5f6223b8bcf734257f3da577be93448e032e4c76
[linux-2.6.git] / arch / x86 / kvm / mmu_audit.c
1 /*
2  * mmu_audit.c:
3  *
4  * Audit code for KVM MMU
5  *
6  * Copyright (C) 2006 Qumranet, Inc.
7  * Copyright 2010 Red Hat, Inc. and/or its affiliates.
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
20 #include <linux/ratelimit.h>
21
22 #define audit_printk(kvm, fmt, args...)         \
23         printk(KERN_ERR "audit: (%s) error: "   \
24                 fmt, audit_point_name[kvm->arch.audit_point], ##args)
25
26 typedef void (*inspect_spte_fn) (struct kvm_vcpu *vcpu, u64 *sptep, int level);
27
28 static void __mmu_spte_walk(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
29                             inspect_spte_fn fn, int level)
30 {
31         int i;
32
33         for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
34                 u64 *ent = sp->spt;
35
36                 fn(vcpu, ent + i, level);
37
38                 if (is_shadow_present_pte(ent[i]) &&
39                       !is_last_spte(ent[i], level)) {
40                         struct kvm_mmu_page *child;
41
42                         child = page_header(ent[i] & PT64_BASE_ADDR_MASK);
43                         __mmu_spte_walk(vcpu, child, fn, level - 1);
44                 }
45         }
46 }
47
48 static void mmu_spte_walk(struct kvm_vcpu *vcpu, inspect_spte_fn fn)
49 {
50         int i;
51         struct kvm_mmu_page *sp;
52
53         if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
54                 return;
55
56         if (vcpu->arch.mmu.root_level == PT64_ROOT_LEVEL) {
57                 hpa_t root = vcpu->arch.mmu.root_hpa;
58
59                 sp = page_header(root);
60                 __mmu_spte_walk(vcpu, sp, fn, PT64_ROOT_LEVEL);
61                 return;
62         }
63
64         for (i = 0; i < 4; ++i) {
65                 hpa_t root = vcpu->arch.mmu.pae_root[i];
66
67                 if (root && VALID_PAGE(root)) {
68                         root &= PT64_BASE_ADDR_MASK;
69                         sp = page_header(root);
70                         __mmu_spte_walk(vcpu, sp, fn, 2);
71                 }
72         }
73
74         return;
75 }
76
77 typedef void (*sp_handler) (struct kvm *kvm, struct kvm_mmu_page *sp);
78
79 static void walk_all_active_sps(struct kvm *kvm, sp_handler fn)
80 {
81         struct kvm_mmu_page *sp;
82
83         list_for_each_entry(sp, &kvm->arch.active_mmu_pages, link)
84                 fn(kvm, sp);
85 }
86
87 static void audit_mappings(struct kvm_vcpu *vcpu, u64 *sptep, int level)
88 {
89         struct kvm_mmu_page *sp;
90         gfn_t gfn;
91         pfn_t pfn;
92         hpa_t hpa;
93
94         sp = page_header(__pa(sptep));
95
96         if (sp->unsync) {
97                 if (level != PT_PAGE_TABLE_LEVEL) {
98                         audit_printk(vcpu->kvm, "unsync sp: %p "
99                                      "level = %d\n", sp, level);
100                         return;
101                 }
102
103                 if (*sptep == shadow_notrap_nonpresent_pte) {
104                         audit_printk(vcpu->kvm, "notrap spte in unsync "
105                                      "sp: %p\n", sp);
106                         return;
107                 }
108         }
109
110         if (sp->role.direct && *sptep == shadow_notrap_nonpresent_pte) {
111                 audit_printk(vcpu->kvm, "notrap spte in direct sp: %p\n",
112                              sp);
113                 return;
114         }
115
116         if (!is_shadow_present_pte(*sptep) || !is_last_spte(*sptep, level))
117                 return;
118
119         gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt);
120         pfn = gfn_to_pfn_atomic(vcpu->kvm, gfn);
121
122         if (is_error_pfn(pfn)) {
123                 kvm_release_pfn_clean(pfn);
124                 return;
125         }
126
127         hpa =  pfn << PAGE_SHIFT;
128         if ((*sptep & PT64_BASE_ADDR_MASK) != hpa)
129                 audit_printk(vcpu->kvm, "levels %d pfn %llx hpa %llx "
130                              "ent %llxn", vcpu->arch.mmu.root_level, pfn,
131                              hpa, *sptep);
132 }
133
134 static void inspect_spte_has_rmap(struct kvm *kvm, u64 *sptep)
135 {
136         unsigned long *rmapp;
137         struct kvm_mmu_page *rev_sp;
138         gfn_t gfn;
139
140
141         rev_sp = page_header(__pa(sptep));
142         gfn = kvm_mmu_page_get_gfn(rev_sp, sptep - rev_sp->spt);
143
144         if (!gfn_to_memslot(kvm, gfn)) {
145                 if (!printk_ratelimit())
146                         return;
147                 audit_printk(kvm, "no memslot for gfn %llx\n", gfn);
148                 audit_printk(kvm, "index %ld of sp (gfn=%llx)\n",
149                        (long int)(sptep - rev_sp->spt), rev_sp->gfn);
150                 dump_stack();
151                 return;
152         }
153
154         rmapp = gfn_to_rmap(kvm, gfn, rev_sp->role.level);
155         if (!*rmapp) {
156                 if (!printk_ratelimit())
157                         return;
158                 audit_printk(kvm, "no rmap for writable spte %llx\n",
159                              *sptep);
160                 dump_stack();
161         }
162 }
163
164 static void audit_sptes_have_rmaps(struct kvm_vcpu *vcpu, u64 *sptep, int level)
165 {
166         if (is_shadow_present_pte(*sptep) && is_last_spte(*sptep, level))
167                 inspect_spte_has_rmap(vcpu->kvm, sptep);
168 }
169
170 static void audit_spte_after_sync(struct kvm_vcpu *vcpu, u64 *sptep, int level)
171 {
172         struct kvm_mmu_page *sp = page_header(__pa(sptep));
173
174         if (vcpu->kvm->arch.audit_point == AUDIT_POST_SYNC && sp->unsync)
175                 audit_printk(vcpu->kvm, "meet unsync sp(%p) after sync "
176                              "root.\n", sp);
177 }
178
179 static void check_mappings_rmap(struct kvm *kvm, struct kvm_mmu_page *sp)
180 {
181         int i;
182
183         if (sp->role.level != PT_PAGE_TABLE_LEVEL)
184                 return;
185
186         for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
187                 if (!is_rmap_spte(sp->spt[i]))
188                         continue;
189
190                 inspect_spte_has_rmap(kvm, sp->spt + i);
191         }
192 }
193
194 static void audit_write_protection(struct kvm *kvm, struct kvm_mmu_page *sp)
195 {
196         struct kvm_memory_slot *slot;
197         unsigned long *rmapp;
198         u64 *spte;
199
200         if (sp->role.direct || sp->unsync || sp->role.invalid)
201                 return;
202
203         slot = gfn_to_memslot(kvm, sp->gfn);
204         rmapp = &slot->rmap[sp->gfn - slot->base_gfn];
205
206         spte = rmap_next(kvm, rmapp, NULL);
207         while (spte) {
208                 if (is_writable_pte(*spte))
209                         audit_printk(kvm, "shadow page has writable "
210                                      "mappings: gfn %llx role %x\n",
211                                      sp->gfn, sp->role.word);
212                 spte = rmap_next(kvm, rmapp, spte);
213         }
214 }
215
216 static void audit_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
217 {
218         check_mappings_rmap(kvm, sp);
219         audit_write_protection(kvm, sp);
220 }
221
222 static void audit_all_active_sps(struct kvm *kvm)
223 {
224         walk_all_active_sps(kvm, audit_sp);
225 }
226
227 static void audit_spte(struct kvm_vcpu *vcpu, u64 *sptep, int level)
228 {
229         audit_sptes_have_rmaps(vcpu, sptep, level);
230         audit_mappings(vcpu, sptep, level);
231         audit_spte_after_sync(vcpu, sptep, level);
232 }
233
234 static void audit_vcpu_spte(struct kvm_vcpu *vcpu)
235 {
236         mmu_spte_walk(vcpu, audit_spte);
237 }
238
239 static void kvm_mmu_audit(void *ignore, struct kvm_vcpu *vcpu, int point)
240 {
241         static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
242
243         if (!__ratelimit(&ratelimit_state))
244                 return;
245
246         vcpu->kvm->arch.audit_point = point;
247         audit_all_active_sps(vcpu->kvm);
248         audit_vcpu_spte(vcpu);
249 }
250
251 static bool mmu_audit;
252
253 static void mmu_audit_enable(void)
254 {
255         int ret;
256
257         if (mmu_audit)
258                 return;
259
260         ret = register_trace_kvm_mmu_audit(kvm_mmu_audit, NULL);
261         WARN_ON(ret);
262
263         mmu_audit = true;
264 }
265
266 static void mmu_audit_disable(void)
267 {
268         if (!mmu_audit)
269                 return;
270
271         unregister_trace_kvm_mmu_audit(kvm_mmu_audit, NULL);
272         tracepoint_synchronize_unregister();
273         mmu_audit = false;
274 }
275
276 static int mmu_audit_set(const char *val, const struct kernel_param *kp)
277 {
278         int ret;
279         unsigned long enable;
280
281         ret = strict_strtoul(val, 10, &enable);
282         if (ret < 0)
283                 return -EINVAL;
284
285         switch (enable) {
286         case 0:
287                 mmu_audit_disable();
288                 break;
289         case 1:
290                 mmu_audit_enable();
291                 break;
292         default:
293                 return -EINVAL;
294         }
295
296         return 0;
297 }
298
299 static struct kernel_param_ops audit_param_ops = {
300         .set = mmu_audit_set,
301         .get = param_get_bool,
302 };
303
304 module_param_cb(mmu_audit, &audit_param_ops, &mmu_audit, 0644);