2 * Xen leaves the responsibility for maintaining p2m mappings to the
3 * guests themselves, but it must also access and update the p2m array
4 * during suspend/resume when all the pages are reallocated.
6 * The logical flat p2m table is mapped to a linear kernel memory area.
7 * For accesses by Xen a three-level tree linked via mfns only is set up to
8 * allow the address space to be sparse.
14 * p2m_mid_mfn p2m_mid_mfn
18 * The p2m_mid_mfn pages are mapped by p2m_top_mfn_p.
20 * The p2m_top_mfn level is limited to 1 page, so the maximum representable
21 * pseudo-physical address space is:
22 * P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE pages
24 * P2M_PER_PAGE depends on the architecture, as a mfn is always
25 * unsigned long (8 bytes on 64-bit, 4 bytes on 32), leading to
26 * 512 and 1024 entries respectively.
28 * In short, these structures contain the Machine Frame Number (MFN) of the PFN.
30 * However not all entries are filled with MFNs. Specifically for all other
31 * leaf entries, or for the top root, or middle one, for which there is a void
32 * entry, we assume it is "missing". So (for example)
33 * pfn_to_mfn(0x90909090)=INVALID_P2M_ENTRY.
34 * We have a dedicated page p2m_missing with all entries being
35 * INVALID_P2M_ENTRY. This page may be referenced multiple times in the p2m
36 * list/tree in case there are multiple areas with P2M_PER_PAGE invalid pfns.
38 * We also have the possibility of setting 1-1 mappings on certain regions, so
40 * pfn_to_mfn(0xc0000)=0xc0000
42 * The benefit of this is, that we can assume for non-RAM regions (think
43 * PCI BARs, or ACPI spaces), we can create mappings easily because we
44 * get the PFN value to match the MFN.
46 * For this to work efficiently we have one new page p2m_identity. All entries
47 * in p2m_identity are set to INVALID_P2M_ENTRY type (Xen toolstack only
48 * recognizes that and MFNs, no other fancy value).
50 * On lookup we spot that the entry points to p2m_identity and return the
51 * identity value instead of dereferencing and returning INVALID_P2M_ENTRY.
52 * If the entry points to an allocated page, we just proceed as before and
53 * return the PFN. If the PFN has IDENTITY_FRAME_BIT set we unmask that in
54 * appropriate functions (pfn_to_mfn).
56 * The reason for having the IDENTITY_FRAME_BIT instead of just returning the
57 * PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
58 * non-identity pfn. To protect ourselves against we elect to set (and get) the
59 * IDENTITY_FRAME_BIT on all identity mapped PFNs.
62 #include <linux/init.h>
63 #include <linux/module.h>
64 #include <linux/list.h>
65 #include <linux/hash.h>
66 #include <linux/sched.h>
67 #include <linux/seq_file.h>
68 #include <linux/bootmem.h>
69 #include <linux/slab.h>
71 #include <asm/cache.h>
72 #include <asm/setup.h>
73 #include <asm/uaccess.h>
75 #include <asm/xen/page.h>
76 #include <asm/xen/hypercall.h>
77 #include <asm/xen/hypervisor.h>
78 #include <xen/balloon.h>
79 #include <xen/grant_table.h>
82 #include "multicalls.h"
85 #define PMDS_PER_MID_PAGE (P2M_MID_PER_PAGE / PTRS_PER_PTE)
87 static void __init m2p_override_init(void);
89 unsigned long *xen_p2m_addr __read_mostly;
90 EXPORT_SYMBOL_GPL(xen_p2m_addr);
91 unsigned long xen_p2m_size __read_mostly;
92 EXPORT_SYMBOL_GPL(xen_p2m_size);
93 unsigned long xen_max_p2m_pfn __read_mostly;
94 EXPORT_SYMBOL_GPL(xen_max_p2m_pfn);
96 static DEFINE_SPINLOCK(p2m_update_lock);
98 static unsigned long *p2m_mid_missing_mfn;
99 static unsigned long *p2m_top_mfn;
100 static unsigned long **p2m_top_mfn_p;
101 static unsigned long *p2m_missing;
102 static unsigned long *p2m_identity;
103 static pte_t *p2m_missing_pte;
104 static pte_t *p2m_identity_pte;
106 static inline unsigned p2m_top_index(unsigned long pfn)
108 BUG_ON(pfn >= MAX_P2M_PFN);
109 return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
112 static inline unsigned p2m_mid_index(unsigned long pfn)
114 return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
117 static inline unsigned p2m_index(unsigned long pfn)
119 return pfn % P2M_PER_PAGE;
122 static void p2m_top_mfn_init(unsigned long *top)
126 for (i = 0; i < P2M_TOP_PER_PAGE; i++)
127 top[i] = virt_to_mfn(p2m_mid_missing_mfn);
130 static void p2m_top_mfn_p_init(unsigned long **top)
134 for (i = 0; i < P2M_TOP_PER_PAGE; i++)
135 top[i] = p2m_mid_missing_mfn;
138 static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf)
142 for (i = 0; i < P2M_MID_PER_PAGE; i++)
143 mid[i] = virt_to_mfn(leaf);
146 static void p2m_init(unsigned long *p2m)
150 for (i = 0; i < P2M_PER_PAGE; i++)
151 p2m[i] = INVALID_P2M_ENTRY;
154 static void p2m_init_identity(unsigned long *p2m, unsigned long pfn)
158 for (i = 0; i < P2M_PER_PAGE; i++)
159 p2m[i] = IDENTITY_FRAME(pfn + i);
162 static void * __ref alloc_p2m_page(void)
164 if (unlikely(!slab_is_available()))
165 return alloc_bootmem_align(PAGE_SIZE, PAGE_SIZE);
167 return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT);
170 static void __ref free_p2m_page(void *p)
172 if (unlikely(!slab_is_available())) {
173 free_bootmem((unsigned long)p, PAGE_SIZE);
177 free_page((unsigned long)p);
181 * Build the parallel p2m_top_mfn and p2m_mid_mfn structures
183 * This is called both at boot time, and after resuming from suspend:
184 * - At boot time we're called rather early, and must use alloc_bootmem*()
185 * to allocate memory.
187 * - After resume we're called from within stop_machine, but the mfn
188 * tree should already be completely allocated.
190 void __ref xen_build_mfn_list_list(void)
192 unsigned long pfn, mfn;
194 unsigned int level, topidx, mididx;
195 unsigned long *mid_mfn_p;
197 if (xen_feature(XENFEAT_auto_translated_physmap))
200 /* Pre-initialize p2m_top_mfn to be completely missing */
201 if (p2m_top_mfn == NULL) {
202 p2m_mid_missing_mfn = alloc_p2m_page();
203 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
205 p2m_top_mfn_p = alloc_p2m_page();
206 p2m_top_mfn_p_init(p2m_top_mfn_p);
208 p2m_top_mfn = alloc_p2m_page();
209 p2m_top_mfn_init(p2m_top_mfn);
211 /* Reinitialise, mfn's all change after migration */
212 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
215 for (pfn = 0; pfn < xen_max_p2m_pfn && pfn < MAX_P2M_PFN;
216 pfn += P2M_PER_PAGE) {
217 topidx = p2m_top_index(pfn);
218 mididx = p2m_mid_index(pfn);
220 mid_mfn_p = p2m_top_mfn_p[topidx];
221 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn),
223 BUG_ON(!ptep || level != PG_LEVEL_4K);
224 mfn = pte_mfn(*ptep);
225 ptep = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
227 /* Don't bother allocating any mfn mid levels if
228 * they're just missing, just update the stored mfn,
229 * since all could have changed over a migrate.
231 if (ptep == p2m_missing_pte || ptep == p2m_identity_pte) {
233 BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
234 p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
235 pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
239 if (mid_mfn_p == p2m_mid_missing_mfn) {
240 mid_mfn_p = alloc_p2m_page();
241 p2m_mid_mfn_init(mid_mfn_p, p2m_missing);
243 p2m_top_mfn_p[topidx] = mid_mfn_p;
246 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
247 mid_mfn_p[mididx] = mfn;
251 void xen_setup_mfn_list_list(void)
253 if (xen_feature(XENFEAT_auto_translated_physmap))
256 BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
258 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
259 virt_to_mfn(p2m_top_mfn);
260 HYPERVISOR_shared_info->arch.max_pfn = xen_max_p2m_pfn;
263 /* Set up p2m_top to point to the domain-builder provided p2m pages */
264 void __init xen_build_dynamic_phys_to_machine(void)
268 if (xen_feature(XENFEAT_auto_translated_physmap))
271 xen_p2m_addr = (unsigned long *)xen_start_info->mfn_list;
272 xen_p2m_size = ALIGN(xen_start_info->nr_pages, P2M_PER_PAGE);
274 for (pfn = xen_start_info->nr_pages; pfn < xen_p2m_size; pfn++)
275 xen_p2m_addr[pfn] = INVALID_P2M_ENTRY;
277 xen_max_p2m_pfn = xen_p2m_size;
280 #define P2M_TYPE_IDENTITY 0
281 #define P2M_TYPE_MISSING 1
282 #define P2M_TYPE_PFN 2
283 #define P2M_TYPE_UNKNOWN 3
285 static int xen_p2m_elem_type(unsigned long pfn)
289 if (pfn >= xen_p2m_size)
290 return P2M_TYPE_IDENTITY;
292 mfn = xen_p2m_addr[pfn];
294 if (mfn == INVALID_P2M_ENTRY)
295 return P2M_TYPE_MISSING;
297 if (mfn & IDENTITY_FRAME_BIT)
298 return P2M_TYPE_IDENTITY;
303 static void __init xen_rebuild_p2m_list(unsigned long *p2m)
305 unsigned int i, chunk;
312 p2m_missing = alloc_p2m_page();
313 p2m_init(p2m_missing);
314 p2m_identity = alloc_p2m_page();
315 p2m_init(p2m_identity);
317 p2m_missing_pte = alloc_p2m_page();
318 paravirt_alloc_pte(&init_mm, __pa(p2m_missing_pte) >> PAGE_SHIFT);
319 p2m_identity_pte = alloc_p2m_page();
320 paravirt_alloc_pte(&init_mm, __pa(p2m_identity_pte) >> PAGE_SHIFT);
321 for (i = 0; i < PTRS_PER_PTE; i++) {
322 set_pte(p2m_missing_pte + i,
323 pfn_pte(PFN_DOWN(__pa(p2m_missing)), PAGE_KERNEL_RO));
324 set_pte(p2m_identity_pte + i,
325 pfn_pte(PFN_DOWN(__pa(p2m_identity)), PAGE_KERNEL_RO));
328 for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += chunk) {
330 * Try to map missing/identity PMDs or p2m-pages if possible.
331 * We have to respect the structure of the mfn_list_list
332 * which will be built just afterwards.
333 * Chunk size to test is one p2m page if we are in the middle
334 * of a mfn_list_list mid page and the complete mid page area
335 * if we are at index 0 of the mid page. Please note that a
336 * mid page might cover more than one PMD, e.g. on 32 bit PAE
339 chunk = (pfn & (P2M_PER_PAGE * P2M_MID_PER_PAGE - 1)) ?
340 P2M_PER_PAGE : P2M_PER_PAGE * P2M_MID_PER_PAGE;
342 type = xen_p2m_elem_type(pfn);
344 if (type != P2M_TYPE_PFN)
345 for (i = 1; i < chunk; i++)
346 if (xen_p2m_elem_type(pfn + i) != type)
349 /* Reset to minimal chunk size. */
350 chunk = P2M_PER_PAGE;
352 if (type == P2M_TYPE_PFN || i < chunk) {
353 /* Use initial p2m page contents. */
355 mfns = alloc_p2m_page();
356 copy_page(mfns, xen_p2m_addr + pfn);
358 mfns = xen_p2m_addr + pfn;
360 ptep = populate_extra_pte((unsigned long)(p2m + pfn));
362 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL));
366 if (chunk == P2M_PER_PAGE) {
367 /* Map complete missing or identity p2m-page. */
368 mfns = (type == P2M_TYPE_MISSING) ?
369 p2m_missing : p2m_identity;
370 ptep = populate_extra_pte((unsigned long)(p2m + pfn));
372 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL_RO));
376 /* Complete missing or identity PMD(s) can be mapped. */
377 ptep = (type == P2M_TYPE_MISSING) ?
378 p2m_missing_pte : p2m_identity_pte;
379 for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
380 pmdp = populate_extra_pmd(
381 (unsigned long)(p2m + pfn) + i * PMD_SIZE);
382 set_pmd(pmdp, __pmd(__pa(ptep) | _KERNPG_TABLE));
387 void __init xen_vmalloc_p2m_tree(void)
389 static struct vm_struct vm;
392 vm.size = ALIGN(sizeof(unsigned long) * xen_max_p2m_pfn,
393 PMD_SIZE * PMDS_PER_MID_PAGE);
394 vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE);
395 pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size);
397 xen_max_p2m_pfn = vm.size / sizeof(unsigned long);
399 xen_rebuild_p2m_list(vm.addr);
401 xen_p2m_addr = vm.addr;
402 xen_p2m_size = xen_max_p2m_pfn;
409 unsigned long get_phys_to_machine(unsigned long pfn)
414 if (unlikely(pfn >= xen_p2m_size)) {
415 if (pfn < xen_max_p2m_pfn)
416 return xen_chk_extra_mem(pfn);
418 return IDENTITY_FRAME(pfn);
421 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
422 BUG_ON(!ptep || level != PG_LEVEL_4K);
425 * The INVALID_P2M_ENTRY is filled in both p2m_*identity
426 * and in p2m_*missing, so returning the INVALID_P2M_ENTRY
429 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
430 return IDENTITY_FRAME(pfn);
432 return xen_p2m_addr[pfn];
434 EXPORT_SYMBOL_GPL(get_phys_to_machine);
437 * Allocate new pmd(s). It is checked whether the old pmd is still in place.
438 * If not, nothing is changed. This is okay as the only reason for allocating
439 * a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual
440 * pmd. In case of PAE/x86-32 there are multiple pmds to allocate!
442 static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg)
445 pte_t *pte_newpg[PMDS_PER_MID_PAGE];
452 /* Do all allocations first to bail out in error case. */
453 for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
454 pte_newpg[i] = alloc_p2m_page();
456 for (i--; i >= 0; i--)
457 free_p2m_page(pte_newpg[i]);
463 vaddr = addr & ~(PMD_SIZE * PMDS_PER_MID_PAGE - 1);
465 for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
466 copy_page(pte_newpg[i], pte_pg);
467 paravirt_alloc_pte(&init_mm, __pa(pte_newpg[i]) >> PAGE_SHIFT);
469 pmdp = lookup_pmd_address(vaddr);
472 spin_lock_irqsave(&p2m_update_lock, flags);
474 ptechk = lookup_address(vaddr, &level);
475 if (ptechk == pte_pg) {
477 __pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE));
481 spin_unlock_irqrestore(&p2m_update_lock, flags);
484 paravirt_release_pte(__pa(pte_newpg[i]) >> PAGE_SHIFT);
485 free_p2m_page(pte_newpg[i]);
491 return lookup_address(addr, &level);
495 * Fully allocate the p2m structure for a given pfn. We need to check
496 * that both the top and mid levels are allocated, and make sure the
497 * parallel mfn tree is kept in sync. We may race with other cpus, so
498 * the new pages are installed with cmpxchg; if we lose the race then
499 * simply free the page we allocated and use the one that's there.
501 static bool alloc_p2m(unsigned long pfn)
503 unsigned topidx, mididx;
504 unsigned long *top_mfn_p, *mid_mfn;
505 pte_t *ptep, *pte_pg;
508 unsigned long addr = (unsigned long)(xen_p2m_addr + pfn);
509 unsigned long p2m_pfn;
511 topidx = p2m_top_index(pfn);
512 mididx = p2m_mid_index(pfn);
514 ptep = lookup_address(addr, &level);
515 BUG_ON(!ptep || level != PG_LEVEL_4K);
516 pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
518 if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) {
519 /* PMD level is missing, allocate a new one */
520 ptep = alloc_p2m_pmd(addr, pte_pg);
526 top_mfn_p = &p2m_top_mfn[topidx];
527 mid_mfn = ACCESS_ONCE(p2m_top_mfn_p[topidx]);
529 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
531 if (mid_mfn == p2m_mid_missing_mfn) {
532 /* Separately check the mid mfn level */
533 unsigned long missing_mfn;
534 unsigned long mid_mfn_mfn;
535 unsigned long old_mfn;
537 mid_mfn = alloc_p2m_page();
541 p2m_mid_mfn_init(mid_mfn, p2m_missing);
543 missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
544 mid_mfn_mfn = virt_to_mfn(mid_mfn);
545 old_mfn = cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn);
546 if (old_mfn != missing_mfn) {
547 free_p2m_page(mid_mfn);
548 mid_mfn = mfn_to_virt(old_mfn);
550 p2m_top_mfn_p[topidx] = mid_mfn;
557 p2m_pfn = pte_pfn(ACCESS_ONCE(*ptep));
558 if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) ||
559 p2m_pfn == PFN_DOWN(__pa(p2m_missing))) {
560 /* p2m leaf page is missing */
563 p2m = alloc_p2m_page();
567 if (p2m_pfn == PFN_DOWN(__pa(p2m_missing)))
570 p2m_init_identity(p2m, pfn);
572 spin_lock_irqsave(&p2m_update_lock, flags);
574 if (pte_pfn(*ptep) == p2m_pfn) {
576 pfn_pte(PFN_DOWN(__pa(p2m)), PAGE_KERNEL));
578 mid_mfn[mididx] = virt_to_mfn(p2m);
582 spin_unlock_irqrestore(&p2m_update_lock, flags);
591 unsigned long __init set_phys_range_identity(unsigned long pfn_s,
596 if (unlikely(pfn_s >= xen_p2m_size))
599 if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
600 return pfn_e - pfn_s;
605 if (pfn_e > xen_p2m_size)
606 pfn_e = xen_p2m_size;
608 for (pfn = pfn_s; pfn < pfn_e; pfn++)
609 xen_p2m_addr[pfn] = IDENTITY_FRAME(pfn);
614 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
619 /* don't track P2M changes in autotranslate guests */
620 if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
623 if (unlikely(pfn >= xen_p2m_size)) {
624 BUG_ON(mfn != INVALID_P2M_ENTRY);
628 if (likely(!xen_safe_write_ulong(xen_p2m_addr + pfn, mfn)))
631 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
632 BUG_ON(!ptep || level != PG_LEVEL_4K);
634 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_missing)))
635 return mfn == INVALID_P2M_ENTRY;
637 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
638 return mfn == IDENTITY_FRAME(pfn);
643 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
645 if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
649 return __set_phys_to_machine(pfn, mfn);
655 #define M2P_OVERRIDE_HASH_SHIFT 10
656 #define M2P_OVERRIDE_HASH (1 << M2P_OVERRIDE_HASH_SHIFT)
658 static struct list_head *m2p_overrides;
659 static DEFINE_SPINLOCK(m2p_override_lock);
661 static void __init m2p_override_init(void)
665 m2p_overrides = alloc_bootmem_align(
666 sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH,
667 sizeof(unsigned long));
669 for (i = 0; i < M2P_OVERRIDE_HASH; i++)
670 INIT_LIST_HEAD(&m2p_overrides[i]);
673 static unsigned long mfn_hash(unsigned long mfn)
675 return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT);
678 /* Add an MFN override for a particular page */
679 static int m2p_add_override(unsigned long mfn, struct page *page,
680 struct gnttab_map_grant_ref *kmap_op)
684 unsigned long uninitialized_var(address);
688 pfn = page_to_pfn(page);
689 if (!PageHighMem(page)) {
690 address = (unsigned long)__va(pfn << PAGE_SHIFT);
691 ptep = lookup_address(address, &level);
692 if (WARN(ptep == NULL || level != PG_LEVEL_4K,
693 "m2p_add_override: pfn %lx not mapped", pfn))
697 if (kmap_op != NULL) {
698 if (!PageHighMem(page)) {
699 struct multicall_space mcs =
700 xen_mc_entry(sizeof(*kmap_op));
702 MULTI_grant_table_op(mcs.mc,
703 GNTTABOP_map_grant_ref, kmap_op, 1);
705 xen_mc_issue(PARAVIRT_LAZY_MMU);
708 spin_lock_irqsave(&m2p_override_lock, flags);
709 list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]);
710 spin_unlock_irqrestore(&m2p_override_lock, flags);
712 /* p2m(m2p(mfn)) == mfn: the mfn is already present somewhere in
713 * this domain. Set the FOREIGN_FRAME_BIT in the p2m for the other
714 * pfn so that the following mfn_to_pfn(mfn) calls will return the
715 * pfn from the m2p_override (the backend pfn) instead.
716 * We need to do this because the pages shared by the frontend
717 * (xen-blkfront) can be already locked (lock_page, called by
718 * do_read_cache_page); when the userspace backend tries to use them
719 * with direct_IO, mfn_to_pfn returns the pfn of the frontend, so
720 * do_blockdev_direct_IO is going to try to lock the same pages
721 * again resulting in a deadlock.
722 * As a side effect get_user_pages_fast might not be safe on the
723 * frontend pages while they are being shared with the backend,
724 * because mfn_to_pfn (that ends up being called by GUPF) will
725 * return the backend pfn rather than the frontend pfn. */
726 pfn = mfn_to_pfn_no_overrides(mfn);
727 if (__pfn_to_mfn(pfn) == mfn)
728 set_phys_to_machine(pfn, FOREIGN_FRAME(mfn));
733 int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
734 struct gnttab_map_grant_ref *kmap_ops,
735 struct page **pages, unsigned int count)
741 if (xen_feature(XENFEAT_auto_translated_physmap))
746 paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
747 arch_enter_lazy_mmu_mode();
751 for (i = 0; i < count; i++) {
752 unsigned long mfn, pfn;
754 /* Do not add to override if the map failed. */
755 if (map_ops[i].status)
758 if (map_ops[i].flags & GNTMAP_contains_pte) {
759 pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
760 (map_ops[i].host_addr & ~PAGE_MASK));
763 mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
765 pfn = page_to_pfn(pages[i]);
767 WARN_ON(PagePrivate(pages[i]));
768 SetPagePrivate(pages[i]);
769 set_page_private(pages[i], mfn);
770 pages[i]->index = pfn_to_mfn(pfn);
772 if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
778 ret = m2p_add_override(mfn, pages[i], &kmap_ops[i]);
786 arch_leave_lazy_mmu_mode();
790 EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping);
792 static struct page *m2p_find_override(unsigned long mfn)
795 struct list_head *bucket;
796 struct page *p, *ret;
798 if (unlikely(!m2p_overrides))
802 bucket = &m2p_overrides[mfn_hash(mfn)];
804 spin_lock_irqsave(&m2p_override_lock, flags);
806 list_for_each_entry(p, bucket, lru) {
807 if (page_private(p) == mfn) {
813 spin_unlock_irqrestore(&m2p_override_lock, flags);
818 static int m2p_remove_override(struct page *page,
819 struct gnttab_map_grant_ref *kmap_op,
824 unsigned long uninitialized_var(address);
828 pfn = page_to_pfn(page);
830 if (!PageHighMem(page)) {
831 address = (unsigned long)__va(pfn << PAGE_SHIFT);
832 ptep = lookup_address(address, &level);
834 if (WARN(ptep == NULL || level != PG_LEVEL_4K,
835 "m2p_remove_override: pfn %lx not mapped", pfn))
839 spin_lock_irqsave(&m2p_override_lock, flags);
840 list_del(&page->lru);
841 spin_unlock_irqrestore(&m2p_override_lock, flags);
843 if (kmap_op != NULL) {
844 if (!PageHighMem(page)) {
845 struct multicall_space mcs;
846 struct gnttab_unmap_and_replace *unmap_op;
847 struct page *scratch_page = get_balloon_scratch_page();
848 unsigned long scratch_page_address = (unsigned long)
849 __va(page_to_pfn(scratch_page) << PAGE_SHIFT);
852 * It might be that we queued all the m2p grant table
853 * hypercalls in a multicall, then m2p_remove_override
854 * get called before the multicall has actually been
855 * issued. In this case handle is going to -1 because
856 * it hasn't been modified yet.
858 if (kmap_op->handle == -1)
861 * Now if kmap_op->handle is negative it means that the
862 * hypercall actually returned an error.
864 if (kmap_op->handle == GNTST_general_error) {
865 pr_warn("m2p_remove_override: pfn %lx mfn %lx, failed to modify kernel mappings",
867 put_balloon_scratch_page();
873 mcs = __xen_mc_entry(
874 sizeof(struct gnttab_unmap_and_replace));
876 unmap_op->host_addr = kmap_op->host_addr;
877 unmap_op->new_addr = scratch_page_address;
878 unmap_op->handle = kmap_op->handle;
880 MULTI_grant_table_op(mcs.mc,
881 GNTTABOP_unmap_and_replace, unmap_op, 1);
883 mcs = __xen_mc_entry(0);
884 MULTI_update_va_mapping(mcs.mc, scratch_page_address,
885 pfn_pte(page_to_pfn(scratch_page),
888 xen_mc_issue(PARAVIRT_LAZY_MMU);
890 kmap_op->host_addr = 0;
891 put_balloon_scratch_page();
895 /* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present
896 * somewhere in this domain, even before being added to the
897 * m2p_override (see comment above in m2p_add_override).
898 * If there are no other entries in the m2p_override corresponding
899 * to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for
900 * the original pfn (the one shared by the frontend): the backend
901 * cannot do any IO on this page anymore because it has been
902 * unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of
903 * the original pfn causes mfn_to_pfn(mfn) to return the frontend
905 mfn &= ~FOREIGN_FRAME_BIT;
906 pfn = mfn_to_pfn_no_overrides(mfn);
907 if (__pfn_to_mfn(pfn) == FOREIGN_FRAME(mfn) &&
908 m2p_find_override(mfn) == NULL)
909 set_phys_to_machine(pfn, mfn);
914 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
915 struct gnttab_map_grant_ref *kmap_ops,
916 struct page **pages, unsigned int count)
921 if (xen_feature(XENFEAT_auto_translated_physmap))
926 paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
927 arch_enter_lazy_mmu_mode();
931 for (i = 0; i < count; i++) {
932 unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i]));
933 unsigned long pfn = page_to_pfn(pages[i]);
935 if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) {
940 set_page_private(pages[i], INVALID_P2M_ENTRY);
941 WARN_ON(!PagePrivate(pages[i]));
942 ClearPagePrivate(pages[i]);
943 set_phys_to_machine(pfn, pages[i]->index);
946 ret = m2p_remove_override(pages[i], &kmap_ops[i], mfn);
953 arch_leave_lazy_mmu_mode();
956 EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);
958 unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn)
960 struct page *p = m2p_find_override(mfn);
961 unsigned long ret = pfn;
964 ret = page_to_pfn(p);
968 EXPORT_SYMBOL_GPL(m2p_find_override_pfn);
970 #ifdef CONFIG_XEN_DEBUG_FS
971 #include <linux/debugfs.h>
973 static int p2m_dump_show(struct seq_file *m, void *v)
975 static const char * const type_name[] = {
976 [P2M_TYPE_IDENTITY] = "identity",
977 [P2M_TYPE_MISSING] = "missing",
978 [P2M_TYPE_PFN] = "pfn",
979 [P2M_TYPE_UNKNOWN] = "abnormal"};
980 unsigned long pfn, first_pfn;
983 prev_type = xen_p2m_elem_type(0);
986 for (pfn = 0; pfn < xen_p2m_size; pfn++) {
987 type = xen_p2m_elem_type(pfn);
988 if (type != prev_type) {
989 seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
990 type_name[prev_type]);
995 seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
996 type_name[prev_type]);
1000 static int p2m_dump_open(struct inode *inode, struct file *filp)
1002 return single_open(filp, p2m_dump_show, NULL);
1005 static const struct file_operations p2m_dump_fops = {
1006 .open = p2m_dump_open,
1008 .llseek = seq_lseek,
1009 .release = single_release,
1012 static struct dentry *d_mmu_debug;
1014 static int __init xen_p2m_debugfs(void)
1016 struct dentry *d_xen = xen_init_debugfs();
1021 d_mmu_debug = debugfs_create_dir("mmu", d_xen);
1023 debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops);
1026 fs_initcall(xen_p2m_debugfs);
1027 #endif /* CONFIG_XEN_DEBUG_FS */