arch/mips/kvm/mmu.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * KVM/MIPS MMU handling in the KVM module.
   7  *
   8  * Copyright (C) 2012  MIPS Technologies, Inc.  All rights reserved.
   9  * Authors: Sanjay Lal <sanjayl@kymasys.com>
  10  */
  11
  12 #include <linux/highmem.h>
  13 #include <linux/kvm_host.h>
  14 #include <linux/uaccess.h>
  15 #include <asm/mmu_context.h>
  16 #include <asm/pgalloc.h>
  17
  18 /*
  19  * KVM_MMU_CACHE_MIN_PAGES is the number of GPA page table translation levels
  20  * for which pages need to be cached.
  21  */
  22 #if defined(__PAGETABLE_PMD_FOLDED)
  23 #define KVM_MMU_CACHE_MIN_PAGES 1
  24 #else
  25 #define KVM_MMU_CACHE_MIN_PAGES 2
  26 #endif
  27
  28 static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
  29                                   int min, int max)
  30 {
  31         void *page;
  32
  33         BUG_ON(max > KVM_NR_MEM_OBJS);
  34         if (cache->nobjs >= min)
  35                 return 0;
  36         while (cache->nobjs < max) {
  37                 page = (void *)__get_free_page(GFP_KERNEL);
  38                 if (!page)
  39                         return -ENOMEM;
  40                 cache->objects[cache->nobjs++] = page;
  41         }
  42         return 0;
  43 }
  44
  45 static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
  46 {
  47         while (mc->nobjs)
  48                 free_page((unsigned long)mc->objects[--mc->nobjs]);
  49 }
  50
  51 static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
  52 {
  53         void *p;
  54
  55         BUG_ON(!mc || !mc->nobjs);
  56         p = mc->objects[--mc->nobjs];
  57         return p;
  58 }
  59
  60 void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu)
  61 {
  62         mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
  63 }
  64
  65 /**
  66  * kvm_pgd_init() - Initialise KVM GPA page directory.
  67  * @page:       Pointer to page directory (PGD) for KVM GPA.
  68  *
  69  * Initialise a KVM GPA page directory with pointers to the invalid table, i.e.
  70  * representing no mappings. This is similar to pgd_init(), however it
  71  * initialises all the page directory pointers, not just the ones corresponding
  72  * to the userland address space (since it is for the guest physical address
  73  * space rather than a virtual address space).
  74  */
  75 static void kvm_pgd_init(void *page)
  76 {
  77         unsigned long *p, *end;
  78         unsigned long entry;
  79
  80 #ifdef __PAGETABLE_PMD_FOLDED
  81         entry = (unsigned long)invalid_pte_table;
  82 #else
  83         entry = (unsigned long)invalid_pmd_table;
  84 #endif
  85
  86         p = (unsigned long *)page;
  87         end = p + PTRS_PER_PGD;
  88
  89         do {
  90                 p[0] = entry;
  91                 p[1] = entry;
  92                 p[2] = entry;
  93                 p[3] = entry;
  94                 p[4] = entry;
  95                 p += 8;
  96                 p[-3] = entry;
  97                 p[-2] = entry;
  98                 p[-1] = entry;
  99         } while (p != end);
 100 }
 101
 102 /**
 103  * kvm_pgd_alloc() - Allocate and initialise a KVM GPA page directory.
 104  *
 105  * Allocate a blank KVM GPA page directory (PGD) for representing guest physical
 106  * to host physical page mappings.
 107  *
 108  * Returns:     Pointer to new KVM GPA page directory.
 109  *              NULL on allocation failure.
 110  */
 111 pgd_t *kvm_pgd_alloc(void)
 112 {
 113         pgd_t *ret;
 114
 115         ret = (pgd_t *)__get_free_pages(GFP_KERNEL, PGD_ORDER);
 116         if (ret)
 117                 kvm_pgd_init(ret);
 118
 119         return ret;
 120 }
 121
 122 /**
 123  * kvm_mips_walk_pgd() - Walk page table with optional allocation.
 124  * @pgd:        Page directory pointer.
 125  * @addr:       Address to index page table using.
 126  * @cache:      MMU page cache to allocate new page tables from, or NULL.
 127  *
 128  * Walk the page tables pointed to by @pgd to find the PTE corresponding to the
 129  * address @addr. If page tables don't exist for @addr, they will be created
 130  * from the MMU cache if @cache is not NULL.
 131  *
 132  * Returns:     Pointer to pte_t corresponding to @addr.
 133  *              NULL if a page table doesn't exist for @addr and !@cache.
 134  *              NULL if a page table allocation failed.
 135  */
 136 static pte_t *kvm_mips_walk_pgd(pgd_t *pgd, struct kvm_mmu_memory_cache *cache,
 137                                 unsigned long addr)
 138 {
 139         pud_t *pud;
 140         pmd_t *pmd;
 141
 142         pgd += pgd_index(addr);
 143         if (pgd_none(*pgd)) {
 144                 /* Not used on MIPS yet */
 145                 BUG();
 146                 return NULL;
 147         }
 148         pud = pud_offset(pgd, addr);
 149         if (pud_none(*pud)) {
 150                 pmd_t *new_pmd;
 151
 152                 if (!cache)
 153                         return NULL;
 154                 new_pmd = mmu_memory_cache_alloc(cache);
 155                 pmd_init((unsigned long)new_pmd,
 156                          (unsigned long)invalid_pte_table);
 157                 pud_populate(NULL, pud, new_pmd);
 158         }
 159         pmd = pmd_offset(pud, addr);
 160         if (pmd_none(*pmd)) {
 161                 pte_t *new_pte;
 162
 163                 if (!cache)
 164                         return NULL;
 165                 new_pte = mmu_memory_cache_alloc(cache);
 166                 clear_page(new_pte);
 167                 pmd_populate_kernel(NULL, pmd, new_pte);
 168         }
 169         return pte_offset(pmd, addr);
 170 }
 171
 172 /* Caller must hold kvm->mm_lock */
 173 static pte_t *kvm_mips_pte_for_gpa(struct kvm *kvm,
 174                                    struct kvm_mmu_memory_cache *cache,
 175                                    unsigned long addr)
 176 {
 177         return kvm_mips_walk_pgd(kvm->arch.gpa_mm.pgd, cache, addr);
 178 }
 179
 180 /*
 181  * kvm_mips_flush_gpa_{pte,pmd,pud,pgd,pt}.
 182  * Flush a range of guest physical address space from the VM's GPA page tables.
 183  */
 184
 185 static bool kvm_mips_flush_gpa_pte(pte_t *pte, unsigned long start_gpa,
 186                                    unsigned long end_gpa)
 187 {
 188         int i_min = __pte_offset(start_gpa);
 189         int i_max = __pte_offset(end_gpa);
 190         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PTE - 1);
 191         int i;
 192
 193         for (i = i_min; i <= i_max; ++i) {
 194                 if (!pte_present(pte[i]))
 195                         continue;
 196
 197                 set_pte(pte + i, __pte(0));
 198         }
 199         return safe_to_remove;
 200 }
 201
 202 static bool kvm_mips_flush_gpa_pmd(pmd_t *pmd, unsigned long start_gpa,
 203                                    unsigned long end_gpa)
 204 {
 205         pte_t *pte;
 206         unsigned long end = ~0ul;
 207         int i_min = __pmd_offset(start_gpa);
 208         int i_max = __pmd_offset(end_gpa);
 209         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PMD - 1);
 210         int i;
 211
 212         for (i = i_min; i <= i_max; ++i, start_gpa = 0) {
 213                 if (!pmd_present(pmd[i]))
 214                         continue;
 215
 216                 pte = pte_offset(pmd + i, 0);
 217                 if (i == i_max)
 218                         end = end_gpa;
 219
 220                 if (kvm_mips_flush_gpa_pte(pte, start_gpa, end)) {
 221                         pmd_clear(pmd + i);
 222                         pte_free_kernel(NULL, pte);
 223                 } else {
 224                         safe_to_remove = false;
 225                 }
 226         }
 227         return safe_to_remove;
 228 }
 229
 230 static bool kvm_mips_flush_gpa_pud(pud_t *pud, unsigned long start_gpa,
 231                                    unsigned long end_gpa)
 232 {
 233         pmd_t *pmd;
 234         unsigned long end = ~0ul;
 235         int i_min = __pud_offset(start_gpa);
 236         int i_max = __pud_offset(end_gpa);
 237         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PUD - 1);
 238         int i;
 239
 240         for (i = i_min; i <= i_max; ++i, start_gpa = 0) {
 241                 if (!pud_present(pud[i]))
 242                         continue;
 243
 244                 pmd = pmd_offset(pud + i, 0);
 245                 if (i == i_max)
 246                         end = end_gpa;
 247
 248                 if (kvm_mips_flush_gpa_pmd(pmd, start_gpa, end)) {
 249                         pud_clear(pud + i);
 250                         pmd_free(NULL, pmd);
 251                 } else {
 252                         safe_to_remove = false;
 253                 }
 254         }
 255         return safe_to_remove;
 256 }
 257
 258 static bool kvm_mips_flush_gpa_pgd(pgd_t *pgd, unsigned long start_gpa,
 259                                    unsigned long end_gpa)
 260 {
 261         pud_t *pud;
 262         unsigned long end = ~0ul;
 263         int i_min = pgd_index(start_gpa);
 264         int i_max = pgd_index(end_gpa);
 265         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PGD - 1);
 266         int i;
 267
 268         for (i = i_min; i <= i_max; ++i, start_gpa = 0) {
 269                 if (!pgd_present(pgd[i]))
 270                         continue;
 271
 272                 pud = pud_offset(pgd + i, 0);
 273                 if (i == i_max)
 274                         end = end_gpa;
 275
 276                 if (kvm_mips_flush_gpa_pud(pud, start_gpa, end)) {
 277                         pgd_clear(pgd + i);
 278                         pud_free(NULL, pud);
 279                 } else {
 280                         safe_to_remove = false;
 281                 }
 282         }
 283         return safe_to_remove;
 284 }
 285
 286 /**
 287  * kvm_mips_flush_gpa_pt() - Flush a range of guest physical addresses.
 288  * @kvm:        KVM pointer.
 289  * @start_gfn:  Guest frame number of first page in GPA range to flush.
 290  * @end_gfn:    Guest frame number of last page in GPA range to flush.
 291  *
 292  * Flushes a range of GPA mappings from the GPA page tables.
 293  *
 294  * The caller must hold the @kvm->mmu_lock spinlock.
 295  *
 296  * Returns:     Whether its safe to remove the top level page directory because
 297  *              all lower levels have been removed.
 298  */
 299 bool kvm_mips_flush_gpa_pt(struct kvm *kvm, gfn_t start_gfn, gfn_t end_gfn)
 300 {
 301         return kvm_mips_flush_gpa_pgd(kvm->arch.gpa_mm.pgd,
 302                                       start_gfn << PAGE_SHIFT,
 303                                       end_gfn << PAGE_SHIFT);
 304 }
 305
 306 #define BUILD_PTE_RANGE_OP(name, op)                                    \
 307 static int kvm_mips_##name##_pte(pte_t *pte, unsigned long start,       \
 308                                  unsigned long end)                     \
 309 {                                                                       \
 310         int ret = 0;                                                    \
 311         int i_min = __pte_offset(start);                                \
 312         int i_max = __pte_offset(end);                                  \
 313         int i;                                                          \
 314         pte_t old, new;                                                 \
 315                                                                         \
 316         for (i = i_min; i <= i_max; ++i) {                              \
 317                 if (!pte_present(pte[i]))                               \
 318                         continue;                                       \
 319                                                                         \
 320                 old = pte[i];                                           \
 321                 new = op(old);                                          \
 322                 if (pte_val(new) == pte_val(old))                       \
 323                         continue;                                       \
 324                 set_pte(pte + i, new);                                  \
 325                 ret = 1;                                                \
 326         }                                                               \
 327         return ret;                                                     \
 328 }                                                                       \
 329                                                                         \
 330 /* returns true if anything was done */                                 \
 331 static int kvm_mips_##name##_pmd(pmd_t *pmd, unsigned long start,       \
 332                                  unsigned long end)                     \
 333 {                                                                       \
 334         int ret = 0;                                                    \
 335         pte_t *pte;                                                     \
 336         unsigned long cur_end = ~0ul;                                   \
 337         int i_min = __pmd_offset(start);                                \
 338         int i_max = __pmd_offset(end);                                  \
 339         int i;                                                          \
 340                                                                         \
 341         for (i = i_min; i <= i_max; ++i, start = 0) {                   \
 342                 if (!pmd_present(pmd[i]))                               \
 343                         continue;                                       \
 344                                                                         \
 345                 pte = pte_offset(pmd + i, 0);                           \
 346                 if (i == i_max)                                         \
 347                         cur_end = end;                                  \
 348                                                                         \
 349                 ret |= kvm_mips_##name##_pte(pte, start, cur_end);      \
 350         }                                                               \
 351         return ret;                                                     \
 352 }                                                                       \
 353                                                                         \
 354 static int kvm_mips_##name##_pud(pud_t *pud, unsigned long start,       \
 355                                  unsigned long end)                     \
 356 {                                                                       \
 357         int ret = 0;                                                    \
 358         pmd_t *pmd;                                                     \
 359         unsigned long cur_end = ~0ul;                                   \
 360         int i_min = __pud_offset(start);                                \
 361         int i_max = __pud_offset(end);                                  \
 362         int i;                                                          \
 363                                                                         \
 364         for (i = i_min; i <= i_max; ++i, start = 0) {                   \
 365                 if (!pud_present(pud[i]))                               \
 366                         continue;                                       \
 367                                                                         \
 368                 pmd = pmd_offset(pud + i, 0);                           \
 369                 if (i == i_max)                                         \
 370                         cur_end = end;                                  \
 371                                                                         \
 372                 ret |= kvm_mips_##name##_pmd(pmd, start, cur_end);      \
 373         }                                                               \
 374         return ret;                                                     \
 375 }                                                                       \
 376                                                                         \
 377 static int kvm_mips_##name##_pgd(pgd_t *pgd, unsigned long start,       \
 378                                  unsigned long end)                     \
 379 {                                                                       \
 380         int ret = 0;                                                    \
 381         pud_t *pud;                                                     \
 382         unsigned long cur_end = ~0ul;                                   \
 383         int i_min = pgd_index(start);                                   \
 384         int i_max = pgd_index(end);                                     \
 385         int i;                                                          \
 386                                                                         \
 387         for (i = i_min; i <= i_max; ++i, start = 0) {                   \
 388                 if (!pgd_present(pgd[i]))                               \
 389                         continue;                                       \
 390                                                                         \
 391                 pud = pud_offset(pgd + i, 0);                           \
 392                 if (i == i_max)                                         \
 393                         cur_end = end;                                  \
 394                                                                         \
 395                 ret |= kvm_mips_##name##_pud(pud, start, cur_end);      \
 396         }                                                               \
 397         return ret;                                                     \
 398 }
 399
 400 /*
 401  * kvm_mips_mkclean_gpa_pt.
 402  * Mark a range of guest physical address space clean (writes fault) in the VM's
 403  * GPA page table to allow dirty page tracking.
 404  */
 405
 406 BUILD_PTE_RANGE_OP(mkclean, pte_mkclean)
 407
 408 /**
 409  * kvm_mips_mkclean_gpa_pt() - Make a range of guest physical addresses clean.
 410  * @kvm:        KVM pointer.
 411  * @start_gfn:  Guest frame number of first page in GPA range to flush.
 412  * @end_gfn:    Guest frame number of last page in GPA range to flush.
 413  *
 414  * Make a range of GPA mappings clean so that guest writes will fault and
 415  * trigger dirty page logging.
 416  *
 417  * The caller must hold the @kvm->mmu_lock spinlock.
 418  *
 419  * Returns:     Whether any GPA mappings were modified, which would require
 420  *              derived mappings (GVA page tables & TLB enties) to be
 421  *              invalidated.
 422  */
 423 int kvm_mips_mkclean_gpa_pt(struct kvm *kvm, gfn_t start_gfn, gfn_t end_gfn)
 424 {
 425         return kvm_mips_mkclean_pgd(kvm->arch.gpa_mm.pgd,
 426                                     start_gfn << PAGE_SHIFT,
 427                                     end_gfn << PAGE_SHIFT);
 428 }
 429
 430 /**
 431  * kvm_arch_mmu_enable_log_dirty_pt_masked() - write protect dirty pages
 432  * @kvm:        The KVM pointer
 433  * @slot:       The memory slot associated with mask
 434  * @gfn_offset: The gfn offset in memory slot
 435  * @mask:       The mask of dirty pages at offset 'gfn_offset' in this memory
 436  *              slot to be write protected
 437  *
 438  * Walks bits set in mask write protects the associated pte's. Caller must
 439  * acquire @kvm->mmu_lock.
 440  */
 441 void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
 442                 struct kvm_memory_slot *slot,
 443                 gfn_t gfn_offset, unsigned long mask)
 444 {
 445         gfn_t base_gfn = slot->base_gfn + gfn_offset;
 446         gfn_t start = base_gfn +  __ffs(mask);
 447         gfn_t end = base_gfn + __fls(mask);
 448
 449         kvm_mips_mkclean_gpa_pt(kvm, start, end);
 450 }
 451
 452 /*
 453  * kvm_mips_mkold_gpa_pt.
 454  * Mark a range of guest physical address space old (all accesses fault) in the
 455  * VM's GPA page table to allow detection of commonly used pages.
 456  */
 457
 458 BUILD_PTE_RANGE_OP(mkold, pte_mkold)
 459
 460 static int kvm_mips_mkold_gpa_pt(struct kvm *kvm, gfn_t start_gfn,
 461                                  gfn_t end_gfn)
 462 {
 463         return kvm_mips_mkold_pgd(kvm->arch.gpa_mm.pgd,
 464                                   start_gfn << PAGE_SHIFT,
 465                                   end_gfn << PAGE_SHIFT);
 466 }
 467
 468 static int handle_hva_to_gpa(struct kvm *kvm,
 469                              unsigned long start,
 470                              unsigned long end,
 471                              int (*handler)(struct kvm *kvm, gfn_t gfn,
 472                                             gpa_t gfn_end,
 473                                             struct kvm_memory_slot *memslot,
 474                                             void *data),
 475                              void *data)
 476 {
 477         struct kvm_memslots *slots;
 478         struct kvm_memory_slot *memslot;
 479         int ret = 0;
 480
 481         slots = kvm_memslots(kvm);
 482
 483         /* we only care about the pages that the guest sees */
 484         kvm_for_each_memslot(memslot, slots) {
 485                 unsigned long hva_start, hva_end;
 486                 gfn_t gfn, gfn_end;
 487
 488                 hva_start = max(start, memslot->userspace_addr);
 489                 hva_end = min(end, memslot->userspace_addr +
 490                                         (memslot->npages << PAGE_SHIFT));
 491                 if (hva_start >= hva_end)
 492                         continue;
 493
 494                 /*
 495                  * {gfn(page) | page intersects with [hva_start, hva_end)} =
 496                  * {gfn_start, gfn_start+1, ..., gfn_end-1}.
 497                  */
 498                 gfn = hva_to_gfn_memslot(hva_start, memslot);
 499                 gfn_end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, memslot);
 500
 501                 ret |= handler(kvm, gfn, gfn_end, memslot, data);
 502         }
 503
 504         return ret;
 505 }
 506
 507
 508 static int kvm_unmap_hva_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end,
 509                                  struct kvm_memory_slot *memslot, void *data)
 510 {
 511         kvm_mips_flush_gpa_pt(kvm, gfn, gfn_end);
 512         return 1;
 513 }
 514
 515 int kvm_unmap_hva(struct kvm *kvm, unsigned long hva)
 516 {
 517         unsigned long end = hva + PAGE_SIZE;
 518
 519         handle_hva_to_gpa(kvm, hva, end, &kvm_unmap_hva_handler, NULL);
 520
 521         kvm_mips_callbacks->flush_shadow_all(kvm);
 522         return 0;
 523 }
 524
 525 int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end)
 526 {
 527         handle_hva_to_gpa(kvm, start, end, &kvm_unmap_hva_handler, NULL);
 528
 529         kvm_mips_callbacks->flush_shadow_all(kvm);
 530         return 0;
 531 }
 532
 533 static int kvm_set_spte_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end,
 534                                 struct kvm_memory_slot *memslot, void *data)
 535 {
 536         gpa_t gpa = gfn << PAGE_SHIFT;
 537         pte_t hva_pte = *(pte_t *)data;
 538         pte_t *gpa_pte = kvm_mips_pte_for_gpa(kvm, NULL, gpa);
 539         pte_t old_pte;
 540
 541         if (!gpa_pte)
 542                 return 0;
 543
 544         /* Mapping may need adjusting depending on memslot flags */
 545         old_pte = *gpa_pte;
 546         if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES && !pte_dirty(old_pte))
 547                 hva_pte = pte_mkclean(hva_pte);
 548         else if (memslot->flags & KVM_MEM_READONLY)
 549                 hva_pte = pte_wrprotect(hva_pte);
 550
 551         set_pte(gpa_pte, hva_pte);
 552
 553         /* Replacing an absent or old page doesn't need flushes */
 554         if (!pte_present(old_pte) || !pte_young(old_pte))
 555                 return 0;
 556
 557         /* Pages swapped, aged, moved, or cleaned require flushes */
 558         return !pte_present(hva_pte) ||
 559                !pte_young(hva_pte) ||
 560                pte_pfn(old_pte) != pte_pfn(hva_pte) ||
 561                (pte_dirty(old_pte) && !pte_dirty(hva_pte));
 562 }
 563
 564 void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
 565 {
 566         unsigned long end = hva + PAGE_SIZE;
 567         int ret;
 568
 569         ret = handle_hva_to_gpa(kvm, hva, end, &kvm_set_spte_handler, &pte);
 570         if (ret)
 571                 kvm_mips_callbacks->flush_shadow_all(kvm);
 572 }
 573
 574 static int kvm_age_hva_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end,
 575                                struct kvm_memory_slot *memslot, void *data)
 576 {
 577         return kvm_mips_mkold_gpa_pt(kvm, gfn, gfn_end);
 578 }
 579
 580 static int kvm_test_age_hva_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end,
 581                                     struct kvm_memory_slot *memslot, void *data)
 582 {
 583         gpa_t gpa = gfn << PAGE_SHIFT;
 584         pte_t *gpa_pte = kvm_mips_pte_for_gpa(kvm, NULL, gpa);
 585
 586         if (!gpa_pte)
 587                 return 0;
 588         return pte_young(*gpa_pte);
 589 }
 590
 591 int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end)
 592 {
 593         return handle_hva_to_gpa(kvm, start, end, kvm_age_hva_handler, NULL);
 594 }
 595
 596 int kvm_test_age_hva(struct kvm *kvm, unsigned long hva)
 597 {
 598         return handle_hva_to_gpa(kvm, hva, hva, kvm_test_age_hva_handler, NULL);
 599 }
 600
 601 /**
 602  * _kvm_mips_map_page_fast() - Fast path GPA fault handler.
 603  * @vcpu:               VCPU pointer.
 604  * @gpa:                Guest physical address of fault.
 605  * @write_fault:        Whether the fault was due to a write.
 606  * @out_entry:          New PTE for @gpa (written on success unless NULL).
 607  * @out_buddy:          New PTE for @gpa's buddy (written on success unless
 608  *                      NULL).
 609  *
 610  * Perform fast path GPA fault handling, doing all that can be done without
 611  * calling into KVM. This handles marking old pages young (for idle page
 612  * tracking), and dirtying of clean pages (for dirty page logging).
 613  *
 614  * Returns:     0 on success, in which case we can update derived mappings and
 615  *              resume guest execution.
 616  *              -EFAULT on failure due to absent GPA mapping or write to
 617  *              read-only page, in which case KVM must be consulted.
 618  */
 619 static int _kvm_mips_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa,
 620                                    bool write_fault,
 621                                    pte_t *out_entry, pte_t *out_buddy)
 622 {
 623         struct kvm *kvm = vcpu->kvm;
 624         gfn_t gfn = gpa >> PAGE_SHIFT;
 625         pte_t *ptep;
 626         kvm_pfn_t pfn = 0;      /* silence bogus GCC warning */
 627         bool pfn_valid = false;
 628         int ret = 0;
 629
 630         spin_lock(&kvm->mmu_lock);
 631
 632         /* Fast path - just check GPA page table for an existing entry */
 633         ptep = kvm_mips_pte_for_gpa(kvm, NULL, gpa);
 634         if (!ptep || !pte_present(*ptep)) {
 635                 ret = -EFAULT;
 636                 goto out;
 637         }
 638
 639         /* Track access to pages marked old */
 640         if (!pte_young(*ptep)) {
 641                 set_pte(ptep, pte_mkyoung(*ptep));
 642                 pfn = pte_pfn(*ptep);
 643                 pfn_valid = true;
 644                 /* call kvm_set_pfn_accessed() after unlock */
 645         }
 646         if (write_fault && !pte_dirty(*ptep)) {
 647                 if (!pte_write(*ptep)) {
 648                         ret = -EFAULT;
 649                         goto out;
 650                 }
 651
 652                 /* Track dirtying of writeable pages */
 653                 set_pte(ptep, pte_mkdirty(*ptep));
 654                 pfn = pte_pfn(*ptep);
 655                 mark_page_dirty(kvm, gfn);
 656                 kvm_set_pfn_dirty(pfn);
 657         }
 658
 659         if (out_entry)
 660                 *out_entry = *ptep;
 661         if (out_buddy)
 662                 *out_buddy = *ptep_buddy(ptep);
 663
 664 out:
 665         spin_unlock(&kvm->mmu_lock);
 666         if (pfn_valid)
 667                 kvm_set_pfn_accessed(pfn);
 668         return ret;
 669 }
 670
 671 /**
 672  * kvm_mips_map_page() - Map a guest physical page.
 673  * @vcpu:               VCPU pointer.
 674  * @gpa:                Guest physical address of fault.
 675  * @write_fault:        Whether the fault was due to a write.
 676  * @out_entry:          New PTE for @gpa (written on success unless NULL).
 677  * @out_buddy:          New PTE for @gpa's buddy (written on success unless
 678  *                      NULL).
 679  *
 680  * Handle GPA faults by creating a new GPA mapping (or updating an existing
 681  * one).
 682  *
 683  * This takes care of marking pages young or dirty (idle/dirty page tracking),
 684  * asking KVM for the corresponding PFN, and creating a mapping in the GPA page
 685  * tables. Derived mappings (GVA page tables and TLBs) must be handled by the
 686  * caller.
 687  *
 688  * Returns:     0 on success, in which case the caller may use the @out_entry
 689  *              and @out_buddy PTEs to update derived mappings and resume guest
 690  *              execution.
 691  *              -EFAULT if there is no memory region at @gpa or a write was
 692  *              attempted to a read-only memory region. This is usually handled
 693  *              as an MMIO access.
 694  */
 695 static int kvm_mips_map_page(struct kvm_vcpu *vcpu, unsigned long gpa,
 696                              bool write_fault,
 697                              pte_t *out_entry, pte_t *out_buddy)
 698 {
 699         struct kvm *kvm = vcpu->kvm;
 700         struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
 701         gfn_t gfn = gpa >> PAGE_SHIFT;
 702         int srcu_idx, err;
 703         kvm_pfn_t pfn;
 704         pte_t *ptep, entry, old_pte;
 705         bool writeable;
 706         unsigned long prot_bits;
 707         unsigned long mmu_seq;
 708
 709         /* Try the fast path to handle old / clean pages */
 710         srcu_idx = srcu_read_lock(&kvm->srcu);
 711         err = _kvm_mips_map_page_fast(vcpu, gpa, write_fault, out_entry,
 712                                       out_buddy);
 713         if (!err)
 714                 goto out;
 715
 716         /* We need a minimum of cached pages ready for page table creation */
 717         err = mmu_topup_memory_cache(memcache, KVM_MMU_CACHE_MIN_PAGES,
 718                                      KVM_NR_MEM_OBJS);
 719         if (err)
 720                 goto out;
 721
 722 retry:
 723         /*
 724          * Used to check for invalidations in progress, of the pfn that is
 725          * returned by pfn_to_pfn_prot below.
 726          */
 727         mmu_seq = kvm->mmu_notifier_seq;
 728         /*
 729          * Ensure the read of mmu_notifier_seq isn't reordered with PTE reads in
 730          * gfn_to_pfn_prot() (which calls get_user_pages()), so that we don't
 731          * risk the page we get a reference to getting unmapped before we have a
 732          * chance to grab the mmu_lock without mmu_notifier_retry() noticing.
 733          *
 734          * This smp_rmb() pairs with the effective smp_wmb() of the combination
 735          * of the pte_unmap_unlock() after the PTE is zapped, and the
 736          * spin_lock() in kvm_mmu_notifier_invalidate_<page|range_end>() before
 737          * mmu_notifier_seq is incremented.
 738          */
 739         smp_rmb();
 740
 741         /* Slow path - ask KVM core whether we can access this GPA */
 742         pfn = gfn_to_pfn_prot(kvm, gfn, write_fault, &writeable);
 743         if (is_error_noslot_pfn(pfn)) {
 744                 err = -EFAULT;
 745                 goto out;
 746         }
 747
 748         spin_lock(&kvm->mmu_lock);
 749         /* Check if an invalidation has taken place since we got pfn */
 750         if (mmu_notifier_retry(kvm, mmu_seq)) {
 751                 /*
 752                  * This can happen when mappings are changed asynchronously, but
 753                  * also synchronously if a COW is triggered by
 754                  * gfn_to_pfn_prot().
 755                  */
 756                 spin_unlock(&kvm->mmu_lock);
 757                 kvm_release_pfn_clean(pfn);
 758                 goto retry;
 759         }
 760
 761         /* Ensure page tables are allocated */
 762         ptep = kvm_mips_pte_for_gpa(kvm, memcache, gpa);
 763
 764         /* Set up the PTE */
 765         prot_bits = _PAGE_PRESENT | __READABLE | _page_cachable_default;
 766         if (writeable) {
 767                 prot_bits |= _PAGE_WRITE;
 768                 if (write_fault) {
 769                         prot_bits |= __WRITEABLE;
 770                         mark_page_dirty(kvm, gfn);
 771                         kvm_set_pfn_dirty(pfn);
 772                 }
 773         }
 774         entry = pfn_pte(pfn, __pgprot(prot_bits));
 775
 776         /* Write the PTE */
 777         old_pte = *ptep;
 778         set_pte(ptep, entry);
 779
 780         err = 0;
 781         if (out_entry)
 782                 *out_entry = *ptep;
 783         if (out_buddy)
 784                 *out_buddy = *ptep_buddy(ptep);
 785
 786         spin_unlock(&kvm->mmu_lock);
 787         kvm_release_pfn_clean(pfn);
 788         kvm_set_pfn_accessed(pfn);
 789 out:
 790         srcu_read_unlock(&kvm->srcu, srcu_idx);
 791         return err;
 792 }
 793
 794 static pte_t *kvm_trap_emul_pte_for_gva(struct kvm_vcpu *vcpu,
 795                                         unsigned long addr)
 796 {
 797         struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
 798         pgd_t *pgdp;
 799         int ret;
 800
 801         /* We need a minimum of cached pages ready for page table creation */
 802         ret = mmu_topup_memory_cache(memcache, KVM_MMU_CACHE_MIN_PAGES,
 803                                      KVM_NR_MEM_OBJS);
 804         if (ret)
 805                 return NULL;
 806
 807         if (KVM_GUEST_KERNEL_MODE(vcpu))
 808                 pgdp = vcpu->arch.guest_kernel_mm.pgd;
 809         else
 810                 pgdp = vcpu->arch.guest_user_mm.pgd;
 811
 812         return kvm_mips_walk_pgd(pgdp, memcache, addr);
 813 }
 814
 815 void kvm_trap_emul_invalidate_gva(struct kvm_vcpu *vcpu, unsigned long addr,
 816                                   bool user)
 817 {
 818         pgd_t *pgdp;
 819         pte_t *ptep;
 820
 821         addr &= PAGE_MASK << 1;
 822
 823         pgdp = vcpu->arch.guest_kernel_mm.pgd;
 824         ptep = kvm_mips_walk_pgd(pgdp, NULL, addr);
 825         if (ptep) {
 826                 ptep[0] = pfn_pte(0, __pgprot(0));
 827                 ptep[1] = pfn_pte(0, __pgprot(0));
 828         }
 829
 830         if (user) {
 831                 pgdp = vcpu->arch.guest_user_mm.pgd;
 832                 ptep = kvm_mips_walk_pgd(pgdp, NULL, addr);
 833                 if (ptep) {
 834                         ptep[0] = pfn_pte(0, __pgprot(0));
 835                         ptep[1] = pfn_pte(0, __pgprot(0));
 836                 }
 837         }
 838 }
 839
 840 /*
 841  * kvm_mips_flush_gva_{pte,pmd,pud,pgd,pt}.
 842  * Flush a range of guest physical address space from the VM's GPA page tables.
 843  */
 844
 845 static bool kvm_mips_flush_gva_pte(pte_t *pte, unsigned long start_gva,
 846                                    unsigned long end_gva)
 847 {
 848         int i_min = __pte_offset(start_gva);
 849         int i_max = __pte_offset(end_gva);
 850         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PTE - 1);
 851         int i;
 852
 853         /*
 854          * There's no freeing to do, so there's no point clearing individual
 855          * entries unless only part of the last level page table needs flushing.
 856          */
 857         if (safe_to_remove)
 858                 return true;
 859
 860         for (i = i_min; i <= i_max; ++i) {
 861                 if (!pte_present(pte[i]))
 862                         continue;
 863
 864                 set_pte(pte + i, __pte(0));
 865         }
 866         return false;
 867 }
 868
 869 static bool kvm_mips_flush_gva_pmd(pmd_t *pmd, unsigned long start_gva,
 870                                    unsigned long end_gva)
 871 {
 872         pte_t *pte;
 873         unsigned long end = ~0ul;
 874         int i_min = __pmd_offset(start_gva);
 875         int i_max = __pmd_offset(end_gva);
 876         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PMD - 1);
 877         int i;
 878
 879         for (i = i_min; i <= i_max; ++i, start_gva = 0) {
 880                 if (!pmd_present(pmd[i]))
 881                         continue;
 882
 883                 pte = pte_offset(pmd + i, 0);
 884                 if (i == i_max)
 885                         end = end_gva;
 886
 887                 if (kvm_mips_flush_gva_pte(pte, start_gva, end)) {
 888                         pmd_clear(pmd + i);
 889                         pte_free_kernel(NULL, pte);
 890                 } else {
 891                         safe_to_remove = false;
 892                 }
 893         }
 894         return safe_to_remove;
 895 }
 896
 897 static bool kvm_mips_flush_gva_pud(pud_t *pud, unsigned long start_gva,
 898                                    unsigned long end_gva)
 899 {
 900         pmd_t *pmd;
 901         unsigned long end = ~0ul;
 902         int i_min = __pud_offset(start_gva);
 903         int i_max = __pud_offset(end_gva);
 904         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PUD - 1);
 905         int i;
 906
 907         for (i = i_min; i <= i_max; ++i, start_gva = 0) {
 908                 if (!pud_present(pud[i]))
 909                         continue;
 910
 911                 pmd = pmd_offset(pud + i, 0);
 912                 if (i == i_max)
 913                         end = end_gva;
 914
 915                 if (kvm_mips_flush_gva_pmd(pmd, start_gva, end)) {
 916                         pud_clear(pud + i);
 917                         pmd_free(NULL, pmd);
 918                 } else {
 919                         safe_to_remove = false;
 920                 }
 921         }
 922         return safe_to_remove;
 923 }
 924
 925 static bool kvm_mips_flush_gva_pgd(pgd_t *pgd, unsigned long start_gva,
 926                                    unsigned long end_gva)
 927 {
 928         pud_t *pud;
 929         unsigned long end = ~0ul;
 930         int i_min = pgd_index(start_gva);
 931         int i_max = pgd_index(end_gva);
 932         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PGD - 1);
 933         int i;
 934
 935         for (i = i_min; i <= i_max; ++i, start_gva = 0) {
 936                 if (!pgd_present(pgd[i]))
 937                         continue;
 938
 939                 pud = pud_offset(pgd + i, 0);
 940                 if (i == i_max)
 941                         end = end_gva;
 942
 943                 if (kvm_mips_flush_gva_pud(pud, start_gva, end)) {
 944                         pgd_clear(pgd + i);
 945                         pud_free(NULL, pud);
 946                 } else {
 947                         safe_to_remove = false;
 948                 }
 949         }
 950         return safe_to_remove;
 951 }
 952
 953 void kvm_mips_flush_gva_pt(pgd_t *pgd, enum kvm_mips_flush flags)
 954 {
 955         if (flags & KMF_GPA) {
 956                 /* all of guest virtual address space could be affected */
 957                 if (flags & KMF_KERN)
 958                         /* useg, kseg0, seg2/3 */
 959                         kvm_mips_flush_gva_pgd(pgd, 0, 0x7fffffff);
 960                 else
 961                         /* useg */
 962                         kvm_mips_flush_gva_pgd(pgd, 0, 0x3fffffff);
 963         } else {
 964                 /* useg */
 965                 kvm_mips_flush_gva_pgd(pgd, 0, 0x3fffffff);
 966
 967                 /* kseg2/3 */
 968                 if (flags & KMF_KERN)
 969                         kvm_mips_flush_gva_pgd(pgd, 0x60000000, 0x7fffffff);
 970         }
 971 }
 972
 973 static pte_t kvm_mips_gpa_pte_to_gva_unmapped(pte_t pte)
 974 {
 975         /*
 976          * Don't leak writeable but clean entries from GPA page tables. We don't
 977          * want the normal Linux tlbmod handler to handle dirtying when KVM
 978          * accesses guest memory.
 979          */
 980         if (!pte_dirty(pte))
 981                 pte = pte_wrprotect(pte);
 982
 983         return pte;
 984 }
 985
 986 static pte_t kvm_mips_gpa_pte_to_gva_mapped(pte_t pte, long entrylo)
 987 {
 988         /* Guest EntryLo overrides host EntryLo */
 989         if (!(entrylo & ENTRYLO_D))
 990                 pte = pte_mkclean(pte);
 991
 992         return kvm_mips_gpa_pte_to_gva_unmapped(pte);
 993 }
 994
 995 #ifdef CONFIG_KVM_MIPS_VZ
 996 int kvm_mips_handle_vz_root_tlb_fault(unsigned long badvaddr,
 997                                       struct kvm_vcpu *vcpu,
 998                                       bool write_fault)
 999 {
1000         int ret;
1001
1002         ret = kvm_mips_map_page(vcpu, badvaddr, write_fault, NULL, NULL);
1003         if (ret)
1004                 return ret;
1005
1006         /* Invalidate this entry in the TLB */
1007         return kvm_vz_host_tlb_inv(vcpu, badvaddr);
1008 }
1009 #endif
1010
1011 /* XXXKYMA: Must be called with interrupts disabled */
1012 int kvm_mips_handle_kseg0_tlb_fault(unsigned long badvaddr,
1013                                     struct kvm_vcpu *vcpu,
1014                                     bool write_fault)
1015 {
1016         unsigned long gpa;
1017         pte_t pte_gpa[2], *ptep_gva;
1018         int idx;
1019
1020         if (KVM_GUEST_KSEGX(badvaddr) != KVM_GUEST_KSEG0) {
1021                 kvm_err("%s: Invalid BadVaddr: %#lx\n", __func__, badvaddr);
1022                 kvm_mips_dump_host_tlbs();
1023                 return -1;
1024         }
1025
1026         /* Get the GPA page table entry */
1027         gpa = KVM_GUEST_CPHYSADDR(badvaddr);
1028         idx = (badvaddr >> PAGE_SHIFT) & 1;
1029         if (kvm_mips_map_page(vcpu, gpa, write_fault, &pte_gpa[idx],
1030                               &pte_gpa[!idx]) < 0)
1031                 return -1;
1032
1033         /* Get the GVA page table entry */
1034         ptep_gva = kvm_trap_emul_pte_for_gva(vcpu, badvaddr & ~PAGE_SIZE);
1035         if (!ptep_gva) {
1036                 kvm_err("No ptep for gva %lx\n", badvaddr);
1037                 return -1;
1038         }
1039
1040         /* Copy a pair of entries from GPA page table to GVA page table */
1041         ptep_gva[0] = kvm_mips_gpa_pte_to_gva_unmapped(pte_gpa[0]);
1042         ptep_gva[1] = kvm_mips_gpa_pte_to_gva_unmapped(pte_gpa[1]);
1043
1044         /* Invalidate this entry in the TLB, guest kernel ASID only */
1045         kvm_mips_host_tlb_inv(vcpu, badvaddr, false, true);
1046         return 0;
1047 }
1048
1049 int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu,
1050                                          struct kvm_mips_tlb *tlb,
1051                                          unsigned long gva,
1052                                          bool write_fault)
1053 {
1054         struct kvm *kvm = vcpu->kvm;
1055         long tlb_lo[2];
1056         pte_t pte_gpa[2], *ptep_buddy, *ptep_gva;
1057         unsigned int idx = TLB_LO_IDX(*tlb, gva);
1058         bool kernel = KVM_GUEST_KERNEL_MODE(vcpu);
1059
1060         tlb_lo[0] = tlb->tlb_lo[0];
1061         tlb_lo[1] = tlb->tlb_lo[1];
1062
1063         /*
1064          * The commpage address must not be mapped to anything else if the guest
1065          * TLB contains entries nearby, or commpage accesses will break.
1066          */
1067         if (!((gva ^ KVM_GUEST_COMMPAGE_ADDR) & VPN2_MASK & (PAGE_MASK << 1)))
1068                 tlb_lo[TLB_LO_IDX(*tlb, KVM_GUEST_COMMPAGE_ADDR)] = 0;
1069
1070         /* Get the GPA page table entry */
1071         if (kvm_mips_map_page(vcpu, mips3_tlbpfn_to_paddr(tlb_lo[idx]),
1072                               write_fault, &pte_gpa[idx], NULL) < 0)
1073                 return -1;
1074
1075         /* And its GVA buddy's GPA page table entry if it also exists */
1076         pte_gpa[!idx] = pfn_pte(0, __pgprot(0));
1077         if (tlb_lo[!idx] & ENTRYLO_V) {
1078                 spin_lock(&kvm->mmu_lock);
1079                 ptep_buddy = kvm_mips_pte_for_gpa(kvm, NULL,
1080                                         mips3_tlbpfn_to_paddr(tlb_lo[!idx]));
1081                 if (ptep_buddy)
1082                         pte_gpa[!idx] = *ptep_buddy;
1083                 spin_unlock(&kvm->mmu_lock);
1084         }
1085
1086         /* Get the GVA page table entry pair */
1087         ptep_gva = kvm_trap_emul_pte_for_gva(vcpu, gva & ~PAGE_SIZE);
1088         if (!ptep_gva) {
1089                 kvm_err("No ptep for gva %lx\n", gva);
1090                 return -1;
1091         }
1092
1093         /* Copy a pair of entries from GPA page table to GVA page table */
1094         ptep_gva[0] = kvm_mips_gpa_pte_to_gva_mapped(pte_gpa[0], tlb_lo[0]);
1095         ptep_gva[1] = kvm_mips_gpa_pte_to_gva_mapped(pte_gpa[1], tlb_lo[1]);
1096
1097         /* Invalidate this entry in the TLB, current guest mode ASID only */
1098         kvm_mips_host_tlb_inv(vcpu, gva, !kernel, kernel);
1099
1100         kvm_debug("@ %#lx tlb_lo0: 0x%08lx tlb_lo1: 0x%08lx\n", vcpu->arch.pc,
1101                   tlb->tlb_lo[0], tlb->tlb_lo[1]);
1102
1103         return 0;
1104 }
1105
1106 int kvm_mips_handle_commpage_tlb_fault(unsigned long badvaddr,
1107                                        struct kvm_vcpu *vcpu)
1108 {
1109         kvm_pfn_t pfn;
1110         pte_t *ptep;
1111
1112         ptep = kvm_trap_emul_pte_for_gva(vcpu, badvaddr);
1113         if (!ptep) {
1114                 kvm_err("No ptep for commpage %lx\n", badvaddr);
1115                 return -1;
1116         }
1117
1118         pfn = PFN_DOWN(virt_to_phys(vcpu->arch.kseg0_commpage));
1119         /* Also set valid and dirty, so refill handler doesn't have to */
1120         *ptep = pte_mkyoung(pte_mkdirty(pfn_pte(pfn, PAGE_SHARED)));
1121
1122         /* Invalidate this entry in the TLB, guest kernel ASID only */
1123         kvm_mips_host_tlb_inv(vcpu, badvaddr, false, true);
1124         return 0;
1125 }
1126
1127 /**
1128  * kvm_mips_migrate_count() - Migrate timer.
1129  * @vcpu:       Virtual CPU.
1130  *
1131  * Migrate CP0_Count hrtimer to the current CPU by cancelling and restarting it
1132  * if it was running prior to being cancelled.
1133  *
1134  * Must be called when the VCPU is migrated to a different CPU to ensure that
1135  * timer expiry during guest execution interrupts the guest and causes the
1136  * interrupt to be delivered in a timely manner.
1137  */
1138 static void kvm_mips_migrate_count(struct kvm_vcpu *vcpu)
1139 {
1140         if (hrtimer_cancel(&vcpu->arch.comparecount_timer))
1141                 hrtimer_restart(&vcpu->arch.comparecount_timer);
1142 }
1143
1144 /* Restore ASID once we are scheduled back after preemption */
1145 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
1146 {
1147         unsigned long flags;
1148
1149         kvm_debug("%s: vcpu %p, cpu: %d\n", __func__, vcpu, cpu);
1150
1151         local_irq_save(flags);
1152
1153         vcpu->cpu = cpu;
1154         if (vcpu->arch.last_sched_cpu != cpu) {
1155                 kvm_debug("[%d->%d]KVM VCPU[%d] switch\n",
1156                           vcpu->arch.last_sched_cpu, cpu, vcpu->vcpu_id);
1157                 /*
1158                  * Migrate the timer interrupt to the current CPU so that it
1159                  * always interrupts the guest and synchronously triggers a
1160                  * guest timer interrupt.
1161                  */
1162                 kvm_mips_migrate_count(vcpu);
1163         }
1164
1165         /* restore guest state to registers */
1166         kvm_mips_callbacks->vcpu_load(vcpu, cpu);
1167
1168         local_irq_restore(flags);
1169 }
1170
1171 /* ASID can change if another task is scheduled during preemption */
1172 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
1173 {
1174         unsigned long flags;
1175         int cpu;
1176
1177         local_irq_save(flags);
1178
1179         cpu = smp_processor_id();
1180         vcpu->arch.last_sched_cpu = cpu;
1181         vcpu->cpu = -1;
1182
1183         /* save guest state in registers */
1184         kvm_mips_callbacks->vcpu_put(vcpu, cpu);
1185
1186         local_irq_restore(flags);
1187 }
1188
1189 /**
1190  * kvm_trap_emul_gva_fault() - Safely attempt to handle a GVA access fault.
1191  * @vcpu:       Virtual CPU.
1192  * @gva:        Guest virtual address to be accessed.
1193  * @write:      True if write attempted (must be dirtied and made writable).
1194  *
1195  * Safely attempt to handle a GVA fault, mapping GVA pages if necessary, and
1196  * dirtying the page if @write so that guest instructions can be modified.
1197  *
1198  * Returns:     KVM_MIPS_MAPPED on success.
1199  *              KVM_MIPS_GVA if bad guest virtual address.
1200  *              KVM_MIPS_GPA if bad guest physical address.
1201  *              KVM_MIPS_TLB if guest TLB not present.
1202  *              KVM_MIPS_TLBINV if guest TLB present but not valid.
1203  *              KVM_MIPS_TLBMOD if guest TLB read only.
1204  */
1205 enum kvm_mips_fault_result kvm_trap_emul_gva_fault(struct kvm_vcpu *vcpu,
1206                                                    unsigned long gva,
1207                                                    bool write)
1208 {
1209         struct mips_coproc *cop0 = vcpu->arch.cop0;
1210         struct kvm_mips_tlb *tlb;
1211         int index;
1212
1213         if (KVM_GUEST_KSEGX(gva) == KVM_GUEST_KSEG0) {
1214                 if (kvm_mips_handle_kseg0_tlb_fault(gva, vcpu, write) < 0)
1215                         return KVM_MIPS_GPA;
1216         } else if ((KVM_GUEST_KSEGX(gva) < KVM_GUEST_KSEG0) ||
1217                    KVM_GUEST_KSEGX(gva) == KVM_GUEST_KSEG23) {
1218                 /* Address should be in the guest TLB */
1219                 index = kvm_mips_guest_tlb_lookup(vcpu, (gva & VPN2_MASK) |
1220                           (kvm_read_c0_guest_entryhi(cop0) & KVM_ENTRYHI_ASID));
1221                 if (index < 0)
1222                         return KVM_MIPS_TLB;
1223                 tlb = &vcpu->arch.guest_tlb[index];
1224
1225                 /* Entry should be valid, and dirty for writes */
1226                 if (!TLB_IS_VALID(*tlb, gva))
1227                         return KVM_MIPS_TLBINV;
1228                 if (write && !TLB_IS_DIRTY(*tlb, gva))
1229                         return KVM_MIPS_TLBMOD;
1230
1231                 if (kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb, gva, write))
1232                         return KVM_MIPS_GPA;
1233         } else {
1234                 return KVM_MIPS_GVA;
1235         }
1236
1237         return KVM_MIPS_MAPPED;
1238 }
1239
1240 int kvm_get_inst(u32 *opc, struct kvm_vcpu *vcpu, u32 *out)
1241 {
1242         int err;
1243
1244         if (WARN(IS_ENABLED(CONFIG_KVM_MIPS_VZ),
1245                  "Expect BadInstr/BadInstrP registers to be used with VZ\n"))
1246                 return -EINVAL;
1247
1248 retry:
1249         kvm_trap_emul_gva_lockless_begin(vcpu);
1250         err = get_user(*out, opc);
1251         kvm_trap_emul_gva_lockless_end(vcpu);
1252
1253         if (unlikely(err)) {
1254                 /*
1255                  * Try to handle the fault, maybe we just raced with a GVA
1256                  * invalidation.
1257                  */
1258                 err = kvm_trap_emul_gva_fault(vcpu, (unsigned long)opc,
1259                                               false);
1260                 if (unlikely(err)) {
1261                         kvm_err("%s: illegal address: %p\n",
1262                                 __func__, opc);
1263                         return -EFAULT;
1264                 }
1265
1266                 /* Hopefully it'll work now */
1267                 goto retry;
1268         }
1269         return 0;
1270 }