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 because 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 4GB 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 reserve_brk new middle and leaf pages as 81 * required to split any existing p2m_mid_missing middle pages. 82 * 83 * With the E820 example above, 263424 is not 1GB aligned so we allocate a 84 * reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000. 85 * Each entry in the allocate page is "missing" (points to p2m_missing). 86 * 87 * Next stage is to determine if we need to do a more granular boundary check 88 * on the 4MB (or 2MB depending on architecture) off the start and end pfn's. 89 * We check if the start pfn and end pfn violate that boundary check, and if 90 * so reserve_brk a (p2m[x][y]) leaf page. This way we have a much finer 91 * granularity of setting which PFNs are missing and which ones are identity. 92 * In our example 263424 and 512256 both fail the check so we reserve_brk two 93 * pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" 94 * values) and assign them to p2m[1][2] and p2m[1][488] respectively. 95 * 96 * At this point we would at minimum reserve_brk one page, but could be up to 97 * three. Each call to set_phys_range_identity has at maximum a three page 98 * cost. If we were to query the P2M at this stage, all those entries from 99 * start PFN through end PFN (so 1029MB -> 2001MB) would return 100 * INVALID_P2M_ENTRY ("missing"). 101 * 102 * The next step is to walk from the start pfn to the end pfn setting 103 * the IDENTITY_FRAME_BIT on each PFN. This is done in set_phys_range_identity. 104 * If we find that the middle entry is pointing to p2m_missing we can swap it 105 * over to p2m_identity - this way covering 4MB (or 2MB) PFN space (and 106 * similarly swapping p2m_mid_missing for p2m_mid_identity for larger regions). 107 * At this 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 * Finally, the region beyond the end of of the E820 (4 GB in this example) 122 * is set to be identity (in case there are MMIO regions placed here). 123 * 124 * This is what the p2m ends up looking (for the E820 above) with this 125 * fabulous drawing: 126 * 127 * p2m /--------------\ 128 * /-----\ | &mfn_list[0],| /-----------------\ 129 * | 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. | 130 * |-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] | 131 * | 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] | 132 * |-----| \ | [p2m_identity]+\\ | .... | 133 * | 2 |--\ \-------------------->| ... | \\ \----------------/ 134 * |-----| \ \---------------/ \\ 135 * | 3 |-\ \ \\ p2m_identity [1] 136 * |-----| \ \-------------------->/---------------\ /-----------------\ 137 * | .. |\ | | [p2m_identity]+-->| ~0, ~0, ~0, ... | 138 * \-----/ | | | [p2m_identity]+-->| ..., ~0 | 139 * | | | .... | \-----------------/ 140 * | | +-[x], ~0, ~0.. +\ 141 * | | \---------------/ \ 142 * | | \-> /---------------\ 143 * | V p2m_mid_missing p2m_missing | IDENTITY[@0] | 144 * | /-----------------\ /------------\ | IDENTITY[@256]| 145 * | | [p2m_missing] +---->| ~0, ~0, ...| | ~0, ~0, .... | 146 * | | [p2m_missing] +---->| ..., ~0 | \---------------/ 147 * | | ... | \------------/ 148 * | \-----------------/ 149 * | 150 * | p2m_mid_identity 151 * | /-----------------\ 152 * \-->| [p2m_identity] +---->[1] 153 * | [p2m_identity] +---->[1] 154 * | ... | 155 * \-----------------/ 156 * 157 * where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT) 158 */ 159 160 #include <linux/init.h> 161 #include <linux/module.h> 162 #include <linux/list.h> 163 #include <linux/hash.h> 164 #include <linux/sched.h> 165 #include <linux/seq_file.h> 166 167 #include <asm/cache.h> 168 #include <asm/setup.h> 169 170 #include <asm/xen/page.h> 171 #include <asm/xen/hypercall.h> 172 #include <asm/xen/hypervisor.h> 173 #include <xen/balloon.h> 174 #include <xen/grant_table.h> 175 176 #include "multicalls.h" 177 #include "xen-ops.h" 178 179 static void __init m2p_override_init(void); 180 181 unsigned long xen_max_p2m_pfn __read_mostly; 182 183 #define P2M_PER_PAGE (PAGE_SIZE / sizeof(unsigned long)) 184 #define P2M_MID_PER_PAGE (PAGE_SIZE / sizeof(unsigned long *)) 185 #define P2M_TOP_PER_PAGE (PAGE_SIZE / sizeof(unsigned long **)) 186 187 #define MAX_P2M_PFN (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE) 188 189 /* Placeholders for holes in the address space */ 190 static RESERVE_BRK_ARRAY(unsigned long, p2m_missing, P2M_PER_PAGE); 191 static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_missing, P2M_MID_PER_PAGE); 192 static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_missing_mfn, P2M_MID_PER_PAGE); 193 194 static RESERVE_BRK_ARRAY(unsigned long **, p2m_top, P2M_TOP_PER_PAGE); 195 static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, P2M_TOP_PER_PAGE); 196 static RESERVE_BRK_ARRAY(unsigned long *, p2m_top_mfn_p, P2M_TOP_PER_PAGE); 197 198 static RESERVE_BRK_ARRAY(unsigned long, p2m_identity, P2M_PER_PAGE); 199 static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_identity, P2M_MID_PER_PAGE); 200 static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_identity_mfn, P2M_MID_PER_PAGE); 201 202 RESERVE_BRK(p2m_mid, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE))); 203 RESERVE_BRK(p2m_mid_mfn, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE))); 204 205 /* We might hit two boundary violations at the start and end, at max each 206 * boundary violation will require three middle nodes. */ 207 RESERVE_BRK(p2m_mid_extra, PAGE_SIZE * 2 * 3); 208 209 /* When we populate back during bootup, the amount of pages can vary. The 210 * max we have is seen is 395979, but that does not mean it can't be more. 211 * Some machines can have 3GB I/O holes even. With early_can_reuse_p2m_middle 212 * it can re-use Xen provided mfn_list array, so we only need to allocate at 213 * most three P2M top nodes. */ 214 RESERVE_BRK(p2m_populated, PAGE_SIZE * 3); 215 216 static inline unsigned p2m_top_index(unsigned long pfn) 217 { 218 BUG_ON(pfn >= MAX_P2M_PFN); 219 return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE); 220 } 221 222 static inline unsigned p2m_mid_index(unsigned long pfn) 223 { 224 return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE; 225 } 226 227 static inline unsigned p2m_index(unsigned long pfn) 228 { 229 return pfn % P2M_PER_PAGE; 230 } 231 232 static void p2m_top_init(unsigned long ***top) 233 { 234 unsigned i; 235 236 for (i = 0; i < P2M_TOP_PER_PAGE; i++) 237 top[i] = p2m_mid_missing; 238 } 239 240 static void p2m_top_mfn_init(unsigned long *top) 241 { 242 unsigned i; 243 244 for (i = 0; i < P2M_TOP_PER_PAGE; i++) 245 top[i] = virt_to_mfn(p2m_mid_missing_mfn); 246 } 247 248 static void p2m_top_mfn_p_init(unsigned long **top) 249 { 250 unsigned i; 251 252 for (i = 0; i < P2M_TOP_PER_PAGE; i++) 253 top[i] = p2m_mid_missing_mfn; 254 } 255 256 static void p2m_mid_init(unsigned long **mid, unsigned long *leaf) 257 { 258 unsigned i; 259 260 for (i = 0; i < P2M_MID_PER_PAGE; i++) 261 mid[i] = leaf; 262 } 263 264 static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf) 265 { 266 unsigned i; 267 268 for (i = 0; i < P2M_MID_PER_PAGE; i++) 269 mid[i] = virt_to_mfn(leaf); 270 } 271 272 static void p2m_init(unsigned long *p2m) 273 { 274 unsigned i; 275 276 for (i = 0; i < P2M_MID_PER_PAGE; i++) 277 p2m[i] = INVALID_P2M_ENTRY; 278 } 279 280 /* 281 * Build the parallel p2m_top_mfn and p2m_mid_mfn structures 282 * 283 * This is called both at boot time, and after resuming from suspend: 284 * - At boot time we're called very early, and must use extend_brk() 285 * to allocate memory. 286 * 287 * - After resume we're called from within stop_machine, but the mfn 288 * tree should alreay be completely allocated. 289 */ 290 void __ref xen_build_mfn_list_list(void) 291 { 292 unsigned long pfn; 293 294 if (xen_feature(XENFEAT_auto_translated_physmap)) 295 return; 296 297 /* Pre-initialize p2m_top_mfn to be completely missing */ 298 if (p2m_top_mfn == NULL) { 299 p2m_mid_missing_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE); 300 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing); 301 p2m_mid_identity_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE); 302 p2m_mid_mfn_init(p2m_mid_identity_mfn, p2m_identity); 303 304 p2m_top_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE); 305 p2m_top_mfn_p_init(p2m_top_mfn_p); 306 307 p2m_top_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE); 308 p2m_top_mfn_init(p2m_top_mfn); 309 } else { 310 /* Reinitialise, mfn's all change after migration */ 311 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing); 312 p2m_mid_mfn_init(p2m_mid_identity_mfn, p2m_identity); 313 } 314 315 for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += P2M_PER_PAGE) { 316 unsigned topidx = p2m_top_index(pfn); 317 unsigned mididx = p2m_mid_index(pfn); 318 unsigned long **mid; 319 unsigned long *mid_mfn_p; 320 321 mid = p2m_top[topidx]; 322 mid_mfn_p = p2m_top_mfn_p[topidx]; 323 324 /* Don't bother allocating any mfn mid levels if 325 * they're just missing, just update the stored mfn, 326 * since all could have changed over a migrate. 327 */ 328 if (mid == p2m_mid_missing) { 329 BUG_ON(mididx); 330 BUG_ON(mid_mfn_p != p2m_mid_missing_mfn); 331 p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn); 332 pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE; 333 continue; 334 } 335 336 if (mid_mfn_p == p2m_mid_missing_mfn) { 337 /* 338 * XXX boot-time only! We should never find 339 * missing parts of the mfn tree after 340 * runtime. extend_brk() will BUG if we call 341 * it too late. 342 */ 343 mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE); 344 p2m_mid_mfn_init(mid_mfn_p, p2m_missing); 345 346 p2m_top_mfn_p[topidx] = mid_mfn_p; 347 } 348 349 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p); 350 mid_mfn_p[mididx] = virt_to_mfn(mid[mididx]); 351 } 352 } 353 354 void xen_setup_mfn_list_list(void) 355 { 356 if (xen_feature(XENFEAT_auto_translated_physmap)) 357 return; 358 359 BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info); 360 361 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = 362 virt_to_mfn(p2m_top_mfn); 363 HYPERVISOR_shared_info->arch.max_pfn = xen_max_p2m_pfn; 364 } 365 366 /* Set up p2m_top to point to the domain-builder provided p2m pages */ 367 void __init xen_build_dynamic_phys_to_machine(void) 368 { 369 unsigned long *mfn_list; 370 unsigned long max_pfn; 371 unsigned long pfn; 372 373 if (xen_feature(XENFEAT_auto_translated_physmap)) 374 return; 375 376 mfn_list = (unsigned long *)xen_start_info->mfn_list; 377 max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages); 378 xen_max_p2m_pfn = max_pfn; 379 380 p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE); 381 p2m_init(p2m_missing); 382 p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE); 383 p2m_init(p2m_identity); 384 385 p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE); 386 p2m_mid_init(p2m_mid_missing, p2m_missing); 387 p2m_mid_identity = extend_brk(PAGE_SIZE, PAGE_SIZE); 388 p2m_mid_init(p2m_mid_identity, p2m_identity); 389 390 p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE); 391 p2m_top_init(p2m_top); 392 393 /* 394 * The domain builder gives us a pre-constructed p2m array in 395 * mfn_list for all the pages initially given to us, so we just 396 * need to graft that into our tree structure. 397 */ 398 for (pfn = 0; pfn < max_pfn; pfn += P2M_PER_PAGE) { 399 unsigned topidx = p2m_top_index(pfn); 400 unsigned mididx = p2m_mid_index(pfn); 401 402 if (p2m_top[topidx] == p2m_mid_missing) { 403 unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE); 404 p2m_mid_init(mid, p2m_missing); 405 406 p2m_top[topidx] = mid; 407 } 408 409 /* 410 * As long as the mfn_list has enough entries to completely 411 * fill a p2m page, pointing into the array is ok. But if 412 * not the entries beyond the last pfn will be undefined. 413 */ 414 if (unlikely(pfn + P2M_PER_PAGE > max_pfn)) { 415 unsigned long p2midx; 416 417 p2midx = max_pfn % P2M_PER_PAGE; 418 for ( ; p2midx < P2M_PER_PAGE; p2midx++) 419 mfn_list[pfn + p2midx] = INVALID_P2M_ENTRY; 420 } 421 p2m_top[topidx][mididx] = &mfn_list[pfn]; 422 } 423 424 m2p_override_init(); 425 } 426 #ifdef CONFIG_X86_64 427 #include <linux/bootmem.h> 428 unsigned long __init xen_revector_p2m_tree(void) 429 { 430 unsigned long va_start; 431 unsigned long va_end; 432 unsigned long pfn; 433 unsigned long pfn_free = 0; 434 unsigned long *mfn_list = NULL; 435 unsigned long size; 436 437 va_start = xen_start_info->mfn_list; 438 /*We copy in increments of P2M_PER_PAGE * sizeof(unsigned long), 439 * so make sure it is rounded up to that */ 440 size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long)); 441 va_end = va_start + size; 442 443 /* If we were revectored already, don't do it again. */ 444 if (va_start <= __START_KERNEL_map && va_start >= __PAGE_OFFSET) 445 return 0; 446 447 mfn_list = alloc_bootmem_align(size, PAGE_SIZE); 448 if (!mfn_list) { 449 pr_warn("Could not allocate space for a new P2M tree!\n"); 450 return xen_start_info->mfn_list; 451 } 452 /* Fill it out with INVALID_P2M_ENTRY value */ 453 memset(mfn_list, 0xFF, size); 454 455 for (pfn = 0; pfn < ALIGN(MAX_DOMAIN_PAGES, P2M_PER_PAGE); pfn += P2M_PER_PAGE) { 456 unsigned topidx = p2m_top_index(pfn); 457 unsigned mididx; 458 unsigned long *mid_p; 459 460 if (!p2m_top[topidx]) 461 continue; 462 463 if (p2m_top[topidx] == p2m_mid_missing) 464 continue; 465 466 mididx = p2m_mid_index(pfn); 467 mid_p = p2m_top[topidx][mididx]; 468 if (!mid_p) 469 continue; 470 if ((mid_p == p2m_missing) || (mid_p == p2m_identity)) 471 continue; 472 473 if ((unsigned long)mid_p == INVALID_P2M_ENTRY) 474 continue; 475 476 /* The old va. Rebase it on mfn_list */ 477 if (mid_p >= (unsigned long *)va_start && mid_p <= (unsigned long *)va_end) { 478 unsigned long *new; 479 480 if (pfn_free > (size / sizeof(unsigned long))) { 481 WARN(1, "Only allocated for %ld pages, but we want %ld!\n", 482 size / sizeof(unsigned long), pfn_free); 483 return 0; 484 } 485 new = &mfn_list[pfn_free]; 486 487 copy_page(new, mid_p); 488 p2m_top[topidx][mididx] = &mfn_list[pfn_free]; 489 p2m_top_mfn_p[topidx][mididx] = virt_to_mfn(&mfn_list[pfn_free]); 490 491 pfn_free += P2M_PER_PAGE; 492 493 } 494 /* This should be the leafs allocated for identity from _brk. */ 495 } 496 return (unsigned long)mfn_list; 497 498 } 499 #else 500 unsigned long __init xen_revector_p2m_tree(void) 501 { 502 return 0; 503 } 504 #endif 505 unsigned long get_phys_to_machine(unsigned long pfn) 506 { 507 unsigned topidx, mididx, idx; 508 509 if (unlikely(pfn >= MAX_P2M_PFN)) 510 return IDENTITY_FRAME(pfn); 511 512 topidx = p2m_top_index(pfn); 513 mididx = p2m_mid_index(pfn); 514 idx = p2m_index(pfn); 515 516 /* 517 * The INVALID_P2M_ENTRY is filled in both p2m_*identity 518 * and in p2m_*missing, so returning the INVALID_P2M_ENTRY 519 * would be wrong. 520 */ 521 if (p2m_top[topidx][mididx] == p2m_identity) 522 return IDENTITY_FRAME(pfn); 523 524 return p2m_top[topidx][mididx][idx]; 525 } 526 EXPORT_SYMBOL_GPL(get_phys_to_machine); 527 528 static void *alloc_p2m_page(void) 529 { 530 return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT); 531 } 532 533 static void free_p2m_page(void *p) 534 { 535 free_page((unsigned long)p); 536 } 537 538 /* 539 * Fully allocate the p2m structure for a given pfn. We need to check 540 * that both the top and mid levels are allocated, and make sure the 541 * parallel mfn tree is kept in sync. We may race with other cpus, so 542 * the new pages are installed with cmpxchg; if we lose the race then 543 * simply free the page we allocated and use the one that's there. 544 */ 545 static bool alloc_p2m(unsigned long pfn) 546 { 547 unsigned topidx, mididx; 548 unsigned long ***top_p, **mid; 549 unsigned long *top_mfn_p, *mid_mfn; 550 551 topidx = p2m_top_index(pfn); 552 mididx = p2m_mid_index(pfn); 553 554 top_p = &p2m_top[topidx]; 555 mid = *top_p; 556 557 if (mid == p2m_mid_missing) { 558 /* Mid level is missing, allocate a new one */ 559 mid = alloc_p2m_page(); 560 if (!mid) 561 return false; 562 563 p2m_mid_init(mid, p2m_missing); 564 565 if (cmpxchg(top_p, p2m_mid_missing, mid) != p2m_mid_missing) 566 free_p2m_page(mid); 567 } 568 569 top_mfn_p = &p2m_top_mfn[topidx]; 570 mid_mfn = p2m_top_mfn_p[topidx]; 571 572 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p); 573 574 if (mid_mfn == p2m_mid_missing_mfn) { 575 /* Separately check the mid mfn level */ 576 unsigned long missing_mfn; 577 unsigned long mid_mfn_mfn; 578 579 mid_mfn = alloc_p2m_page(); 580 if (!mid_mfn) 581 return false; 582 583 p2m_mid_mfn_init(mid_mfn, p2m_missing); 584 585 missing_mfn = virt_to_mfn(p2m_mid_missing_mfn); 586 mid_mfn_mfn = virt_to_mfn(mid_mfn); 587 if (cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn) != missing_mfn) 588 free_p2m_page(mid_mfn); 589 else 590 p2m_top_mfn_p[topidx] = mid_mfn; 591 } 592 593 if (p2m_top[topidx][mididx] == p2m_identity || 594 p2m_top[topidx][mididx] == p2m_missing) { 595 /* p2m leaf page is missing */ 596 unsigned long *p2m; 597 unsigned long *p2m_orig = p2m_top[topidx][mididx]; 598 599 p2m = alloc_p2m_page(); 600 if (!p2m) 601 return false; 602 603 p2m_init(p2m); 604 605 if (cmpxchg(&mid[mididx], p2m_orig, p2m) != p2m_orig) 606 free_p2m_page(p2m); 607 else 608 mid_mfn[mididx] = virt_to_mfn(p2m); 609 } 610 611 return true; 612 } 613 614 static bool __init early_alloc_p2m(unsigned long pfn, bool check_boundary) 615 { 616 unsigned topidx, mididx, idx; 617 unsigned long *p2m; 618 unsigned long *mid_mfn_p; 619 620 topidx = p2m_top_index(pfn); 621 mididx = p2m_mid_index(pfn); 622 idx = p2m_index(pfn); 623 624 /* Pfff.. No boundary cross-over, lets get out. */ 625 if (!idx && check_boundary) 626 return false; 627 628 WARN(p2m_top[topidx][mididx] == p2m_identity, 629 "P2M[%d][%d] == IDENTITY, should be MISSING (or alloced)!\n", 630 topidx, mididx); 631 632 /* 633 * Could be done by xen_build_dynamic_phys_to_machine.. 634 */ 635 if (p2m_top[topidx][mididx] != p2m_missing) 636 return false; 637 638 /* Boundary cross-over for the edges: */ 639 p2m = extend_brk(PAGE_SIZE, PAGE_SIZE); 640 641 p2m_init(p2m); 642 643 p2m_top[topidx][mididx] = p2m; 644 645 /* For save/restore we need to MFN of the P2M saved */ 646 647 mid_mfn_p = p2m_top_mfn_p[topidx]; 648 WARN(mid_mfn_p[mididx] != virt_to_mfn(p2m_missing), 649 "P2M_TOP_P[%d][%d] != MFN of p2m_missing!\n", 650 topidx, mididx); 651 mid_mfn_p[mididx] = virt_to_mfn(p2m); 652 653 return true; 654 } 655 656 static bool __init early_alloc_p2m_middle(unsigned long pfn) 657 { 658 unsigned topidx = p2m_top_index(pfn); 659 unsigned long *mid_mfn_p; 660 unsigned long **mid; 661 662 mid = p2m_top[topidx]; 663 mid_mfn_p = p2m_top_mfn_p[topidx]; 664 if (mid == p2m_mid_missing) { 665 mid = extend_brk(PAGE_SIZE, PAGE_SIZE); 666 667 p2m_mid_init(mid, p2m_missing); 668 669 p2m_top[topidx] = mid; 670 671 BUG_ON(mid_mfn_p != p2m_mid_missing_mfn); 672 } 673 /* And the save/restore P2M tables.. */ 674 if (mid_mfn_p == p2m_mid_missing_mfn) { 675 mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE); 676 p2m_mid_mfn_init(mid_mfn_p, p2m_missing); 677 678 p2m_top_mfn_p[topidx] = mid_mfn_p; 679 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p); 680 /* Note: we don't set mid_mfn_p[midix] here, 681 * look in early_alloc_p2m() */ 682 } 683 return true; 684 } 685 686 /* 687 * Skim over the P2M tree looking at pages that are either filled with 688 * INVALID_P2M_ENTRY or with 1:1 PFNs. If found, re-use that page and 689 * replace the P2M leaf with a p2m_missing or p2m_identity. 690 * Stick the old page in the new P2M tree location. 691 */ 692 bool __init early_can_reuse_p2m_middle(unsigned long set_pfn, unsigned long set_mfn) 693 { 694 unsigned topidx; 695 unsigned mididx; 696 unsigned ident_pfns; 697 unsigned inv_pfns; 698 unsigned long *p2m; 699 unsigned long *mid_mfn_p; 700 unsigned idx; 701 unsigned long pfn; 702 703 /* We only look when this entails a P2M middle layer */ 704 if (p2m_index(set_pfn)) 705 return false; 706 707 for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn += P2M_PER_PAGE) { 708 topidx = p2m_top_index(pfn); 709 710 if (!p2m_top[topidx]) 711 continue; 712 713 if (p2m_top[topidx] == p2m_mid_missing) 714 continue; 715 716 mididx = p2m_mid_index(pfn); 717 p2m = p2m_top[topidx][mididx]; 718 if (!p2m) 719 continue; 720 721 if ((p2m == p2m_missing) || (p2m == p2m_identity)) 722 continue; 723 724 if ((unsigned long)p2m == INVALID_P2M_ENTRY) 725 continue; 726 727 ident_pfns = 0; 728 inv_pfns = 0; 729 for (idx = 0; idx < P2M_PER_PAGE; idx++) { 730 /* IDENTITY_PFNs are 1:1 */ 731 if (p2m[idx] == IDENTITY_FRAME(pfn + idx)) 732 ident_pfns++; 733 else if (p2m[idx] == INVALID_P2M_ENTRY) 734 inv_pfns++; 735 else 736 break; 737 } 738 if ((ident_pfns == P2M_PER_PAGE) || (inv_pfns == P2M_PER_PAGE)) 739 goto found; 740 } 741 return false; 742 found: 743 /* Found one, replace old with p2m_identity or p2m_missing */ 744 p2m_top[topidx][mididx] = (ident_pfns ? p2m_identity : p2m_missing); 745 /* And the other for save/restore.. */ 746 mid_mfn_p = p2m_top_mfn_p[topidx]; 747 /* NOTE: Even if it is a p2m_identity it should still be point to 748 * a page filled with INVALID_P2M_ENTRY entries. */ 749 mid_mfn_p[mididx] = virt_to_mfn(p2m_missing); 750 751 /* Reset where we want to stick the old page in. */ 752 topidx = p2m_top_index(set_pfn); 753 mididx = p2m_mid_index(set_pfn); 754 755 /* This shouldn't happen */ 756 if (WARN_ON(p2m_top[topidx] == p2m_mid_missing)) 757 early_alloc_p2m_middle(set_pfn); 758 759 if (WARN_ON(p2m_top[topidx][mididx] != p2m_missing)) 760 return false; 761 762 p2m_init(p2m); 763 p2m_top[topidx][mididx] = p2m; 764 mid_mfn_p = p2m_top_mfn_p[topidx]; 765 mid_mfn_p[mididx] = virt_to_mfn(p2m); 766 767 return true; 768 } 769 bool __init early_set_phys_to_machine(unsigned long pfn, unsigned long mfn) 770 { 771 if (unlikely(!__set_phys_to_machine(pfn, mfn))) { 772 if (!early_alloc_p2m_middle(pfn)) 773 return false; 774 775 if (early_can_reuse_p2m_middle(pfn, mfn)) 776 return __set_phys_to_machine(pfn, mfn); 777 778 if (!early_alloc_p2m(pfn, false /* boundary crossover OK!*/)) 779 return false; 780 781 if (!__set_phys_to_machine(pfn, mfn)) 782 return false; 783 } 784 785 return true; 786 } 787 788 static void __init early_split_p2m(unsigned long pfn) 789 { 790 unsigned long mididx, idx; 791 792 mididx = p2m_mid_index(pfn); 793 idx = p2m_index(pfn); 794 795 /* 796 * Allocate new middle and leaf pages if this pfn lies in the 797 * middle of one. 798 */ 799 if (mididx || idx) 800 early_alloc_p2m_middle(pfn); 801 if (idx) 802 early_alloc_p2m(pfn, false); 803 } 804 805 unsigned long __init set_phys_range_identity(unsigned long pfn_s, 806 unsigned long pfn_e) 807 { 808 unsigned long pfn; 809 810 if (unlikely(pfn_s >= MAX_P2M_PFN)) 811 return 0; 812 813 if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) 814 return pfn_e - pfn_s; 815 816 if (pfn_s > pfn_e) 817 return 0; 818 819 if (pfn_e > MAX_P2M_PFN) 820 pfn_e = MAX_P2M_PFN; 821 822 early_split_p2m(pfn_s); 823 early_split_p2m(pfn_e); 824 825 for (pfn = pfn_s; pfn < pfn_e;) { 826 unsigned topidx = p2m_top_index(pfn); 827 unsigned mididx = p2m_mid_index(pfn); 828 829 if (!__set_phys_to_machine(pfn, IDENTITY_FRAME(pfn))) 830 break; 831 pfn++; 832 833 /* 834 * If the PFN was set to a middle or leaf identity 835 * page the remainder must also be identity, so skip 836 * ahead to the next middle or leaf entry. 837 */ 838 if (p2m_top[topidx] == p2m_mid_identity) 839 pfn = ALIGN(pfn, P2M_MID_PER_PAGE * P2M_PER_PAGE); 840 else if (p2m_top[topidx][mididx] == p2m_identity) 841 pfn = ALIGN(pfn, P2M_PER_PAGE); 842 } 843 844 if (!WARN((pfn - pfn_s) != (pfn_e - pfn_s), 845 "Identity mapping failed. We are %ld short of 1-1 mappings!\n", 846 (pfn_e - pfn_s) - (pfn - pfn_s))) 847 printk(KERN_DEBUG "1-1 mapping on %lx->%lx\n", pfn_s, pfn); 848 849 return pfn - pfn_s; 850 } 851 852 /* Try to install p2m mapping; fail if intermediate bits missing */ 853 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn) 854 { 855 unsigned topidx, mididx, idx; 856 857 /* don't track P2M changes in autotranslate guests */ 858 if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) 859 return true; 860 861 if (unlikely(pfn >= MAX_P2M_PFN)) { 862 BUG_ON(mfn != INVALID_P2M_ENTRY); 863 return true; 864 } 865 866 topidx = p2m_top_index(pfn); 867 mididx = p2m_mid_index(pfn); 868 idx = p2m_index(pfn); 869 870 /* For sparse holes were the p2m leaf has real PFN along with 871 * PCI holes, stick in the PFN as the MFN value. 872 * 873 * set_phys_range_identity() will have allocated new middle 874 * and leaf pages as required so an existing p2m_mid_missing 875 * or p2m_missing mean that whole range will be identity so 876 * these can be switched to p2m_mid_identity or p2m_identity. 877 */ 878 if (mfn != INVALID_P2M_ENTRY && (mfn & IDENTITY_FRAME_BIT)) { 879 if (p2m_top[topidx] == p2m_mid_identity) 880 return true; 881 882 if (p2m_top[topidx] == p2m_mid_missing) { 883 WARN_ON(cmpxchg(&p2m_top[topidx], p2m_mid_missing, 884 p2m_mid_identity) != p2m_mid_missing); 885 return true; 886 } 887 888 if (p2m_top[topidx][mididx] == p2m_identity) 889 return true; 890 891 /* Swap over from MISSING to IDENTITY if needed. */ 892 if (p2m_top[topidx][mididx] == p2m_missing) { 893 WARN_ON(cmpxchg(&p2m_top[topidx][mididx], p2m_missing, 894 p2m_identity) != p2m_missing); 895 return true; 896 } 897 } 898 899 if (p2m_top[topidx][mididx] == p2m_missing) 900 return mfn == INVALID_P2M_ENTRY; 901 902 p2m_top[topidx][mididx][idx] = mfn; 903 904 return true; 905 } 906 907 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn) 908 { 909 if (unlikely(!__set_phys_to_machine(pfn, mfn))) { 910 if (!alloc_p2m(pfn)) 911 return false; 912 913 if (!__set_phys_to_machine(pfn, mfn)) 914 return false; 915 } 916 917 return true; 918 } 919 920 #define M2P_OVERRIDE_HASH_SHIFT 10 921 #define M2P_OVERRIDE_HASH (1 << M2P_OVERRIDE_HASH_SHIFT) 922 923 static RESERVE_BRK_ARRAY(struct list_head, m2p_overrides, M2P_OVERRIDE_HASH); 924 static DEFINE_SPINLOCK(m2p_override_lock); 925 926 static void __init m2p_override_init(void) 927 { 928 unsigned i; 929 930 m2p_overrides = extend_brk(sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH, 931 sizeof(unsigned long)); 932 933 for (i = 0; i < M2P_OVERRIDE_HASH; i++) 934 INIT_LIST_HEAD(&m2p_overrides[i]); 935 } 936 937 static unsigned long mfn_hash(unsigned long mfn) 938 { 939 return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT); 940 } 941 942 int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops, 943 struct gnttab_map_grant_ref *kmap_ops, 944 struct page **pages, unsigned int count) 945 { 946 int i, ret = 0; 947 bool lazy = false; 948 pte_t *pte; 949 950 if (xen_feature(XENFEAT_auto_translated_physmap)) 951 return 0; 952 953 if (kmap_ops && 954 !in_interrupt() && 955 paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) { 956 arch_enter_lazy_mmu_mode(); 957 lazy = true; 958 } 959 960 for (i = 0; i < count; i++) { 961 unsigned long mfn, pfn; 962 963 /* Do not add to override if the map failed. */ 964 if (map_ops[i].status) 965 continue; 966 967 if (map_ops[i].flags & GNTMAP_contains_pte) { 968 pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) + 969 (map_ops[i].host_addr & ~PAGE_MASK)); 970 mfn = pte_mfn(*pte); 971 } else { 972 mfn = PFN_DOWN(map_ops[i].dev_bus_addr); 973 } 974 pfn = page_to_pfn(pages[i]); 975 976 WARN_ON(PagePrivate(pages[i])); 977 SetPagePrivate(pages[i]); 978 set_page_private(pages[i], mfn); 979 pages[i]->index = pfn_to_mfn(pfn); 980 981 if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) { 982 ret = -ENOMEM; 983 goto out; 984 } 985 986 if (kmap_ops) { 987 ret = m2p_add_override(mfn, pages[i], &kmap_ops[i]); 988 if (ret) 989 goto out; 990 } 991 } 992 993 out: 994 if (lazy) 995 arch_leave_lazy_mmu_mode(); 996 997 return ret; 998 } 999 EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping); 1000 1001 /* Add an MFN override for a particular page */ 1002 int m2p_add_override(unsigned long mfn, struct page *page, 1003 struct gnttab_map_grant_ref *kmap_op) 1004 { 1005 unsigned long flags; 1006 unsigned long pfn; 1007 unsigned long uninitialized_var(address); 1008 unsigned level; 1009 pte_t *ptep = NULL; 1010 1011 pfn = page_to_pfn(page); 1012 if (!PageHighMem(page)) { 1013 address = (unsigned long)__va(pfn << PAGE_SHIFT); 1014 ptep = lookup_address(address, &level); 1015 if (WARN(ptep == NULL || level != PG_LEVEL_4K, 1016 "m2p_add_override: pfn %lx not mapped", pfn)) 1017 return -EINVAL; 1018 } 1019 1020 if (kmap_op != NULL) { 1021 if (!PageHighMem(page)) { 1022 struct multicall_space mcs = 1023 xen_mc_entry(sizeof(*kmap_op)); 1024 1025 MULTI_grant_table_op(mcs.mc, 1026 GNTTABOP_map_grant_ref, kmap_op, 1); 1027 1028 xen_mc_issue(PARAVIRT_LAZY_MMU); 1029 } 1030 } 1031 spin_lock_irqsave(&m2p_override_lock, flags); 1032 list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]); 1033 spin_unlock_irqrestore(&m2p_override_lock, flags); 1034 1035 /* p2m(m2p(mfn)) == mfn: the mfn is already present somewhere in 1036 * this domain. Set the FOREIGN_FRAME_BIT in the p2m for the other 1037 * pfn so that the following mfn_to_pfn(mfn) calls will return the 1038 * pfn from the m2p_override (the backend pfn) instead. 1039 * We need to do this because the pages shared by the frontend 1040 * (xen-blkfront) can be already locked (lock_page, called by 1041 * do_read_cache_page); when the userspace backend tries to use them 1042 * with direct_IO, mfn_to_pfn returns the pfn of the frontend, so 1043 * do_blockdev_direct_IO is going to try to lock the same pages 1044 * again resulting in a deadlock. 1045 * As a side effect get_user_pages_fast might not be safe on the 1046 * frontend pages while they are being shared with the backend, 1047 * because mfn_to_pfn (that ends up being called by GUPF) will 1048 * return the backend pfn rather than the frontend pfn. */ 1049 pfn = mfn_to_pfn_no_overrides(mfn); 1050 if (get_phys_to_machine(pfn) == mfn) 1051 set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)); 1052 1053 return 0; 1054 } 1055 EXPORT_SYMBOL_GPL(m2p_add_override); 1056 1057 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops, 1058 struct gnttab_map_grant_ref *kmap_ops, 1059 struct page **pages, unsigned int count) 1060 { 1061 int i, ret = 0; 1062 bool lazy = false; 1063 1064 if (xen_feature(XENFEAT_auto_translated_physmap)) 1065 return 0; 1066 1067 if (kmap_ops && 1068 !in_interrupt() && 1069 paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) { 1070 arch_enter_lazy_mmu_mode(); 1071 lazy = true; 1072 } 1073 1074 for (i = 0; i < count; i++) { 1075 unsigned long mfn = get_phys_to_machine(page_to_pfn(pages[i])); 1076 unsigned long pfn = page_to_pfn(pages[i]); 1077 1078 if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) { 1079 ret = -EINVAL; 1080 goto out; 1081 } 1082 1083 set_page_private(pages[i], INVALID_P2M_ENTRY); 1084 WARN_ON(!PagePrivate(pages[i])); 1085 ClearPagePrivate(pages[i]); 1086 set_phys_to_machine(pfn, pages[i]->index); 1087 1088 if (kmap_ops) 1089 ret = m2p_remove_override(pages[i], &kmap_ops[i], mfn); 1090 if (ret) 1091 goto out; 1092 } 1093 1094 out: 1095 if (lazy) 1096 arch_leave_lazy_mmu_mode(); 1097 return ret; 1098 } 1099 EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping); 1100 1101 int m2p_remove_override(struct page *page, 1102 struct gnttab_map_grant_ref *kmap_op, 1103 unsigned long mfn) 1104 { 1105 unsigned long flags; 1106 unsigned long pfn; 1107 unsigned long uninitialized_var(address); 1108 unsigned level; 1109 pte_t *ptep = NULL; 1110 1111 pfn = page_to_pfn(page); 1112 1113 if (!PageHighMem(page)) { 1114 address = (unsigned long)__va(pfn << PAGE_SHIFT); 1115 ptep = lookup_address(address, &level); 1116 1117 if (WARN(ptep == NULL || level != PG_LEVEL_4K, 1118 "m2p_remove_override: pfn %lx not mapped", pfn)) 1119 return -EINVAL; 1120 } 1121 1122 spin_lock_irqsave(&m2p_override_lock, flags); 1123 list_del(&page->lru); 1124 spin_unlock_irqrestore(&m2p_override_lock, flags); 1125 1126 if (kmap_op != NULL) { 1127 if (!PageHighMem(page)) { 1128 struct multicall_space mcs; 1129 struct gnttab_unmap_and_replace *unmap_op; 1130 struct page *scratch_page = get_balloon_scratch_page(); 1131 unsigned long scratch_page_address = (unsigned long) 1132 __va(page_to_pfn(scratch_page) << PAGE_SHIFT); 1133 1134 /* 1135 * It might be that we queued all the m2p grant table 1136 * hypercalls in a multicall, then m2p_remove_override 1137 * get called before the multicall has actually been 1138 * issued. In this case handle is going to -1 because 1139 * it hasn't been modified yet. 1140 */ 1141 if (kmap_op->handle == -1) 1142 xen_mc_flush(); 1143 /* 1144 * Now if kmap_op->handle is negative it means that the 1145 * hypercall actually returned an error. 1146 */ 1147 if (kmap_op->handle == GNTST_general_error) { 1148 printk(KERN_WARNING "m2p_remove_override: " 1149 "pfn %lx mfn %lx, failed to modify kernel mappings", 1150 pfn, mfn); 1151 put_balloon_scratch_page(); 1152 return -1; 1153 } 1154 1155 xen_mc_batch(); 1156 1157 mcs = __xen_mc_entry( 1158 sizeof(struct gnttab_unmap_and_replace)); 1159 unmap_op = mcs.args; 1160 unmap_op->host_addr = kmap_op->host_addr; 1161 unmap_op->new_addr = scratch_page_address; 1162 unmap_op->handle = kmap_op->handle; 1163 1164 MULTI_grant_table_op(mcs.mc, 1165 GNTTABOP_unmap_and_replace, unmap_op, 1); 1166 1167 mcs = __xen_mc_entry(0); 1168 MULTI_update_va_mapping(mcs.mc, scratch_page_address, 1169 pfn_pte(page_to_pfn(scratch_page), 1170 PAGE_KERNEL_RO), 0); 1171 1172 xen_mc_issue(PARAVIRT_LAZY_MMU); 1173 1174 kmap_op->host_addr = 0; 1175 put_balloon_scratch_page(); 1176 } 1177 } 1178 1179 /* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present 1180 * somewhere in this domain, even before being added to the 1181 * m2p_override (see comment above in m2p_add_override). 1182 * If there are no other entries in the m2p_override corresponding 1183 * to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for 1184 * the original pfn (the one shared by the frontend): the backend 1185 * cannot do any IO on this page anymore because it has been 1186 * unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of 1187 * the original pfn causes mfn_to_pfn(mfn) to return the frontend 1188 * pfn again. */ 1189 mfn &= ~FOREIGN_FRAME_BIT; 1190 pfn = mfn_to_pfn_no_overrides(mfn); 1191 if (get_phys_to_machine(pfn) == FOREIGN_FRAME(mfn) && 1192 m2p_find_override(mfn) == NULL) 1193 set_phys_to_machine(pfn, mfn); 1194 1195 return 0; 1196 } 1197 EXPORT_SYMBOL_GPL(m2p_remove_override); 1198 1199 struct page *m2p_find_override(unsigned long mfn) 1200 { 1201 unsigned long flags; 1202 struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)]; 1203 struct page *p, *ret; 1204 1205 ret = NULL; 1206 1207 spin_lock_irqsave(&m2p_override_lock, flags); 1208 1209 list_for_each_entry(p, bucket, lru) { 1210 if (page_private(p) == mfn) { 1211 ret = p; 1212 break; 1213 } 1214 } 1215 1216 spin_unlock_irqrestore(&m2p_override_lock, flags); 1217 1218 return ret; 1219 } 1220 1221 unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn) 1222 { 1223 struct page *p = m2p_find_override(mfn); 1224 unsigned long ret = pfn; 1225 1226 if (p) 1227 ret = page_to_pfn(p); 1228 1229 return ret; 1230 } 1231 EXPORT_SYMBOL_GPL(m2p_find_override_pfn); 1232 1233 #ifdef CONFIG_XEN_DEBUG_FS 1234 #include <linux/debugfs.h> 1235 #include "debugfs.h" 1236 static int p2m_dump_show(struct seq_file *m, void *v) 1237 { 1238 static const char * const level_name[] = { "top", "middle", 1239 "entry", "abnormal", "error"}; 1240 #define TYPE_IDENTITY 0 1241 #define TYPE_MISSING 1 1242 #define TYPE_PFN 2 1243 #define TYPE_UNKNOWN 3 1244 static const char * const type_name[] = { 1245 [TYPE_IDENTITY] = "identity", 1246 [TYPE_MISSING] = "missing", 1247 [TYPE_PFN] = "pfn", 1248 [TYPE_UNKNOWN] = "abnormal"}; 1249 unsigned long pfn, prev_pfn_type = 0, prev_pfn_level = 0; 1250 unsigned int uninitialized_var(prev_level); 1251 unsigned int uninitialized_var(prev_type); 1252 1253 if (!p2m_top) 1254 return 0; 1255 1256 for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn++) { 1257 unsigned topidx = p2m_top_index(pfn); 1258 unsigned mididx = p2m_mid_index(pfn); 1259 unsigned idx = p2m_index(pfn); 1260 unsigned lvl, type; 1261 1262 lvl = 4; 1263 type = TYPE_UNKNOWN; 1264 if (p2m_top[topidx] == p2m_mid_missing) { 1265 lvl = 0; type = TYPE_MISSING; 1266 } else if (p2m_top[topidx] == NULL) { 1267 lvl = 0; type = TYPE_UNKNOWN; 1268 } else if (p2m_top[topidx][mididx] == NULL) { 1269 lvl = 1; type = TYPE_UNKNOWN; 1270 } else if (p2m_top[topidx][mididx] == p2m_identity) { 1271 lvl = 1; type = TYPE_IDENTITY; 1272 } else if (p2m_top[topidx][mididx] == p2m_missing) { 1273 lvl = 1; type = TYPE_MISSING; 1274 } else if (p2m_top[topidx][mididx][idx] == 0) { 1275 lvl = 2; type = TYPE_UNKNOWN; 1276 } else if (p2m_top[topidx][mididx][idx] == IDENTITY_FRAME(pfn)) { 1277 lvl = 2; type = TYPE_IDENTITY; 1278 } else if (p2m_top[topidx][mididx][idx] == INVALID_P2M_ENTRY) { 1279 lvl = 2; type = TYPE_MISSING; 1280 } else if (p2m_top[topidx][mididx][idx] == pfn) { 1281 lvl = 2; type = TYPE_PFN; 1282 } else if (p2m_top[topidx][mididx][idx] != pfn) { 1283 lvl = 2; type = TYPE_PFN; 1284 } 1285 if (pfn == 0) { 1286 prev_level = lvl; 1287 prev_type = type; 1288 } 1289 if (pfn == MAX_DOMAIN_PAGES-1) { 1290 lvl = 3; 1291 type = TYPE_UNKNOWN; 1292 } 1293 if (prev_type != type) { 1294 seq_printf(m, " [0x%lx->0x%lx] %s\n", 1295 prev_pfn_type, pfn, type_name[prev_type]); 1296 prev_pfn_type = pfn; 1297 prev_type = type; 1298 } 1299 if (prev_level != lvl) { 1300 seq_printf(m, " [0x%lx->0x%lx] level %s\n", 1301 prev_pfn_level, pfn, level_name[prev_level]); 1302 prev_pfn_level = pfn; 1303 prev_level = lvl; 1304 } 1305 } 1306 return 0; 1307 #undef TYPE_IDENTITY 1308 #undef TYPE_MISSING 1309 #undef TYPE_PFN 1310 #undef TYPE_UNKNOWN 1311 } 1312 1313 static int p2m_dump_open(struct inode *inode, struct file *filp) 1314 { 1315 return single_open(filp, p2m_dump_show, NULL); 1316 } 1317 1318 static const struct file_operations p2m_dump_fops = { 1319 .open = p2m_dump_open, 1320 .read = seq_read, 1321 .llseek = seq_lseek, 1322 .release = single_release, 1323 }; 1324 1325 static struct dentry *d_mmu_debug; 1326 1327 static int __init xen_p2m_debugfs(void) 1328 { 1329 struct dentry *d_xen = xen_init_debugfs(); 1330 1331 if (d_xen == NULL) 1332 return -ENOMEM; 1333 1334 d_mmu_debug = debugfs_create_dir("mmu", d_xen); 1335 1336 debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops); 1337 return 0; 1338 } 1339 fs_initcall(xen_p2m_debugfs); 1340 #endif /* CONFIG_XEN_DEBUG_FS */ 1341