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 "xen-ops.h" 85 86 #define P2M_MID_PER_PAGE (PAGE_SIZE / sizeof(unsigned long *)) 87 #define P2M_TOP_PER_PAGE (PAGE_SIZE / sizeof(unsigned long **)) 88 89 #define MAX_P2M_PFN (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE) 90 91 #define PMDS_PER_MID_PAGE (P2M_MID_PER_PAGE / PTRS_PER_PTE) 92 93 unsigned long *xen_p2m_addr __read_mostly; 94 EXPORT_SYMBOL_GPL(xen_p2m_addr); 95 unsigned long xen_p2m_size __read_mostly; 96 EXPORT_SYMBOL_GPL(xen_p2m_size); 97 unsigned long xen_max_p2m_pfn __read_mostly; 98 EXPORT_SYMBOL_GPL(xen_max_p2m_pfn); 99 100 #ifdef CONFIG_XEN_MEMORY_HOTPLUG_LIMIT 101 #define P2M_LIMIT CONFIG_XEN_MEMORY_HOTPLUG_LIMIT 102 #else 103 #define P2M_LIMIT 0 104 #endif 105 106 static DEFINE_SPINLOCK(p2m_update_lock); 107 108 static unsigned long *p2m_mid_missing_mfn; 109 static unsigned long *p2m_top_mfn; 110 static unsigned long **p2m_top_mfn_p; 111 static unsigned long *p2m_missing; 112 static unsigned long *p2m_identity; 113 static pte_t *p2m_missing_pte; 114 static pte_t *p2m_identity_pte; 115 116 /* 117 * Hint at last populated PFN. 118 * 119 * Used to set HYPERVISOR_shared_info->arch.max_pfn so the toolstack 120 * can avoid scanning the whole P2M (which may be sized to account for 121 * hotplugged memory). 122 */ 123 static unsigned long xen_p2m_last_pfn; 124 125 static inline unsigned p2m_top_index(unsigned long pfn) 126 { 127 BUG_ON(pfn >= MAX_P2M_PFN); 128 return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE); 129 } 130 131 static inline unsigned p2m_mid_index(unsigned long pfn) 132 { 133 return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE; 134 } 135 136 static void p2m_top_mfn_init(unsigned long *top) 137 { 138 unsigned i; 139 140 for (i = 0; i < P2M_TOP_PER_PAGE; i++) 141 top[i] = virt_to_mfn(p2m_mid_missing_mfn); 142 } 143 144 static void p2m_top_mfn_p_init(unsigned long **top) 145 { 146 unsigned i; 147 148 for (i = 0; i < P2M_TOP_PER_PAGE; i++) 149 top[i] = p2m_mid_missing_mfn; 150 } 151 152 static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf) 153 { 154 unsigned i; 155 156 for (i = 0; i < P2M_MID_PER_PAGE; i++) 157 mid[i] = virt_to_mfn(leaf); 158 } 159 160 static void p2m_init(unsigned long *p2m) 161 { 162 unsigned i; 163 164 for (i = 0; i < P2M_PER_PAGE; i++) 165 p2m[i] = INVALID_P2M_ENTRY; 166 } 167 168 static void p2m_init_identity(unsigned long *p2m, unsigned long pfn) 169 { 170 unsigned i; 171 172 for (i = 0; i < P2M_PER_PAGE; i++) 173 p2m[i] = IDENTITY_FRAME(pfn + i); 174 } 175 176 static void * __ref alloc_p2m_page(void) 177 { 178 if (unlikely(!slab_is_available())) { 179 void *ptr = memblock_alloc(PAGE_SIZE, PAGE_SIZE); 180 181 if (!ptr) 182 panic("%s: Failed to allocate %lu bytes align=0x%lx\n", 183 __func__, PAGE_SIZE, PAGE_SIZE); 184 185 return ptr; 186 } 187 188 return (void *)__get_free_page(GFP_KERNEL); 189 } 190 191 static void __ref free_p2m_page(void *p) 192 { 193 if (unlikely(!slab_is_available())) { 194 memblock_free(p, PAGE_SIZE); 195 return; 196 } 197 198 free_page((unsigned long)p); 199 } 200 201 /* 202 * Build the parallel p2m_top_mfn and p2m_mid_mfn structures 203 * 204 * This is called both at boot time, and after resuming from suspend: 205 * - At boot time we're called rather early, and must use alloc_bootmem*() 206 * to allocate memory. 207 * 208 * - After resume we're called from within stop_machine, but the mfn 209 * tree should already be completely allocated. 210 */ 211 void __ref xen_build_mfn_list_list(void) 212 { 213 unsigned long pfn, mfn; 214 pte_t *ptep; 215 unsigned int level, topidx, mididx; 216 unsigned long *mid_mfn_p; 217 218 if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS) 219 return; 220 221 /* Pre-initialize p2m_top_mfn to be completely missing */ 222 if (p2m_top_mfn == NULL) { 223 p2m_mid_missing_mfn = alloc_p2m_page(); 224 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing); 225 226 p2m_top_mfn_p = alloc_p2m_page(); 227 p2m_top_mfn_p_init(p2m_top_mfn_p); 228 229 p2m_top_mfn = alloc_p2m_page(); 230 p2m_top_mfn_init(p2m_top_mfn); 231 } else { 232 /* Reinitialise, mfn's all change after migration */ 233 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing); 234 } 235 236 for (pfn = 0; pfn < xen_max_p2m_pfn && pfn < MAX_P2M_PFN; 237 pfn += P2M_PER_PAGE) { 238 topidx = p2m_top_index(pfn); 239 mididx = p2m_mid_index(pfn); 240 241 mid_mfn_p = p2m_top_mfn_p[topidx]; 242 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), 243 &level); 244 BUG_ON(!ptep || level != PG_LEVEL_4K); 245 mfn = pte_mfn(*ptep); 246 ptep = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1)); 247 248 /* Don't bother allocating any mfn mid levels if 249 * they're just missing, just update the stored mfn, 250 * since all could have changed over a migrate. 251 */ 252 if (ptep == p2m_missing_pte || ptep == p2m_identity_pte) { 253 BUG_ON(mididx); 254 BUG_ON(mid_mfn_p != p2m_mid_missing_mfn); 255 p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn); 256 pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE; 257 continue; 258 } 259 260 if (mid_mfn_p == p2m_mid_missing_mfn) { 261 mid_mfn_p = alloc_p2m_page(); 262 p2m_mid_mfn_init(mid_mfn_p, p2m_missing); 263 264 p2m_top_mfn_p[topidx] = mid_mfn_p; 265 } 266 267 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p); 268 mid_mfn_p[mididx] = mfn; 269 } 270 } 271 272 void xen_setup_mfn_list_list(void) 273 { 274 BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info); 275 276 if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS) 277 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = ~0UL; 278 else 279 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = 280 virt_to_mfn(p2m_top_mfn); 281 HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn; 282 HYPERVISOR_shared_info->arch.p2m_generation = 0; 283 HYPERVISOR_shared_info->arch.p2m_vaddr = (unsigned long)xen_p2m_addr; 284 HYPERVISOR_shared_info->arch.p2m_cr3 = 285 xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir)); 286 } 287 288 /* Set up p2m_top to point to the domain-builder provided p2m pages */ 289 void __init xen_build_dynamic_phys_to_machine(void) 290 { 291 unsigned long pfn; 292 293 xen_p2m_addr = (unsigned long *)xen_start_info->mfn_list; 294 xen_p2m_size = ALIGN(xen_start_info->nr_pages, P2M_PER_PAGE); 295 296 for (pfn = xen_start_info->nr_pages; pfn < xen_p2m_size; pfn++) 297 xen_p2m_addr[pfn] = INVALID_P2M_ENTRY; 298 299 xen_max_p2m_pfn = xen_p2m_size; 300 } 301 302 #define P2M_TYPE_IDENTITY 0 303 #define P2M_TYPE_MISSING 1 304 #define P2M_TYPE_PFN 2 305 #define P2M_TYPE_UNKNOWN 3 306 307 static int xen_p2m_elem_type(unsigned long pfn) 308 { 309 unsigned long mfn; 310 311 if (pfn >= xen_p2m_size) 312 return P2M_TYPE_IDENTITY; 313 314 mfn = xen_p2m_addr[pfn]; 315 316 if (mfn == INVALID_P2M_ENTRY) 317 return P2M_TYPE_MISSING; 318 319 if (mfn & IDENTITY_FRAME_BIT) 320 return P2M_TYPE_IDENTITY; 321 322 return P2M_TYPE_PFN; 323 } 324 325 static void __init xen_rebuild_p2m_list(unsigned long *p2m) 326 { 327 unsigned int i, chunk; 328 unsigned long pfn; 329 unsigned long *mfns; 330 pte_t *ptep; 331 pmd_t *pmdp; 332 int type; 333 334 p2m_missing = alloc_p2m_page(); 335 p2m_init(p2m_missing); 336 p2m_identity = alloc_p2m_page(); 337 p2m_init(p2m_identity); 338 339 p2m_missing_pte = alloc_p2m_page(); 340 paravirt_alloc_pte(&init_mm, __pa(p2m_missing_pte) >> PAGE_SHIFT); 341 p2m_identity_pte = alloc_p2m_page(); 342 paravirt_alloc_pte(&init_mm, __pa(p2m_identity_pte) >> PAGE_SHIFT); 343 for (i = 0; i < PTRS_PER_PTE; i++) { 344 set_pte(p2m_missing_pte + i, 345 pfn_pte(PFN_DOWN(__pa(p2m_missing)), PAGE_KERNEL_RO)); 346 set_pte(p2m_identity_pte + i, 347 pfn_pte(PFN_DOWN(__pa(p2m_identity)), PAGE_KERNEL_RO)); 348 } 349 350 for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += chunk) { 351 /* 352 * Try to map missing/identity PMDs or p2m-pages if possible. 353 * We have to respect the structure of the mfn_list_list 354 * which will be built just afterwards. 355 * Chunk size to test is one p2m page if we are in the middle 356 * of a mfn_list_list mid page and the complete mid page area 357 * if we are at index 0 of the mid page. Please note that a 358 * mid page might cover more than one PMD, e.g. on 32 bit PAE 359 * kernels. 360 */ 361 chunk = (pfn & (P2M_PER_PAGE * P2M_MID_PER_PAGE - 1)) ? 362 P2M_PER_PAGE : P2M_PER_PAGE * P2M_MID_PER_PAGE; 363 364 type = xen_p2m_elem_type(pfn); 365 i = 0; 366 if (type != P2M_TYPE_PFN) 367 for (i = 1; i < chunk; i++) 368 if (xen_p2m_elem_type(pfn + i) != type) 369 break; 370 if (i < chunk) 371 /* Reset to minimal chunk size. */ 372 chunk = P2M_PER_PAGE; 373 374 if (type == P2M_TYPE_PFN || i < chunk) { 375 /* Use initial p2m page contents. */ 376 mfns = alloc_p2m_page(); 377 copy_page(mfns, xen_p2m_addr + pfn); 378 ptep = populate_extra_pte((unsigned long)(p2m + pfn)); 379 set_pte(ptep, 380 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL)); 381 continue; 382 } 383 384 if (chunk == P2M_PER_PAGE) { 385 /* Map complete missing or identity p2m-page. */ 386 mfns = (type == P2M_TYPE_MISSING) ? 387 p2m_missing : p2m_identity; 388 ptep = populate_extra_pte((unsigned long)(p2m + pfn)); 389 set_pte(ptep, 390 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL_RO)); 391 continue; 392 } 393 394 /* Complete missing or identity PMD(s) can be mapped. */ 395 ptep = (type == P2M_TYPE_MISSING) ? 396 p2m_missing_pte : p2m_identity_pte; 397 for (i = 0; i < PMDS_PER_MID_PAGE; i++) { 398 pmdp = populate_extra_pmd( 399 (unsigned long)(p2m + pfn) + i * PMD_SIZE); 400 set_pmd(pmdp, __pmd(__pa(ptep) | _KERNPG_TABLE)); 401 } 402 } 403 } 404 405 void __init xen_vmalloc_p2m_tree(void) 406 { 407 static struct vm_struct vm; 408 unsigned long p2m_limit; 409 410 xen_p2m_last_pfn = xen_max_p2m_pfn; 411 412 p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE; 413 vm.flags = VM_ALLOC; 414 vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit), 415 PMD_SIZE * PMDS_PER_MID_PAGE); 416 vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE); 417 pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size); 418 419 xen_max_p2m_pfn = vm.size / sizeof(unsigned long); 420 421 xen_rebuild_p2m_list(vm.addr); 422 423 xen_p2m_addr = vm.addr; 424 xen_p2m_size = xen_max_p2m_pfn; 425 426 xen_inv_extra_mem(); 427 } 428 429 unsigned long get_phys_to_machine(unsigned long pfn) 430 { 431 pte_t *ptep; 432 unsigned int level; 433 434 if (unlikely(pfn >= xen_p2m_size)) { 435 if (pfn < xen_max_p2m_pfn) 436 return xen_chk_extra_mem(pfn); 437 438 return IDENTITY_FRAME(pfn); 439 } 440 441 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level); 442 BUG_ON(!ptep || level != PG_LEVEL_4K); 443 444 /* 445 * The INVALID_P2M_ENTRY is filled in both p2m_*identity 446 * and in p2m_*missing, so returning the INVALID_P2M_ENTRY 447 * would be wrong. 448 */ 449 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity))) 450 return IDENTITY_FRAME(pfn); 451 452 return xen_p2m_addr[pfn]; 453 } 454 EXPORT_SYMBOL_GPL(get_phys_to_machine); 455 456 /* 457 * Allocate new pmd(s). It is checked whether the old pmd is still in place. 458 * If not, nothing is changed. This is okay as the only reason for allocating 459 * a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual 460 * pmd. 461 */ 462 static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg) 463 { 464 pte_t *ptechk; 465 pte_t *pte_newpg[PMDS_PER_MID_PAGE]; 466 pmd_t *pmdp; 467 unsigned int level; 468 unsigned long flags; 469 unsigned long vaddr; 470 int i; 471 472 /* Do all allocations first to bail out in error case. */ 473 for (i = 0; i < PMDS_PER_MID_PAGE; i++) { 474 pte_newpg[i] = alloc_p2m_page(); 475 if (!pte_newpg[i]) { 476 for (i--; i >= 0; i--) 477 free_p2m_page(pte_newpg[i]); 478 479 return NULL; 480 } 481 } 482 483 vaddr = addr & ~(PMD_SIZE * PMDS_PER_MID_PAGE - 1); 484 485 for (i = 0; i < PMDS_PER_MID_PAGE; i++) { 486 copy_page(pte_newpg[i], pte_pg); 487 paravirt_alloc_pte(&init_mm, __pa(pte_newpg[i]) >> PAGE_SHIFT); 488 489 pmdp = lookup_pmd_address(vaddr); 490 BUG_ON(!pmdp); 491 492 spin_lock_irqsave(&p2m_update_lock, flags); 493 494 ptechk = lookup_address(vaddr, &level); 495 if (ptechk == pte_pg) { 496 HYPERVISOR_shared_info->arch.p2m_generation++; 497 wmb(); /* Tools are synchronizing via p2m_generation. */ 498 set_pmd(pmdp, 499 __pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE)); 500 wmb(); /* Tools are synchronizing via p2m_generation. */ 501 HYPERVISOR_shared_info->arch.p2m_generation++; 502 pte_newpg[i] = NULL; 503 } 504 505 spin_unlock_irqrestore(&p2m_update_lock, flags); 506 507 if (pte_newpg[i]) { 508 paravirt_release_pte(__pa(pte_newpg[i]) >> PAGE_SHIFT); 509 free_p2m_page(pte_newpg[i]); 510 } 511 512 vaddr += PMD_SIZE; 513 } 514 515 return lookup_address(addr, &level); 516 } 517 518 /* 519 * Fully allocate the p2m structure for a given pfn. We need to check 520 * that both the top and mid levels are allocated, and make sure the 521 * parallel mfn tree is kept in sync. We may race with other cpus, so 522 * the new pages are installed with cmpxchg; if we lose the race then 523 * simply free the page we allocated and use the one that's there. 524 */ 525 int xen_alloc_p2m_entry(unsigned long pfn) 526 { 527 unsigned topidx; 528 unsigned long *top_mfn_p, *mid_mfn; 529 pte_t *ptep, *pte_pg; 530 unsigned int level; 531 unsigned long flags; 532 unsigned long addr = (unsigned long)(xen_p2m_addr + pfn); 533 unsigned long p2m_pfn; 534 535 ptep = lookup_address(addr, &level); 536 BUG_ON(!ptep || level != PG_LEVEL_4K); 537 pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1)); 538 539 if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) { 540 /* PMD level is missing, allocate a new one */ 541 ptep = alloc_p2m_pmd(addr, pte_pg); 542 if (!ptep) 543 return -ENOMEM; 544 } 545 546 if (p2m_top_mfn && pfn < MAX_P2M_PFN) { 547 topidx = p2m_top_index(pfn); 548 top_mfn_p = &p2m_top_mfn[topidx]; 549 mid_mfn = READ_ONCE(p2m_top_mfn_p[topidx]); 550 551 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p); 552 553 if (mid_mfn == p2m_mid_missing_mfn) { 554 /* Separately check the mid mfn level */ 555 unsigned long missing_mfn; 556 unsigned long mid_mfn_mfn; 557 558 mid_mfn = alloc_p2m_page(); 559 if (!mid_mfn) 560 return -ENOMEM; 561 562 p2m_mid_mfn_init(mid_mfn, p2m_missing); 563 564 missing_mfn = virt_to_mfn(p2m_mid_missing_mfn); 565 mid_mfn_mfn = virt_to_mfn(mid_mfn); 566 /* try_cmpxchg() updates missing_mfn on failure. */ 567 if (try_cmpxchg(top_mfn_p, &missing_mfn, mid_mfn_mfn)) { 568 p2m_top_mfn_p[topidx] = mid_mfn; 569 } else { 570 free_p2m_page(mid_mfn); 571 mid_mfn = mfn_to_virt(missing_mfn); 572 } 573 } 574 } else { 575 mid_mfn = NULL; 576 } 577 578 p2m_pfn = pte_pfn(READ_ONCE(*ptep)); 579 if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) || 580 p2m_pfn == PFN_DOWN(__pa(p2m_missing))) { 581 /* p2m leaf page is missing */ 582 unsigned long *p2m; 583 584 p2m = alloc_p2m_page(); 585 if (!p2m) 586 return -ENOMEM; 587 588 if (p2m_pfn == PFN_DOWN(__pa(p2m_missing))) 589 p2m_init(p2m); 590 else 591 p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1)); 592 593 spin_lock_irqsave(&p2m_update_lock, flags); 594 595 if (pte_pfn(*ptep) == p2m_pfn) { 596 HYPERVISOR_shared_info->arch.p2m_generation++; 597 wmb(); /* Tools are synchronizing via p2m_generation. */ 598 set_pte(ptep, 599 pfn_pte(PFN_DOWN(__pa(p2m)), PAGE_KERNEL)); 600 wmb(); /* Tools are synchronizing via p2m_generation. */ 601 HYPERVISOR_shared_info->arch.p2m_generation++; 602 if (mid_mfn) 603 mid_mfn[p2m_mid_index(pfn)] = virt_to_mfn(p2m); 604 p2m = NULL; 605 } 606 607 spin_unlock_irqrestore(&p2m_update_lock, flags); 608 609 if (p2m) 610 free_p2m_page(p2m); 611 } 612 613 /* Expanded the p2m? */ 614 if (pfn >= xen_p2m_last_pfn) { 615 xen_p2m_last_pfn = ALIGN(pfn + 1, P2M_PER_PAGE); 616 HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn; 617 } 618 619 return 0; 620 } 621 EXPORT_SYMBOL(xen_alloc_p2m_entry); 622 623 unsigned long __init set_phys_range_identity(unsigned long pfn_s, 624 unsigned long pfn_e) 625 { 626 unsigned long pfn; 627 628 if (unlikely(pfn_s >= xen_p2m_size)) 629 return 0; 630 631 if (pfn_s > pfn_e) 632 return 0; 633 634 if (pfn_e > xen_p2m_size) 635 pfn_e = xen_p2m_size; 636 637 for (pfn = pfn_s; pfn < pfn_e; pfn++) 638 xen_p2m_addr[pfn] = IDENTITY_FRAME(pfn); 639 640 return pfn - pfn_s; 641 } 642 643 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn) 644 { 645 pte_t *ptep; 646 unsigned int level; 647 648 /* Only invalid entries allowed above the highest p2m covered frame. */ 649 if (unlikely(pfn >= xen_p2m_size)) 650 return mfn == INVALID_P2M_ENTRY; 651 652 /* 653 * The interface requires atomic updates on p2m elements. 654 * xen_safe_write_ulong() is using an atomic store via asm(). 655 */ 656 if (likely(!xen_safe_write_ulong(xen_p2m_addr + pfn, mfn))) 657 return true; 658 659 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level); 660 BUG_ON(!ptep || level != PG_LEVEL_4K); 661 662 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_missing))) 663 return mfn == INVALID_P2M_ENTRY; 664 665 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity))) 666 return mfn == IDENTITY_FRAME(pfn); 667 668 return false; 669 } 670 671 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn) 672 { 673 if (unlikely(!__set_phys_to_machine(pfn, mfn))) { 674 int ret; 675 676 ret = xen_alloc_p2m_entry(pfn); 677 if (ret < 0) 678 return false; 679 680 return __set_phys_to_machine(pfn, mfn); 681 } 682 683 return true; 684 } 685 686 int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops, 687 struct gnttab_map_grant_ref *kmap_ops, 688 struct page **pages, unsigned int count) 689 { 690 int i, ret = 0; 691 pte_t *pte; 692 693 if (xen_feature(XENFEAT_auto_translated_physmap)) 694 return 0; 695 696 if (kmap_ops) { 697 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, 698 kmap_ops, count); 699 if (ret) 700 goto out; 701 } 702 703 for (i = 0; i < count; i++) { 704 unsigned long mfn, pfn; 705 struct gnttab_unmap_grant_ref unmap[2]; 706 int rc; 707 708 /* Do not add to override if the map failed. */ 709 if (map_ops[i].status != GNTST_okay || 710 (kmap_ops && kmap_ops[i].status != GNTST_okay)) 711 continue; 712 713 if (map_ops[i].flags & GNTMAP_contains_pte) { 714 pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) + 715 (map_ops[i].host_addr & ~PAGE_MASK)); 716 mfn = pte_mfn(*pte); 717 } else { 718 mfn = PFN_DOWN(map_ops[i].dev_bus_addr); 719 } 720 pfn = page_to_pfn(pages[i]); 721 722 WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned"); 723 724 if (likely(set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) 725 continue; 726 727 /* 728 * Signal an error for this slot. This in turn requires 729 * immediate unmapping. 730 */ 731 map_ops[i].status = GNTST_general_error; 732 unmap[0].host_addr = map_ops[i].host_addr; 733 unmap[0].handle = map_ops[i].handle; 734 map_ops[i].handle = INVALID_GRANT_HANDLE; 735 if (map_ops[i].flags & GNTMAP_device_map) 736 unmap[0].dev_bus_addr = map_ops[i].dev_bus_addr; 737 else 738 unmap[0].dev_bus_addr = 0; 739 740 if (kmap_ops) { 741 kmap_ops[i].status = GNTST_general_error; 742 unmap[1].host_addr = kmap_ops[i].host_addr; 743 unmap[1].handle = kmap_ops[i].handle; 744 kmap_ops[i].handle = INVALID_GRANT_HANDLE; 745 if (kmap_ops[i].flags & GNTMAP_device_map) 746 unmap[1].dev_bus_addr = kmap_ops[i].dev_bus_addr; 747 else 748 unmap[1].dev_bus_addr = 0; 749 } 750 751 /* 752 * Pre-populate both status fields, to be recognizable in 753 * the log message below. 754 */ 755 unmap[0].status = 1; 756 unmap[1].status = 1; 757 758 rc = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, 759 unmap, 1 + !!kmap_ops); 760 if (rc || unmap[0].status != GNTST_okay || 761 unmap[1].status != GNTST_okay) 762 pr_err_once("gnttab unmap failed: rc=%d st0=%d st1=%d\n", 763 rc, unmap[0].status, unmap[1].status); 764 } 765 766 out: 767 return ret; 768 } 769 770 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops, 771 struct gnttab_unmap_grant_ref *kunmap_ops, 772 struct page **pages, unsigned int count) 773 { 774 int i, ret = 0; 775 776 if (xen_feature(XENFEAT_auto_translated_physmap)) 777 return 0; 778 779 for (i = 0; i < count; i++) { 780 unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i])); 781 unsigned long pfn = page_to_pfn(pages[i]); 782 783 if (mfn != INVALID_P2M_ENTRY && (mfn & FOREIGN_FRAME_BIT)) 784 set_phys_to_machine(pfn, INVALID_P2M_ENTRY); 785 else 786 ret = -EINVAL; 787 } 788 if (kunmap_ops) 789 ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, 790 kunmap_ops, count) ?: ret; 791 792 return ret; 793 } 794 795 #ifdef CONFIG_XEN_DEBUG_FS 796 #include <linux/debugfs.h> 797 static int p2m_dump_show(struct seq_file *m, void *v) 798 { 799 static const char * const type_name[] = { 800 [P2M_TYPE_IDENTITY] = "identity", 801 [P2M_TYPE_MISSING] = "missing", 802 [P2M_TYPE_PFN] = "pfn", 803 [P2M_TYPE_UNKNOWN] = "abnormal"}; 804 unsigned long pfn, first_pfn; 805 int type, prev_type; 806 807 prev_type = xen_p2m_elem_type(0); 808 first_pfn = 0; 809 810 for (pfn = 0; pfn < xen_p2m_size; pfn++) { 811 type = xen_p2m_elem_type(pfn); 812 if (type != prev_type) { 813 seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn, 814 type_name[prev_type]); 815 prev_type = type; 816 first_pfn = pfn; 817 } 818 } 819 seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn, 820 type_name[prev_type]); 821 return 0; 822 } 823 824 DEFINE_SHOW_ATTRIBUTE(p2m_dump); 825 826 static struct dentry *d_mmu_debug; 827 828 static int __init xen_p2m_debugfs(void) 829 { 830 struct dentry *d_xen = xen_init_debugfs(); 831 832 d_mmu_debug = debugfs_create_dir("mmu", d_xen); 833 834 debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops); 835 return 0; 836 } 837 fs_initcall(xen_p2m_debugfs); 838 #endif /* CONFIG_XEN_DEBUG_FS */ 839