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