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_missing p2m_missing 143 * /------------------\ /------------\ 144 * | [p2m_mid_missing]+---->| ~0, ~0, ~0 | 145 * | [p2m_mid_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> 164 165 #include "xen-ops.h" 166 167 static void __init m2p_override_init(void); 168 169 unsigned long xen_max_p2m_pfn __read_mostly; 170 171 #define P2M_PER_PAGE (PAGE_SIZE / sizeof(unsigned long)) 172 #define P2M_MID_PER_PAGE (PAGE_SIZE / sizeof(unsigned long *)) 173 #define P2M_TOP_PER_PAGE (PAGE_SIZE / sizeof(unsigned long **)) 174 175 #define MAX_P2M_PFN (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE) 176 177 /* Placeholders for holes in the address space */ 178 static RESERVE_BRK_ARRAY(unsigned long, p2m_missing, P2M_PER_PAGE); 179 static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_missing, P2M_MID_PER_PAGE); 180 static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_missing_mfn, P2M_MID_PER_PAGE); 181 182 static RESERVE_BRK_ARRAY(unsigned long **, p2m_top, P2M_TOP_PER_PAGE); 183 static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, P2M_TOP_PER_PAGE); 184 static RESERVE_BRK_ARRAY(unsigned long *, p2m_top_mfn_p, P2M_TOP_PER_PAGE); 185 186 static RESERVE_BRK_ARRAY(unsigned long, p2m_identity, P2M_PER_PAGE); 187 188 RESERVE_BRK(p2m_mid, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE))); 189 RESERVE_BRK(p2m_mid_mfn, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE))); 190 191 /* We might hit two boundary violations at the start and end, at max each 192 * boundary violation will require three middle nodes. */ 193 RESERVE_BRK(p2m_mid_identity, PAGE_SIZE * 2 * 3); 194 195 static inline unsigned p2m_top_index(unsigned long pfn) 196 { 197 BUG_ON(pfn >= MAX_P2M_PFN); 198 return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE); 199 } 200 201 static inline unsigned p2m_mid_index(unsigned long pfn) 202 { 203 return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE; 204 } 205 206 static inline unsigned p2m_index(unsigned long pfn) 207 { 208 return pfn % P2M_PER_PAGE; 209 } 210 211 static void p2m_top_init(unsigned long ***top) 212 { 213 unsigned i; 214 215 for (i = 0; i < P2M_TOP_PER_PAGE; i++) 216 top[i] = p2m_mid_missing; 217 } 218 219 static void p2m_top_mfn_init(unsigned long *top) 220 { 221 unsigned i; 222 223 for (i = 0; i < P2M_TOP_PER_PAGE; i++) 224 top[i] = virt_to_mfn(p2m_mid_missing_mfn); 225 } 226 227 static void p2m_top_mfn_p_init(unsigned long **top) 228 { 229 unsigned i; 230 231 for (i = 0; i < P2M_TOP_PER_PAGE; i++) 232 top[i] = p2m_mid_missing_mfn; 233 } 234 235 static void p2m_mid_init(unsigned long **mid) 236 { 237 unsigned i; 238 239 for (i = 0; i < P2M_MID_PER_PAGE; i++) 240 mid[i] = p2m_missing; 241 } 242 243 static void p2m_mid_mfn_init(unsigned long *mid) 244 { 245 unsigned i; 246 247 for (i = 0; i < P2M_MID_PER_PAGE; i++) 248 mid[i] = virt_to_mfn(p2m_missing); 249 } 250 251 static void p2m_init(unsigned long *p2m) 252 { 253 unsigned i; 254 255 for (i = 0; i < P2M_MID_PER_PAGE; i++) 256 p2m[i] = INVALID_P2M_ENTRY; 257 } 258 259 /* 260 * Build the parallel p2m_top_mfn and p2m_mid_mfn structures 261 * 262 * This is called both at boot time, and after resuming from suspend: 263 * - At boot time we're called very early, and must use extend_brk() 264 * to allocate memory. 265 * 266 * - After resume we're called from within stop_machine, but the mfn 267 * tree should alreay be completely allocated. 268 */ 269 void __ref xen_build_mfn_list_list(void) 270 { 271 unsigned long pfn; 272 273 /* Pre-initialize p2m_top_mfn to be completely missing */ 274 if (p2m_top_mfn == NULL) { 275 p2m_mid_missing_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE); 276 p2m_mid_mfn_init(p2m_mid_missing_mfn); 277 278 p2m_top_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE); 279 p2m_top_mfn_p_init(p2m_top_mfn_p); 280 281 p2m_top_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE); 282 p2m_top_mfn_init(p2m_top_mfn); 283 } else { 284 /* Reinitialise, mfn's all change after migration */ 285 p2m_mid_mfn_init(p2m_mid_missing_mfn); 286 } 287 288 for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += P2M_PER_PAGE) { 289 unsigned topidx = p2m_top_index(pfn); 290 unsigned mididx = p2m_mid_index(pfn); 291 unsigned long **mid; 292 unsigned long *mid_mfn_p; 293 294 mid = p2m_top[topidx]; 295 mid_mfn_p = p2m_top_mfn_p[topidx]; 296 297 /* Don't bother allocating any mfn mid levels if 298 * they're just missing, just update the stored mfn, 299 * since all could have changed over a migrate. 300 */ 301 if (mid == p2m_mid_missing) { 302 BUG_ON(mididx); 303 BUG_ON(mid_mfn_p != p2m_mid_missing_mfn); 304 p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn); 305 pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE; 306 continue; 307 } 308 309 if (mid_mfn_p == p2m_mid_missing_mfn) { 310 /* 311 * XXX boot-time only! We should never find 312 * missing parts of the mfn tree after 313 * runtime. extend_brk() will BUG if we call 314 * it too late. 315 */ 316 mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE); 317 p2m_mid_mfn_init(mid_mfn_p); 318 319 p2m_top_mfn_p[topidx] = mid_mfn_p; 320 } 321 322 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p); 323 mid_mfn_p[mididx] = virt_to_mfn(mid[mididx]); 324 } 325 } 326 327 void xen_setup_mfn_list_list(void) 328 { 329 BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info); 330 331 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = 332 virt_to_mfn(p2m_top_mfn); 333 HYPERVISOR_shared_info->arch.max_pfn = xen_max_p2m_pfn; 334 } 335 336 /* Set up p2m_top to point to the domain-builder provided p2m pages */ 337 void __init xen_build_dynamic_phys_to_machine(void) 338 { 339 unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list; 340 unsigned long max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages); 341 unsigned long pfn; 342 343 xen_max_p2m_pfn = max_pfn; 344 345 p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE); 346 p2m_init(p2m_missing); 347 348 p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE); 349 p2m_mid_init(p2m_mid_missing); 350 351 p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE); 352 p2m_top_init(p2m_top); 353 354 p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE); 355 p2m_init(p2m_identity); 356 357 /* 358 * The domain builder gives us a pre-constructed p2m array in 359 * mfn_list for all the pages initially given to us, so we just 360 * need to graft that into our tree structure. 361 */ 362 for (pfn = 0; pfn < max_pfn; pfn += P2M_PER_PAGE) { 363 unsigned topidx = p2m_top_index(pfn); 364 unsigned mididx = p2m_mid_index(pfn); 365 366 if (p2m_top[topidx] == p2m_mid_missing) { 367 unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE); 368 p2m_mid_init(mid); 369 370 p2m_top[topidx] = mid; 371 } 372 373 /* 374 * As long as the mfn_list has enough entries to completely 375 * fill a p2m page, pointing into the array is ok. But if 376 * not the entries beyond the last pfn will be undefined. 377 */ 378 if (unlikely(pfn + P2M_PER_PAGE > max_pfn)) { 379 unsigned long p2midx; 380 381 p2midx = max_pfn % P2M_PER_PAGE; 382 for ( ; p2midx < P2M_PER_PAGE; p2midx++) 383 mfn_list[pfn + p2midx] = INVALID_P2M_ENTRY; 384 } 385 p2m_top[topidx][mididx] = &mfn_list[pfn]; 386 } 387 388 m2p_override_init(); 389 } 390 391 unsigned long get_phys_to_machine(unsigned long pfn) 392 { 393 unsigned topidx, mididx, idx; 394 395 if (unlikely(pfn >= MAX_P2M_PFN)) 396 return INVALID_P2M_ENTRY; 397 398 topidx = p2m_top_index(pfn); 399 mididx = p2m_mid_index(pfn); 400 idx = p2m_index(pfn); 401 402 /* 403 * The INVALID_P2M_ENTRY is filled in both p2m_*identity 404 * and in p2m_*missing, so returning the INVALID_P2M_ENTRY 405 * would be wrong. 406 */ 407 if (p2m_top[topidx][mididx] == p2m_identity) 408 return IDENTITY_FRAME(pfn); 409 410 return p2m_top[topidx][mididx][idx]; 411 } 412 EXPORT_SYMBOL_GPL(get_phys_to_machine); 413 414 static void *alloc_p2m_page(void) 415 { 416 return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT); 417 } 418 419 static void free_p2m_page(void *p) 420 { 421 free_page((unsigned long)p); 422 } 423 424 /* 425 * Fully allocate the p2m structure for a given pfn. We need to check 426 * that both the top and mid levels are allocated, and make sure the 427 * parallel mfn tree is kept in sync. We may race with other cpus, so 428 * the new pages are installed with cmpxchg; if we lose the race then 429 * simply free the page we allocated and use the one that's there. 430 */ 431 static bool alloc_p2m(unsigned long pfn) 432 { 433 unsigned topidx, mididx; 434 unsigned long ***top_p, **mid; 435 unsigned long *top_mfn_p, *mid_mfn; 436 437 topidx = p2m_top_index(pfn); 438 mididx = p2m_mid_index(pfn); 439 440 top_p = &p2m_top[topidx]; 441 mid = *top_p; 442 443 if (mid == p2m_mid_missing) { 444 /* Mid level is missing, allocate a new one */ 445 mid = alloc_p2m_page(); 446 if (!mid) 447 return false; 448 449 p2m_mid_init(mid); 450 451 if (cmpxchg(top_p, p2m_mid_missing, mid) != p2m_mid_missing) 452 free_p2m_page(mid); 453 } 454 455 top_mfn_p = &p2m_top_mfn[topidx]; 456 mid_mfn = p2m_top_mfn_p[topidx]; 457 458 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p); 459 460 if (mid_mfn == p2m_mid_missing_mfn) { 461 /* Separately check the mid mfn level */ 462 unsigned long missing_mfn; 463 unsigned long mid_mfn_mfn; 464 465 mid_mfn = alloc_p2m_page(); 466 if (!mid_mfn) 467 return false; 468 469 p2m_mid_mfn_init(mid_mfn); 470 471 missing_mfn = virt_to_mfn(p2m_mid_missing_mfn); 472 mid_mfn_mfn = virt_to_mfn(mid_mfn); 473 if (cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn) != missing_mfn) 474 free_p2m_page(mid_mfn); 475 else 476 p2m_top_mfn_p[topidx] = mid_mfn; 477 } 478 479 if (p2m_top[topidx][mididx] == p2m_identity || 480 p2m_top[topidx][mididx] == p2m_missing) { 481 /* p2m leaf page is missing */ 482 unsigned long *p2m; 483 unsigned long *p2m_orig = p2m_top[topidx][mididx]; 484 485 p2m = alloc_p2m_page(); 486 if (!p2m) 487 return false; 488 489 p2m_init(p2m); 490 491 if (cmpxchg(&mid[mididx], p2m_orig, p2m) != p2m_orig) 492 free_p2m_page(p2m); 493 else 494 mid_mfn[mididx] = virt_to_mfn(p2m); 495 } 496 497 return true; 498 } 499 500 static bool __init __early_alloc_p2m(unsigned long pfn) 501 { 502 unsigned topidx, mididx, idx; 503 504 topidx = p2m_top_index(pfn); 505 mididx = p2m_mid_index(pfn); 506 idx = p2m_index(pfn); 507 508 /* Pfff.. No boundary cross-over, lets get out. */ 509 if (!idx) 510 return false; 511 512 WARN(p2m_top[topidx][mididx] == p2m_identity, 513 "P2M[%d][%d] == IDENTITY, should be MISSING (or alloced)!\n", 514 topidx, mididx); 515 516 /* 517 * Could be done by xen_build_dynamic_phys_to_machine.. 518 */ 519 if (p2m_top[topidx][mididx] != p2m_missing) 520 return false; 521 522 /* Boundary cross-over for the edges: */ 523 if (idx) { 524 unsigned long *p2m = extend_brk(PAGE_SIZE, PAGE_SIZE); 525 unsigned long *mid_mfn_p; 526 527 p2m_init(p2m); 528 529 p2m_top[topidx][mididx] = p2m; 530 531 /* For save/restore we need to MFN of the P2M saved */ 532 533 mid_mfn_p = p2m_top_mfn_p[topidx]; 534 WARN(mid_mfn_p[mididx] != virt_to_mfn(p2m_missing), 535 "P2M_TOP_P[%d][%d] != MFN of p2m_missing!\n", 536 topidx, mididx); 537 mid_mfn_p[mididx] = virt_to_mfn(p2m); 538 539 } 540 return idx != 0; 541 } 542 unsigned long __init set_phys_range_identity(unsigned long pfn_s, 543 unsigned long pfn_e) 544 { 545 unsigned long pfn; 546 547 if (unlikely(pfn_s >= MAX_P2M_PFN || pfn_e >= MAX_P2M_PFN)) 548 return 0; 549 550 if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) 551 return pfn_e - pfn_s; 552 553 if (pfn_s > pfn_e) 554 return 0; 555 556 for (pfn = (pfn_s & ~(P2M_MID_PER_PAGE * P2M_PER_PAGE - 1)); 557 pfn < ALIGN(pfn_e, (P2M_MID_PER_PAGE * P2M_PER_PAGE)); 558 pfn += P2M_MID_PER_PAGE * P2M_PER_PAGE) 559 { 560 unsigned topidx = p2m_top_index(pfn); 561 unsigned long *mid_mfn_p; 562 unsigned long **mid; 563 564 mid = p2m_top[topidx]; 565 mid_mfn_p = p2m_top_mfn_p[topidx]; 566 if (mid == p2m_mid_missing) { 567 mid = extend_brk(PAGE_SIZE, PAGE_SIZE); 568 569 p2m_mid_init(mid); 570 571 p2m_top[topidx] = mid; 572 573 BUG_ON(mid_mfn_p != p2m_mid_missing_mfn); 574 } 575 /* And the save/restore P2M tables.. */ 576 if (mid_mfn_p == p2m_mid_missing_mfn) { 577 mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE); 578 p2m_mid_mfn_init(mid_mfn_p); 579 580 p2m_top_mfn_p[topidx] = mid_mfn_p; 581 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p); 582 /* Note: we don't set mid_mfn_p[midix] here, 583 * look in __early_alloc_p2m */ 584 } 585 } 586 587 __early_alloc_p2m(pfn_s); 588 __early_alloc_p2m(pfn_e); 589 590 for (pfn = pfn_s; pfn < pfn_e; pfn++) 591 if (!__set_phys_to_machine(pfn, IDENTITY_FRAME(pfn))) 592 break; 593 594 if (!WARN((pfn - pfn_s) != (pfn_e - pfn_s), 595 "Identity mapping failed. We are %ld short of 1-1 mappings!\n", 596 (pfn_e - pfn_s) - (pfn - pfn_s))) 597 printk(KERN_DEBUG "1-1 mapping on %lx->%lx\n", pfn_s, pfn); 598 599 return pfn - pfn_s; 600 } 601 602 /* Try to install p2m mapping; fail if intermediate bits missing */ 603 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn) 604 { 605 unsigned topidx, mididx, idx; 606 607 if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) { 608 BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY); 609 return true; 610 } 611 if (unlikely(pfn >= MAX_P2M_PFN)) { 612 BUG_ON(mfn != INVALID_P2M_ENTRY); 613 return true; 614 } 615 616 topidx = p2m_top_index(pfn); 617 mididx = p2m_mid_index(pfn); 618 idx = p2m_index(pfn); 619 620 /* For sparse holes were the p2m leaf has real PFN along with 621 * PCI holes, stick in the PFN as the MFN value. 622 */ 623 if (mfn != INVALID_P2M_ENTRY && (mfn & IDENTITY_FRAME_BIT)) { 624 if (p2m_top[topidx][mididx] == p2m_identity) 625 return true; 626 627 /* Swap over from MISSING to IDENTITY if needed. */ 628 if (p2m_top[topidx][mididx] == p2m_missing) { 629 WARN_ON(cmpxchg(&p2m_top[topidx][mididx], p2m_missing, 630 p2m_identity) != p2m_missing); 631 return true; 632 } 633 } 634 635 if (p2m_top[topidx][mididx] == p2m_missing) 636 return mfn == INVALID_P2M_ENTRY; 637 638 p2m_top[topidx][mididx][idx] = mfn; 639 640 return true; 641 } 642 643 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn) 644 { 645 if (unlikely(!__set_phys_to_machine(pfn, mfn))) { 646 if (!alloc_p2m(pfn)) 647 return false; 648 649 if (!__set_phys_to_machine(pfn, mfn)) 650 return false; 651 } 652 653 return true; 654 } 655 656 #define M2P_OVERRIDE_HASH_SHIFT 10 657 #define M2P_OVERRIDE_HASH (1 << M2P_OVERRIDE_HASH_SHIFT) 658 659 static RESERVE_BRK_ARRAY(struct list_head, m2p_overrides, M2P_OVERRIDE_HASH); 660 static DEFINE_SPINLOCK(m2p_override_lock); 661 662 static void __init m2p_override_init(void) 663 { 664 unsigned i; 665 666 m2p_overrides = extend_brk(sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH, 667 sizeof(unsigned long)); 668 669 for (i = 0; i < M2P_OVERRIDE_HASH; i++) 670 INIT_LIST_HEAD(&m2p_overrides[i]); 671 } 672 673 static unsigned long mfn_hash(unsigned long mfn) 674 { 675 return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT); 676 } 677 678 /* Add an MFN override for a particular page */ 679 int m2p_add_override(unsigned long mfn, struct page *page, bool clear_pte) 680 { 681 unsigned long flags; 682 unsigned long pfn; 683 unsigned long uninitialized_var(address); 684 unsigned level; 685 pte_t *ptep = NULL; 686 687 pfn = page_to_pfn(page); 688 if (!PageHighMem(page)) { 689 address = (unsigned long)__va(pfn << PAGE_SHIFT); 690 ptep = lookup_address(address, &level); 691 if (WARN(ptep == NULL || level != PG_LEVEL_4K, 692 "m2p_add_override: pfn %lx not mapped", pfn)) 693 return -EINVAL; 694 } 695 696 page->private = mfn; 697 page->index = pfn_to_mfn(pfn); 698 699 if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) 700 return -ENOMEM; 701 702 if (clear_pte && !PageHighMem(page)) 703 /* Just zap old mapping for now */ 704 pte_clear(&init_mm, address, ptep); 705 spin_lock_irqsave(&m2p_override_lock, flags); 706 list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]); 707 spin_unlock_irqrestore(&m2p_override_lock, flags); 708 709 return 0; 710 } 711 EXPORT_SYMBOL_GPL(m2p_add_override); 712 int m2p_remove_override(struct page *page, bool clear_pte) 713 { 714 unsigned long flags; 715 unsigned long mfn; 716 unsigned long pfn; 717 unsigned long uninitialized_var(address); 718 unsigned level; 719 pte_t *ptep = NULL; 720 721 pfn = page_to_pfn(page); 722 mfn = get_phys_to_machine(pfn); 723 if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) 724 return -EINVAL; 725 726 if (!PageHighMem(page)) { 727 address = (unsigned long)__va(pfn << PAGE_SHIFT); 728 ptep = lookup_address(address, &level); 729 730 if (WARN(ptep == NULL || level != PG_LEVEL_4K, 731 "m2p_remove_override: pfn %lx not mapped", pfn)) 732 return -EINVAL; 733 } 734 735 spin_lock_irqsave(&m2p_override_lock, flags); 736 list_del(&page->lru); 737 spin_unlock_irqrestore(&m2p_override_lock, flags); 738 set_phys_to_machine(pfn, page->index); 739 740 if (clear_pte && !PageHighMem(page)) 741 set_pte_at(&init_mm, address, ptep, 742 pfn_pte(pfn, PAGE_KERNEL)); 743 /* No tlb flush necessary because the caller already 744 * left the pte unmapped. */ 745 746 return 0; 747 } 748 EXPORT_SYMBOL_GPL(m2p_remove_override); 749 750 struct page *m2p_find_override(unsigned long mfn) 751 { 752 unsigned long flags; 753 struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)]; 754 struct page *p, *ret; 755 756 ret = NULL; 757 758 spin_lock_irqsave(&m2p_override_lock, flags); 759 760 list_for_each_entry(p, bucket, lru) { 761 if (p->private == mfn) { 762 ret = p; 763 break; 764 } 765 } 766 767 spin_unlock_irqrestore(&m2p_override_lock, flags); 768 769 return ret; 770 } 771 772 unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn) 773 { 774 struct page *p = m2p_find_override(mfn); 775 unsigned long ret = pfn; 776 777 if (p) 778 ret = page_to_pfn(p); 779 780 return ret; 781 } 782 EXPORT_SYMBOL_GPL(m2p_find_override_pfn); 783 784 #ifdef CONFIG_XEN_DEBUG_FS 785 786 int p2m_dump_show(struct seq_file *m, void *v) 787 { 788 static const char * const level_name[] = { "top", "middle", 789 "entry", "abnormal" }; 790 static const char * const type_name[] = { "identity", "missing", 791 "pfn", "abnormal"}; 792 #define TYPE_IDENTITY 0 793 #define TYPE_MISSING 1 794 #define TYPE_PFN 2 795 #define TYPE_UNKNOWN 3 796 unsigned long pfn, prev_pfn_type = 0, prev_pfn_level = 0; 797 unsigned int uninitialized_var(prev_level); 798 unsigned int uninitialized_var(prev_type); 799 800 if (!p2m_top) 801 return 0; 802 803 for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn++) { 804 unsigned topidx = p2m_top_index(pfn); 805 unsigned mididx = p2m_mid_index(pfn); 806 unsigned idx = p2m_index(pfn); 807 unsigned lvl, type; 808 809 lvl = 4; 810 type = TYPE_UNKNOWN; 811 if (p2m_top[topidx] == p2m_mid_missing) { 812 lvl = 0; type = TYPE_MISSING; 813 } else if (p2m_top[topidx] == NULL) { 814 lvl = 0; type = TYPE_UNKNOWN; 815 } else if (p2m_top[topidx][mididx] == NULL) { 816 lvl = 1; type = TYPE_UNKNOWN; 817 } else if (p2m_top[topidx][mididx] == p2m_identity) { 818 lvl = 1; type = TYPE_IDENTITY; 819 } else if (p2m_top[topidx][mididx] == p2m_missing) { 820 lvl = 1; type = TYPE_MISSING; 821 } else if (p2m_top[topidx][mididx][idx] == 0) { 822 lvl = 2; type = TYPE_UNKNOWN; 823 } else if (p2m_top[topidx][mididx][idx] == IDENTITY_FRAME(pfn)) { 824 lvl = 2; type = TYPE_IDENTITY; 825 } else if (p2m_top[topidx][mididx][idx] == INVALID_P2M_ENTRY) { 826 lvl = 2; type = TYPE_MISSING; 827 } else if (p2m_top[topidx][mididx][idx] == pfn) { 828 lvl = 2; type = TYPE_PFN; 829 } else if (p2m_top[topidx][mididx][idx] != pfn) { 830 lvl = 2; type = TYPE_PFN; 831 } 832 if (pfn == 0) { 833 prev_level = lvl; 834 prev_type = type; 835 } 836 if (pfn == MAX_DOMAIN_PAGES-1) { 837 lvl = 3; 838 type = TYPE_UNKNOWN; 839 } 840 if (prev_type != type) { 841 seq_printf(m, " [0x%lx->0x%lx] %s\n", 842 prev_pfn_type, pfn, type_name[prev_type]); 843 prev_pfn_type = pfn; 844 prev_type = type; 845 } 846 if (prev_level != lvl) { 847 seq_printf(m, " [0x%lx->0x%lx] level %s\n", 848 prev_pfn_level, pfn, level_name[prev_level]); 849 prev_pfn_level = pfn; 850 prev_level = lvl; 851 } 852 } 853 return 0; 854 #undef TYPE_IDENTITY 855 #undef TYPE_MISSING 856 #undef TYPE_PFN 857 #undef TYPE_UNKNOWN 858 } 859 #endif 860