1 /* 2 * Xen mmu operations 3 * 4 * This file contains the various mmu fetch and update operations. 5 * The most important job they must perform is the mapping between the 6 * domain's pfn and the overall machine mfns. 7 * 8 * Xen allows guests to directly update the pagetable, in a controlled 9 * fashion. In other words, the guest modifies the same pagetable 10 * that the CPU actually uses, which eliminates the overhead of having 11 * a separate shadow pagetable. 12 * 13 * In order to allow this, it falls on the guest domain to map its 14 * notion of a "physical" pfn - which is just a domain-local linear 15 * address - into a real "machine address" which the CPU's MMU can 16 * use. 17 * 18 * A pgd_t/pmd_t/pte_t will typically contain an mfn, and so can be 19 * inserted directly into the pagetable. When creating a new 20 * pte/pmd/pgd, it converts the passed pfn into an mfn. Conversely, 21 * when reading the content back with __(pgd|pmd|pte)_val, it converts 22 * the mfn back into a pfn. 23 * 24 * The other constraint is that all pages which make up a pagetable 25 * must be mapped read-only in the guest. This prevents uncontrolled 26 * guest updates to the pagetable. Xen strictly enforces this, and 27 * will disallow any pagetable update which will end up mapping a 28 * pagetable page RW, and will disallow using any writable page as a 29 * pagetable. 30 * 31 * Naively, when loading %cr3 with the base of a new pagetable, Xen 32 * would need to validate the whole pagetable before going on. 33 * Naturally, this is quite slow. The solution is to "pin" a 34 * pagetable, which enforces all the constraints on the pagetable even 35 * when it is not actively in use. This menas that Xen can be assured 36 * that it is still valid when you do load it into %cr3, and doesn't 37 * need to revalidate it. 38 * 39 * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007 40 */ 41 #include <linux/sched.h> 42 #include <linux/highmem.h> 43 #include <linux/debugfs.h> 44 #include <linux/bug.h> 45 #include <linux/vmalloc.h> 46 #include <linux/module.h> 47 #include <linux/gfp.h> 48 #include <linux/memblock.h> 49 50 #include <asm/pgtable.h> 51 #include <asm/tlbflush.h> 52 #include <asm/fixmap.h> 53 #include <asm/mmu_context.h> 54 #include <asm/setup.h> 55 #include <asm/paravirt.h> 56 #include <asm/e820.h> 57 #include <asm/linkage.h> 58 #include <asm/page.h> 59 #include <asm/init.h> 60 #include <asm/pat.h> 61 62 #include <asm/xen/hypercall.h> 63 #include <asm/xen/hypervisor.h> 64 65 #include <xen/xen.h> 66 #include <xen/page.h> 67 #include <xen/interface/xen.h> 68 #include <xen/interface/hvm/hvm_op.h> 69 #include <xen/interface/version.h> 70 #include <xen/interface/memory.h> 71 #include <xen/hvc-console.h> 72 73 #include "multicalls.h" 74 #include "mmu.h" 75 #include "debugfs.h" 76 77 #define MMU_UPDATE_HISTO 30 78 79 /* 80 * Protects atomic reservation decrease/increase against concurrent increases. 81 * Also protects non-atomic updates of current_pages and driver_pages, and 82 * balloon lists. 83 */ 84 DEFINE_SPINLOCK(xen_reservation_lock); 85 86 #ifdef CONFIG_XEN_DEBUG_FS 87 88 static struct { 89 u32 pgd_update; 90 u32 pgd_update_pinned; 91 u32 pgd_update_batched; 92 93 u32 pud_update; 94 u32 pud_update_pinned; 95 u32 pud_update_batched; 96 97 u32 pmd_update; 98 u32 pmd_update_pinned; 99 u32 pmd_update_batched; 100 101 u32 pte_update; 102 u32 pte_update_pinned; 103 u32 pte_update_batched; 104 105 u32 mmu_update; 106 u32 mmu_update_extended; 107 u32 mmu_update_histo[MMU_UPDATE_HISTO]; 108 109 u32 prot_commit; 110 u32 prot_commit_batched; 111 112 u32 set_pte_at; 113 u32 set_pte_at_batched; 114 u32 set_pte_at_pinned; 115 u32 set_pte_at_current; 116 u32 set_pte_at_kernel; 117 } mmu_stats; 118 119 static u8 zero_stats; 120 121 static inline void check_zero(void) 122 { 123 if (unlikely(zero_stats)) { 124 memset(&mmu_stats, 0, sizeof(mmu_stats)); 125 zero_stats = 0; 126 } 127 } 128 129 #define ADD_STATS(elem, val) \ 130 do { check_zero(); mmu_stats.elem += (val); } while(0) 131 132 #else /* !CONFIG_XEN_DEBUG_FS */ 133 134 #define ADD_STATS(elem, val) do { (void)(val); } while(0) 135 136 #endif /* CONFIG_XEN_DEBUG_FS */ 137 138 139 /* 140 * Identity map, in addition to plain kernel map. This needs to be 141 * large enough to allocate page table pages to allocate the rest. 142 * Each page can map 2MB. 143 */ 144 #define LEVEL1_IDENT_ENTRIES (PTRS_PER_PTE * 4) 145 static RESERVE_BRK_ARRAY(pte_t, level1_ident_pgt, LEVEL1_IDENT_ENTRIES); 146 147 #ifdef CONFIG_X86_64 148 /* l3 pud for userspace vsyscall mapping */ 149 static pud_t level3_user_vsyscall[PTRS_PER_PUD] __page_aligned_bss; 150 #endif /* CONFIG_X86_64 */ 151 152 /* 153 * Note about cr3 (pagetable base) values: 154 * 155 * xen_cr3 contains the current logical cr3 value; it contains the 156 * last set cr3. This may not be the current effective cr3, because 157 * its update may be being lazily deferred. However, a vcpu looking 158 * at its own cr3 can use this value knowing that it everything will 159 * be self-consistent. 160 * 161 * xen_current_cr3 contains the actual vcpu cr3; it is set once the 162 * hypercall to set the vcpu cr3 is complete (so it may be a little 163 * out of date, but it will never be set early). If one vcpu is 164 * looking at another vcpu's cr3 value, it should use this variable. 165 */ 166 DEFINE_PER_CPU(unsigned long, xen_cr3); /* cr3 stored as physaddr */ 167 DEFINE_PER_CPU(unsigned long, xen_current_cr3); /* actual vcpu cr3 */ 168 169 170 /* 171 * Just beyond the highest usermode address. STACK_TOP_MAX has a 172 * redzone above it, so round it up to a PGD boundary. 173 */ 174 #define USER_LIMIT ((STACK_TOP_MAX + PGDIR_SIZE - 1) & PGDIR_MASK) 175 176 unsigned long arbitrary_virt_to_mfn(void *vaddr) 177 { 178 xmaddr_t maddr = arbitrary_virt_to_machine(vaddr); 179 180 return PFN_DOWN(maddr.maddr); 181 } 182 183 xmaddr_t arbitrary_virt_to_machine(void *vaddr) 184 { 185 unsigned long address = (unsigned long)vaddr; 186 unsigned int level; 187 pte_t *pte; 188 unsigned offset; 189 190 /* 191 * if the PFN is in the linear mapped vaddr range, we can just use 192 * the (quick) virt_to_machine() p2m lookup 193 */ 194 if (virt_addr_valid(vaddr)) 195 return virt_to_machine(vaddr); 196 197 /* otherwise we have to do a (slower) full page-table walk */ 198 199 pte = lookup_address(address, &level); 200 BUG_ON(pte == NULL); 201 offset = address & ~PAGE_MASK; 202 return XMADDR(((phys_addr_t)pte_mfn(*pte) << PAGE_SHIFT) + offset); 203 } 204 EXPORT_SYMBOL_GPL(arbitrary_virt_to_machine); 205 206 void make_lowmem_page_readonly(void *vaddr) 207 { 208 pte_t *pte, ptev; 209 unsigned long address = (unsigned long)vaddr; 210 unsigned int level; 211 212 pte = lookup_address(address, &level); 213 if (pte == NULL) 214 return; /* vaddr missing */ 215 216 ptev = pte_wrprotect(*pte); 217 218 if (HYPERVISOR_update_va_mapping(address, ptev, 0)) 219 BUG(); 220 } 221 222 void make_lowmem_page_readwrite(void *vaddr) 223 { 224 pte_t *pte, ptev; 225 unsigned long address = (unsigned long)vaddr; 226 unsigned int level; 227 228 pte = lookup_address(address, &level); 229 if (pte == NULL) 230 return; /* vaddr missing */ 231 232 ptev = pte_mkwrite(*pte); 233 234 if (HYPERVISOR_update_va_mapping(address, ptev, 0)) 235 BUG(); 236 } 237 238 239 static bool xen_page_pinned(void *ptr) 240 { 241 struct page *page = virt_to_page(ptr); 242 243 return PagePinned(page); 244 } 245 246 static bool xen_iomap_pte(pte_t pte) 247 { 248 return pte_flags(pte) & _PAGE_IOMAP; 249 } 250 251 void xen_set_domain_pte(pte_t *ptep, pte_t pteval, unsigned domid) 252 { 253 struct multicall_space mcs; 254 struct mmu_update *u; 255 256 mcs = xen_mc_entry(sizeof(*u)); 257 u = mcs.args; 258 259 /* ptep might be kmapped when using 32-bit HIGHPTE */ 260 u->ptr = arbitrary_virt_to_machine(ptep).maddr; 261 u->val = pte_val_ma(pteval); 262 263 MULTI_mmu_update(mcs.mc, mcs.args, 1, NULL, domid); 264 265 xen_mc_issue(PARAVIRT_LAZY_MMU); 266 } 267 EXPORT_SYMBOL_GPL(xen_set_domain_pte); 268 269 static void xen_set_iomap_pte(pte_t *ptep, pte_t pteval) 270 { 271 xen_set_domain_pte(ptep, pteval, DOMID_IO); 272 } 273 274 static void xen_extend_mmu_update(const struct mmu_update *update) 275 { 276 struct multicall_space mcs; 277 struct mmu_update *u; 278 279 mcs = xen_mc_extend_args(__HYPERVISOR_mmu_update, sizeof(*u)); 280 281 if (mcs.mc != NULL) { 282 ADD_STATS(mmu_update_extended, 1); 283 ADD_STATS(mmu_update_histo[mcs.mc->args[1]], -1); 284 285 mcs.mc->args[1]++; 286 287 if (mcs.mc->args[1] < MMU_UPDATE_HISTO) 288 ADD_STATS(mmu_update_histo[mcs.mc->args[1]], 1); 289 else 290 ADD_STATS(mmu_update_histo[0], 1); 291 } else { 292 ADD_STATS(mmu_update, 1); 293 mcs = __xen_mc_entry(sizeof(*u)); 294 MULTI_mmu_update(mcs.mc, mcs.args, 1, NULL, DOMID_SELF); 295 ADD_STATS(mmu_update_histo[1], 1); 296 } 297 298 u = mcs.args; 299 *u = *update; 300 } 301 302 void xen_set_pmd_hyper(pmd_t *ptr, pmd_t val) 303 { 304 struct mmu_update u; 305 306 preempt_disable(); 307 308 xen_mc_batch(); 309 310 /* ptr may be ioremapped for 64-bit pagetable setup */ 311 u.ptr = arbitrary_virt_to_machine(ptr).maddr; 312 u.val = pmd_val_ma(val); 313 xen_extend_mmu_update(&u); 314 315 ADD_STATS(pmd_update_batched, paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU); 316 317 xen_mc_issue(PARAVIRT_LAZY_MMU); 318 319 preempt_enable(); 320 } 321 322 void xen_set_pmd(pmd_t *ptr, pmd_t val) 323 { 324 ADD_STATS(pmd_update, 1); 325 326 /* If page is not pinned, we can just update the entry 327 directly */ 328 if (!xen_page_pinned(ptr)) { 329 *ptr = val; 330 return; 331 } 332 333 ADD_STATS(pmd_update_pinned, 1); 334 335 xen_set_pmd_hyper(ptr, val); 336 } 337 338 /* 339 * Associate a virtual page frame with a given physical page frame 340 * and protection flags for that frame. 341 */ 342 void set_pte_mfn(unsigned long vaddr, unsigned long mfn, pgprot_t flags) 343 { 344 set_pte_vaddr(vaddr, mfn_pte(mfn, flags)); 345 } 346 347 void xen_set_pte_at(struct mm_struct *mm, unsigned long addr, 348 pte_t *ptep, pte_t pteval) 349 { 350 if (xen_iomap_pte(pteval)) { 351 xen_set_iomap_pte(ptep, pteval); 352 goto out; 353 } 354 355 ADD_STATS(set_pte_at, 1); 356 // ADD_STATS(set_pte_at_pinned, xen_page_pinned(ptep)); 357 ADD_STATS(set_pte_at_current, mm == current->mm); 358 ADD_STATS(set_pte_at_kernel, mm == &init_mm); 359 360 if (mm == current->mm || mm == &init_mm) { 361 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { 362 struct multicall_space mcs; 363 mcs = xen_mc_entry(0); 364 365 MULTI_update_va_mapping(mcs.mc, addr, pteval, 0); 366 ADD_STATS(set_pte_at_batched, 1); 367 xen_mc_issue(PARAVIRT_LAZY_MMU); 368 goto out; 369 } else 370 if (HYPERVISOR_update_va_mapping(addr, pteval, 0) == 0) 371 goto out; 372 } 373 xen_set_pte(ptep, pteval); 374 375 out: return; 376 } 377 378 pte_t xen_ptep_modify_prot_start(struct mm_struct *mm, 379 unsigned long addr, pte_t *ptep) 380 { 381 /* Just return the pte as-is. We preserve the bits on commit */ 382 return *ptep; 383 } 384 385 void xen_ptep_modify_prot_commit(struct mm_struct *mm, unsigned long addr, 386 pte_t *ptep, pte_t pte) 387 { 388 struct mmu_update u; 389 390 xen_mc_batch(); 391 392 u.ptr = arbitrary_virt_to_machine(ptep).maddr | MMU_PT_UPDATE_PRESERVE_AD; 393 u.val = pte_val_ma(pte); 394 xen_extend_mmu_update(&u); 395 396 ADD_STATS(prot_commit, 1); 397 ADD_STATS(prot_commit_batched, paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU); 398 399 xen_mc_issue(PARAVIRT_LAZY_MMU); 400 } 401 402 /* Assume pteval_t is equivalent to all the other *val_t types. */ 403 static pteval_t pte_mfn_to_pfn(pteval_t val) 404 { 405 if (val & _PAGE_PRESENT) { 406 unsigned long mfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT; 407 pteval_t flags = val & PTE_FLAGS_MASK; 408 val = ((pteval_t)mfn_to_pfn(mfn) << PAGE_SHIFT) | flags; 409 } 410 411 return val; 412 } 413 414 static pteval_t pte_pfn_to_mfn(pteval_t val) 415 { 416 if (val & _PAGE_PRESENT) { 417 unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT; 418 pteval_t flags = val & PTE_FLAGS_MASK; 419 unsigned long mfn = pfn_to_mfn(pfn); 420 421 /* 422 * If there's no mfn for the pfn, then just create an 423 * empty non-present pte. Unfortunately this loses 424 * information about the original pfn, so 425 * pte_mfn_to_pfn is asymmetric. 426 */ 427 if (unlikely(mfn == INVALID_P2M_ENTRY)) { 428 mfn = 0; 429 flags = 0; 430 } 431 432 val = ((pteval_t)mfn << PAGE_SHIFT) | flags; 433 } 434 435 return val; 436 } 437 438 static pteval_t iomap_pte(pteval_t val) 439 { 440 if (val & _PAGE_PRESENT) { 441 unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT; 442 pteval_t flags = val & PTE_FLAGS_MASK; 443 444 /* We assume the pte frame number is a MFN, so 445 just use it as-is. */ 446 val = ((pteval_t)pfn << PAGE_SHIFT) | flags; 447 } 448 449 return val; 450 } 451 452 pteval_t xen_pte_val(pte_t pte) 453 { 454 pteval_t pteval = pte.pte; 455 456 /* If this is a WC pte, convert back from Xen WC to Linux WC */ 457 if ((pteval & (_PAGE_PAT | _PAGE_PCD | _PAGE_PWT)) == _PAGE_PAT) { 458 WARN_ON(!pat_enabled); 459 pteval = (pteval & ~_PAGE_PAT) | _PAGE_PWT; 460 } 461 462 if (xen_initial_domain() && (pteval & _PAGE_IOMAP)) 463 return pteval; 464 465 return pte_mfn_to_pfn(pteval); 466 } 467 PV_CALLEE_SAVE_REGS_THUNK(xen_pte_val); 468 469 pgdval_t xen_pgd_val(pgd_t pgd) 470 { 471 return pte_mfn_to_pfn(pgd.pgd); 472 } 473 PV_CALLEE_SAVE_REGS_THUNK(xen_pgd_val); 474 475 /* 476 * Xen's PAT setup is part of its ABI, though I assume entries 6 & 7 477 * are reserved for now, to correspond to the Intel-reserved PAT 478 * types. 479 * 480 * We expect Linux's PAT set as follows: 481 * 482 * Idx PTE flags Linux Xen Default 483 * 0 WB WB WB 484 * 1 PWT WC WT WT 485 * 2 PCD UC- UC- UC- 486 * 3 PCD PWT UC UC UC 487 * 4 PAT WB WC WB 488 * 5 PAT PWT WC WP WT 489 * 6 PAT PCD UC- UC UC- 490 * 7 PAT PCD PWT UC UC UC 491 */ 492 493 void xen_set_pat(u64 pat) 494 { 495 /* We expect Linux to use a PAT setting of 496 * UC UC- WC WB (ignoring the PAT flag) */ 497 WARN_ON(pat != 0x0007010600070106ull); 498 } 499 500 pte_t xen_make_pte(pteval_t pte) 501 { 502 phys_addr_t addr = (pte & PTE_PFN_MASK); 503 504 /* If Linux is trying to set a WC pte, then map to the Xen WC. 505 * If _PAGE_PAT is set, then it probably means it is really 506 * _PAGE_PSE, so avoid fiddling with the PAT mapping and hope 507 * things work out OK... 508 * 509 * (We should never see kernel mappings with _PAGE_PSE set, 510 * but we could see hugetlbfs mappings, I think.). 511 */ 512 if (pat_enabled && !WARN_ON(pte & _PAGE_PAT)) { 513 if ((pte & (_PAGE_PCD | _PAGE_PWT)) == _PAGE_PWT) 514 pte = (pte & ~(_PAGE_PCD | _PAGE_PWT)) | _PAGE_PAT; 515 } 516 517 /* 518 * Unprivileged domains are allowed to do IOMAPpings for 519 * PCI passthrough, but not map ISA space. The ISA 520 * mappings are just dummy local mappings to keep other 521 * parts of the kernel happy. 522 */ 523 if (unlikely(pte & _PAGE_IOMAP) && 524 (xen_initial_domain() || addr >= ISA_END_ADDRESS)) { 525 pte = iomap_pte(pte); 526 } else { 527 pte &= ~_PAGE_IOMAP; 528 pte = pte_pfn_to_mfn(pte); 529 } 530 531 return native_make_pte(pte); 532 } 533 PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte); 534 535 pgd_t xen_make_pgd(pgdval_t pgd) 536 { 537 pgd = pte_pfn_to_mfn(pgd); 538 return native_make_pgd(pgd); 539 } 540 PV_CALLEE_SAVE_REGS_THUNK(xen_make_pgd); 541 542 pmdval_t xen_pmd_val(pmd_t pmd) 543 { 544 return pte_mfn_to_pfn(pmd.pmd); 545 } 546 PV_CALLEE_SAVE_REGS_THUNK(xen_pmd_val); 547 548 void xen_set_pud_hyper(pud_t *ptr, pud_t val) 549 { 550 struct mmu_update u; 551 552 preempt_disable(); 553 554 xen_mc_batch(); 555 556 /* ptr may be ioremapped for 64-bit pagetable setup */ 557 u.ptr = arbitrary_virt_to_machine(ptr).maddr; 558 u.val = pud_val_ma(val); 559 xen_extend_mmu_update(&u); 560 561 ADD_STATS(pud_update_batched, paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU); 562 563 xen_mc_issue(PARAVIRT_LAZY_MMU); 564 565 preempt_enable(); 566 } 567 568 void xen_set_pud(pud_t *ptr, pud_t val) 569 { 570 ADD_STATS(pud_update, 1); 571 572 /* If page is not pinned, we can just update the entry 573 directly */ 574 if (!xen_page_pinned(ptr)) { 575 *ptr = val; 576 return; 577 } 578 579 ADD_STATS(pud_update_pinned, 1); 580 581 xen_set_pud_hyper(ptr, val); 582 } 583 584 void xen_set_pte(pte_t *ptep, pte_t pte) 585 { 586 if (xen_iomap_pte(pte)) { 587 xen_set_iomap_pte(ptep, pte); 588 return; 589 } 590 591 ADD_STATS(pte_update, 1); 592 // ADD_STATS(pte_update_pinned, xen_page_pinned(ptep)); 593 ADD_STATS(pte_update_batched, paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU); 594 595 #ifdef CONFIG_X86_PAE 596 ptep->pte_high = pte.pte_high; 597 smp_wmb(); 598 ptep->pte_low = pte.pte_low; 599 #else 600 *ptep = pte; 601 #endif 602 } 603 604 #ifdef CONFIG_X86_PAE 605 void xen_set_pte_atomic(pte_t *ptep, pte_t pte) 606 { 607 if (xen_iomap_pte(pte)) { 608 xen_set_iomap_pte(ptep, pte); 609 return; 610 } 611 612 set_64bit((u64 *)ptep, native_pte_val(pte)); 613 } 614 615 void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) 616 { 617 ptep->pte_low = 0; 618 smp_wmb(); /* make sure low gets written first */ 619 ptep->pte_high = 0; 620 } 621 622 void xen_pmd_clear(pmd_t *pmdp) 623 { 624 set_pmd(pmdp, __pmd(0)); 625 } 626 #endif /* CONFIG_X86_PAE */ 627 628 pmd_t xen_make_pmd(pmdval_t pmd) 629 { 630 pmd = pte_pfn_to_mfn(pmd); 631 return native_make_pmd(pmd); 632 } 633 PV_CALLEE_SAVE_REGS_THUNK(xen_make_pmd); 634 635 #if PAGETABLE_LEVELS == 4 636 pudval_t xen_pud_val(pud_t pud) 637 { 638 return pte_mfn_to_pfn(pud.pud); 639 } 640 PV_CALLEE_SAVE_REGS_THUNK(xen_pud_val); 641 642 pud_t xen_make_pud(pudval_t pud) 643 { 644 pud = pte_pfn_to_mfn(pud); 645 646 return native_make_pud(pud); 647 } 648 PV_CALLEE_SAVE_REGS_THUNK(xen_make_pud); 649 650 pgd_t *xen_get_user_pgd(pgd_t *pgd) 651 { 652 pgd_t *pgd_page = (pgd_t *)(((unsigned long)pgd) & PAGE_MASK); 653 unsigned offset = pgd - pgd_page; 654 pgd_t *user_ptr = NULL; 655 656 if (offset < pgd_index(USER_LIMIT)) { 657 struct page *page = virt_to_page(pgd_page); 658 user_ptr = (pgd_t *)page->private; 659 if (user_ptr) 660 user_ptr += offset; 661 } 662 663 return user_ptr; 664 } 665 666 static void __xen_set_pgd_hyper(pgd_t *ptr, pgd_t val) 667 { 668 struct mmu_update u; 669 670 u.ptr = virt_to_machine(ptr).maddr; 671 u.val = pgd_val_ma(val); 672 xen_extend_mmu_update(&u); 673 } 674 675 /* 676 * Raw hypercall-based set_pgd, intended for in early boot before 677 * there's a page structure. This implies: 678 * 1. The only existing pagetable is the kernel's 679 * 2. It is always pinned 680 * 3. It has no user pagetable attached to it 681 */ 682 void __init xen_set_pgd_hyper(pgd_t *ptr, pgd_t val) 683 { 684 preempt_disable(); 685 686 xen_mc_batch(); 687 688 __xen_set_pgd_hyper(ptr, val); 689 690 xen_mc_issue(PARAVIRT_LAZY_MMU); 691 692 preempt_enable(); 693 } 694 695 void xen_set_pgd(pgd_t *ptr, pgd_t val) 696 { 697 pgd_t *user_ptr = xen_get_user_pgd(ptr); 698 699 ADD_STATS(pgd_update, 1); 700 701 /* If page is not pinned, we can just update the entry 702 directly */ 703 if (!xen_page_pinned(ptr)) { 704 *ptr = val; 705 if (user_ptr) { 706 WARN_ON(xen_page_pinned(user_ptr)); 707 *user_ptr = val; 708 } 709 return; 710 } 711 712 ADD_STATS(pgd_update_pinned, 1); 713 ADD_STATS(pgd_update_batched, paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU); 714 715 /* If it's pinned, then we can at least batch the kernel and 716 user updates together. */ 717 xen_mc_batch(); 718 719 __xen_set_pgd_hyper(ptr, val); 720 if (user_ptr) 721 __xen_set_pgd_hyper(user_ptr, val); 722 723 xen_mc_issue(PARAVIRT_LAZY_MMU); 724 } 725 #endif /* PAGETABLE_LEVELS == 4 */ 726 727 /* 728 * (Yet another) pagetable walker. This one is intended for pinning a 729 * pagetable. This means that it walks a pagetable and calls the 730 * callback function on each page it finds making up the page table, 731 * at every level. It walks the entire pagetable, but it only bothers 732 * pinning pte pages which are below limit. In the normal case this 733 * will be STACK_TOP_MAX, but at boot we need to pin up to 734 * FIXADDR_TOP. 735 * 736 * For 32-bit the important bit is that we don't pin beyond there, 737 * because then we start getting into Xen's ptes. 738 * 739 * For 64-bit, we must skip the Xen hole in the middle of the address 740 * space, just after the big x86-64 virtual hole. 741 */ 742 static int __xen_pgd_walk(struct mm_struct *mm, pgd_t *pgd, 743 int (*func)(struct mm_struct *mm, struct page *, 744 enum pt_level), 745 unsigned long limit) 746 { 747 int flush = 0; 748 unsigned hole_low, hole_high; 749 unsigned pgdidx_limit, pudidx_limit, pmdidx_limit; 750 unsigned pgdidx, pudidx, pmdidx; 751 752 /* The limit is the last byte to be touched */ 753 limit--; 754 BUG_ON(limit >= FIXADDR_TOP); 755 756 if (xen_feature(XENFEAT_auto_translated_physmap)) 757 return 0; 758 759 /* 760 * 64-bit has a great big hole in the middle of the address 761 * space, which contains the Xen mappings. On 32-bit these 762 * will end up making a zero-sized hole and so is a no-op. 763 */ 764 hole_low = pgd_index(USER_LIMIT); 765 hole_high = pgd_index(PAGE_OFFSET); 766 767 pgdidx_limit = pgd_index(limit); 768 #if PTRS_PER_PUD > 1 769 pudidx_limit = pud_index(limit); 770 #else 771 pudidx_limit = 0; 772 #endif 773 #if PTRS_PER_PMD > 1 774 pmdidx_limit = pmd_index(limit); 775 #else 776 pmdidx_limit = 0; 777 #endif 778 779 for (pgdidx = 0; pgdidx <= pgdidx_limit; pgdidx++) { 780 pud_t *pud; 781 782 if (pgdidx >= hole_low && pgdidx < hole_high) 783 continue; 784 785 if (!pgd_val(pgd[pgdidx])) 786 continue; 787 788 pud = pud_offset(&pgd[pgdidx], 0); 789 790 if (PTRS_PER_PUD > 1) /* not folded */ 791 flush |= (*func)(mm, virt_to_page(pud), PT_PUD); 792 793 for (pudidx = 0; pudidx < PTRS_PER_PUD; pudidx++) { 794 pmd_t *pmd; 795 796 if (pgdidx == pgdidx_limit && 797 pudidx > pudidx_limit) 798 goto out; 799 800 if (pud_none(pud[pudidx])) 801 continue; 802 803 pmd = pmd_offset(&pud[pudidx], 0); 804 805 if (PTRS_PER_PMD > 1) /* not folded */ 806 flush |= (*func)(mm, virt_to_page(pmd), PT_PMD); 807 808 for (pmdidx = 0; pmdidx < PTRS_PER_PMD; pmdidx++) { 809 struct page *pte; 810 811 if (pgdidx == pgdidx_limit && 812 pudidx == pudidx_limit && 813 pmdidx > pmdidx_limit) 814 goto out; 815 816 if (pmd_none(pmd[pmdidx])) 817 continue; 818 819 pte = pmd_page(pmd[pmdidx]); 820 flush |= (*func)(mm, pte, PT_PTE); 821 } 822 } 823 } 824 825 out: 826 /* Do the top level last, so that the callbacks can use it as 827 a cue to do final things like tlb flushes. */ 828 flush |= (*func)(mm, virt_to_page(pgd), PT_PGD); 829 830 return flush; 831 } 832 833 static int xen_pgd_walk(struct mm_struct *mm, 834 int (*func)(struct mm_struct *mm, struct page *, 835 enum pt_level), 836 unsigned long limit) 837 { 838 return __xen_pgd_walk(mm, mm->pgd, func, limit); 839 } 840 841 /* If we're using split pte locks, then take the page's lock and 842 return a pointer to it. Otherwise return NULL. */ 843 static spinlock_t *xen_pte_lock(struct page *page, struct mm_struct *mm) 844 { 845 spinlock_t *ptl = NULL; 846 847 #if USE_SPLIT_PTLOCKS 848 ptl = __pte_lockptr(page); 849 spin_lock_nest_lock(ptl, &mm->page_table_lock); 850 #endif 851 852 return ptl; 853 } 854 855 static void xen_pte_unlock(void *v) 856 { 857 spinlock_t *ptl = v; 858 spin_unlock(ptl); 859 } 860 861 static void xen_do_pin(unsigned level, unsigned long pfn) 862 { 863 struct mmuext_op *op; 864 struct multicall_space mcs; 865 866 mcs = __xen_mc_entry(sizeof(*op)); 867 op = mcs.args; 868 op->cmd = level; 869 op->arg1.mfn = pfn_to_mfn(pfn); 870 MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF); 871 } 872 873 static int xen_pin_page(struct mm_struct *mm, struct page *page, 874 enum pt_level level) 875 { 876 unsigned pgfl = TestSetPagePinned(page); 877 int flush; 878 879 if (pgfl) 880 flush = 0; /* already pinned */ 881 else if (PageHighMem(page)) 882 /* kmaps need flushing if we found an unpinned 883 highpage */ 884 flush = 1; 885 else { 886 void *pt = lowmem_page_address(page); 887 unsigned long pfn = page_to_pfn(page); 888 struct multicall_space mcs = __xen_mc_entry(0); 889 spinlock_t *ptl; 890 891 flush = 0; 892 893 /* 894 * We need to hold the pagetable lock between the time 895 * we make the pagetable RO and when we actually pin 896 * it. If we don't, then other users may come in and 897 * attempt to update the pagetable by writing it, 898 * which will fail because the memory is RO but not 899 * pinned, so Xen won't do the trap'n'emulate. 900 * 901 * If we're using split pte locks, we can't hold the 902 * entire pagetable's worth of locks during the 903 * traverse, because we may wrap the preempt count (8 904 * bits). The solution is to mark RO and pin each PTE 905 * page while holding the lock. This means the number 906 * of locks we end up holding is never more than a 907 * batch size (~32 entries, at present). 908 * 909 * If we're not using split pte locks, we needn't pin 910 * the PTE pages independently, because we're 911 * protected by the overall pagetable lock. 912 */ 913 ptl = NULL; 914 if (level == PT_PTE) 915 ptl = xen_pte_lock(page, mm); 916 917 MULTI_update_va_mapping(mcs.mc, (unsigned long)pt, 918 pfn_pte(pfn, PAGE_KERNEL_RO), 919 level == PT_PGD ? UVMF_TLB_FLUSH : 0); 920 921 if (ptl) { 922 xen_do_pin(MMUEXT_PIN_L1_TABLE, pfn); 923 924 /* Queue a deferred unlock for when this batch 925 is completed. */ 926 xen_mc_callback(xen_pte_unlock, ptl); 927 } 928 } 929 930 return flush; 931 } 932 933 /* This is called just after a mm has been created, but it has not 934 been used yet. We need to make sure that its pagetable is all 935 read-only, and can be pinned. */ 936 static void __xen_pgd_pin(struct mm_struct *mm, pgd_t *pgd) 937 { 938 xen_mc_batch(); 939 940 if (__xen_pgd_walk(mm, pgd, xen_pin_page, USER_LIMIT)) { 941 /* re-enable interrupts for flushing */ 942 xen_mc_issue(0); 943 944 kmap_flush_unused(); 945 946 xen_mc_batch(); 947 } 948 949 #ifdef CONFIG_X86_64 950 { 951 pgd_t *user_pgd = xen_get_user_pgd(pgd); 952 953 xen_do_pin(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa(pgd))); 954 955 if (user_pgd) { 956 xen_pin_page(mm, virt_to_page(user_pgd), PT_PGD); 957 xen_do_pin(MMUEXT_PIN_L4_TABLE, 958 PFN_DOWN(__pa(user_pgd))); 959 } 960 } 961 #else /* CONFIG_X86_32 */ 962 #ifdef CONFIG_X86_PAE 963 /* Need to make sure unshared kernel PMD is pinnable */ 964 xen_pin_page(mm, pgd_page(pgd[pgd_index(TASK_SIZE)]), 965 PT_PMD); 966 #endif 967 xen_do_pin(MMUEXT_PIN_L3_TABLE, PFN_DOWN(__pa(pgd))); 968 #endif /* CONFIG_X86_64 */ 969 xen_mc_issue(0); 970 } 971 972 static void xen_pgd_pin(struct mm_struct *mm) 973 { 974 __xen_pgd_pin(mm, mm->pgd); 975 } 976 977 /* 978 * On save, we need to pin all pagetables to make sure they get their 979 * mfns turned into pfns. Search the list for any unpinned pgds and pin 980 * them (unpinned pgds are not currently in use, probably because the 981 * process is under construction or destruction). 982 * 983 * Expected to be called in stop_machine() ("equivalent to taking 984 * every spinlock in the system"), so the locking doesn't really 985 * matter all that much. 986 */ 987 void xen_mm_pin_all(void) 988 { 989 struct page *page; 990 991 spin_lock(&pgd_lock); 992 993 list_for_each_entry(page, &pgd_list, lru) { 994 if (!PagePinned(page)) { 995 __xen_pgd_pin(&init_mm, (pgd_t *)page_address(page)); 996 SetPageSavePinned(page); 997 } 998 } 999 1000 spin_unlock(&pgd_lock); 1001 } 1002 1003 /* 1004 * The init_mm pagetable is really pinned as soon as its created, but 1005 * that's before we have page structures to store the bits. So do all 1006 * the book-keeping now. 1007 */ 1008 static __init int xen_mark_pinned(struct mm_struct *mm, struct page *page, 1009 enum pt_level level) 1010 { 1011 SetPagePinned(page); 1012 return 0; 1013 } 1014 1015 static void __init xen_mark_init_mm_pinned(void) 1016 { 1017 xen_pgd_walk(&init_mm, xen_mark_pinned, FIXADDR_TOP); 1018 } 1019 1020 static int xen_unpin_page(struct mm_struct *mm, struct page *page, 1021 enum pt_level level) 1022 { 1023 unsigned pgfl = TestClearPagePinned(page); 1024 1025 if (pgfl && !PageHighMem(page)) { 1026 void *pt = lowmem_page_address(page); 1027 unsigned long pfn = page_to_pfn(page); 1028 spinlock_t *ptl = NULL; 1029 struct multicall_space mcs; 1030 1031 /* 1032 * Do the converse to pin_page. If we're using split 1033 * pte locks, we must be holding the lock for while 1034 * the pte page is unpinned but still RO to prevent 1035 * concurrent updates from seeing it in this 1036 * partially-pinned state. 1037 */ 1038 if (level == PT_PTE) { 1039 ptl = xen_pte_lock(page, mm); 1040 1041 if (ptl) 1042 xen_do_pin(MMUEXT_UNPIN_TABLE, pfn); 1043 } 1044 1045 mcs = __xen_mc_entry(0); 1046 1047 MULTI_update_va_mapping(mcs.mc, (unsigned long)pt, 1048 pfn_pte(pfn, PAGE_KERNEL), 1049 level == PT_PGD ? UVMF_TLB_FLUSH : 0); 1050 1051 if (ptl) { 1052 /* unlock when batch completed */ 1053 xen_mc_callback(xen_pte_unlock, ptl); 1054 } 1055 } 1056 1057 return 0; /* never need to flush on unpin */ 1058 } 1059 1060 /* Release a pagetables pages back as normal RW */ 1061 static void __xen_pgd_unpin(struct mm_struct *mm, pgd_t *pgd) 1062 { 1063 xen_mc_batch(); 1064 1065 xen_do_pin(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd))); 1066 1067 #ifdef CONFIG_X86_64 1068 { 1069 pgd_t *user_pgd = xen_get_user_pgd(pgd); 1070 1071 if (user_pgd) { 1072 xen_do_pin(MMUEXT_UNPIN_TABLE, 1073 PFN_DOWN(__pa(user_pgd))); 1074 xen_unpin_page(mm, virt_to_page(user_pgd), PT_PGD); 1075 } 1076 } 1077 #endif 1078 1079 #ifdef CONFIG_X86_PAE 1080 /* Need to make sure unshared kernel PMD is unpinned */ 1081 xen_unpin_page(mm, pgd_page(pgd[pgd_index(TASK_SIZE)]), 1082 PT_PMD); 1083 #endif 1084 1085 __xen_pgd_walk(mm, pgd, xen_unpin_page, USER_LIMIT); 1086 1087 xen_mc_issue(0); 1088 } 1089 1090 static void xen_pgd_unpin(struct mm_struct *mm) 1091 { 1092 __xen_pgd_unpin(mm, mm->pgd); 1093 } 1094 1095 /* 1096 * On resume, undo any pinning done at save, so that the rest of the 1097 * kernel doesn't see any unexpected pinned pagetables. 1098 */ 1099 void xen_mm_unpin_all(void) 1100 { 1101 struct page *page; 1102 1103 spin_lock(&pgd_lock); 1104 1105 list_for_each_entry(page, &pgd_list, lru) { 1106 if (PageSavePinned(page)) { 1107 BUG_ON(!PagePinned(page)); 1108 __xen_pgd_unpin(&init_mm, (pgd_t *)page_address(page)); 1109 ClearPageSavePinned(page); 1110 } 1111 } 1112 1113 spin_unlock(&pgd_lock); 1114 } 1115 1116 void xen_activate_mm(struct mm_struct *prev, struct mm_struct *next) 1117 { 1118 spin_lock(&next->page_table_lock); 1119 xen_pgd_pin(next); 1120 spin_unlock(&next->page_table_lock); 1121 } 1122 1123 void xen_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm) 1124 { 1125 spin_lock(&mm->page_table_lock); 1126 xen_pgd_pin(mm); 1127 spin_unlock(&mm->page_table_lock); 1128 } 1129 1130 1131 #ifdef CONFIG_SMP 1132 /* Another cpu may still have their %cr3 pointing at the pagetable, so 1133 we need to repoint it somewhere else before we can unpin it. */ 1134 static void drop_other_mm_ref(void *info) 1135 { 1136 struct mm_struct *mm = info; 1137 struct mm_struct *active_mm; 1138 1139 active_mm = percpu_read(cpu_tlbstate.active_mm); 1140 1141 if (active_mm == mm) 1142 leave_mm(smp_processor_id()); 1143 1144 /* If this cpu still has a stale cr3 reference, then make sure 1145 it has been flushed. */ 1146 if (percpu_read(xen_current_cr3) == __pa(mm->pgd)) 1147 load_cr3(swapper_pg_dir); 1148 } 1149 1150 static void xen_drop_mm_ref(struct mm_struct *mm) 1151 { 1152 cpumask_var_t mask; 1153 unsigned cpu; 1154 1155 if (current->active_mm == mm) { 1156 if (current->mm == mm) 1157 load_cr3(swapper_pg_dir); 1158 else 1159 leave_mm(smp_processor_id()); 1160 } 1161 1162 /* Get the "official" set of cpus referring to our pagetable. */ 1163 if (!alloc_cpumask_var(&mask, GFP_ATOMIC)) { 1164 for_each_online_cpu(cpu) { 1165 if (!cpumask_test_cpu(cpu, mm_cpumask(mm)) 1166 && per_cpu(xen_current_cr3, cpu) != __pa(mm->pgd)) 1167 continue; 1168 smp_call_function_single(cpu, drop_other_mm_ref, mm, 1); 1169 } 1170 return; 1171 } 1172 cpumask_copy(mask, mm_cpumask(mm)); 1173 1174 /* It's possible that a vcpu may have a stale reference to our 1175 cr3, because its in lazy mode, and it hasn't yet flushed 1176 its set of pending hypercalls yet. In this case, we can 1177 look at its actual current cr3 value, and force it to flush 1178 if needed. */ 1179 for_each_online_cpu(cpu) { 1180 if (per_cpu(xen_current_cr3, cpu) == __pa(mm->pgd)) 1181 cpumask_set_cpu(cpu, mask); 1182 } 1183 1184 if (!cpumask_empty(mask)) 1185 smp_call_function_many(mask, drop_other_mm_ref, mm, 1); 1186 free_cpumask_var(mask); 1187 } 1188 #else 1189 static void xen_drop_mm_ref(struct mm_struct *mm) 1190 { 1191 if (current->active_mm == mm) 1192 load_cr3(swapper_pg_dir); 1193 } 1194 #endif 1195 1196 /* 1197 * While a process runs, Xen pins its pagetables, which means that the 1198 * hypervisor forces it to be read-only, and it controls all updates 1199 * to it. This means that all pagetable updates have to go via the 1200 * hypervisor, which is moderately expensive. 1201 * 1202 * Since we're pulling the pagetable down, we switch to use init_mm, 1203 * unpin old process pagetable and mark it all read-write, which 1204 * allows further operations on it to be simple memory accesses. 1205 * 1206 * The only subtle point is that another CPU may be still using the 1207 * pagetable because of lazy tlb flushing. This means we need need to 1208 * switch all CPUs off this pagetable before we can unpin it. 1209 */ 1210 void xen_exit_mmap(struct mm_struct *mm) 1211 { 1212 get_cpu(); /* make sure we don't move around */ 1213 xen_drop_mm_ref(mm); 1214 put_cpu(); 1215 1216 spin_lock(&mm->page_table_lock); 1217 1218 /* pgd may not be pinned in the error exit path of execve */ 1219 if (xen_page_pinned(mm->pgd)) 1220 xen_pgd_unpin(mm); 1221 1222 spin_unlock(&mm->page_table_lock); 1223 } 1224 1225 static __init void xen_pagetable_setup_start(pgd_t *base) 1226 { 1227 } 1228 1229 static void xen_post_allocator_init(void); 1230 1231 static __init void xen_pagetable_setup_done(pgd_t *base) 1232 { 1233 xen_setup_shared_info(); 1234 xen_post_allocator_init(); 1235 } 1236 1237 static void xen_write_cr2(unsigned long cr2) 1238 { 1239 percpu_read(xen_vcpu)->arch.cr2 = cr2; 1240 } 1241 1242 static unsigned long xen_read_cr2(void) 1243 { 1244 return percpu_read(xen_vcpu)->arch.cr2; 1245 } 1246 1247 unsigned long xen_read_cr2_direct(void) 1248 { 1249 return percpu_read(xen_vcpu_info.arch.cr2); 1250 } 1251 1252 static void xen_flush_tlb(void) 1253 { 1254 struct mmuext_op *op; 1255 struct multicall_space mcs; 1256 1257 preempt_disable(); 1258 1259 mcs = xen_mc_entry(sizeof(*op)); 1260 1261 op = mcs.args; 1262 op->cmd = MMUEXT_TLB_FLUSH_LOCAL; 1263 MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF); 1264 1265 xen_mc_issue(PARAVIRT_LAZY_MMU); 1266 1267 preempt_enable(); 1268 } 1269 1270 static void xen_flush_tlb_single(unsigned long addr) 1271 { 1272 struct mmuext_op *op; 1273 struct multicall_space mcs; 1274 1275 preempt_disable(); 1276 1277 mcs = xen_mc_entry(sizeof(*op)); 1278 op = mcs.args; 1279 op->cmd = MMUEXT_INVLPG_LOCAL; 1280 op->arg1.linear_addr = addr & PAGE_MASK; 1281 MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF); 1282 1283 xen_mc_issue(PARAVIRT_LAZY_MMU); 1284 1285 preempt_enable(); 1286 } 1287 1288 static void xen_flush_tlb_others(const struct cpumask *cpus, 1289 struct mm_struct *mm, unsigned long va) 1290 { 1291 struct { 1292 struct mmuext_op op; 1293 DECLARE_BITMAP(mask, NR_CPUS); 1294 } *args; 1295 struct multicall_space mcs; 1296 1297 if (cpumask_empty(cpus)) 1298 return; /* nothing to do */ 1299 1300 mcs = xen_mc_entry(sizeof(*args)); 1301 args = mcs.args; 1302 args->op.arg2.vcpumask = to_cpumask(args->mask); 1303 1304 /* Remove us, and any offline CPUS. */ 1305 cpumask_and(to_cpumask(args->mask), cpus, cpu_online_mask); 1306 cpumask_clear_cpu(smp_processor_id(), to_cpumask(args->mask)); 1307 1308 if (va == TLB_FLUSH_ALL) { 1309 args->op.cmd = MMUEXT_TLB_FLUSH_MULTI; 1310 } else { 1311 args->op.cmd = MMUEXT_INVLPG_MULTI; 1312 args->op.arg1.linear_addr = va; 1313 } 1314 1315 MULTI_mmuext_op(mcs.mc, &args->op, 1, NULL, DOMID_SELF); 1316 1317 xen_mc_issue(PARAVIRT_LAZY_MMU); 1318 } 1319 1320 static unsigned long xen_read_cr3(void) 1321 { 1322 return percpu_read(xen_cr3); 1323 } 1324 1325 static void set_current_cr3(void *v) 1326 { 1327 percpu_write(xen_current_cr3, (unsigned long)v); 1328 } 1329 1330 static void __xen_write_cr3(bool kernel, unsigned long cr3) 1331 { 1332 struct mmuext_op *op; 1333 struct multicall_space mcs; 1334 unsigned long mfn; 1335 1336 if (cr3) 1337 mfn = pfn_to_mfn(PFN_DOWN(cr3)); 1338 else 1339 mfn = 0; 1340 1341 WARN_ON(mfn == 0 && kernel); 1342 1343 mcs = __xen_mc_entry(sizeof(*op)); 1344 1345 op = mcs.args; 1346 op->cmd = kernel ? MMUEXT_NEW_BASEPTR : MMUEXT_NEW_USER_BASEPTR; 1347 op->arg1.mfn = mfn; 1348 1349 MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF); 1350 1351 if (kernel) { 1352 percpu_write(xen_cr3, cr3); 1353 1354 /* Update xen_current_cr3 once the batch has actually 1355 been submitted. */ 1356 xen_mc_callback(set_current_cr3, (void *)cr3); 1357 } 1358 } 1359 1360 static void xen_write_cr3(unsigned long cr3) 1361 { 1362 BUG_ON(preemptible()); 1363 1364 xen_mc_batch(); /* disables interrupts */ 1365 1366 /* Update while interrupts are disabled, so its atomic with 1367 respect to ipis */ 1368 percpu_write(xen_cr3, cr3); 1369 1370 __xen_write_cr3(true, cr3); 1371 1372 #ifdef CONFIG_X86_64 1373 { 1374 pgd_t *user_pgd = xen_get_user_pgd(__va(cr3)); 1375 if (user_pgd) 1376 __xen_write_cr3(false, __pa(user_pgd)); 1377 else 1378 __xen_write_cr3(false, 0); 1379 } 1380 #endif 1381 1382 xen_mc_issue(PARAVIRT_LAZY_CPU); /* interrupts restored */ 1383 } 1384 1385 static int xen_pgd_alloc(struct mm_struct *mm) 1386 { 1387 pgd_t *pgd = mm->pgd; 1388 int ret = 0; 1389 1390 BUG_ON(PagePinned(virt_to_page(pgd))); 1391 1392 #ifdef CONFIG_X86_64 1393 { 1394 struct page *page = virt_to_page(pgd); 1395 pgd_t *user_pgd; 1396 1397 BUG_ON(page->private != 0); 1398 1399 ret = -ENOMEM; 1400 1401 user_pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO); 1402 page->private = (unsigned long)user_pgd; 1403 1404 if (user_pgd != NULL) { 1405 user_pgd[pgd_index(VSYSCALL_START)] = 1406 __pgd(__pa(level3_user_vsyscall) | _PAGE_TABLE); 1407 ret = 0; 1408 } 1409 1410 BUG_ON(PagePinned(virt_to_page(xen_get_user_pgd(pgd)))); 1411 } 1412 #endif 1413 1414 return ret; 1415 } 1416 1417 static void xen_pgd_free(struct mm_struct *mm, pgd_t *pgd) 1418 { 1419 #ifdef CONFIG_X86_64 1420 pgd_t *user_pgd = xen_get_user_pgd(pgd); 1421 1422 if (user_pgd) 1423 free_page((unsigned long)user_pgd); 1424 #endif 1425 } 1426 1427 static __init pte_t mask_rw_pte(pte_t *ptep, pte_t pte) 1428 { 1429 unsigned long pfn = pte_pfn(pte); 1430 1431 #ifdef CONFIG_X86_32 1432 /* If there's an existing pte, then don't allow _PAGE_RW to be set */ 1433 if (pte_val_ma(*ptep) & _PAGE_PRESENT) 1434 pte = __pte_ma(((pte_val_ma(*ptep) & _PAGE_RW) | ~_PAGE_RW) & 1435 pte_val_ma(pte)); 1436 #endif 1437 1438 /* 1439 * If the new pfn is within the range of the newly allocated 1440 * kernel pagetable, and it isn't being mapped into an 1441 * early_ioremap fixmap slot, make sure it is RO. 1442 */ 1443 if (!is_early_ioremap_ptep(ptep) && 1444 pfn >= e820_table_start && pfn < e820_table_end) 1445 pte = pte_wrprotect(pte); 1446 1447 return pte; 1448 } 1449 1450 /* Init-time set_pte while constructing initial pagetables, which 1451 doesn't allow RO pagetable pages to be remapped RW */ 1452 static __init void xen_set_pte_init(pte_t *ptep, pte_t pte) 1453 { 1454 pte = mask_rw_pte(ptep, pte); 1455 1456 xen_set_pte(ptep, pte); 1457 } 1458 1459 static void pin_pagetable_pfn(unsigned cmd, unsigned long pfn) 1460 { 1461 struct mmuext_op op; 1462 op.cmd = cmd; 1463 op.arg1.mfn = pfn_to_mfn(pfn); 1464 if (HYPERVISOR_mmuext_op(&op, 1, NULL, DOMID_SELF)) 1465 BUG(); 1466 } 1467 1468 /* Early in boot, while setting up the initial pagetable, assume 1469 everything is pinned. */ 1470 static __init void xen_alloc_pte_init(struct mm_struct *mm, unsigned long pfn) 1471 { 1472 #ifdef CONFIG_FLATMEM 1473 BUG_ON(mem_map); /* should only be used early */ 1474 #endif 1475 make_lowmem_page_readonly(__va(PFN_PHYS(pfn))); 1476 pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn); 1477 } 1478 1479 /* Used for pmd and pud */ 1480 static __init void xen_alloc_pmd_init(struct mm_struct *mm, unsigned long pfn) 1481 { 1482 #ifdef CONFIG_FLATMEM 1483 BUG_ON(mem_map); /* should only be used early */ 1484 #endif 1485 make_lowmem_page_readonly(__va(PFN_PHYS(pfn))); 1486 } 1487 1488 /* Early release_pte assumes that all pts are pinned, since there's 1489 only init_mm and anything attached to that is pinned. */ 1490 static __init void xen_release_pte_init(unsigned long pfn) 1491 { 1492 pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, pfn); 1493 make_lowmem_page_readwrite(__va(PFN_PHYS(pfn))); 1494 } 1495 1496 static __init void xen_release_pmd_init(unsigned long pfn) 1497 { 1498 make_lowmem_page_readwrite(__va(PFN_PHYS(pfn))); 1499 } 1500 1501 /* This needs to make sure the new pte page is pinned iff its being 1502 attached to a pinned pagetable. */ 1503 static void xen_alloc_ptpage(struct mm_struct *mm, unsigned long pfn, unsigned level) 1504 { 1505 struct page *page = pfn_to_page(pfn); 1506 1507 if (PagePinned(virt_to_page(mm->pgd))) { 1508 SetPagePinned(page); 1509 1510 if (!PageHighMem(page)) { 1511 make_lowmem_page_readonly(__va(PFN_PHYS((unsigned long)pfn))); 1512 if (level == PT_PTE && USE_SPLIT_PTLOCKS) 1513 pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn); 1514 } else { 1515 /* make sure there are no stray mappings of 1516 this page */ 1517 kmap_flush_unused(); 1518 } 1519 } 1520 } 1521 1522 static void xen_alloc_pte(struct mm_struct *mm, unsigned long pfn) 1523 { 1524 xen_alloc_ptpage(mm, pfn, PT_PTE); 1525 } 1526 1527 static void xen_alloc_pmd(struct mm_struct *mm, unsigned long pfn) 1528 { 1529 xen_alloc_ptpage(mm, pfn, PT_PMD); 1530 } 1531 1532 /* This should never happen until we're OK to use struct page */ 1533 static void xen_release_ptpage(unsigned long pfn, unsigned level) 1534 { 1535 struct page *page = pfn_to_page(pfn); 1536 1537 if (PagePinned(page)) { 1538 if (!PageHighMem(page)) { 1539 if (level == PT_PTE && USE_SPLIT_PTLOCKS) 1540 pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, pfn); 1541 make_lowmem_page_readwrite(__va(PFN_PHYS(pfn))); 1542 } 1543 ClearPagePinned(page); 1544 } 1545 } 1546 1547 static void xen_release_pte(unsigned long pfn) 1548 { 1549 xen_release_ptpage(pfn, PT_PTE); 1550 } 1551 1552 static void xen_release_pmd(unsigned long pfn) 1553 { 1554 xen_release_ptpage(pfn, PT_PMD); 1555 } 1556 1557 #if PAGETABLE_LEVELS == 4 1558 static void xen_alloc_pud(struct mm_struct *mm, unsigned long pfn) 1559 { 1560 xen_alloc_ptpage(mm, pfn, PT_PUD); 1561 } 1562 1563 static void xen_release_pud(unsigned long pfn) 1564 { 1565 xen_release_ptpage(pfn, PT_PUD); 1566 } 1567 #endif 1568 1569 void __init xen_reserve_top(void) 1570 { 1571 #ifdef CONFIG_X86_32 1572 unsigned long top = HYPERVISOR_VIRT_START; 1573 struct xen_platform_parameters pp; 1574 1575 if (HYPERVISOR_xen_version(XENVER_platform_parameters, &pp) == 0) 1576 top = pp.virt_start; 1577 1578 reserve_top_address(-top); 1579 #endif /* CONFIG_X86_32 */ 1580 } 1581 1582 /* 1583 * Like __va(), but returns address in the kernel mapping (which is 1584 * all we have until the physical memory mapping has been set up. 1585 */ 1586 static void *__ka(phys_addr_t paddr) 1587 { 1588 #ifdef CONFIG_X86_64 1589 return (void *)(paddr + __START_KERNEL_map); 1590 #else 1591 return __va(paddr); 1592 #endif 1593 } 1594 1595 /* Convert a machine address to physical address */ 1596 static unsigned long m2p(phys_addr_t maddr) 1597 { 1598 phys_addr_t paddr; 1599 1600 maddr &= PTE_PFN_MASK; 1601 paddr = mfn_to_pfn(maddr >> PAGE_SHIFT) << PAGE_SHIFT; 1602 1603 return paddr; 1604 } 1605 1606 /* Convert a machine address to kernel virtual */ 1607 static void *m2v(phys_addr_t maddr) 1608 { 1609 return __ka(m2p(maddr)); 1610 } 1611 1612 /* Set the page permissions on an identity-mapped pages */ 1613 static void set_page_prot(void *addr, pgprot_t prot) 1614 { 1615 unsigned long pfn = __pa(addr) >> PAGE_SHIFT; 1616 pte_t pte = pfn_pte(pfn, prot); 1617 1618 if (HYPERVISOR_update_va_mapping((unsigned long)addr, pte, 0)) 1619 BUG(); 1620 } 1621 1622 static __init void xen_map_identity_early(pmd_t *pmd, unsigned long max_pfn) 1623 { 1624 unsigned pmdidx, pteidx; 1625 unsigned ident_pte; 1626 unsigned long pfn; 1627 1628 level1_ident_pgt = extend_brk(sizeof(pte_t) * LEVEL1_IDENT_ENTRIES, 1629 PAGE_SIZE); 1630 1631 ident_pte = 0; 1632 pfn = 0; 1633 for (pmdidx = 0; pmdidx < PTRS_PER_PMD && pfn < max_pfn; pmdidx++) { 1634 pte_t *pte_page; 1635 1636 /* Reuse or allocate a page of ptes */ 1637 if (pmd_present(pmd[pmdidx])) 1638 pte_page = m2v(pmd[pmdidx].pmd); 1639 else { 1640 /* Check for free pte pages */ 1641 if (ident_pte == LEVEL1_IDENT_ENTRIES) 1642 break; 1643 1644 pte_page = &level1_ident_pgt[ident_pte]; 1645 ident_pte += PTRS_PER_PTE; 1646 1647 pmd[pmdidx] = __pmd(__pa(pte_page) | _PAGE_TABLE); 1648 } 1649 1650 /* Install mappings */ 1651 for (pteidx = 0; pteidx < PTRS_PER_PTE; pteidx++, pfn++) { 1652 pte_t pte; 1653 1654 if (pfn > max_pfn_mapped) 1655 max_pfn_mapped = pfn; 1656 1657 if (!pte_none(pte_page[pteidx])) 1658 continue; 1659 1660 pte = pfn_pte(pfn, PAGE_KERNEL_EXEC); 1661 pte_page[pteidx] = pte; 1662 } 1663 } 1664 1665 for (pteidx = 0; pteidx < ident_pte; pteidx += PTRS_PER_PTE) 1666 set_page_prot(&level1_ident_pgt[pteidx], PAGE_KERNEL_RO); 1667 1668 set_page_prot(pmd, PAGE_KERNEL_RO); 1669 } 1670 1671 void __init xen_setup_machphys_mapping(void) 1672 { 1673 struct xen_machphys_mapping mapping; 1674 unsigned long machine_to_phys_nr_ents; 1675 1676 if (HYPERVISOR_memory_op(XENMEM_machphys_mapping, &mapping) == 0) { 1677 machine_to_phys_mapping = (unsigned long *)mapping.v_start; 1678 machine_to_phys_nr_ents = mapping.max_mfn + 1; 1679 } else { 1680 machine_to_phys_nr_ents = MACH2PHYS_NR_ENTRIES; 1681 } 1682 machine_to_phys_order = fls(machine_to_phys_nr_ents - 1); 1683 } 1684 1685 #ifdef CONFIG_X86_64 1686 static void convert_pfn_mfn(void *v) 1687 { 1688 pte_t *pte = v; 1689 int i; 1690 1691 /* All levels are converted the same way, so just treat them 1692 as ptes. */ 1693 for (i = 0; i < PTRS_PER_PTE; i++) 1694 pte[i] = xen_make_pte(pte[i].pte); 1695 } 1696 1697 /* 1698 * Set up the inital kernel pagetable. 1699 * 1700 * We can construct this by grafting the Xen provided pagetable into 1701 * head_64.S's preconstructed pagetables. We copy the Xen L2's into 1702 * level2_ident_pgt, level2_kernel_pgt and level2_fixmap_pgt. This 1703 * means that only the kernel has a physical mapping to start with - 1704 * but that's enough to get __va working. We need to fill in the rest 1705 * of the physical mapping once some sort of allocator has been set 1706 * up. 1707 */ 1708 __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd, 1709 unsigned long max_pfn) 1710 { 1711 pud_t *l3; 1712 pmd_t *l2; 1713 1714 /* Zap identity mapping */ 1715 init_level4_pgt[0] = __pgd(0); 1716 1717 /* Pre-constructed entries are in pfn, so convert to mfn */ 1718 convert_pfn_mfn(init_level4_pgt); 1719 convert_pfn_mfn(level3_ident_pgt); 1720 convert_pfn_mfn(level3_kernel_pgt); 1721 1722 l3 = m2v(pgd[pgd_index(__START_KERNEL_map)].pgd); 1723 l2 = m2v(l3[pud_index(__START_KERNEL_map)].pud); 1724 1725 memcpy(level2_ident_pgt, l2, sizeof(pmd_t) * PTRS_PER_PMD); 1726 memcpy(level2_kernel_pgt, l2, sizeof(pmd_t) * PTRS_PER_PMD); 1727 1728 l3 = m2v(pgd[pgd_index(__START_KERNEL_map + PMD_SIZE)].pgd); 1729 l2 = m2v(l3[pud_index(__START_KERNEL_map + PMD_SIZE)].pud); 1730 memcpy(level2_fixmap_pgt, l2, sizeof(pmd_t) * PTRS_PER_PMD); 1731 1732 /* Set up identity map */ 1733 xen_map_identity_early(level2_ident_pgt, max_pfn); 1734 1735 /* Make pagetable pieces RO */ 1736 set_page_prot(init_level4_pgt, PAGE_KERNEL_RO); 1737 set_page_prot(level3_ident_pgt, PAGE_KERNEL_RO); 1738 set_page_prot(level3_kernel_pgt, PAGE_KERNEL_RO); 1739 set_page_prot(level3_user_vsyscall, PAGE_KERNEL_RO); 1740 set_page_prot(level2_kernel_pgt, PAGE_KERNEL_RO); 1741 set_page_prot(level2_fixmap_pgt, PAGE_KERNEL_RO); 1742 1743 /* Pin down new L4 */ 1744 pin_pagetable_pfn(MMUEXT_PIN_L4_TABLE, 1745 PFN_DOWN(__pa_symbol(init_level4_pgt))); 1746 1747 /* Unpin Xen-provided one */ 1748 pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd))); 1749 1750 /* Switch over */ 1751 pgd = init_level4_pgt; 1752 1753 /* 1754 * At this stage there can be no user pgd, and no page 1755 * structure to attach it to, so make sure we just set kernel 1756 * pgd. 1757 */ 1758 xen_mc_batch(); 1759 __xen_write_cr3(true, __pa(pgd)); 1760 xen_mc_issue(PARAVIRT_LAZY_CPU); 1761 1762 memblock_x86_reserve_range(__pa(xen_start_info->pt_base), 1763 __pa(xen_start_info->pt_base + 1764 xen_start_info->nr_pt_frames * PAGE_SIZE), 1765 "XEN PAGETABLES"); 1766 1767 return pgd; 1768 } 1769 #else /* !CONFIG_X86_64 */ 1770 static RESERVE_BRK_ARRAY(pmd_t, initial_kernel_pmd, PTRS_PER_PMD); 1771 static RESERVE_BRK_ARRAY(pmd_t, swapper_kernel_pmd, PTRS_PER_PMD); 1772 1773 static __init void xen_write_cr3_init(unsigned long cr3) 1774 { 1775 unsigned long pfn = PFN_DOWN(__pa(swapper_pg_dir)); 1776 1777 BUG_ON(read_cr3() != __pa(initial_page_table)); 1778 BUG_ON(cr3 != __pa(swapper_pg_dir)); 1779 1780 /* 1781 * We are switching to swapper_pg_dir for the first time (from 1782 * initial_page_table) and therefore need to mark that page 1783 * read-only and then pin it. 1784 * 1785 * Xen disallows sharing of kernel PMDs for PAE 1786 * guests. Therefore we must copy the kernel PMD from 1787 * initial_page_table into a new kernel PMD to be used in 1788 * swapper_pg_dir. 1789 */ 1790 swapper_kernel_pmd = 1791 extend_brk(sizeof(pmd_t) * PTRS_PER_PMD, PAGE_SIZE); 1792 memcpy(swapper_kernel_pmd, initial_kernel_pmd, 1793 sizeof(pmd_t) * PTRS_PER_PMD); 1794 swapper_pg_dir[KERNEL_PGD_BOUNDARY] = 1795 __pgd(__pa(swapper_kernel_pmd) | _PAGE_PRESENT); 1796 set_page_prot(swapper_kernel_pmd, PAGE_KERNEL_RO); 1797 1798 set_page_prot(swapper_pg_dir, PAGE_KERNEL_RO); 1799 xen_write_cr3(cr3); 1800 pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE, pfn); 1801 1802 pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, 1803 PFN_DOWN(__pa(initial_page_table))); 1804 set_page_prot(initial_page_table, PAGE_KERNEL); 1805 set_page_prot(initial_kernel_pmd, PAGE_KERNEL); 1806 1807 pv_mmu_ops.write_cr3 = &xen_write_cr3; 1808 } 1809 1810 __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd, 1811 unsigned long max_pfn) 1812 { 1813 pmd_t *kernel_pmd; 1814 1815 initial_kernel_pmd = 1816 extend_brk(sizeof(pmd_t) * PTRS_PER_PMD, PAGE_SIZE); 1817 1818 max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->pt_base) + 1819 xen_start_info->nr_pt_frames * PAGE_SIZE + 1820 512*1024); 1821 1822 kernel_pmd = m2v(pgd[KERNEL_PGD_BOUNDARY].pgd); 1823 memcpy(initial_kernel_pmd, kernel_pmd, sizeof(pmd_t) * PTRS_PER_PMD); 1824 1825 xen_map_identity_early(initial_kernel_pmd, max_pfn); 1826 1827 memcpy(initial_page_table, pgd, sizeof(pgd_t) * PTRS_PER_PGD); 1828 initial_page_table[KERNEL_PGD_BOUNDARY] = 1829 __pgd(__pa(initial_kernel_pmd) | _PAGE_PRESENT); 1830 1831 set_page_prot(initial_kernel_pmd, PAGE_KERNEL_RO); 1832 set_page_prot(initial_page_table, PAGE_KERNEL_RO); 1833 set_page_prot(empty_zero_page, PAGE_KERNEL_RO); 1834 1835 pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd))); 1836 1837 pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE, 1838 PFN_DOWN(__pa(initial_page_table))); 1839 xen_write_cr3(__pa(initial_page_table)); 1840 1841 memblock_x86_reserve_range(__pa(xen_start_info->pt_base), 1842 __pa(xen_start_info->pt_base + 1843 xen_start_info->nr_pt_frames * PAGE_SIZE), 1844 "XEN PAGETABLES"); 1845 1846 return initial_page_table; 1847 } 1848 #endif /* CONFIG_X86_64 */ 1849 1850 static unsigned char dummy_mapping[PAGE_SIZE] __page_aligned_bss; 1851 1852 static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot) 1853 { 1854 pte_t pte; 1855 1856 phys >>= PAGE_SHIFT; 1857 1858 switch (idx) { 1859 case FIX_BTMAP_END ... FIX_BTMAP_BEGIN: 1860 #ifdef CONFIG_X86_F00F_BUG 1861 case FIX_F00F_IDT: 1862 #endif 1863 #ifdef CONFIG_X86_32 1864 case FIX_WP_TEST: 1865 case FIX_VDSO: 1866 # ifdef CONFIG_HIGHMEM 1867 case FIX_KMAP_BEGIN ... FIX_KMAP_END: 1868 # endif 1869 #else 1870 case VSYSCALL_LAST_PAGE ... VSYSCALL_FIRST_PAGE: 1871 #endif 1872 case FIX_TEXT_POKE0: 1873 case FIX_TEXT_POKE1: 1874 /* All local page mappings */ 1875 pte = pfn_pte(phys, prot); 1876 break; 1877 1878 #ifdef CONFIG_X86_LOCAL_APIC 1879 case FIX_APIC_BASE: /* maps dummy local APIC */ 1880 pte = pfn_pte(PFN_DOWN(__pa(dummy_mapping)), PAGE_KERNEL); 1881 break; 1882 #endif 1883 1884 #ifdef CONFIG_X86_IO_APIC 1885 case FIX_IO_APIC_BASE_0 ... FIX_IO_APIC_BASE_END: 1886 /* 1887 * We just don't map the IO APIC - all access is via 1888 * hypercalls. Keep the address in the pte for reference. 1889 */ 1890 pte = pfn_pte(PFN_DOWN(__pa(dummy_mapping)), PAGE_KERNEL); 1891 break; 1892 #endif 1893 1894 case FIX_PARAVIRT_BOOTMAP: 1895 /* This is an MFN, but it isn't an IO mapping from the 1896 IO domain */ 1897 pte = mfn_pte(phys, prot); 1898 break; 1899 1900 default: 1901 /* By default, set_fixmap is used for hardware mappings */ 1902 pte = mfn_pte(phys, __pgprot(pgprot_val(prot) | _PAGE_IOMAP)); 1903 break; 1904 } 1905 1906 __native_set_fixmap(idx, pte); 1907 1908 #ifdef CONFIG_X86_64 1909 /* Replicate changes to map the vsyscall page into the user 1910 pagetable vsyscall mapping. */ 1911 if (idx >= VSYSCALL_LAST_PAGE && idx <= VSYSCALL_FIRST_PAGE) { 1912 unsigned long vaddr = __fix_to_virt(idx); 1913 set_pte_vaddr_pud(level3_user_vsyscall, vaddr, pte); 1914 } 1915 #endif 1916 } 1917 1918 __init void xen_ident_map_ISA(void) 1919 { 1920 unsigned long pa; 1921 1922 /* 1923 * If we're dom0, then linear map the ISA machine addresses into 1924 * the kernel's address space. 1925 */ 1926 if (!xen_initial_domain()) 1927 return; 1928 1929 xen_raw_printk("Xen: setup ISA identity maps\n"); 1930 1931 for (pa = ISA_START_ADDRESS; pa < ISA_END_ADDRESS; pa += PAGE_SIZE) { 1932 pte_t pte = mfn_pte(PFN_DOWN(pa), PAGE_KERNEL_IO); 1933 1934 if (HYPERVISOR_update_va_mapping(PAGE_OFFSET + pa, pte, 0)) 1935 BUG(); 1936 } 1937 1938 xen_flush_tlb(); 1939 } 1940 1941 static __init void xen_post_allocator_init(void) 1942 { 1943 pv_mmu_ops.set_pte = xen_set_pte; 1944 pv_mmu_ops.set_pmd = xen_set_pmd; 1945 pv_mmu_ops.set_pud = xen_set_pud; 1946 #if PAGETABLE_LEVELS == 4 1947 pv_mmu_ops.set_pgd = xen_set_pgd; 1948 #endif 1949 1950 /* This will work as long as patching hasn't happened yet 1951 (which it hasn't) */ 1952 pv_mmu_ops.alloc_pte = xen_alloc_pte; 1953 pv_mmu_ops.alloc_pmd = xen_alloc_pmd; 1954 pv_mmu_ops.release_pte = xen_release_pte; 1955 pv_mmu_ops.release_pmd = xen_release_pmd; 1956 #if PAGETABLE_LEVELS == 4 1957 pv_mmu_ops.alloc_pud = xen_alloc_pud; 1958 pv_mmu_ops.release_pud = xen_release_pud; 1959 #endif 1960 1961 #ifdef CONFIG_X86_64 1962 SetPagePinned(virt_to_page(level3_user_vsyscall)); 1963 #endif 1964 xen_mark_init_mm_pinned(); 1965 } 1966 1967 static void xen_leave_lazy_mmu(void) 1968 { 1969 preempt_disable(); 1970 xen_mc_flush(); 1971 paravirt_leave_lazy_mmu(); 1972 preempt_enable(); 1973 } 1974 1975 static const struct pv_mmu_ops xen_mmu_ops __initdata = { 1976 .read_cr2 = xen_read_cr2, 1977 .write_cr2 = xen_write_cr2, 1978 1979 .read_cr3 = xen_read_cr3, 1980 #ifdef CONFIG_X86_32 1981 .write_cr3 = xen_write_cr3_init, 1982 #else 1983 .write_cr3 = xen_write_cr3, 1984 #endif 1985 1986 .flush_tlb_user = xen_flush_tlb, 1987 .flush_tlb_kernel = xen_flush_tlb, 1988 .flush_tlb_single = xen_flush_tlb_single, 1989 .flush_tlb_others = xen_flush_tlb_others, 1990 1991 .pte_update = paravirt_nop, 1992 .pte_update_defer = paravirt_nop, 1993 1994 .pgd_alloc = xen_pgd_alloc, 1995 .pgd_free = xen_pgd_free, 1996 1997 .alloc_pte = xen_alloc_pte_init, 1998 .release_pte = xen_release_pte_init, 1999 .alloc_pmd = xen_alloc_pmd_init, 2000 .release_pmd = xen_release_pmd_init, 2001 2002 .set_pte = xen_set_pte_init, 2003 .set_pte_at = xen_set_pte_at, 2004 .set_pmd = xen_set_pmd_hyper, 2005 2006 .ptep_modify_prot_start = __ptep_modify_prot_start, 2007 .ptep_modify_prot_commit = __ptep_modify_prot_commit, 2008 2009 .pte_val = PV_CALLEE_SAVE(xen_pte_val), 2010 .pgd_val = PV_CALLEE_SAVE(xen_pgd_val), 2011 2012 .make_pte = PV_CALLEE_SAVE(xen_make_pte), 2013 .make_pgd = PV_CALLEE_SAVE(xen_make_pgd), 2014 2015 #ifdef CONFIG_X86_PAE 2016 .set_pte_atomic = xen_set_pte_atomic, 2017 .pte_clear = xen_pte_clear, 2018 .pmd_clear = xen_pmd_clear, 2019 #endif /* CONFIG_X86_PAE */ 2020 .set_pud = xen_set_pud_hyper, 2021 2022 .make_pmd = PV_CALLEE_SAVE(xen_make_pmd), 2023 .pmd_val = PV_CALLEE_SAVE(xen_pmd_val), 2024 2025 #if PAGETABLE_LEVELS == 4 2026 .pud_val = PV_CALLEE_SAVE(xen_pud_val), 2027 .make_pud = PV_CALLEE_SAVE(xen_make_pud), 2028 .set_pgd = xen_set_pgd_hyper, 2029 2030 .alloc_pud = xen_alloc_pmd_init, 2031 .release_pud = xen_release_pmd_init, 2032 #endif /* PAGETABLE_LEVELS == 4 */ 2033 2034 .activate_mm = xen_activate_mm, 2035 .dup_mmap = xen_dup_mmap, 2036 .exit_mmap = xen_exit_mmap, 2037 2038 .lazy_mode = { 2039 .enter = paravirt_enter_lazy_mmu, 2040 .leave = xen_leave_lazy_mmu, 2041 }, 2042 2043 .set_fixmap = xen_set_fixmap, 2044 }; 2045 2046 void __init xen_init_mmu_ops(void) 2047 { 2048 x86_init.paging.pagetable_setup_start = xen_pagetable_setup_start; 2049 x86_init.paging.pagetable_setup_done = xen_pagetable_setup_done; 2050 pv_mmu_ops = xen_mmu_ops; 2051 2052 memset(dummy_mapping, 0xff, PAGE_SIZE); 2053 } 2054 2055 /* Protected by xen_reservation_lock. */ 2056 #define MAX_CONTIG_ORDER 9 /* 2MB */ 2057 static unsigned long discontig_frames[1<<MAX_CONTIG_ORDER]; 2058 2059 #define VOID_PTE (mfn_pte(0, __pgprot(0))) 2060 static void xen_zap_pfn_range(unsigned long vaddr, unsigned int order, 2061 unsigned long *in_frames, 2062 unsigned long *out_frames) 2063 { 2064 int i; 2065 struct multicall_space mcs; 2066 2067 xen_mc_batch(); 2068 for (i = 0; i < (1UL<<order); i++, vaddr += PAGE_SIZE) { 2069 mcs = __xen_mc_entry(0); 2070 2071 if (in_frames) 2072 in_frames[i] = virt_to_mfn(vaddr); 2073 2074 MULTI_update_va_mapping(mcs.mc, vaddr, VOID_PTE, 0); 2075 set_phys_to_machine(virt_to_pfn(vaddr), INVALID_P2M_ENTRY); 2076 2077 if (out_frames) 2078 out_frames[i] = virt_to_pfn(vaddr); 2079 } 2080 xen_mc_issue(0); 2081 } 2082 2083 /* 2084 * Update the pfn-to-mfn mappings for a virtual address range, either to 2085 * point to an array of mfns, or contiguously from a single starting 2086 * mfn. 2087 */ 2088 static void xen_remap_exchanged_ptes(unsigned long vaddr, int order, 2089 unsigned long *mfns, 2090 unsigned long first_mfn) 2091 { 2092 unsigned i, limit; 2093 unsigned long mfn; 2094 2095 xen_mc_batch(); 2096 2097 limit = 1u << order; 2098 for (i = 0; i < limit; i++, vaddr += PAGE_SIZE) { 2099 struct multicall_space mcs; 2100 unsigned flags; 2101 2102 mcs = __xen_mc_entry(0); 2103 if (mfns) 2104 mfn = mfns[i]; 2105 else 2106 mfn = first_mfn + i; 2107 2108 if (i < (limit - 1)) 2109 flags = 0; 2110 else { 2111 if (order == 0) 2112 flags = UVMF_INVLPG | UVMF_ALL; 2113 else 2114 flags = UVMF_TLB_FLUSH | UVMF_ALL; 2115 } 2116 2117 MULTI_update_va_mapping(mcs.mc, vaddr, 2118 mfn_pte(mfn, PAGE_KERNEL), flags); 2119 2120 set_phys_to_machine(virt_to_pfn(vaddr), mfn); 2121 } 2122 2123 xen_mc_issue(0); 2124 } 2125 2126 /* 2127 * Perform the hypercall to exchange a region of our pfns to point to 2128 * memory with the required contiguous alignment. Takes the pfns as 2129 * input, and populates mfns as output. 2130 * 2131 * Returns a success code indicating whether the hypervisor was able to 2132 * satisfy the request or not. 2133 */ 2134 static int xen_exchange_memory(unsigned long extents_in, unsigned int order_in, 2135 unsigned long *pfns_in, 2136 unsigned long extents_out, 2137 unsigned int order_out, 2138 unsigned long *mfns_out, 2139 unsigned int address_bits) 2140 { 2141 long rc; 2142 int success; 2143 2144 struct xen_memory_exchange exchange = { 2145 .in = { 2146 .nr_extents = extents_in, 2147 .extent_order = order_in, 2148 .extent_start = pfns_in, 2149 .domid = DOMID_SELF 2150 }, 2151 .out = { 2152 .nr_extents = extents_out, 2153 .extent_order = order_out, 2154 .extent_start = mfns_out, 2155 .address_bits = address_bits, 2156 .domid = DOMID_SELF 2157 } 2158 }; 2159 2160 BUG_ON(extents_in << order_in != extents_out << order_out); 2161 2162 rc = HYPERVISOR_memory_op(XENMEM_exchange, &exchange); 2163 success = (exchange.nr_exchanged == extents_in); 2164 2165 BUG_ON(!success && ((exchange.nr_exchanged != 0) || (rc == 0))); 2166 BUG_ON(success && (rc != 0)); 2167 2168 return success; 2169 } 2170 2171 int xen_create_contiguous_region(unsigned long vstart, unsigned int order, 2172 unsigned int address_bits) 2173 { 2174 unsigned long *in_frames = discontig_frames, out_frame; 2175 unsigned long flags; 2176 int success; 2177 2178 /* 2179 * Currently an auto-translated guest will not perform I/O, nor will 2180 * it require PAE page directories below 4GB. Therefore any calls to 2181 * this function are redundant and can be ignored. 2182 */ 2183 2184 if (xen_feature(XENFEAT_auto_translated_physmap)) 2185 return 0; 2186 2187 if (unlikely(order > MAX_CONTIG_ORDER)) 2188 return -ENOMEM; 2189 2190 memset((void *) vstart, 0, PAGE_SIZE << order); 2191 2192 spin_lock_irqsave(&xen_reservation_lock, flags); 2193 2194 /* 1. Zap current PTEs, remembering MFNs. */ 2195 xen_zap_pfn_range(vstart, order, in_frames, NULL); 2196 2197 /* 2. Get a new contiguous memory extent. */ 2198 out_frame = virt_to_pfn(vstart); 2199 success = xen_exchange_memory(1UL << order, 0, in_frames, 2200 1, order, &out_frame, 2201 address_bits); 2202 2203 /* 3. Map the new extent in place of old pages. */ 2204 if (success) 2205 xen_remap_exchanged_ptes(vstart, order, NULL, out_frame); 2206 else 2207 xen_remap_exchanged_ptes(vstart, order, in_frames, 0); 2208 2209 spin_unlock_irqrestore(&xen_reservation_lock, flags); 2210 2211 return success ? 0 : -ENOMEM; 2212 } 2213 EXPORT_SYMBOL_GPL(xen_create_contiguous_region); 2214 2215 void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order) 2216 { 2217 unsigned long *out_frames = discontig_frames, in_frame; 2218 unsigned long flags; 2219 int success; 2220 2221 if (xen_feature(XENFEAT_auto_translated_physmap)) 2222 return; 2223 2224 if (unlikely(order > MAX_CONTIG_ORDER)) 2225 return; 2226 2227 memset((void *) vstart, 0, PAGE_SIZE << order); 2228 2229 spin_lock_irqsave(&xen_reservation_lock, flags); 2230 2231 /* 1. Find start MFN of contiguous extent. */ 2232 in_frame = virt_to_mfn(vstart); 2233 2234 /* 2. Zap current PTEs. */ 2235 xen_zap_pfn_range(vstart, order, NULL, out_frames); 2236 2237 /* 3. Do the exchange for non-contiguous MFNs. */ 2238 success = xen_exchange_memory(1, order, &in_frame, 1UL << order, 2239 0, out_frames, 0); 2240 2241 /* 4. Map new pages in place of old pages. */ 2242 if (success) 2243 xen_remap_exchanged_ptes(vstart, order, out_frames, 0); 2244 else 2245 xen_remap_exchanged_ptes(vstart, order, NULL, in_frame); 2246 2247 spin_unlock_irqrestore(&xen_reservation_lock, flags); 2248 } 2249 EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region); 2250 2251 #ifdef CONFIG_XEN_PVHVM 2252 static void xen_hvm_exit_mmap(struct mm_struct *mm) 2253 { 2254 struct xen_hvm_pagetable_dying a; 2255 int rc; 2256 2257 a.domid = DOMID_SELF; 2258 a.gpa = __pa(mm->pgd); 2259 rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a); 2260 WARN_ON_ONCE(rc < 0); 2261 } 2262 2263 static int is_pagetable_dying_supported(void) 2264 { 2265 struct xen_hvm_pagetable_dying a; 2266 int rc = 0; 2267 2268 a.domid = DOMID_SELF; 2269 a.gpa = 0x00; 2270 rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a); 2271 if (rc < 0) { 2272 printk(KERN_DEBUG "HVMOP_pagetable_dying not supported\n"); 2273 return 0; 2274 } 2275 return 1; 2276 } 2277 2278 void __init xen_hvm_init_mmu_ops(void) 2279 { 2280 if (is_pagetable_dying_supported()) 2281 pv_mmu_ops.exit_mmap = xen_hvm_exit_mmap; 2282 } 2283 #endif 2284 2285 #define REMAP_BATCH_SIZE 16 2286 2287 struct remap_data { 2288 unsigned long mfn; 2289 pgprot_t prot; 2290 struct mmu_update *mmu_update; 2291 }; 2292 2293 static int remap_area_mfn_pte_fn(pte_t *ptep, pgtable_t token, 2294 unsigned long addr, void *data) 2295 { 2296 struct remap_data *rmd = data; 2297 pte_t pte = pte_mkspecial(pfn_pte(rmd->mfn++, rmd->prot)); 2298 2299 rmd->mmu_update->ptr = arbitrary_virt_to_machine(ptep).maddr; 2300 rmd->mmu_update->val = pte_val_ma(pte); 2301 rmd->mmu_update++; 2302 2303 return 0; 2304 } 2305 2306 int xen_remap_domain_mfn_range(struct vm_area_struct *vma, 2307 unsigned long addr, 2308 unsigned long mfn, int nr, 2309 pgprot_t prot, unsigned domid) 2310 { 2311 struct remap_data rmd; 2312 struct mmu_update mmu_update[REMAP_BATCH_SIZE]; 2313 int batch; 2314 unsigned long range; 2315 int err = 0; 2316 2317 prot = __pgprot(pgprot_val(prot) | _PAGE_IOMAP); 2318 2319 BUG_ON(!((vma->vm_flags & (VM_PFNMAP | VM_RESERVED | VM_IO)) == 2320 (VM_PFNMAP | VM_RESERVED | VM_IO))); 2321 2322 rmd.mfn = mfn; 2323 rmd.prot = prot; 2324 2325 while (nr) { 2326 batch = min(REMAP_BATCH_SIZE, nr); 2327 range = (unsigned long)batch << PAGE_SHIFT; 2328 2329 rmd.mmu_update = mmu_update; 2330 err = apply_to_page_range(vma->vm_mm, addr, range, 2331 remap_area_mfn_pte_fn, &rmd); 2332 if (err) 2333 goto out; 2334 2335 err = -EFAULT; 2336 if (HYPERVISOR_mmu_update(mmu_update, batch, NULL, domid) < 0) 2337 goto out; 2338 2339 nr -= batch; 2340 addr += range; 2341 } 2342 2343 err = 0; 2344 out: 2345 2346 flush_tlb_all(); 2347 2348 return err; 2349 } 2350 EXPORT_SYMBOL_GPL(xen_remap_domain_mfn_range); 2351 2352 #ifdef CONFIG_XEN_DEBUG_FS 2353 2354 static struct dentry *d_mmu_debug; 2355 2356 static int __init xen_mmu_debugfs(void) 2357 { 2358 struct dentry *d_xen = xen_init_debugfs(); 2359 2360 if (d_xen == NULL) 2361 return -ENOMEM; 2362 2363 d_mmu_debug = debugfs_create_dir("mmu", d_xen); 2364 2365 debugfs_create_u8("zero_stats", 0644, d_mmu_debug, &zero_stats); 2366 2367 debugfs_create_u32("pgd_update", 0444, d_mmu_debug, &mmu_stats.pgd_update); 2368 debugfs_create_u32("pgd_update_pinned", 0444, d_mmu_debug, 2369 &mmu_stats.pgd_update_pinned); 2370 debugfs_create_u32("pgd_update_batched", 0444, d_mmu_debug, 2371 &mmu_stats.pgd_update_pinned); 2372 2373 debugfs_create_u32("pud_update", 0444, d_mmu_debug, &mmu_stats.pud_update); 2374 debugfs_create_u32("pud_update_pinned", 0444, d_mmu_debug, 2375 &mmu_stats.pud_update_pinned); 2376 debugfs_create_u32("pud_update_batched", 0444, d_mmu_debug, 2377 &mmu_stats.pud_update_pinned); 2378 2379 debugfs_create_u32("pmd_update", 0444, d_mmu_debug, &mmu_stats.pmd_update); 2380 debugfs_create_u32("pmd_update_pinned", 0444, d_mmu_debug, 2381 &mmu_stats.pmd_update_pinned); 2382 debugfs_create_u32("pmd_update_batched", 0444, d_mmu_debug, 2383 &mmu_stats.pmd_update_pinned); 2384 2385 debugfs_create_u32("pte_update", 0444, d_mmu_debug, &mmu_stats.pte_update); 2386 // debugfs_create_u32("pte_update_pinned", 0444, d_mmu_debug, 2387 // &mmu_stats.pte_update_pinned); 2388 debugfs_create_u32("pte_update_batched", 0444, d_mmu_debug, 2389 &mmu_stats.pte_update_pinned); 2390 2391 debugfs_create_u32("mmu_update", 0444, d_mmu_debug, &mmu_stats.mmu_update); 2392 debugfs_create_u32("mmu_update_extended", 0444, d_mmu_debug, 2393 &mmu_stats.mmu_update_extended); 2394 xen_debugfs_create_u32_array("mmu_update_histo", 0444, d_mmu_debug, 2395 mmu_stats.mmu_update_histo, 20); 2396 2397 debugfs_create_u32("set_pte_at", 0444, d_mmu_debug, &mmu_stats.set_pte_at); 2398 debugfs_create_u32("set_pte_at_batched", 0444, d_mmu_debug, 2399 &mmu_stats.set_pte_at_batched); 2400 debugfs_create_u32("set_pte_at_current", 0444, d_mmu_debug, 2401 &mmu_stats.set_pte_at_current); 2402 debugfs_create_u32("set_pte_at_kernel", 0444, d_mmu_debug, 2403 &mmu_stats.set_pte_at_kernel); 2404 2405 debugfs_create_u32("prot_commit", 0444, d_mmu_debug, &mmu_stats.prot_commit); 2406 debugfs_create_u32("prot_commit_batched", 0444, d_mmu_debug, 2407 &mmu_stats.prot_commit_batched); 2408 2409 return 0; 2410 } 2411 fs_initcall(xen_mmu_debugfs); 2412 2413 #endif /* CONFIG_XEN_DEBUG_FS */ 2414