drivers/kvm/mmu.c

   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 #include <linux/types.h>
  20 #include <linux/string.h>
  21 #include <asm/page.h>
  22 #include <linux/mm.h>
  23 #include <linux/highmem.h>
  24 #include <linux/module.h>
  25
  26 #include "vmx.h"
  27 #include "kvm.h"
  28
  29 #define pgprintk(x...) do { printk(x); } while (0)
  30 #define rmap_printk(x...) do { printk(x); } while (0)
  31
  32 #define ASSERT(x)                                                       \
  33         if (!(x)) {                                                     \
  34                 printk(KERN_WARNING "assertion failed %s:%d: %s\n",     \
  35                        __FILE__, __LINE__, #x);                         \
  36         }
  37
  38 #define PT64_PT_BITS 9
  39 #define PT64_ENT_PER_PAGE (1 << PT64_PT_BITS)
  40 #define PT32_PT_BITS 10
  41 #define PT32_ENT_PER_PAGE (1 << PT32_PT_BITS)
  42
  43 #define PT_WRITABLE_SHIFT 1
  44
  45 #define PT_PRESENT_MASK (1ULL << 0)
  46 #define PT_WRITABLE_MASK (1ULL << PT_WRITABLE_SHIFT)
  47 #define PT_USER_MASK (1ULL << 2)
  48 #define PT_PWT_MASK (1ULL << 3)
  49 #define PT_PCD_MASK (1ULL << 4)
  50 #define PT_ACCESSED_MASK (1ULL << 5)
  51 #define PT_DIRTY_MASK (1ULL << 6)
  52 #define PT_PAGE_SIZE_MASK (1ULL << 7)
  53 #define PT_PAT_MASK (1ULL << 7)
  54 #define PT_GLOBAL_MASK (1ULL << 8)
  55 #define PT64_NX_MASK (1ULL << 63)
  56
  57 #define PT_PAT_SHIFT 7
  58 #define PT_DIR_PAT_SHIFT 12
  59 #define PT_DIR_PAT_MASK (1ULL << PT_DIR_PAT_SHIFT)
  60
  61 #define PT32_DIR_PSE36_SIZE 4
  62 #define PT32_DIR_PSE36_SHIFT 13
  63 #define PT32_DIR_PSE36_MASK (((1ULL << PT32_DIR_PSE36_SIZE) - 1) << PT32_DIR_PSE36_SHIFT)
  64
  65
  66 #define PT32_PTE_COPY_MASK \
  67         (PT_PRESENT_MASK | PT_ACCESSED_MASK | PT_DIRTY_MASK | PT_GLOBAL_MASK)
  68
  69 #define PT64_PTE_COPY_MASK (PT64_NX_MASK | PT32_PTE_COPY_MASK)
  70
  71 #define PT_FIRST_AVAIL_BITS_SHIFT 9
  72 #define PT64_SECOND_AVAIL_BITS_SHIFT 52
  73
  74 #define PT_SHADOW_PS_MARK (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
  75 #define PT_SHADOW_IO_MARK (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
  76
  77 #define PT_SHADOW_WRITABLE_SHIFT (PT_FIRST_AVAIL_BITS_SHIFT + 1)
  78 #define PT_SHADOW_WRITABLE_MASK (1ULL << PT_SHADOW_WRITABLE_SHIFT)
  79
  80 #define PT_SHADOW_USER_SHIFT (PT_SHADOW_WRITABLE_SHIFT + 1)
  81 #define PT_SHADOW_USER_MASK (1ULL << (PT_SHADOW_USER_SHIFT))
  82
  83 #define PT_SHADOW_BITS_OFFSET (PT_SHADOW_WRITABLE_SHIFT - PT_WRITABLE_SHIFT)
  84
  85 #define VALID_PAGE(x) ((x) != INVALID_PAGE)
  86
  87 #define PT64_LEVEL_BITS 9
  88
  89 #define PT64_LEVEL_SHIFT(level) \
  90                 ( PAGE_SHIFT + (level - 1) * PT64_LEVEL_BITS )
  91
  92 #define PT64_LEVEL_MASK(level) \
  93                 (((1ULL << PT64_LEVEL_BITS) - 1) << PT64_LEVEL_SHIFT(level))
  94
  95 #define PT64_INDEX(address, level)\
  96         (((address) >> PT64_LEVEL_SHIFT(level)) & ((1 << PT64_LEVEL_BITS) - 1))
  97
  98
  99 #define PT32_LEVEL_BITS 10
 100
 101 #define PT32_LEVEL_SHIFT(level) \
 102                 ( PAGE_SHIFT + (level - 1) * PT32_LEVEL_BITS )
 103
 104 #define PT32_LEVEL_MASK(level) \
 105                 (((1ULL << PT32_LEVEL_BITS) - 1) << PT32_LEVEL_SHIFT(level))
 106
 107 #define PT32_INDEX(address, level)\
 108         (((address) >> PT32_LEVEL_SHIFT(level)) & ((1 << PT32_LEVEL_BITS) - 1))
 109
 110
 111 #define PT64_BASE_ADDR_MASK (((1ULL << 52) - 1) & PAGE_MASK)
 112 #define PT64_DIR_BASE_ADDR_MASK \
 113         (PT64_BASE_ADDR_MASK & ~((1ULL << (PAGE_SHIFT + PT64_LEVEL_BITS)) - 1))
 114
 115 #define PT32_BASE_ADDR_MASK PAGE_MASK
 116 #define PT32_DIR_BASE_ADDR_MASK \
 117         (PAGE_MASK & ~((1ULL << (PAGE_SHIFT + PT32_LEVEL_BITS)) - 1))
 118
 119
 120 #define PFERR_PRESENT_MASK (1U << 0)
 121 #define PFERR_WRITE_MASK (1U << 1)
 122 #define PFERR_USER_MASK (1U << 2)
 123
 124 #define PT64_ROOT_LEVEL 4
 125 #define PT32_ROOT_LEVEL 2
 126 #define PT32E_ROOT_LEVEL 3
 127
 128 #define PT_DIRECTORY_LEVEL 2
 129 #define PT_PAGE_TABLE_LEVEL 1
 130
 131 #define RMAP_EXT 4
 132
 133 struct kvm_rmap_desc {
 134         u64 *shadow_ptes[RMAP_EXT];
 135         struct kvm_rmap_desc *more;
 136 };
 137
 138 static int is_write_protection(struct kvm_vcpu *vcpu)
 139 {
 140         return vcpu->cr0 & CR0_WP_MASK;
 141 }
 142
 143 static int is_cpuid_PSE36(void)
 144 {
 145         return 1;
 146 }
 147
 148 static int is_present_pte(unsigned long pte)
 149 {
 150         return pte & PT_PRESENT_MASK;
 151 }
 152
 153 static int is_writeble_pte(unsigned long pte)
 154 {
 155         return pte & PT_WRITABLE_MASK;
 156 }
 157
 158 static int is_io_pte(unsigned long pte)
 159 {
 160         return pte & PT_SHADOW_IO_MARK;
 161 }
 162
 163 static int is_rmap_pte(u64 pte)
 164 {
 165         return (pte & (PT_WRITABLE_MASK | PT_PRESENT_MASK))
 166                 == (PT_WRITABLE_MASK | PT_PRESENT_MASK);
 167 }
 168
 169 /*
 170  * Reverse mapping data structures:
 171  *
 172  * If page->private bit zero is zero, then page->private points to the
 173  * shadow page table entry that points to page_address(page).
 174  *
 175  * If page->private bit zero is one, (then page->private & ~1) points
 176  * to a struct kvm_rmap_desc containing more mappings.
 177  */
 178 static void rmap_add(struct kvm *kvm, u64 *spte)
 179 {
 180         struct page *page;
 181         struct kvm_rmap_desc *desc;
 182         int i;
 183
 184         if (!is_rmap_pte(*spte))
 185                 return;
 186         page = pfn_to_page((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT);
 187         if (!page->private) {
 188                 rmap_printk("rmap_add: %p %llx 0->1\n", spte, *spte);
 189                 page->private = (unsigned long)spte;
 190         } else if (!(page->private & 1)) {
 191                 rmap_printk("rmap_add: %p %llx 1->many\n", spte, *spte);
 192                 desc = kzalloc(sizeof *desc, GFP_NOWAIT);
 193                 if (!desc)
 194                         BUG(); /* FIXME: return error */
 195                 desc->shadow_ptes[0] = (u64 *)page->private;
 196                 desc->shadow_ptes[1] = spte;
 197                 page->private = (unsigned long)desc | 1;
 198         } else {
 199                 rmap_printk("rmap_add: %p %llx many->many\n", spte, *spte);
 200                 desc = (struct kvm_rmap_desc *)(page->private & ~1ul);
 201                 while (desc->shadow_ptes[RMAP_EXT-1] && desc->more)
 202                         desc = desc->more;
 203                 if (desc->shadow_ptes[RMAP_EXT-1]) {
 204                         desc->more = kzalloc(sizeof *desc->more, GFP_NOWAIT);
 205                         if (!desc->more)
 206                                 BUG(); /* FIXME: return error */
 207                         desc = desc->more;
 208                 }
 209                 for (i = 0; desc->shadow_ptes[i]; ++i)
 210                         ;
 211                 desc->shadow_ptes[i] = spte;
 212         }
 213 }
 214
 215 static void rmap_desc_remove_entry(struct page *page,
 216                                    struct kvm_rmap_desc *desc,
 217                                    int i,
 218                                    struct kvm_rmap_desc *prev_desc)
 219 {
 220         int j;
 221
 222         for (j = RMAP_EXT - 1; !desc->shadow_ptes[j] && j > i; --j)
 223                 ;
 224         desc->shadow_ptes[i] = desc->shadow_ptes[j];
 225         desc->shadow_ptes[j] = 0;
 226         if (j != 0)
 227                 return;
 228         if (!prev_desc && !desc->more)
 229                 page->private = (unsigned long)desc->shadow_ptes[0];
 230         else
 231                 if (prev_desc)
 232                         prev_desc->more = desc->more;
 233                 else
 234                         page->private = (unsigned long)desc->more | 1;
 235         kfree(desc);
 236 }
 237
 238 static void rmap_remove(struct kvm *kvm, u64 *spte)
 239 {
 240         struct page *page;
 241         struct kvm_rmap_desc *desc;
 242         struct kvm_rmap_desc *prev_desc;
 243         int i;
 244
 245         if (!is_rmap_pte(*spte))
 246                 return;
 247         page = pfn_to_page((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT);
 248         if (!page->private) {
 249                 printk(KERN_ERR "rmap_remove: %p %llx 0->BUG\n", spte, *spte);
 250                 BUG();
 251         } else if (!(page->private & 1)) {
 252                 rmap_printk("rmap_remove:  %p %llx 1->0\n", spte, *spte);
 253                 if ((u64 *)page->private != spte) {
 254                         printk(KERN_ERR "rmap_remove:  %p %llx 1->BUG\n",
 255                                spte, *spte);
 256                         BUG();
 257                 }
 258                 page->private = 0;
 259         } else {
 260                 rmap_printk("rmap_remove:  %p %llx many->many\n", spte, *spte);
 261                 desc = (struct kvm_rmap_desc *)(page->private & ~1ul);
 262                 prev_desc = NULL;
 263                 while (desc) {
 264                         for (i = 0; i < RMAP_EXT && desc->shadow_ptes[i]; ++i)
 265                                 if (desc->shadow_ptes[i] == spte) {
 266                                         rmap_desc_remove_entry(page, desc, i,
 267                                                                prev_desc);
 268                                         return;
 269                                 }
 270                         prev_desc = desc;
 271                         desc = desc->more;
 272                 }
 273                 BUG();
 274         }
 275 }
 276
 277 static void rmap_write_protect(struct kvm *kvm, u64 gfn)
 278 {
 279         struct page *page;
 280         struct kvm_memory_slot *slot;
 281         struct kvm_rmap_desc *desc;
 282         u64 *spte;
 283
 284         slot = gfn_to_memslot(kvm, gfn);
 285         BUG_ON(!slot);
 286         page = gfn_to_page(slot, gfn);
 287
 288         while (page->private) {
 289                 if (!(page->private & 1))
 290                         spte = (u64 *)page->private;
 291                 else {
 292                         desc = (struct kvm_rmap_desc *)(page->private & ~1ul);
 293                         spte = desc->shadow_ptes[0];
 294                 }
 295                 BUG_ON(!spte);
 296                 BUG_ON((*spte & PT64_BASE_ADDR_MASK) !=
 297                        page_to_pfn(page) << PAGE_SHIFT);
 298                 BUG_ON(!(*spte & PT_PRESENT_MASK));
 299                 BUG_ON(!(*spte & PT_WRITABLE_MASK));
 300                 rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);
 301                 rmap_remove(kvm, spte);
 302                 *spte &= ~(u64)PT_WRITABLE_MASK;
 303         }
 304 }
 305
 306 static void kvm_mmu_free_page(struct kvm_vcpu *vcpu, hpa_t page_hpa)
 307 {
 308         struct kvm_mmu_page *page_head = page_header(page_hpa);
 309
 310         list_del(&page_head->link);
 311         page_head->page_hpa = page_hpa;
 312         list_add(&page_head->link, &vcpu->free_pages);
 313         ++vcpu->kvm->n_free_mmu_pages;
 314 }
 315
 316 static int is_empty_shadow_page(hpa_t page_hpa)
 317 {
 318         u32 *pos;
 319         u32 *end;
 320         for (pos = __va(page_hpa), end = pos + PAGE_SIZE / sizeof(u32);
 321                       pos != end; pos++)
 322                 if (*pos != 0)
 323                         return 0;
 324         return 1;
 325 }
 326
 327 static unsigned kvm_page_table_hashfn(gfn_t gfn)
 328 {
 329         return gfn;
 330 }
 331
 332 static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu,
 333                                                u64 *parent_pte)
 334 {
 335         struct kvm_mmu_page *page;
 336
 337         if (list_empty(&vcpu->free_pages))
 338                 return NULL;
 339
 340         page = list_entry(vcpu->free_pages.next, struct kvm_mmu_page, link);
 341         list_del(&page->link);
 342         list_add(&page->link, &vcpu->kvm->active_mmu_pages);
 343         ASSERT(is_empty_shadow_page(page->page_hpa));
 344         page->slot_bitmap = 0;
 345         page->global = 1;
 346         page->multimapped = 0;
 347         page->parent_pte = parent_pte;
 348         --vcpu->kvm->n_free_mmu_pages;
 349         return page;
 350 }
 351
 352 static void mmu_page_add_parent_pte(struct kvm_mmu_page *page, u64 *parent_pte)
 353 {
 354         struct kvm_pte_chain *pte_chain;
 355         struct hlist_node *node;
 356         int i;
 357
 358         if (!parent_pte)
 359                 return;
 360         if (!page->multimapped) {
 361                 u64 *old = page->parent_pte;
 362
 363                 if (!old) {
 364                         page->parent_pte = parent_pte;
 365                         return;
 366                 }
 367                 page->multimapped = 1;
 368                 pte_chain = kzalloc(sizeof(struct kvm_pte_chain), GFP_NOWAIT);
 369                 BUG_ON(!pte_chain);
 370                 INIT_HLIST_HEAD(&page->parent_ptes);
 371                 hlist_add_head(&pte_chain->link, &page->parent_ptes);
 372                 pte_chain->parent_ptes[0] = old;
 373         }
 374         hlist_for_each_entry(pte_chain, node, &page->parent_ptes, link) {
 375                 if (pte_chain->parent_ptes[NR_PTE_CHAIN_ENTRIES-1])
 376                         continue;
 377                 for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i)
 378                         if (!pte_chain->parent_ptes[i]) {
 379                                 pte_chain->parent_ptes[i] = parent_pte;
 380                                 return;
 381                         }
 382         }
 383         pte_chain = kzalloc(sizeof(struct kvm_pte_chain), GFP_NOWAIT);
 384         BUG_ON(!pte_chain);
 385         hlist_add_head(&pte_chain->link, &page->parent_ptes);
 386         pte_chain->parent_ptes[0] = parent_pte;
 387 }
 388
 389 static void mmu_page_remove_parent_pte(struct kvm_mmu_page *page,
 390                                        u64 *parent_pte)
 391 {
 392         struct kvm_pte_chain *pte_chain;
 393         struct hlist_node *node;
 394         int i;
 395
 396         if (!page->multimapped) {
 397                 BUG_ON(page->parent_pte != parent_pte);
 398                 page->parent_pte = NULL;
 399                 return;
 400         }
 401         hlist_for_each_entry(pte_chain, node, &page->parent_ptes, link)
 402                 for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i) {
 403                         if (!pte_chain->parent_ptes[i])
 404                                 break;
 405                         if (pte_chain->parent_ptes[i] != parent_pte)
 406                                 continue;
 407                         while (i + 1 < NR_PTE_CHAIN_ENTRIES
 408                                 && pte_chain->parent_ptes[i + 1]) {
 409                                 pte_chain->parent_ptes[i]
 410                                         = pte_chain->parent_ptes[i + 1];
 411                                 ++i;
 412                         }
 413                         pte_chain->parent_ptes[i] = NULL;
 414                         if (i == 0) {
 415                                 hlist_del(&pte_chain->link);
 416                                 kfree(pte_chain);
 417                                 if (hlist_empty(&page->parent_ptes)) {
 418                                         page->multimapped = 0;
 419                                         page->parent_pte = NULL;
 420                                 }
 421                         }
 422                         return;
 423                 }
 424         BUG();
 425 }
 426
 427 static struct kvm_mmu_page *kvm_mmu_lookup_page(struct kvm_vcpu *vcpu,
 428                                                 gfn_t gfn)
 429 {
 430         unsigned index;
 431         struct hlist_head *bucket;
 432         struct kvm_mmu_page *page;
 433         struct hlist_node *node;
 434
 435         pgprintk("%s: looking for gfn %lx\n", __FUNCTION__, gfn);
 436         index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
 437         bucket = &vcpu->kvm->mmu_page_hash[index];
 438         hlist_for_each_entry(page, node, bucket, hash_link)
 439                 if (page->gfn == gfn && !page->role.metaphysical) {
 440                         pgprintk("%s: found role %x\n",
 441                                  __FUNCTION__, page->role.word);
 442                         return page;
 443                 }
 444         return NULL;
 445 }
 446
 447 static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
 448                                              gfn_t gfn,
 449                                              gva_t gaddr,
 450                                              unsigned level,
 451                                              int metaphysical,
 452                                              u64 *parent_pte)
 453 {
 454         union kvm_mmu_page_role role;
 455         unsigned index;
 456         unsigned quadrant;
 457         struct hlist_head *bucket;
 458         struct kvm_mmu_page *page;
 459         struct hlist_node *node;
 460
 461         role.word = 0;
 462         role.glevels = vcpu->mmu.root_level;
 463         role.level = level;
 464         role.metaphysical = metaphysical;
 465         if (vcpu->mmu.root_level <= PT32_ROOT_LEVEL) {
 466                 quadrant = gaddr >> (PAGE_SHIFT + (PT64_PT_BITS * level));
 467                 quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;
 468                 role.quadrant = quadrant;
 469         }
 470         pgprintk("%s: looking gfn %lx role %x\n", __FUNCTION__,
 471                  gfn, role.word);
 472         index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
 473         bucket = &vcpu->kvm->mmu_page_hash[index];
 474         hlist_for_each_entry(page, node, bucket, hash_link)
 475                 if (page->gfn == gfn && page->role.word == role.word) {
 476                         mmu_page_add_parent_pte(page, parent_pte);
 477                         pgprintk("%s: found\n", __FUNCTION__);
 478                         return page;
 479                 }
 480         page = kvm_mmu_alloc_page(vcpu, parent_pte);
 481         if (!page)
 482                 return page;
 483         pgprintk("%s: adding gfn %lx role %x\n", __FUNCTION__, gfn, role.word);
 484         page->gfn = gfn;
 485         page->role = role;
 486         hlist_add_head(&page->hash_link, bucket);
 487         if (!metaphysical)
 488                 rmap_write_protect(vcpu->kvm, gfn);
 489         return page;
 490 }
 491
 492 static void kvm_mmu_page_unlink_children(struct kvm_vcpu *vcpu,
 493                                          struct kvm_mmu_page *page)
 494 {
 495         unsigned i;
 496         u64 *pt;
 497         u64 ent;
 498
 499         pt = __va(page->page_hpa);
 500
 501         if (page->role.level == PT_PAGE_TABLE_LEVEL) {
 502                 for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
 503                         if (pt[i] & PT_PRESENT_MASK)
 504                                 rmap_remove(vcpu->kvm, &pt[i]);
 505                         pt[i] = 0;
 506                 }
 507                 return;
 508         }
 509
 510         for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
 511                 ent = pt[i];
 512
 513                 pt[i] = 0;
 514                 if (!(ent & PT_PRESENT_MASK))
 515                         continue;
 516                 ent &= PT64_BASE_ADDR_MASK;
 517                 mmu_page_remove_parent_pte(page_header(ent), &pt[i]);
 518         }
 519 }
 520
 521 static void kvm_mmu_put_page(struct kvm_vcpu *vcpu,
 522                              struct kvm_mmu_page *page,
 523                              u64 *parent_pte)
 524 {
 525         mmu_page_remove_parent_pte(page, parent_pte);
 526 }
 527
 528 static void kvm_mmu_zap_page(struct kvm_vcpu *vcpu,
 529                              struct kvm_mmu_page *page)
 530 {
 531         u64 *parent_pte;
 532
 533         while (page->multimapped || page->parent_pte) {
 534                 if (!page->multimapped)
 535                         parent_pte = page->parent_pte;
 536                 else {
 537                         struct kvm_pte_chain *chain;
 538
 539                         chain = container_of(page->parent_ptes.first,
 540                                              struct kvm_pte_chain, link);
 541                         parent_pte = chain->parent_ptes[0];
 542                 }
 543                 BUG_ON(!parent_pte);
 544                 kvm_mmu_put_page(vcpu, page, parent_pte);
 545                 *parent_pte = 0;
 546         }
 547         kvm_mmu_page_unlink_children(vcpu, page);
 548         hlist_del(&page->hash_link);
 549         kvm_mmu_free_page(vcpu, page->page_hpa);
 550 }
 551
 552 static int kvm_mmu_unprotect_page(struct kvm_vcpu *vcpu, gfn_t gfn)
 553 {
 554         unsigned index;
 555         struct hlist_head *bucket;
 556         struct kvm_mmu_page *page;
 557         struct hlist_node *node, *n;
 558         int r;
 559
 560         pgprintk("%s: looking for gfn %lx\n", __FUNCTION__, gfn);
 561         r = 0;
 562         index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
 563         bucket = &vcpu->kvm->mmu_page_hash[index];
 564         hlist_for_each_entry_safe(page, node, n, bucket, hash_link)
 565                 if (page->gfn == gfn && !page->role.metaphysical) {
 566                         pgprintk("%s: gfn %lx role %x\n", __FUNCTION__, gfn,
 567                                  page->role.word);
 568                         kvm_mmu_zap_page(vcpu, page);
 569                         r = 1;
 570                 }
 571         return r;
 572 }
 573
 574 static void page_header_update_slot(struct kvm *kvm, void *pte, gpa_t gpa)
 575 {
 576         int slot = memslot_id(kvm, gfn_to_memslot(kvm, gpa >> PAGE_SHIFT));
 577         struct kvm_mmu_page *page_head = page_header(__pa(pte));
 578
 579         __set_bit(slot, &page_head->slot_bitmap);
 580 }
 581
 582 hpa_t safe_gpa_to_hpa(struct kvm_vcpu *vcpu, gpa_t gpa)
 583 {
 584         hpa_t hpa = gpa_to_hpa(vcpu, gpa);
 585
 586         return is_error_hpa(hpa) ? bad_page_address | (gpa & ~PAGE_MASK): hpa;
 587 }
 588
 589 hpa_t gpa_to_hpa(struct kvm_vcpu *vcpu, gpa_t gpa)
 590 {
 591         struct kvm_memory_slot *slot;
 592         struct page *page;
 593
 594         ASSERT((gpa & HPA_ERR_MASK) == 0);
 595         slot = gfn_to_memslot(vcpu->kvm, gpa >> PAGE_SHIFT);
 596         if (!slot)
 597                 return gpa | HPA_ERR_MASK;
 598         page = gfn_to_page(slot, gpa >> PAGE_SHIFT);
 599         return ((hpa_t)page_to_pfn(page) << PAGE_SHIFT)
 600                 | (gpa & (PAGE_SIZE-1));
 601 }
 602
 603 hpa_t gva_to_hpa(struct kvm_vcpu *vcpu, gva_t gva)
 604 {
 605         gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, gva);
 606
 607         if (gpa == UNMAPPED_GVA)
 608                 return UNMAPPED_GVA;
 609         return gpa_to_hpa(vcpu, gpa);
 610 }
 611
 612
 613 static void release_pt_page_64(struct kvm_vcpu *vcpu, hpa_t page_hpa,
 614                                int level)
 615 {
 616         u64 *pos;
 617         u64 *end;
 618
 619         ASSERT(vcpu);
 620         ASSERT(VALID_PAGE(page_hpa));
 621         ASSERT(level <= PT64_ROOT_LEVEL && level > 0);
 622
 623         for (pos = __va(page_hpa), end = pos + PT64_ENT_PER_PAGE;
 624              pos != end; pos++) {
 625                 u64 current_ent = *pos;
 626
 627                 if (is_present_pte(current_ent)) {
 628                         if (level != 1)
 629                                 release_pt_page_64(vcpu,
 630                                                   current_ent &
 631                                                   PT64_BASE_ADDR_MASK,
 632                                                   level - 1);
 633                         else
 634                                 rmap_remove(vcpu->kvm, pos);
 635                 }
 636                 *pos = 0;
 637         }
 638         kvm_mmu_free_page(vcpu, page_hpa);
 639 }
 640
 641 static void nonpaging_new_cr3(struct kvm_vcpu *vcpu)
 642 {
 643 }
 644
 645 static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, hpa_t p)
 646 {
 647         int level = PT32E_ROOT_LEVEL;
 648         hpa_t table_addr = vcpu->mmu.root_hpa;
 649
 650         for (; ; level--) {
 651                 u32 index = PT64_INDEX(v, level);
 652                 u64 *table;
 653                 u64 pte;
 654
 655                 ASSERT(VALID_PAGE(table_addr));
 656                 table = __va(table_addr);
 657
 658                 if (level == 1) {
 659                         pte = table[index];
 660                         if (is_present_pte(pte) && is_writeble_pte(pte))
 661                                 return 0;
 662                         mark_page_dirty(vcpu->kvm, v >> PAGE_SHIFT);
 663                         page_header_update_slot(vcpu->kvm, table, v);
 664                         table[index] = p | PT_PRESENT_MASK | PT_WRITABLE_MASK |
 665                                                                 PT_USER_MASK;
 666                         rmap_add(vcpu->kvm, &table[index]);
 667                         return 0;
 668                 }
 669
 670                 if (table[index] == 0) {
 671                         struct kvm_mmu_page *new_table;
 672                         gfn_t pseudo_gfn;
 673
 674                         pseudo_gfn = (v & PT64_DIR_BASE_ADDR_MASK)
 675                                 >> PAGE_SHIFT;
 676                         new_table = kvm_mmu_get_page(vcpu, pseudo_gfn,
 677                                                      v, level - 1,
 678                                                      1, &table[index]);
 679                         if (!new_table) {
 680                                 pgprintk("nonpaging_map: ENOMEM\n");
 681                                 return -ENOMEM;
 682                         }
 683
 684                         table[index] = new_table->page_hpa | PT_PRESENT_MASK
 685                                 | PT_WRITABLE_MASK | PT_USER_MASK;
 686                 }
 687                 table_addr = table[index] & PT64_BASE_ADDR_MASK;
 688         }
 689 }
 690
 691 static void mmu_free_roots(struct kvm_vcpu *vcpu)
 692 {
 693         int i;
 694
 695 #ifdef CONFIG_X86_64
 696         if (vcpu->mmu.shadow_root_level == PT64_ROOT_LEVEL) {
 697                 hpa_t root = vcpu->mmu.root_hpa;
 698
 699                 ASSERT(VALID_PAGE(root));
 700                 vcpu->mmu.root_hpa = INVALID_PAGE;
 701                 return;
 702         }
 703 #endif
 704         for (i = 0; i < 4; ++i) {
 705                 hpa_t root = vcpu->mmu.pae_root[i];
 706
 707                 ASSERT(VALID_PAGE(root));
 708                 root &= PT64_BASE_ADDR_MASK;
 709                 vcpu->mmu.pae_root[i] = INVALID_PAGE;
 710         }
 711         vcpu->mmu.root_hpa = INVALID_PAGE;
 712 }
 713
 714 static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
 715 {
 716         int i;
 717         gfn_t root_gfn;
 718         root_gfn = vcpu->cr3 >> PAGE_SHIFT;
 719
 720 #ifdef CONFIG_X86_64
 721         if (vcpu->mmu.shadow_root_level == PT64_ROOT_LEVEL) {
 722                 hpa_t root = vcpu->mmu.root_hpa;
 723
 724                 ASSERT(!VALID_PAGE(root));
 725                 root = kvm_mmu_get_page(vcpu, root_gfn, 0,
 726                                         PT64_ROOT_LEVEL, 0, NULL)->page_hpa;
 727                 vcpu->mmu.root_hpa = root;
 728                 return;
 729         }
 730 #endif
 731         for (i = 0; i < 4; ++i) {
 732                 hpa_t root = vcpu->mmu.pae_root[i];
 733
 734                 ASSERT(!VALID_PAGE(root));
 735                 if (vcpu->mmu.root_level == PT32E_ROOT_LEVEL)
 736                         root_gfn = vcpu->pdptrs[i] >> PAGE_SHIFT;
 737                 else if (vcpu->mmu.root_level == 0)
 738                         root_gfn = 0;
 739                 root = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
 740                                         PT32_ROOT_LEVEL, !is_paging(vcpu),
 741                                         NULL)->page_hpa;
 742                 vcpu->mmu.pae_root[i] = root | PT_PRESENT_MASK;
 743         }
 744         vcpu->mmu.root_hpa = __pa(vcpu->mmu.pae_root);
 745 }
 746
 747 static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gva_t vaddr)
 748 {
 749         return vaddr;
 750 }
 751
 752 static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
 753                                u32 error_code)
 754 {
 755         gpa_t addr = gva;
 756         hpa_t paddr;
 757
 758         ASSERT(vcpu);
 759         ASSERT(VALID_PAGE(vcpu->mmu.root_hpa));
 760
 761
 762         paddr = gpa_to_hpa(vcpu , addr & PT64_BASE_ADDR_MASK);
 763
 764         if (is_error_hpa(paddr))
 765                 return 1;
 766
 767         return nonpaging_map(vcpu, addr & PAGE_MASK, paddr);
 768 }
 769
 770 static void nonpaging_free(struct kvm_vcpu *vcpu)
 771 {
 772         mmu_free_roots(vcpu);
 773 }
 774
 775 static int nonpaging_init_context(struct kvm_vcpu *vcpu)
 776 {
 777         struct kvm_mmu *context = &vcpu->mmu;
 778
 779         context->new_cr3 = nonpaging_new_cr3;
 780         context->page_fault = nonpaging_page_fault;
 781         context->gva_to_gpa = nonpaging_gva_to_gpa;
 782         context->free = nonpaging_free;
 783         context->root_level = 0;
 784         context->shadow_root_level = PT32E_ROOT_LEVEL;
 785         mmu_alloc_roots(vcpu);
 786         ASSERT(VALID_PAGE(context->root_hpa));
 787         kvm_arch_ops->set_cr3(vcpu, context->root_hpa);
 788         return 0;
 789 }
 790
 791 static void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu)
 792 {
 793         ++kvm_stat.tlb_flush;
 794         kvm_arch_ops->tlb_flush(vcpu);
 795 }
 796
 797 static void paging_new_cr3(struct kvm_vcpu *vcpu)
 798 {
 799         pgprintk("%s: cr3 %lx\n", __FUNCTION__, vcpu->cr3);
 800         mmu_free_roots(vcpu);
 801         mmu_alloc_roots(vcpu);
 802         kvm_mmu_flush_tlb(vcpu);
 803         kvm_arch_ops->set_cr3(vcpu, vcpu->mmu.root_hpa);
 804 }
 805
 806 static void mark_pagetable_nonglobal(void *shadow_pte)
 807 {
 808         page_header(__pa(shadow_pte))->global = 0;
 809 }
 810
 811 static inline void set_pte_common(struct kvm_vcpu *vcpu,
 812                              u64 *shadow_pte,
 813                              gpa_t gaddr,
 814                              int dirty,
 815                              u64 access_bits,
 816                              gfn_t gfn)
 817 {
 818         hpa_t paddr;
 819
 820         *shadow_pte |= access_bits << PT_SHADOW_BITS_OFFSET;
 821         if (!dirty)
 822                 access_bits &= ~PT_WRITABLE_MASK;
 823
 824         paddr = gpa_to_hpa(vcpu, gaddr & PT64_BASE_ADDR_MASK);
 825
 826         *shadow_pte |= access_bits;
 827
 828         if (!(*shadow_pte & PT_GLOBAL_MASK))
 829                 mark_pagetable_nonglobal(shadow_pte);
 830
 831         if (is_error_hpa(paddr)) {
 832                 *shadow_pte |= gaddr;
 833                 *shadow_pte |= PT_SHADOW_IO_MARK;
 834                 *shadow_pte &= ~PT_PRESENT_MASK;
 835                 return;
 836         }
 837
 838         *shadow_pte |= paddr;
 839
 840         if (access_bits & PT_WRITABLE_MASK) {
 841                 struct kvm_mmu_page *shadow;
 842
 843                 shadow = kvm_mmu_lookup_page(vcpu, gfn);
 844                 if (shadow) {
 845                         pgprintk("%s: found shadow page for %lx, marking ro\n",
 846                                  __FUNCTION__, gfn);
 847                         access_bits &= ~PT_WRITABLE_MASK;
 848                         *shadow_pte &= ~PT_WRITABLE_MASK;
 849                 }
 850         }
 851
 852         if (access_bits & PT_WRITABLE_MASK)
 853                 mark_page_dirty(vcpu->kvm, gaddr >> PAGE_SHIFT);
 854
 855         page_header_update_slot(vcpu->kvm, shadow_pte, gaddr);
 856         rmap_add(vcpu->kvm, shadow_pte);
 857 }
 858
 859 static void inject_page_fault(struct kvm_vcpu *vcpu,
 860                               u64 addr,
 861                               u32 err_code)
 862 {
 863         kvm_arch_ops->inject_page_fault(vcpu, addr, err_code);
 864 }
 865
 866 static inline int fix_read_pf(u64 *shadow_ent)
 867 {
 868         if ((*shadow_ent & PT_SHADOW_USER_MASK) &&
 869             !(*shadow_ent & PT_USER_MASK)) {
 870                 /*
 871                  * If supervisor write protect is disabled, we shadow kernel
 872                  * pages as user pages so we can trap the write access.
 873                  */
 874                 *shadow_ent |= PT_USER_MASK;
 875                 *shadow_ent &= ~PT_WRITABLE_MASK;
 876
 877                 return 1;
 878
 879         }
 880         return 0;
 881 }
 882
 883 static int may_access(u64 pte, int write, int user)
 884 {
 885
 886         if (user && !(pte & PT_USER_MASK))
 887                 return 0;
 888         if (write && !(pte & PT_WRITABLE_MASK))
 889                 return 0;
 890         return 1;
 891 }
 892
 893 static void paging_free(struct kvm_vcpu *vcpu)
 894 {
 895         nonpaging_free(vcpu);
 896 }
 897
 898 #define PTTYPE 64
 899 #include "paging_tmpl.h"
 900 #undef PTTYPE
 901
 902 #define PTTYPE 32
 903 #include "paging_tmpl.h"
 904 #undef PTTYPE
 905
 906 static int paging64_init_context_common(struct kvm_vcpu *vcpu, int level)
 907 {
 908         struct kvm_mmu *context = &vcpu->mmu;
 909
 910         ASSERT(is_pae(vcpu));
 911         context->new_cr3 = paging_new_cr3;
 912         context->page_fault = paging64_page_fault;
 913         context->gva_to_gpa = paging64_gva_to_gpa;
 914         context->free = paging_free;
 915         context->root_level = level;
 916         context->shadow_root_level = level;
 917         mmu_alloc_roots(vcpu);
 918         ASSERT(VALID_PAGE(context->root_hpa));
 919         kvm_arch_ops->set_cr3(vcpu, context->root_hpa |
 920                     (vcpu->cr3 & (CR3_PCD_MASK | CR3_WPT_MASK)));
 921         return 0;
 922 }
 923
 924 static int paging64_init_context(struct kvm_vcpu *vcpu)
 925 {
 926         return paging64_init_context_common(vcpu, PT64_ROOT_LEVEL);
 927 }
 928
 929 static int paging32_init_context(struct kvm_vcpu *vcpu)
 930 {
 931         struct kvm_mmu *context = &vcpu->mmu;
 932
 933         context->new_cr3 = paging_new_cr3;
 934         context->page_fault = paging32_page_fault;
 935         context->gva_to_gpa = paging32_gva_to_gpa;
 936         context->free = paging_free;
 937         context->root_level = PT32_ROOT_LEVEL;
 938         context->shadow_root_level = PT32E_ROOT_LEVEL;
 939         mmu_alloc_roots(vcpu);
 940         ASSERT(VALID_PAGE(context->root_hpa));
 941         kvm_arch_ops->set_cr3(vcpu, context->root_hpa |
 942                     (vcpu->cr3 & (CR3_PCD_MASK | CR3_WPT_MASK)));
 943         return 0;
 944 }
 945
 946 static int paging32E_init_context(struct kvm_vcpu *vcpu)
 947 {
 948         return paging64_init_context_common(vcpu, PT32E_ROOT_LEVEL);
 949 }
 950
 951 static int init_kvm_mmu(struct kvm_vcpu *vcpu)
 952 {
 953         ASSERT(vcpu);
 954         ASSERT(!VALID_PAGE(vcpu->mmu.root_hpa));
 955
 956         if (!is_paging(vcpu))
 957                 return nonpaging_init_context(vcpu);
 958         else if (is_long_mode(vcpu))
 959                 return paging64_init_context(vcpu);
 960         else if (is_pae(vcpu))
 961                 return paging32E_init_context(vcpu);
 962         else
 963                 return paging32_init_context(vcpu);
 964 }
 965
 966 static void destroy_kvm_mmu(struct kvm_vcpu *vcpu)
 967 {
 968         ASSERT(vcpu);
 969         if (VALID_PAGE(vcpu->mmu.root_hpa)) {
 970                 vcpu->mmu.free(vcpu);
 971                 vcpu->mmu.root_hpa = INVALID_PAGE;
 972         }
 973 }
 974
 975 int kvm_mmu_reset_context(struct kvm_vcpu *vcpu)
 976 {
 977         destroy_kvm_mmu(vcpu);
 978         return init_kvm_mmu(vcpu);
 979 }
 980
 981 void kvm_mmu_pre_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes)
 982 {
 983         gfn_t gfn = gpa >> PAGE_SHIFT;
 984         struct kvm_mmu_page *page;
 985         struct kvm_mmu_page *child;
 986         struct hlist_node *node;
 987         struct hlist_head *bucket;
 988         unsigned index;
 989         u64 *spte;
 990         u64 pte;
 991         unsigned offset = offset_in_page(gpa);
 992         unsigned page_offset;
 993         int level;
 994
 995         pgprintk("%s: gpa %llx bytes %d\n", __FUNCTION__, gpa, bytes);
 996         index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
 997         bucket = &vcpu->kvm->mmu_page_hash[index];
 998         hlist_for_each_entry(page, node, bucket, hash_link) {
 999                 if (page->gfn != gfn || page->role.metaphysical)
1000                         continue;
1001                 page_offset = offset;
1002                 level = page->role.level;
1003                 if (page->role.glevels == PT32_ROOT_LEVEL) {
1004                         page_offset <<= 1;          /* 32->64 */
1005                         page_offset &= ~PAGE_MASK;
1006                 }
1007                 spte = __va(page->page_hpa);
1008                 spte += page_offset / sizeof(*spte);
1009                 pte = *spte;
1010                 if (is_present_pte(pte)) {
1011                         if (level == PT_PAGE_TABLE_LEVEL)
1012                                 rmap_remove(vcpu->kvm, spte);
1013                         else {
1014                                 child = page_header(pte & PT64_BASE_ADDR_MASK);
1015                                 mmu_page_remove_parent_pte(child, spte);
1016                         }
1017                 }
1018                 *spte = 0;
1019         }
1020 }
1021
1022 void kvm_mmu_post_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes)
1023 {
1024 }
1025
1026 int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
1027 {
1028         gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, gva);
1029
1030         return kvm_mmu_unprotect_page(vcpu, gpa >> PAGE_SHIFT);
1031 }
1032
1033 void kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
1034 {
1035         while (vcpu->kvm->n_free_mmu_pages < KVM_REFILL_PAGES) {
1036                 struct kvm_mmu_page *page;
1037
1038                 page = container_of(vcpu->kvm->active_mmu_pages.prev,
1039                                     struct kvm_mmu_page, link);
1040                 kvm_mmu_zap_page(vcpu, page);
1041         }
1042 }
1043 EXPORT_SYMBOL_GPL(kvm_mmu_free_some_pages);
1044
1045 static void free_mmu_pages(struct kvm_vcpu *vcpu)
1046 {
1047         while (!list_empty(&vcpu->free_pages)) {
1048                 struct kvm_mmu_page *page;
1049
1050                 page = list_entry(vcpu->free_pages.next,
1051                                   struct kvm_mmu_page, link);
1052                 list_del(&page->link);
1053                 __free_page(pfn_to_page(page->page_hpa >> PAGE_SHIFT));
1054                 page->page_hpa = INVALID_PAGE;
1055         }
1056         free_page((unsigned long)vcpu->mmu.pae_root);
1057 }
1058
1059 static int alloc_mmu_pages(struct kvm_vcpu *vcpu)
1060 {
1061         struct page *page;
1062         int i;
1063
1064         ASSERT(vcpu);
1065
1066         for (i = 0; i < KVM_NUM_MMU_PAGES; i++) {
1067                 struct kvm_mmu_page *page_header = &vcpu->page_header_buf[i];
1068
1069                 INIT_LIST_HEAD(&page_header->link);
1070                 if ((page = alloc_page(GFP_KERNEL)) == NULL)
1071                         goto error_1;
1072                 page->private = (unsigned long)page_header;
1073                 page_header->page_hpa = (hpa_t)page_to_pfn(page) << PAGE_SHIFT;
1074                 memset(__va(page_header->page_hpa), 0, PAGE_SIZE);
1075                 list_add(&page_header->link, &vcpu->free_pages);
1076                 ++vcpu->kvm->n_free_mmu_pages;
1077         }
1078
1079         /*
1080          * When emulating 32-bit mode, cr3 is only 32 bits even on x86_64.
1081          * Therefore we need to allocate shadow page tables in the first
1082          * 4GB of memory, which happens to fit the DMA32 zone.
1083          */
1084         page = alloc_page(GFP_KERNEL | __GFP_DMA32);
1085         if (!page)
1086                 goto error_1;
1087         vcpu->mmu.pae_root = page_address(page);
1088         for (i = 0; i < 4; ++i)
1089                 vcpu->mmu.pae_root[i] = INVALID_PAGE;
1090
1091         return 0;
1092
1093 error_1:
1094         free_mmu_pages(vcpu);
1095         return -ENOMEM;
1096 }
1097
1098 int kvm_mmu_create(struct kvm_vcpu *vcpu)
1099 {
1100         ASSERT(vcpu);
1101         ASSERT(!VALID_PAGE(vcpu->mmu.root_hpa));
1102         ASSERT(list_empty(&vcpu->free_pages));
1103
1104         return alloc_mmu_pages(vcpu);
1105 }
1106
1107 int kvm_mmu_setup(struct kvm_vcpu *vcpu)
1108 {
1109         ASSERT(vcpu);
1110         ASSERT(!VALID_PAGE(vcpu->mmu.root_hpa));
1111         ASSERT(!list_empty(&vcpu->free_pages));
1112
1113         return init_kvm_mmu(vcpu);
1114 }
1115
1116 void kvm_mmu_destroy(struct kvm_vcpu *vcpu)
1117 {
1118         ASSERT(vcpu);
1119
1120         destroy_kvm_mmu(vcpu);
1121         free_mmu_pages(vcpu);
1122 }
1123
1124 void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
1125 {
1126         struct kvm_mmu_page *page;
1127
1128         list_for_each_entry(page, &kvm->active_mmu_pages, link) {
1129                 int i;
1130                 u64 *pt;
1131
1132                 if (!test_bit(slot, &page->slot_bitmap))
1133                         continue;
1134
1135                 pt = __va(page->page_hpa);
1136                 for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
1137                         /* avoid RMW */
1138                         if (pt[i] & PT_WRITABLE_MASK) {
1139                                 rmap_remove(kvm, &pt[i]);
1140                                 pt[i] &= ~PT_WRITABLE_MASK;
1141                         }
1142         }
1143 }