arch/x86/kvm/paging_tmpl.h

   1 /*
   2  * Kernel-based Virtual Machine driver for Linux
   3  *
   4  * This module enables machines with Intel VT-x extensions to run virtual
   5  * machines without emulation or binary translation.
   6  *
   7  * MMU support
   8  *
   9  * Copyright (C) 2006 Qumranet, Inc.
  10  * Copyright 2010 Red Hat, Inc. and/or its affilates.
  11  *
  12  * Authors:
  13  *   Yaniv Kamay  <yaniv@qumranet.com>
  14  *   Avi Kivity   <avi@qumranet.com>
  15  *
  16  * This work is licensed under the terms of the GNU GPL, version 2.  See
  17  * the COPYING file in the top-level directory.
  18  *
  19  */
  20
  21 /*
  22  * We need the mmu code to access both 32-bit and 64-bit guest ptes,
  23  * so the code in this file is compiled twice, once per pte size.
  24  */
  25
  26 #if PTTYPE == 64
  27         #define pt_element_t u64
  28         #define guest_walker guest_walker64
  29         #define FNAME(name) paging##64_##name
  30         #define PT_BASE_ADDR_MASK PT64_BASE_ADDR_MASK
  31         #define PT_LVL_ADDR_MASK(lvl) PT64_LVL_ADDR_MASK(lvl)
  32         #define PT_LVL_OFFSET_MASK(lvl) PT64_LVL_OFFSET_MASK(lvl)
  33         #define PT_INDEX(addr, level) PT64_INDEX(addr, level)
  34         #define PT_LEVEL_MASK(level) PT64_LEVEL_MASK(level)
  35         #define PT_LEVEL_BITS PT64_LEVEL_BITS
  36         #ifdef CONFIG_X86_64
  37         #define PT_MAX_FULL_LEVELS 4
  38         #define CMPXCHG cmpxchg
  39         #else
  40         #define CMPXCHG cmpxchg64
  41         #define PT_MAX_FULL_LEVELS 2
  42         #endif
  43 #elif PTTYPE == 32
  44         #define pt_element_t u32
  45         #define guest_walker guest_walker32
  46         #define FNAME(name) paging##32_##name
  47         #define PT_BASE_ADDR_MASK PT32_BASE_ADDR_MASK
  48         #define PT_LVL_ADDR_MASK(lvl) PT32_LVL_ADDR_MASK(lvl)
  49         #define PT_LVL_OFFSET_MASK(lvl) PT32_LVL_OFFSET_MASK(lvl)
  50         #define PT_INDEX(addr, level) PT32_INDEX(addr, level)
  51         #define PT_LEVEL_MASK(level) PT32_LEVEL_MASK(level)
  52         #define PT_LEVEL_BITS PT32_LEVEL_BITS
  53         #define PT_MAX_FULL_LEVELS 2
  54         #define CMPXCHG cmpxchg
  55 #else
  56         #error Invalid PTTYPE value
  57 #endif
  58
  59 #define gpte_to_gfn_lvl FNAME(gpte_to_gfn_lvl)
  60 #define gpte_to_gfn(pte) gpte_to_gfn_lvl((pte), PT_PAGE_TABLE_LEVEL)
  61
  62 /*
  63  * The guest_walker structure emulates the behavior of the hardware page
  64  * table walker.
  65  */
  66 struct guest_walker {
  67         int level;
  68         gfn_t table_gfn[PT_MAX_FULL_LEVELS];
  69         pt_element_t ptes[PT_MAX_FULL_LEVELS];
  70         gpa_t pte_gpa[PT_MAX_FULL_LEVELS];
  71         unsigned pt_access;
  72         unsigned pte_access;
  73         gfn_t gfn;
  74         u32 error_code;
  75 };
  76
  77 static gfn_t gpte_to_gfn_lvl(pt_element_t gpte, int lvl)
  78 {
  79         return (gpte & PT_LVL_ADDR_MASK(lvl)) >> PAGE_SHIFT;
  80 }
  81
  82 static bool FNAME(cmpxchg_gpte)(struct kvm *kvm,
  83                          gfn_t table_gfn, unsigned index,
  84                          pt_element_t orig_pte, pt_element_t new_pte)
  85 {
  86         pt_element_t ret;
  87         pt_element_t *table;
  88         struct page *page;
  89
  90         page = gfn_to_page(kvm, table_gfn);
  91
  92         table = kmap_atomic(page, KM_USER0);
  93         ret = CMPXCHG(&table[index], orig_pte, new_pte);
  94         kunmap_atomic(table, KM_USER0);
  95
  96         kvm_release_page_dirty(page);
  97
  98         return (ret != orig_pte);
  99 }
 100
 101 static unsigned FNAME(gpte_access)(struct kvm_vcpu *vcpu, pt_element_t gpte)
 102 {
 103         unsigned access;
 104
 105         access = (gpte & (PT_WRITABLE_MASK | PT_USER_MASK)) | ACC_EXEC_MASK;
 106 #if PTTYPE == 64
 107         if (is_nx(vcpu))
 108                 access &= ~(gpte >> PT64_NX_SHIFT);
 109 #endif
 110         return access;
 111 }
 112
 113 /*
 114  * Fetch a guest pte for a guest virtual address
 115  */
 116 static int FNAME(walk_addr)(struct guest_walker *walker,
 117                             struct kvm_vcpu *vcpu, gva_t addr,
 118                             int write_fault, int user_fault, int fetch_fault)
 119 {
 120         pt_element_t pte;
 121         gfn_t table_gfn;
 122         unsigned index, pt_access, uninitialized_var(pte_access);
 123         gpa_t pte_gpa;
 124         bool eperm, present, rsvd_fault;
 125
 126         trace_kvm_mmu_pagetable_walk(addr, write_fault, user_fault,
 127                                      fetch_fault);
 128 walk:
 129         present = true;
 130         eperm = rsvd_fault = false;
 131         walker->level = vcpu->arch.mmu.root_level;
 132         pte = vcpu->arch.cr3;
 133 #if PTTYPE == 64
 134         if (!is_long_mode(vcpu)) {
 135                 pte = kvm_pdptr_read(vcpu, (addr >> 30) & 3);
 136                 trace_kvm_mmu_paging_element(pte, walker->level);
 137                 if (!is_present_gpte(pte)) {
 138                         present = false;
 139                         goto error;
 140                 }
 141                 --walker->level;
 142         }
 143 #endif
 144         ASSERT((!is_long_mode(vcpu) && is_pae(vcpu)) ||
 145                (vcpu->arch.cr3 & CR3_NONPAE_RESERVED_BITS) == 0);
 146
 147         pt_access = ACC_ALL;
 148
 149         for (;;) {
 150                 index = PT_INDEX(addr, walker->level);
 151
 152                 table_gfn = gpte_to_gfn(pte);
 153                 pte_gpa = gfn_to_gpa(table_gfn);
 154                 pte_gpa += index * sizeof(pt_element_t);
 155                 walker->table_gfn[walker->level - 1] = table_gfn;
 156                 walker->pte_gpa[walker->level - 1] = pte_gpa;
 157
 158                 if (kvm_read_guest(vcpu->kvm, pte_gpa, &pte, sizeof(pte))) {
 159                         present = false;
 160                         break;
 161                 }
 162
 163                 trace_kvm_mmu_paging_element(pte, walker->level);
 164
 165                 if (!is_present_gpte(pte)) {
 166                         present = false;
 167                         break;
 168                 }
 169
 170                 if (is_rsvd_bits_set(vcpu, pte, walker->level)) {
 171                         rsvd_fault = true;
 172                         break;
 173                 }
 174
 175                 if (write_fault && !is_writable_pte(pte))
 176                         if (user_fault || is_write_protection(vcpu))
 177                                 eperm = true;
 178
 179                 if (user_fault && !(pte & PT_USER_MASK))
 180                         eperm = true;
 181
 182 #if PTTYPE == 64
 183                 if (fetch_fault && (pte & PT64_NX_MASK))
 184                         eperm = true;
 185 #endif
 186
 187                 if (!eperm && !rsvd_fault && !(pte & PT_ACCESSED_MASK)) {
 188                         trace_kvm_mmu_set_accessed_bit(table_gfn, index,
 189                                                        sizeof(pte));
 190                         if (FNAME(cmpxchg_gpte)(vcpu->kvm, table_gfn,
 191                             index, pte, pte|PT_ACCESSED_MASK))
 192                                 goto walk;
 193                         mark_page_dirty(vcpu->kvm, table_gfn);
 194                         pte |= PT_ACCESSED_MASK;
 195                 }
 196
 197                 pte_access = pt_access & FNAME(gpte_access)(vcpu, pte);
 198
 199                 walker->ptes[walker->level - 1] = pte;
 200
 201                 if ((walker->level == PT_PAGE_TABLE_LEVEL) ||
 202                     ((walker->level == PT_DIRECTORY_LEVEL) &&
 203                                 is_large_pte(pte) &&
 204                                 (PTTYPE == 64 || is_pse(vcpu))) ||
 205                     ((walker->level == PT_PDPE_LEVEL) &&
 206                                 is_large_pte(pte) &&
 207                                 is_long_mode(vcpu))) {
 208                         int lvl = walker->level;
 209
 210                         walker->gfn = gpte_to_gfn_lvl(pte, lvl);
 211                         walker->gfn += (addr & PT_LVL_OFFSET_MASK(lvl))
 212                                         >> PAGE_SHIFT;
 213
 214                         if (PTTYPE == 32 &&
 215                             walker->level == PT_DIRECTORY_LEVEL &&
 216                             is_cpuid_PSE36())
 217                                 walker->gfn += pse36_gfn_delta(pte);
 218
 219                         break;
 220                 }
 221
 222                 pt_access = pte_access;
 223                 --walker->level;
 224         }
 225
 226         if (!present || eperm || rsvd_fault)
 227                 goto error;
 228
 229         if (write_fault && !is_dirty_gpte(pte)) {
 230                 bool ret;
 231
 232                 trace_kvm_mmu_set_dirty_bit(table_gfn, index, sizeof(pte));
 233                 ret = FNAME(cmpxchg_gpte)(vcpu->kvm, table_gfn, index, pte,
 234                             pte|PT_DIRTY_MASK);
 235                 if (ret)
 236                         goto walk;
 237                 mark_page_dirty(vcpu->kvm, table_gfn);
 238                 pte |= PT_DIRTY_MASK;
 239                 walker->ptes[walker->level - 1] = pte;
 240         }
 241
 242         walker->pt_access = pt_access;
 243         walker->pte_access = pte_access;
 244         pgprintk("%s: pte %llx pte_access %x pt_access %x\n",
 245                  __func__, (u64)pte, pte_access, pt_access);
 246         return 1;
 247
 248 error:
 249         walker->error_code = 0;
 250         if (present)
 251                 walker->error_code |= PFERR_PRESENT_MASK;
 252         if (write_fault)
 253                 walker->error_code |= PFERR_WRITE_MASK;
 254         if (user_fault)
 255                 walker->error_code |= PFERR_USER_MASK;
 256         if (fetch_fault && is_nx(vcpu))
 257                 walker->error_code |= PFERR_FETCH_MASK;
 258         if (rsvd_fault)
 259                 walker->error_code |= PFERR_RSVD_MASK;
 260         trace_kvm_mmu_walker_error(walker->error_code);
 261         return 0;
 262 }
 263
 264 static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 265                               u64 *spte, const void *pte)
 266 {
 267         pt_element_t gpte;
 268         unsigned pte_access;
 269         pfn_t pfn;
 270         u64 new_spte;
 271
 272         gpte = *(const pt_element_t *)pte;
 273         if (~gpte & (PT_PRESENT_MASK | PT_ACCESSED_MASK)) {
 274                 if (!is_present_gpte(gpte)) {
 275                         if (sp->unsync)
 276                                 new_spte = shadow_trap_nonpresent_pte;
 277                         else
 278                                 new_spte = shadow_notrap_nonpresent_pte;
 279                         __set_spte(spte, new_spte);
 280                 }
 281                 return;
 282         }
 283         pgprintk("%s: gpte %llx spte %p\n", __func__, (u64)gpte, spte);
 284         pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte);
 285         if (gpte_to_gfn(gpte) != vcpu->arch.update_pte.gfn)
 286                 return;
 287         pfn = vcpu->arch.update_pte.pfn;
 288         if (is_error_pfn(pfn))
 289                 return;
 290         if (mmu_notifier_retry(vcpu, vcpu->arch.update_pte.mmu_seq))
 291                 return;
 292         kvm_get_pfn(pfn);
 293         /*
 294          * we call mmu_set_spte() with reset_host_protection = true beacuse that
 295          * vcpu->arch.update_pte.pfn was fetched from get_user_pages(write = 1).
 296          */
 297         mmu_set_spte(vcpu, spte, sp->role.access, pte_access, 0, 0,
 298                      is_dirty_gpte(gpte), NULL, PT_PAGE_TABLE_LEVEL,
 299                      gpte_to_gfn(gpte), pfn, true, true);
 300 }
 301
 302 static bool FNAME(gpte_changed)(struct kvm_vcpu *vcpu,
 303                                 struct guest_walker *gw, int level)
 304 {
 305         int r;
 306         pt_element_t curr_pte;
 307
 308         r = kvm_read_guest_atomic(vcpu->kvm, gw->pte_gpa[level - 1],
 309                                   &curr_pte, sizeof(curr_pte));
 310         return r || curr_pte != gw->ptes[level - 1];
 311 }
 312
 313 /*
 314  * Fetch a shadow pte for a specific level in the paging hierarchy.
 315  */
 316 static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
 317                          struct guest_walker *gw,
 318                          int user_fault, int write_fault, int hlevel,
 319                          int *ptwrite, pfn_t pfn)
 320 {
 321         unsigned access = gw->pt_access;
 322         struct kvm_mmu_page *sp;
 323         u64 *sptep = NULL;
 324         int direct;
 325         gfn_t table_gfn;
 326         int level;
 327         bool dirty = is_dirty_gpte(gw->ptes[gw->level - 1]);
 328         unsigned direct_access;
 329         struct kvm_shadow_walk_iterator iterator;
 330
 331         if (!is_present_gpte(gw->ptes[gw->level - 1]))
 332                 return NULL;
 333
 334         direct_access = gw->pt_access & gw->pte_access;
 335         if (!dirty)
 336                 direct_access &= ~ACC_WRITE_MASK;
 337
 338         for_each_shadow_entry(vcpu, addr, iterator) {
 339                 level = iterator.level;
 340                 sptep = iterator.sptep;
 341                 if (iterator.level == hlevel) {
 342                         mmu_set_spte(vcpu, sptep, access,
 343                                      gw->pte_access & access,
 344                                      user_fault, write_fault,
 345                                      dirty, ptwrite, level,
 346                                      gw->gfn, pfn, false, true);
 347                         break;
 348                 }
 349
 350                 if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)
 351                     && level == gw->level)
 352                         validate_direct_spte(vcpu, sptep, direct_access);
 353
 354                 drop_large_spte(vcpu, sptep);
 355
 356                 if (is_shadow_present_pte(*sptep))
 357                         continue;
 358
 359                 if (level <= gw->level) {
 360                         direct = 1;
 361                         access = direct_access;
 362
 363                         /*
 364                          * It is a large guest pages backed by small host pages,
 365                          * So we set @direct(@sp->role.direct)=1, and set
 366                          * @table_gfn(@sp->gfn)=the base page frame for linear
 367                          * translations.
 368                          */
 369                         table_gfn = gw->gfn & ~(KVM_PAGES_PER_HPAGE(level) - 1);
 370                         access &= gw->pte_access;
 371                 } else {
 372                         direct = 0;
 373                         table_gfn = gw->table_gfn[level - 2];
 374                 }
 375                 sp = kvm_mmu_get_page(vcpu, table_gfn, addr, level-1,
 376                                                direct, access, sptep);
 377                 if (!direct)
 378                         /*
 379                          * Verify that the gpte in the page we've just write
 380                          * protected is still there.
 381                          */
 382                         if (FNAME(gpte_changed)(vcpu, gw, level - 1)) {
 383                                 kvm_mmu_put_page(sp, sptep);
 384                                 kvm_release_pfn_clean(pfn);
 385                                 sptep = NULL;
 386                                 break;
 387                         }
 388
 389                 link_shadow_page(sptep, sp);
 390         }
 391
 392         return sptep;
 393 }
 394
 395 /*
 396  * Page fault handler.  There are several causes for a page fault:
 397  *   - there is no shadow pte for the guest pte
 398  *   - write access through a shadow pte marked read only so that we can set
 399  *     the dirty bit
 400  *   - write access to a shadow pte marked read only so we can update the page
 401  *     dirty bitmap, when userspace requests it
 402  *   - mmio access; in this case we will never install a present shadow pte
 403  *   - normal guest page fault due to the guest pte marked not present, not
 404  *     writable, or not executable
 405  *
 406  *  Returns: 1 if we need to emulate the instruction, 0 otherwise, or
 407  *           a negative value on error.
 408  */
 409 static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
 410                                u32 error_code)
 411 {
 412         int write_fault = error_code & PFERR_WRITE_MASK;
 413         int user_fault = error_code & PFERR_USER_MASK;
 414         int fetch_fault = error_code & PFERR_FETCH_MASK;
 415         struct guest_walker walker;
 416         u64 *sptep;
 417         int write_pt = 0;
 418         int r;
 419         pfn_t pfn;
 420         int level = PT_PAGE_TABLE_LEVEL;
 421         unsigned long mmu_seq;
 422
 423         pgprintk("%s: addr %lx err %x\n", __func__, addr, error_code);
 424         kvm_mmu_audit(vcpu, "pre page fault");
 425
 426         r = mmu_topup_memory_caches(vcpu);
 427         if (r)
 428                 return r;
 429
 430         /*
 431          * Look up the guest pte for the faulting address.
 432          */
 433         r = FNAME(walk_addr)(&walker, vcpu, addr, write_fault, user_fault,
 434                              fetch_fault);
 435
 436         /*
 437          * The page is not mapped by the guest.  Let the guest handle it.
 438          */
 439         if (!r) {
 440                 pgprintk("%s: guest page fault\n", __func__);
 441                 inject_page_fault(vcpu, addr, walker.error_code);
 442                 vcpu->arch.last_pt_write_count = 0; /* reset fork detector */
 443                 return 0;
 444         }
 445
 446         if (walker.level >= PT_DIRECTORY_LEVEL) {
 447                 level = min(walker.level, mapping_level(vcpu, walker.gfn));
 448                 walker.gfn = walker.gfn & ~(KVM_PAGES_PER_HPAGE(level) - 1);
 449         }
 450
 451         mmu_seq = vcpu->kvm->mmu_notifier_seq;
 452         smp_rmb();
 453         pfn = gfn_to_pfn(vcpu->kvm, walker.gfn);
 454
 455         /* mmio */
 456         if (is_error_pfn(pfn))
 457                 return kvm_handle_bad_page(vcpu->kvm, walker.gfn, pfn);
 458
 459         spin_lock(&vcpu->kvm->mmu_lock);
 460         if (mmu_notifier_retry(vcpu, mmu_seq))
 461                 goto out_unlock;
 462         kvm_mmu_free_some_pages(vcpu);
 463         sptep = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
 464                              level, &write_pt, pfn);
 465         (void)sptep;
 466         pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __func__,
 467                  sptep, *sptep, write_pt);
 468
 469         if (!write_pt)
 470                 vcpu->arch.last_pt_write_count = 0; /* reset fork detector */
 471
 472         ++vcpu->stat.pf_fixed;
 473         kvm_mmu_audit(vcpu, "post page fault (fixed)");
 474         spin_unlock(&vcpu->kvm->mmu_lock);
 475
 476         return write_pt;
 477
 478 out_unlock:
 479         spin_unlock(&vcpu->kvm->mmu_lock);
 480         kvm_release_pfn_clean(pfn);
 481         return 0;
 482 }
 483
 484 static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva)
 485 {
 486         struct kvm_shadow_walk_iterator iterator;
 487         struct kvm_mmu_page *sp;
 488         gpa_t pte_gpa = -1;
 489         int level;
 490         u64 *sptep;
 491         int need_flush = 0;
 492
 493         spin_lock(&vcpu->kvm->mmu_lock);
 494
 495         for_each_shadow_entry(vcpu, gva, iterator) {
 496                 level = iterator.level;
 497                 sptep = iterator.sptep;
 498
 499                 sp = page_header(__pa(sptep));
 500                 if (is_last_spte(*sptep, level)) {
 501                         int offset, shift;
 502
 503                         if (!sp->unsync)
 504                                 break;
 505
 506                         shift = PAGE_SHIFT -
 507                                   (PT_LEVEL_BITS - PT64_LEVEL_BITS) * level;
 508                         offset = sp->role.quadrant << shift;
 509
 510                         pte_gpa = (sp->gfn << PAGE_SHIFT) + offset;
 511                         pte_gpa += (sptep - sp->spt) * sizeof(pt_element_t);
 512
 513                         if (is_shadow_present_pte(*sptep)) {
 514                                 if (is_large_pte(*sptep))
 515                                         --vcpu->kvm->stat.lpages;
 516                                 drop_spte(vcpu->kvm, sptep,
 517                                           shadow_trap_nonpresent_pte);
 518                                 need_flush = 1;
 519                         } else
 520                                 __set_spte(sptep, shadow_trap_nonpresent_pte);
 521                         break;
 522                 }
 523
 524                 if (!is_shadow_present_pte(*sptep) || !sp->unsync_children)
 525                         break;
 526         }
 527
 528         if (need_flush)
 529                 kvm_flush_remote_tlbs(vcpu->kvm);
 530
 531         atomic_inc(&vcpu->kvm->arch.invlpg_counter);
 532
 533         spin_unlock(&vcpu->kvm->mmu_lock);
 534
 535         if (pte_gpa == -1)
 536                 return;
 537
 538         if (mmu_topup_memory_caches(vcpu))
 539                 return;
 540         kvm_mmu_pte_write(vcpu, pte_gpa, NULL, sizeof(pt_element_t), 0);
 541 }
 542
 543 static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr, u32 access,
 544                                u32 *error)
 545 {
 546         struct guest_walker walker;
 547         gpa_t gpa = UNMAPPED_GVA;
 548         int r;
 549
 550         r = FNAME(walk_addr)(&walker, vcpu, vaddr,
 551                              !!(access & PFERR_WRITE_MASK),
 552                              !!(access & PFERR_USER_MASK),
 553                              !!(access & PFERR_FETCH_MASK));
 554
 555         if (r) {
 556                 gpa = gfn_to_gpa(walker.gfn);
 557                 gpa |= vaddr & ~PAGE_MASK;
 558         } else if (error)
 559                 *error = walker.error_code;
 560
 561         return gpa;
 562 }
 563
 564 static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu,
 565                                  struct kvm_mmu_page *sp)
 566 {
 567         int i, j, offset, r;
 568         pt_element_t pt[256 / sizeof(pt_element_t)];
 569         gpa_t pte_gpa;
 570
 571         if (sp->role.direct
 572             || (PTTYPE == 32 && sp->role.level > PT_PAGE_TABLE_LEVEL)) {
 573                 nonpaging_prefetch_page(vcpu, sp);
 574                 return;
 575         }
 576
 577         pte_gpa = gfn_to_gpa(sp->gfn);
 578         if (PTTYPE == 32) {
 579                 offset = sp->role.quadrant << PT64_LEVEL_BITS;
 580                 pte_gpa += offset * sizeof(pt_element_t);
 581         }
 582
 583         for (i = 0; i < PT64_ENT_PER_PAGE; i += ARRAY_SIZE(pt)) {
 584                 r = kvm_read_guest_atomic(vcpu->kvm, pte_gpa, pt, sizeof pt);
 585                 pte_gpa += ARRAY_SIZE(pt) * sizeof(pt_element_t);
 586                 for (j = 0; j < ARRAY_SIZE(pt); ++j)
 587                         if (r || is_present_gpte(pt[j]))
 588                                 sp->spt[i+j] = shadow_trap_nonpresent_pte;
 589                         else
 590                                 sp->spt[i+j] = shadow_notrap_nonpresent_pte;
 591         }
 592 }
 593
 594 /*
 595  * Using the cached information from sp->gfns is safe because:
 596  * - The spte has a reference to the struct page, so the pfn for a given gfn
 597  *   can't change unless all sptes pointing to it are nuked first.
 598  */
 599 static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 600                             bool clear_unsync)
 601 {
 602         int i, offset, nr_present;
 603         bool reset_host_protection;
 604         gpa_t first_pte_gpa;
 605
 606         offset = nr_present = 0;
 607
 608         /* direct kvm_mmu_page can not be unsync. */
 609         BUG_ON(sp->role.direct);
 610
 611         if (PTTYPE == 32)
 612                 offset = sp->role.quadrant << PT64_LEVEL_BITS;
 613
 614         first_pte_gpa = gfn_to_gpa(sp->gfn) + offset * sizeof(pt_element_t);
 615
 616         for (i = 0; i < PT64_ENT_PER_PAGE; i++) {
 617                 unsigned pte_access;
 618                 pt_element_t gpte;
 619                 gpa_t pte_gpa;
 620                 gfn_t gfn;
 621
 622                 if (!is_shadow_present_pte(sp->spt[i]))
 623                         continue;
 624
 625                 pte_gpa = first_pte_gpa + i * sizeof(pt_element_t);
 626
 627                 if (kvm_read_guest_atomic(vcpu->kvm, pte_gpa, &gpte,
 628                                           sizeof(pt_element_t)))
 629                         return -EINVAL;
 630
 631                 gfn = gpte_to_gfn(gpte);
 632                 if (gfn != sp->gfns[i] ||
 633                       !is_present_gpte(gpte) || !(gpte & PT_ACCESSED_MASK)) {
 634                         u64 nonpresent;
 635
 636                         if (is_present_gpte(gpte) || !clear_unsync)
 637                                 nonpresent = shadow_trap_nonpresent_pte;
 638                         else
 639                                 nonpresent = shadow_notrap_nonpresent_pte;
 640                         drop_spte(vcpu->kvm, &sp->spt[i], nonpresent);
 641                         continue;
 642                 }
 643
 644                 nr_present++;
 645                 pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte);
 646                 if (!(sp->spt[i] & SPTE_HOST_WRITEABLE)) {
 647                         pte_access &= ~ACC_WRITE_MASK;
 648                         reset_host_protection = 0;
 649                 } else {
 650                         reset_host_protection = 1;
 651                 }
 652                 set_spte(vcpu, &sp->spt[i], pte_access, 0, 0,
 653                          is_dirty_gpte(gpte), PT_PAGE_TABLE_LEVEL, gfn,
 654                          spte_to_pfn(sp->spt[i]), true, false,
 655                          reset_host_protection);
 656         }
 657
 658         return !nr_present;
 659 }
 660
 661 #undef pt_element_t
 662 #undef guest_walker
 663 #undef FNAME
 664 #undef PT_BASE_ADDR_MASK
 665 #undef PT_INDEX
 666 #undef PT_LEVEL_MASK
 667 #undef PT_LVL_ADDR_MASK
 668 #undef PT_LVL_OFFSET_MASK
 669 #undef PT_LEVEL_BITS
 670 #undef PT_MAX_FULL_LEVELS
 671 #undef gpte_to_gfn
 672 #undef gpte_to_gfn_lvl
 673 #undef CMPXCHG