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; 135 136 static inline int kvm_mmu_role_as_id(union kvm_mmu_page_role role) 137 { 138 return role.smm ? 1 : 0; 139 } 140 141 static inline int kvm_mmu_page_as_id(struct kvm_mmu_page *sp) 142 { 143 return kvm_mmu_role_as_id(sp->role); 144 } 145 146 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 } 158 159 int mmu_try_to_unsync_pages(struct kvm *kvm, const struct kvm_memory_slot *slot, 160 gfn_t gfn, bool can_unsync, bool prefetch); 161 162 void kvm_mmu_gfn_disallow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn); 163 void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn); 164 bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm, 165 struct kvm_memory_slot *slot, u64 gfn, 166 int min_level); 167 void kvm_flush_remote_tlbs_with_address(struct kvm *kvm, 168 u64 start_gfn, u64 pages); 169 unsigned int pte_list_count(struct kvm_rmap_head *rmap_head); 170 171 extern int nx_huge_pages; 172 static inline bool is_nx_huge_page_enabled(struct kvm *kvm) 173 { 174 return READ_ONCE(nx_huge_pages) && !kvm->arch.disable_nx_huge_pages; 175 } 176 177 struct kvm_page_fault { 178 /* arguments to kvm_mmu_do_page_fault. */ 179 const gpa_t addr; 180 const u32 error_code; 181 const bool prefetch; 182 183 /* Derived from error_code. */ 184 const bool exec; 185 const bool write; 186 const bool present; 187 const bool rsvd; 188 const bool user; 189 190 /* Derived from mmu and global state. */ 191 const bool is_tdp; 192 const bool nx_huge_page_workaround_enabled; 193 194 /* 195 * Whether a >4KB mapping can be created or is forbidden due to NX 196 * hugepages. 197 */ 198 bool huge_page_disallowed; 199 200 /* 201 * Maximum page size that can be created for this fault; input to 202 * FNAME(fetch), __direct_map and kvm_tdp_mmu_map. 203 */ 204 u8 max_level; 205 206 /* 207 * Page size that can be created based on the max_level and the 208 * page size used by the host mapping. 209 */ 210 u8 req_level; 211 212 /* 213 * Page size that will be created based on the req_level and 214 * huge_page_disallowed. 215 */ 216 u8 goal_level; 217 218 /* Shifted addr, or result of guest page table walk if addr is a gva. */ 219 gfn_t gfn; 220 221 /* The memslot containing gfn. May be NULL. */ 222 struct kvm_memory_slot *slot; 223 224 /* Outputs of kvm_faultin_pfn. */ 225 kvm_pfn_t pfn; 226 hva_t hva; 227 bool map_writable; 228 }; 229 230 int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); 231 232 /* 233 * Return values of handle_mmio_page_fault(), mmu.page_fault(), fast_page_fault(), 234 * and of course kvm_mmu_do_page_fault(). 235 * 236 * RET_PF_CONTINUE: So far, so good, keep handling the page fault. 237 * RET_PF_RETRY: let CPU fault again on the address. 238 * RET_PF_EMULATE: mmio page fault, emulate the instruction directly. 239 * RET_PF_INVALID: the spte is invalid, let the real page fault path update it. 240 * RET_PF_FIXED: The faulting entry has been fixed. 241 * RET_PF_SPURIOUS: The faulting entry was already fixed, e.g. by another vCPU. 242 * 243 * Any names added to this enum should be exported to userspace for use in 244 * tracepoints via TRACE_DEFINE_ENUM() in mmutrace.h 245 * 246 * Note, all values must be greater than or equal to zero so as not to encroach 247 * on -errno return values. Somewhat arbitrarily use '0' for CONTINUE, which 248 * will allow for efficient machine code when checking for CONTINUE, e.g. 249 * "TEST %rax, %rax, JNZ", as all "stop!" values are non-zero. 250 */ 251 enum { 252 RET_PF_CONTINUE = 0, 253 RET_PF_RETRY, 254 RET_PF_EMULATE, 255 RET_PF_INVALID, 256 RET_PF_FIXED, 257 RET_PF_SPURIOUS, 258 }; 259 260 static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, 261 u32 err, bool prefetch) 262 { 263 struct kvm_page_fault fault = { 264 .addr = cr2_or_gpa, 265 .error_code = err, 266 .exec = err & PFERR_FETCH_MASK, 267 .write = err & PFERR_WRITE_MASK, 268 .present = err & PFERR_PRESENT_MASK, 269 .rsvd = err & PFERR_RSVD_MASK, 270 .user = err & PFERR_USER_MASK, 271 .prefetch = prefetch, 272 .is_tdp = likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault), 273 .nx_huge_page_workaround_enabled = 274 is_nx_huge_page_enabled(vcpu->kvm), 275 276 .max_level = KVM_MAX_HUGEPAGE_LEVEL, 277 .req_level = PG_LEVEL_4K, 278 .goal_level = PG_LEVEL_4K, 279 }; 280 int r; 281 282 /* 283 * Async #PF "faults", a.k.a. prefetch faults, are not faults from the 284 * guest perspective and have already been counted at the time of the 285 * original fault. 286 */ 287 if (!prefetch) 288 vcpu->stat.pf_taken++; 289 290 if (IS_ENABLED(CONFIG_RETPOLINE) && fault.is_tdp) 291 r = kvm_tdp_page_fault(vcpu, &fault); 292 else 293 r = vcpu->arch.mmu->page_fault(vcpu, &fault); 294 295 /* 296 * Similar to above, prefetch faults aren't truly spurious, and the 297 * async #PF path doesn't do emulation. Do count faults that are fixed 298 * by the async #PF handler though, otherwise they'll never be counted. 299 */ 300 if (r == RET_PF_FIXED) 301 vcpu->stat.pf_fixed++; 302 else if (prefetch) 303 ; 304 else if (r == RET_PF_EMULATE) 305 vcpu->stat.pf_emulate++; 306 else if (r == RET_PF_SPURIOUS) 307 vcpu->stat.pf_spurious++; 308 return r; 309 } 310 311 int kvm_mmu_max_mapping_level(struct kvm *kvm, 312 const struct kvm_memory_slot *slot, gfn_t gfn, 313 int max_level); 314 void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); 315 void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_level); 316 317 void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc); 318 319 void track_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp); 320 void untrack_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp); 321 322 #endif /* __KVM_X86_MMU_INTERNAL_H */ 323