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_internal.h" 7 8 /* 9 * A MMU present SPTE is backed by actual memory and may or may not be present 10 * in hardware. E.g. MMIO SPTEs are not considered present. Use bit 11, as it 11 * is ignored by all flavors of SPTEs and checking a low bit often generates 12 * better code than for a high bit, e.g. 56+. MMU present checks are pervasive 13 * enough that the improved code generation is noticeable in KVM's footprint. 14 */ 15 #define SPTE_MMU_PRESENT_MASK BIT_ULL(11) 16 17 /* 18 * TDP SPTES (more specifically, EPT SPTEs) may not have A/D bits, and may also 19 * be restricted to using write-protection (for L2 when CPU dirty logging, i.e. 20 * PML, is enabled). Use bits 52 and 53 to hold the type of A/D tracking that 21 * is must be employed for a given TDP SPTE. 22 * 23 * Note, the "enabled" mask must be '0', as bits 62:52 are _reserved_ for PAE 24 * paging, including NPT PAE. This scheme works because legacy shadow paging 25 * is guaranteed to have A/D bits and write-protection is forced only for 26 * TDP with CPU dirty logging (PML). If NPT ever gains PML-like support, it 27 * must be restricted to 64-bit KVM. 28 */ 29 #define SPTE_TDP_AD_SHIFT 52 30 #define SPTE_TDP_AD_MASK (3ULL << SPTE_TDP_AD_SHIFT) 31 #define SPTE_TDP_AD_ENABLED_MASK (0ULL << SPTE_TDP_AD_SHIFT) 32 #define SPTE_TDP_AD_DISABLED_MASK (1ULL << SPTE_TDP_AD_SHIFT) 33 #define SPTE_TDP_AD_WRPROT_ONLY_MASK (2ULL << SPTE_TDP_AD_SHIFT) 34 static_assert(SPTE_TDP_AD_ENABLED_MASK == 0); 35 36 #ifdef CONFIG_DYNAMIC_PHYSICAL_MASK 37 #define PT64_BASE_ADDR_MASK (physical_mask & ~(u64)(PAGE_SIZE-1)) 38 #else 39 #define PT64_BASE_ADDR_MASK (((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1)) 40 #endif 41 #define PT64_LVL_ADDR_MASK(level) \ 42 (PT64_BASE_ADDR_MASK & ~((1ULL << (PAGE_SHIFT + (((level) - 1) \ 43 * PT64_LEVEL_BITS))) - 1)) 44 #define PT64_LVL_OFFSET_MASK(level) \ 45 (PT64_BASE_ADDR_MASK & ((1ULL << (PAGE_SHIFT + (((level) - 1) \ 46 * PT64_LEVEL_BITS))) - 1)) 47 48 #define PT64_PERM_MASK (PT_PRESENT_MASK | PT_WRITABLE_MASK | shadow_user_mask \ 49 | shadow_x_mask | shadow_nx_mask | shadow_me_mask) 50 51 #define ACC_EXEC_MASK 1 52 #define ACC_WRITE_MASK PT_WRITABLE_MASK 53 #define ACC_USER_MASK PT_USER_MASK 54 #define ACC_ALL (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK) 55 56 /* The mask for the R/X bits in EPT PTEs */ 57 #define PT64_EPT_READABLE_MASK 0x1ull 58 #define PT64_EPT_EXECUTABLE_MASK 0x4ull 59 60 #define PT64_LEVEL_BITS 9 61 62 #define PT64_LEVEL_SHIFT(level) \ 63 (PAGE_SHIFT + (level - 1) * PT64_LEVEL_BITS) 64 65 #define PT64_INDEX(address, level)\ 66 (((address) >> PT64_LEVEL_SHIFT(level)) & ((1 << PT64_LEVEL_BITS) - 1)) 67 #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level) 68 69 /* Bits 9 and 10 are ignored by all non-EPT PTEs. */ 70 #define DEFAULT_SPTE_HOST_WRITEABLE BIT_ULL(9) 71 #define DEFAULT_SPTE_MMU_WRITEABLE BIT_ULL(10) 72 73 /* 74 * The mask/shift to use for saving the original R/X bits when marking the PTE 75 * as not-present for access tracking purposes. We do not save the W bit as the 76 * PTEs being access tracked also need to be dirty tracked, so the W bit will be 77 * restored only when a write is attempted to the page. This mask obviously 78 * must not overlap the A/D type mask. 79 */ 80 #define SHADOW_ACC_TRACK_SAVED_BITS_MASK (PT64_EPT_READABLE_MASK | \ 81 PT64_EPT_EXECUTABLE_MASK) 82 #define SHADOW_ACC_TRACK_SAVED_BITS_SHIFT 54 83 #define SHADOW_ACC_TRACK_SAVED_MASK (SHADOW_ACC_TRACK_SAVED_BITS_MASK << \ 84 SHADOW_ACC_TRACK_SAVED_BITS_SHIFT) 85 static_assert(!(SPTE_TDP_AD_MASK & SHADOW_ACC_TRACK_SAVED_MASK)); 86 87 /* 88 * Low ignored bits are at a premium for EPT, use high ignored bits, taking care 89 * to not overlap the A/D type mask or the saved access bits of access-tracked 90 * SPTEs when A/D bits are disabled. 91 */ 92 #define EPT_SPTE_HOST_WRITABLE BIT_ULL(57) 93 #define EPT_SPTE_MMU_WRITABLE BIT_ULL(58) 94 95 static_assert(!(EPT_SPTE_HOST_WRITABLE & SPTE_TDP_AD_MASK)); 96 static_assert(!(EPT_SPTE_MMU_WRITABLE & SPTE_TDP_AD_MASK)); 97 static_assert(!(EPT_SPTE_HOST_WRITABLE & SHADOW_ACC_TRACK_SAVED_MASK)); 98 static_assert(!(EPT_SPTE_MMU_WRITABLE & SHADOW_ACC_TRACK_SAVED_MASK)); 99 100 /* Defined only to keep the above static asserts readable. */ 101 #undef SHADOW_ACC_TRACK_SAVED_MASK 102 103 /* 104 * Due to limited space in PTEs, the MMIO generation is a 19 bit subset of 105 * the memslots generation and is derived as follows: 106 * 107 * Bits 0-7 of the MMIO generation are propagated to spte bits 3-10 108 * Bits 8-18 of the MMIO generation are propagated to spte bits 52-62 109 * 110 * The KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS flag is intentionally not included in 111 * the MMIO generation number, as doing so would require stealing a bit from 112 * the "real" generation number and thus effectively halve the maximum number 113 * of MMIO generations that can be handled before encountering a wrap (which 114 * requires a full MMU zap). The flag is instead explicitly queried when 115 * checking for MMIO spte cache hits. 116 */ 117 118 #define MMIO_SPTE_GEN_LOW_START 3 119 #define MMIO_SPTE_GEN_LOW_END 10 120 121 #define MMIO_SPTE_GEN_HIGH_START 52 122 #define MMIO_SPTE_GEN_HIGH_END 62 123 124 #define MMIO_SPTE_GEN_LOW_MASK GENMASK_ULL(MMIO_SPTE_GEN_LOW_END, \ 125 MMIO_SPTE_GEN_LOW_START) 126 #define MMIO_SPTE_GEN_HIGH_MASK GENMASK_ULL(MMIO_SPTE_GEN_HIGH_END, \ 127 MMIO_SPTE_GEN_HIGH_START) 128 static_assert(!(SPTE_MMU_PRESENT_MASK & 129 (MMIO_SPTE_GEN_LOW_MASK | MMIO_SPTE_GEN_HIGH_MASK))); 130 131 #define MMIO_SPTE_GEN_LOW_BITS (MMIO_SPTE_GEN_LOW_END - MMIO_SPTE_GEN_LOW_START + 1) 132 #define MMIO_SPTE_GEN_HIGH_BITS (MMIO_SPTE_GEN_HIGH_END - MMIO_SPTE_GEN_HIGH_START + 1) 133 134 /* remember to adjust the comment above as well if you change these */ 135 static_assert(MMIO_SPTE_GEN_LOW_BITS == 8 && MMIO_SPTE_GEN_HIGH_BITS == 11); 136 137 #define MMIO_SPTE_GEN_LOW_SHIFT (MMIO_SPTE_GEN_LOW_START - 0) 138 #define MMIO_SPTE_GEN_HIGH_SHIFT (MMIO_SPTE_GEN_HIGH_START - MMIO_SPTE_GEN_LOW_BITS) 139 140 #define MMIO_SPTE_GEN_MASK GENMASK_ULL(MMIO_SPTE_GEN_LOW_BITS + MMIO_SPTE_GEN_HIGH_BITS - 1, 0) 141 142 extern u64 __read_mostly shadow_host_writable_mask; 143 extern u64 __read_mostly shadow_mmu_writable_mask; 144 extern u64 __read_mostly shadow_nx_mask; 145 extern u64 __read_mostly shadow_x_mask; /* mutual exclusive with nx_mask */ 146 extern u64 __read_mostly shadow_user_mask; 147 extern u64 __read_mostly shadow_accessed_mask; 148 extern u64 __read_mostly shadow_dirty_mask; 149 extern u64 __read_mostly shadow_mmio_value; 150 extern u64 __read_mostly shadow_mmio_mask; 151 extern u64 __read_mostly shadow_mmio_access_mask; 152 extern u64 __read_mostly shadow_present_mask; 153 extern u64 __read_mostly shadow_me_mask; 154 155 /* 156 * SPTEs in MMUs without A/D bits are marked with SPTE_TDP_AD_DISABLED_MASK; 157 * shadow_acc_track_mask is the set of bits to be cleared in non-accessed 158 * pages. 159 */ 160 extern u64 __read_mostly shadow_acc_track_mask; 161 162 /* 163 * This mask must be set on all non-zero Non-Present or Reserved SPTEs in order 164 * to guard against L1TF attacks. 165 */ 166 extern u64 __read_mostly shadow_nonpresent_or_rsvd_mask; 167 168 /* 169 * The number of high-order 1 bits to use in the mask above. 170 */ 171 #define SHADOW_NONPRESENT_OR_RSVD_MASK_LEN 5 172 173 /* 174 * If a thread running without exclusive control of the MMU lock must perform a 175 * multi-part operation on an SPTE, it can set the SPTE to REMOVED_SPTE as a 176 * non-present intermediate value. Other threads which encounter this value 177 * should not modify the SPTE. 178 * 179 * Use a semi-arbitrary value that doesn't set RWX bits, i.e. is not-present on 180 * bot AMD and Intel CPUs, and doesn't set PFN bits, i.e. doesn't create a L1TF 181 * vulnerability. Use only low bits to avoid 64-bit immediates. 182 * 183 * Only used by the TDP MMU. 184 */ 185 #define REMOVED_SPTE 0x5a0ULL 186 187 /* Removed SPTEs must not be misconstrued as shadow present PTEs. */ 188 static_assert(!(REMOVED_SPTE & SPTE_MMU_PRESENT_MASK)); 189 190 static inline bool is_removed_spte(u64 spte) 191 { 192 return spte == REMOVED_SPTE; 193 } 194 195 /* 196 * In some cases, we need to preserve the GFN of a non-present or reserved 197 * SPTE when we usurp the upper five bits of the physical address space to 198 * defend against L1TF, e.g. for MMIO SPTEs. To preserve the GFN, we'll 199 * shift bits of the GFN that overlap with shadow_nonpresent_or_rsvd_mask 200 * left into the reserved bits, i.e. the GFN in the SPTE will be split into 201 * high and low parts. This mask covers the lower bits of the GFN. 202 */ 203 extern u64 __read_mostly shadow_nonpresent_or_rsvd_lower_gfn_mask; 204 205 /* 206 * The number of non-reserved physical address bits irrespective of features 207 * that repurpose legal bits, e.g. MKTME. 208 */ 209 extern u8 __read_mostly shadow_phys_bits; 210 211 static inline bool is_mmio_spte(u64 spte) 212 { 213 return (spte & shadow_mmio_mask) == shadow_mmio_value && 214 likely(shadow_mmio_value); 215 } 216 217 static inline bool is_shadow_present_pte(u64 pte) 218 { 219 return !!(pte & SPTE_MMU_PRESENT_MASK); 220 } 221 222 static inline bool sp_ad_disabled(struct kvm_mmu_page *sp) 223 { 224 return sp->role.ad_disabled; 225 } 226 227 static inline bool spte_ad_enabled(u64 spte) 228 { 229 MMU_WARN_ON(!is_shadow_present_pte(spte)); 230 return (spte & SPTE_TDP_AD_MASK) != SPTE_TDP_AD_DISABLED_MASK; 231 } 232 233 static inline bool spte_ad_need_write_protect(u64 spte) 234 { 235 MMU_WARN_ON(!is_shadow_present_pte(spte)); 236 /* 237 * This is benign for non-TDP SPTEs as SPTE_TDP_AD_ENABLED_MASK is '0', 238 * and non-TDP SPTEs will never set these bits. Optimize for 64-bit 239 * TDP and do the A/D type check unconditionally. 240 */ 241 return (spte & SPTE_TDP_AD_MASK) != SPTE_TDP_AD_ENABLED_MASK; 242 } 243 244 static inline u64 spte_shadow_accessed_mask(u64 spte) 245 { 246 MMU_WARN_ON(!is_shadow_present_pte(spte)); 247 return spte_ad_enabled(spte) ? shadow_accessed_mask : 0; 248 } 249 250 static inline u64 spte_shadow_dirty_mask(u64 spte) 251 { 252 MMU_WARN_ON(!is_shadow_present_pte(spte)); 253 return spte_ad_enabled(spte) ? shadow_dirty_mask : 0; 254 } 255 256 static inline bool is_access_track_spte(u64 spte) 257 { 258 return !spte_ad_enabled(spte) && (spte & shadow_acc_track_mask) == 0; 259 } 260 261 static inline bool is_large_pte(u64 pte) 262 { 263 return pte & PT_PAGE_SIZE_MASK; 264 } 265 266 static inline bool is_last_spte(u64 pte, int level) 267 { 268 return (level == PG_LEVEL_4K) || is_large_pte(pte); 269 } 270 271 static inline bool is_executable_pte(u64 spte) 272 { 273 return (spte & (shadow_x_mask | shadow_nx_mask)) == shadow_x_mask; 274 } 275 276 static inline kvm_pfn_t spte_to_pfn(u64 pte) 277 { 278 return (pte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT; 279 } 280 281 static inline bool is_accessed_spte(u64 spte) 282 { 283 u64 accessed_mask = spte_shadow_accessed_mask(spte); 284 285 return accessed_mask ? spte & accessed_mask 286 : !is_access_track_spte(spte); 287 } 288 289 static inline bool is_dirty_spte(u64 spte) 290 { 291 u64 dirty_mask = spte_shadow_dirty_mask(spte); 292 293 return dirty_mask ? spte & dirty_mask : spte & PT_WRITABLE_MASK; 294 } 295 296 static inline bool spte_can_locklessly_be_made_writable(u64 spte) 297 { 298 return (spte & shadow_host_writable_mask) && 299 (spte & shadow_mmu_writable_mask); 300 } 301 302 static inline u64 get_mmio_spte_generation(u64 spte) 303 { 304 u64 gen; 305 306 gen = (spte & MMIO_SPTE_GEN_LOW_MASK) >> MMIO_SPTE_GEN_LOW_SHIFT; 307 gen |= (spte & MMIO_SPTE_GEN_HIGH_MASK) >> MMIO_SPTE_GEN_HIGH_SHIFT; 308 return gen; 309 } 310 311 /* Bits which may be returned by set_spte() */ 312 #define SET_SPTE_WRITE_PROTECTED_PT BIT(0) 313 #define SET_SPTE_NEED_REMOTE_TLB_FLUSH BIT(1) 314 #define SET_SPTE_SPURIOUS BIT(2) 315 316 int make_spte(struct kvm_vcpu *vcpu, unsigned int pte_access, int level, 317 gfn_t gfn, kvm_pfn_t pfn, u64 old_spte, bool speculative, 318 bool can_unsync, bool host_writable, bool ad_disabled, 319 u64 *new_spte); 320 u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled); 321 u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access); 322 u64 mark_spte_for_access_track(u64 spte); 323 u64 kvm_mmu_changed_pte_notifier_make_spte(u64 old_spte, kvm_pfn_t new_pfn); 324 325 void kvm_mmu_reset_all_pte_masks(void); 326 327 #endif 328