1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Debug helper used to dump the stage-2 pagetables of the system and their
4 * associated permissions.
5 *
6 * Copyright (C) Google, 2024
7 * Author: Sebastian Ene <sebastianene@google.com>
8 */
9#include <linux/debugfs.h>
10#include <linux/kvm_host.h>
11#include <linux/seq_file.h>
12
13#include <asm/kvm_mmu.h>
14#include <asm/kvm_pgtable.h>
15#include <asm/ptdump.h>
16
17#define MARKERS_LEN 2
18#define KVM_PGTABLE_MAX_LEVELS (KVM_PGTABLE_LAST_LEVEL + 1)
19
20struct kvm_ptdump_guest_state {
21 struct kvm *kvm;
22 struct ptdump_pg_state parser_state;
23 struct addr_marker ipa_marker[MARKERS_LEN];
24 struct ptdump_pg_level level[KVM_PGTABLE_MAX_LEVELS];
25 struct ptdump_range range[MARKERS_LEN];
26};
27
28static const struct ptdump_prot_bits stage2_pte_bits[] = {
29 {
30 .mask = PTE_VALID,
31 .val = PTE_VALID,
32 .set = " ",
33 .clear = "F",
34 },
35 {
36 .mask = KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R,
37 .val = KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R,
38 .set = "R",
39 .clear = " ",
40 },
41 {
42 .mask = KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W,
43 .val = KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W,
44 .set = "W",
45 .clear = " ",
46 },
47 {
48 .mask = KVM_PTE_LEAF_ATTR_HI_S2_XN,
49 .val = 0b00UL << __bf_shf(KVM_PTE_LEAF_ATTR_HI_S2_XN),
50 .set = "px ux ",
51 },
52 {
53 .mask = KVM_PTE_LEAF_ATTR_HI_S2_XN,
54 .val = 0b01UL << __bf_shf(KVM_PTE_LEAF_ATTR_HI_S2_XN),
55 .set = "PXNux ",
56 },
57 {
58 .mask = KVM_PTE_LEAF_ATTR_HI_S2_XN,
59 .val = 0b10UL << __bf_shf(KVM_PTE_LEAF_ATTR_HI_S2_XN),
60 .set = "PXNUXN",
61 },
62 {
63 .mask = KVM_PTE_LEAF_ATTR_HI_S2_XN,
64 .val = 0b11UL << __bf_shf(KVM_PTE_LEAF_ATTR_HI_S2_XN),
65 .set = "px UXN",
66 },
67 {
68 .mask = KVM_PTE_LEAF_ATTR_LO_S2_AF,
69 .val = KVM_PTE_LEAF_ATTR_LO_S2_AF,
70 .set = "AF",
71 .clear = " ",
72 },
73 {
74 .mask = PMD_TYPE_MASK,
75 .val = PMD_TYPE_SECT,
76 .set = "BLK",
77 .clear = " ",
78 },
79};
80
81static int kvm_ptdump_visitor(const struct kvm_pgtable_visit_ctx *ctx,
82 enum kvm_pgtable_walk_flags visit)
83{
84 struct ptdump_pg_state *st = ctx->arg;
85 struct ptdump_state *pt_st = &st->ptdump;
86
87 note_page(pt_st, ctx->addr, ctx->level, ctx->old);
88
89 return 0;
90}
91
92static int kvm_ptdump_build_levels(struct ptdump_pg_level *level, u32 start_lvl)
93{
94 u32 i;
95 u64 mask;
96
97 if (WARN_ON_ONCE(start_lvl >= KVM_PGTABLE_LAST_LEVEL))
98 return -EINVAL;
99
100 mask = 0;
101 for (i = 0; i < ARRAY_SIZE(stage2_pte_bits); i++)
102 mask |= stage2_pte_bits[i].mask;
103
104 for (i = start_lvl; i < KVM_PGTABLE_MAX_LEVELS; i++) {
105 snprintf(level[i].name, sizeof(level[i].name), "%u", i);
106
107 level[i].num = ARRAY_SIZE(stage2_pte_bits);
108 level[i].bits = stage2_pte_bits;
109 level[i].mask = mask;
110 }
111
112 return 0;
113}
114
115static struct kvm_ptdump_guest_state *kvm_ptdump_parser_create(struct kvm *kvm)
116{
117 struct kvm_ptdump_guest_state *st;
118 struct kvm_s2_mmu *mmu = &kvm->arch.mmu;
119 struct kvm_pgtable *pgtable = mmu->pgt;
120 int ret;
121
122 st = kzalloc(sizeof(struct kvm_ptdump_guest_state), GFP_KERNEL_ACCOUNT);
123 if (!st)
124 return ERR_PTR(error: -ENOMEM);
125
126 ret = kvm_ptdump_build_levels(level: &st->level[0], start_lvl: pgtable->start_level);
127 if (ret) {
128 kfree(objp: st);
129 return ERR_PTR(error: ret);
130 }
131
132 st->ipa_marker[0].name = "Guest IPA";
133 st->ipa_marker[1].start_address = BIT(pgtable->ia_bits);
134 st->range[0].end = BIT(pgtable->ia_bits);
135
136 st->kvm = kvm;
137 st->parser_state = (struct ptdump_pg_state) {
138 .marker = &st->ipa_marker[0],
139 .level = -1,
140 .pg_level = &st->level[0],
141 .ptdump.range = &st->range[0],
142 .start_address = 0,
143 };
144
145 return st;
146}
147
148static int kvm_ptdump_guest_show(struct seq_file *m, void *unused)
149{
150 int ret;
151 struct kvm_ptdump_guest_state *st = m->private;
152 struct kvm *kvm = st->kvm;
153 struct kvm_s2_mmu *mmu = &kvm->arch.mmu;
154 struct ptdump_pg_state *parser_state = &st->parser_state;
155 struct kvm_pgtable_walker walker = (struct kvm_pgtable_walker) {
156 .cb = kvm_ptdump_visitor,
157 .arg = parser_state,
158 .flags = KVM_PGTABLE_WALK_LEAF,
159 };
160
161 parser_state->seq = m;
162
163 write_lock(&kvm->mmu_lock);
164 ret = kvm_pgtable_walk(mmu->pgt, 0, BIT(mmu->pgt->ia_bits), &walker);
165 write_unlock(&kvm->mmu_lock);
166
167 return ret;
168}
169
170static int kvm_ptdump_guest_open(struct inode *m, struct file *file)
171{
172 struct kvm *kvm = m->i_private;
173 struct kvm_ptdump_guest_state *st;
174 int ret;
175
176 if (!kvm_get_kvm_safe(kvm))
177 return -ENOENT;
178
179 st = kvm_ptdump_parser_create(kvm);
180 if (IS_ERR(ptr: st)) {
181 ret = PTR_ERR(ptr: st);
182 goto err_with_kvm_ref;
183 }
184
185 ret = single_open(file, kvm_ptdump_guest_show, st);
186 if (!ret)
187 return 0;
188
189 kfree(objp: st);
190err_with_kvm_ref:
191 kvm_put_kvm(kvm);
192 return ret;
193}
194
195static int kvm_ptdump_guest_close(struct inode *m, struct file *file)
196{
197 struct kvm *kvm = m->i_private;
198 void *st = ((struct seq_file *)file->private_data)->private;
199
200 kfree(objp: st);
201 kvm_put_kvm(kvm);
202
203 return single_release(m, file);
204}
205
206static const struct file_operations kvm_ptdump_guest_fops = {
207 .open = kvm_ptdump_guest_open,
208 .read = seq_read,
209 .llseek = seq_lseek,
210 .release = kvm_ptdump_guest_close,
211};
212
213static int kvm_pgtable_range_show(struct seq_file *m, void *unused)
214{
215 struct kvm_pgtable *pgtable = m->private;
216
217 seq_printf(m, fmt: "%2u\n", pgtable->ia_bits);
218 return 0;
219}
220
221static int kvm_pgtable_levels_show(struct seq_file *m, void *unused)
222{
223 struct kvm_pgtable *pgtable = m->private;
224
225 seq_printf(m, "%1d\n", KVM_PGTABLE_MAX_LEVELS - pgtable->start_level);
226 return 0;
227}
228
229static int kvm_pgtable_debugfs_open(struct inode *m, struct file *file,
230 int (*show)(struct seq_file *, void *))
231{
232 struct kvm *kvm = m->i_private;
233 struct kvm_pgtable *pgtable;
234 int ret;
235
236 if (!kvm_get_kvm_safe(kvm))
237 return -ENOENT;
238
239 pgtable = kvm->arch.mmu.pgt;
240
241 ret = single_open(file, show, pgtable);
242 if (ret < 0)
243 kvm_put_kvm(kvm);
244 return ret;
245}
246
247static int kvm_pgtable_range_open(struct inode *m, struct file *file)
248{
249 return kvm_pgtable_debugfs_open(m, file, show: kvm_pgtable_range_show);
250}
251
252static int kvm_pgtable_levels_open(struct inode *m, struct file *file)
253{
254 return kvm_pgtable_debugfs_open(m, file, show: kvm_pgtable_levels_show);
255}
256
257static int kvm_pgtable_debugfs_close(struct inode *m, struct file *file)
258{
259 struct kvm *kvm = m->i_private;
260
261 kvm_put_kvm(kvm);
262 return single_release(m, file);
263}
264
265static const struct file_operations kvm_pgtable_range_fops = {
266 .open = kvm_pgtable_range_open,
267 .read = seq_read,
268 .llseek = seq_lseek,
269 .release = kvm_pgtable_debugfs_close,
270};
271
272static const struct file_operations kvm_pgtable_levels_fops = {
273 .open = kvm_pgtable_levels_open,
274 .read = seq_read,
275 .llseek = seq_lseek,
276 .release = kvm_pgtable_debugfs_close,
277};
278
279void kvm_s2_ptdump_create_debugfs(struct kvm *kvm)
280{
281 debugfs_create_file("stage2_page_tables", 0400, kvm->debugfs_dentry,
282 kvm, &kvm_ptdump_guest_fops);
283 debugfs_create_file("ipa_range", 0400, kvm->debugfs_dentry, kvm,
284 &kvm_pgtable_range_fops);
285 debugfs_create_file("stage2_levels", 0400, kvm->debugfs_dentry,
286 kvm, &kvm_pgtable_levels_fops);
287}
288

source code of linux/arch/arm64/kvm/ptdump.c