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