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 if (xen_feature(XENFEAT_auto_translated_physmap)) 343 return; 344 345 BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info); 346 347 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = 348 virt_to_mfn(p2m_top_mfn); 349 HYPERVISOR_shared_info->arch.max_pfn = xen_max_p2m_pfn; 350 } 351 352 /* Set up p2m_top to point to the domain-builder provided p2m pages */ 353 void __init xen_build_dynamic_phys_to_machine(void) 354 { 355 unsigned long *mfn_list; 356 unsigned long max_pfn; 357 unsigned long pfn; 358 359 if (xen_feature(XENFEAT_auto_translated_physmap)) 360 return; 361 362 mfn_list = (unsigned long *)xen_start_info->mfn_list; 363 max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages); 364 xen_max_p2m_pfn = max_pfn; 365 366 p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE); 367 p2m_init(p2m_missing); 368 369 p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE); 370 p2m_mid_init(p2m_mid_missing); 371 372 p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE); 373 p2m_top_init(p2m_top); 374 375 p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE); 376 p2m_init(p2m_identity); 377 378 /* 379 * The domain builder gives us a pre-constructed p2m array in 380 * mfn_list for all the pages initially given to us, so we just 381 * need to graft that into our tree structure. 382 */ 383 for (pfn = 0; pfn < max_pfn; pfn += P2M_PER_PAGE) { 384 unsigned topidx = p2m_top_index(pfn); 385 unsigned mididx = p2m_mid_index(pfn); 386 387 if (p2m_top[topidx] == p2m_mid_missing) { 388 unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE); 389 p2m_mid_init(mid); 390 391 p2m_top[topidx] = mid; 392 } 393 394 /* 395 * As long as the mfn_list has enough entries to completely 396 * fill a p2m page, pointing into the array is ok. But if 397 * not the entries beyond the last pfn will be undefined. 398 */ 399 if (unlikely(pfn + P2M_PER_PAGE > max_pfn)) { 400 unsigned long p2midx; 401 402 p2midx = max_pfn % P2M_PER_PAGE; 403 for ( ; p2midx < P2M_PER_PAGE; p2midx++) 404 mfn_list[pfn + p2midx] = INVALID_P2M_ENTRY; 405 } 406 p2m_top[topidx][mididx] = &mfn_list[pfn]; 407 } 408 409 m2p_override_init(); 410 } 411 #ifdef CONFIG_X86_64 412 #include <linux/bootmem.h> 413 unsigned long __init xen_revector_p2m_tree(void) 414 { 415 unsigned long va_start; 416 unsigned long va_end; 417 unsigned long pfn; 418 unsigned long pfn_free = 0; 419 unsigned long *mfn_list = NULL; 420 unsigned long size; 421 422 va_start = xen_start_info->mfn_list; 423 /*We copy in increments of P2M_PER_PAGE * sizeof(unsigned long), 424 * so make sure it is rounded up to that */ 425 size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long)); 426 va_end = va_start + size; 427 428 /* If we were revectored already, don't do it again. */ 429 if (va_start <= __START_KERNEL_map && va_start >= __PAGE_OFFSET) 430 return 0; 431 432 mfn_list = alloc_bootmem_align(size, PAGE_SIZE); 433 if (!mfn_list) { 434 pr_warn("Could not allocate space for a new P2M tree!\n"); 435 return xen_start_info->mfn_list; 436 } 437 /* Fill it out with INVALID_P2M_ENTRY value */ 438 memset(mfn_list, 0xFF, size); 439 440 for (pfn = 0; pfn < ALIGN(MAX_DOMAIN_PAGES, P2M_PER_PAGE); pfn += P2M_PER_PAGE) { 441 unsigned topidx = p2m_top_index(pfn); 442 unsigned mididx; 443 unsigned long *mid_p; 444 445 if (!p2m_top[topidx]) 446 continue; 447 448 if (p2m_top[topidx] == p2m_mid_missing) 449 continue; 450 451 mididx = p2m_mid_index(pfn); 452 mid_p = p2m_top[topidx][mididx]; 453 if (!mid_p) 454 continue; 455 if ((mid_p == p2m_missing) || (mid_p == p2m_identity)) 456 continue; 457 458 if ((unsigned long)mid_p == INVALID_P2M_ENTRY) 459 continue; 460 461 /* The old va. Rebase it on mfn_list */ 462 if (mid_p >= (unsigned long *)va_start && mid_p <= (unsigned long *)va_end) { 463 unsigned long *new; 464 465 if (pfn_free > (size / sizeof(unsigned long))) { 466 WARN(1, "Only allocated for %ld pages, but we want %ld!\n", 467 size / sizeof(unsigned long), pfn_free); 468 return 0; 469 } 470 new = &mfn_list[pfn_free]; 471 472 copy_page(new, mid_p); 473 p2m_top[topidx][mididx] = &mfn_list[pfn_free]; 474 p2m_top_mfn_p[topidx][mididx] = virt_to_mfn(&mfn_list[pfn_free]); 475 476 pfn_free += P2M_PER_PAGE; 477 478 } 479 /* This should be the leafs allocated for identity from _brk. */ 480 } 481 return (unsigned long)mfn_list; 482 483 } 484 #else 485 unsigned long __init xen_revector_p2m_tree(void) 486 { 487 return 0; 488 } 489 #endif 490 unsigned long get_phys_to_machine(unsigned long pfn) 491 { 492 unsigned topidx, mididx, idx; 493 494 if (unlikely(pfn >= MAX_P2M_PFN)) 495 return INVALID_P2M_ENTRY; 496 497 topidx = p2m_top_index(pfn); 498 mididx = p2m_mid_index(pfn); 499 idx = p2m_index(pfn); 500 501 /* 502 * The INVALID_P2M_ENTRY is filled in both p2m_*identity 503 * and in p2m_*missing, so returning the INVALID_P2M_ENTRY 504 * would be wrong. 505 */ 506 if (p2m_top[topidx][mididx] == p2m_identity) 507 return IDENTITY_FRAME(pfn); 508 509 return p2m_top[topidx][mididx][idx]; 510 } 511 EXPORT_SYMBOL_GPL(get_phys_to_machine); 512 513 static void *alloc_p2m_page(void) 514 { 515 return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT); 516 } 517 518 static void free_p2m_page(void *p) 519 { 520 free_page((unsigned long)p); 521 } 522 523 /* 524 * Fully allocate the p2m structure for a given pfn. We need to check 525 * that both the top and mid levels are allocated, and make sure the 526 * parallel mfn tree is kept in sync. We may race with other cpus, so 527 * the new pages are installed with cmpxchg; if we lose the race then 528 * simply free the page we allocated and use the one that's there. 529 */ 530 static bool alloc_p2m(unsigned long pfn) 531 { 532 unsigned topidx, mididx; 533 unsigned long ***top_p, **mid; 534 unsigned long *top_mfn_p, *mid_mfn; 535 536 topidx = p2m_top_index(pfn); 537 mididx = p2m_mid_index(pfn); 538 539 top_p = &p2m_top[topidx]; 540 mid = *top_p; 541 542 if (mid == p2m_mid_missing) { 543 /* Mid level is missing, allocate a new one */ 544 mid = alloc_p2m_page(); 545 if (!mid) 546 return false; 547 548 p2m_mid_init(mid); 549 550 if (cmpxchg(top_p, p2m_mid_missing, mid) != p2m_mid_missing) 551 free_p2m_page(mid); 552 } 553 554 top_mfn_p = &p2m_top_mfn[topidx]; 555 mid_mfn = p2m_top_mfn_p[topidx]; 556 557 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p); 558 559 if (mid_mfn == p2m_mid_missing_mfn) { 560 /* Separately check the mid mfn level */ 561 unsigned long missing_mfn; 562 unsigned long mid_mfn_mfn; 563 564 mid_mfn = alloc_p2m_page(); 565 if (!mid_mfn) 566 return false; 567 568 p2m_mid_mfn_init(mid_mfn); 569 570 missing_mfn = virt_to_mfn(p2m_mid_missing_mfn); 571 mid_mfn_mfn = virt_to_mfn(mid_mfn); 572 if (cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn) != missing_mfn) 573 free_p2m_page(mid_mfn); 574 else 575 p2m_top_mfn_p[topidx] = mid_mfn; 576 } 577 578 if (p2m_top[topidx][mididx] == p2m_identity || 579 p2m_top[topidx][mididx] == p2m_missing) { 580 /* p2m leaf page is missing */ 581 unsigned long *p2m; 582 unsigned long *p2m_orig = p2m_top[topidx][mididx]; 583 584 p2m = alloc_p2m_page(); 585 if (!p2m) 586 return false; 587 588 p2m_init(p2m); 589 590 if (cmpxchg(&mid[mididx], p2m_orig, p2m) != p2m_orig) 591 free_p2m_page(p2m); 592 else 593 mid_mfn[mididx] = virt_to_mfn(p2m); 594 } 595 596 return true; 597 } 598 599 static bool __init early_alloc_p2m_middle(unsigned long pfn, bool check_boundary) 600 { 601 unsigned topidx, mididx, idx; 602 unsigned long *p2m; 603 unsigned long *mid_mfn_p; 604 605 topidx = p2m_top_index(pfn); 606 mididx = p2m_mid_index(pfn); 607 idx = p2m_index(pfn); 608 609 /* Pfff.. No boundary cross-over, lets get out. */ 610 if (!idx && check_boundary) 611 return false; 612 613 WARN(p2m_top[topidx][mididx] == p2m_identity, 614 "P2M[%d][%d] == IDENTITY, should be MISSING (or alloced)!\n", 615 topidx, mididx); 616 617 /* 618 * Could be done by xen_build_dynamic_phys_to_machine.. 619 */ 620 if (p2m_top[topidx][mididx] != p2m_missing) 621 return false; 622 623 /* Boundary cross-over for the edges: */ 624 p2m = extend_brk(PAGE_SIZE, PAGE_SIZE); 625 626 p2m_init(p2m); 627 628 p2m_top[topidx][mididx] = p2m; 629 630 /* For save/restore we need to MFN of the P2M saved */ 631 632 mid_mfn_p = p2m_top_mfn_p[topidx]; 633 WARN(mid_mfn_p[mididx] != virt_to_mfn(p2m_missing), 634 "P2M_TOP_P[%d][%d] != MFN of p2m_missing!\n", 635 topidx, mididx); 636 mid_mfn_p[mididx] = virt_to_mfn(p2m); 637 638 return true; 639 } 640 641 static bool __init early_alloc_p2m(unsigned long pfn) 642 { 643 unsigned topidx = p2m_top_index(pfn); 644 unsigned long *mid_mfn_p; 645 unsigned long **mid; 646 647 mid = p2m_top[topidx]; 648 mid_mfn_p = p2m_top_mfn_p[topidx]; 649 if (mid == p2m_mid_missing) { 650 mid = extend_brk(PAGE_SIZE, PAGE_SIZE); 651 652 p2m_mid_init(mid); 653 654 p2m_top[topidx] = mid; 655 656 BUG_ON(mid_mfn_p != p2m_mid_missing_mfn); 657 } 658 /* And the save/restore P2M tables.. */ 659 if (mid_mfn_p == p2m_mid_missing_mfn) { 660 mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE); 661 p2m_mid_mfn_init(mid_mfn_p); 662 663 p2m_top_mfn_p[topidx] = mid_mfn_p; 664 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p); 665 /* Note: we don't set mid_mfn_p[midix] here, 666 * look in early_alloc_p2m_middle */ 667 } 668 return true; 669 } 670 671 /* 672 * Skim over the P2M tree looking at pages that are either filled with 673 * INVALID_P2M_ENTRY or with 1:1 PFNs. If found, re-use that page and 674 * replace the P2M leaf with a p2m_missing or p2m_identity. 675 * Stick the old page in the new P2M tree location. 676 */ 677 bool __init early_can_reuse_p2m_middle(unsigned long set_pfn, unsigned long set_mfn) 678 { 679 unsigned topidx; 680 unsigned mididx; 681 unsigned ident_pfns; 682 unsigned inv_pfns; 683 unsigned long *p2m; 684 unsigned long *mid_mfn_p; 685 unsigned idx; 686 unsigned long pfn; 687 688 /* We only look when this entails a P2M middle layer */ 689 if (p2m_index(set_pfn)) 690 return false; 691 692 for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn += P2M_PER_PAGE) { 693 topidx = p2m_top_index(pfn); 694 695 if (!p2m_top[topidx]) 696 continue; 697 698 if (p2m_top[topidx] == p2m_mid_missing) 699 continue; 700 701 mididx = p2m_mid_index(pfn); 702 p2m = p2m_top[topidx][mididx]; 703 if (!p2m) 704 continue; 705 706 if ((p2m == p2m_missing) || (p2m == p2m_identity)) 707 continue; 708 709 if ((unsigned long)p2m == INVALID_P2M_ENTRY) 710 continue; 711 712 ident_pfns = 0; 713 inv_pfns = 0; 714 for (idx = 0; idx < P2M_PER_PAGE; idx++) { 715 /* IDENTITY_PFNs are 1:1 */ 716 if (p2m[idx] == IDENTITY_FRAME(pfn + idx)) 717 ident_pfns++; 718 else if (p2m[idx] == INVALID_P2M_ENTRY) 719 inv_pfns++; 720 else 721 break; 722 } 723 if ((ident_pfns == P2M_PER_PAGE) || (inv_pfns == P2M_PER_PAGE)) 724 goto found; 725 } 726 return false; 727 found: 728 /* Found one, replace old with p2m_identity or p2m_missing */ 729 p2m_top[topidx][mididx] = (ident_pfns ? p2m_identity : p2m_missing); 730 /* And the other for save/restore.. */ 731 mid_mfn_p = p2m_top_mfn_p[topidx]; 732 /* NOTE: Even if it is a p2m_identity it should still be point to 733 * a page filled with INVALID_P2M_ENTRY entries. */ 734 mid_mfn_p[mididx] = virt_to_mfn(p2m_missing); 735 736 /* Reset where we want to stick the old page in. */ 737 topidx = p2m_top_index(set_pfn); 738 mididx = p2m_mid_index(set_pfn); 739 740 /* This shouldn't happen */ 741 if (WARN_ON(p2m_top[topidx] == p2m_mid_missing)) 742 early_alloc_p2m(set_pfn); 743 744 if (WARN_ON(p2m_top[topidx][mididx] != p2m_missing)) 745 return false; 746 747 p2m_init(p2m); 748 p2m_top[topidx][mididx] = p2m; 749 mid_mfn_p = p2m_top_mfn_p[topidx]; 750 mid_mfn_p[mididx] = virt_to_mfn(p2m); 751 752 return true; 753 } 754 bool __init early_set_phys_to_machine(unsigned long pfn, unsigned long mfn) 755 { 756 if (unlikely(!__set_phys_to_machine(pfn, mfn))) { 757 if (!early_alloc_p2m(pfn)) 758 return false; 759 760 if (early_can_reuse_p2m_middle(pfn, mfn)) 761 return __set_phys_to_machine(pfn, mfn); 762 763 if (!early_alloc_p2m_middle(pfn, false /* boundary crossover OK!*/)) 764 return false; 765 766 if (!__set_phys_to_machine(pfn, mfn)) 767 return false; 768 } 769 770 return true; 771 } 772 unsigned long __init set_phys_range_identity(unsigned long pfn_s, 773 unsigned long pfn_e) 774 { 775 unsigned long pfn; 776 777 if (unlikely(pfn_s >= MAX_P2M_PFN || pfn_e >= MAX_P2M_PFN)) 778 return 0; 779 780 if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) 781 return pfn_e - pfn_s; 782 783 if (pfn_s > pfn_e) 784 return 0; 785 786 for (pfn = (pfn_s & ~(P2M_MID_PER_PAGE * P2M_PER_PAGE - 1)); 787 pfn < ALIGN(pfn_e, (P2M_MID_PER_PAGE * P2M_PER_PAGE)); 788 pfn += P2M_MID_PER_PAGE * P2M_PER_PAGE) 789 { 790 WARN_ON(!early_alloc_p2m(pfn)); 791 } 792 793 early_alloc_p2m_middle(pfn_s, true); 794 early_alloc_p2m_middle(pfn_e, true); 795 796 for (pfn = pfn_s; pfn < pfn_e; pfn++) 797 if (!__set_phys_to_machine(pfn, IDENTITY_FRAME(pfn))) 798 break; 799 800 if (!WARN((pfn - pfn_s) != (pfn_e - pfn_s), 801 "Identity mapping failed. We are %ld short of 1-1 mappings!\n", 802 (pfn_e - pfn_s) - (pfn - pfn_s))) 803 printk(KERN_DEBUG "1-1 mapping on %lx->%lx\n", pfn_s, pfn); 804 805 return pfn - pfn_s; 806 } 807 808 /* Try to install p2m mapping; fail if intermediate bits missing */ 809 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn) 810 { 811 unsigned topidx, mididx, idx; 812 813 /* don't track P2M changes in autotranslate guests */ 814 if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) 815 return true; 816 817 if (unlikely(pfn >= MAX_P2M_PFN)) { 818 BUG_ON(mfn != INVALID_P2M_ENTRY); 819 return true; 820 } 821 822 topidx = p2m_top_index(pfn); 823 mididx = p2m_mid_index(pfn); 824 idx = p2m_index(pfn); 825 826 /* For sparse holes were the p2m leaf has real PFN along with 827 * PCI holes, stick in the PFN as the MFN value. 828 */ 829 if (mfn != INVALID_P2M_ENTRY && (mfn & IDENTITY_FRAME_BIT)) { 830 if (p2m_top[topidx][mididx] == p2m_identity) 831 return true; 832 833 /* Swap over from MISSING to IDENTITY if needed. */ 834 if (p2m_top[topidx][mididx] == p2m_missing) { 835 WARN_ON(cmpxchg(&p2m_top[topidx][mididx], p2m_missing, 836 p2m_identity) != p2m_missing); 837 return true; 838 } 839 } 840 841 if (p2m_top[topidx][mididx] == p2m_missing) 842 return mfn == INVALID_P2M_ENTRY; 843 844 p2m_top[topidx][mididx][idx] = mfn; 845 846 return true; 847 } 848 849 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn) 850 { 851 if (unlikely(!__set_phys_to_machine(pfn, mfn))) { 852 if (!alloc_p2m(pfn)) 853 return false; 854 855 if (!__set_phys_to_machine(pfn, mfn)) 856 return false; 857 } 858 859 return true; 860 } 861 862 #define M2P_OVERRIDE_HASH_SHIFT 10 863 #define M2P_OVERRIDE_HASH (1 << M2P_OVERRIDE_HASH_SHIFT) 864 865 static RESERVE_BRK_ARRAY(struct list_head, m2p_overrides, M2P_OVERRIDE_HASH); 866 static DEFINE_SPINLOCK(m2p_override_lock); 867 868 static void __init m2p_override_init(void) 869 { 870 unsigned i; 871 872 m2p_overrides = extend_brk(sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH, 873 sizeof(unsigned long)); 874 875 for (i = 0; i < M2P_OVERRIDE_HASH; i++) 876 INIT_LIST_HEAD(&m2p_overrides[i]); 877 } 878 879 static unsigned long mfn_hash(unsigned long mfn) 880 { 881 return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT); 882 } 883 884 /* Add an MFN override for a particular page */ 885 int m2p_add_override(unsigned long mfn, struct page *page, 886 struct gnttab_map_grant_ref *kmap_op) 887 { 888 unsigned long flags; 889 unsigned long pfn; 890 unsigned long uninitialized_var(address); 891 unsigned level; 892 pte_t *ptep = NULL; 893 894 pfn = page_to_pfn(page); 895 if (!PageHighMem(page)) { 896 address = (unsigned long)__va(pfn << PAGE_SHIFT); 897 ptep = lookup_address(address, &level); 898 if (WARN(ptep == NULL || level != PG_LEVEL_4K, 899 "m2p_add_override: pfn %lx not mapped", pfn)) 900 return -EINVAL; 901 } 902 WARN_ON(PagePrivate(page)); 903 SetPagePrivate(page); 904 set_page_private(page, mfn); 905 page->index = pfn_to_mfn(pfn); 906 907 if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) 908 return -ENOMEM; 909 910 if (kmap_op != NULL) { 911 if (!PageHighMem(page)) { 912 struct multicall_space mcs = 913 xen_mc_entry(sizeof(*kmap_op)); 914 915 MULTI_grant_table_op(mcs.mc, 916 GNTTABOP_map_grant_ref, kmap_op, 1); 917 918 xen_mc_issue(PARAVIRT_LAZY_MMU); 919 } 920 } 921 spin_lock_irqsave(&m2p_override_lock, flags); 922 list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]); 923 spin_unlock_irqrestore(&m2p_override_lock, flags); 924 925 /* p2m(m2p(mfn)) == mfn: the mfn is already present somewhere in 926 * this domain. Set the FOREIGN_FRAME_BIT in the p2m for the other 927 * pfn so that the following mfn_to_pfn(mfn) calls will return the 928 * pfn from the m2p_override (the backend pfn) instead. 929 * We need to do this because the pages shared by the frontend 930 * (xen-blkfront) can be already locked (lock_page, called by 931 * do_read_cache_page); when the userspace backend tries to use them 932 * with direct_IO, mfn_to_pfn returns the pfn of the frontend, so 933 * do_blockdev_direct_IO is going to try to lock the same pages 934 * again resulting in a deadlock. 935 * As a side effect get_user_pages_fast might not be safe on the 936 * frontend pages while they are being shared with the backend, 937 * because mfn_to_pfn (that ends up being called by GUPF) will 938 * return the backend pfn rather than the frontend pfn. */ 939 pfn = mfn_to_pfn_no_overrides(mfn); 940 if (get_phys_to_machine(pfn) == mfn) 941 set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)); 942 943 return 0; 944 } 945 EXPORT_SYMBOL_GPL(m2p_add_override); 946 int m2p_remove_override(struct page *page, 947 struct gnttab_map_grant_ref *kmap_op) 948 { 949 unsigned long flags; 950 unsigned long mfn; 951 unsigned long pfn; 952 unsigned long uninitialized_var(address); 953 unsigned level; 954 pte_t *ptep = NULL; 955 956 pfn = page_to_pfn(page); 957 mfn = get_phys_to_machine(pfn); 958 if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) 959 return -EINVAL; 960 961 if (!PageHighMem(page)) { 962 address = (unsigned long)__va(pfn << PAGE_SHIFT); 963 ptep = lookup_address(address, &level); 964 965 if (WARN(ptep == NULL || level != PG_LEVEL_4K, 966 "m2p_remove_override: pfn %lx not mapped", pfn)) 967 return -EINVAL; 968 } 969 970 spin_lock_irqsave(&m2p_override_lock, flags); 971 list_del(&page->lru); 972 spin_unlock_irqrestore(&m2p_override_lock, flags); 973 WARN_ON(!PagePrivate(page)); 974 ClearPagePrivate(page); 975 976 set_phys_to_machine(pfn, page->index); 977 if (kmap_op != NULL) { 978 if (!PageHighMem(page)) { 979 struct multicall_space mcs; 980 struct gnttab_unmap_and_replace *unmap_op; 981 struct page *scratch_page = get_balloon_scratch_page(); 982 unsigned long scratch_page_address = (unsigned long) 983 __va(page_to_pfn(scratch_page) << PAGE_SHIFT); 984 985 /* 986 * It might be that we queued all the m2p grant table 987 * hypercalls in a multicall, then m2p_remove_override 988 * get called before the multicall has actually been 989 * issued. In this case handle is going to -1 because 990 * it hasn't been modified yet. 991 */ 992 if (kmap_op->handle == -1) 993 xen_mc_flush(); 994 /* 995 * Now if kmap_op->handle is negative it means that the 996 * hypercall actually returned an error. 997 */ 998 if (kmap_op->handle == GNTST_general_error) { 999 printk(KERN_WARNING "m2p_remove_override: " 1000 "pfn %lx mfn %lx, failed to modify kernel mappings", 1001 pfn, mfn); 1002 put_balloon_scratch_page(); 1003 return -1; 1004 } 1005 1006 xen_mc_batch(); 1007 1008 mcs = __xen_mc_entry( 1009 sizeof(struct gnttab_unmap_and_replace)); 1010 unmap_op = mcs.args; 1011 unmap_op->host_addr = kmap_op->host_addr; 1012 unmap_op->new_addr = scratch_page_address; 1013 unmap_op->handle = kmap_op->handle; 1014 1015 MULTI_grant_table_op(mcs.mc, 1016 GNTTABOP_unmap_and_replace, unmap_op, 1); 1017 1018 mcs = __xen_mc_entry(0); 1019 MULTI_update_va_mapping(mcs.mc, scratch_page_address, 1020 pfn_pte(page_to_pfn(scratch_page), 1021 PAGE_KERNEL_RO), 0); 1022 1023 xen_mc_issue(PARAVIRT_LAZY_MMU); 1024 1025 kmap_op->host_addr = 0; 1026 put_balloon_scratch_page(); 1027 } 1028 } 1029 1030 /* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present 1031 * somewhere in this domain, even before being added to the 1032 * m2p_override (see comment above in m2p_add_override). 1033 * If there are no other entries in the m2p_override corresponding 1034 * to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for 1035 * the original pfn (the one shared by the frontend): the backend 1036 * cannot do any IO on this page anymore because it has been 1037 * unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of 1038 * the original pfn causes mfn_to_pfn(mfn) to return the frontend 1039 * pfn again. */ 1040 mfn &= ~FOREIGN_FRAME_BIT; 1041 pfn = mfn_to_pfn_no_overrides(mfn); 1042 if (get_phys_to_machine(pfn) == FOREIGN_FRAME(mfn) && 1043 m2p_find_override(mfn) == NULL) 1044 set_phys_to_machine(pfn, mfn); 1045 1046 return 0; 1047 } 1048 EXPORT_SYMBOL_GPL(m2p_remove_override); 1049 1050 struct page *m2p_find_override(unsigned long mfn) 1051 { 1052 unsigned long flags; 1053 struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)]; 1054 struct page *p, *ret; 1055 1056 ret = NULL; 1057 1058 spin_lock_irqsave(&m2p_override_lock, flags); 1059 1060 list_for_each_entry(p, bucket, lru) { 1061 if (page_private(p) == mfn) { 1062 ret = p; 1063 break; 1064 } 1065 } 1066 1067 spin_unlock_irqrestore(&m2p_override_lock, flags); 1068 1069 return ret; 1070 } 1071 1072 unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn) 1073 { 1074 struct page *p = m2p_find_override(mfn); 1075 unsigned long ret = pfn; 1076 1077 if (p) 1078 ret = page_to_pfn(p); 1079 1080 return ret; 1081 } 1082 EXPORT_SYMBOL_GPL(m2p_find_override_pfn); 1083 1084 #ifdef CONFIG_XEN_DEBUG_FS 1085 #include <linux/debugfs.h> 1086 #include "debugfs.h" 1087 static int p2m_dump_show(struct seq_file *m, void *v) 1088 { 1089 static const char * const level_name[] = { "top", "middle", 1090 "entry", "abnormal", "error"}; 1091 #define TYPE_IDENTITY 0 1092 #define TYPE_MISSING 1 1093 #define TYPE_PFN 2 1094 #define TYPE_UNKNOWN 3 1095 static const char * const type_name[] = { 1096 [TYPE_IDENTITY] = "identity", 1097 [TYPE_MISSING] = "missing", 1098 [TYPE_PFN] = "pfn", 1099 [TYPE_UNKNOWN] = "abnormal"}; 1100 unsigned long pfn, prev_pfn_type = 0, prev_pfn_level = 0; 1101 unsigned int uninitialized_var(prev_level); 1102 unsigned int uninitialized_var(prev_type); 1103 1104 if (!p2m_top) 1105 return 0; 1106 1107 for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn++) { 1108 unsigned topidx = p2m_top_index(pfn); 1109 unsigned mididx = p2m_mid_index(pfn); 1110 unsigned idx = p2m_index(pfn); 1111 unsigned lvl, type; 1112 1113 lvl = 4; 1114 type = TYPE_UNKNOWN; 1115 if (p2m_top[topidx] == p2m_mid_missing) { 1116 lvl = 0; type = TYPE_MISSING; 1117 } else if (p2m_top[topidx] == NULL) { 1118 lvl = 0; type = TYPE_UNKNOWN; 1119 } else if (p2m_top[topidx][mididx] == NULL) { 1120 lvl = 1; type = TYPE_UNKNOWN; 1121 } else if (p2m_top[topidx][mididx] == p2m_identity) { 1122 lvl = 1; type = TYPE_IDENTITY; 1123 } else if (p2m_top[topidx][mididx] == p2m_missing) { 1124 lvl = 1; type = TYPE_MISSING; 1125 } else if (p2m_top[topidx][mididx][idx] == 0) { 1126 lvl = 2; type = TYPE_UNKNOWN; 1127 } else if (p2m_top[topidx][mididx][idx] == IDENTITY_FRAME(pfn)) { 1128 lvl = 2; type = TYPE_IDENTITY; 1129 } else if (p2m_top[topidx][mididx][idx] == INVALID_P2M_ENTRY) { 1130 lvl = 2; type = TYPE_MISSING; 1131 } else if (p2m_top[topidx][mididx][idx] == pfn) { 1132 lvl = 2; type = TYPE_PFN; 1133 } else if (p2m_top[topidx][mididx][idx] != pfn) { 1134 lvl = 2; type = TYPE_PFN; 1135 } 1136 if (pfn == 0) { 1137 prev_level = lvl; 1138 prev_type = type; 1139 } 1140 if (pfn == MAX_DOMAIN_PAGES-1) { 1141 lvl = 3; 1142 type = TYPE_UNKNOWN; 1143 } 1144 if (prev_type != type) { 1145 seq_printf(m, " [0x%lx->0x%lx] %s\n", 1146 prev_pfn_type, pfn, type_name[prev_type]); 1147 prev_pfn_type = pfn; 1148 prev_type = type; 1149 } 1150 if (prev_level != lvl) { 1151 seq_printf(m, " [0x%lx->0x%lx] level %s\n", 1152 prev_pfn_level, pfn, level_name[prev_level]); 1153 prev_pfn_level = pfn; 1154 prev_level = lvl; 1155 } 1156 } 1157 return 0; 1158 #undef TYPE_IDENTITY 1159 #undef TYPE_MISSING 1160 #undef TYPE_PFN 1161 #undef TYPE_UNKNOWN 1162 } 1163 1164 static int p2m_dump_open(struct inode *inode, struct file *filp) 1165 { 1166 return single_open(filp, p2m_dump_show, NULL); 1167 } 1168 1169 static const struct file_operations p2m_dump_fops = { 1170 .open = p2m_dump_open, 1171 .read = seq_read, 1172 .llseek = seq_lseek, 1173 .release = single_release, 1174 }; 1175 1176 static struct dentry *d_mmu_debug; 1177 1178 static int __init xen_p2m_debugfs(void) 1179 { 1180 struct dentry *d_xen = xen_init_debugfs(); 1181 1182 if (d_xen == NULL) 1183 return -ENOMEM; 1184 1185 d_mmu_debug = debugfs_create_dir("mmu", d_xen); 1186 1187 debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops); 1188 return 0; 1189 } 1190 fs_initcall(xen_p2m_debugfs); 1191 #endif /* CONFIG_XEN_DEBUG_FS */ 1192