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 bool lpage_disallowed; /* Can't be replaced by an equiv large page */
61
62 /*
63 * The following two entries are used to key the shadow page in the
64 * hash table.
65 */
66 union kvm_mmu_page_role role;
67 gfn_t gfn;
68
69 u64 *spt;
70
71 /*
72 * Stores the result of the guest translation being shadowed by each
73 * SPTE. KVM shadows two types of guest translations: nGPA -> GPA
74 * (shadow EPT/NPT) and GVA -> GPA (traditional shadow paging). In both
75 * cases the result of the translation is a GPA and a set of access
76 * constraints.
77 *
78 * The GFN is stored in the upper bits (PAGE_SHIFT) and the shadowed
79 * access permissions are stored in the lower bits. Note, for
80 * convenience and uniformity across guests, the access permissions are
81 * stored in KVM format (e.g. ACC_EXEC_MASK) not the raw guest format.
82 */
83 u64 *shadowed_translation;
84
85 /* Currently serving as active root */
86 union {
87 int root_count;
88 refcount_t tdp_mmu_root_count;
89 };
90 unsigned int unsync_children;
91 union {
92 struct kvm_rmap_head parent_ptes; /* rmap pointers to parent sptes */
93 tdp_ptep_t ptep;
94 };
95 union {
96 DECLARE_BITMAP(unsync_child_bitmap, 512);
97 struct {
98 struct work_struct tdp_mmu_async_work;
99 void *tdp_mmu_async_data;
100 };
101 };
102
103 struct list_head lpage_disallowed_link;
104 #ifdef CONFIG_X86_32
105 /*
106 * Used out of the mmu-lock to avoid reading spte values while an
107 * update is in progress; see the comments in __get_spte_lockless().
108 */
109 int clear_spte_count;
110 #endif
111
112 /* Number of writes since the last time traversal visited this page. */
113 atomic_t write_flooding_count;
114
115 #ifdef CONFIG_X86_64
116 /* Used for freeing the page asynchronously if it is a TDP MMU page. */
117 struct rcu_head rcu_head;
118 #endif
119 };
120
121 extern struct kmem_cache *mmu_page_header_cache;
122
to_shadow_page(hpa_t shadow_page)123 static inline struct kvm_mmu_page *to_shadow_page(hpa_t shadow_page)
124 {
125 struct page *page = pfn_to_page(shadow_page >> PAGE_SHIFT);
126
127 return (struct kvm_mmu_page *)page_private(page);
128 }
129
sptep_to_sp(u64 * sptep)130 static inline struct kvm_mmu_page *sptep_to_sp(u64 *sptep)
131 {
132 return to_shadow_page(__pa(sptep));
133 }
134
kvm_mmu_role_as_id(union kvm_mmu_page_role role)135 static inline int kvm_mmu_role_as_id(union kvm_mmu_page_role role)
136 {
137 return role.smm ? 1 : 0;
138 }
139
kvm_mmu_page_as_id(struct kvm_mmu_page * sp)140 static inline int kvm_mmu_page_as_id(struct kvm_mmu_page *sp)
141 {
142 return kvm_mmu_role_as_id(sp->role);
143 }
144
kvm_mmu_page_ad_need_write_protect(struct kvm_mmu_page * sp)145 static inline bool kvm_mmu_page_ad_need_write_protect(struct kvm_mmu_page *sp)
146 {
147 /*
148 * When using the EPT page-modification log, the GPAs in the CPU dirty
149 * log would come from L2 rather than L1. Therefore, we need to rely
150 * on write protection to record dirty pages, which bypasses PML, since
151 * writes now result in a vmexit. Note, the check on CPU dirty logging
152 * being enabled is mandatory as the bits used to denote WP-only SPTEs
153 * are reserved for PAE paging (32-bit KVM).
154 */
155 return kvm_x86_ops.cpu_dirty_log_size && sp->role.guest_mode;
156 }
157
158 int mmu_try_to_unsync_pages(struct kvm *kvm, const struct kvm_memory_slot *slot,
159 gfn_t gfn, bool can_unsync, bool prefetch);
160
161 void kvm_mmu_gfn_disallow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn);
162 void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn);
163 bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
164 struct kvm_memory_slot *slot, u64 gfn,
165 int min_level);
166 void kvm_flush_remote_tlbs_with_address(struct kvm *kvm,
167 u64 start_gfn, u64 pages);
168 unsigned int pte_list_count(struct kvm_rmap_head *rmap_head);
169
170 extern int nx_huge_pages;
is_nx_huge_page_enabled(struct kvm * kvm)171 static inline bool is_nx_huge_page_enabled(struct kvm *kvm)
172 {
173 return READ_ONCE(nx_huge_pages) && !kvm->arch.disable_nx_huge_pages;
174 }
175
176 struct kvm_page_fault {
177 /* arguments to kvm_mmu_do_page_fault. */
178 const gpa_t addr;
179 const u32 error_code;
180 const bool prefetch;
181
182 /* Derived from error_code. */
183 const bool exec;
184 const bool write;
185 const bool present;
186 const bool rsvd;
187 const bool user;
188
189 /* Derived from mmu and global state. */
190 const bool is_tdp;
191 const bool nx_huge_page_workaround_enabled;
192
193 /*
194 * Whether a >4KB mapping can be created or is forbidden due to NX
195 * hugepages.
196 */
197 bool huge_page_disallowed;
198
199 /*
200 * Maximum page size that can be created for this fault; input to
201 * FNAME(fetch), __direct_map and kvm_tdp_mmu_map.
202 */
203 u8 max_level;
204
205 /*
206 * Page size that can be created based on the max_level and the
207 * page size used by the host mapping.
208 */
209 u8 req_level;
210
211 /*
212 * Page size that will be created based on the req_level and
213 * huge_page_disallowed.
214 */
215 u8 goal_level;
216
217 /* Shifted addr, or result of guest page table walk if addr is a gva. */
218 gfn_t gfn;
219
220 /* The memslot containing gfn. May be NULL. */
221 struct kvm_memory_slot *slot;
222
223 /* Outputs of kvm_faultin_pfn. */
224 kvm_pfn_t pfn;
225 hva_t hva;
226 bool map_writable;
227 };
228
229 int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault);
230
231 /*
232 * Return values of handle_mmio_page_fault(), mmu.page_fault(), fast_page_fault(),
233 * and of course kvm_mmu_do_page_fault().
234 *
235 * RET_PF_CONTINUE: So far, so good, keep handling the page fault.
236 * RET_PF_RETRY: let CPU fault again on the address.
237 * RET_PF_EMULATE: mmio page fault, emulate the instruction directly.
238 * RET_PF_INVALID: the spte is invalid, let the real page fault path update it.
239 * RET_PF_FIXED: The faulting entry has been fixed.
240 * RET_PF_SPURIOUS: The faulting entry was already fixed, e.g. by another vCPU.
241 *
242 * Any names added to this enum should be exported to userspace for use in
243 * tracepoints via TRACE_DEFINE_ENUM() in mmutrace.h
244 *
245 * Note, all values must be greater than or equal to zero so as not to encroach
246 * on -errno return values. Somewhat arbitrarily use '0' for CONTINUE, which
247 * will allow for efficient machine code when checking for CONTINUE, e.g.
248 * "TEST %rax, %rax, JNZ", as all "stop!" values are non-zero.
249 */
250 enum {
251 RET_PF_CONTINUE = 0,
252 RET_PF_RETRY,
253 RET_PF_EMULATE,
254 RET_PF_INVALID,
255 RET_PF_FIXED,
256 RET_PF_SPURIOUS,
257 };
258
kvm_mmu_do_page_fault(struct kvm_vcpu * vcpu,gpa_t cr2_or_gpa,u32 err,bool prefetch)259 static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
260 u32 err, bool prefetch)
261 {
262 struct kvm_page_fault fault = {
263 .addr = cr2_or_gpa,
264 .error_code = err,
265 .exec = err & PFERR_FETCH_MASK,
266 .write = err & PFERR_WRITE_MASK,
267 .present = err & PFERR_PRESENT_MASK,
268 .rsvd = err & PFERR_RSVD_MASK,
269 .user = err & PFERR_USER_MASK,
270 .prefetch = prefetch,
271 .is_tdp = likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault),
272 .nx_huge_page_workaround_enabled =
273 is_nx_huge_page_enabled(vcpu->kvm),
274
275 .max_level = KVM_MAX_HUGEPAGE_LEVEL,
276 .req_level = PG_LEVEL_4K,
277 .goal_level = PG_LEVEL_4K,
278 };
279 int r;
280
281 /*
282 * Async #PF "faults", a.k.a. prefetch faults, are not faults from the
283 * guest perspective and have already been counted at the time of the
284 * original fault.
285 */
286 if (!prefetch)
287 vcpu->stat.pf_taken++;
288
289 if (IS_ENABLED(CONFIG_RETPOLINE) && fault.is_tdp)
290 r = kvm_tdp_page_fault(vcpu, &fault);
291 else
292 r = vcpu->arch.mmu->page_fault(vcpu, &fault);
293
294 /*
295 * Similar to above, prefetch faults aren't truly spurious, and the
296 * async #PF path doesn't do emulation. Do count faults that are fixed
297 * by the async #PF handler though, otherwise they'll never be counted.
298 */
299 if (r == RET_PF_FIXED)
300 vcpu->stat.pf_fixed++;
301 else if (prefetch)
302 ;
303 else if (r == RET_PF_EMULATE)
304 vcpu->stat.pf_emulate++;
305 else if (r == RET_PF_SPURIOUS)
306 vcpu->stat.pf_spurious++;
307 return r;
308 }
309
310 int kvm_mmu_max_mapping_level(struct kvm *kvm,
311 const struct kvm_memory_slot *slot, gfn_t gfn,
312 int max_level);
313 void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault);
314 void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_level);
315
316 void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc);
317
318 void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp);
319 void unaccount_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp);
320
321 #endif /* __KVM_X86_MMU_INTERNAL_H */
322