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Commit | Line | Data |
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2f4f3372 XG |
1 | /* |
2 | * mmu_audit.c: | |
3 | * | |
4 | * Audit code for KVM MMU | |
5 | * | |
6 | * Copyright (C) 2006 Qumranet, Inc. | |
9611c187 | 7 | * Copyright 2010 Red Hat, Inc. and/or its affiliates. |
2f4f3372 XG |
8 | * |
9 | * Authors: | |
10 | * Yaniv Kamay <yaniv@qumranet.com> | |
11 | * Avi Kivity <avi@qumranet.com> | |
12 | * Marcelo Tosatti <mtosatti@redhat.com> | |
13 | * Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> | |
14 | * | |
15 | * This work is licensed under the terms of the GNU GPL, version 2. See | |
16 | * the COPYING file in the top-level directory. | |
17 | * | |
18 | */ | |
19 | ||
30644b90 XG |
20 | #include <linux/ratelimit.h> |
21 | ||
38904e12 XG |
22 | static int audit_point; |
23 | ||
24 | #define audit_printk(fmt, args...) \ | |
25 | printk(KERN_ERR "audit: (%s) error: " \ | |
26 | fmt, audit_point_name[audit_point], ##args) | |
2f4f3372 | 27 | |
eb259186 | 28 | typedef void (*inspect_spte_fn) (struct kvm_vcpu *vcpu, u64 *sptep, int level); |
2f4f3372 | 29 | |
eb259186 XG |
30 | static void __mmu_spte_walk(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, |
31 | inspect_spte_fn fn, int level) | |
2f4f3372 XG |
32 | { |
33 | int i; | |
34 | ||
35 | for (i = 0; i < PT64_ENT_PER_PAGE; ++i) { | |
eb259186 XG |
36 | u64 *ent = sp->spt; |
37 | ||
38 | fn(vcpu, ent + i, level); | |
39 | ||
40 | if (is_shadow_present_pte(ent[i]) && | |
41 | !is_last_spte(ent[i], level)) { | |
42 | struct kvm_mmu_page *child; | |
43 | ||
44 | child = page_header(ent[i] & PT64_BASE_ADDR_MASK); | |
45 | __mmu_spte_walk(vcpu, child, fn, level - 1); | |
2f4f3372 XG |
46 | } |
47 | } | |
48 | } | |
49 | ||
50 | static void mmu_spte_walk(struct kvm_vcpu *vcpu, inspect_spte_fn fn) | |
51 | { | |
52 | int i; | |
53 | struct kvm_mmu_page *sp; | |
54 | ||
55 | if (!VALID_PAGE(vcpu->arch.mmu.root_hpa)) | |
56 | return; | |
eb259186 | 57 | |
98224bf1 | 58 | if (vcpu->arch.mmu.root_level == PT64_ROOT_LEVEL) { |
2f4f3372 | 59 | hpa_t root = vcpu->arch.mmu.root_hpa; |
eb259186 | 60 | |
2f4f3372 | 61 | sp = page_header(root); |
eb259186 | 62 | __mmu_spte_walk(vcpu, sp, fn, PT64_ROOT_LEVEL); |
2f4f3372 XG |
63 | return; |
64 | } | |
eb259186 | 65 | |
2f4f3372 XG |
66 | for (i = 0; i < 4; ++i) { |
67 | hpa_t root = vcpu->arch.mmu.pae_root[i]; | |
68 | ||
69 | if (root && VALID_PAGE(root)) { | |
70 | root &= PT64_BASE_ADDR_MASK; | |
71 | sp = page_header(root); | |
eb259186 | 72 | __mmu_spte_walk(vcpu, sp, fn, 2); |
2f4f3372 XG |
73 | } |
74 | } | |
eb259186 | 75 | |
2f4f3372 XG |
76 | return; |
77 | } | |
78 | ||
49edf878 XG |
79 | typedef void (*sp_handler) (struct kvm *kvm, struct kvm_mmu_page *sp); |
80 | ||
81 | static void walk_all_active_sps(struct kvm *kvm, sp_handler fn) | |
82 | { | |
83 | struct kvm_mmu_page *sp; | |
84 | ||
85 | list_for_each_entry(sp, &kvm->arch.active_mmu_pages, link) | |
86 | fn(kvm, sp); | |
87 | } | |
88 | ||
eb259186 | 89 | static void audit_mappings(struct kvm_vcpu *vcpu, u64 *sptep, int level) |
2f4f3372 | 90 | { |
eb259186 XG |
91 | struct kvm_mmu_page *sp; |
92 | gfn_t gfn; | |
93 | pfn_t pfn; | |
94 | hpa_t hpa; | |
2f4f3372 | 95 | |
eb259186 XG |
96 | sp = page_header(__pa(sptep)); |
97 | ||
98 | if (sp->unsync) { | |
99 | if (level != PT_PAGE_TABLE_LEVEL) { | |
38904e12 | 100 | audit_printk("unsync sp: %p level = %d\n", sp, level); |
2f4f3372 XG |
101 | return; |
102 | } | |
103 | ||
eb259186 | 104 | if (*sptep == shadow_notrap_nonpresent_pte) { |
38904e12 | 105 | audit_printk("notrap spte in unsync sp: %p\n", sp); |
2f4f3372 | 106 | return; |
eb259186 XG |
107 | } |
108 | } | |
2f4f3372 | 109 | |
eb259186 | 110 | if (sp->role.direct && *sptep == shadow_notrap_nonpresent_pte) { |
38904e12 | 111 | audit_printk("notrap spte in direct sp: %p\n", sp); |
eb259186 XG |
112 | return; |
113 | } | |
2f4f3372 | 114 | |
eb259186 XG |
115 | if (!is_shadow_present_pte(*sptep) || !is_last_spte(*sptep, level)) |
116 | return; | |
2f4f3372 | 117 | |
eb259186 XG |
118 | gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt); |
119 | pfn = gfn_to_pfn_atomic(vcpu->kvm, gfn); | |
2f4f3372 | 120 | |
eb259186 XG |
121 | if (is_error_pfn(pfn)) { |
122 | kvm_release_pfn_clean(pfn); | |
123 | return; | |
2f4f3372 | 124 | } |
2f4f3372 | 125 | |
eb259186 XG |
126 | hpa = pfn << PAGE_SHIFT; |
127 | if ((*sptep & PT64_BASE_ADDR_MASK) != hpa) | |
38904e12 XG |
128 | audit_printk("levels %d pfn %llx hpa %llx ent %llxn", |
129 | vcpu->arch.mmu.root_level, pfn, hpa, *sptep); | |
2f4f3372 XG |
130 | } |
131 | ||
eb259186 | 132 | static void inspect_spte_has_rmap(struct kvm *kvm, u64 *sptep) |
2f4f3372 XG |
133 | { |
134 | unsigned long *rmapp; | |
135 | struct kvm_mmu_page *rev_sp; | |
136 | gfn_t gfn; | |
137 | ||
138 | ||
139 | rev_sp = page_header(__pa(sptep)); | |
140 | gfn = kvm_mmu_page_get_gfn(rev_sp, sptep - rev_sp->spt); | |
141 | ||
142 | if (!gfn_to_memslot(kvm, gfn)) { | |
143 | if (!printk_ratelimit()) | |
144 | return; | |
38904e12 XG |
145 | audit_printk("no memslot for gfn %llx\n", gfn); |
146 | audit_printk("index %ld of sp (gfn=%llx)\n", | |
147 | (long int)(sptep - rev_sp->spt), rev_sp->gfn); | |
2f4f3372 XG |
148 | dump_stack(); |
149 | return; | |
150 | } | |
151 | ||
152 | rmapp = gfn_to_rmap(kvm, gfn, rev_sp->role.level); | |
153 | if (!*rmapp) { | |
154 | if (!printk_ratelimit()) | |
155 | return; | |
38904e12 | 156 | audit_printk("no rmap for writable spte %llx\n", *sptep); |
2f4f3372 XG |
157 | dump_stack(); |
158 | } | |
159 | } | |
160 | ||
eb259186 | 161 | static void audit_sptes_have_rmaps(struct kvm_vcpu *vcpu, u64 *sptep, int level) |
2f4f3372 | 162 | { |
eb259186 XG |
163 | if (is_shadow_present_pte(*sptep) && is_last_spte(*sptep, level)) |
164 | inspect_spte_has_rmap(vcpu->kvm, sptep); | |
2f4f3372 XG |
165 | } |
166 | ||
6903074c XG |
167 | static void audit_spte_after_sync(struct kvm_vcpu *vcpu, u64 *sptep, int level) |
168 | { | |
169 | struct kvm_mmu_page *sp = page_header(__pa(sptep)); | |
170 | ||
171 | if (audit_point == AUDIT_POST_SYNC && sp->unsync) | |
172 | audit_printk("meet unsync sp(%p) after sync root.\n", sp); | |
173 | } | |
174 | ||
49edf878 | 175 | static void check_mappings_rmap(struct kvm *kvm, struct kvm_mmu_page *sp) |
2f4f3372 | 176 | { |
2f4f3372 XG |
177 | int i; |
178 | ||
49edf878 XG |
179 | if (sp->role.level != PT_PAGE_TABLE_LEVEL) |
180 | return; | |
2f4f3372 | 181 | |
49edf878 XG |
182 | for (i = 0; i < PT64_ENT_PER_PAGE; ++i) { |
183 | if (!is_rmap_spte(sp->spt[i])) | |
2f4f3372 XG |
184 | continue; |
185 | ||
49edf878 | 186 | inspect_spte_has_rmap(kvm, sp->spt + i); |
2f4f3372 | 187 | } |
2f4f3372 XG |
188 | } |
189 | ||
6903074c | 190 | static void audit_write_protection(struct kvm *kvm, struct kvm_mmu_page *sp) |
2f4f3372 | 191 | { |
2f4f3372 XG |
192 | struct kvm_memory_slot *slot; |
193 | unsigned long *rmapp; | |
194 | u64 *spte; | |
195 | ||
49edf878 XG |
196 | if (sp->role.direct || sp->unsync || sp->role.invalid) |
197 | return; | |
2f4f3372 | 198 | |
49edf878 XG |
199 | slot = gfn_to_memslot(kvm, sp->gfn); |
200 | rmapp = &slot->rmap[sp->gfn - slot->base_gfn]; | |
2f4f3372 | 201 | |
49edf878 XG |
202 | spte = rmap_next(kvm, rmapp, NULL); |
203 | while (spte) { | |
204 | if (is_writable_pte(*spte)) | |
38904e12 XG |
205 | audit_printk("shadow page has writable mappings: gfn " |
206 | "%llx role %x\n", sp->gfn, sp->role.word); | |
49edf878 | 207 | spte = rmap_next(kvm, rmapp, spte); |
2f4f3372 XG |
208 | } |
209 | } | |
210 | ||
49edf878 XG |
211 | static void audit_sp(struct kvm *kvm, struct kvm_mmu_page *sp) |
212 | { | |
213 | check_mappings_rmap(kvm, sp); | |
214 | audit_write_protection(kvm, sp); | |
215 | } | |
216 | ||
217 | static void audit_all_active_sps(struct kvm *kvm) | |
218 | { | |
219 | walk_all_active_sps(kvm, audit_sp); | |
220 | } | |
221 | ||
eb259186 XG |
222 | static void audit_spte(struct kvm_vcpu *vcpu, u64 *sptep, int level) |
223 | { | |
224 | audit_sptes_have_rmaps(vcpu, sptep, level); | |
225 | audit_mappings(vcpu, sptep, level); | |
6903074c | 226 | audit_spte_after_sync(vcpu, sptep, level); |
eb259186 XG |
227 | } |
228 | ||
229 | static void audit_vcpu_spte(struct kvm_vcpu *vcpu) | |
230 | { | |
231 | mmu_spte_walk(vcpu, audit_spte); | |
232 | } | |
233 | ||
38904e12 | 234 | static void kvm_mmu_audit(void *ignore, struct kvm_vcpu *vcpu, int point) |
2f4f3372 | 235 | { |
30644b90 XG |
236 | static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10); |
237 | ||
238 | if (!__ratelimit(&ratelimit_state)) | |
239 | return; | |
240 | ||
38904e12 | 241 | audit_point = point; |
49edf878 | 242 | audit_all_active_sps(vcpu->kvm); |
eb259186 | 243 | audit_vcpu_spte(vcpu); |
2f4f3372 XG |
244 | } |
245 | ||
246 | static bool mmu_audit; | |
247 | ||
248 | static void mmu_audit_enable(void) | |
249 | { | |
250 | int ret; | |
251 | ||
252 | if (mmu_audit) | |
253 | return; | |
254 | ||
255 | ret = register_trace_kvm_mmu_audit(kvm_mmu_audit, NULL); | |
256 | WARN_ON(ret); | |
257 | ||
258 | mmu_audit = true; | |
259 | } | |
260 | ||
261 | static void mmu_audit_disable(void) | |
262 | { | |
263 | if (!mmu_audit) | |
264 | return; | |
265 | ||
266 | unregister_trace_kvm_mmu_audit(kvm_mmu_audit, NULL); | |
267 | tracepoint_synchronize_unregister(); | |
268 | mmu_audit = false; | |
269 | } | |
270 | ||
271 | static int mmu_audit_set(const char *val, const struct kernel_param *kp) | |
272 | { | |
273 | int ret; | |
274 | unsigned long enable; | |
275 | ||
276 | ret = strict_strtoul(val, 10, &enable); | |
277 | if (ret < 0) | |
278 | return -EINVAL; | |
279 | ||
280 | switch (enable) { | |
281 | case 0: | |
282 | mmu_audit_disable(); | |
283 | break; | |
284 | case 1: | |
285 | mmu_audit_enable(); | |
286 | break; | |
287 | default: | |
288 | return -EINVAL; | |
289 | } | |
290 | ||
291 | return 0; | |
292 | } | |
293 | ||
294 | static struct kernel_param_ops audit_param_ops = { | |
295 | .set = mmu_audit_set, | |
296 | .get = param_get_bool, | |
297 | }; | |
298 | ||
299 | module_param_cb(mmu_audit, &audit_param_ops, &mmu_audit, 0644); |