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 mfns = alloc_p2m_page(); 383 copy_page(mfns, xen_p2m_addr + pfn); 384 ptep = populate_extra_pte((unsigned long)(p2m + pfn)); 385 set_pte(ptep, 386 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL)); 387 continue; 388 } 389 390 if (chunk == P2M_PER_PAGE) { 391 /* Map complete missing or identity p2m-page. */ 392 mfns = (type == P2M_TYPE_MISSING) ? 393 p2m_missing : p2m_identity; 394 ptep = populate_extra_pte((unsigned long)(p2m + pfn)); 395 set_pte(ptep, 396 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL_RO)); 397 continue; 398 } 399 400 /* Complete missing or identity PMD(s) can be mapped. */ 401 ptep = (type == P2M_TYPE_MISSING) ? 402 p2m_missing_pte : p2m_identity_pte; 403 for (i = 0; i < PMDS_PER_MID_PAGE; i++) { 404 pmdp = populate_extra_pmd( 405 (unsigned long)(p2m + pfn) + i * PMD_SIZE); 406 set_pmd(pmdp, __pmd(__pa(ptep) | _KERNPG_TABLE)); 407 } 408 } 409 } 410 411 void __init xen_vmalloc_p2m_tree(void) 412 { 413 static struct vm_struct vm; 414 unsigned long p2m_limit; 415 416 xen_p2m_last_pfn = xen_max_p2m_pfn; 417 418 p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE; 419 if (!p2m_limit && IS_ENABLED(CONFIG_XEN_UNPOPULATED_ALLOC)) 420 p2m_limit = xen_start_info->nr_pages * XEN_EXTRA_MEM_RATIO; 421 422 vm.flags = VM_ALLOC; 423 vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit), 424 PMD_SIZE * PMDS_PER_MID_PAGE); 425 vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE); 426 pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size); 427 428 xen_max_p2m_pfn = vm.size / sizeof(unsigned long); 429 430 xen_rebuild_p2m_list(vm.addr); 431 432 xen_p2m_addr = vm.addr; 433 xen_p2m_size = xen_max_p2m_pfn; 434 435 xen_inv_extra_mem(); 436 } 437 438 unsigned long get_phys_to_machine(unsigned long pfn) 439 { 440 pte_t *ptep; 441 unsigned int level; 442 443 if (unlikely(pfn >= xen_p2m_size)) { 444 if (pfn < xen_max_p2m_pfn) 445 return xen_chk_extra_mem(pfn); 446 447 return IDENTITY_FRAME(pfn); 448 } 449 450 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level); 451 BUG_ON(!ptep || level != PG_LEVEL_4K); 452 453 /* 454 * The INVALID_P2M_ENTRY is filled in both p2m_*identity 455 * and in p2m_*missing, so returning the INVALID_P2M_ENTRY 456 * would be wrong. 457 */ 458 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity))) 459 return IDENTITY_FRAME(pfn); 460 461 return xen_p2m_addr[pfn]; 462 } 463 EXPORT_SYMBOL_GPL(get_phys_to_machine); 464 465 /* 466 * Allocate new pmd(s). It is checked whether the old pmd is still in place. 467 * If not, nothing is changed. This is okay as the only reason for allocating 468 * a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual 469 * pmd. 470 */ 471 static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg) 472 { 473 pte_t *ptechk; 474 pte_t *pte_newpg[PMDS_PER_MID_PAGE]; 475 pmd_t *pmdp; 476 unsigned int level; 477 unsigned long flags; 478 unsigned long vaddr; 479 int i; 480 481 /* Do all allocations first to bail out in error case. */ 482 for (i = 0; i < PMDS_PER_MID_PAGE; i++) { 483 pte_newpg[i] = alloc_p2m_page(); 484 if (!pte_newpg[i]) { 485 for (i--; i >= 0; i--) 486 free_p2m_page(pte_newpg[i]); 487 488 return NULL; 489 } 490 } 491 492 vaddr = addr & ~(PMD_SIZE * PMDS_PER_MID_PAGE - 1); 493 494 for (i = 0; i < PMDS_PER_MID_PAGE; i++) { 495 copy_page(pte_newpg[i], pte_pg); 496 paravirt_alloc_pte(&init_mm, __pa(pte_newpg[i]) >> PAGE_SHIFT); 497 498 pmdp = lookup_pmd_address(vaddr); 499 BUG_ON(!pmdp); 500 501 spin_lock_irqsave(&p2m_update_lock, flags); 502 503 ptechk = lookup_address(vaddr, &level); 504 if (ptechk == pte_pg) { 505 HYPERVISOR_shared_info->arch.p2m_generation++; 506 wmb(); /* Tools are synchronizing via p2m_generation. */ 507 set_pmd(pmdp, 508 __pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE)); 509 wmb(); /* Tools are synchronizing via p2m_generation. */ 510 HYPERVISOR_shared_info->arch.p2m_generation++; 511 pte_newpg[i] = NULL; 512 } 513 514 spin_unlock_irqrestore(&p2m_update_lock, flags); 515 516 if (pte_newpg[i]) { 517 paravirt_release_pte(__pa(pte_newpg[i]) >> PAGE_SHIFT); 518 free_p2m_page(pte_newpg[i]); 519 } 520 521 vaddr += PMD_SIZE; 522 } 523 524 return lookup_address(addr, &level); 525 } 526 527 /* 528 * Fully allocate the p2m structure for a given pfn. We need to check 529 * that both the top and mid levels are allocated, and make sure the 530 * parallel mfn tree is kept in sync. We may race with other cpus, so 531 * the new pages are installed with cmpxchg; if we lose the race then 532 * simply free the page we allocated and use the one that's there. 533 */ 534 int xen_alloc_p2m_entry(unsigned long pfn) 535 { 536 unsigned topidx; 537 unsigned long *top_mfn_p, *mid_mfn; 538 pte_t *ptep, *pte_pg; 539 unsigned int level; 540 unsigned long flags; 541 unsigned long addr = (unsigned long)(xen_p2m_addr + pfn); 542 unsigned long p2m_pfn; 543 544 ptep = lookup_address(addr, &level); 545 BUG_ON(!ptep || level != PG_LEVEL_4K); 546 pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1)); 547 548 if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) { 549 /* PMD level is missing, allocate a new one */ 550 ptep = alloc_p2m_pmd(addr, pte_pg); 551 if (!ptep) 552 return -ENOMEM; 553 } 554 555 if (p2m_top_mfn && pfn < MAX_P2M_PFN) { 556 topidx = p2m_top_index(pfn); 557 top_mfn_p = &p2m_top_mfn[topidx]; 558 mid_mfn = READ_ONCE(p2m_top_mfn_p[topidx]); 559 560 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p); 561 562 if (mid_mfn == p2m_mid_missing_mfn) { 563 /* Separately check the mid mfn level */ 564 unsigned long missing_mfn; 565 unsigned long mid_mfn_mfn; 566 unsigned long old_mfn; 567 568 mid_mfn = alloc_p2m_page(); 569 if (!mid_mfn) 570 return -ENOMEM; 571 572 p2m_mid_mfn_init(mid_mfn, p2m_missing); 573 574 missing_mfn = virt_to_mfn(p2m_mid_missing_mfn); 575 mid_mfn_mfn = virt_to_mfn(mid_mfn); 576 old_mfn = cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn); 577 if (old_mfn != missing_mfn) { 578 free_p2m_page(mid_mfn); 579 mid_mfn = mfn_to_virt(old_mfn); 580 } else { 581 p2m_top_mfn_p[topidx] = mid_mfn; 582 } 583 } 584 } else { 585 mid_mfn = NULL; 586 } 587 588 p2m_pfn = pte_pfn(READ_ONCE(*ptep)); 589 if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) || 590 p2m_pfn == PFN_DOWN(__pa(p2m_missing))) { 591 /* p2m leaf page is missing */ 592 unsigned long *p2m; 593 594 p2m = alloc_p2m_page(); 595 if (!p2m) 596 return -ENOMEM; 597 598 if (p2m_pfn == PFN_DOWN(__pa(p2m_missing))) 599 p2m_init(p2m); 600 else 601 p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1)); 602 603 spin_lock_irqsave(&p2m_update_lock, flags); 604 605 if (pte_pfn(*ptep) == p2m_pfn) { 606 HYPERVISOR_shared_info->arch.p2m_generation++; 607 wmb(); /* Tools are synchronizing via p2m_generation. */ 608 set_pte(ptep, 609 pfn_pte(PFN_DOWN(__pa(p2m)), PAGE_KERNEL)); 610 wmb(); /* Tools are synchronizing via p2m_generation. */ 611 HYPERVISOR_shared_info->arch.p2m_generation++; 612 if (mid_mfn) 613 mid_mfn[p2m_mid_index(pfn)] = virt_to_mfn(p2m); 614 p2m = NULL; 615 } 616 617 spin_unlock_irqrestore(&p2m_update_lock, flags); 618 619 if (p2m) 620 free_p2m_page(p2m); 621 } 622 623 /* Expanded the p2m? */ 624 if (pfn > xen_p2m_last_pfn) { 625 xen_p2m_last_pfn = pfn; 626 HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn; 627 } 628 629 return 0; 630 } 631 EXPORT_SYMBOL(xen_alloc_p2m_entry); 632 633 unsigned long __init set_phys_range_identity(unsigned long pfn_s, 634 unsigned long pfn_e) 635 { 636 unsigned long pfn; 637 638 if (unlikely(pfn_s >= xen_p2m_size)) 639 return 0; 640 641 if (pfn_s > pfn_e) 642 return 0; 643 644 if (pfn_e > xen_p2m_size) 645 pfn_e = xen_p2m_size; 646 647 for (pfn = pfn_s; pfn < pfn_e; pfn++) 648 xen_p2m_addr[pfn] = IDENTITY_FRAME(pfn); 649 650 return pfn - pfn_s; 651 } 652 653 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn) 654 { 655 pte_t *ptep; 656 unsigned int level; 657 658 /* Only invalid entries allowed above the highest p2m covered frame. */ 659 if (unlikely(pfn >= xen_p2m_size)) 660 return mfn == INVALID_P2M_ENTRY; 661 662 /* 663 * The interface requires atomic updates on p2m elements. 664 * xen_safe_write_ulong() is using an atomic store via asm(). 665 */ 666 if (likely(!xen_safe_write_ulong(xen_p2m_addr + pfn, mfn))) 667 return true; 668 669 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level); 670 BUG_ON(!ptep || level != PG_LEVEL_4K); 671 672 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_missing))) 673 return mfn == INVALID_P2M_ENTRY; 674 675 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity))) 676 return mfn == IDENTITY_FRAME(pfn); 677 678 return false; 679 } 680 681 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn) 682 { 683 if (unlikely(!__set_phys_to_machine(pfn, mfn))) { 684 int ret; 685 686 ret = xen_alloc_p2m_entry(pfn); 687 if (ret < 0) 688 return false; 689 690 return __set_phys_to_machine(pfn, mfn); 691 } 692 693 return true; 694 } 695 696 int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops, 697 struct gnttab_map_grant_ref *kmap_ops, 698 struct page **pages, unsigned int count) 699 { 700 int i, ret = 0; 701 pte_t *pte; 702 703 if (xen_feature(XENFEAT_auto_translated_physmap)) 704 return 0; 705 706 if (kmap_ops) { 707 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, 708 kmap_ops, count); 709 if (ret) 710 goto out; 711 } 712 713 for (i = 0; i < count; i++) { 714 unsigned long mfn, pfn; 715 struct gnttab_unmap_grant_ref unmap[2]; 716 int rc; 717 718 /* Do not add to override if the map failed. */ 719 if (map_ops[i].status != GNTST_okay || 720 (kmap_ops && kmap_ops[i].status != GNTST_okay)) 721 continue; 722 723 if (map_ops[i].flags & GNTMAP_contains_pte) { 724 pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) + 725 (map_ops[i].host_addr & ~PAGE_MASK)); 726 mfn = pte_mfn(*pte); 727 } else { 728 mfn = PFN_DOWN(map_ops[i].dev_bus_addr); 729 } 730 pfn = page_to_pfn(pages[i]); 731 732 WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned"); 733 734 if (likely(set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) 735 continue; 736 737 /* 738 * Signal an error for this slot. This in turn requires 739 * immediate unmapping. 740 */ 741 map_ops[i].status = GNTST_general_error; 742 unmap[0].host_addr = map_ops[i].host_addr, 743 unmap[0].handle = map_ops[i].handle; 744 map_ops[i].handle = ~0; 745 if (map_ops[i].flags & GNTMAP_device_map) 746 unmap[0].dev_bus_addr = map_ops[i].dev_bus_addr; 747 else 748 unmap[0].dev_bus_addr = 0; 749 750 if (kmap_ops) { 751 kmap_ops[i].status = GNTST_general_error; 752 unmap[1].host_addr = kmap_ops[i].host_addr, 753 unmap[1].handle = kmap_ops[i].handle; 754 kmap_ops[i].handle = ~0; 755 if (kmap_ops[i].flags & GNTMAP_device_map) 756 unmap[1].dev_bus_addr = kmap_ops[i].dev_bus_addr; 757 else 758 unmap[1].dev_bus_addr = 0; 759 } 760 761 /* 762 * Pre-populate both status fields, to be recognizable in 763 * the log message below. 764 */ 765 unmap[0].status = 1; 766 unmap[1].status = 1; 767 768 rc = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, 769 unmap, 1 + !!kmap_ops); 770 if (rc || unmap[0].status != GNTST_okay || 771 unmap[1].status != GNTST_okay) 772 pr_err_once("gnttab unmap failed: rc=%d st0=%d st1=%d\n", 773 rc, unmap[0].status, unmap[1].status); 774 } 775 776 out: 777 return ret; 778 } 779 EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping); 780 781 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops, 782 struct gnttab_unmap_grant_ref *kunmap_ops, 783 struct page **pages, unsigned int count) 784 { 785 int i, ret = 0; 786 787 if (xen_feature(XENFEAT_auto_translated_physmap)) 788 return 0; 789 790 for (i = 0; i < count; i++) { 791 unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i])); 792 unsigned long pfn = page_to_pfn(pages[i]); 793 794 if (mfn != INVALID_P2M_ENTRY && (mfn & FOREIGN_FRAME_BIT)) 795 set_phys_to_machine(pfn, INVALID_P2M_ENTRY); 796 else 797 ret = -EINVAL; 798 } 799 if (kunmap_ops) 800 ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, 801 kunmap_ops, count) ?: ret; 802 803 return ret; 804 } 805 EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping); 806 807 #ifdef CONFIG_XEN_DEBUG_FS 808 #include <linux/debugfs.h> 809 #include "debugfs.h" 810 static int p2m_dump_show(struct seq_file *m, void *v) 811 { 812 static const char * const type_name[] = { 813 [P2M_TYPE_IDENTITY] = "identity", 814 [P2M_TYPE_MISSING] = "missing", 815 [P2M_TYPE_PFN] = "pfn", 816 [P2M_TYPE_UNKNOWN] = "abnormal"}; 817 unsigned long pfn, first_pfn; 818 int type, prev_type; 819 820 prev_type = xen_p2m_elem_type(0); 821 first_pfn = 0; 822 823 for (pfn = 0; pfn < xen_p2m_size; pfn++) { 824 type = xen_p2m_elem_type(pfn); 825 if (type != prev_type) { 826 seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn, 827 type_name[prev_type]); 828 prev_type = type; 829 first_pfn = pfn; 830 } 831 } 832 seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn, 833 type_name[prev_type]); 834 return 0; 835 } 836 837 DEFINE_SHOW_ATTRIBUTE(p2m_dump); 838 839 static struct dentry *d_mmu_debug; 840 841 static int __init xen_p2m_debugfs(void) 842 { 843 struct dentry *d_xen = xen_init_debugfs(); 844 845 d_mmu_debug = debugfs_create_dir("mmu", d_xen); 846 847 debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops); 848 return 0; 849 } 850 fs_initcall(xen_p2m_debugfs); 851 #endif /* CONFIG_XEN_DEBUG_FS */ 852