1 // SPDX-License-Identifier: GPL-2.0 2 3 /* 4 * Xen leaves the responsibility for maintaining p2m mappings to the 5 * guests themselves, but it must also access and update the p2m array 6 * during suspend/resume when all the pages are reallocated. 7 * 8 * The logical flat p2m table is mapped to a linear kernel memory area. 9 * For accesses by Xen a three-level tree linked via mfns only is set up to 10 * allow the address space to be sparse. 11 * 12 * Xen 13 * | 14 * p2m_top_mfn 15 * / \ 16 * p2m_mid_mfn p2m_mid_mfn 17 * / / 18 * p2m p2m p2m ... 19 * 20 * The p2m_mid_mfn pages are mapped by p2m_top_mfn_p. 21 * 22 * The p2m_top_mfn level is limited to 1 page, so the maximum representable 23 * pseudo-physical address space is: 24 * P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE pages 25 * 26 * P2M_PER_PAGE depends on the architecture, as a mfn is always 27 * unsigned long (8 bytes on 64-bit, 4 bytes on 32), leading to 28 * 512 and 1024 entries respectively. 29 * 30 * In short, these structures contain the Machine Frame Number (MFN) of the PFN. 31 * 32 * However not all entries are filled with MFNs. Specifically for all other 33 * leaf entries, or for the top root, or middle one, for which there is a void 34 * entry, we assume it is "missing". So (for example) 35 * pfn_to_mfn(0x90909090)=INVALID_P2M_ENTRY. 36 * We have a dedicated page p2m_missing with all entries being 37 * INVALID_P2M_ENTRY. This page may be referenced multiple times in the p2m 38 * list/tree in case there are multiple areas with P2M_PER_PAGE invalid pfns. 39 * 40 * We also have the possibility of setting 1-1 mappings on certain regions, so 41 * that: 42 * pfn_to_mfn(0xc0000)=0xc0000 43 * 44 * The benefit of this is, that we can assume for non-RAM regions (think 45 * PCI BARs, or ACPI spaces), we can create mappings easily because we 46 * get the PFN value to match the MFN. 47 * 48 * For this to work efficiently we have one new page p2m_identity. All entries 49 * in p2m_identity are set to INVALID_P2M_ENTRY type (Xen toolstack only 50 * recognizes that and MFNs, no other fancy value). 51 * 52 * On lookup we spot that the entry points to p2m_identity and return the 53 * identity value instead of dereferencing and returning INVALID_P2M_ENTRY. 54 * If the entry points to an allocated page, we just proceed as before and 55 * return the PFN. If the PFN has IDENTITY_FRAME_BIT set we unmask that in 56 * appropriate functions (pfn_to_mfn). 57 * 58 * The reason for having the IDENTITY_FRAME_BIT instead of just returning the 59 * PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a 60 * non-identity pfn. To protect ourselves against we elect to set (and get) the 61 * IDENTITY_FRAME_BIT on all identity mapped PFNs. 62 */ 63 64 #include <linux/init.h> 65 #include <linux/export.h> 66 #include <linux/list.h> 67 #include <linux/hash.h> 68 #include <linux/sched.h> 69 #include <linux/seq_file.h> 70 #include <linux/memblock.h> 71 #include <linux/slab.h> 72 #include <linux/vmalloc.h> 73 74 #include <asm/cache.h> 75 #include <asm/setup.h> 76 #include <linux/uaccess.h> 77 78 #include <asm/xen/page.h> 79 #include <asm/xen/hypercall.h> 80 #include <asm/xen/hypervisor.h> 81 #include <xen/balloon.h> 82 #include <xen/grant_table.h> 83 84 #include "multicalls.h" 85 #include "xen-ops.h" 86 87 #define P2M_MID_PER_PAGE (PAGE_SIZE / sizeof(unsigned long *)) 88 #define P2M_TOP_PER_PAGE (PAGE_SIZE / sizeof(unsigned long **)) 89 90 #define MAX_P2M_PFN (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE) 91 92 #define PMDS_PER_MID_PAGE (P2M_MID_PER_PAGE / PTRS_PER_PTE) 93 94 unsigned long *xen_p2m_addr __read_mostly; 95 EXPORT_SYMBOL_GPL(xen_p2m_addr); 96 unsigned long xen_p2m_size __read_mostly; 97 EXPORT_SYMBOL_GPL(xen_p2m_size); 98 unsigned long xen_max_p2m_pfn __read_mostly; 99 EXPORT_SYMBOL_GPL(xen_max_p2m_pfn); 100 101 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT 102 #define P2M_LIMIT CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT 103 #else 104 #define P2M_LIMIT 0 105 #endif 106 107 static DEFINE_SPINLOCK(p2m_update_lock); 108 109 static unsigned long *p2m_mid_missing_mfn; 110 static unsigned long *p2m_top_mfn; 111 static unsigned long **p2m_top_mfn_p; 112 static unsigned long *p2m_missing; 113 static unsigned long *p2m_identity; 114 static pte_t *p2m_missing_pte; 115 static pte_t *p2m_identity_pte; 116 117 /* 118 * Hint at last populated PFN. 119 * 120 * Used to set HYPERVISOR_shared_info->arch.max_pfn so the toolstack 121 * can avoid scanning the whole P2M (which may be sized to account for 122 * hotplugged memory). 123 */ 124 static unsigned long xen_p2m_last_pfn; 125 126 static inline unsigned p2m_top_index(unsigned long pfn) 127 { 128 BUG_ON(pfn >= MAX_P2M_PFN); 129 return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE); 130 } 131 132 static inline unsigned p2m_mid_index(unsigned long pfn) 133 { 134 return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE; 135 } 136 137 static inline unsigned p2m_index(unsigned long pfn) 138 { 139 return pfn % P2M_PER_PAGE; 140 } 141 142 static void p2m_top_mfn_init(unsigned long *top) 143 { 144 unsigned i; 145 146 for (i = 0; i < P2M_TOP_PER_PAGE; i++) 147 top[i] = virt_to_mfn(p2m_mid_missing_mfn); 148 } 149 150 static void p2m_top_mfn_p_init(unsigned long **top) 151 { 152 unsigned i; 153 154 for (i = 0; i < P2M_TOP_PER_PAGE; i++) 155 top[i] = p2m_mid_missing_mfn; 156 } 157 158 static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf) 159 { 160 unsigned i; 161 162 for (i = 0; i < P2M_MID_PER_PAGE; i++) 163 mid[i] = virt_to_mfn(leaf); 164 } 165 166 static void p2m_init(unsigned long *p2m) 167 { 168 unsigned i; 169 170 for (i = 0; i < P2M_PER_PAGE; i++) 171 p2m[i] = INVALID_P2M_ENTRY; 172 } 173 174 static void p2m_init_identity(unsigned long *p2m, unsigned long pfn) 175 { 176 unsigned i; 177 178 for (i = 0; i < P2M_PER_PAGE; i++) 179 p2m[i] = IDENTITY_FRAME(pfn + i); 180 } 181 182 static void * __ref alloc_p2m_page(void) 183 { 184 if (unlikely(!slab_is_available())) { 185 void *ptr = memblock_alloc(PAGE_SIZE, PAGE_SIZE); 186 187 if (!ptr) 188 panic("%s: Failed to allocate %lu bytes align=0x%lx\n", 189 __func__, PAGE_SIZE, PAGE_SIZE); 190 191 return ptr; 192 } 193 194 return (void *)__get_free_page(GFP_KERNEL); 195 } 196 197 static void __ref free_p2m_page(void *p) 198 { 199 if (unlikely(!slab_is_available())) { 200 memblock_free((unsigned long)p, PAGE_SIZE); 201 return; 202 } 203 204 free_page((unsigned long)p); 205 } 206 207 /* 208 * Build the parallel p2m_top_mfn and p2m_mid_mfn structures 209 * 210 * This is called both at boot time, and after resuming from suspend: 211 * - At boot time we're called rather early, and must use alloc_bootmem*() 212 * to allocate memory. 213 * 214 * - After resume we're called from within stop_machine, but the mfn 215 * tree should already be completely allocated. 216 */ 217 void __ref xen_build_mfn_list_list(void) 218 { 219 unsigned long pfn, mfn; 220 pte_t *ptep; 221 unsigned int level, topidx, mididx; 222 unsigned long *mid_mfn_p; 223 224 if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS) 225 return; 226 227 /* Pre-initialize p2m_top_mfn to be completely missing */ 228 if (p2m_top_mfn == NULL) { 229 p2m_mid_missing_mfn = alloc_p2m_page(); 230 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing); 231 232 p2m_top_mfn_p = alloc_p2m_page(); 233 p2m_top_mfn_p_init(p2m_top_mfn_p); 234 235 p2m_top_mfn = alloc_p2m_page(); 236 p2m_top_mfn_init(p2m_top_mfn); 237 } else { 238 /* Reinitialise, mfn's all change after migration */ 239 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing); 240 } 241 242 for (pfn = 0; pfn < xen_max_p2m_pfn && pfn < MAX_P2M_PFN; 243 pfn += P2M_PER_PAGE) { 244 topidx = p2m_top_index(pfn); 245 mididx = p2m_mid_index(pfn); 246 247 mid_mfn_p = p2m_top_mfn_p[topidx]; 248 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), 249 &level); 250 BUG_ON(!ptep || level != PG_LEVEL_4K); 251 mfn = pte_mfn(*ptep); 252 ptep = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1)); 253 254 /* Don't bother allocating any mfn mid levels if 255 * they're just missing, just update the stored mfn, 256 * since all could have changed over a migrate. 257 */ 258 if (ptep == p2m_missing_pte || ptep == p2m_identity_pte) { 259 BUG_ON(mididx); 260 BUG_ON(mid_mfn_p != p2m_mid_missing_mfn); 261 p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn); 262 pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE; 263 continue; 264 } 265 266 if (mid_mfn_p == p2m_mid_missing_mfn) { 267 mid_mfn_p = alloc_p2m_page(); 268 p2m_mid_mfn_init(mid_mfn_p, p2m_missing); 269 270 p2m_top_mfn_p[topidx] = mid_mfn_p; 271 } 272 273 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p); 274 mid_mfn_p[mididx] = mfn; 275 } 276 } 277 278 void xen_setup_mfn_list_list(void) 279 { 280 BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info); 281 282 if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS) 283 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = ~0UL; 284 else 285 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = 286 virt_to_mfn(p2m_top_mfn); 287 HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn; 288 HYPERVISOR_shared_info->arch.p2m_generation = 0; 289 HYPERVISOR_shared_info->arch.p2m_vaddr = (unsigned long)xen_p2m_addr; 290 HYPERVISOR_shared_info->arch.p2m_cr3 = 291 xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir)); 292 } 293 294 /* Set up p2m_top to point to the domain-builder provided p2m pages */ 295 void __init xen_build_dynamic_phys_to_machine(void) 296 { 297 unsigned long pfn; 298 299 xen_p2m_addr = (unsigned long *)xen_start_info->mfn_list; 300 xen_p2m_size = ALIGN(xen_start_info->nr_pages, P2M_PER_PAGE); 301 302 for (pfn = xen_start_info->nr_pages; pfn < xen_p2m_size; pfn++) 303 xen_p2m_addr[pfn] = INVALID_P2M_ENTRY; 304 305 xen_max_p2m_pfn = xen_p2m_size; 306 } 307 308 #define P2M_TYPE_IDENTITY 0 309 #define P2M_TYPE_MISSING 1 310 #define P2M_TYPE_PFN 2 311 #define P2M_TYPE_UNKNOWN 3 312 313 static int xen_p2m_elem_type(unsigned long pfn) 314 { 315 unsigned long mfn; 316 317 if (pfn >= xen_p2m_size) 318 return P2M_TYPE_IDENTITY; 319 320 mfn = xen_p2m_addr[pfn]; 321 322 if (mfn == INVALID_P2M_ENTRY) 323 return P2M_TYPE_MISSING; 324 325 if (mfn & IDENTITY_FRAME_BIT) 326 return P2M_TYPE_IDENTITY; 327 328 return P2M_TYPE_PFN; 329 } 330 331 static void __init xen_rebuild_p2m_list(unsigned long *p2m) 332 { 333 unsigned int i, chunk; 334 unsigned long pfn; 335 unsigned long *mfns; 336 pte_t *ptep; 337 pmd_t *pmdp; 338 int type; 339 340 p2m_missing = alloc_p2m_page(); 341 p2m_init(p2m_missing); 342 p2m_identity = alloc_p2m_page(); 343 p2m_init(p2m_identity); 344 345 p2m_missing_pte = alloc_p2m_page(); 346 paravirt_alloc_pte(&init_mm, __pa(p2m_missing_pte) >> PAGE_SHIFT); 347 p2m_identity_pte = alloc_p2m_page(); 348 paravirt_alloc_pte(&init_mm, __pa(p2m_identity_pte) >> PAGE_SHIFT); 349 for (i = 0; i < PTRS_PER_PTE; i++) { 350 set_pte(p2m_missing_pte + i, 351 pfn_pte(PFN_DOWN(__pa(p2m_missing)), PAGE_KERNEL_RO)); 352 set_pte(p2m_identity_pte + i, 353 pfn_pte(PFN_DOWN(__pa(p2m_identity)), PAGE_KERNEL_RO)); 354 } 355 356 for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += chunk) { 357 /* 358 * Try to map missing/identity PMDs or p2m-pages if possible. 359 * We have to respect the structure of the mfn_list_list 360 * which will be built just afterwards. 361 * Chunk size to test is one p2m page if we are in the middle 362 * of a mfn_list_list mid page and the complete mid page area 363 * if we are at index 0 of the mid page. Please note that a 364 * mid page might cover more than one PMD, e.g. on 32 bit PAE 365 * kernels. 366 */ 367 chunk = (pfn & (P2M_PER_PAGE * P2M_MID_PER_PAGE - 1)) ? 368 P2M_PER_PAGE : P2M_PER_PAGE * P2M_MID_PER_PAGE; 369 370 type = xen_p2m_elem_type(pfn); 371 i = 0; 372 if (type != P2M_TYPE_PFN) 373 for (i = 1; i < chunk; i++) 374 if (xen_p2m_elem_type(pfn + i) != type) 375 break; 376 if (i < chunk) 377 /* Reset to minimal chunk size. */ 378 chunk = P2M_PER_PAGE; 379 380 if (type == P2M_TYPE_PFN || i < chunk) { 381 /* Use initial p2m page contents. */ 382 #ifdef CONFIG_X86_64 383 mfns = alloc_p2m_page(); 384 copy_page(mfns, xen_p2m_addr + pfn); 385 #else 386 mfns = xen_p2m_addr + pfn; 387 #endif 388 ptep = populate_extra_pte((unsigned long)(p2m + pfn)); 389 set_pte(ptep, 390 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL)); 391 continue; 392 } 393 394 if (chunk == P2M_PER_PAGE) { 395 /* Map complete missing or identity p2m-page. */ 396 mfns = (type == P2M_TYPE_MISSING) ? 397 p2m_missing : p2m_identity; 398 ptep = populate_extra_pte((unsigned long)(p2m + pfn)); 399 set_pte(ptep, 400 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL_RO)); 401 continue; 402 } 403 404 /* Complete missing or identity PMD(s) can be mapped. */ 405 ptep = (type == P2M_TYPE_MISSING) ? 406 p2m_missing_pte : p2m_identity_pte; 407 for (i = 0; i < PMDS_PER_MID_PAGE; i++) { 408 pmdp = populate_extra_pmd( 409 (unsigned long)(p2m + pfn) + i * PMD_SIZE); 410 set_pmd(pmdp, __pmd(__pa(ptep) | _KERNPG_TABLE)); 411 } 412 } 413 } 414 415 void __init xen_vmalloc_p2m_tree(void) 416 { 417 static struct vm_struct vm; 418 unsigned long p2m_limit; 419 420 xen_p2m_last_pfn = xen_max_p2m_pfn; 421 422 p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE; 423 vm.flags = VM_ALLOC; 424 vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit), 425 PMD_SIZE * PMDS_PER_MID_PAGE); 426 vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE); 427 pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size); 428 429 xen_max_p2m_pfn = vm.size / sizeof(unsigned long); 430 431 xen_rebuild_p2m_list(vm.addr); 432 433 xen_p2m_addr = vm.addr; 434 xen_p2m_size = xen_max_p2m_pfn; 435 436 xen_inv_extra_mem(); 437 } 438 439 unsigned long get_phys_to_machine(unsigned long pfn) 440 { 441 pte_t *ptep; 442 unsigned int level; 443 444 if (unlikely(pfn >= xen_p2m_size)) { 445 if (pfn < xen_max_p2m_pfn) 446 return xen_chk_extra_mem(pfn); 447 448 return IDENTITY_FRAME(pfn); 449 } 450 451 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level); 452 BUG_ON(!ptep || level != PG_LEVEL_4K); 453 454 /* 455 * The INVALID_P2M_ENTRY is filled in both p2m_*identity 456 * and in p2m_*missing, so returning the INVALID_P2M_ENTRY 457 * would be wrong. 458 */ 459 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity))) 460 return IDENTITY_FRAME(pfn); 461 462 return xen_p2m_addr[pfn]; 463 } 464 EXPORT_SYMBOL_GPL(get_phys_to_machine); 465 466 /* 467 * Allocate new pmd(s). It is checked whether the old pmd is still in place. 468 * If not, nothing is changed. This is okay as the only reason for allocating 469 * a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual 470 * pmd. In case of PAE/x86-32 there are multiple pmds to allocate! 471 */ 472 static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg) 473 { 474 pte_t *ptechk; 475 pte_t *pte_newpg[PMDS_PER_MID_PAGE]; 476 pmd_t *pmdp; 477 unsigned int level; 478 unsigned long flags; 479 unsigned long vaddr; 480 int i; 481 482 /* Do all allocations first to bail out in error case. */ 483 for (i = 0; i < PMDS_PER_MID_PAGE; i++) { 484 pte_newpg[i] = alloc_p2m_page(); 485 if (!pte_newpg[i]) { 486 for (i--; i >= 0; i--) 487 free_p2m_page(pte_newpg[i]); 488 489 return NULL; 490 } 491 } 492 493 vaddr = addr & ~(PMD_SIZE * PMDS_PER_MID_PAGE - 1); 494 495 for (i = 0; i < PMDS_PER_MID_PAGE; i++) { 496 copy_page(pte_newpg[i], pte_pg); 497 paravirt_alloc_pte(&init_mm, __pa(pte_newpg[i]) >> PAGE_SHIFT); 498 499 pmdp = lookup_pmd_address(vaddr); 500 BUG_ON(!pmdp); 501 502 spin_lock_irqsave(&p2m_update_lock, flags); 503 504 ptechk = lookup_address(vaddr, &level); 505 if (ptechk == pte_pg) { 506 HYPERVISOR_shared_info->arch.p2m_generation++; 507 wmb(); /* Tools are synchronizing via p2m_generation. */ 508 set_pmd(pmdp, 509 __pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE)); 510 wmb(); /* Tools are synchronizing via p2m_generation. */ 511 HYPERVISOR_shared_info->arch.p2m_generation++; 512 pte_newpg[i] = NULL; 513 } 514 515 spin_unlock_irqrestore(&p2m_update_lock, flags); 516 517 if (pte_newpg[i]) { 518 paravirt_release_pte(__pa(pte_newpg[i]) >> PAGE_SHIFT); 519 free_p2m_page(pte_newpg[i]); 520 } 521 522 vaddr += PMD_SIZE; 523 } 524 525 return lookup_address(addr, &level); 526 } 527 528 /* 529 * Fully allocate the p2m structure for a given pfn. We need to check 530 * that both the top and mid levels are allocated, and make sure the 531 * parallel mfn tree is kept in sync. We may race with other cpus, so 532 * the new pages are installed with cmpxchg; if we lose the race then 533 * simply free the page we allocated and use the one that's there. 534 */ 535 int xen_alloc_p2m_entry(unsigned long pfn) 536 { 537 unsigned topidx; 538 unsigned long *top_mfn_p, *mid_mfn; 539 pte_t *ptep, *pte_pg; 540 unsigned int level; 541 unsigned long flags; 542 unsigned long addr = (unsigned long)(xen_p2m_addr + pfn); 543 unsigned long p2m_pfn; 544 545 ptep = lookup_address(addr, &level); 546 BUG_ON(!ptep || level != PG_LEVEL_4K); 547 pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1)); 548 549 if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) { 550 /* PMD level is missing, allocate a new one */ 551 ptep = alloc_p2m_pmd(addr, pte_pg); 552 if (!ptep) 553 return -ENOMEM; 554 } 555 556 if (p2m_top_mfn && pfn < MAX_P2M_PFN) { 557 topidx = p2m_top_index(pfn); 558 top_mfn_p = &p2m_top_mfn[topidx]; 559 mid_mfn = READ_ONCE(p2m_top_mfn_p[topidx]); 560 561 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p); 562 563 if (mid_mfn == p2m_mid_missing_mfn) { 564 /* Separately check the mid mfn level */ 565 unsigned long missing_mfn; 566 unsigned long mid_mfn_mfn; 567 unsigned long old_mfn; 568 569 mid_mfn = alloc_p2m_page(); 570 if (!mid_mfn) 571 return -ENOMEM; 572 573 p2m_mid_mfn_init(mid_mfn, p2m_missing); 574 575 missing_mfn = virt_to_mfn(p2m_mid_missing_mfn); 576 mid_mfn_mfn = virt_to_mfn(mid_mfn); 577 old_mfn = cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn); 578 if (old_mfn != missing_mfn) { 579 free_p2m_page(mid_mfn); 580 mid_mfn = mfn_to_virt(old_mfn); 581 } else { 582 p2m_top_mfn_p[topidx] = mid_mfn; 583 } 584 } 585 } else { 586 mid_mfn = NULL; 587 } 588 589 p2m_pfn = pte_pfn(READ_ONCE(*ptep)); 590 if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) || 591 p2m_pfn == PFN_DOWN(__pa(p2m_missing))) { 592 /* p2m leaf page is missing */ 593 unsigned long *p2m; 594 595 p2m = alloc_p2m_page(); 596 if (!p2m) 597 return -ENOMEM; 598 599 if (p2m_pfn == PFN_DOWN(__pa(p2m_missing))) 600 p2m_init(p2m); 601 else 602 p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1)); 603 604 spin_lock_irqsave(&p2m_update_lock, flags); 605 606 if (pte_pfn(*ptep) == p2m_pfn) { 607 HYPERVISOR_shared_info->arch.p2m_generation++; 608 wmb(); /* Tools are synchronizing via p2m_generation. */ 609 set_pte(ptep, 610 pfn_pte(PFN_DOWN(__pa(p2m)), PAGE_KERNEL)); 611 wmb(); /* Tools are synchronizing via p2m_generation. */ 612 HYPERVISOR_shared_info->arch.p2m_generation++; 613 if (mid_mfn) 614 mid_mfn[p2m_mid_index(pfn)] = virt_to_mfn(p2m); 615 p2m = NULL; 616 } 617 618 spin_unlock_irqrestore(&p2m_update_lock, flags); 619 620 if (p2m) 621 free_p2m_page(p2m); 622 } 623 624 /* Expanded the p2m? */ 625 if (pfn > xen_p2m_last_pfn) { 626 xen_p2m_last_pfn = pfn; 627 HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn; 628 } 629 630 return 0; 631 } 632 EXPORT_SYMBOL(xen_alloc_p2m_entry); 633 634 unsigned long __init set_phys_range_identity(unsigned long pfn_s, 635 unsigned long pfn_e) 636 { 637 unsigned long pfn; 638 639 if (unlikely(pfn_s >= xen_p2m_size)) 640 return 0; 641 642 if (pfn_s > pfn_e) 643 return 0; 644 645 if (pfn_e > xen_p2m_size) 646 pfn_e = xen_p2m_size; 647 648 for (pfn = pfn_s; pfn < pfn_e; pfn++) 649 xen_p2m_addr[pfn] = IDENTITY_FRAME(pfn); 650 651 return pfn - pfn_s; 652 } 653 654 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn) 655 { 656 pte_t *ptep; 657 unsigned int level; 658 659 if (unlikely(pfn >= xen_p2m_size)) { 660 BUG_ON(mfn != INVALID_P2M_ENTRY); 661 return true; 662 } 663 664 /* 665 * The interface requires atomic updates on p2m elements. 666 * xen_safe_write_ulong() is using an atomic store via asm(). 667 */ 668 if (likely(!xen_safe_write_ulong(xen_p2m_addr + pfn, mfn))) 669 return true; 670 671 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level); 672 BUG_ON(!ptep || level != PG_LEVEL_4K); 673 674 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_missing))) 675 return mfn == INVALID_P2M_ENTRY; 676 677 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity))) 678 return mfn == IDENTITY_FRAME(pfn); 679 680 return false; 681 } 682 683 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn) 684 { 685 if (unlikely(!__set_phys_to_machine(pfn, mfn))) { 686 int ret; 687 688 ret = xen_alloc_p2m_entry(pfn); 689 if (ret < 0) 690 return false; 691 692 return __set_phys_to_machine(pfn, mfn); 693 } 694 695 return true; 696 } 697 698 int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops, 699 struct gnttab_map_grant_ref *kmap_ops, 700 struct page **pages, unsigned int count) 701 { 702 int i, ret = 0; 703 pte_t *pte; 704 705 if (xen_feature(XENFEAT_auto_translated_physmap)) 706 return 0; 707 708 if (kmap_ops) { 709 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, 710 kmap_ops, count); 711 if (ret) 712 goto out; 713 } 714 715 for (i = 0; i < count; i++) { 716 unsigned long mfn, pfn; 717 718 /* Do not add to override if the map failed. */ 719 if (map_ops[i].status) 720 continue; 721 722 if (map_ops[i].flags & GNTMAP_contains_pte) { 723 pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) + 724 (map_ops[i].host_addr & ~PAGE_MASK)); 725 mfn = pte_mfn(*pte); 726 } else { 727 mfn = PFN_DOWN(map_ops[i].dev_bus_addr); 728 } 729 pfn = page_to_pfn(pages[i]); 730 731 WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned"); 732 733 if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) { 734 ret = -ENOMEM; 735 goto out; 736 } 737 } 738 739 out: 740 return ret; 741 } 742 EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping); 743 744 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops, 745 struct gnttab_unmap_grant_ref *kunmap_ops, 746 struct page **pages, unsigned int count) 747 { 748 int i, ret = 0; 749 750 if (xen_feature(XENFEAT_auto_translated_physmap)) 751 return 0; 752 753 for (i = 0; i < count; i++) { 754 unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i])); 755 unsigned long pfn = page_to_pfn(pages[i]); 756 757 if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) { 758 ret = -EINVAL; 759 goto out; 760 } 761 762 set_phys_to_machine(pfn, INVALID_P2M_ENTRY); 763 } 764 if (kunmap_ops) 765 ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, 766 kunmap_ops, count); 767 out: 768 return ret; 769 } 770 EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping); 771 772 #ifdef CONFIG_XEN_DEBUG_FS 773 #include <linux/debugfs.h> 774 #include "debugfs.h" 775 static int p2m_dump_show(struct seq_file *m, void *v) 776 { 777 static const char * const type_name[] = { 778 [P2M_TYPE_IDENTITY] = "identity", 779 [P2M_TYPE_MISSING] = "missing", 780 [P2M_TYPE_PFN] = "pfn", 781 [P2M_TYPE_UNKNOWN] = "abnormal"}; 782 unsigned long pfn, first_pfn; 783 int type, prev_type; 784 785 prev_type = xen_p2m_elem_type(0); 786 first_pfn = 0; 787 788 for (pfn = 0; pfn < xen_p2m_size; pfn++) { 789 type = xen_p2m_elem_type(pfn); 790 if (type != prev_type) { 791 seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn, 792 type_name[prev_type]); 793 prev_type = type; 794 first_pfn = pfn; 795 } 796 } 797 seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn, 798 type_name[prev_type]); 799 return 0; 800 } 801 802 static int p2m_dump_open(struct inode *inode, struct file *filp) 803 { 804 return single_open(filp, p2m_dump_show, NULL); 805 } 806 807 static const struct file_operations p2m_dump_fops = { 808 .open = p2m_dump_open, 809 .read = seq_read, 810 .llseek = seq_lseek, 811 .release = single_release, 812 }; 813 814 static struct dentry *d_mmu_debug; 815 816 static int __init xen_p2m_debugfs(void) 817 { 818 struct dentry *d_xen = xen_init_debugfs(); 819 820 if (d_xen == NULL) 821 return -ENOMEM; 822 823 d_mmu_debug = debugfs_create_dir("mmu", d_xen); 824 825 debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops); 826 return 0; 827 } 828 fs_initcall(xen_p2m_debugfs); 829 #endif /* CONFIG_XEN_DEBUG_FS */ 830