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 "multicalls.h"
  83 #include "xen-ops.h"
  84
  85 #define P2M_MID_PER_PAGE        (PAGE_SIZE / sizeof(unsigned long *))
  86 #define P2M_TOP_PER_PAGE        (PAGE_SIZE / sizeof(unsigned long **))
  87
  88 #define MAX_P2M_PFN     (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE)
  89
  90 #define PMDS_PER_MID_PAGE       (P2M_MID_PER_PAGE / PTRS_PER_PTE)
  91
  92 unsigned long *xen_p2m_addr __read_mostly;
  93 EXPORT_SYMBOL_GPL(xen_p2m_addr);
  94 unsigned long xen_p2m_size __read_mostly;
  95 EXPORT_SYMBOL_GPL(xen_p2m_size);
  96 unsigned long xen_max_p2m_pfn __read_mostly;
  97 EXPORT_SYMBOL_GPL(xen_max_p2m_pfn);
  98
  99 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
 100 #define P2M_LIMIT CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
 101 #else
 102 #define P2M_LIMIT 0
 103 #endif
 104
 105 static DEFINE_SPINLOCK(p2m_update_lock);
 106
 107 static unsigned long *p2m_mid_missing_mfn;
 108 static unsigned long *p2m_top_mfn;
 109 static unsigned long **p2m_top_mfn_p;
 110 static unsigned long *p2m_missing;
 111 static unsigned long *p2m_identity;
 112 static pte_t *p2m_missing_pte;
 113 static pte_t *p2m_identity_pte;
 114
 115 /*
 116  * Hint at last populated PFN.
 117  *
 118  * Used to set HYPERVISOR_shared_info->arch.max_pfn so the toolstack
 119  * can avoid scanning the whole P2M (which may be sized to account for
 120  * hotplugged memory).
 121  */
 122 static unsigned long xen_p2m_last_pfn;
 123
 124 static inline unsigned p2m_top_index(unsigned long pfn)
 125 {
 126         BUG_ON(pfn >= MAX_P2M_PFN);
 127         return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
 128 }
 129
 130 static inline unsigned p2m_mid_index(unsigned long pfn)
 131 {
 132         return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
 133 }
 134
 135 static inline unsigned p2m_index(unsigned long pfn)
 136 {
 137         return pfn % P2M_PER_PAGE;
 138 }
 139
 140 static void p2m_top_mfn_init(unsigned long *top)
 141 {
 142         unsigned i;
 143
 144         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
 145                 top[i] = virt_to_mfn(p2m_mid_missing_mfn);
 146 }
 147
 148 static void p2m_top_mfn_p_init(unsigned long **top)
 149 {
 150         unsigned i;
 151
 152         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
 153                 top[i] = p2m_mid_missing_mfn;
 154 }
 155
 156 static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf)
 157 {
 158         unsigned i;
 159
 160         for (i = 0; i < P2M_MID_PER_PAGE; i++)
 161                 mid[i] = virt_to_mfn(leaf);
 162 }
 163
 164 static void p2m_init(unsigned long *p2m)
 165 {
 166         unsigned i;
 167
 168         for (i = 0; i < P2M_PER_PAGE; i++)
 169                 p2m[i] = INVALID_P2M_ENTRY;
 170 }
 171
 172 static void p2m_init_identity(unsigned long *p2m, unsigned long pfn)
 173 {
 174         unsigned i;
 175
 176         for (i = 0; i < P2M_PER_PAGE; i++)
 177                 p2m[i] = IDENTITY_FRAME(pfn + i);
 178 }
 179
 180 static void * __ref alloc_p2m_page(void)
 181 {
 182         if (unlikely(!slab_is_available()))
 183                 return alloc_bootmem_align(PAGE_SIZE, PAGE_SIZE);
 184
 185         return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT);
 186 }
 187
 188 static void __ref free_p2m_page(void *p)
 189 {
 190         if (unlikely(!slab_is_available())) {
 191                 free_bootmem((unsigned long)p, PAGE_SIZE);
 192                 return;
 193         }
 194
 195         free_page((unsigned long)p);
 196 }
 197
 198 /*
 199  * Build the parallel p2m_top_mfn and p2m_mid_mfn structures
 200  *
 201  * This is called both at boot time, and after resuming from suspend:
 202  * - At boot time we're called rather early, and must use alloc_bootmem*()
 203  *   to allocate memory.
 204  *
 205  * - After resume we're called from within stop_machine, but the mfn
 206  *   tree should already be completely allocated.
 207  */
 208 void __ref xen_build_mfn_list_list(void)
 209 {
 210         unsigned long pfn, mfn;
 211         pte_t *ptep;
 212         unsigned int level, topidx, mididx;
 213         unsigned long *mid_mfn_p;
 214
 215         if (xen_feature(XENFEAT_auto_translated_physmap) ||
 216             xen_start_info->flags & SIF_VIRT_P2M_4TOOLS)
 217                 return;
 218
 219         /* Pre-initialize p2m_top_mfn to be completely missing */
 220         if (p2m_top_mfn == NULL) {
 221                 p2m_mid_missing_mfn = alloc_p2m_page();
 222                 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
 223
 224                 p2m_top_mfn_p = alloc_p2m_page();
 225                 p2m_top_mfn_p_init(p2m_top_mfn_p);
 226
 227                 p2m_top_mfn = alloc_p2m_page();
 228                 p2m_top_mfn_init(p2m_top_mfn);
 229         } else {
 230                 /* Reinitialise, mfn's all change after migration */
 231                 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
 232         }
 233
 234         for (pfn = 0; pfn < xen_max_p2m_pfn && pfn < MAX_P2M_PFN;
 235              pfn += P2M_PER_PAGE) {
 236                 topidx = p2m_top_index(pfn);
 237                 mididx = p2m_mid_index(pfn);
 238
 239                 mid_mfn_p = p2m_top_mfn_p[topidx];
 240                 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn),
 241                                       &level);
 242                 BUG_ON(!ptep || level != PG_LEVEL_4K);
 243                 mfn = pte_mfn(*ptep);
 244                 ptep = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
 245
 246                 /* Don't bother allocating any mfn mid levels if
 247                  * they're just missing, just update the stored mfn,
 248                  * since all could have changed over a migrate.
 249                  */
 250                 if (ptep == p2m_missing_pte || ptep == p2m_identity_pte) {
 251                         BUG_ON(mididx);
 252                         BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
 253                         p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
 254                         pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
 255                         continue;
 256                 }
 257
 258                 if (mid_mfn_p == p2m_mid_missing_mfn) {
 259                         mid_mfn_p = alloc_p2m_page();
 260                         p2m_mid_mfn_init(mid_mfn_p, p2m_missing);
 261
 262                         p2m_top_mfn_p[topidx] = mid_mfn_p;
 263                 }
 264
 265                 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
 266                 mid_mfn_p[mididx] = mfn;
 267         }
 268 }
 269
 270 void xen_setup_mfn_list_list(void)
 271 {
 272         if (xen_feature(XENFEAT_auto_translated_physmap))
 273                 return;
 274
 275         BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
 276
 277         if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS)
 278                 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = ~0UL;
 279         else
 280                 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
 281                         virt_to_mfn(p2m_top_mfn);
 282         HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn;
 283         HYPERVISOR_shared_info->arch.p2m_generation = 0;
 284         HYPERVISOR_shared_info->arch.p2m_vaddr = (unsigned long)xen_p2m_addr;
 285         HYPERVISOR_shared_info->arch.p2m_cr3 =
 286                 xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
 287 }
 288
 289 /* Set up p2m_top to point to the domain-builder provided p2m pages */
 290 void __init xen_build_dynamic_phys_to_machine(void)
 291 {
 292         unsigned long pfn;
 293
 294          if (xen_feature(XENFEAT_auto_translated_physmap))
 295                 return;
 296
 297         xen_p2m_addr = (unsigned long *)xen_start_info->mfn_list;
 298         xen_p2m_size = ALIGN(xen_start_info->nr_pages, P2M_PER_PAGE);
 299
 300         for (pfn = xen_start_info->nr_pages; pfn < xen_p2m_size; pfn++)
 301                 xen_p2m_addr[pfn] = INVALID_P2M_ENTRY;
 302
 303         xen_max_p2m_pfn = xen_p2m_size;
 304 }
 305
 306 #define P2M_TYPE_IDENTITY       0
 307 #define P2M_TYPE_MISSING        1
 308 #define P2M_TYPE_PFN            2
 309 #define P2M_TYPE_UNKNOWN        3
 310
 311 static int xen_p2m_elem_type(unsigned long pfn)
 312 {
 313         unsigned long mfn;
 314
 315         if (pfn >= xen_p2m_size)
 316                 return P2M_TYPE_IDENTITY;
 317
 318         mfn = xen_p2m_addr[pfn];
 319
 320         if (mfn == INVALID_P2M_ENTRY)
 321                 return P2M_TYPE_MISSING;
 322
 323         if (mfn & IDENTITY_FRAME_BIT)
 324                 return P2M_TYPE_IDENTITY;
 325
 326         return P2M_TYPE_PFN;
 327 }
 328
 329 static void __init xen_rebuild_p2m_list(unsigned long *p2m)
 330 {
 331         unsigned int i, chunk;
 332         unsigned long pfn;
 333         unsigned long *mfns;
 334         pte_t *ptep;
 335         pmd_t *pmdp;
 336         int type;
 337
 338         p2m_missing = alloc_p2m_page();
 339         p2m_init(p2m_missing);
 340         p2m_identity = alloc_p2m_page();
 341         p2m_init(p2m_identity);
 342
 343         p2m_missing_pte = alloc_p2m_page();
 344         paravirt_alloc_pte(&init_mm, __pa(p2m_missing_pte) >> PAGE_SHIFT);
 345         p2m_identity_pte = alloc_p2m_page();
 346         paravirt_alloc_pte(&init_mm, __pa(p2m_identity_pte) >> PAGE_SHIFT);
 347         for (i = 0; i < PTRS_PER_PTE; i++) {
 348                 set_pte(p2m_missing_pte + i,
 349                         pfn_pte(PFN_DOWN(__pa(p2m_missing)), PAGE_KERNEL_RO));
 350                 set_pte(p2m_identity_pte + i,
 351                         pfn_pte(PFN_DOWN(__pa(p2m_identity)), PAGE_KERNEL_RO));
 352         }
 353
 354         for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += chunk) {
 355                 /*
 356                  * Try to map missing/identity PMDs or p2m-pages if possible.
 357                  * We have to respect the structure of the mfn_list_list
 358                  * which will be built just afterwards.
 359                  * Chunk size to test is one p2m page if we are in the middle
 360                  * of a mfn_list_list mid page and the complete mid page area
 361                  * if we are at index 0 of the mid page. Please note that a
 362                  * mid page might cover more than one PMD, e.g. on 32 bit PAE
 363                  * kernels.
 364                  */
 365                 chunk = (pfn & (P2M_PER_PAGE * P2M_MID_PER_PAGE - 1)) ?
 366                         P2M_PER_PAGE : P2M_PER_PAGE * P2M_MID_PER_PAGE;
 367
 368                 type = xen_p2m_elem_type(pfn);
 369                 i = 0;
 370                 if (type != P2M_TYPE_PFN)
 371                         for (i = 1; i < chunk; i++)
 372                                 if (xen_p2m_elem_type(pfn + i) != type)
 373                                         break;
 374                 if (i < chunk)
 375                         /* Reset to minimal chunk size. */
 376                         chunk = P2M_PER_PAGE;
 377
 378                 if (type == P2M_TYPE_PFN || i < chunk) {
 379                         /* Use initial p2m page contents. */
 380 #ifdef CONFIG_X86_64
 381                         mfns = alloc_p2m_page();
 382                         copy_page(mfns, xen_p2m_addr + pfn);
 383 #else
 384                         mfns = xen_p2m_addr + pfn;
 385 #endif
 386                         ptep = populate_extra_pte((unsigned long)(p2m + pfn));
 387                         set_pte(ptep,
 388                                 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL));
 389                         continue;
 390                 }
 391
 392                 if (chunk == P2M_PER_PAGE) {
 393                         /* Map complete missing or identity p2m-page. */
 394                         mfns = (type == P2M_TYPE_MISSING) ?
 395                                 p2m_missing : p2m_identity;
 396                         ptep = populate_extra_pte((unsigned long)(p2m + pfn));
 397                         set_pte(ptep,
 398                                 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL_RO));
 399                         continue;
 400                 }
 401
 402                 /* Complete missing or identity PMD(s) can be mapped. */
 403                 ptep = (type == P2M_TYPE_MISSING) ?
 404                         p2m_missing_pte : p2m_identity_pte;
 405                 for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
 406                         pmdp = populate_extra_pmd(
 407                                 (unsigned long)(p2m + pfn) + i * PMD_SIZE);
 408                         set_pmd(pmdp, __pmd(__pa(ptep) | _KERNPG_TABLE));
 409                 }
 410         }
 411 }
 412
 413 void __init xen_vmalloc_p2m_tree(void)
 414 {
 415         static struct vm_struct vm;
 416         unsigned long p2m_limit;
 417
 418         xen_p2m_last_pfn = xen_max_p2m_pfn;
 419
 420         p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE;
 421         vm.flags = VM_ALLOC;
 422         vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit),
 423                         PMD_SIZE * PMDS_PER_MID_PAGE);
 424         vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE);
 425         pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size);
 426
 427         xen_max_p2m_pfn = vm.size / sizeof(unsigned long);
 428
 429         xen_rebuild_p2m_list(vm.addr);
 430
 431         xen_p2m_addr = vm.addr;
 432         xen_p2m_size = xen_max_p2m_pfn;
 433
 434         xen_inv_extra_mem();
 435 }
 436
 437 unsigned long get_phys_to_machine(unsigned long pfn)
 438 {
 439         pte_t *ptep;
 440         unsigned int level;
 441
 442         if (unlikely(pfn >= xen_p2m_size)) {
 443                 if (pfn < xen_max_p2m_pfn)
 444                         return xen_chk_extra_mem(pfn);
 445
 446                 return IDENTITY_FRAME(pfn);
 447         }
 448
 449         ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
 450         BUG_ON(!ptep || level != PG_LEVEL_4K);
 451
 452         /*
 453          * The INVALID_P2M_ENTRY is filled in both p2m_*identity
 454          * and in p2m_*missing, so returning the INVALID_P2M_ENTRY
 455          * would be wrong.
 456          */
 457         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
 458                 return IDENTITY_FRAME(pfn);
 459
 460         return xen_p2m_addr[pfn];
 461 }
 462 EXPORT_SYMBOL_GPL(get_phys_to_machine);
 463
 464 /*
 465  * Allocate new pmd(s). It is checked whether the old pmd is still in place.
 466  * If not, nothing is changed. This is okay as the only reason for allocating
 467  * a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual
 468  * pmd. In case of PAE/x86-32 there are multiple pmds to allocate!
 469  */
 470 static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg)
 471 {
 472         pte_t *ptechk;
 473         pte_t *pte_newpg[PMDS_PER_MID_PAGE];
 474         pmd_t *pmdp;
 475         unsigned int level;
 476         unsigned long flags;
 477         unsigned long vaddr;
 478         int i;
 479
 480         /* Do all allocations first to bail out in error case. */
 481         for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
 482                 pte_newpg[i] = alloc_p2m_page();
 483                 if (!pte_newpg[i]) {
 484                         for (i--; i >= 0; i--)
 485                                 free_p2m_page(pte_newpg[i]);
 486
 487                         return NULL;
 488                 }
 489         }
 490
 491         vaddr = addr & ~(PMD_SIZE * PMDS_PER_MID_PAGE - 1);
 492
 493         for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
 494                 copy_page(pte_newpg[i], pte_pg);
 495                 paravirt_alloc_pte(&init_mm, __pa(pte_newpg[i]) >> PAGE_SHIFT);
 496
 497                 pmdp = lookup_pmd_address(vaddr);
 498                 BUG_ON(!pmdp);
 499
 500                 spin_lock_irqsave(&p2m_update_lock, flags);
 501
 502                 ptechk = lookup_address(vaddr, &level);
 503                 if (ptechk == pte_pg) {
 504                         HYPERVISOR_shared_info->arch.p2m_generation++;
 505                         wmb(); /* Tools are synchronizing via p2m_generation. */
 506                         set_pmd(pmdp,
 507                                 __pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE));
 508                         wmb(); /* Tools are synchronizing via p2m_generation. */
 509                         HYPERVISOR_shared_info->arch.p2m_generation++;
 510                         pte_newpg[i] = NULL;
 511                 }
 512
 513                 spin_unlock_irqrestore(&p2m_update_lock, flags);
 514
 515                 if (pte_newpg[i]) {
 516                         paravirt_release_pte(__pa(pte_newpg[i]) >> PAGE_SHIFT);
 517                         free_p2m_page(pte_newpg[i]);
 518                 }
 519
 520                 vaddr += PMD_SIZE;
 521         }
 522
 523         return lookup_address(addr, &level);
 524 }
 525
 526 /*
 527  * Fully allocate the p2m structure for a given pfn.  We need to check
 528  * that both the top and mid levels are allocated, and make sure the
 529  * parallel mfn tree is kept in sync.  We may race with other cpus, so
 530  * the new pages are installed with cmpxchg; if we lose the race then
 531  * simply free the page we allocated and use the one that's there.
 532  */
 533 static bool alloc_p2m(unsigned long pfn)
 534 {
 535         unsigned topidx;
 536         unsigned long *top_mfn_p, *mid_mfn;
 537         pte_t *ptep, *pte_pg;
 538         unsigned int level;
 539         unsigned long flags;
 540         unsigned long addr = (unsigned long)(xen_p2m_addr + pfn);
 541         unsigned long p2m_pfn;
 542
 543         ptep = lookup_address(addr, &level);
 544         BUG_ON(!ptep || level != PG_LEVEL_4K);
 545         pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
 546
 547         if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) {
 548                 /* PMD level is missing, allocate a new one */
 549                 ptep = alloc_p2m_pmd(addr, pte_pg);
 550                 if (!ptep)
 551                         return false;
 552         }
 553
 554         if (p2m_top_mfn && pfn < MAX_P2M_PFN) {
 555                 topidx = p2m_top_index(pfn);
 556                 top_mfn_p = &p2m_top_mfn[topidx];
 557                 mid_mfn = ACCESS_ONCE(p2m_top_mfn_p[topidx]);
 558
 559                 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
 560
 561                 if (mid_mfn == p2m_mid_missing_mfn) {
 562                         /* Separately check the mid mfn level */
 563                         unsigned long missing_mfn;
 564                         unsigned long mid_mfn_mfn;
 565                         unsigned long old_mfn;
 566
 567                         mid_mfn = alloc_p2m_page();
 568                         if (!mid_mfn)
 569                                 return false;
 570
 571                         p2m_mid_mfn_init(mid_mfn, p2m_missing);
 572
 573                         missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
 574                         mid_mfn_mfn = virt_to_mfn(mid_mfn);
 575                         old_mfn = cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn);
 576                         if (old_mfn != missing_mfn) {
 577                                 free_p2m_page(mid_mfn);
 578                                 mid_mfn = mfn_to_virt(old_mfn);
 579                         } else {
 580                                 p2m_top_mfn_p[topidx] = mid_mfn;
 581                         }
 582                 }
 583         } else {
 584                 mid_mfn = NULL;
 585         }
 586
 587         p2m_pfn = pte_pfn(READ_ONCE(*ptep));
 588         if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) ||
 589             p2m_pfn == PFN_DOWN(__pa(p2m_missing))) {
 590                 /* p2m leaf page is missing */
 591                 unsigned long *p2m;
 592
 593                 p2m = alloc_p2m_page();
 594                 if (!p2m)
 595                         return false;
 596
 597                 if (p2m_pfn == PFN_DOWN(__pa(p2m_missing)))
 598                         p2m_init(p2m);
 599                 else
 600                         p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1));
 601
 602                 spin_lock_irqsave(&p2m_update_lock, flags);
 603
 604                 if (pte_pfn(*ptep) == p2m_pfn) {
 605                         HYPERVISOR_shared_info->arch.p2m_generation++;
 606                         wmb(); /* Tools are synchronizing via p2m_generation. */
 607                         set_pte(ptep,
 608                                 pfn_pte(PFN_DOWN(__pa(p2m)), PAGE_KERNEL));
 609                         wmb(); /* Tools are synchronizing via p2m_generation. */
 610                         HYPERVISOR_shared_info->arch.p2m_generation++;
 611                         if (mid_mfn)
 612                                 mid_mfn[p2m_mid_index(pfn)] = virt_to_mfn(p2m);
 613                         p2m = NULL;
 614                 }
 615
 616                 spin_unlock_irqrestore(&p2m_update_lock, flags);
 617
 618                 if (p2m)
 619                         free_p2m_page(p2m);
 620         }
 621
 622         /* Expanded the p2m? */
 623         if (pfn > xen_p2m_last_pfn) {
 624                 xen_p2m_last_pfn = pfn;
 625                 HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn;
 626         }
 627
 628         return true;
 629 }
 630
 631 unsigned long __init set_phys_range_identity(unsigned long pfn_s,
 632                                       unsigned long pfn_e)
 633 {
 634         unsigned long pfn;
 635
 636         if (unlikely(pfn_s >= xen_p2m_size))
 637                 return 0;
 638
 639         if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
 640                 return pfn_e - pfn_s;
 641
 642         if (pfn_s > pfn_e)
 643                 return 0;
 644
 645         if (pfn_e > xen_p2m_size)
 646                 pfn_e = xen_p2m_size;
 647
 648         for (pfn = pfn_s; pfn < pfn_e; pfn++)
 649                 xen_p2m_addr[pfn] = IDENTITY_FRAME(pfn);
 650
 651         return pfn - pfn_s;
 652 }
 653
 654 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 655 {
 656         pte_t *ptep;
 657         unsigned int level;
 658
 659         /* don't track P2M changes in autotranslate guests */
 660         if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
 661                 return true;
 662
 663         if (unlikely(pfn >= xen_p2m_size)) {
 664                 BUG_ON(mfn != INVALID_P2M_ENTRY);
 665                 return true;
 666         }
 667
 668         /*
 669          * The interface requires atomic updates on p2m elements.
 670          * xen_safe_write_ulong() is using __put_user which does an atomic
 671          * store via asm().
 672          */
 673         if (likely(!xen_safe_write_ulong(xen_p2m_addr + pfn, mfn)))
 674                 return true;
 675
 676         ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
 677         BUG_ON(!ptep || level != PG_LEVEL_4K);
 678
 679         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_missing)))
 680                 return mfn == INVALID_P2M_ENTRY;
 681
 682         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
 683                 return mfn == IDENTITY_FRAME(pfn);
 684
 685         return false;
 686 }
 687
 688 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 689 {
 690         if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
 691                 if (!alloc_p2m(pfn))
 692                         return false;
 693
 694                 return __set_phys_to_machine(pfn, mfn);
 695         }
 696
 697         return true;
 698 }
 699
 700 int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
 701                             struct gnttab_map_grant_ref *kmap_ops,
 702                             struct page **pages, unsigned int count)
 703 {
 704         int i, ret = 0;
 705         pte_t *pte;
 706
 707         if (xen_feature(XENFEAT_auto_translated_physmap))
 708                 return 0;
 709
 710         if (kmap_ops) {
 711                 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
 712                                                 kmap_ops, count);
 713                 if (ret)
 714                         goto out;
 715         }
 716
 717         for (i = 0; i < count; i++) {
 718                 unsigned long mfn, pfn;
 719
 720                 /* Do not add to override if the map failed. */
 721                 if (map_ops[i].status)
 722                         continue;
 723
 724                 if (map_ops[i].flags & GNTMAP_contains_pte) {
 725                         pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
 726                                 (map_ops[i].host_addr & ~PAGE_MASK));
 727                         mfn = pte_mfn(*pte);
 728                 } else {
 729                         mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
 730                 }
 731                 pfn = page_to_pfn(pages[i]);
 732
 733                 WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned");
 734
 735                 if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
 736                         ret = -ENOMEM;
 737                         goto out;
 738                 }
 739         }
 740
 741 out:
 742         return ret;
 743 }
 744 EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping);
 745
 746 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
 747                               struct gnttab_unmap_grant_ref *kunmap_ops,
 748                               struct page **pages, unsigned int count)
 749 {
 750         int i, ret = 0;
 751
 752         if (xen_feature(XENFEAT_auto_translated_physmap))
 753                 return 0;
 754
 755         for (i = 0; i < count; i++) {
 756                 unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i]));
 757                 unsigned long pfn = page_to_pfn(pages[i]);
 758
 759                 if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) {
 760                         ret = -EINVAL;
 761                         goto out;
 762                 }
 763
 764                 set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
 765         }
 766         if (kunmap_ops)
 767                 ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
 768                                                 kunmap_ops, count);
 769 out:
 770         return ret;
 771 }
 772 EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);
 773
 774 #ifdef CONFIG_XEN_DEBUG_FS
 775 #include <linux/debugfs.h>
 776 #include "debugfs.h"
 777 static int p2m_dump_show(struct seq_file *m, void *v)
 778 {
 779         static const char * const type_name[] = {
 780                                 [P2M_TYPE_IDENTITY] = "identity",
 781                                 [P2M_TYPE_MISSING] = "missing",
 782                                 [P2M_TYPE_PFN] = "pfn",
 783                                 [P2M_TYPE_UNKNOWN] = "abnormal"};
 784         unsigned long pfn, first_pfn;
 785         int type, prev_type;
 786
 787         prev_type = xen_p2m_elem_type(0);
 788         first_pfn = 0;
 789
 790         for (pfn = 0; pfn < xen_p2m_size; pfn++) {
 791                 type = xen_p2m_elem_type(pfn);
 792                 if (type != prev_type) {
 793                         seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
 794                                    type_name[prev_type]);
 795                         prev_type = type;
 796                         first_pfn = pfn;
 797                 }
 798         }
 799         seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
 800                    type_name[prev_type]);
 801         return 0;
 802 }
 803
 804 static int p2m_dump_open(struct inode *inode, struct file *filp)
 805 {
 806         return single_open(filp, p2m_dump_show, NULL);
 807 }
 808
 809 static const struct file_operations p2m_dump_fops = {
 810         .open           = p2m_dump_open,
 811         .read           = seq_read,
 812         .llseek         = seq_lseek,
 813         .release        = single_release,
 814 };
 815
 816 static struct dentry *d_mmu_debug;
 817
 818 static int __init xen_p2m_debugfs(void)
 819 {
 820         struct dentry *d_xen = xen_init_debugfs();
 821
 822         if (d_xen == NULL)
 823                 return -ENOMEM;
 824
 825         d_mmu_debug = debugfs_create_dir("mmu", d_xen);
 826
 827         debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops);
 828         return 0;
 829 }
 830 fs_initcall(xen_p2m_debugfs);
 831 #endif /* CONFIG_XEN_DEBUG_FS */