arch/x86/xen/p2m.c

   1 /*
   2  * Xen leaves the responsibility for maintaining p2m mappings to the
   3  * guests themselves, but it must also access and update the p2m array
   4  * during suspend/resume when all the pages are reallocated.
   5  *
   6  * The logical flat p2m table is mapped to a linear kernel memory area.
   7  * For accesses by Xen a three-level tree linked via mfns only is set up to
   8  * allow the address space to be sparse.
   9  *
  10  *               Xen
  11  *                |
  12  *          p2m_top_mfn
  13  *              /   \
  14  * p2m_mid_mfn p2m_mid_mfn
  15  *         /           /
  16  *  p2m p2m p2m ...
  17  *
  18  * The p2m_mid_mfn pages are mapped by p2m_top_mfn_p.
  19  *
  20  * The p2m_top_mfn level is limited to 1 page, so the maximum representable
  21  * pseudo-physical address space is:
  22  *  P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE pages
  23  *
  24  * P2M_PER_PAGE depends on the architecture, as a mfn is always
  25  * unsigned long (8 bytes on 64-bit, 4 bytes on 32), leading to
  26  * 512 and 1024 entries respectively.
  27  *
  28  * In short, these structures contain the Machine Frame Number (MFN) of the PFN.
  29  *
  30  * However not all entries are filled with MFNs. Specifically for all other
  31  * leaf entries, or for the top  root, or middle one, for which there is a void
  32  * entry, we assume it is  "missing". So (for example)
  33  *  pfn_to_mfn(0x90909090)=INVALID_P2M_ENTRY.
  34  * We have a dedicated page p2m_missing with all entries being
  35  * INVALID_P2M_ENTRY. This page may be referenced multiple times in the p2m
  36  * list/tree in case there are multiple areas with P2M_PER_PAGE invalid pfns.
  37  *
  38  * We also have the possibility of setting 1-1 mappings on certain regions, so
  39  * that:
  40  *  pfn_to_mfn(0xc0000)=0xc0000
  41  *
  42  * The benefit of this is, that we can assume for non-RAM regions (think
  43  * PCI BARs, or ACPI spaces), we can create mappings easily because we
  44  * get the PFN value to match the MFN.
  45  *
  46  * For this to work efficiently we have one new page p2m_identity. All entries
  47  * in p2m_identity are set to INVALID_P2M_ENTRY type (Xen toolstack only
  48  * recognizes that and MFNs, no other fancy value).
  49  *
  50  * On lookup we spot that the entry points to p2m_identity and return the
  51  * identity value instead of dereferencing and returning INVALID_P2M_ENTRY.
  52  * If the entry points to an allocated page, we just proceed as before and
  53  * return the PFN. If the PFN has IDENTITY_FRAME_BIT set we unmask that in
  54  * appropriate functions (pfn_to_mfn).
  55  *
  56  * The reason for having the IDENTITY_FRAME_BIT instead of just returning the
  57  * PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
  58  * non-identity pfn. To protect ourselves against we elect to set (and get) the
  59  * IDENTITY_FRAME_BIT on all identity mapped PFNs.
  60  */
  61
  62 #include <linux/init.h>
  63 #include <linux/module.h>
  64 #include <linux/list.h>
  65 #include <linux/hash.h>
  66 #include <linux/sched.h>
  67 #include <linux/seq_file.h>
  68 #include <linux/bootmem.h>
  69 #include <linux/slab.h>
  70 #include <linux/vmalloc.h>
  71
  72 #include <asm/cache.h>
  73 #include <asm/setup.h>
  74 #include <asm/uaccess.h>
  75
  76 #include <asm/xen/page.h>
  77 #include <asm/xen/hypercall.h>
  78 #include <asm/xen/hypervisor.h>
  79 #include <xen/balloon.h>
  80 #include <xen/grant_table.h>
  81
  82 #include "p2m.h"
  83 #include "multicalls.h"
  84 #include "xen-ops.h"
  85
  86 #define PMDS_PER_MID_PAGE       (P2M_MID_PER_PAGE / PTRS_PER_PTE)
  87
  88 unsigned long *xen_p2m_addr __read_mostly;
  89 EXPORT_SYMBOL_GPL(xen_p2m_addr);
  90 unsigned long xen_p2m_size __read_mostly;
  91 EXPORT_SYMBOL_GPL(xen_p2m_size);
  92 unsigned long xen_max_p2m_pfn __read_mostly;
  93 EXPORT_SYMBOL_GPL(xen_max_p2m_pfn);
  94
  95 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
  96 #define P2M_LIMIT CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
  97 #else
  98 #define P2M_LIMIT 0
  99 #endif
 100
 101 static DEFINE_SPINLOCK(p2m_update_lock);
 102
 103 static unsigned long *p2m_mid_missing_mfn;
 104 static unsigned long *p2m_top_mfn;
 105 static unsigned long **p2m_top_mfn_p;
 106 static unsigned long *p2m_missing;
 107 static unsigned long *p2m_identity;
 108 static pte_t *p2m_missing_pte;
 109 static pte_t *p2m_identity_pte;
 110
 111 static inline unsigned p2m_top_index(unsigned long pfn)
 112 {
 113         BUG_ON(pfn >= MAX_P2M_PFN);
 114         return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
 115 }
 116
 117 static inline unsigned p2m_mid_index(unsigned long pfn)
 118 {
 119         return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
 120 }
 121
 122 static inline unsigned p2m_index(unsigned long pfn)
 123 {
 124         return pfn % P2M_PER_PAGE;
 125 }
 126
 127 static void p2m_top_mfn_init(unsigned long *top)
 128 {
 129         unsigned i;
 130
 131         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
 132                 top[i] = virt_to_mfn(p2m_mid_missing_mfn);
 133 }
 134
 135 static void p2m_top_mfn_p_init(unsigned long **top)
 136 {
 137         unsigned i;
 138
 139         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
 140                 top[i] = p2m_mid_missing_mfn;
 141 }
 142
 143 static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf)
 144 {
 145         unsigned i;
 146
 147         for (i = 0; i < P2M_MID_PER_PAGE; i++)
 148                 mid[i] = virt_to_mfn(leaf);
 149 }
 150
 151 static void p2m_init(unsigned long *p2m)
 152 {
 153         unsigned i;
 154
 155         for (i = 0; i < P2M_PER_PAGE; i++)
 156                 p2m[i] = INVALID_P2M_ENTRY;
 157 }
 158
 159 static void p2m_init_identity(unsigned long *p2m, unsigned long pfn)
 160 {
 161         unsigned i;
 162
 163         for (i = 0; i < P2M_PER_PAGE; i++)
 164                 p2m[i] = IDENTITY_FRAME(pfn + i);
 165 }
 166
 167 static void * __ref alloc_p2m_page(void)
 168 {
 169         if (unlikely(!slab_is_available()))
 170                 return alloc_bootmem_align(PAGE_SIZE, PAGE_SIZE);
 171
 172         return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT);
 173 }
 174
 175 static void __ref free_p2m_page(void *p)
 176 {
 177         if (unlikely(!slab_is_available())) {
 178                 free_bootmem((unsigned long)p, PAGE_SIZE);
 179                 return;
 180         }
 181
 182         free_page((unsigned long)p);
 183 }
 184
 185 /*
 186  * Build the parallel p2m_top_mfn and p2m_mid_mfn structures
 187  *
 188  * This is called both at boot time, and after resuming from suspend:
 189  * - At boot time we're called rather early, and must use alloc_bootmem*()
 190  *   to allocate memory.
 191  *
 192  * - After resume we're called from within stop_machine, but the mfn
 193  *   tree should already be completely allocated.
 194  */
 195 void __ref xen_build_mfn_list_list(void)
 196 {
 197         unsigned long pfn, mfn;
 198         pte_t *ptep;
 199         unsigned int level, topidx, mididx;
 200         unsigned long *mid_mfn_p;
 201
 202         if (xen_feature(XENFEAT_auto_translated_physmap))
 203                 return;
 204
 205         /* Pre-initialize p2m_top_mfn to be completely missing */
 206         if (p2m_top_mfn == NULL) {
 207                 p2m_mid_missing_mfn = alloc_p2m_page();
 208                 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
 209
 210                 p2m_top_mfn_p = alloc_p2m_page();
 211                 p2m_top_mfn_p_init(p2m_top_mfn_p);
 212
 213                 p2m_top_mfn = alloc_p2m_page();
 214                 p2m_top_mfn_init(p2m_top_mfn);
 215         } else {
 216                 /* Reinitialise, mfn's all change after migration */
 217                 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
 218         }
 219
 220         for (pfn = 0; pfn < xen_max_p2m_pfn && pfn < MAX_P2M_PFN;
 221              pfn += P2M_PER_PAGE) {
 222                 topidx = p2m_top_index(pfn);
 223                 mididx = p2m_mid_index(pfn);
 224
 225                 mid_mfn_p = p2m_top_mfn_p[topidx];
 226                 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn),
 227                                       &level);
 228                 BUG_ON(!ptep || level != PG_LEVEL_4K);
 229                 mfn = pte_mfn(*ptep);
 230                 ptep = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
 231
 232                 /* Don't bother allocating any mfn mid levels if
 233                  * they're just missing, just update the stored mfn,
 234                  * since all could have changed over a migrate.
 235                  */
 236                 if (ptep == p2m_missing_pte || ptep == p2m_identity_pte) {
 237                         BUG_ON(mididx);
 238                         BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
 239                         p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
 240                         pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
 241                         continue;
 242                 }
 243
 244                 if (mid_mfn_p == p2m_mid_missing_mfn) {
 245                         mid_mfn_p = alloc_p2m_page();
 246                         p2m_mid_mfn_init(mid_mfn_p, p2m_missing);
 247
 248                         p2m_top_mfn_p[topidx] = mid_mfn_p;
 249                 }
 250
 251                 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
 252                 mid_mfn_p[mididx] = mfn;
 253         }
 254 }
 255
 256 void xen_setup_mfn_list_list(void)
 257 {
 258         if (xen_feature(XENFEAT_auto_translated_physmap))
 259                 return;
 260
 261         BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
 262
 263         HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
 264                 virt_to_mfn(p2m_top_mfn);
 265         HYPERVISOR_shared_info->arch.max_pfn = xen_max_p2m_pfn;
 266 }
 267
 268 /* Set up p2m_top to point to the domain-builder provided p2m pages */
 269 void __init xen_build_dynamic_phys_to_machine(void)
 270 {
 271         unsigned long pfn;
 272
 273          if (xen_feature(XENFEAT_auto_translated_physmap))
 274                 return;
 275
 276         xen_p2m_addr = (unsigned long *)xen_start_info->mfn_list;
 277         xen_p2m_size = ALIGN(xen_start_info->nr_pages, P2M_PER_PAGE);
 278
 279         for (pfn = xen_start_info->nr_pages; pfn < xen_p2m_size; pfn++)
 280                 xen_p2m_addr[pfn] = INVALID_P2M_ENTRY;
 281
 282         xen_max_p2m_pfn = xen_p2m_size;
 283 }
 284
 285 #define P2M_TYPE_IDENTITY       0
 286 #define P2M_TYPE_MISSING        1
 287 #define P2M_TYPE_PFN            2
 288 #define P2M_TYPE_UNKNOWN        3
 289
 290 static int xen_p2m_elem_type(unsigned long pfn)
 291 {
 292         unsigned long mfn;
 293
 294         if (pfn >= xen_p2m_size)
 295                 return P2M_TYPE_IDENTITY;
 296
 297         mfn = xen_p2m_addr[pfn];
 298
 299         if (mfn == INVALID_P2M_ENTRY)
 300                 return P2M_TYPE_MISSING;
 301
 302         if (mfn & IDENTITY_FRAME_BIT)
 303                 return P2M_TYPE_IDENTITY;
 304
 305         return P2M_TYPE_PFN;
 306 }
 307
 308 static void __init xen_rebuild_p2m_list(unsigned long *p2m)
 309 {
 310         unsigned int i, chunk;
 311         unsigned long pfn;
 312         unsigned long *mfns;
 313         pte_t *ptep;
 314         pmd_t *pmdp;
 315         int type;
 316
 317         p2m_missing = alloc_p2m_page();
 318         p2m_init(p2m_missing);
 319         p2m_identity = alloc_p2m_page();
 320         p2m_init(p2m_identity);
 321
 322         p2m_missing_pte = alloc_p2m_page();
 323         paravirt_alloc_pte(&init_mm, __pa(p2m_missing_pte) >> PAGE_SHIFT);
 324         p2m_identity_pte = alloc_p2m_page();
 325         paravirt_alloc_pte(&init_mm, __pa(p2m_identity_pte) >> PAGE_SHIFT);
 326         for (i = 0; i < PTRS_PER_PTE; i++) {
 327                 set_pte(p2m_missing_pte + i,
 328                         pfn_pte(PFN_DOWN(__pa(p2m_missing)), PAGE_KERNEL_RO));
 329                 set_pte(p2m_identity_pte + i,
 330                         pfn_pte(PFN_DOWN(__pa(p2m_identity)), PAGE_KERNEL_RO));
 331         }
 332
 333         for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += chunk) {
 334                 /*
 335                  * Try to map missing/identity PMDs or p2m-pages if possible.
 336                  * We have to respect the structure of the mfn_list_list
 337                  * which will be built just afterwards.
 338                  * Chunk size to test is one p2m page if we are in the middle
 339                  * of a mfn_list_list mid page and the complete mid page area
 340                  * if we are at index 0 of the mid page. Please note that a
 341                  * mid page might cover more than one PMD, e.g. on 32 bit PAE
 342                  * kernels.
 343                  */
 344                 chunk = (pfn & (P2M_PER_PAGE * P2M_MID_PER_PAGE - 1)) ?
 345                         P2M_PER_PAGE : P2M_PER_PAGE * P2M_MID_PER_PAGE;
 346
 347                 type = xen_p2m_elem_type(pfn);
 348                 i = 0;
 349                 if (type != P2M_TYPE_PFN)
 350                         for (i = 1; i < chunk; i++)
 351                                 if (xen_p2m_elem_type(pfn + i) != type)
 352                                         break;
 353                 if (i < chunk)
 354                         /* Reset to minimal chunk size. */
 355                         chunk = P2M_PER_PAGE;
 356
 357                 if (type == P2M_TYPE_PFN || i < chunk) {
 358                         /* Use initial p2m page contents. */
 359 #ifdef CONFIG_X86_64
 360                         mfns = alloc_p2m_page();
 361                         copy_page(mfns, xen_p2m_addr + pfn);
 362 #else
 363                         mfns = xen_p2m_addr + pfn;
 364 #endif
 365                         ptep = populate_extra_pte((unsigned long)(p2m + pfn));
 366                         set_pte(ptep,
 367                                 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL));
 368                         continue;
 369                 }
 370
 371                 if (chunk == P2M_PER_PAGE) {
 372                         /* Map complete missing or identity p2m-page. */
 373                         mfns = (type == P2M_TYPE_MISSING) ?
 374                                 p2m_missing : p2m_identity;
 375                         ptep = populate_extra_pte((unsigned long)(p2m + pfn));
 376                         set_pte(ptep,
 377                                 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL_RO));
 378                         continue;
 379                 }
 380
 381                 /* Complete missing or identity PMD(s) can be mapped. */
 382                 ptep = (type == P2M_TYPE_MISSING) ?
 383                         p2m_missing_pte : p2m_identity_pte;
 384                 for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
 385                         pmdp = populate_extra_pmd(
 386                                 (unsigned long)(p2m + pfn) + i * PMD_SIZE);
 387                         set_pmd(pmdp, __pmd(__pa(ptep) | _KERNPG_TABLE));
 388                 }
 389         }
 390 }
 391
 392 void __init xen_vmalloc_p2m_tree(void)
 393 {
 394         static struct vm_struct vm;
 395         unsigned long p2m_limit;
 396
 397         p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE;
 398         vm.flags = VM_ALLOC;
 399         vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit),
 400                         PMD_SIZE * PMDS_PER_MID_PAGE);
 401         vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE);
 402         pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size);
 403
 404         xen_max_p2m_pfn = vm.size / sizeof(unsigned long);
 405
 406         xen_rebuild_p2m_list(vm.addr);
 407
 408         xen_p2m_addr = vm.addr;
 409         xen_p2m_size = xen_max_p2m_pfn;
 410
 411         xen_inv_extra_mem();
 412 }
 413
 414 unsigned long get_phys_to_machine(unsigned long pfn)
 415 {
 416         pte_t *ptep;
 417         unsigned int level;
 418
 419         if (unlikely(pfn >= xen_p2m_size)) {
 420                 if (pfn < xen_max_p2m_pfn)
 421                         return xen_chk_extra_mem(pfn);
 422
 423                 return IDENTITY_FRAME(pfn);
 424         }
 425
 426         ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
 427         BUG_ON(!ptep || level != PG_LEVEL_4K);
 428
 429         /*
 430          * The INVALID_P2M_ENTRY is filled in both p2m_*identity
 431          * and in p2m_*missing, so returning the INVALID_P2M_ENTRY
 432          * would be wrong.
 433          */
 434         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
 435                 return IDENTITY_FRAME(pfn);
 436
 437         return xen_p2m_addr[pfn];
 438 }
 439 EXPORT_SYMBOL_GPL(get_phys_to_machine);
 440
 441 /*
 442  * Allocate new pmd(s). It is checked whether the old pmd is still in place.
 443  * If not, nothing is changed. This is okay as the only reason for allocating
 444  * a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual
 445  * pmd. In case of PAE/x86-32 there are multiple pmds to allocate!
 446  */
 447 static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg)
 448 {
 449         pte_t *ptechk;
 450         pte_t *pte_newpg[PMDS_PER_MID_PAGE];
 451         pmd_t *pmdp;
 452         unsigned int level;
 453         unsigned long flags;
 454         unsigned long vaddr;
 455         int i;
 456
 457         /* Do all allocations first to bail out in error case. */
 458         for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
 459                 pte_newpg[i] = alloc_p2m_page();
 460                 if (!pte_newpg[i]) {
 461                         for (i--; i >= 0; i--)
 462                                 free_p2m_page(pte_newpg[i]);
 463
 464                         return NULL;
 465                 }
 466         }
 467
 468         vaddr = addr & ~(PMD_SIZE * PMDS_PER_MID_PAGE - 1);
 469
 470         for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
 471                 copy_page(pte_newpg[i], pte_pg);
 472                 paravirt_alloc_pte(&init_mm, __pa(pte_newpg[i]) >> PAGE_SHIFT);
 473
 474                 pmdp = lookup_pmd_address(vaddr);
 475                 BUG_ON(!pmdp);
 476
 477                 spin_lock_irqsave(&p2m_update_lock, flags);
 478
 479                 ptechk = lookup_address(vaddr, &level);
 480                 if (ptechk == pte_pg) {
 481                         set_pmd(pmdp,
 482                                 __pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE));
 483                         pte_newpg[i] = NULL;
 484                 }
 485
 486                 spin_unlock_irqrestore(&p2m_update_lock, flags);
 487
 488                 if (pte_newpg[i]) {
 489                         paravirt_release_pte(__pa(pte_newpg[i]) >> PAGE_SHIFT);
 490                         free_p2m_page(pte_newpg[i]);
 491                 }
 492
 493                 vaddr += PMD_SIZE;
 494         }
 495
 496         return lookup_address(addr, &level);
 497 }
 498
 499 /*
 500  * Fully allocate the p2m structure for a given pfn.  We need to check
 501  * that both the top and mid levels are allocated, and make sure the
 502  * parallel mfn tree is kept in sync.  We may race with other cpus, so
 503  * the new pages are installed with cmpxchg; if we lose the race then
 504  * simply free the page we allocated and use the one that's there.
 505  */
 506 static bool alloc_p2m(unsigned long pfn)
 507 {
 508         unsigned topidx, mididx;
 509         unsigned long *top_mfn_p, *mid_mfn;
 510         pte_t *ptep, *pte_pg;
 511         unsigned int level;
 512         unsigned long flags;
 513         unsigned long addr = (unsigned long)(xen_p2m_addr + pfn);
 514         unsigned long p2m_pfn;
 515
 516         topidx = p2m_top_index(pfn);
 517         mididx = p2m_mid_index(pfn);
 518
 519         ptep = lookup_address(addr, &level);
 520         BUG_ON(!ptep || level != PG_LEVEL_4K);
 521         pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
 522
 523         if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) {
 524                 /* PMD level is missing, allocate a new one */
 525                 ptep = alloc_p2m_pmd(addr, pte_pg);
 526                 if (!ptep)
 527                         return false;
 528         }
 529
 530         if (p2m_top_mfn) {
 531                 top_mfn_p = &p2m_top_mfn[topidx];
 532                 mid_mfn = ACCESS_ONCE(p2m_top_mfn_p[topidx]);
 533
 534                 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
 535
 536                 if (mid_mfn == p2m_mid_missing_mfn) {
 537                         /* Separately check the mid mfn level */
 538                         unsigned long missing_mfn;
 539                         unsigned long mid_mfn_mfn;
 540                         unsigned long old_mfn;
 541
 542                         mid_mfn = alloc_p2m_page();
 543                         if (!mid_mfn)
 544                                 return false;
 545
 546                         p2m_mid_mfn_init(mid_mfn, p2m_missing);
 547
 548                         missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
 549                         mid_mfn_mfn = virt_to_mfn(mid_mfn);
 550                         old_mfn = cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn);
 551                         if (old_mfn != missing_mfn) {
 552                                 free_p2m_page(mid_mfn);
 553                                 mid_mfn = mfn_to_virt(old_mfn);
 554                         } else {
 555                                 p2m_top_mfn_p[topidx] = mid_mfn;
 556                         }
 557                 }
 558         } else {
 559                 mid_mfn = NULL;
 560         }
 561
 562         p2m_pfn = pte_pfn(READ_ONCE(*ptep));
 563         if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) ||
 564             p2m_pfn == PFN_DOWN(__pa(p2m_missing))) {
 565                 /* p2m leaf page is missing */
 566                 unsigned long *p2m;
 567
 568                 p2m = alloc_p2m_page();
 569                 if (!p2m)
 570                         return false;
 571
 572                 if (p2m_pfn == PFN_DOWN(__pa(p2m_missing)))
 573                         p2m_init(p2m);
 574                 else
 575                         p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1));
 576
 577                 spin_lock_irqsave(&p2m_update_lock, flags);
 578
 579                 if (pte_pfn(*ptep) == p2m_pfn) {
 580                         set_pte(ptep,
 581                                 pfn_pte(PFN_DOWN(__pa(p2m)), PAGE_KERNEL));
 582                         if (mid_mfn)
 583                                 mid_mfn[mididx] = virt_to_mfn(p2m);
 584                         p2m = NULL;
 585                 }
 586
 587                 spin_unlock_irqrestore(&p2m_update_lock, flags);
 588
 589                 if (p2m)
 590                         free_p2m_page(p2m);
 591         }
 592
 593         return true;
 594 }
 595
 596 unsigned long __init set_phys_range_identity(unsigned long pfn_s,
 597                                       unsigned long pfn_e)
 598 {
 599         unsigned long pfn;
 600
 601         if (unlikely(pfn_s >= xen_p2m_size))
 602                 return 0;
 603
 604         if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
 605                 return pfn_e - pfn_s;
 606
 607         if (pfn_s > pfn_e)
 608                 return 0;
 609
 610         if (pfn_e > xen_p2m_size)
 611                 pfn_e = xen_p2m_size;
 612
 613         for (pfn = pfn_s; pfn < pfn_e; pfn++)
 614                 xen_p2m_addr[pfn] = IDENTITY_FRAME(pfn);
 615
 616         return pfn - pfn_s;
 617 }
 618
 619 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 620 {
 621         pte_t *ptep;
 622         unsigned int level;
 623
 624         /* don't track P2M changes in autotranslate guests */
 625         if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
 626                 return true;
 627
 628         if (unlikely(pfn >= xen_p2m_size)) {
 629                 BUG_ON(mfn != INVALID_P2M_ENTRY);
 630                 return true;
 631         }
 632
 633         if (likely(!xen_safe_write_ulong(xen_p2m_addr + pfn, mfn)))
 634                 return true;
 635
 636         ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
 637         BUG_ON(!ptep || level != PG_LEVEL_4K);
 638
 639         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_missing)))
 640                 return mfn == INVALID_P2M_ENTRY;
 641
 642         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
 643                 return mfn == IDENTITY_FRAME(pfn);
 644
 645         return false;
 646 }
 647
 648 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 649 {
 650         if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
 651                 if (!alloc_p2m(pfn))
 652                         return false;
 653
 654                 return __set_phys_to_machine(pfn, mfn);
 655         }
 656
 657         return true;
 658 }
 659
 660 int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
 661                             struct gnttab_map_grant_ref *kmap_ops,
 662                             struct page **pages, unsigned int count)
 663 {
 664         int i, ret = 0;
 665         pte_t *pte;
 666
 667         if (xen_feature(XENFEAT_auto_translated_physmap))
 668                 return 0;
 669
 670         if (kmap_ops) {
 671                 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
 672                                                 kmap_ops, count);
 673                 if (ret)
 674                         goto out;
 675         }
 676
 677         for (i = 0; i < count; i++) {
 678                 unsigned long mfn, pfn;
 679
 680                 /* Do not add to override if the map failed. */
 681                 if (map_ops[i].status)
 682                         continue;
 683
 684                 if (map_ops[i].flags & GNTMAP_contains_pte) {
 685                         pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
 686                                 (map_ops[i].host_addr & ~PAGE_MASK));
 687                         mfn = pte_mfn(*pte);
 688                 } else {
 689                         mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
 690                 }
 691                 pfn = page_to_pfn(pages[i]);
 692
 693                 WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned");
 694
 695                 if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
 696                         ret = -ENOMEM;
 697                         goto out;
 698                 }
 699         }
 700
 701 out:
 702         return ret;
 703 }
 704 EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping);
 705
 706 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
 707                               struct gnttab_unmap_grant_ref *kunmap_ops,
 708                               struct page **pages, unsigned int count)
 709 {
 710         int i, ret = 0;
 711
 712         if (xen_feature(XENFEAT_auto_translated_physmap))
 713                 return 0;
 714
 715         for (i = 0; i < count; i++) {
 716                 unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i]));
 717                 unsigned long pfn = page_to_pfn(pages[i]);
 718
 719                 if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) {
 720                         ret = -EINVAL;
 721                         goto out;
 722                 }
 723
 724                 set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
 725         }
 726         if (kunmap_ops)
 727                 ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
 728                                                 kunmap_ops, count);
 729 out:
 730         return ret;
 731 }
 732 EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);
 733
 734 #ifdef CONFIG_XEN_DEBUG_FS
 735 #include <linux/debugfs.h>
 736 #include "debugfs.h"
 737 static int p2m_dump_show(struct seq_file *m, void *v)
 738 {
 739         static const char * const type_name[] = {
 740                                 [P2M_TYPE_IDENTITY] = "identity",
 741                                 [P2M_TYPE_MISSING] = "missing",
 742                                 [P2M_TYPE_PFN] = "pfn",
 743                                 [P2M_TYPE_UNKNOWN] = "abnormal"};
 744         unsigned long pfn, first_pfn;
 745         int type, prev_type;
 746
 747         prev_type = xen_p2m_elem_type(0);
 748         first_pfn = 0;
 749
 750         for (pfn = 0; pfn < xen_p2m_size; pfn++) {
 751                 type = xen_p2m_elem_type(pfn);
 752                 if (type != prev_type) {
 753                         seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
 754                                    type_name[prev_type]);
 755                         prev_type = type;
 756                         first_pfn = pfn;
 757                 }
 758         }
 759         seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
 760                    type_name[prev_type]);
 761         return 0;
 762 }
 763
 764 static int p2m_dump_open(struct inode *inode, struct file *filp)
 765 {
 766         return single_open(filp, p2m_dump_show, NULL);
 767 }
 768
 769 static const struct file_operations p2m_dump_fops = {
 770         .open           = p2m_dump_open,
 771         .read           = seq_read,
 772         .llseek         = seq_lseek,
 773         .release        = single_release,
 774 };
 775
 776 static struct dentry *d_mmu_debug;
 777
 778 static int __init xen_p2m_debugfs(void)
 779 {
 780         struct dentry *d_xen = xen_init_debugfs();
 781
 782         if (d_xen == NULL)
 783                 return -ENOMEM;
 784
 785         d_mmu_debug = debugfs_create_dir("mmu", d_xen);
 786
 787         debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops);
 788         return 0;
 789 }
 790 fs_initcall(xen_p2m_debugfs);
 791 #endif /* CONFIG_XEN_DEBUG_FS */