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 p2m table is logically a flat array, but we implement it as a
   7  * three-level tree to allow the address space to be sparse.
   8  *
   9  *                               Xen
  10  *                                |
  11  *     p2m_top              p2m_top_mfn
  12  *       /  \                   /   \
  13  * p2m_mid p2m_mid      p2m_mid_mfn p2m_mid_mfn
  14  *    / \      / \         /           /
  15  *  p2m p2m p2m p2m p2m p2m p2m ...
  16  *
  17  * The p2m_mid_mfn pages are mapped by p2m_top_mfn_p.
  18  *
  19  * The p2m_top and p2m_top_mfn levels are limited to 1 page, so the
  20  * maximum representable pseudo-physical address space is:
  21  *  P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE pages
  22  *
  23  * P2M_PER_PAGE depends on the architecture, as a mfn is always
  24  * unsigned long (8 bytes on 64-bit, 4 bytes on 32), leading to
  25  * 512 and 1024 entries respectively.
  26  *
  27  * In short, these structures contain the Machine Frame Number (MFN) of the PFN.
  28  *
  29  * However not all entries are filled with MFNs. Specifically for all other
  30  * leaf entries, or for the top  root, or middle one, for which there is a void
  31  * entry, we assume it is  "missing". So (for example)
  32  *  pfn_to_mfn(0x90909090)=INVALID_P2M_ENTRY.
  33  *
  34  * We also have the possibility of setting 1-1 mappings on certain regions, so
  35  * that:
  36  *  pfn_to_mfn(0xc0000)=0xc0000
  37  *
  38  * The benefit of this is, that we can assume for non-RAM regions (think
  39  * PCI BARs, or ACPI spaces), we can create mappings easily b/c we
  40  * get the PFN value to match the MFN.
  41  *
  42  * For this to work efficiently we have one new page p2m_identity and
  43  * allocate (via reserved_brk) any other pages we need to cover the sides
  44  * (1GB or 4MB boundary violations). All entries in p2m_identity are set to
  45  * INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
  46  * no other fancy value).
  47  *
  48  * On lookup we spot that the entry points to p2m_identity and return the
  49  * identity value instead of dereferencing and returning INVALID_P2M_ENTRY.
  50  * If the entry points to an allocated page, we just proceed as before and
  51  * return the PFN.  If the PFN has IDENTITY_FRAME_BIT set we unmask that in
  52  * appropriate functions (pfn_to_mfn).
  53  *
  54  * The reason for having the IDENTITY_FRAME_BIT instead of just returning the
  55  * PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
  56  * non-identity pfn. To protect ourselves against we elect to set (and get) the
  57  * IDENTITY_FRAME_BIT on all identity mapped PFNs.
  58  *
  59  * This simplistic diagram is used to explain the more subtle piece of code.
  60  * There is also a digram of the P2M at the end that can help.
  61  * Imagine your E820 looking as so:
  62  *
  63  *                    1GB                                           2GB
  64  * /-------------------+---------\/----\         /----------\    /---+-----\
  65  * | System RAM        | Sys RAM ||ACPI|         | reserved |    | Sys RAM |
  66  * \-------------------+---------/\----/         \----------/    \---+-----/
  67  *                               ^- 1029MB                       ^- 2001MB
  68  *
  69  * [1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100),
  70  *  2048MB = 524288 (0x80000)]
  71  *
  72  * And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
  73  * is actually not present (would have to kick the balloon driver to put it in).
  74  *
  75  * When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
  76  * Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
  77  * of the PFN and the end PFN (263424 and 512256 respectively). The first step
  78  * is to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
  79  * covers 512^2 of page estate (1GB) and in case the start or end PFN is not
  80  * aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn
  81  * to end pfn.  We reserve_brk top leaf pages if they are missing (means they
  82  * point to p2m_mid_missing).
  83  *
  84  * With the E820 example above, 263424 is not 1GB aligned so we allocate a
  85  * reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
  86  * Each entry in the allocate page is "missing" (points to p2m_missing).
  87  *
  88  * Next stage is to determine if we need to do a more granular boundary check
  89  * on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
  90  * We check if the start pfn and end pfn violate that boundary check, and if
  91  * so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
  92  * granularity of setting which PFNs are missing and which ones are identity.
  93  * In our example 263424 and 512256 both fail the check so we reserve_brk two
  94  * pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing"
  95  * values) and assign them to p2m[1][2] and p2m[1][488] respectively.
  96  *
  97  * At this point we would at minimum reserve_brk one page, but could be up to
  98  * three. Each call to set_phys_range_identity has at maximum a three page
  99  * cost. If we were to query the P2M at this stage, all those entries from
 100  * start PFN through end PFN (so 1029MB -> 2001MB) would return
 101  * INVALID_P2M_ENTRY ("missing").
 102  *
 103  * The next step is to walk from the start pfn to the end pfn setting
 104  * the IDENTITY_FRAME_BIT on each PFN. This is done in set_phys_range_identity.
 105  * If we find that the middle leaf is pointing to p2m_missing we can swap it
 106  * over to p2m_identity - this way covering 4MB (or 2MB) PFN space.  At this
 107  * point we do not need to worry about boundary aligment (so no need to
 108  * reserve_brk a middle page, figure out which PFNs are "missing" and which
 109  * ones are identity), as that has been done earlier.  If we find that the
 110  * middle leaf is not occupied by p2m_identity or p2m_missing, we dereference
 111  * that page (which covers 512 PFNs) and set the appropriate PFN with
 112  * IDENTITY_FRAME_BIT. In our example 263424 and 512256 end up there, and we
 113  * set from p2m[1][2][256->511] and p2m[1][488][0->256] with
 114  * IDENTITY_FRAME_BIT set.
 115  *
 116  * All other regions that are void (or not filled) either point to p2m_missing
 117  * (considered missing) or have the default value of INVALID_P2M_ENTRY (also
 118  * considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
 119  * contain the INVALID_P2M_ENTRY value and are considered "missing."
 120  *
 121  * This is what the p2m ends up looking (for the E820 above) with this
 122  * fabulous drawing:
 123  *
 124  *    p2m         /--------------\
 125  *  /-----\       | &mfn_list[0],|                           /-----------------\
 126  *  |  0  |------>| &mfn_list[1],|    /---------------\      | ~0, ~0, ..      |
 127  *  |-----|       |  ..., ~0, ~0 |    | ~0, ~0, [x]---+----->| IDENTITY [@256] |
 128  *  |  1  |---\   \--------------/    | [p2m_identity]+\     | IDENTITY [@257] |
 129  *  |-----|    \                      | [p2m_identity]+\\    | ....            |
 130  *  |  2  |--\  \-------------------->|  ...          | \\   \----------------/
 131  *  |-----|   \                       \---------------/  \\
 132  *  |  3  |\   \                                          \\  p2m_identity
 133  *  |-----| \   \-------------------->/---------------\   /-----------------\
 134  *  | ..  +->+                        | [p2m_identity]+-->| ~0, ~0, ~0, ... |
 135  *  \-----/ /                         | [p2m_identity]+-->| ..., ~0         |
 136  *         / /---------------\        | ....          |   \-----------------/
 137  *        /  | IDENTITY[@0]  |      /-+-[x], ~0, ~0.. |
 138  *       /   | IDENTITY[@256]|<----/  \---------------/
 139  *      /    | ~0, ~0, ....  |
 140  *     |     \---------------/
 141  *     |
 142  *   p2m_mid_missing           p2m_missing
 143  * /-----------------\     /------------\
 144  * | [p2m_missing]   +---->| ~0, ~0, ~0 |
 145  * | [p2m_missing]   +---->| ..., ~0    |
 146  * \-----------------/     \------------/
 147  *
 148  * where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
 149  */
 150
 151 #include <linux/init.h>
 152 #include <linux/module.h>
 153 #include <linux/list.h>
 154 #include <linux/hash.h>
 155 #include <linux/sched.h>
 156 #include <linux/seq_file.h>
 157
 158 #include <asm/cache.h>
 159 #include <asm/setup.h>
 160
 161 #include <asm/xen/page.h>
 162 #include <asm/xen/hypercall.h>
 163 #include <asm/xen/hypervisor.h>
 164 #include <xen/balloon.h>
 165 #include <xen/grant_table.h>
 166
 167 #include "multicalls.h"
 168 #include "xen-ops.h"
 169
 170 static void __init m2p_override_init(void);
 171
 172 unsigned long xen_max_p2m_pfn __read_mostly;
 173
 174 #define P2M_PER_PAGE            (PAGE_SIZE / sizeof(unsigned long))
 175 #define P2M_MID_PER_PAGE        (PAGE_SIZE / sizeof(unsigned long *))
 176 #define P2M_TOP_PER_PAGE        (PAGE_SIZE / sizeof(unsigned long **))
 177
 178 #define MAX_P2M_PFN             (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE)
 179
 180 /* Placeholders for holes in the address space */
 181 static RESERVE_BRK_ARRAY(unsigned long, p2m_missing, P2M_PER_PAGE);
 182 static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_missing, P2M_MID_PER_PAGE);
 183 static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_missing_mfn, P2M_MID_PER_PAGE);
 184
 185 static RESERVE_BRK_ARRAY(unsigned long **, p2m_top, P2M_TOP_PER_PAGE);
 186 static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, P2M_TOP_PER_PAGE);
 187 static RESERVE_BRK_ARRAY(unsigned long *, p2m_top_mfn_p, P2M_TOP_PER_PAGE);
 188
 189 static RESERVE_BRK_ARRAY(unsigned long, p2m_identity, P2M_PER_PAGE);
 190
 191 RESERVE_BRK(p2m_mid, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
 192 RESERVE_BRK(p2m_mid_mfn, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
 193
 194 /* We might hit two boundary violations at the start and end, at max each
 195  * boundary violation will require three middle nodes. */
 196 RESERVE_BRK(p2m_mid_identity, PAGE_SIZE * 2 * 3);
 197
 198 /* When we populate back during bootup, the amount of pages can vary. The
 199  * max we have is seen is 395979, but that does not mean it can't be more.
 200  * Some machines can have 3GB I/O holes even. With early_can_reuse_p2m_middle
 201  * it can re-use Xen provided mfn_list array, so we only need to allocate at
 202  * most three P2M top nodes. */
 203 RESERVE_BRK(p2m_populated, PAGE_SIZE * 3);
 204
 205 static inline unsigned p2m_top_index(unsigned long pfn)
 206 {
 207         BUG_ON(pfn >= MAX_P2M_PFN);
 208         return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
 209 }
 210
 211 static inline unsigned p2m_mid_index(unsigned long pfn)
 212 {
 213         return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
 214 }
 215
 216 static inline unsigned p2m_index(unsigned long pfn)
 217 {
 218         return pfn % P2M_PER_PAGE;
 219 }
 220
 221 static void p2m_top_init(unsigned long ***top)
 222 {
 223         unsigned i;
 224
 225         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
 226                 top[i] = p2m_mid_missing;
 227 }
 228
 229 static void p2m_top_mfn_init(unsigned long *top)
 230 {
 231         unsigned i;
 232
 233         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
 234                 top[i] = virt_to_mfn(p2m_mid_missing_mfn);
 235 }
 236
 237 static void p2m_top_mfn_p_init(unsigned long **top)
 238 {
 239         unsigned i;
 240
 241         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
 242                 top[i] = p2m_mid_missing_mfn;
 243 }
 244
 245 static void p2m_mid_init(unsigned long **mid)
 246 {
 247         unsigned i;
 248
 249         for (i = 0; i < P2M_MID_PER_PAGE; i++)
 250                 mid[i] = p2m_missing;
 251 }
 252
 253 static void p2m_mid_mfn_init(unsigned long *mid)
 254 {
 255         unsigned i;
 256
 257         for (i = 0; i < P2M_MID_PER_PAGE; i++)
 258                 mid[i] = virt_to_mfn(p2m_missing);
 259 }
 260
 261 static void p2m_init(unsigned long *p2m)
 262 {
 263         unsigned i;
 264
 265         for (i = 0; i < P2M_MID_PER_PAGE; i++)
 266                 p2m[i] = INVALID_P2M_ENTRY;
 267 }
 268
 269 /*
 270  * Build the parallel p2m_top_mfn and p2m_mid_mfn structures
 271  *
 272  * This is called both at boot time, and after resuming from suspend:
 273  * - At boot time we're called very early, and must use extend_brk()
 274  *   to allocate memory.
 275  *
 276  * - After resume we're called from within stop_machine, but the mfn
 277  *   tree should alreay be completely allocated.
 278  */
 279 void __ref xen_build_mfn_list_list(void)
 280 {
 281         unsigned long pfn;
 282
 283         if (xen_feature(XENFEAT_auto_translated_physmap))
 284                 return;
 285
 286         /* Pre-initialize p2m_top_mfn to be completely missing */
 287         if (p2m_top_mfn == NULL) {
 288                 p2m_mid_missing_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
 289                 p2m_mid_mfn_init(p2m_mid_missing_mfn);
 290
 291                 p2m_top_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
 292                 p2m_top_mfn_p_init(p2m_top_mfn_p);
 293
 294                 p2m_top_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
 295                 p2m_top_mfn_init(p2m_top_mfn);
 296         } else {
 297                 /* Reinitialise, mfn's all change after migration */
 298                 p2m_mid_mfn_init(p2m_mid_missing_mfn);
 299         }
 300
 301         for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += P2M_PER_PAGE) {
 302                 unsigned topidx = p2m_top_index(pfn);
 303                 unsigned mididx = p2m_mid_index(pfn);
 304                 unsigned long **mid;
 305                 unsigned long *mid_mfn_p;
 306
 307                 mid = p2m_top[topidx];
 308                 mid_mfn_p = p2m_top_mfn_p[topidx];
 309
 310                 /* Don't bother allocating any mfn mid levels if
 311                  * they're just missing, just update the stored mfn,
 312                  * since all could have changed over a migrate.
 313                  */
 314                 if (mid == p2m_mid_missing) {
 315                         BUG_ON(mididx);
 316                         BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
 317                         p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
 318                         pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
 319                         continue;
 320                 }
 321
 322                 if (mid_mfn_p == p2m_mid_missing_mfn) {
 323                         /*
 324                          * XXX boot-time only!  We should never find
 325                          * missing parts of the mfn tree after
 326                          * runtime.  extend_brk() will BUG if we call
 327                          * it too late.
 328                          */
 329                         mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
 330                         p2m_mid_mfn_init(mid_mfn_p);
 331
 332                         p2m_top_mfn_p[topidx] = mid_mfn_p;
 333                 }
 334
 335                 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
 336                 mid_mfn_p[mididx] = virt_to_mfn(mid[mididx]);
 337         }
 338 }
 339
 340 void xen_setup_mfn_list_list(void)
 341 {
 342         BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
 343
 344         HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
 345                 virt_to_mfn(p2m_top_mfn);
 346         HYPERVISOR_shared_info->arch.max_pfn = xen_max_p2m_pfn;
 347 }
 348
 349 /* Set up p2m_top to point to the domain-builder provided p2m pages */
 350 void __init xen_build_dynamic_phys_to_machine(void)
 351 {
 352         unsigned long *mfn_list;
 353         unsigned long max_pfn;
 354         unsigned long pfn;
 355
 356          if (xen_feature(XENFEAT_auto_translated_physmap))
 357                 return;
 358
 359         mfn_list = (unsigned long *)xen_start_info->mfn_list;
 360         max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages);
 361         xen_max_p2m_pfn = max_pfn;
 362
 363         p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
 364         p2m_init(p2m_missing);
 365
 366         p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
 367         p2m_mid_init(p2m_mid_missing);
 368
 369         p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE);
 370         p2m_top_init(p2m_top);
 371
 372         p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE);
 373         p2m_init(p2m_identity);
 374
 375         /*
 376          * The domain builder gives us a pre-constructed p2m array in
 377          * mfn_list for all the pages initially given to us, so we just
 378          * need to graft that into our tree structure.
 379          */
 380         for (pfn = 0; pfn < max_pfn; pfn += P2M_PER_PAGE) {
 381                 unsigned topidx = p2m_top_index(pfn);
 382                 unsigned mididx = p2m_mid_index(pfn);
 383
 384                 if (p2m_top[topidx] == p2m_mid_missing) {
 385                         unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
 386                         p2m_mid_init(mid);
 387
 388                         p2m_top[topidx] = mid;
 389                 }
 390
 391                 /*
 392                  * As long as the mfn_list has enough entries to completely
 393                  * fill a p2m page, pointing into the array is ok. But if
 394                  * not the entries beyond the last pfn will be undefined.
 395                  */
 396                 if (unlikely(pfn + P2M_PER_PAGE > max_pfn)) {
 397                         unsigned long p2midx;
 398
 399                         p2midx = max_pfn % P2M_PER_PAGE;
 400                         for ( ; p2midx < P2M_PER_PAGE; p2midx++)
 401                                 mfn_list[pfn + p2midx] = INVALID_P2M_ENTRY;
 402                 }
 403                 p2m_top[topidx][mididx] = &mfn_list[pfn];
 404         }
 405
 406         m2p_override_init();
 407 }
 408 #ifdef CONFIG_X86_64
 409 #include <linux/bootmem.h>
 410 unsigned long __init xen_revector_p2m_tree(void)
 411 {
 412         unsigned long va_start;
 413         unsigned long va_end;
 414         unsigned long pfn;
 415         unsigned long pfn_free = 0;
 416         unsigned long *mfn_list = NULL;
 417         unsigned long size;
 418
 419         va_start = xen_start_info->mfn_list;
 420         /*We copy in increments of P2M_PER_PAGE * sizeof(unsigned long),
 421          * so make sure it is rounded up to that */
 422         size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long));
 423         va_end = va_start + size;
 424
 425         /* If we were revectored already, don't do it again. */
 426         if (va_start <= __START_KERNEL_map && va_start >= __PAGE_OFFSET)
 427                 return 0;
 428
 429         mfn_list = alloc_bootmem_align(size, PAGE_SIZE);
 430         if (!mfn_list) {
 431                 pr_warn("Could not allocate space for a new P2M tree!\n");
 432                 return xen_start_info->mfn_list;
 433         }
 434         /* Fill it out with INVALID_P2M_ENTRY value */
 435         memset(mfn_list, 0xFF, size);
 436
 437         for (pfn = 0; pfn < ALIGN(MAX_DOMAIN_PAGES, P2M_PER_PAGE); pfn += P2M_PER_PAGE) {
 438                 unsigned topidx = p2m_top_index(pfn);
 439                 unsigned mididx;
 440                 unsigned long *mid_p;
 441
 442                 if (!p2m_top[topidx])
 443                         continue;
 444
 445                 if (p2m_top[topidx] == p2m_mid_missing)
 446                         continue;
 447
 448                 mididx = p2m_mid_index(pfn);
 449                 mid_p = p2m_top[topidx][mididx];
 450                 if (!mid_p)
 451                         continue;
 452                 if ((mid_p == p2m_missing) || (mid_p == p2m_identity))
 453                         continue;
 454
 455                 if ((unsigned long)mid_p == INVALID_P2M_ENTRY)
 456                         continue;
 457
 458                 /* The old va. Rebase it on mfn_list */
 459                 if (mid_p >= (unsigned long *)va_start && mid_p <= (unsigned long *)va_end) {
 460                         unsigned long *new;
 461
 462                         if (pfn_free  > (size / sizeof(unsigned long))) {
 463                                 WARN(1, "Only allocated for %ld pages, but we want %ld!\n",
 464                                      size / sizeof(unsigned long), pfn_free);
 465                                 return 0;
 466                         }
 467                         new = &mfn_list[pfn_free];
 468
 469                         copy_page(new, mid_p);
 470                         p2m_top[topidx][mididx] = &mfn_list[pfn_free];
 471                         p2m_top_mfn_p[topidx][mididx] = virt_to_mfn(&mfn_list[pfn_free]);
 472
 473                         pfn_free += P2M_PER_PAGE;
 474
 475                 }
 476                 /* This should be the leafs allocated for identity from _brk. */
 477         }
 478         return (unsigned long)mfn_list;
 479
 480 }
 481 #else
 482 unsigned long __init xen_revector_p2m_tree(void)
 483 {
 484         return 0;
 485 }
 486 #endif
 487 unsigned long get_phys_to_machine(unsigned long pfn)
 488 {
 489         unsigned topidx, mididx, idx;
 490
 491         if (unlikely(pfn >= MAX_P2M_PFN))
 492                 return INVALID_P2M_ENTRY;
 493
 494         topidx = p2m_top_index(pfn);
 495         mididx = p2m_mid_index(pfn);
 496         idx = p2m_index(pfn);
 497
 498         /*
 499          * The INVALID_P2M_ENTRY is filled in both p2m_*identity
 500          * and in p2m_*missing, so returning the INVALID_P2M_ENTRY
 501          * would be wrong.
 502          */
 503         if (p2m_top[topidx][mididx] == p2m_identity)
 504                 return IDENTITY_FRAME(pfn);
 505
 506         return p2m_top[topidx][mididx][idx];
 507 }
 508 EXPORT_SYMBOL_GPL(get_phys_to_machine);
 509
 510 static void *alloc_p2m_page(void)
 511 {
 512         return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT);
 513 }
 514
 515 static void free_p2m_page(void *p)
 516 {
 517         free_page((unsigned long)p);
 518 }
 519
 520 /*
 521  * Fully allocate the p2m structure for a given pfn.  We need to check
 522  * that both the top and mid levels are allocated, and make sure the
 523  * parallel mfn tree is kept in sync.  We may race with other cpus, so
 524  * the new pages are installed with cmpxchg; if we lose the race then
 525  * simply free the page we allocated and use the one that's there.
 526  */
 527 static bool alloc_p2m(unsigned long pfn)
 528 {
 529         unsigned topidx, mididx;
 530         unsigned long ***top_p, **mid;
 531         unsigned long *top_mfn_p, *mid_mfn;
 532
 533         topidx = p2m_top_index(pfn);
 534         mididx = p2m_mid_index(pfn);
 535
 536         top_p = &p2m_top[topidx];
 537         mid = *top_p;
 538
 539         if (mid == p2m_mid_missing) {
 540                 /* Mid level is missing, allocate a new one */
 541                 mid = alloc_p2m_page();
 542                 if (!mid)
 543                         return false;
 544
 545                 p2m_mid_init(mid);
 546
 547                 if (cmpxchg(top_p, p2m_mid_missing, mid) != p2m_mid_missing)
 548                         free_p2m_page(mid);
 549         }
 550
 551         top_mfn_p = &p2m_top_mfn[topidx];
 552         mid_mfn = p2m_top_mfn_p[topidx];
 553
 554         BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
 555
 556         if (mid_mfn == p2m_mid_missing_mfn) {
 557                 /* Separately check the mid mfn level */
 558                 unsigned long missing_mfn;
 559                 unsigned long mid_mfn_mfn;
 560
 561                 mid_mfn = alloc_p2m_page();
 562                 if (!mid_mfn)
 563                         return false;
 564
 565                 p2m_mid_mfn_init(mid_mfn);
 566
 567                 missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
 568                 mid_mfn_mfn = virt_to_mfn(mid_mfn);
 569                 if (cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn) != missing_mfn)
 570                         free_p2m_page(mid_mfn);
 571                 else
 572                         p2m_top_mfn_p[topidx] = mid_mfn;
 573         }
 574
 575         if (p2m_top[topidx][mididx] == p2m_identity ||
 576             p2m_top[topidx][mididx] == p2m_missing) {
 577                 /* p2m leaf page is missing */
 578                 unsigned long *p2m;
 579                 unsigned long *p2m_orig = p2m_top[topidx][mididx];
 580
 581                 p2m = alloc_p2m_page();
 582                 if (!p2m)
 583                         return false;
 584
 585                 p2m_init(p2m);
 586
 587                 if (cmpxchg(&mid[mididx], p2m_orig, p2m) != p2m_orig)
 588                         free_p2m_page(p2m);
 589                 else
 590                         mid_mfn[mididx] = virt_to_mfn(p2m);
 591         }
 592
 593         return true;
 594 }
 595
 596 static bool __init early_alloc_p2m_middle(unsigned long pfn, bool check_boundary)
 597 {
 598         unsigned topidx, mididx, idx;
 599         unsigned long *p2m;
 600         unsigned long *mid_mfn_p;
 601
 602         topidx = p2m_top_index(pfn);
 603         mididx = p2m_mid_index(pfn);
 604         idx = p2m_index(pfn);
 605
 606         /* Pfff.. No boundary cross-over, lets get out. */
 607         if (!idx && check_boundary)
 608                 return false;
 609
 610         WARN(p2m_top[topidx][mididx] == p2m_identity,
 611                 "P2M[%d][%d] == IDENTITY, should be MISSING (or alloced)!\n",
 612                 topidx, mididx);
 613
 614         /*
 615          * Could be done by xen_build_dynamic_phys_to_machine..
 616          */
 617         if (p2m_top[topidx][mididx] != p2m_missing)
 618                 return false;
 619
 620         /* Boundary cross-over for the edges: */
 621         p2m = extend_brk(PAGE_SIZE, PAGE_SIZE);
 622
 623         p2m_init(p2m);
 624
 625         p2m_top[topidx][mididx] = p2m;
 626
 627         /* For save/restore we need to MFN of the P2M saved */
 628
 629         mid_mfn_p = p2m_top_mfn_p[topidx];
 630         WARN(mid_mfn_p[mididx] != virt_to_mfn(p2m_missing),
 631                 "P2M_TOP_P[%d][%d] != MFN of p2m_missing!\n",
 632                 topidx, mididx);
 633         mid_mfn_p[mididx] = virt_to_mfn(p2m);
 634
 635         return true;
 636 }
 637
 638 static bool __init early_alloc_p2m(unsigned long pfn)
 639 {
 640         unsigned topidx = p2m_top_index(pfn);
 641         unsigned long *mid_mfn_p;
 642         unsigned long **mid;
 643
 644         mid = p2m_top[topidx];
 645         mid_mfn_p = p2m_top_mfn_p[topidx];
 646         if (mid == p2m_mid_missing) {
 647                 mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
 648
 649                 p2m_mid_init(mid);
 650
 651                 p2m_top[topidx] = mid;
 652
 653                 BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
 654         }
 655         /* And the save/restore P2M tables.. */
 656         if (mid_mfn_p == p2m_mid_missing_mfn) {
 657                 mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
 658                 p2m_mid_mfn_init(mid_mfn_p);
 659
 660                 p2m_top_mfn_p[topidx] = mid_mfn_p;
 661                 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
 662                 /* Note: we don't set mid_mfn_p[midix] here,
 663                  * look in early_alloc_p2m_middle */
 664         }
 665         return true;
 666 }
 667
 668 /*
 669  * Skim over the P2M tree looking at pages that are either filled with
 670  * INVALID_P2M_ENTRY or with 1:1 PFNs. If found, re-use that page and
 671  * replace the P2M leaf with a p2m_missing or p2m_identity.
 672  * Stick the old page in the new P2M tree location.
 673  */
 674 bool __init early_can_reuse_p2m_middle(unsigned long set_pfn, unsigned long set_mfn)
 675 {
 676         unsigned topidx;
 677         unsigned mididx;
 678         unsigned ident_pfns;
 679         unsigned inv_pfns;
 680         unsigned long *p2m;
 681         unsigned long *mid_mfn_p;
 682         unsigned idx;
 683         unsigned long pfn;
 684
 685         /* We only look when this entails a P2M middle layer */
 686         if (p2m_index(set_pfn))
 687                 return false;
 688
 689         for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn += P2M_PER_PAGE) {
 690                 topidx = p2m_top_index(pfn);
 691
 692                 if (!p2m_top[topidx])
 693                         continue;
 694
 695                 if (p2m_top[topidx] == p2m_mid_missing)
 696                         continue;
 697
 698                 mididx = p2m_mid_index(pfn);
 699                 p2m = p2m_top[topidx][mididx];
 700                 if (!p2m)
 701                         continue;
 702
 703                 if ((p2m == p2m_missing) || (p2m == p2m_identity))
 704                         continue;
 705
 706                 if ((unsigned long)p2m == INVALID_P2M_ENTRY)
 707                         continue;
 708
 709                 ident_pfns = 0;
 710                 inv_pfns = 0;
 711                 for (idx = 0; idx < P2M_PER_PAGE; idx++) {
 712                         /* IDENTITY_PFNs are 1:1 */
 713                         if (p2m[idx] == IDENTITY_FRAME(pfn + idx))
 714                                 ident_pfns++;
 715                         else if (p2m[idx] == INVALID_P2M_ENTRY)
 716                                 inv_pfns++;
 717                         else
 718                                 break;
 719                 }
 720                 if ((ident_pfns == P2M_PER_PAGE) || (inv_pfns == P2M_PER_PAGE))
 721                         goto found;
 722         }
 723         return false;
 724 found:
 725         /* Found one, replace old with p2m_identity or p2m_missing */
 726         p2m_top[topidx][mididx] = (ident_pfns ? p2m_identity : p2m_missing);
 727         /* And the other for save/restore.. */
 728         mid_mfn_p = p2m_top_mfn_p[topidx];
 729         /* NOTE: Even if it is a p2m_identity it should still be point to
 730          * a page filled with INVALID_P2M_ENTRY entries. */
 731         mid_mfn_p[mididx] = virt_to_mfn(p2m_missing);
 732
 733         /* Reset where we want to stick the old page in. */
 734         topidx = p2m_top_index(set_pfn);
 735         mididx = p2m_mid_index(set_pfn);
 736
 737         /* This shouldn't happen */
 738         if (WARN_ON(p2m_top[topidx] == p2m_mid_missing))
 739                 early_alloc_p2m(set_pfn);
 740
 741         if (WARN_ON(p2m_top[topidx][mididx] != p2m_missing))
 742                 return false;
 743
 744         p2m_init(p2m);
 745         p2m_top[topidx][mididx] = p2m;
 746         mid_mfn_p = p2m_top_mfn_p[topidx];
 747         mid_mfn_p[mididx] = virt_to_mfn(p2m);
 748
 749         return true;
 750 }
 751 bool __init early_set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 752 {
 753         if (unlikely(!__set_phys_to_machine(pfn, mfn)))  {
 754                 if (!early_alloc_p2m(pfn))
 755                         return false;
 756
 757                 if (early_can_reuse_p2m_middle(pfn, mfn))
 758                         return __set_phys_to_machine(pfn, mfn);
 759
 760                 if (!early_alloc_p2m_middle(pfn, false /* boundary crossover OK!*/))
 761                         return false;
 762
 763                 if (!__set_phys_to_machine(pfn, mfn))
 764                         return false;
 765         }
 766
 767         return true;
 768 }
 769 unsigned long __init set_phys_range_identity(unsigned long pfn_s,
 770                                       unsigned long pfn_e)
 771 {
 772         unsigned long pfn;
 773
 774         if (unlikely(pfn_s >= MAX_P2M_PFN || pfn_e >= MAX_P2M_PFN))
 775                 return 0;
 776
 777         if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
 778                 return pfn_e - pfn_s;
 779
 780         if (pfn_s > pfn_e)
 781                 return 0;
 782
 783         for (pfn = (pfn_s & ~(P2M_MID_PER_PAGE * P2M_PER_PAGE - 1));
 784                 pfn < ALIGN(pfn_e, (P2M_MID_PER_PAGE * P2M_PER_PAGE));
 785                 pfn += P2M_MID_PER_PAGE * P2M_PER_PAGE)
 786         {
 787                 WARN_ON(!early_alloc_p2m(pfn));
 788         }
 789
 790         early_alloc_p2m_middle(pfn_s, true);
 791         early_alloc_p2m_middle(pfn_e, true);
 792
 793         for (pfn = pfn_s; pfn < pfn_e; pfn++)
 794                 if (!__set_phys_to_machine(pfn, IDENTITY_FRAME(pfn)))
 795                         break;
 796
 797         if (!WARN((pfn - pfn_s) != (pfn_e - pfn_s),
 798                 "Identity mapping failed. We are %ld short of 1-1 mappings!\n",
 799                 (pfn_e - pfn_s) - (pfn - pfn_s)))
 800                 printk(KERN_DEBUG "1-1 mapping on %lx->%lx\n", pfn_s, pfn);
 801
 802         return pfn - pfn_s;
 803 }
 804
 805 /* Try to install p2m mapping; fail if intermediate bits missing */
 806 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 807 {
 808         unsigned topidx, mididx, idx;
 809
 810         /* don't track P2M changes in autotranslate guests */
 811         if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
 812                 return true;
 813
 814         if (unlikely(pfn >= MAX_P2M_PFN)) {
 815                 BUG_ON(mfn != INVALID_P2M_ENTRY);
 816                 return true;
 817         }
 818
 819         topidx = p2m_top_index(pfn);
 820         mididx = p2m_mid_index(pfn);
 821         idx = p2m_index(pfn);
 822
 823         /* For sparse holes were the p2m leaf has real PFN along with
 824          * PCI holes, stick in the PFN as the MFN value.
 825          */
 826         if (mfn != INVALID_P2M_ENTRY && (mfn & IDENTITY_FRAME_BIT)) {
 827                 if (p2m_top[topidx][mididx] == p2m_identity)
 828                         return true;
 829
 830                 /* Swap over from MISSING to IDENTITY if needed. */
 831                 if (p2m_top[topidx][mididx] == p2m_missing) {
 832                         WARN_ON(cmpxchg(&p2m_top[topidx][mididx], p2m_missing,
 833                                 p2m_identity) != p2m_missing);
 834                         return true;
 835                 }
 836         }
 837
 838         if (p2m_top[topidx][mididx] == p2m_missing)
 839                 return mfn == INVALID_P2M_ENTRY;
 840
 841         p2m_top[topidx][mididx][idx] = mfn;
 842
 843         return true;
 844 }
 845
 846 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 847 {
 848         if (unlikely(!__set_phys_to_machine(pfn, mfn)))  {
 849                 if (!alloc_p2m(pfn))
 850                         return false;
 851
 852                 if (!__set_phys_to_machine(pfn, mfn))
 853                         return false;
 854         }
 855
 856         return true;
 857 }
 858
 859 #define M2P_OVERRIDE_HASH_SHIFT 10
 860 #define M2P_OVERRIDE_HASH       (1 << M2P_OVERRIDE_HASH_SHIFT)
 861
 862 static RESERVE_BRK_ARRAY(struct list_head, m2p_overrides, M2P_OVERRIDE_HASH);
 863 static DEFINE_SPINLOCK(m2p_override_lock);
 864
 865 static void __init m2p_override_init(void)
 866 {
 867         unsigned i;
 868
 869         m2p_overrides = extend_brk(sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH,
 870                                    sizeof(unsigned long));
 871
 872         for (i = 0; i < M2P_OVERRIDE_HASH; i++)
 873                 INIT_LIST_HEAD(&m2p_overrides[i]);
 874 }
 875
 876 static unsigned long mfn_hash(unsigned long mfn)
 877 {
 878         return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT);
 879 }
 880
 881 /* Add an MFN override for a particular page */
 882 int m2p_add_override(unsigned long mfn, struct page *page,
 883                 struct gnttab_map_grant_ref *kmap_op)
 884 {
 885         unsigned long flags;
 886         unsigned long pfn;
 887         unsigned long uninitialized_var(address);
 888         unsigned level;
 889         pte_t *ptep = NULL;
 890
 891         pfn = page_to_pfn(page);
 892         if (!PageHighMem(page)) {
 893                 address = (unsigned long)__va(pfn << PAGE_SHIFT);
 894                 ptep = lookup_address(address, &level);
 895                 if (WARN(ptep == NULL || level != PG_LEVEL_4K,
 896                                         "m2p_add_override: pfn %lx not mapped", pfn))
 897                         return -EINVAL;
 898         }
 899         WARN_ON(PagePrivate(page));
 900         SetPagePrivate(page);
 901         set_page_private(page, mfn);
 902         page->index = pfn_to_mfn(pfn);
 903
 904         if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))
 905                 return -ENOMEM;
 906
 907         if (kmap_op != NULL) {
 908                 if (!PageHighMem(page)) {
 909                         struct multicall_space mcs =
 910                                 xen_mc_entry(sizeof(*kmap_op));
 911
 912                         MULTI_grant_table_op(mcs.mc,
 913                                         GNTTABOP_map_grant_ref, kmap_op, 1);
 914
 915                         xen_mc_issue(PARAVIRT_LAZY_MMU);
 916                 }
 917         }
 918         spin_lock_irqsave(&m2p_override_lock, flags);
 919         list_add(&page->lru,  &m2p_overrides[mfn_hash(mfn)]);
 920         spin_unlock_irqrestore(&m2p_override_lock, flags);
 921
 922         /* p2m(m2p(mfn)) == mfn: the mfn is already present somewhere in
 923          * this domain. Set the FOREIGN_FRAME_BIT in the p2m for the other
 924          * pfn so that the following mfn_to_pfn(mfn) calls will return the
 925          * pfn from the m2p_override (the backend pfn) instead.
 926          * We need to do this because the pages shared by the frontend
 927          * (xen-blkfront) can be already locked (lock_page, called by
 928          * do_read_cache_page); when the userspace backend tries to use them
 929          * with direct_IO, mfn_to_pfn returns the pfn of the frontend, so
 930          * do_blockdev_direct_IO is going to try to lock the same pages
 931          * again resulting in a deadlock.
 932          * As a side effect get_user_pages_fast might not be safe on the
 933          * frontend pages while they are being shared with the backend,
 934          * because mfn_to_pfn (that ends up being called by GUPF) will
 935          * return the backend pfn rather than the frontend pfn. */
 936         pfn = mfn_to_pfn_no_overrides(mfn);
 937         if (get_phys_to_machine(pfn) == mfn)
 938                 set_phys_to_machine(pfn, FOREIGN_FRAME(mfn));
 939
 940         return 0;
 941 }
 942 EXPORT_SYMBOL_GPL(m2p_add_override);
 943 int m2p_remove_override(struct page *page,
 944                 struct gnttab_map_grant_ref *kmap_op)
 945 {
 946         unsigned long flags;
 947         unsigned long mfn;
 948         unsigned long pfn;
 949         unsigned long uninitialized_var(address);
 950         unsigned level;
 951         pte_t *ptep = NULL;
 952
 953         pfn = page_to_pfn(page);
 954         mfn = get_phys_to_machine(pfn);
 955         if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
 956                 return -EINVAL;
 957
 958         if (!PageHighMem(page)) {
 959                 address = (unsigned long)__va(pfn << PAGE_SHIFT);
 960                 ptep = lookup_address(address, &level);
 961
 962                 if (WARN(ptep == NULL || level != PG_LEVEL_4K,
 963                                         "m2p_remove_override: pfn %lx not mapped", pfn))
 964                         return -EINVAL;
 965         }
 966
 967         spin_lock_irqsave(&m2p_override_lock, flags);
 968         list_del(&page->lru);
 969         spin_unlock_irqrestore(&m2p_override_lock, flags);
 970         WARN_ON(!PagePrivate(page));
 971         ClearPagePrivate(page);
 972
 973         set_phys_to_machine(pfn, page->index);
 974         if (kmap_op != NULL) {
 975                 if (!PageHighMem(page)) {
 976                         struct multicall_space mcs;
 977                         struct gnttab_unmap_and_replace *unmap_op;
 978                         struct page *scratch_page = get_balloon_scratch_page();
 979                         unsigned long scratch_page_address = (unsigned long)
 980                                 __va(page_to_pfn(scratch_page) << PAGE_SHIFT);
 981
 982                         /*
 983                          * It might be that we queued all the m2p grant table
 984                          * hypercalls in a multicall, then m2p_remove_override
 985                          * get called before the multicall has actually been
 986                          * issued. In this case handle is going to -1 because
 987                          * it hasn't been modified yet.
 988                          */
 989                         if (kmap_op->handle == -1)
 990                                 xen_mc_flush();
 991                         /*
 992                          * Now if kmap_op->handle is negative it means that the
 993                          * hypercall actually returned an error.
 994                          */
 995                         if (kmap_op->handle == GNTST_general_error) {
 996                                 printk(KERN_WARNING "m2p_remove_override: "
 997                                                 "pfn %lx mfn %lx, failed to modify kernel mappings",
 998                                                 pfn, mfn);
 999                                 put_balloon_scratch_page();
1000                                 return -1;
1001                         }
1002
1003                         xen_mc_batch();
1004
1005                         mcs = __xen_mc_entry(
1006                                         sizeof(struct gnttab_unmap_and_replace));
1007                         unmap_op = mcs.args;
1008                         unmap_op->host_addr = kmap_op->host_addr;
1009                         unmap_op->new_addr = scratch_page_address;
1010                         unmap_op->handle = kmap_op->handle;
1011
1012                         MULTI_grant_table_op(mcs.mc,
1013                                         GNTTABOP_unmap_and_replace, unmap_op, 1);
1014
1015                         mcs = __xen_mc_entry(0);
1016                         MULTI_update_va_mapping(mcs.mc, scratch_page_address,
1017                                         pfn_pte(page_to_pfn(scratch_page),
1018                                         PAGE_KERNEL_RO), 0);
1019
1020                         xen_mc_issue(PARAVIRT_LAZY_MMU);
1021
1022                         kmap_op->host_addr = 0;
1023                         put_balloon_scratch_page();
1024                 }
1025         }
1026
1027         /* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present
1028          * somewhere in this domain, even before being added to the
1029          * m2p_override (see comment above in m2p_add_override).
1030          * If there are no other entries in the m2p_override corresponding
1031          * to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for
1032          * the original pfn (the one shared by the frontend): the backend
1033          * cannot do any IO on this page anymore because it has been
1034          * unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of
1035          * the original pfn causes mfn_to_pfn(mfn) to return the frontend
1036          * pfn again. */
1037         mfn &= ~FOREIGN_FRAME_BIT;
1038         pfn = mfn_to_pfn_no_overrides(mfn);
1039         if (get_phys_to_machine(pfn) == FOREIGN_FRAME(mfn) &&
1040                         m2p_find_override(mfn) == NULL)
1041                 set_phys_to_machine(pfn, mfn);
1042
1043         return 0;
1044 }
1045 EXPORT_SYMBOL_GPL(m2p_remove_override);
1046
1047 struct page *m2p_find_override(unsigned long mfn)
1048 {
1049         unsigned long flags;
1050         struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)];
1051         struct page *p, *ret;
1052
1053         ret = NULL;
1054
1055         spin_lock_irqsave(&m2p_override_lock, flags);
1056
1057         list_for_each_entry(p, bucket, lru) {
1058                 if (page_private(p) == mfn) {
1059                         ret = p;
1060                         break;
1061                 }
1062         }
1063
1064         spin_unlock_irqrestore(&m2p_override_lock, flags);
1065
1066         return ret;
1067 }
1068
1069 unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn)
1070 {
1071         struct page *p = m2p_find_override(mfn);
1072         unsigned long ret = pfn;
1073
1074         if (p)
1075                 ret = page_to_pfn(p);
1076
1077         return ret;
1078 }
1079 EXPORT_SYMBOL_GPL(m2p_find_override_pfn);
1080
1081 #ifdef CONFIG_XEN_DEBUG_FS
1082 #include <linux/debugfs.h>
1083 #include "debugfs.h"
1084 static int p2m_dump_show(struct seq_file *m, void *v)
1085 {
1086         static const char * const level_name[] = { "top", "middle",
1087                                                 "entry", "abnormal", "error"};
1088 #define TYPE_IDENTITY 0
1089 #define TYPE_MISSING 1
1090 #define TYPE_PFN 2
1091 #define TYPE_UNKNOWN 3
1092         static const char * const type_name[] = {
1093                                 [TYPE_IDENTITY] = "identity",
1094                                 [TYPE_MISSING] = "missing",
1095                                 [TYPE_PFN] = "pfn",
1096                                 [TYPE_UNKNOWN] = "abnormal"};
1097         unsigned long pfn, prev_pfn_type = 0, prev_pfn_level = 0;
1098         unsigned int uninitialized_var(prev_level);
1099         unsigned int uninitialized_var(prev_type);
1100
1101         if (!p2m_top)
1102                 return 0;
1103
1104         for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn++) {
1105                 unsigned topidx = p2m_top_index(pfn);
1106                 unsigned mididx = p2m_mid_index(pfn);
1107                 unsigned idx = p2m_index(pfn);
1108                 unsigned lvl, type;
1109
1110                 lvl = 4;
1111                 type = TYPE_UNKNOWN;
1112                 if (p2m_top[topidx] == p2m_mid_missing) {
1113                         lvl = 0; type = TYPE_MISSING;
1114                 } else if (p2m_top[topidx] == NULL) {
1115                         lvl = 0; type = TYPE_UNKNOWN;
1116                 } else if (p2m_top[topidx][mididx] == NULL) {
1117                         lvl = 1; type = TYPE_UNKNOWN;
1118                 } else if (p2m_top[topidx][mididx] == p2m_identity) {
1119                         lvl = 1; type = TYPE_IDENTITY;
1120                 } else if (p2m_top[topidx][mididx] == p2m_missing) {
1121                         lvl = 1; type = TYPE_MISSING;
1122                 } else if (p2m_top[topidx][mididx][idx] == 0) {
1123                         lvl = 2; type = TYPE_UNKNOWN;
1124                 } else if (p2m_top[topidx][mididx][idx] == IDENTITY_FRAME(pfn)) {
1125                         lvl = 2; type = TYPE_IDENTITY;
1126                 } else if (p2m_top[topidx][mididx][idx] == INVALID_P2M_ENTRY) {
1127                         lvl = 2; type = TYPE_MISSING;
1128                 } else if (p2m_top[topidx][mididx][idx] == pfn) {
1129                         lvl = 2; type = TYPE_PFN;
1130                 } else if (p2m_top[topidx][mididx][idx] != pfn) {
1131                         lvl = 2; type = TYPE_PFN;
1132                 }
1133                 if (pfn == 0) {
1134                         prev_level = lvl;
1135                         prev_type = type;
1136                 }
1137                 if (pfn == MAX_DOMAIN_PAGES-1) {
1138                         lvl = 3;
1139                         type = TYPE_UNKNOWN;
1140                 }
1141                 if (prev_type != type) {
1142                         seq_printf(m, " [0x%lx->0x%lx] %s\n",
1143                                 prev_pfn_type, pfn, type_name[prev_type]);
1144                         prev_pfn_type = pfn;
1145                         prev_type = type;
1146                 }
1147                 if (prev_level != lvl) {
1148                         seq_printf(m, " [0x%lx->0x%lx] level %s\n",
1149                                 prev_pfn_level, pfn, level_name[prev_level]);
1150                         prev_pfn_level = pfn;
1151                         prev_level = lvl;
1152                 }
1153         }
1154         return 0;
1155 #undef TYPE_IDENTITY
1156 #undef TYPE_MISSING
1157 #undef TYPE_PFN
1158 #undef TYPE_UNKNOWN
1159 }
1160
1161 static int p2m_dump_open(struct inode *inode, struct file *filp)
1162 {
1163         return single_open(filp, p2m_dump_show, NULL);
1164 }
1165
1166 static const struct file_operations p2m_dump_fops = {
1167         .open           = p2m_dump_open,
1168         .read           = seq_read,
1169         .llseek         = seq_lseek,
1170         .release        = single_release,
1171 };
1172
1173 static struct dentry *d_mmu_debug;
1174
1175 static int __init xen_p2m_debugfs(void)
1176 {
1177         struct dentry *d_xen = xen_init_debugfs();
1178
1179         if (d_xen == NULL)
1180                 return -ENOMEM;
1181
1182         d_mmu_debug = debugfs_create_dir("mmu", d_xen);
1183
1184         debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops);
1185         return 0;
1186 }
1187 fs_initcall(xen_p2m_debugfs);
1188 #endif /* CONFIG_XEN_DEBUG_FS */