1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __KVM_X86_MMU_INTERNAL_H
3 #define __KVM_X86_MMU_INTERNAL_H
4
5 #include <linux/types.h>
6 #include <linux/kvm_host.h>
7 #include <asm/kvm_host.h>
8
9 #ifdef CONFIG_KVM_PROVE_MMU
10 #define KVM_MMU_WARN_ON(x) WARN_ON_ONCE(x)
11 #else
12 #define KVM_MMU_WARN_ON(x) BUILD_BUG_ON_INVALID(x)
13 #endif
14
15 /* Page table builder macros common to shadow (host) PTEs and guest PTEs. */
16 #define __PT_LEVEL_SHIFT(level, bits_per_level) \
17 (PAGE_SHIFT + ((level) - 1) * (bits_per_level))
18 #define __PT_INDEX(address, level, bits_per_level) \
19 (((address) >> __PT_LEVEL_SHIFT(level, bits_per_level)) & ((1 << (bits_per_level)) - 1))
20
21 #define __PT_LVL_ADDR_MASK(base_addr_mask, level, bits_per_level) \
22 ((base_addr_mask) & ~((1ULL << (PAGE_SHIFT + (((level) - 1) * (bits_per_level)))) - 1))
23
24 #define __PT_LVL_OFFSET_MASK(base_addr_mask, level, bits_per_level) \
25 ((base_addr_mask) & ((1ULL << (PAGE_SHIFT + (((level) - 1) * (bits_per_level)))) - 1))
26
27 #define __PT_ENT_PER_PAGE(bits_per_level) (1 << (bits_per_level))
28
29 /*
30 * Unlike regular MMU roots, PAE "roots", a.k.a. PDPTEs/PDPTRs, have a PRESENT
31 * bit, and thus are guaranteed to be non-zero when valid. And, when a guest
32 * PDPTR is !PRESENT, its corresponding PAE root cannot be set to INVALID_PAGE,
33 * as the CPU would treat that as PRESENT PDPTR with reserved bits set. Use
34 * '0' instead of INVALID_PAGE to indicate an invalid PAE root.
35 */
36 #define INVALID_PAE_ROOT 0
37 #define IS_VALID_PAE_ROOT(x) (!!(x))
38
kvm_mmu_get_dummy_root(void)39 static inline hpa_t kvm_mmu_get_dummy_root(void)
40 {
41 return my_zero_pfn(0) << PAGE_SHIFT;
42 }
43
kvm_mmu_is_dummy_root(hpa_t shadow_page)44 static inline bool kvm_mmu_is_dummy_root(hpa_t shadow_page)
45 {
46 return is_zero_pfn(shadow_page >> PAGE_SHIFT);
47 }
48
49 typedef u64 __rcu *tdp_ptep_t;
50
51 struct kvm_mmu_page {
52 /*
53 * Note, "link" through "spt" fit in a single 64 byte cache line on
54 * 64-bit kernels, keep it that way unless there's a reason not to.
55 */
56 struct list_head link;
57 struct hlist_node hash_link;
58
59 bool tdp_mmu_page;
60 bool unsync;
61 union {
62 u8 mmu_valid_gen;
63
64 /* Only accessed under slots_lock. */
65 bool tdp_mmu_scheduled_root_to_zap;
66 };
67
68 /*
69 * The shadow page can't be replaced by an equivalent huge page
70 * because it is being used to map an executable page in the guest
71 * and the NX huge page mitigation is enabled.
72 */
73 bool nx_huge_page_disallowed;
74
75 /*
76 * The following two entries are used to key the shadow page in the
77 * hash table.
78 */
79 union kvm_mmu_page_role role;
80 gfn_t gfn;
81
82 u64 *spt;
83
84 /*
85 * Stores the result of the guest translation being shadowed by each
86 * SPTE. KVM shadows two types of guest translations: nGPA -> GPA
87 * (shadow EPT/NPT) and GVA -> GPA (traditional shadow paging). In both
88 * cases the result of the translation is a GPA and a set of access
89 * constraints.
90 *
91 * The GFN is stored in the upper bits (PAGE_SHIFT) and the shadowed
92 * access permissions are stored in the lower bits. Note, for
93 * convenience and uniformity across guests, the access permissions are
94 * stored in KVM format (e.g. ACC_EXEC_MASK) not the raw guest format.
95 */
96 u64 *shadowed_translation;
97
98 /* Currently serving as active root */
99 union {
100 int root_count;
101 refcount_t tdp_mmu_root_count;
102 };
103 unsigned int unsync_children;
104 union {
105 struct kvm_rmap_head parent_ptes; /* rmap pointers to parent sptes */
106 tdp_ptep_t ptep;
107 };
108 DECLARE_BITMAP(unsync_child_bitmap, 512);
109
110 /*
111 * Tracks shadow pages that, if zapped, would allow KVM to create an NX
112 * huge page. A shadow page will have nx_huge_page_disallowed set but
113 * not be on the list if a huge page is disallowed for other reasons,
114 * e.g. because KVM is shadowing a PTE at the same gfn, the memslot
115 * isn't properly aligned, etc...
116 */
117 struct list_head possible_nx_huge_page_link;
118 #ifdef CONFIG_X86_32
119 /*
120 * Used out of the mmu-lock to avoid reading spte values while an
121 * update is in progress; see the comments in __get_spte_lockless().
122 */
123 int clear_spte_count;
124 #endif
125
126 /* Number of writes since the last time traversal visited this page. */
127 atomic_t write_flooding_count;
128
129 #ifdef CONFIG_X86_64
130 /* Used for freeing the page asynchronously if it is a TDP MMU page. */
131 struct rcu_head rcu_head;
132 #endif
133 };
134
135 extern struct kmem_cache *mmu_page_header_cache;
136
kvm_mmu_role_as_id(union kvm_mmu_page_role role)137 static inline int kvm_mmu_role_as_id(union kvm_mmu_page_role role)
138 {
139 return role.smm ? 1 : 0;
140 }
141
kvm_mmu_page_as_id(struct kvm_mmu_page * sp)142 static inline int kvm_mmu_page_as_id(struct kvm_mmu_page *sp)
143 {
144 return kvm_mmu_role_as_id(sp->role);
145 }
146
kvm_mmu_page_ad_need_write_protect(struct kvm_mmu_page * sp)147 static inline bool kvm_mmu_page_ad_need_write_protect(struct kvm_mmu_page *sp)
148 {
149 /*
150 * When using the EPT page-modification log, the GPAs in the CPU dirty
151 * log would come from L2 rather than L1. Therefore, we need to rely
152 * on write protection to record dirty pages, which bypasses PML, since
153 * writes now result in a vmexit. Note, the check on CPU dirty logging
154 * being enabled is mandatory as the bits used to denote WP-only SPTEs
155 * are reserved for PAE paging (32-bit KVM).
156 */
157 return kvm_x86_ops.cpu_dirty_log_size && sp->role.guest_mode;
158 }
159
gfn_round_for_level(gfn_t gfn,int level)160 static inline gfn_t gfn_round_for_level(gfn_t gfn, int level)
161 {
162 return gfn & -KVM_PAGES_PER_HPAGE(level);
163 }
164
165 int mmu_try_to_unsync_pages(struct kvm *kvm, const struct kvm_memory_slot *slot,
166 gfn_t gfn, bool can_unsync, bool prefetch);
167
168 void kvm_mmu_gfn_disallow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn);
169 void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn);
170 bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
171 struct kvm_memory_slot *slot, u64 gfn,
172 int min_level);
173
174 /* Flush the given page (huge or not) of guest memory. */
kvm_flush_remote_tlbs_gfn(struct kvm * kvm,gfn_t gfn,int level)175 static inline void kvm_flush_remote_tlbs_gfn(struct kvm *kvm, gfn_t gfn, int level)
176 {
177 kvm_flush_remote_tlbs_range(kvm, gfn_round_for_level(gfn, level),
178 KVM_PAGES_PER_HPAGE(level));
179 }
180
181 unsigned int pte_list_count(struct kvm_rmap_head *rmap_head);
182
183 extern int nx_huge_pages;
is_nx_huge_page_enabled(struct kvm * kvm)184 static inline bool is_nx_huge_page_enabled(struct kvm *kvm)
185 {
186 return READ_ONCE(nx_huge_pages) && !kvm->arch.disable_nx_huge_pages;
187 }
188
189 struct kvm_page_fault {
190 /* arguments to kvm_mmu_do_page_fault. */
191 const gpa_t addr;
192 const u32 error_code;
193 const bool prefetch;
194
195 /* Derived from error_code. */
196 const bool exec;
197 const bool write;
198 const bool present;
199 const bool rsvd;
200 const bool user;
201
202 /* Derived from mmu and global state. */
203 const bool is_tdp;
204 const bool nx_huge_page_workaround_enabled;
205
206 /*
207 * Whether a >4KB mapping can be created or is forbidden due to NX
208 * hugepages.
209 */
210 bool huge_page_disallowed;
211
212 /*
213 * Maximum page size that can be created for this fault; input to
214 * FNAME(fetch), direct_map() and kvm_tdp_mmu_map().
215 */
216 u8 max_level;
217
218 /*
219 * Page size that can be created based on the max_level and the
220 * page size used by the host mapping.
221 */
222 u8 req_level;
223
224 /*
225 * Page size that will be created based on the req_level and
226 * huge_page_disallowed.
227 */
228 u8 goal_level;
229
230 /* Shifted addr, or result of guest page table walk if addr is a gva. */
231 gfn_t gfn;
232
233 /* The memslot containing gfn. May be NULL. */
234 struct kvm_memory_slot *slot;
235
236 /* Outputs of kvm_faultin_pfn. */
237 unsigned long mmu_seq;
238 kvm_pfn_t pfn;
239 hva_t hva;
240 bool map_writable;
241
242 /*
243 * Indicates the guest is trying to write a gfn that contains one or
244 * more of the PTEs used to translate the write itself, i.e. the access
245 * is changing its own translation in the guest page tables.
246 */
247 bool write_fault_to_shadow_pgtable;
248 };
249
250 int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault);
251
252 /*
253 * Return values of handle_mmio_page_fault(), mmu.page_fault(), fast_page_fault(),
254 * and of course kvm_mmu_do_page_fault().
255 *
256 * RET_PF_CONTINUE: So far, so good, keep handling the page fault.
257 * RET_PF_RETRY: let CPU fault again on the address.
258 * RET_PF_EMULATE: mmio page fault, emulate the instruction directly.
259 * RET_PF_INVALID: the spte is invalid, let the real page fault path update it.
260 * RET_PF_FIXED: The faulting entry has been fixed.
261 * RET_PF_SPURIOUS: The faulting entry was already fixed, e.g. by another vCPU.
262 *
263 * Any names added to this enum should be exported to userspace for use in
264 * tracepoints via TRACE_DEFINE_ENUM() in mmutrace.h
265 *
266 * Note, all values must be greater than or equal to zero so as not to encroach
267 * on -errno return values. Somewhat arbitrarily use '0' for CONTINUE, which
268 * will allow for efficient machine code when checking for CONTINUE, e.g.
269 * "TEST %rax, %rax, JNZ", as all "stop!" values are non-zero.
270 */
271 enum {
272 RET_PF_CONTINUE = 0,
273 RET_PF_RETRY,
274 RET_PF_EMULATE,
275 RET_PF_INVALID,
276 RET_PF_FIXED,
277 RET_PF_SPURIOUS,
278 };
279
kvm_mmu_do_page_fault(struct kvm_vcpu * vcpu,gpa_t cr2_or_gpa,u32 err,bool prefetch,int * emulation_type)280 static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
281 u32 err, bool prefetch, int *emulation_type)
282 {
283 struct kvm_page_fault fault = {
284 .addr = cr2_or_gpa,
285 .error_code = err,
286 .exec = err & PFERR_FETCH_MASK,
287 .write = err & PFERR_WRITE_MASK,
288 .present = err & PFERR_PRESENT_MASK,
289 .rsvd = err & PFERR_RSVD_MASK,
290 .user = err & PFERR_USER_MASK,
291 .prefetch = prefetch,
292 .is_tdp = likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault),
293 .nx_huge_page_workaround_enabled =
294 is_nx_huge_page_enabled(vcpu->kvm),
295
296 .max_level = KVM_MAX_HUGEPAGE_LEVEL,
297 .req_level = PG_LEVEL_4K,
298 .goal_level = PG_LEVEL_4K,
299 };
300 int r;
301
302 if (vcpu->arch.mmu->root_role.direct) {
303 fault.gfn = fault.addr >> PAGE_SHIFT;
304 fault.slot = kvm_vcpu_gfn_to_memslot(vcpu, fault.gfn);
305 }
306
307 /*
308 * Async #PF "faults", a.k.a. prefetch faults, are not faults from the
309 * guest perspective and have already been counted at the time of the
310 * original fault.
311 */
312 if (!prefetch)
313 vcpu->stat.pf_taken++;
314
315 if (IS_ENABLED(CONFIG_RETPOLINE) && fault.is_tdp)
316 r = kvm_tdp_page_fault(vcpu, &fault);
317 else
318 r = vcpu->arch.mmu->page_fault(vcpu, &fault);
319
320 if (fault.write_fault_to_shadow_pgtable && emulation_type)
321 *emulation_type |= EMULTYPE_WRITE_PF_TO_SP;
322
323 /*
324 * Similar to above, prefetch faults aren't truly spurious, and the
325 * async #PF path doesn't do emulation. Do count faults that are fixed
326 * by the async #PF handler though, otherwise they'll never be counted.
327 */
328 if (r == RET_PF_FIXED)
329 vcpu->stat.pf_fixed++;
330 else if (prefetch)
331 ;
332 else if (r == RET_PF_EMULATE)
333 vcpu->stat.pf_emulate++;
334 else if (r == RET_PF_SPURIOUS)
335 vcpu->stat.pf_spurious++;
336 return r;
337 }
338
339 int kvm_mmu_max_mapping_level(struct kvm *kvm,
340 const struct kvm_memory_slot *slot, gfn_t gfn,
341 int max_level);
342 void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault);
343 void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_level);
344
345 void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc);
346
347 void track_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp);
348 void untrack_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp);
349
350 #endif /* __KVM_X86_MMU_INTERNAL_H */
351
