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