xref: /linux/arch/x86/kvm/mmu/spte.h (revision c532de5a67a70f8533d495f8f2aaa9a0491c3ad0)
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 <asm/vmx.h>
7 
8 #include "mmu.h"
9 #include "mmu_internal.h"
10 
11 /*
12  * A MMU present SPTE is backed by actual memory and may or may not be present
13  * in hardware.  E.g. MMIO SPTEs are not considered present.  Use bit 11, as it
14  * is ignored by all flavors of SPTEs and checking a low bit often generates
15  * better code than for a high bit, e.g. 56+.  MMU present checks are pervasive
16  * enough that the improved code generation is noticeable in KVM's footprint.
17  */
18 #define SPTE_MMU_PRESENT_MASK		BIT_ULL(11)
19 
20 /*
21  * TDP SPTES (more specifically, EPT SPTEs) may not have A/D bits, and may also
22  * be restricted to using write-protection (for L2 when CPU dirty logging, i.e.
23  * PML, is enabled).  Use bits 52 and 53 to hold the type of A/D tracking that
24  * is must be employed for a given TDP SPTE.
25  *
26  * Note, the "enabled" mask must be '0', as bits 62:52 are _reserved_ for PAE
27  * paging, including NPT PAE.  This scheme works because legacy shadow paging
28  * is guaranteed to have A/D bits and write-protection is forced only for
29  * TDP with CPU dirty logging (PML).  If NPT ever gains PML-like support, it
30  * must be restricted to 64-bit KVM.
31  */
32 #define SPTE_TDP_AD_SHIFT		52
33 #define SPTE_TDP_AD_MASK		(3ULL << SPTE_TDP_AD_SHIFT)
34 #define SPTE_TDP_AD_ENABLED		(0ULL << SPTE_TDP_AD_SHIFT)
35 #define SPTE_TDP_AD_DISABLED		(1ULL << SPTE_TDP_AD_SHIFT)
36 #define SPTE_TDP_AD_WRPROT_ONLY		(2ULL << SPTE_TDP_AD_SHIFT)
37 static_assert(SPTE_TDP_AD_ENABLED == 0);
38 
39 #ifdef CONFIG_DYNAMIC_PHYSICAL_MASK
40 #define SPTE_BASE_ADDR_MASK (physical_mask & ~(u64)(PAGE_SIZE-1))
41 #else
42 #define SPTE_BASE_ADDR_MASK (((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1))
43 #endif
44 
45 #define SPTE_PERM_MASK (PT_PRESENT_MASK | PT_WRITABLE_MASK | shadow_user_mask \
46 			| shadow_x_mask | shadow_nx_mask | shadow_me_mask)
47 
48 #define ACC_EXEC_MASK    1
49 #define ACC_WRITE_MASK   PT_WRITABLE_MASK
50 #define ACC_USER_MASK    PT_USER_MASK
51 #define ACC_ALL          (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK)
52 
53 /* The mask for the R/X bits in EPT PTEs */
54 #define SPTE_EPT_READABLE_MASK			0x1ull
55 #define SPTE_EPT_EXECUTABLE_MASK		0x4ull
56 
57 #define SPTE_LEVEL_BITS			9
58 #define SPTE_LEVEL_SHIFT(level)		__PT_LEVEL_SHIFT(level, SPTE_LEVEL_BITS)
59 #define SPTE_INDEX(address, level)	__PT_INDEX(address, level, SPTE_LEVEL_BITS)
60 #define SPTE_ENT_PER_PAGE		__PT_ENT_PER_PAGE(SPTE_LEVEL_BITS)
61 
62 /*
63  * The mask/shift to use for saving the original R/X bits when marking the PTE
64  * as not-present for access tracking purposes. We do not save the W bit as the
65  * PTEs being access tracked also need to be dirty tracked, so the W bit will be
66  * restored only when a write is attempted to the page.  This mask obviously
67  * must not overlap the A/D type mask.
68  */
69 #define SHADOW_ACC_TRACK_SAVED_BITS_MASK (SPTE_EPT_READABLE_MASK | \
70 					  SPTE_EPT_EXECUTABLE_MASK)
71 #define SHADOW_ACC_TRACK_SAVED_BITS_SHIFT 54
72 #define SHADOW_ACC_TRACK_SAVED_MASK	(SHADOW_ACC_TRACK_SAVED_BITS_MASK << \
73 					 SHADOW_ACC_TRACK_SAVED_BITS_SHIFT)
74 static_assert(!(SPTE_TDP_AD_MASK & SHADOW_ACC_TRACK_SAVED_MASK));
75 
76 /*
77  * {DEFAULT,EPT}_SPTE_{HOST,MMU}_WRITABLE are used to keep track of why a given
78  * SPTE is write-protected. See is_writable_pte() for details.
79  */
80 
81 /* Bits 9 and 10 are ignored by all non-EPT PTEs. */
82 #define DEFAULT_SPTE_HOST_WRITABLE	BIT_ULL(9)
83 #define DEFAULT_SPTE_MMU_WRITABLE	BIT_ULL(10)
84 
85 /*
86  * Low ignored bits are at a premium for EPT, use high ignored bits, taking care
87  * to not overlap the A/D type mask or the saved access bits of access-tracked
88  * SPTEs when A/D bits are disabled.
89  */
90 #define EPT_SPTE_HOST_WRITABLE		BIT_ULL(57)
91 #define EPT_SPTE_MMU_WRITABLE		BIT_ULL(58)
92 
93 static_assert(!(EPT_SPTE_HOST_WRITABLE & SPTE_TDP_AD_MASK));
94 static_assert(!(EPT_SPTE_MMU_WRITABLE & SPTE_TDP_AD_MASK));
95 static_assert(!(EPT_SPTE_HOST_WRITABLE & SHADOW_ACC_TRACK_SAVED_MASK));
96 static_assert(!(EPT_SPTE_MMU_WRITABLE & SHADOW_ACC_TRACK_SAVED_MASK));
97 
98 /* Defined only to keep the above static asserts readable. */
99 #undef SHADOW_ACC_TRACK_SAVED_MASK
100 
101 /*
102  * Due to limited space in PTEs, the MMIO generation is a 19 bit subset of
103  * the memslots generation and is derived as follows:
104  *
105  * Bits 0-7 of the MMIO generation are propagated to spte bits 3-10
106  * Bits 8-18 of the MMIO generation are propagated to spte bits 52-62
107  *
108  * The KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS flag is intentionally not included in
109  * the MMIO generation number, as doing so would require stealing a bit from
110  * the "real" generation number and thus effectively halve the maximum number
111  * of MMIO generations that can be handled before encountering a wrap (which
112  * requires a full MMU zap).  The flag is instead explicitly queried when
113  * checking for MMIO spte cache hits.
114  */
115 
116 #define MMIO_SPTE_GEN_LOW_START		3
117 #define MMIO_SPTE_GEN_LOW_END		10
118 
119 #define MMIO_SPTE_GEN_HIGH_START	52
120 #define MMIO_SPTE_GEN_HIGH_END		62
121 
122 #define MMIO_SPTE_GEN_LOW_MASK		GENMASK_ULL(MMIO_SPTE_GEN_LOW_END, \
123 						    MMIO_SPTE_GEN_LOW_START)
124 #define MMIO_SPTE_GEN_HIGH_MASK		GENMASK_ULL(MMIO_SPTE_GEN_HIGH_END, \
125 						    MMIO_SPTE_GEN_HIGH_START)
126 static_assert(!(SPTE_MMU_PRESENT_MASK &
127 		(MMIO_SPTE_GEN_LOW_MASK | MMIO_SPTE_GEN_HIGH_MASK)));
128 
129 /*
130  * The SPTE MMIO mask must NOT overlap the MMIO generation bits or the
131  * MMU-present bit.  The generation obviously co-exists with the magic MMIO
132  * mask/value, and MMIO SPTEs are considered !MMU-present.
133  *
134  * The SPTE MMIO mask is allowed to use hardware "present" bits (i.e. all EPT
135  * RWX bits), all physical address bits (legal PA bits are used for "fast" MMIO
136  * and so they're off-limits for generation; additional checks ensure the mask
137  * doesn't overlap legal PA bits), and bit 63 (carved out for future usage).
138  */
139 #define SPTE_MMIO_ALLOWED_MASK (BIT_ULL(63) | GENMASK_ULL(51, 12) | GENMASK_ULL(2, 0))
140 static_assert(!(SPTE_MMIO_ALLOWED_MASK &
141 		(SPTE_MMU_PRESENT_MASK | MMIO_SPTE_GEN_LOW_MASK | MMIO_SPTE_GEN_HIGH_MASK)));
142 
143 #define MMIO_SPTE_GEN_LOW_BITS		(MMIO_SPTE_GEN_LOW_END - MMIO_SPTE_GEN_LOW_START + 1)
144 #define MMIO_SPTE_GEN_HIGH_BITS		(MMIO_SPTE_GEN_HIGH_END - MMIO_SPTE_GEN_HIGH_START + 1)
145 
146 /* remember to adjust the comment above as well if you change these */
147 static_assert(MMIO_SPTE_GEN_LOW_BITS == 8 && MMIO_SPTE_GEN_HIGH_BITS == 11);
148 
149 #define MMIO_SPTE_GEN_LOW_SHIFT		(MMIO_SPTE_GEN_LOW_START - 0)
150 #define MMIO_SPTE_GEN_HIGH_SHIFT	(MMIO_SPTE_GEN_HIGH_START - MMIO_SPTE_GEN_LOW_BITS)
151 
152 #define MMIO_SPTE_GEN_MASK		GENMASK_ULL(MMIO_SPTE_GEN_LOW_BITS + MMIO_SPTE_GEN_HIGH_BITS - 1, 0)
153 
154 /*
155  * Non-present SPTE value needs to set bit 63 for TDX, in order to suppress
156  * #VE and get EPT violations on non-present PTEs.  We can use the
157  * same value also without TDX for both VMX and SVM:
158  *
159  * For SVM NPT, for non-present spte (bit 0 = 0), other bits are ignored.
160  * For VMX EPT, bit 63 is ignored if #VE is disabled. (EPT_VIOLATION_VE=0)
161  *              bit 63 is #VE suppress if #VE is enabled. (EPT_VIOLATION_VE=1)
162  */
163 #ifdef CONFIG_X86_64
164 #define SHADOW_NONPRESENT_VALUE	BIT_ULL(63)
165 static_assert(!(SHADOW_NONPRESENT_VALUE & SPTE_MMU_PRESENT_MASK));
166 #else
167 #define SHADOW_NONPRESENT_VALUE	0ULL
168 #endif
169 
170 extern u64 __read_mostly shadow_host_writable_mask;
171 extern u64 __read_mostly shadow_mmu_writable_mask;
172 extern u64 __read_mostly shadow_nx_mask;
173 extern u64 __read_mostly shadow_x_mask; /* mutual exclusive with nx_mask */
174 extern u64 __read_mostly shadow_user_mask;
175 extern u64 __read_mostly shadow_accessed_mask;
176 extern u64 __read_mostly shadow_dirty_mask;
177 extern u64 __read_mostly shadow_mmio_value;
178 extern u64 __read_mostly shadow_mmio_mask;
179 extern u64 __read_mostly shadow_mmio_access_mask;
180 extern u64 __read_mostly shadow_present_mask;
181 extern u64 __read_mostly shadow_memtype_mask;
182 extern u64 __read_mostly shadow_me_value;
183 extern u64 __read_mostly shadow_me_mask;
184 
185 /*
186  * SPTEs in MMUs without A/D bits are marked with SPTE_TDP_AD_DISABLED;
187  * shadow_acc_track_mask is the set of bits to be cleared in non-accessed
188  * pages.
189  */
190 extern u64 __read_mostly shadow_acc_track_mask;
191 
192 /*
193  * This mask must be set on all non-zero Non-Present or Reserved SPTEs in order
194  * to guard against L1TF attacks.
195  */
196 extern u64 __read_mostly shadow_nonpresent_or_rsvd_mask;
197 
198 /*
199  * The number of high-order 1 bits to use in the mask above.
200  */
201 #define SHADOW_NONPRESENT_OR_RSVD_MASK_LEN 5
202 
203 /*
204  * If a thread running without exclusive control of the MMU lock must perform a
205  * multi-part operation on an SPTE, it can set the SPTE to FROZEN_SPTE as a
206  * non-present intermediate value. Other threads which encounter this value
207  * should not modify the SPTE.
208  *
209  * Use a semi-arbitrary value that doesn't set RWX bits, i.e. is not-present on
210  * both AMD and Intel CPUs, and doesn't set PFN bits, i.e. doesn't create a L1TF
211  * vulnerability.
212  *
213  * Only used by the TDP MMU.
214  */
215 #define FROZEN_SPTE	(SHADOW_NONPRESENT_VALUE | 0x5a0ULL)
216 
217 /* Frozen SPTEs must not be misconstrued as shadow present PTEs. */
218 static_assert(!(FROZEN_SPTE & SPTE_MMU_PRESENT_MASK));
219 
220 static inline bool is_frozen_spte(u64 spte)
221 {
222 	return spte == FROZEN_SPTE;
223 }
224 
225 /* Get an SPTE's index into its parent's page table (and the spt array). */
226 static inline int spte_index(u64 *sptep)
227 {
228 	return ((unsigned long)sptep / sizeof(*sptep)) & (SPTE_ENT_PER_PAGE - 1);
229 }
230 
231 /*
232  * In some cases, we need to preserve the GFN of a non-present or reserved
233  * SPTE when we usurp the upper five bits of the physical address space to
234  * defend against L1TF, e.g. for MMIO SPTEs.  To preserve the GFN, we'll
235  * shift bits of the GFN that overlap with shadow_nonpresent_or_rsvd_mask
236  * left into the reserved bits, i.e. the GFN in the SPTE will be split into
237  * high and low parts.  This mask covers the lower bits of the GFN.
238  */
239 extern u64 __read_mostly shadow_nonpresent_or_rsvd_lower_gfn_mask;
240 
241 static inline struct kvm_mmu_page *to_shadow_page(hpa_t shadow_page)
242 {
243 	struct page *page = pfn_to_page((shadow_page) >> PAGE_SHIFT);
244 
245 	return (struct kvm_mmu_page *)page_private(page);
246 }
247 
248 static inline struct kvm_mmu_page *spte_to_child_sp(u64 spte)
249 {
250 	return to_shadow_page(spte & SPTE_BASE_ADDR_MASK);
251 }
252 
253 static inline struct kvm_mmu_page *sptep_to_sp(u64 *sptep)
254 {
255 	return to_shadow_page(__pa(sptep));
256 }
257 
258 static inline struct kvm_mmu_page *root_to_sp(hpa_t root)
259 {
260 	if (kvm_mmu_is_dummy_root(root))
261 		return NULL;
262 
263 	/*
264 	 * The "root" may be a special root, e.g. a PAE entry, treat it as a
265 	 * SPTE to ensure any non-PA bits are dropped.
266 	 */
267 	return spte_to_child_sp(root);
268 }
269 
270 static inline bool is_mmio_spte(struct kvm *kvm, u64 spte)
271 {
272 	return (spte & shadow_mmio_mask) == kvm->arch.shadow_mmio_value &&
273 	       likely(enable_mmio_caching);
274 }
275 
276 static inline bool is_shadow_present_pte(u64 pte)
277 {
278 	return !!(pte & SPTE_MMU_PRESENT_MASK);
279 }
280 
281 static inline bool is_ept_ve_possible(u64 spte)
282 {
283 	return (shadow_present_mask & VMX_EPT_SUPPRESS_VE_BIT) &&
284 	       !(spte & VMX_EPT_SUPPRESS_VE_BIT) &&
285 	       (spte & VMX_EPT_RWX_MASK) != VMX_EPT_MISCONFIG_WX_VALUE;
286 }
287 
288 /*
289  * Returns true if A/D bits are supported in hardware and are enabled by KVM.
290  * When enabled, KVM uses A/D bits for all non-nested MMUs.  Because L1 can
291  * disable A/D bits in EPTP12, SP and SPTE variants are needed to handle the
292  * scenario where KVM is using A/D bits for L1, but not L2.
293  */
294 static inline bool kvm_ad_enabled(void)
295 {
296 	return !!shadow_accessed_mask;
297 }
298 
299 static inline bool sp_ad_disabled(struct kvm_mmu_page *sp)
300 {
301 	return sp->role.ad_disabled;
302 }
303 
304 static inline bool spte_ad_enabled(u64 spte)
305 {
306 	KVM_MMU_WARN_ON(!is_shadow_present_pte(spte));
307 	return (spte & SPTE_TDP_AD_MASK) != SPTE_TDP_AD_DISABLED;
308 }
309 
310 static inline bool spte_ad_need_write_protect(u64 spte)
311 {
312 	KVM_MMU_WARN_ON(!is_shadow_present_pte(spte));
313 	/*
314 	 * This is benign for non-TDP SPTEs as SPTE_TDP_AD_ENABLED is '0',
315 	 * and non-TDP SPTEs will never set these bits.  Optimize for 64-bit
316 	 * TDP and do the A/D type check unconditionally.
317 	 */
318 	return (spte & SPTE_TDP_AD_MASK) != SPTE_TDP_AD_ENABLED;
319 }
320 
321 static inline u64 spte_shadow_accessed_mask(u64 spte)
322 {
323 	KVM_MMU_WARN_ON(!is_shadow_present_pte(spte));
324 	return spte_ad_enabled(spte) ? shadow_accessed_mask : 0;
325 }
326 
327 static inline u64 spte_shadow_dirty_mask(u64 spte)
328 {
329 	KVM_MMU_WARN_ON(!is_shadow_present_pte(spte));
330 	return spte_ad_enabled(spte) ? shadow_dirty_mask : 0;
331 }
332 
333 static inline bool is_access_track_spte(u64 spte)
334 {
335 	return !spte_ad_enabled(spte) && (spte & shadow_acc_track_mask) == 0;
336 }
337 
338 static inline bool is_large_pte(u64 pte)
339 {
340 	return pte & PT_PAGE_SIZE_MASK;
341 }
342 
343 static inline bool is_last_spte(u64 pte, int level)
344 {
345 	return (level == PG_LEVEL_4K) || is_large_pte(pte);
346 }
347 
348 static inline bool is_executable_pte(u64 spte)
349 {
350 	return (spte & (shadow_x_mask | shadow_nx_mask)) == shadow_x_mask;
351 }
352 
353 static inline kvm_pfn_t spte_to_pfn(u64 pte)
354 {
355 	return (pte & SPTE_BASE_ADDR_MASK) >> PAGE_SHIFT;
356 }
357 
358 static inline bool is_accessed_spte(u64 spte)
359 {
360 	u64 accessed_mask = spte_shadow_accessed_mask(spte);
361 
362 	return accessed_mask ? spte & accessed_mask
363 			     : !is_access_track_spte(spte);
364 }
365 
366 static inline bool is_dirty_spte(u64 spte)
367 {
368 	u64 dirty_mask = spte_shadow_dirty_mask(spte);
369 
370 	return dirty_mask ? spte & dirty_mask : spte & PT_WRITABLE_MASK;
371 }
372 
373 static inline u64 get_rsvd_bits(struct rsvd_bits_validate *rsvd_check, u64 pte,
374 				int level)
375 {
376 	int bit7 = (pte >> 7) & 1;
377 
378 	return rsvd_check->rsvd_bits_mask[bit7][level-1];
379 }
380 
381 static inline bool __is_rsvd_bits_set(struct rsvd_bits_validate *rsvd_check,
382 				      u64 pte, int level)
383 {
384 	return pte & get_rsvd_bits(rsvd_check, pte, level);
385 }
386 
387 static inline bool __is_bad_mt_xwr(struct rsvd_bits_validate *rsvd_check,
388 				   u64 pte)
389 {
390 	return rsvd_check->bad_mt_xwr & BIT_ULL(pte & 0x3f);
391 }
392 
393 static __always_inline bool is_rsvd_spte(struct rsvd_bits_validate *rsvd_check,
394 					 u64 spte, int level)
395 {
396 	return __is_bad_mt_xwr(rsvd_check, spte) ||
397 	       __is_rsvd_bits_set(rsvd_check, spte, level);
398 }
399 
400 /*
401  * A shadow-present leaf SPTE may be non-writable for 4 possible reasons:
402  *
403  *  1. To intercept writes for dirty logging. KVM write-protects huge pages
404  *     so that they can be split down into the dirty logging
405  *     granularity (4KiB) whenever the guest writes to them. KVM also
406  *     write-protects 4KiB pages so that writes can be recorded in the dirty log
407  *     (e.g. if not using PML). SPTEs are write-protected for dirty logging
408  *     during the VM-iotcls that enable dirty logging.
409  *
410  *  2. To intercept writes to guest page tables that KVM is shadowing. When a
411  *     guest writes to its page table the corresponding shadow page table will
412  *     be marked "unsync". That way KVM knows which shadow page tables need to
413  *     be updated on the next TLB flush, INVLPG, etc. and which do not.
414  *
415  *  3. To prevent guest writes to read-only memory, such as for memory in a
416  *     read-only memslot or guest memory backed by a read-only VMA. Writes to
417  *     such pages are disallowed entirely.
418  *
419  *  4. To emulate the Accessed bit for SPTEs without A/D bits.  Note, in this
420  *     case, the SPTE is access-protected, not just write-protected!
421  *
422  * For cases #1 and #4, KVM can safely make such SPTEs writable without taking
423  * mmu_lock as capturing the Accessed/Dirty state doesn't require taking it.
424  * To differentiate #1 and #4 from #2 and #3, KVM uses two software-only bits
425  * in the SPTE:
426  *
427  *  shadow_mmu_writable_mask, aka MMU-writable -
428  *    Cleared on SPTEs that KVM is currently write-protecting for shadow paging
429  *    purposes (case 2 above).
430  *
431  *  shadow_host_writable_mask, aka Host-writable -
432  *    Cleared on SPTEs that are not host-writable (case 3 above)
433  *
434  * Note, not all possible combinations of PT_WRITABLE_MASK,
435  * shadow_mmu_writable_mask, and shadow_host_writable_mask are valid. A given
436  * SPTE can be in only one of the following states, which map to the
437  * aforementioned 3 cases:
438  *
439  *   shadow_host_writable_mask | shadow_mmu_writable_mask | PT_WRITABLE_MASK
440  *   ------------------------- | ------------------------ | ----------------
441  *   1                         | 1                        | 1       (writable)
442  *   1                         | 1                        | 0       (case 1)
443  *   1                         | 0                        | 0       (case 2)
444  *   0                         | 0                        | 0       (case 3)
445  *
446  * The valid combinations of these bits are checked by
447  * check_spte_writable_invariants() whenever an SPTE is modified.
448  *
449  * Clearing the MMU-writable bit is always done under the MMU lock and always
450  * accompanied by a TLB flush before dropping the lock to avoid corrupting the
451  * shadow page tables between vCPUs. Write-protecting an SPTE for dirty logging
452  * (which does not clear the MMU-writable bit), does not flush TLBs before
453  * dropping the lock, as it only needs to synchronize guest writes with the
454  * dirty bitmap. Similarly, making the SPTE inaccessible (and non-writable) for
455  * access-tracking via the clear_young() MMU notifier also does not flush TLBs.
456  *
457  * So, there is the problem: clearing the MMU-writable bit can encounter a
458  * write-protected SPTE while CPUs still have writable mappings for that SPTE
459  * cached in their TLB. To address this, KVM always flushes TLBs when
460  * write-protecting SPTEs if the MMU-writable bit is set on the old SPTE.
461  *
462  * The Host-writable bit is not modified on present SPTEs, it is only set or
463  * cleared when an SPTE is first faulted in from non-present and then remains
464  * immutable.
465  */
466 static inline bool is_writable_pte(unsigned long pte)
467 {
468 	return pte & PT_WRITABLE_MASK;
469 }
470 
471 /* Note: spte must be a shadow-present leaf SPTE. */
472 static inline void check_spte_writable_invariants(u64 spte)
473 {
474 	if (spte & shadow_mmu_writable_mask)
475 		WARN_ONCE(!(spte & shadow_host_writable_mask),
476 			  KBUILD_MODNAME ": MMU-writable SPTE is not Host-writable: %llx",
477 			  spte);
478 	else
479 		WARN_ONCE(is_writable_pte(spte),
480 			  KBUILD_MODNAME ": Writable SPTE is not MMU-writable: %llx", spte);
481 }
482 
483 static inline bool is_mmu_writable_spte(u64 spte)
484 {
485 	return spte & shadow_mmu_writable_mask;
486 }
487 
488 static inline u64 get_mmio_spte_generation(u64 spte)
489 {
490 	u64 gen;
491 
492 	gen = (spte & MMIO_SPTE_GEN_LOW_MASK) >> MMIO_SPTE_GEN_LOW_SHIFT;
493 	gen |= (spte & MMIO_SPTE_GEN_HIGH_MASK) >> MMIO_SPTE_GEN_HIGH_SHIFT;
494 	return gen;
495 }
496 
497 bool spte_has_volatile_bits(u64 spte);
498 
499 bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
500 	       const struct kvm_memory_slot *slot,
501 	       unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn,
502 	       u64 old_spte, bool prefetch, bool can_unsync,
503 	       bool host_writable, u64 *new_spte);
504 u64 make_huge_page_split_spte(struct kvm *kvm, u64 huge_spte,
505 		      	      union kvm_mmu_page_role role, int index);
506 u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled);
507 u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access);
508 u64 mark_spte_for_access_track(u64 spte);
509 
510 /* Restore an acc-track PTE back to a regular PTE */
511 static inline u64 restore_acc_track_spte(u64 spte)
512 {
513 	u64 saved_bits = (spte >> SHADOW_ACC_TRACK_SAVED_BITS_SHIFT)
514 			 & SHADOW_ACC_TRACK_SAVED_BITS_MASK;
515 
516 	spte &= ~shadow_acc_track_mask;
517 	spte &= ~(SHADOW_ACC_TRACK_SAVED_BITS_MASK <<
518 		  SHADOW_ACC_TRACK_SAVED_BITS_SHIFT);
519 	spte |= saved_bits;
520 
521 	return spte;
522 }
523 
524 void __init kvm_mmu_spte_module_init(void);
525 void kvm_mmu_reset_all_pte_masks(void);
526 
527 #endif
528