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_MEMORY_HOTPLUG_LIMIT 102 #define P2M_LIMIT CONFIG_XEN_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 void p2m_top_mfn_init(unsigned long *top) 138 { 139 unsigned i; 140 141 for (i = 0; i < P2M_TOP_PER_PAGE; i++) 142 top[i] = virt_to_mfn(p2m_mid_missing_mfn); 143 } 144 145 static void p2m_top_mfn_p_init(unsigned long **top) 146 { 147 unsigned i; 148 149 for (i = 0; i < P2M_TOP_PER_PAGE; i++) 150 top[i] = p2m_mid_missing_mfn; 151 } 152 153 static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf) 154 { 155 unsigned i; 156 157 for (i = 0; i < P2M_MID_PER_PAGE; i++) 158 mid[i] = virt_to_mfn(leaf); 159 } 160 161 static void p2m_init(unsigned long *p2m) 162 { 163 unsigned i; 164 165 for (i = 0; i < P2M_PER_PAGE; i++) 166 p2m[i] = INVALID_P2M_ENTRY; 167 } 168 169 static void p2m_init_identity(unsigned long *p2m, unsigned long pfn) 170 { 171 unsigned i; 172 173 for (i = 0; i < P2M_PER_PAGE; i++) 174 p2m[i] = IDENTITY_FRAME(pfn + i); 175 } 176 177 static void * __ref alloc_p2m_page(void) 178 { 179 if (unlikely(!slab_is_available())) { 180 void *ptr = memblock_alloc(PAGE_SIZE, PAGE_SIZE); 181 182 if (!ptr) 183 panic("%s: Failed to allocate %lu bytes align=0x%lx\n", 184 __func__, PAGE_SIZE, PAGE_SIZE); 185 186 return ptr; 187 } 188 189 return (void *)__get_free_page(GFP_KERNEL); 190 } 191 192 static void __ref free_p2m_page(void *p) 193 { 194 if (unlikely(!slab_is_available())) { 195 memblock_free(p, PAGE_SIZE); 196 return; 197 } 198 199 free_page((unsigned long)p); 200 } 201 202 /* 203 * Build the parallel p2m_top_mfn and p2m_mid_mfn structures 204 * 205 * This is called both at boot time, and after resuming from suspend: 206 * - At boot time we're called rather early, and must use alloc_bootmem*() 207 * to allocate memory. 208 * 209 * - After resume we're called from within stop_machine, but the mfn 210 * tree should already be completely allocated. 211 */ 212 void __ref xen_build_mfn_list_list(void) 213 { 214 unsigned long pfn, mfn; 215 pte_t *ptep; 216 unsigned int level, topidx, mididx; 217 unsigned long *mid_mfn_p; 218 219 if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS) 220 return; 221 222 /* Pre-initialize p2m_top_mfn to be completely missing */ 223 if (p2m_top_mfn == NULL) { 224 p2m_mid_missing_mfn = alloc_p2m_page(); 225 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing); 226 227 p2m_top_mfn_p = alloc_p2m_page(); 228 p2m_top_mfn_p_init(p2m_top_mfn_p); 229 230 p2m_top_mfn = alloc_p2m_page(); 231 p2m_top_mfn_init(p2m_top_mfn); 232 } else { 233 /* Reinitialise, mfn's all change after migration */ 234 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing); 235 } 236 237 for (pfn = 0; pfn < xen_max_p2m_pfn && pfn < MAX_P2M_PFN; 238 pfn += P2M_PER_PAGE) { 239 topidx = p2m_top_index(pfn); 240 mididx = p2m_mid_index(pfn); 241 242 mid_mfn_p = p2m_top_mfn_p[topidx]; 243 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), 244 &level); 245 BUG_ON(!ptep || level != PG_LEVEL_4K); 246 mfn = pte_mfn(*ptep); 247 ptep = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1)); 248 249 /* Don't bother allocating any mfn mid levels if 250 * they're just missing, just update the stored mfn, 251 * since all could have changed over a migrate. 252 */ 253 if (ptep == p2m_missing_pte || ptep == p2m_identity_pte) { 254 BUG_ON(mididx); 255 BUG_ON(mid_mfn_p != p2m_mid_missing_mfn); 256 p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn); 257 pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE; 258 continue; 259 } 260 261 if (mid_mfn_p == p2m_mid_missing_mfn) { 262 mid_mfn_p = alloc_p2m_page(); 263 p2m_mid_mfn_init(mid_mfn_p, p2m_missing); 264 265 p2m_top_mfn_p[topidx] = mid_mfn_p; 266 } 267 268 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p); 269 mid_mfn_p[mididx] = mfn; 270 } 271 } 272 273 void xen_setup_mfn_list_list(void) 274 { 275 BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info); 276 277 if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS) 278 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = ~0UL; 279 else 280 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = 281 virt_to_mfn(p2m_top_mfn); 282 HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn; 283 HYPERVISOR_shared_info->arch.p2m_generation = 0; 284 HYPERVISOR_shared_info->arch.p2m_vaddr = (unsigned long)xen_p2m_addr; 285 HYPERVISOR_shared_info->arch.p2m_cr3 = 286 xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir)); 287 } 288 289 /* Set up p2m_top to point to the domain-builder provided p2m pages */ 290 void __init xen_build_dynamic_phys_to_machine(void) 291 { 292 unsigned long pfn; 293 294 xen_p2m_addr = (unsigned long *)xen_start_info->mfn_list; 295 xen_p2m_size = ALIGN(xen_start_info->nr_pages, P2M_PER_PAGE); 296 297 for (pfn = xen_start_info->nr_pages; pfn < xen_p2m_size; pfn++) 298 xen_p2m_addr[pfn] = INVALID_P2M_ENTRY; 299 300 xen_max_p2m_pfn = xen_p2m_size; 301 } 302 303 #define P2M_TYPE_IDENTITY 0 304 #define P2M_TYPE_MISSING 1 305 #define P2M_TYPE_PFN 2 306 #define P2M_TYPE_UNKNOWN 3 307 308 static int xen_p2m_elem_type(unsigned long pfn) 309 { 310 unsigned long mfn; 311 312 if (pfn >= xen_p2m_size) 313 return P2M_TYPE_IDENTITY; 314 315 mfn = xen_p2m_addr[pfn]; 316 317 if (mfn == INVALID_P2M_ENTRY) 318 return P2M_TYPE_MISSING; 319 320 if (mfn & IDENTITY_FRAME_BIT) 321 return P2M_TYPE_IDENTITY; 322 323 return P2M_TYPE_PFN; 324 } 325 326 static void __init xen_rebuild_p2m_list(unsigned long *p2m) 327 { 328 unsigned int i, chunk; 329 unsigned long pfn; 330 unsigned long *mfns; 331 pte_t *ptep; 332 pmd_t *pmdp; 333 int type; 334 335 p2m_missing = alloc_p2m_page(); 336 p2m_init(p2m_missing); 337 p2m_identity = alloc_p2m_page(); 338 p2m_init(p2m_identity); 339 340 p2m_missing_pte = alloc_p2m_page(); 341 paravirt_alloc_pte(&init_mm, __pa(p2m_missing_pte) >> PAGE_SHIFT); 342 p2m_identity_pte = alloc_p2m_page(); 343 paravirt_alloc_pte(&init_mm, __pa(p2m_identity_pte) >> PAGE_SHIFT); 344 for (i = 0; i < PTRS_PER_PTE; i++) { 345 set_pte(p2m_missing_pte + i, 346 pfn_pte(PFN_DOWN(__pa(p2m_missing)), PAGE_KERNEL_RO)); 347 set_pte(p2m_identity_pte + i, 348 pfn_pte(PFN_DOWN(__pa(p2m_identity)), PAGE_KERNEL_RO)); 349 } 350 351 for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += chunk) { 352 /* 353 * Try to map missing/identity PMDs or p2m-pages if possible. 354 * We have to respect the structure of the mfn_list_list 355 * which will be built just afterwards. 356 * Chunk size to test is one p2m page if we are in the middle 357 * of a mfn_list_list mid page and the complete mid page area 358 * if we are at index 0 of the mid page. Please note that a 359 * mid page might cover more than one PMD, e.g. on 32 bit PAE 360 * kernels. 361 */ 362 chunk = (pfn & (P2M_PER_PAGE * P2M_MID_PER_PAGE - 1)) ? 363 P2M_PER_PAGE : P2M_PER_PAGE * P2M_MID_PER_PAGE; 364 365 type = xen_p2m_elem_type(pfn); 366 i = 0; 367 if (type != P2M_TYPE_PFN) 368 for (i = 1; i < chunk; i++) 369 if (xen_p2m_elem_type(pfn + i) != type) 370 break; 371 if (i < chunk) 372 /* Reset to minimal chunk size. */ 373 chunk = P2M_PER_PAGE; 374 375 if (type == P2M_TYPE_PFN || i < chunk) { 376 /* Use initial p2m page contents. */ 377 mfns = alloc_p2m_page(); 378 copy_page(mfns, xen_p2m_addr + pfn); 379 ptep = populate_extra_pte((unsigned long)(p2m + pfn)); 380 set_pte(ptep, 381 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL)); 382 continue; 383 } 384 385 if (chunk == P2M_PER_PAGE) { 386 /* Map complete missing or identity p2m-page. */ 387 mfns = (type == P2M_TYPE_MISSING) ? 388 p2m_missing : p2m_identity; 389 ptep = populate_extra_pte((unsigned long)(p2m + pfn)); 390 set_pte(ptep, 391 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL_RO)); 392 continue; 393 } 394 395 /* Complete missing or identity PMD(s) can be mapped. */ 396 ptep = (type == P2M_TYPE_MISSING) ? 397 p2m_missing_pte : p2m_identity_pte; 398 for (i = 0; i < PMDS_PER_MID_PAGE; i++) { 399 pmdp = populate_extra_pmd( 400 (unsigned long)(p2m + pfn) + i * PMD_SIZE); 401 set_pmd(pmdp, __pmd(__pa(ptep) | _KERNPG_TABLE)); 402 } 403 } 404 } 405 406 void __init xen_vmalloc_p2m_tree(void) 407 { 408 static struct vm_struct vm; 409 unsigned long p2m_limit; 410 411 xen_p2m_last_pfn = xen_max_p2m_pfn; 412 413 p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE; 414 vm.flags = VM_ALLOC; 415 vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit), 416 PMD_SIZE * PMDS_PER_MID_PAGE); 417 vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE); 418 pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size); 419 420 xen_max_p2m_pfn = vm.size / sizeof(unsigned long); 421 422 xen_rebuild_p2m_list(vm.addr); 423 424 xen_p2m_addr = vm.addr; 425 xen_p2m_size = xen_max_p2m_pfn; 426 427 xen_inv_extra_mem(); 428 } 429 430 unsigned long get_phys_to_machine(unsigned long pfn) 431 { 432 pte_t *ptep; 433 unsigned int level; 434 435 if (unlikely(pfn >= xen_p2m_size)) { 436 if (pfn < xen_max_p2m_pfn) 437 return xen_chk_extra_mem(pfn); 438 439 return IDENTITY_FRAME(pfn); 440 } 441 442 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level); 443 BUG_ON(!ptep || level != PG_LEVEL_4K); 444 445 /* 446 * The INVALID_P2M_ENTRY is filled in both p2m_*identity 447 * and in p2m_*missing, so returning the INVALID_P2M_ENTRY 448 * would be wrong. 449 */ 450 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity))) 451 return IDENTITY_FRAME(pfn); 452 453 return xen_p2m_addr[pfn]; 454 } 455 EXPORT_SYMBOL_GPL(get_phys_to_machine); 456 457 /* 458 * Allocate new pmd(s). It is checked whether the old pmd is still in place. 459 * If not, nothing is changed. This is okay as the only reason for allocating 460 * a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual 461 * pmd. 462 */ 463 static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg) 464 { 465 pte_t *ptechk; 466 pte_t *pte_newpg[PMDS_PER_MID_PAGE]; 467 pmd_t *pmdp; 468 unsigned int level; 469 unsigned long flags; 470 unsigned long vaddr; 471 int i; 472 473 /* Do all allocations first to bail out in error case. */ 474 for (i = 0; i < PMDS_PER_MID_PAGE; i++) { 475 pte_newpg[i] = alloc_p2m_page(); 476 if (!pte_newpg[i]) { 477 for (i--; i >= 0; i--) 478 free_p2m_page(pte_newpg[i]); 479 480 return NULL; 481 } 482 } 483 484 vaddr = addr & ~(PMD_SIZE * PMDS_PER_MID_PAGE - 1); 485 486 for (i = 0; i < PMDS_PER_MID_PAGE; i++) { 487 copy_page(pte_newpg[i], pte_pg); 488 paravirt_alloc_pte(&init_mm, __pa(pte_newpg[i]) >> PAGE_SHIFT); 489 490 pmdp = lookup_pmd_address(vaddr); 491 BUG_ON(!pmdp); 492 493 spin_lock_irqsave(&p2m_update_lock, flags); 494 495 ptechk = lookup_address(vaddr, &level); 496 if (ptechk == pte_pg) { 497 HYPERVISOR_shared_info->arch.p2m_generation++; 498 wmb(); /* Tools are synchronizing via p2m_generation. */ 499 set_pmd(pmdp, 500 __pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE)); 501 wmb(); /* Tools are synchronizing via p2m_generation. */ 502 HYPERVISOR_shared_info->arch.p2m_generation++; 503 pte_newpg[i] = NULL; 504 } 505 506 spin_unlock_irqrestore(&p2m_update_lock, flags); 507 508 if (pte_newpg[i]) { 509 paravirt_release_pte(__pa(pte_newpg[i]) >> PAGE_SHIFT); 510 free_p2m_page(pte_newpg[i]); 511 } 512 513 vaddr += PMD_SIZE; 514 } 515 516 return lookup_address(addr, &level); 517 } 518 519 /* 520 * Fully allocate the p2m structure for a given pfn. We need to check 521 * that both the top and mid levels are allocated, and make sure the 522 * parallel mfn tree is kept in sync. We may race with other cpus, so 523 * the new pages are installed with cmpxchg; if we lose the race then 524 * simply free the page we allocated and use the one that's there. 525 */ 526 int xen_alloc_p2m_entry(unsigned long pfn) 527 { 528 unsigned topidx; 529 unsigned long *top_mfn_p, *mid_mfn; 530 pte_t *ptep, *pte_pg; 531 unsigned int level; 532 unsigned long flags; 533 unsigned long addr = (unsigned long)(xen_p2m_addr + pfn); 534 unsigned long p2m_pfn; 535 536 ptep = lookup_address(addr, &level); 537 BUG_ON(!ptep || level != PG_LEVEL_4K); 538 pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1)); 539 540 if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) { 541 /* PMD level is missing, allocate a new one */ 542 ptep = alloc_p2m_pmd(addr, pte_pg); 543 if (!ptep) 544 return -ENOMEM; 545 } 546 547 if (p2m_top_mfn && pfn < MAX_P2M_PFN) { 548 topidx = p2m_top_index(pfn); 549 top_mfn_p = &p2m_top_mfn[topidx]; 550 mid_mfn = READ_ONCE(p2m_top_mfn_p[topidx]); 551 552 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p); 553 554 if (mid_mfn == p2m_mid_missing_mfn) { 555 /* Separately check the mid mfn level */ 556 unsigned long missing_mfn; 557 unsigned long mid_mfn_mfn; 558 559 mid_mfn = alloc_p2m_page(); 560 if (!mid_mfn) 561 return -ENOMEM; 562 563 p2m_mid_mfn_init(mid_mfn, p2m_missing); 564 565 missing_mfn = virt_to_mfn(p2m_mid_missing_mfn); 566 mid_mfn_mfn = virt_to_mfn(mid_mfn); 567 /* try_cmpxchg() updates missing_mfn on failure. */ 568 if (try_cmpxchg(top_mfn_p, &missing_mfn, mid_mfn_mfn)) { 569 p2m_top_mfn_p[topidx] = mid_mfn; 570 } else { 571 free_p2m_page(mid_mfn); 572 mid_mfn = mfn_to_virt(missing_mfn); 573 } 574 } 575 } else { 576 mid_mfn = NULL; 577 } 578 579 p2m_pfn = pte_pfn(READ_ONCE(*ptep)); 580 if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) || 581 p2m_pfn == PFN_DOWN(__pa(p2m_missing))) { 582 /* p2m leaf page is missing */ 583 unsigned long *p2m; 584 585 p2m = alloc_p2m_page(); 586 if (!p2m) 587 return -ENOMEM; 588 589 if (p2m_pfn == PFN_DOWN(__pa(p2m_missing))) 590 p2m_init(p2m); 591 else 592 p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1)); 593 594 spin_lock_irqsave(&p2m_update_lock, flags); 595 596 if (pte_pfn(*ptep) == p2m_pfn) { 597 HYPERVISOR_shared_info->arch.p2m_generation++; 598 wmb(); /* Tools are synchronizing via p2m_generation. */ 599 set_pte(ptep, 600 pfn_pte(PFN_DOWN(__pa(p2m)), PAGE_KERNEL)); 601 wmb(); /* Tools are synchronizing via p2m_generation. */ 602 HYPERVISOR_shared_info->arch.p2m_generation++; 603 if (mid_mfn) 604 mid_mfn[p2m_mid_index(pfn)] = virt_to_mfn(p2m); 605 p2m = NULL; 606 } 607 608 spin_unlock_irqrestore(&p2m_update_lock, flags); 609 610 if (p2m) 611 free_p2m_page(p2m); 612 } 613 614 /* Expanded the p2m? */ 615 if (pfn >= xen_p2m_last_pfn) { 616 xen_p2m_last_pfn = ALIGN(pfn + 1, P2M_PER_PAGE); 617 HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn; 618 } 619 620 return 0; 621 } 622 EXPORT_SYMBOL(xen_alloc_p2m_entry); 623 624 unsigned long __init set_phys_range_identity(unsigned long pfn_s, 625 unsigned long pfn_e) 626 { 627 unsigned long pfn; 628 629 if (unlikely(pfn_s >= xen_p2m_size)) 630 return 0; 631 632 if (pfn_s > pfn_e) 633 return 0; 634 635 if (pfn_e > xen_p2m_size) 636 pfn_e = xen_p2m_size; 637 638 for (pfn = pfn_s; pfn < pfn_e; pfn++) 639 xen_p2m_addr[pfn] = IDENTITY_FRAME(pfn); 640 641 return pfn - pfn_s; 642 } 643 644 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn) 645 { 646 pte_t *ptep; 647 unsigned int level; 648 649 /* Only invalid entries allowed above the highest p2m covered frame. */ 650 if (unlikely(pfn >= xen_p2m_size)) 651 return mfn == INVALID_P2M_ENTRY; 652 653 /* 654 * The interface requires atomic updates on p2m elements. 655 * xen_safe_write_ulong() is using an atomic store via asm(). 656 */ 657 if (likely(!xen_safe_write_ulong(xen_p2m_addr + pfn, mfn))) 658 return true; 659 660 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level); 661 BUG_ON(!ptep || level != PG_LEVEL_4K); 662 663 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_missing))) 664 return mfn == INVALID_P2M_ENTRY; 665 666 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity))) 667 return mfn == IDENTITY_FRAME(pfn); 668 669 return false; 670 } 671 672 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn) 673 { 674 if (unlikely(!__set_phys_to_machine(pfn, mfn))) { 675 int ret; 676 677 ret = xen_alloc_p2m_entry(pfn); 678 if (ret < 0) 679 return false; 680 681 return __set_phys_to_machine(pfn, mfn); 682 } 683 684 return true; 685 } 686 687 int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops, 688 struct gnttab_map_grant_ref *kmap_ops, 689 struct page **pages, unsigned int count) 690 { 691 int i, ret = 0; 692 pte_t *pte; 693 694 if (xen_feature(XENFEAT_auto_translated_physmap)) 695 return 0; 696 697 if (kmap_ops) { 698 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, 699 kmap_ops, count); 700 if (ret) 701 goto out; 702 } 703 704 for (i = 0; i < count; i++) { 705 unsigned long mfn, pfn; 706 struct gnttab_unmap_grant_ref unmap[2]; 707 int rc; 708 709 /* Do not add to override if the map failed. */ 710 if (map_ops[i].status != GNTST_okay || 711 (kmap_ops && kmap_ops[i].status != GNTST_okay)) 712 continue; 713 714 if (map_ops[i].flags & GNTMAP_contains_pte) { 715 pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) + 716 (map_ops[i].host_addr & ~PAGE_MASK)); 717 mfn = pte_mfn(*pte); 718 } else { 719 mfn = PFN_DOWN(map_ops[i].dev_bus_addr); 720 } 721 pfn = page_to_pfn(pages[i]); 722 723 WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned"); 724 725 if (likely(set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) 726 continue; 727 728 /* 729 * Signal an error for this slot. This in turn requires 730 * immediate unmapping. 731 */ 732 map_ops[i].status = GNTST_general_error; 733 unmap[0].host_addr = map_ops[i].host_addr, 734 unmap[0].handle = map_ops[i].handle; 735 map_ops[i].handle = INVALID_GRANT_HANDLE; 736 if (map_ops[i].flags & GNTMAP_device_map) 737 unmap[0].dev_bus_addr = map_ops[i].dev_bus_addr; 738 else 739 unmap[0].dev_bus_addr = 0; 740 741 if (kmap_ops) { 742 kmap_ops[i].status = GNTST_general_error; 743 unmap[1].host_addr = kmap_ops[i].host_addr, 744 unmap[1].handle = kmap_ops[i].handle; 745 kmap_ops[i].handle = INVALID_GRANT_HANDLE; 746 if (kmap_ops[i].flags & GNTMAP_device_map) 747 unmap[1].dev_bus_addr = kmap_ops[i].dev_bus_addr; 748 else 749 unmap[1].dev_bus_addr = 0; 750 } 751 752 /* 753 * Pre-populate both status fields, to be recognizable in 754 * the log message below. 755 */ 756 unmap[0].status = 1; 757 unmap[1].status = 1; 758 759 rc = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, 760 unmap, 1 + !!kmap_ops); 761 if (rc || unmap[0].status != GNTST_okay || 762 unmap[1].status != GNTST_okay) 763 pr_err_once("gnttab unmap failed: rc=%d st0=%d st1=%d\n", 764 rc, unmap[0].status, unmap[1].status); 765 } 766 767 out: 768 return ret; 769 } 770 771 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops, 772 struct gnttab_unmap_grant_ref *kunmap_ops, 773 struct page **pages, unsigned int count) 774 { 775 int i, ret = 0; 776 777 if (xen_feature(XENFEAT_auto_translated_physmap)) 778 return 0; 779 780 for (i = 0; i < count; i++) { 781 unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i])); 782 unsigned long pfn = page_to_pfn(pages[i]); 783 784 if (mfn != INVALID_P2M_ENTRY && (mfn & FOREIGN_FRAME_BIT)) 785 set_phys_to_machine(pfn, INVALID_P2M_ENTRY); 786 else 787 ret = -EINVAL; 788 } 789 if (kunmap_ops) 790 ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, 791 kunmap_ops, count) ?: ret; 792 793 return ret; 794 } 795 796 #ifdef CONFIG_XEN_DEBUG_FS 797 #include <linux/debugfs.h> 798 #include "debugfs.h" 799 static int p2m_dump_show(struct seq_file *m, void *v) 800 { 801 static const char * const type_name[] = { 802 [P2M_TYPE_IDENTITY] = "identity", 803 [P2M_TYPE_MISSING] = "missing", 804 [P2M_TYPE_PFN] = "pfn", 805 [P2M_TYPE_UNKNOWN] = "abnormal"}; 806 unsigned long pfn, first_pfn; 807 int type, prev_type; 808 809 prev_type = xen_p2m_elem_type(0); 810 first_pfn = 0; 811 812 for (pfn = 0; pfn < xen_p2m_size; pfn++) { 813 type = xen_p2m_elem_type(pfn); 814 if (type != prev_type) { 815 seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn, 816 type_name[prev_type]); 817 prev_type = type; 818 first_pfn = pfn; 819 } 820 } 821 seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn, 822 type_name[prev_type]); 823 return 0; 824 } 825 826 DEFINE_SHOW_ATTRIBUTE(p2m_dump); 827 828 static struct dentry *d_mmu_debug; 829 830 static int __init xen_p2m_debugfs(void) 831 { 832 struct dentry *d_xen = xen_init_debugfs(); 833 834 d_mmu_debug = debugfs_create_dir("mmu", d_xen); 835 836 debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops); 837 return 0; 838 } 839 fs_initcall(xen_p2m_debugfs); 840 #endif /* CONFIG_XEN_DEBUG_FS */ 841