identifier: GPL-2.0
2/*
3 * handling diagnose instructions
4 *
5 * Copyright IBM Corp. 2008, 2020
6 *
7 * Author(s): Carsten Otte <cotte@de.ibm.com>
8 * Christian Borntraeger <borntraeger@de.ibm.com>
9 */
10
11#include <linux/kvm.h>
12#include <linux/kvm_host.h>
13#include <asm/gmap.h>
14#include <asm/gmap_helpers.h>
15#include <asm/virtio-ccw.h>
16#include "kvm-s390.h"
17#include "trace.h"
18#include "trace-s390.h"
19#include "gaccess.h"
20
21static void do_discard_gfn_range(struct kvm_vcpu *vcpu, gfn_t gfn_start, gfn_t gfn_end)
22{
23 struct kvm_memslot_iter iter;
24 struct kvm_memory_slot *slot;
25 struct kvm_memslots *slots;
26 unsigned long start, end;
27
28 slots = kvm_vcpu_memslots(vcpu);
29
30 kvm_for_each_memslot_in_gfn_range(&iter, slots, gfn_start, gfn_end) {
31 slot = iter.slot;
32 start = __gfn_to_hva_memslot(slot, max(gfn_start, slot->base_gfn));
33 end = __gfn_to_hva_memslot(slot, min(gfn_end, slot->base_gfn + slot->npages));
34 gmap_helper_discard(vcpu->kvm->mm, start, end);
35 }
36}
37
38static int diag_release_pages(struct kvm_vcpu *vcpu)
39{
40 unsigned long start, end;
41 unsigned long prefix = kvm_s390_get_prefix(vcpu);
42
43 start = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
44 end = vcpu->run->s.regs.gprs[vcpu->arch.sie_block->ipa & 0xf] + PAGE_SIZE;
45 vcpu->stat.instruction_diagnose_10++;
46
47 if (start & ~PAGE_MASK || end & ~PAGE_MASK || start >= end
48 || start < 2 * PAGE_SIZE)
49 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
50
51 VCPU_EVENT(vcpu, 5, "diag release pages %lX %lX", start, end);
52
53 mmap_read_lock(mm: vcpu->kvm->mm);
54 /*
55 * We checked for start >= end above, so lets check for the
56 * fast path (no prefix swap page involved)
57 */
58 if (end <= prefix || start >= prefix + 2 * PAGE_SIZE) {
59 do_discard_gfn_range(vcpu, gfn_start: gpa_to_gfn(gpa: start), gfn_end: gpa_to_gfn(gpa: end));
60 } else {
61 /*
62 * This is slow path. gmap_discard will check for start
63 * so lets split this into before prefix, prefix, after
64 * prefix and let gmap_discard make some of these calls
65 * NOPs.
66 */
67 do_discard_gfn_range(vcpu, gfn_start: gpa_to_gfn(gpa: start), gfn_end: gpa_to_gfn(gpa: prefix));
68 if (start <= prefix)
69 do_discard_gfn_range(vcpu, gfn_start: 0, gfn_end: 1);
70 if (end > prefix + PAGE_SIZE)
71 do_discard_gfn_range(vcpu, gfn_start: 1, gfn_end: 2);
72 do_discard_gfn_range(vcpu, gfn_start: gpa_to_gfn(gpa: prefix) + 2, gfn_end: gpa_to_gfn(gpa: end));
73 }
74 mmap_read_unlock(mm: vcpu->kvm->mm);
75 return 0;
76}
77
78static int __diag_page_ref_service(struct kvm_vcpu *vcpu)
79{
80 struct prs_parm {
81 u16 code;
82 u16 subcode;
83 u16 parm_len;
84 u16 parm_version;
85 u64 token_addr;
86 u64 select_mask;
87 u64 compare_mask;
88 u64 zarch;
89 };
90 struct prs_parm parm;
91 int rc;
92 u16 rx = (vcpu->arch.sie_block->ipa & 0xf0) >> 4;
93 u16 ry = (vcpu->arch.sie_block->ipa & 0x0f);
94
95 VCPU_EVENT(vcpu, 3, "diag page reference parameter block at 0x%llx",
96 vcpu->run->s.regs.gprs[rx]);
97 vcpu->stat.instruction_diagnose_258++;
98 if (vcpu->run->s.regs.gprs[rx] & 7)
99 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
100 rc = read_guest_real(vcpu, gra: vcpu->run->s.regs.gprs[rx], data: &parm, len: sizeof(parm));
101 if (rc)
102 return kvm_s390_inject_prog_cond(vcpu, rc);
103 if (parm.parm_version != 2 || parm.parm_len < 5 || parm.code != 0x258)
104 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
105
106 switch (parm.subcode) {
107 case 0: /* TOKEN */
108 VCPU_EVENT(vcpu, 3, "pageref token addr 0x%llx "
109 "select mask 0x%llx compare mask 0x%llx",
110 parm.token_addr, parm.select_mask, parm.compare_mask);
111 if (vcpu->arch.pfault_token != KVM_S390_PFAULT_TOKEN_INVALID) {
112 /*
113 * If the pagefault handshake is already activated,
114 * the token must not be changed. We have to return
115 * decimal 8 instead, as mandated in SC24-6084.
116 */
117 vcpu->run->s.regs.gprs[ry] = 8;
118 return 0;
119 }
120
121 if ((parm.compare_mask & parm.select_mask) != parm.compare_mask ||
122 parm.token_addr & 7 || parm.zarch != 0x8000000000000000ULL)
123 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
124
125 if (!kvm_is_gpa_in_memslot(vcpu->kvm, parm.token_addr))
126 return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
127
128 vcpu->arch.pfault_token = parm.token_addr;
129 vcpu->arch.pfault_select = parm.select_mask;
130 vcpu->arch.pfault_compare = parm.compare_mask;
131 vcpu->run->s.regs.gprs[ry] = 0;
132 rc = 0;
133 break;
134 case 1: /*
135 * CANCEL
136 * Specification allows to let already pending tokens survive
137 * the cancel, therefore to reduce code complexity, we assume
138 * all outstanding tokens are already pending.
139 */
140 VCPU_EVENT(vcpu, 3, "pageref cancel addr 0x%llx", parm.token_addr);
141 if (parm.token_addr || parm.select_mask ||
142 parm.compare_mask || parm.zarch)
143 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
144
145 vcpu->run->s.regs.gprs[ry] = 0;
146 /*
147 * If the pfault handling was not established or is already
148 * canceled SC24-6084 requests to return decimal 4.
149 */
150 if (vcpu->arch.pfault_token == KVM_S390_PFAULT_TOKEN_INVALID)
151 vcpu->run->s.regs.gprs[ry] = 4;
152 else
153 vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
154
155 rc = 0;
156 break;
157 default:
158 rc = -EOPNOTSUPP;
159 break;
160 }
161
162 return rc;
163}
164
165static int __diag_time_slice_end(struct kvm_vcpu *vcpu)
166{
167 VCPU_EVENT(vcpu, 5, "%s", "diag time slice end");
168 vcpu->stat.instruction_diagnose_44++;
169 kvm_vcpu_on_spin(vcpu, yield_to_kernel_mode: true);
170 return 0;
171}
172
173static int forward_cnt;
174static unsigned long cur_slice;
175
176static int diag9c_forwarding_overrun(void)
177{
178 /* Reset the count on a new slice */
179 if (time_after(jiffies, cur_slice)) {
180 cur_slice = jiffies;
181 forward_cnt = diag9c_forwarding_hz / HZ;
182 }
183 return forward_cnt-- <= 0 ? 1 : 0;
184}
185
186static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu)
187{
188 struct kvm_vcpu *tcpu;
189 int tcpu_cpu;
190 int tid;
191
192 tid = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
193 vcpu->stat.instruction_diagnose_9c++;
194
195 /* yield to self */
196 if (tid == vcpu->vcpu_id)
197 goto no_yield;
198
199 /* yield to invalid */
200 tcpu = kvm_get_vcpu_by_id(kvm: vcpu->kvm, id: tid);
201 if (!tcpu)
202 goto no_yield;
203
204 /* target guest VCPU already running */
205 tcpu_cpu = READ_ONCE(tcpu->cpu);
206 if (tcpu_cpu >= 0) {
207 if (!diag9c_forwarding_hz || diag9c_forwarding_overrun())
208 goto no_yield;
209
210 /* target host CPU already running */
211 if (!vcpu_is_preempted(cpu: tcpu_cpu))
212 goto no_yield;
213 smp_yield_cpu(tcpu_cpu);
214 VCPU_EVENT(vcpu, 5,
215 "diag time slice end directed to %d: yield forwarded",
216 tid);
217 vcpu->stat.diag_9c_forward++;
218 return 0;
219 }
220
221 if (kvm_vcpu_yield_to(target: tcpu) <= 0)
222 goto no_yield;
223
224 VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: done", tid);
225 return 0;
226no_yield:
227 VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: ignored", tid);
228 vcpu->stat.diag_9c_ignored++;
229 return 0;
230}
231
232static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
233{
234 unsigned int reg = vcpu->arch.sie_block->ipa & 0xf;
235 unsigned long subcode = vcpu->run->s.regs.gprs[reg] & 0xffff;
236
237 VCPU_EVENT(vcpu, 3, "diag ipl functions, subcode %lx", subcode);
238 vcpu->stat.instruction_diagnose_308++;
239 switch (subcode) {
240 case 3:
241 vcpu->run->s390_reset_flags = KVM_S390_RESET_CLEAR;
242 break;
243 case 4:
244 vcpu->run->s390_reset_flags = 0;
245 break;
246 default:
247 return -EOPNOTSUPP;
248 }
249
250 /*
251 * no need to check the return value of vcpu_stop as it can only have
252 * an error for protvirt, but protvirt means user cpu state
253 */
254 if (!kvm_s390_user_cpu_state_ctrl(kvm: vcpu->kvm))
255 kvm_s390_vcpu_stop(vcpu);
256 vcpu->run->s390_reset_flags |= KVM_S390_RESET_SUBSYSTEM;
257 vcpu->run->s390_reset_flags |= KVM_S390_RESET_IPL;
258 vcpu->run->s390_reset_flags |= KVM_S390_RESET_CPU_INIT;
259 vcpu->run->exit_reason = KVM_EXIT_S390_RESET;
260 VCPU_EVENT(vcpu, 3, "requesting userspace resets %llx",
261 vcpu->run->s390_reset_flags);
262 trace_kvm_s390_request_resets(resets: vcpu->run->s390_reset_flags);
263 return -EREMOTE;
264}
265
266static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
267{
268 int ret;
269
270 vcpu->stat.instruction_diagnose_500++;
271 /* No virtio-ccw notification? Get out quickly. */
272 if (!vcpu->kvm->arch.css_support ||
273 (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY))
274 return -EOPNOTSUPP;
275
276 VCPU_EVENT(vcpu, 4, "diag 0x500 schid 0x%8.8x queue 0x%x cookie 0x%llx",
277 (u32) vcpu->run->s.regs.gprs[2],
278 (u32) vcpu->run->s.regs.gprs[3],
279 vcpu->run->s.regs.gprs[4]);
280
281 /*
282 * The layout is as follows:
283 * - gpr 2 contains the subchannel id (passed as addr)
284 * - gpr 3 contains the virtqueue index (passed as datamatch)
285 * - gpr 4 contains the index on the bus (optionally)
286 */
287 ret = kvm_io_bus_write_cookie(vcpu, bus_idx: KVM_VIRTIO_CCW_NOTIFY_BUS,
288 addr: vcpu->run->s.regs.gprs[2] & 0xffffffff,
289 len: 8, val: &vcpu->run->s.regs.gprs[3],
290 cookie: vcpu->run->s.regs.gprs[4]);
291
292 /*
293 * Return cookie in gpr 2, but don't overwrite the register if the
294 * diagnose will be handled by userspace.
295 */
296 if (ret != -EOPNOTSUPP)
297 vcpu->run->s.regs.gprs[2] = ret;
298 /* kvm_io_bus_write_cookie returns -EOPNOTSUPP if it found no match. */
299 return ret < 0 ? ret : 0;
300}
301
302int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
303{
304 int code = kvm_s390_get_base_disp_rs(vcpu, NULL) & 0xffff;
305
306 if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
307 return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
308
309 trace_kvm_s390_handle_diag(vcpu, code);
310 switch (code) {
311 case 0x10:
312 return diag_release_pages(vcpu);
313 case 0x44:
314 return __diag_time_slice_end(vcpu);
315 case 0x9c:
316 return __diag_time_slice_end_directed(vcpu);
317 case 0x258:
318 return __diag_page_ref_service(vcpu);
319 case 0x308:
320 return __diag_ipl_functions(vcpu);
321 case 0x500:
322 return __diag_virtio_hypercall(vcpu);
323 default:
324 vcpu->stat.instruction_diagnose_other++;
325 return -EOPNOTSUPP;
326 }
327}
328

source code of linux/arch/s390/kvm/diag.c