xref: /linux/arch/x86/kvm/mmu/spte.h (revision 447e140e66fd226350b3ce86cffc965eaae4c856)
1 // SPDX-License-Identifier: GPL-2.0-only
2 
3 #ifndef KVM_X86_MMU_SPTE_H
4 #define KVM_X86_MMU_SPTE_H
5 
6 #include "mmu.h"
7 #include "mmu_internal.h"
8 
9 /*
10  * A MMU present SPTE is backed by actual memory and may or may not be present
11  * in hardware.  E.g. MMIO SPTEs are not considered present.  Use bit 11, as it
12  * is ignored by all flavors of SPTEs and checking a low bit often generates
13  * better code than for a high bit, e.g. 56+.  MMU present checks are pervasive
14  * enough that the improved code generation is noticeable in KVM's footprint.
15  */
16 #define SPTE_MMU_PRESENT_MASK		BIT_ULL(11)
17 
18 /*
19  * TDP SPTES (more specifically, EPT SPTEs) may not have A/D bits, and may also
20  * be restricted to using write-protection (for L2 when CPU dirty logging, i.e.
21  * PML, is enabled).  Use bits 52 and 53 to hold the type of A/D tracking that
22  * is must be employed for a given TDP SPTE.
23  *
24  * Note, the "enabled" mask must be '0', as bits 62:52 are _reserved_ for PAE
25  * paging, including NPT PAE.  This scheme works because legacy shadow paging
26  * is guaranteed to have A/D bits and write-protection is forced only for
27  * TDP with CPU dirty logging (PML).  If NPT ever gains PML-like support, it
28  * must be restricted to 64-bit KVM.
29  */
30 #define SPTE_TDP_AD_SHIFT		52
31 #define SPTE_TDP_AD_MASK		(3ULL << SPTE_TDP_AD_SHIFT)
32 #define SPTE_TDP_AD_ENABLED		(0ULL << SPTE_TDP_AD_SHIFT)
33 #define SPTE_TDP_AD_DISABLED		(1ULL << SPTE_TDP_AD_SHIFT)
34 #define SPTE_TDP_AD_WRPROT_ONLY		(2ULL << SPTE_TDP_AD_SHIFT)
35 static_assert(SPTE_TDP_AD_ENABLED == 0);
36 
37 #ifdef CONFIG_DYNAMIC_PHYSICAL_MASK
38 #define SPTE_BASE_ADDR_MASK (physical_mask & ~(u64)(PAGE_SIZE-1))
39 #else
40 #define SPTE_BASE_ADDR_MASK (((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1))
41 #endif
42 
43 #define SPTE_PERM_MASK (PT_PRESENT_MASK | PT_WRITABLE_MASK | shadow_user_mask \
44 			| shadow_x_mask | shadow_nx_mask | shadow_me_mask)
45 
46 #define ACC_EXEC_MASK    1
47 #define ACC_WRITE_MASK   PT_WRITABLE_MASK
48 #define ACC_USER_MASK    PT_USER_MASK
49 #define ACC_ALL          (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK)
50 
51 /* The mask for the R/X bits in EPT PTEs */
52 #define SPTE_EPT_READABLE_MASK			0x1ull
53 #define SPTE_EPT_EXECUTABLE_MASK		0x4ull
54 
55 #define SPTE_LEVEL_BITS			9
56 #define SPTE_LEVEL_SHIFT(level)		__PT_LEVEL_SHIFT(level, SPTE_LEVEL_BITS)
57 #define SPTE_INDEX(address, level)	__PT_INDEX(address, level, SPTE_LEVEL_BITS)
58 #define SPTE_ENT_PER_PAGE		__PT_ENT_PER_PAGE(SPTE_LEVEL_BITS)
59 
60 /*
61  * The mask/shift to use for saving the original R/X bits when marking the PTE
62  * as not-present for access tracking purposes. We do not save the W bit as the
63  * PTEs being access tracked also need to be dirty tracked, so the W bit will be
64  * restored only when a write is attempted to the page.  This mask obviously
65  * must not overlap the A/D type mask.
66  */
67 #define SHADOW_ACC_TRACK_SAVED_BITS_MASK (SPTE_EPT_READABLE_MASK | \
68 					  SPTE_EPT_EXECUTABLE_MASK)
69 #define SHADOW_ACC_TRACK_SAVED_BITS_SHIFT 54
70 #define SHADOW_ACC_TRACK_SAVED_MASK	(SHADOW_ACC_TRACK_SAVED_BITS_MASK << \
71 					 SHADOW_ACC_TRACK_SAVED_BITS_SHIFT)
72 static_assert(!(SPTE_TDP_AD_MASK & SHADOW_ACC_TRACK_SAVED_MASK));
73 
74 /*
75  * {DEFAULT,EPT}_SPTE_{HOST,MMU}_WRITABLE are used to keep track of why a given
76  * SPTE is write-protected. See is_writable_pte() for details.
77  */
78 
79 /* Bits 9 and 10 are ignored by all non-EPT PTEs. */
80 #define DEFAULT_SPTE_HOST_WRITABLE	BIT_ULL(9)
81 #define DEFAULT_SPTE_MMU_WRITABLE	BIT_ULL(10)
82 
83 /*
84  * Low ignored bits are at a premium for EPT, use high ignored bits, taking care
85  * to not overlap the A/D type mask or the saved access bits of access-tracked
86  * SPTEs when A/D bits are disabled.
87  */
88 #define EPT_SPTE_HOST_WRITABLE		BIT_ULL(57)
89 #define EPT_SPTE_MMU_WRITABLE		BIT_ULL(58)
90 
91 static_assert(!(EPT_SPTE_HOST_WRITABLE & SPTE_TDP_AD_MASK));
92 static_assert(!(EPT_SPTE_MMU_WRITABLE & SPTE_TDP_AD_MASK));
93 static_assert(!(EPT_SPTE_HOST_WRITABLE & SHADOW_ACC_TRACK_SAVED_MASK));
94 static_assert(!(EPT_SPTE_MMU_WRITABLE & SHADOW_ACC_TRACK_SAVED_MASK));
95 
96 /* Defined only to keep the above static asserts readable. */
97 #undef SHADOW_ACC_TRACK_SAVED_MASK
98 
99 /*
100  * Due to limited space in PTEs, the MMIO generation is a 19 bit subset of
101  * the memslots generation and is derived as follows:
102  *
103  * Bits 0-7 of the MMIO generation are propagated to spte bits 3-10
104  * Bits 8-18 of the MMIO generation are propagated to spte bits 52-62
105  *
106  * The KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS flag is intentionally not included in
107  * the MMIO generation number, as doing so would require stealing a bit from
108  * the "real" generation number and thus effectively halve the maximum number
109  * of MMIO generations that can be handled before encountering a wrap (which
110  * requires a full MMU zap).  The flag is instead explicitly queried when
111  * checking for MMIO spte cache hits.
112  */
113 
114 #define MMIO_SPTE_GEN_LOW_START		3
115 #define MMIO_SPTE_GEN_LOW_END		10
116 
117 #define MMIO_SPTE_GEN_HIGH_START	52
118 #define MMIO_SPTE_GEN_HIGH_END		62
119 
120 #define MMIO_SPTE_GEN_LOW_MASK		GENMASK_ULL(MMIO_SPTE_GEN_LOW_END, \
121 						    MMIO_SPTE_GEN_LOW_START)
122 #define MMIO_SPTE_GEN_HIGH_MASK		GENMASK_ULL(MMIO_SPTE_GEN_HIGH_END, \
123 						    MMIO_SPTE_GEN_HIGH_START)
124 static_assert(!(SPTE_MMU_PRESENT_MASK &
125 		(MMIO_SPTE_GEN_LOW_MASK | MMIO_SPTE_GEN_HIGH_MASK)));
126 
127 /*
128  * The SPTE MMIO mask must NOT overlap the MMIO generation bits or the
129  * MMU-present bit.  The generation obviously co-exists with the magic MMIO
130  * mask/value, and MMIO SPTEs are considered !MMU-present.
131  *
132  * The SPTE MMIO mask is allowed to use hardware "present" bits (i.e. all EPT
133  * RWX bits), all physical address bits (legal PA bits are used for "fast" MMIO
134  * and so they're off-limits for generation; additional checks ensure the mask
135  * doesn't overlap legal PA bits), and bit 63 (carved out for future usage).
136  */
137 #define SPTE_MMIO_ALLOWED_MASK (BIT_ULL(63) | GENMASK_ULL(51, 12) | GENMASK_ULL(2, 0))
138 static_assert(!(SPTE_MMIO_ALLOWED_MASK &
139 		(SPTE_MMU_PRESENT_MASK | MMIO_SPTE_GEN_LOW_MASK | MMIO_SPTE_GEN_HIGH_MASK)));
140 
141 #define MMIO_SPTE_GEN_LOW_BITS		(MMIO_SPTE_GEN_LOW_END - MMIO_SPTE_GEN_LOW_START + 1)
142 #define MMIO_SPTE_GEN_HIGH_BITS		(MMIO_SPTE_GEN_HIGH_END - MMIO_SPTE_GEN_HIGH_START + 1)
143 
144 /* remember to adjust the comment above as well if you change these */
145 static_assert(MMIO_SPTE_GEN_LOW_BITS == 8 && MMIO_SPTE_GEN_HIGH_BITS == 11);
146 
147 #define MMIO_SPTE_GEN_LOW_SHIFT		(MMIO_SPTE_GEN_LOW_START - 0)
148 #define MMIO_SPTE_GEN_HIGH_SHIFT	(MMIO_SPTE_GEN_HIGH_START - MMIO_SPTE_GEN_LOW_BITS)
149 
150 #define MMIO_SPTE_GEN_MASK		GENMASK_ULL(MMIO_SPTE_GEN_LOW_BITS + MMIO_SPTE_GEN_HIGH_BITS - 1, 0)
151 
152 /*
153  * Non-present SPTE value needs to set bit 63 for TDX, in order to suppress
154  * #VE and get EPT violations on non-present PTEs.  We can use the
155  * same value also without TDX for both VMX and SVM:
156  *
157  * For SVM NPT, for non-present spte (bit 0 = 0), other bits are ignored.
158  * For VMX EPT, bit 63 is ignored if #VE is disabled. (EPT_VIOLATION_VE=0)
159  *              bit 63 is #VE suppress if #VE is enabled. (EPT_VIOLATION_VE=1)
160  */
161 #ifdef CONFIG_X86_64
162 #define SHADOW_NONPRESENT_VALUE	BIT_ULL(63)
163 static_assert(!(SHADOW_NONPRESENT_VALUE & SPTE_MMU_PRESENT_MASK));
164 #else
165 #define SHADOW_NONPRESENT_VALUE	0ULL
166 #endif
167 
168 extern u64 __read_mostly shadow_host_writable_mask;
169 extern u64 __read_mostly shadow_mmu_writable_mask;
170 extern u64 __read_mostly shadow_nx_mask;
171 extern u64 __read_mostly shadow_x_mask; /* mutual exclusive with nx_mask */
172 extern u64 __read_mostly shadow_user_mask;
173 extern u64 __read_mostly shadow_accessed_mask;
174 extern u64 __read_mostly shadow_dirty_mask;
175 extern u64 __read_mostly shadow_mmio_value;
176 extern u64 __read_mostly shadow_mmio_mask;
177 extern u64 __read_mostly shadow_mmio_access_mask;
178 extern u64 __read_mostly shadow_present_mask;
179 extern u64 __read_mostly shadow_memtype_mask;
180 extern u64 __read_mostly shadow_me_value;
181 extern u64 __read_mostly shadow_me_mask;
182 
183 /*
184  * SPTEs in MMUs without A/D bits are marked with SPTE_TDP_AD_DISABLED;
185  * shadow_acc_track_mask is the set of bits to be cleared in non-accessed
186  * pages.
187  */
188 extern u64 __read_mostly shadow_acc_track_mask;
189 
190 /*
191  * This mask must be set on all non-zero Non-Present or Reserved SPTEs in order
192  * to guard against L1TF attacks.
193  */
194 extern u64 __read_mostly shadow_nonpresent_or_rsvd_mask;
195 
196 /*
197  * The number of high-order 1 bits to use in the mask above.
198  */
199 #define SHADOW_NONPRESENT_OR_RSVD_MASK_LEN 5
200 
201 /*
202  * If a thread running without exclusive control of the MMU lock must perform a
203  * multi-part operation on an SPTE, it can set the SPTE to REMOVED_SPTE as a
204  * non-present intermediate value. Other threads which encounter this value
205  * should not modify the SPTE.
206  *
207  * Use a semi-arbitrary value that doesn't set RWX bits, i.e. is not-present on
208  * both AMD and Intel CPUs, and doesn't set PFN bits, i.e. doesn't create a L1TF
209  * vulnerability.
210  *
211  * Only used by the TDP MMU.
212  */
213 #define REMOVED_SPTE	(SHADOW_NONPRESENT_VALUE | 0x5a0ULL)
214 
215 /* Removed SPTEs must not be misconstrued as shadow present PTEs. */
216 static_assert(!(REMOVED_SPTE & SPTE_MMU_PRESENT_MASK));
217 
218 static inline bool is_removed_spte(u64 spte)
219 {
220 	return spte == REMOVED_SPTE;
221 }
222 
223 /* Get an SPTE's index into its parent's page table (and the spt array). */
224 static inline int spte_index(u64 *sptep)
225 {
226 	return ((unsigned long)sptep / sizeof(*sptep)) & (SPTE_ENT_PER_PAGE - 1);
227 }
228 
229 /*
230  * In some cases, we need to preserve the GFN of a non-present or reserved
231  * SPTE when we usurp the upper five bits of the physical address space to
232  * defend against L1TF, e.g. for MMIO SPTEs.  To preserve the GFN, we'll
233  * shift bits of the GFN that overlap with shadow_nonpresent_or_rsvd_mask
234  * left into the reserved bits, i.e. the GFN in the SPTE will be split into
235  * high and low parts.  This mask covers the lower bits of the GFN.
236  */
237 extern u64 __read_mostly shadow_nonpresent_or_rsvd_lower_gfn_mask;
238 
239 static inline struct kvm_mmu_page *to_shadow_page(hpa_t shadow_page)
240 {
241 	struct page *page = pfn_to_page((shadow_page) >> PAGE_SHIFT);
242 
243 	return (struct kvm_mmu_page *)page_private(page);
244 }
245 
246 static inline struct kvm_mmu_page *spte_to_child_sp(u64 spte)
247 {
248 	return to_shadow_page(spte & SPTE_BASE_ADDR_MASK);
249 }
250 
251 static inline struct kvm_mmu_page *sptep_to_sp(u64 *sptep)
252 {
253 	return to_shadow_page(__pa(sptep));
254 }
255 
256 static inline struct kvm_mmu_page *root_to_sp(hpa_t root)
257 {
258 	if (kvm_mmu_is_dummy_root(root))
259 		return NULL;
260 
261 	/*
262 	 * The "root" may be a special root, e.g. a PAE entry, treat it as a
263 	 * SPTE to ensure any non-PA bits are dropped.
264 	 */
265 	return spte_to_child_sp(root);
266 }
267 
268 static inline bool is_mmio_spte(struct kvm *kvm, u64 spte)
269 {
270 	return (spte & shadow_mmio_mask) == kvm->arch.shadow_mmio_value &&
271 	       likely(enable_mmio_caching);
272 }
273 
274 static inline bool is_shadow_present_pte(u64 pte)
275 {
276 	return !!(pte & SPTE_MMU_PRESENT_MASK);
277 }
278 
279 /*
280  * Returns true if A/D bits are supported in hardware and are enabled by KVM.
281  * When enabled, KVM uses A/D bits for all non-nested MMUs.  Because L1 can
282  * disable A/D bits in EPTP12, SP and SPTE variants are needed to handle the
283  * scenario where KVM is using A/D bits for L1, but not L2.
284  */
285 static inline bool kvm_ad_enabled(void)
286 {
287 	return !!shadow_accessed_mask;
288 }
289 
290 static inline bool sp_ad_disabled(struct kvm_mmu_page *sp)
291 {
292 	return sp->role.ad_disabled;
293 }
294 
295 static inline bool spte_ad_enabled(u64 spte)
296 {
297 	KVM_MMU_WARN_ON(!is_shadow_present_pte(spte));
298 	return (spte & SPTE_TDP_AD_MASK) != SPTE_TDP_AD_DISABLED;
299 }
300 
301 static inline bool spte_ad_need_write_protect(u64 spte)
302 {
303 	KVM_MMU_WARN_ON(!is_shadow_present_pte(spte));
304 	/*
305 	 * This is benign for non-TDP SPTEs as SPTE_TDP_AD_ENABLED is '0',
306 	 * and non-TDP SPTEs will never set these bits.  Optimize for 64-bit
307 	 * TDP and do the A/D type check unconditionally.
308 	 */
309 	return (spte & SPTE_TDP_AD_MASK) != SPTE_TDP_AD_ENABLED;
310 }
311 
312 static inline u64 spte_shadow_accessed_mask(u64 spte)
313 {
314 	KVM_MMU_WARN_ON(!is_shadow_present_pte(spte));
315 	return spte_ad_enabled(spte) ? shadow_accessed_mask : 0;
316 }
317 
318 static inline u64 spte_shadow_dirty_mask(u64 spte)
319 {
320 	KVM_MMU_WARN_ON(!is_shadow_present_pte(spte));
321 	return spte_ad_enabled(spte) ? shadow_dirty_mask : 0;
322 }
323 
324 static inline bool is_access_track_spte(u64 spte)
325 {
326 	return !spte_ad_enabled(spte) && (spte & shadow_acc_track_mask) == 0;
327 }
328 
329 static inline bool is_large_pte(u64 pte)
330 {
331 	return pte & PT_PAGE_SIZE_MASK;
332 }
333 
334 static inline bool is_last_spte(u64 pte, int level)
335 {
336 	return (level == PG_LEVEL_4K) || is_large_pte(pte);
337 }
338 
339 static inline bool is_executable_pte(u64 spte)
340 {
341 	return (spte & (shadow_x_mask | shadow_nx_mask)) == shadow_x_mask;
342 }
343 
344 static inline kvm_pfn_t spte_to_pfn(u64 pte)
345 {
346 	return (pte & SPTE_BASE_ADDR_MASK) >> PAGE_SHIFT;
347 }
348 
349 static inline bool is_accessed_spte(u64 spte)
350 {
351 	u64 accessed_mask = spte_shadow_accessed_mask(spte);
352 
353 	return accessed_mask ? spte & accessed_mask
354 			     : !is_access_track_spte(spte);
355 }
356 
357 static inline bool is_dirty_spte(u64 spte)
358 {
359 	u64 dirty_mask = spte_shadow_dirty_mask(spte);
360 
361 	return dirty_mask ? spte & dirty_mask : spte & PT_WRITABLE_MASK;
362 }
363 
364 static inline u64 get_rsvd_bits(struct rsvd_bits_validate *rsvd_check, u64 pte,
365 				int level)
366 {
367 	int bit7 = (pte >> 7) & 1;
368 
369 	return rsvd_check->rsvd_bits_mask[bit7][level-1];
370 }
371 
372 static inline bool __is_rsvd_bits_set(struct rsvd_bits_validate *rsvd_check,
373 				      u64 pte, int level)
374 {
375 	return pte & get_rsvd_bits(rsvd_check, pte, level);
376 }
377 
378 static inline bool __is_bad_mt_xwr(struct rsvd_bits_validate *rsvd_check,
379 				   u64 pte)
380 {
381 	return rsvd_check->bad_mt_xwr & BIT_ULL(pte & 0x3f);
382 }
383 
384 static __always_inline bool is_rsvd_spte(struct rsvd_bits_validate *rsvd_check,
385 					 u64 spte, int level)
386 {
387 	return __is_bad_mt_xwr(rsvd_check, spte) ||
388 	       __is_rsvd_bits_set(rsvd_check, spte, level);
389 }
390 
391 /*
392  * A shadow-present leaf SPTE may be non-writable for 4 possible reasons:
393  *
394  *  1. To intercept writes for dirty logging. KVM write-protects huge pages
395  *     so that they can be split down into the dirty logging
396  *     granularity (4KiB) whenever the guest writes to them. KVM also
397  *     write-protects 4KiB pages so that writes can be recorded in the dirty log
398  *     (e.g. if not using PML). SPTEs are write-protected for dirty logging
399  *     during the VM-iotcls that enable dirty logging.
400  *
401  *  2. To intercept writes to guest page tables that KVM is shadowing. When a
402  *     guest writes to its page table the corresponding shadow page table will
403  *     be marked "unsync". That way KVM knows which shadow page tables need to
404  *     be updated on the next TLB flush, INVLPG, etc. and which do not.
405  *
406  *  3. To prevent guest writes to read-only memory, such as for memory in a
407  *     read-only memslot or guest memory backed by a read-only VMA. Writes to
408  *     such pages are disallowed entirely.
409  *
410  *  4. To emulate the Accessed bit for SPTEs without A/D bits.  Note, in this
411  *     case, the SPTE is access-protected, not just write-protected!
412  *
413  * For cases #1 and #4, KVM can safely make such SPTEs writable without taking
414  * mmu_lock as capturing the Accessed/Dirty state doesn't require taking it.
415  * To differentiate #1 and #4 from #2 and #3, KVM uses two software-only bits
416  * in the SPTE:
417  *
418  *  shadow_mmu_writable_mask, aka MMU-writable -
419  *    Cleared on SPTEs that KVM is currently write-protecting for shadow paging
420  *    purposes (case 2 above).
421  *
422  *  shadow_host_writable_mask, aka Host-writable -
423  *    Cleared on SPTEs that are not host-writable (case 3 above)
424  *
425  * Note, not all possible combinations of PT_WRITABLE_MASK,
426  * shadow_mmu_writable_mask, and shadow_host_writable_mask are valid. A given
427  * SPTE can be in only one of the following states, which map to the
428  * aforementioned 3 cases:
429  *
430  *   shadow_host_writable_mask | shadow_mmu_writable_mask | PT_WRITABLE_MASK
431  *   ------------------------- | ------------------------ | ----------------
432  *   1                         | 1                        | 1       (writable)
433  *   1                         | 1                        | 0       (case 1)
434  *   1                         | 0                        | 0       (case 2)
435  *   0                         | 0                        | 0       (case 3)
436  *
437  * The valid combinations of these bits are checked by
438  * check_spte_writable_invariants() whenever an SPTE is modified.
439  *
440  * Clearing the MMU-writable bit is always done under the MMU lock and always
441  * accompanied by a TLB flush before dropping the lock to avoid corrupting the
442  * shadow page tables between vCPUs. Write-protecting an SPTE for dirty logging
443  * (which does not clear the MMU-writable bit), does not flush TLBs before
444  * dropping the lock, as it only needs to synchronize guest writes with the
445  * dirty bitmap. Similarly, making the SPTE inaccessible (and non-writable) for
446  * access-tracking via the clear_young() MMU notifier also does not flush TLBs.
447  *
448  * So, there is the problem: clearing the MMU-writable bit can encounter a
449  * write-protected SPTE while CPUs still have writable mappings for that SPTE
450  * cached in their TLB. To address this, KVM always flushes TLBs when
451  * write-protecting SPTEs if the MMU-writable bit is set on the old SPTE.
452  *
453  * The Host-writable bit is not modified on present SPTEs, it is only set or
454  * cleared when an SPTE is first faulted in from non-present and then remains
455  * immutable.
456  */
457 static inline bool is_writable_pte(unsigned long pte)
458 {
459 	return pte & PT_WRITABLE_MASK;
460 }
461 
462 /* Note: spte must be a shadow-present leaf SPTE. */
463 static inline void check_spte_writable_invariants(u64 spte)
464 {
465 	if (spte & shadow_mmu_writable_mask)
466 		WARN_ONCE(!(spte & shadow_host_writable_mask),
467 			  KBUILD_MODNAME ": MMU-writable SPTE is not Host-writable: %llx",
468 			  spte);
469 	else
470 		WARN_ONCE(is_writable_pte(spte),
471 			  KBUILD_MODNAME ": Writable SPTE is not MMU-writable: %llx", spte);
472 }
473 
474 static inline bool is_mmu_writable_spte(u64 spte)
475 {
476 	return spte & shadow_mmu_writable_mask;
477 }
478 
479 static inline u64 get_mmio_spte_generation(u64 spte)
480 {
481 	u64 gen;
482 
483 	gen = (spte & MMIO_SPTE_GEN_LOW_MASK) >> MMIO_SPTE_GEN_LOW_SHIFT;
484 	gen |= (spte & MMIO_SPTE_GEN_HIGH_MASK) >> MMIO_SPTE_GEN_HIGH_SHIFT;
485 	return gen;
486 }
487 
488 bool spte_has_volatile_bits(u64 spte);
489 
490 bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
491 	       const struct kvm_memory_slot *slot,
492 	       unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn,
493 	       u64 old_spte, bool prefetch, bool can_unsync,
494 	       bool host_writable, u64 *new_spte);
495 u64 make_huge_page_split_spte(struct kvm *kvm, u64 huge_spte,
496 		      	      union kvm_mmu_page_role role, int index);
497 u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled);
498 u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access);
499 u64 mark_spte_for_access_track(u64 spte);
500 
501 /* Restore an acc-track PTE back to a regular PTE */
502 static inline u64 restore_acc_track_spte(u64 spte)
503 {
504 	u64 saved_bits = (spte >> SHADOW_ACC_TRACK_SAVED_BITS_SHIFT)
505 			 & SHADOW_ACC_TRACK_SAVED_BITS_MASK;
506 
507 	spte &= ~shadow_acc_track_mask;
508 	spte &= ~(SHADOW_ACC_TRACK_SAVED_BITS_MASK <<
509 		  SHADOW_ACC_TRACK_SAVED_BITS_SHIFT);
510 	spte |= saved_bits;
511 
512 	return spte;
513 }
514 
515 void __init kvm_mmu_spte_module_init(void);
516 void kvm_mmu_reset_all_pte_masks(void);
517 
518 #endif
519