Merge tag 'for-linus-4.20a-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel...
[muen/linux.git] / arch / x86 / xen / p2m.c
1 // SPDX-License-Identifier: GPL-2.0
2
3 /*
4  * Xen leaves the responsibility for maintaining p2m mappings to the
5  * guests themselves, but it must also access and update the p2m array
6  * during suspend/resume when all the pages are reallocated.
7  *
8  * The logical flat p2m table is mapped to a linear kernel memory area.
9  * For accesses by Xen a three-level tree linked via mfns only is set up to
10  * allow the address space to be sparse.
11  *
12  *               Xen
13  *                |
14  *          p2m_top_mfn
15  *              /   \
16  * p2m_mid_mfn p2m_mid_mfn
17  *         /           /
18  *  p2m p2m p2m ...
19  *
20  * The p2m_mid_mfn pages are mapped by p2m_top_mfn_p.
21  *
22  * The p2m_top_mfn level is limited to 1 page, so the maximum representable
23  * pseudo-physical address space is:
24  *  P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE pages
25  *
26  * P2M_PER_PAGE depends on the architecture, as a mfn is always
27  * unsigned long (8 bytes on 64-bit, 4 bytes on 32), leading to
28  * 512 and 1024 entries respectively.
29  *
30  * In short, these structures contain the Machine Frame Number (MFN) of the PFN.
31  *
32  * However not all entries are filled with MFNs. Specifically for all other
33  * leaf entries, or for the top  root, or middle one, for which there is a void
34  * entry, we assume it is  "missing". So (for example)
35  *  pfn_to_mfn(0x90909090)=INVALID_P2M_ENTRY.
36  * We have a dedicated page p2m_missing with all entries being
37  * INVALID_P2M_ENTRY. This page may be referenced multiple times in the p2m
38  * list/tree in case there are multiple areas with P2M_PER_PAGE invalid pfns.
39  *
40  * We also have the possibility of setting 1-1 mappings on certain regions, so
41  * that:
42  *  pfn_to_mfn(0xc0000)=0xc0000
43  *
44  * The benefit of this is, that we can assume for non-RAM regions (think
45  * PCI BARs, or ACPI spaces), we can create mappings easily because we
46  * get the PFN value to match the MFN.
47  *
48  * For this to work efficiently we have one new page p2m_identity. All entries
49  * in p2m_identity are set to INVALID_P2M_ENTRY type (Xen toolstack only
50  * recognizes that and MFNs, no other fancy value).
51  *
52  * On lookup we spot that the entry points to p2m_identity and return the
53  * identity value instead of dereferencing and returning INVALID_P2M_ENTRY.
54  * If the entry points to an allocated page, we just proceed as before and
55  * return the PFN. If the PFN has IDENTITY_FRAME_BIT set we unmask that in
56  * appropriate functions (pfn_to_mfn).
57  *
58  * The reason for having the IDENTITY_FRAME_BIT instead of just returning the
59  * PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
60  * non-identity pfn. To protect ourselves against we elect to set (and get) the
61  * IDENTITY_FRAME_BIT on all identity mapped PFNs.
62  */
63
64 #include <linux/init.h>
65 #include <linux/export.h>
66 #include <linux/list.h>
67 #include <linux/hash.h>
68 #include <linux/sched.h>
69 #include <linux/seq_file.h>
70 #include <linux/memblock.h>
71 #include <linux/slab.h>
72 #include <linux/vmalloc.h>
73
74 #include <asm/cache.h>
75 #include <asm/setup.h>
76 #include <linux/uaccess.h>
77
78 #include <asm/xen/page.h>
79 #include <asm/xen/hypercall.h>
80 #include <asm/xen/hypervisor.h>
81 #include <xen/balloon.h>
82 #include <xen/grant_table.h>
83
84 #include "multicalls.h"
85 #include "xen-ops.h"
86
87 #define P2M_MID_PER_PAGE        (PAGE_SIZE / sizeof(unsigned long *))
88 #define P2M_TOP_PER_PAGE        (PAGE_SIZE / sizeof(unsigned long **))
89
90 #define MAX_P2M_PFN     (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE)
91
92 #define PMDS_PER_MID_PAGE       (P2M_MID_PER_PAGE / PTRS_PER_PTE)
93
94 unsigned long *xen_p2m_addr __read_mostly;
95 EXPORT_SYMBOL_GPL(xen_p2m_addr);
96 unsigned long xen_p2m_size __read_mostly;
97 EXPORT_SYMBOL_GPL(xen_p2m_size);
98 unsigned long xen_max_p2m_pfn __read_mostly;
99 EXPORT_SYMBOL_GPL(xen_max_p2m_pfn);
100
101 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
102 #define P2M_LIMIT CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
103 #else
104 #define P2M_LIMIT 0
105 #endif
106
107 static DEFINE_SPINLOCK(p2m_update_lock);
108
109 static unsigned long *p2m_mid_missing_mfn;
110 static unsigned long *p2m_top_mfn;
111 static unsigned long **p2m_top_mfn_p;
112 static unsigned long *p2m_missing;
113 static unsigned long *p2m_identity;
114 static pte_t *p2m_missing_pte;
115 static pte_t *p2m_identity_pte;
116
117 /*
118  * Hint at last populated PFN.
119  *
120  * Used to set HYPERVISOR_shared_info->arch.max_pfn so the toolstack
121  * can avoid scanning the whole P2M (which may be sized to account for
122  * hotplugged memory).
123  */
124 static unsigned long xen_p2m_last_pfn;
125
126 static inline unsigned p2m_top_index(unsigned long pfn)
127 {
128         BUG_ON(pfn >= MAX_P2M_PFN);
129         return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
130 }
131
132 static inline unsigned p2m_mid_index(unsigned long pfn)
133 {
134         return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
135 }
136
137 static inline unsigned p2m_index(unsigned long pfn)
138 {
139         return pfn % P2M_PER_PAGE;
140 }
141
142 static void p2m_top_mfn_init(unsigned long *top)
143 {
144         unsigned i;
145
146         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
147                 top[i] = virt_to_mfn(p2m_mid_missing_mfn);
148 }
149
150 static void p2m_top_mfn_p_init(unsigned long **top)
151 {
152         unsigned i;
153
154         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
155                 top[i] = p2m_mid_missing_mfn;
156 }
157
158 static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf)
159 {
160         unsigned i;
161
162         for (i = 0; i < P2M_MID_PER_PAGE; i++)
163                 mid[i] = virt_to_mfn(leaf);
164 }
165
166 static void p2m_init(unsigned long *p2m)
167 {
168         unsigned i;
169
170         for (i = 0; i < P2M_PER_PAGE; i++)
171                 p2m[i] = INVALID_P2M_ENTRY;
172 }
173
174 static void p2m_init_identity(unsigned long *p2m, unsigned long pfn)
175 {
176         unsigned i;
177
178         for (i = 0; i < P2M_PER_PAGE; i++)
179                 p2m[i] = IDENTITY_FRAME(pfn + i);
180 }
181
182 static void * __ref alloc_p2m_page(void)
183 {
184         if (unlikely(!slab_is_available()))
185                 return memblock_alloc(PAGE_SIZE, PAGE_SIZE);
186
187         return (void *)__get_free_page(GFP_KERNEL);
188 }
189
190 static void __ref free_p2m_page(void *p)
191 {
192         if (unlikely(!slab_is_available())) {
193                 memblock_free((unsigned long)p, PAGE_SIZE);
194                 return;
195         }
196
197         free_page((unsigned long)p);
198 }
199
200 /*
201  * Build the parallel p2m_top_mfn and p2m_mid_mfn structures
202  *
203  * This is called both at boot time, and after resuming from suspend:
204  * - At boot time we're called rather early, and must use alloc_bootmem*()
205  *   to allocate memory.
206  *
207  * - After resume we're called from within stop_machine, but the mfn
208  *   tree should already be completely allocated.
209  */
210 void __ref xen_build_mfn_list_list(void)
211 {
212         unsigned long pfn, mfn;
213         pte_t *ptep;
214         unsigned int level, topidx, mididx;
215         unsigned long *mid_mfn_p;
216
217         if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS)
218                 return;
219
220         /* Pre-initialize p2m_top_mfn to be completely missing */
221         if (p2m_top_mfn == NULL) {
222                 p2m_mid_missing_mfn = alloc_p2m_page();
223                 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
224
225                 p2m_top_mfn_p = alloc_p2m_page();
226                 p2m_top_mfn_p_init(p2m_top_mfn_p);
227
228                 p2m_top_mfn = alloc_p2m_page();
229                 p2m_top_mfn_init(p2m_top_mfn);
230         } else {
231                 /* Reinitialise, mfn's all change after migration */
232                 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
233         }
234
235         for (pfn = 0; pfn < xen_max_p2m_pfn && pfn < MAX_P2M_PFN;
236              pfn += P2M_PER_PAGE) {
237                 topidx = p2m_top_index(pfn);
238                 mididx = p2m_mid_index(pfn);
239
240                 mid_mfn_p = p2m_top_mfn_p[topidx];
241                 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn),
242                                       &level);
243                 BUG_ON(!ptep || level != PG_LEVEL_4K);
244                 mfn = pte_mfn(*ptep);
245                 ptep = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
246
247                 /* Don't bother allocating any mfn mid levels if
248                  * they're just missing, just update the stored mfn,
249                  * since all could have changed over a migrate.
250                  */
251                 if (ptep == p2m_missing_pte || ptep == p2m_identity_pte) {
252                         BUG_ON(mididx);
253                         BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
254                         p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
255                         pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
256                         continue;
257                 }
258
259                 if (mid_mfn_p == p2m_mid_missing_mfn) {
260                         mid_mfn_p = alloc_p2m_page();
261                         p2m_mid_mfn_init(mid_mfn_p, p2m_missing);
262
263                         p2m_top_mfn_p[topidx] = mid_mfn_p;
264                 }
265
266                 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
267                 mid_mfn_p[mididx] = mfn;
268         }
269 }
270
271 void xen_setup_mfn_list_list(void)
272 {
273         BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
274
275         if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS)
276                 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = ~0UL;
277         else
278                 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
279                         virt_to_mfn(p2m_top_mfn);
280         HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn;
281         HYPERVISOR_shared_info->arch.p2m_generation = 0;
282         HYPERVISOR_shared_info->arch.p2m_vaddr = (unsigned long)xen_p2m_addr;
283         HYPERVISOR_shared_info->arch.p2m_cr3 =
284                 xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
285 }
286
287 /* Set up p2m_top to point to the domain-builder provided p2m pages */
288 void __init xen_build_dynamic_phys_to_machine(void)
289 {
290         unsigned long pfn;
291
292         xen_p2m_addr = (unsigned long *)xen_start_info->mfn_list;
293         xen_p2m_size = ALIGN(xen_start_info->nr_pages, P2M_PER_PAGE);
294
295         for (pfn = xen_start_info->nr_pages; pfn < xen_p2m_size; pfn++)
296                 xen_p2m_addr[pfn] = INVALID_P2M_ENTRY;
297
298         xen_max_p2m_pfn = xen_p2m_size;
299 }
300
301 #define P2M_TYPE_IDENTITY       0
302 #define P2M_TYPE_MISSING        1
303 #define P2M_TYPE_PFN            2
304 #define P2M_TYPE_UNKNOWN        3
305
306 static int xen_p2m_elem_type(unsigned long pfn)
307 {
308         unsigned long mfn;
309
310         if (pfn >= xen_p2m_size)
311                 return P2M_TYPE_IDENTITY;
312
313         mfn = xen_p2m_addr[pfn];
314
315         if (mfn == INVALID_P2M_ENTRY)
316                 return P2M_TYPE_MISSING;
317
318         if (mfn & IDENTITY_FRAME_BIT)
319                 return P2M_TYPE_IDENTITY;
320
321         return P2M_TYPE_PFN;
322 }
323
324 static void __init xen_rebuild_p2m_list(unsigned long *p2m)
325 {
326         unsigned int i, chunk;
327         unsigned long pfn;
328         unsigned long *mfns;
329         pte_t *ptep;
330         pmd_t *pmdp;
331         int type;
332
333         p2m_missing = alloc_p2m_page();
334         p2m_init(p2m_missing);
335         p2m_identity = alloc_p2m_page();
336         p2m_init(p2m_identity);
337
338         p2m_missing_pte = alloc_p2m_page();
339         paravirt_alloc_pte(&init_mm, __pa(p2m_missing_pte) >> PAGE_SHIFT);
340         p2m_identity_pte = alloc_p2m_page();
341         paravirt_alloc_pte(&init_mm, __pa(p2m_identity_pte) >> PAGE_SHIFT);
342         for (i = 0; i < PTRS_PER_PTE; i++) {
343                 set_pte(p2m_missing_pte + i,
344                         pfn_pte(PFN_DOWN(__pa(p2m_missing)), PAGE_KERNEL_RO));
345                 set_pte(p2m_identity_pte + i,
346                         pfn_pte(PFN_DOWN(__pa(p2m_identity)), PAGE_KERNEL_RO));
347         }
348
349         for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += chunk) {
350                 /*
351                  * Try to map missing/identity PMDs or p2m-pages if possible.
352                  * We have to respect the structure of the mfn_list_list
353                  * which will be built just afterwards.
354                  * Chunk size to test is one p2m page if we are in the middle
355                  * of a mfn_list_list mid page and the complete mid page area
356                  * if we are at index 0 of the mid page. Please note that a
357                  * mid page might cover more than one PMD, e.g. on 32 bit PAE
358                  * kernels.
359                  */
360                 chunk = (pfn & (P2M_PER_PAGE * P2M_MID_PER_PAGE - 1)) ?
361                         P2M_PER_PAGE : P2M_PER_PAGE * P2M_MID_PER_PAGE;
362
363                 type = xen_p2m_elem_type(pfn);
364                 i = 0;
365                 if (type != P2M_TYPE_PFN)
366                         for (i = 1; i < chunk; i++)
367                                 if (xen_p2m_elem_type(pfn + i) != type)
368                                         break;
369                 if (i < chunk)
370                         /* Reset to minimal chunk size. */
371                         chunk = P2M_PER_PAGE;
372
373                 if (type == P2M_TYPE_PFN || i < chunk) {
374                         /* Use initial p2m page contents. */
375 #ifdef CONFIG_X86_64
376                         mfns = alloc_p2m_page();
377                         copy_page(mfns, xen_p2m_addr + pfn);
378 #else
379                         mfns = xen_p2m_addr + pfn;
380 #endif
381                         ptep = populate_extra_pte((unsigned long)(p2m + pfn));
382                         set_pte(ptep,
383                                 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL));
384                         continue;
385                 }
386
387                 if (chunk == P2M_PER_PAGE) {
388                         /* Map complete missing or identity p2m-page. */
389                         mfns = (type == P2M_TYPE_MISSING) ?
390                                 p2m_missing : p2m_identity;
391                         ptep = populate_extra_pte((unsigned long)(p2m + pfn));
392                         set_pte(ptep,
393                                 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL_RO));
394                         continue;
395                 }
396
397                 /* Complete missing or identity PMD(s) can be mapped. */
398                 ptep = (type == P2M_TYPE_MISSING) ?
399                         p2m_missing_pte : p2m_identity_pte;
400                 for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
401                         pmdp = populate_extra_pmd(
402                                 (unsigned long)(p2m + pfn) + i * PMD_SIZE);
403                         set_pmd(pmdp, __pmd(__pa(ptep) | _KERNPG_TABLE));
404                 }
405         }
406 }
407
408 void __init xen_vmalloc_p2m_tree(void)
409 {
410         static struct vm_struct vm;
411         unsigned long p2m_limit;
412
413         xen_p2m_last_pfn = xen_max_p2m_pfn;
414
415         p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE;
416         vm.flags = VM_ALLOC;
417         vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit),
418                         PMD_SIZE * PMDS_PER_MID_PAGE);
419         vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE);
420         pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size);
421
422         xen_max_p2m_pfn = vm.size / sizeof(unsigned long);
423
424         xen_rebuild_p2m_list(vm.addr);
425
426         xen_p2m_addr = vm.addr;
427         xen_p2m_size = xen_max_p2m_pfn;
428
429         xen_inv_extra_mem();
430 }
431
432 unsigned long get_phys_to_machine(unsigned long pfn)
433 {
434         pte_t *ptep;
435         unsigned int level;
436
437         if (unlikely(pfn >= xen_p2m_size)) {
438                 if (pfn < xen_max_p2m_pfn)
439                         return xen_chk_extra_mem(pfn);
440
441                 return IDENTITY_FRAME(pfn);
442         }
443
444         ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
445         BUG_ON(!ptep || level != PG_LEVEL_4K);
446
447         /*
448          * The INVALID_P2M_ENTRY is filled in both p2m_*identity
449          * and in p2m_*missing, so returning the INVALID_P2M_ENTRY
450          * would be wrong.
451          */
452         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
453                 return IDENTITY_FRAME(pfn);
454
455         return xen_p2m_addr[pfn];
456 }
457 EXPORT_SYMBOL_GPL(get_phys_to_machine);
458
459 /*
460  * Allocate new pmd(s). It is checked whether the old pmd is still in place.
461  * If not, nothing is changed. This is okay as the only reason for allocating
462  * a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual
463  * pmd. In case of PAE/x86-32 there are multiple pmds to allocate!
464  */
465 static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg)
466 {
467         pte_t *ptechk;
468         pte_t *pte_newpg[PMDS_PER_MID_PAGE];
469         pmd_t *pmdp;
470         unsigned int level;
471         unsigned long flags;
472         unsigned long vaddr;
473         int i;
474
475         /* Do all allocations first to bail out in error case. */
476         for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
477                 pte_newpg[i] = alloc_p2m_page();
478                 if (!pte_newpg[i]) {
479                         for (i--; i >= 0; i--)
480                                 free_p2m_page(pte_newpg[i]);
481
482                         return NULL;
483                 }
484         }
485
486         vaddr = addr & ~(PMD_SIZE * PMDS_PER_MID_PAGE - 1);
487
488         for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
489                 copy_page(pte_newpg[i], pte_pg);
490                 paravirt_alloc_pte(&init_mm, __pa(pte_newpg[i]) >> PAGE_SHIFT);
491
492                 pmdp = lookup_pmd_address(vaddr);
493                 BUG_ON(!pmdp);
494
495                 spin_lock_irqsave(&p2m_update_lock, flags);
496
497                 ptechk = lookup_address(vaddr, &level);
498                 if (ptechk == pte_pg) {
499                         HYPERVISOR_shared_info->arch.p2m_generation++;
500                         wmb(); /* Tools are synchronizing via p2m_generation. */
501                         set_pmd(pmdp,
502                                 __pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE));
503                         wmb(); /* Tools are synchronizing via p2m_generation. */
504                         HYPERVISOR_shared_info->arch.p2m_generation++;
505                         pte_newpg[i] = NULL;
506                 }
507
508                 spin_unlock_irqrestore(&p2m_update_lock, flags);
509
510                 if (pte_newpg[i]) {
511                         paravirt_release_pte(__pa(pte_newpg[i]) >> PAGE_SHIFT);
512                         free_p2m_page(pte_newpg[i]);
513                 }
514
515                 vaddr += PMD_SIZE;
516         }
517
518         return lookup_address(addr, &level);
519 }
520
521 /*
522  * Fully allocate the p2m structure for a given pfn.  We need to check
523  * that both the top and mid levels are allocated, and make sure the
524  * parallel mfn tree is kept in sync.  We may race with other cpus, so
525  * the new pages are installed with cmpxchg; if we lose the race then
526  * simply free the page we allocated and use the one that's there.
527  */
528 int xen_alloc_p2m_entry(unsigned long pfn)
529 {
530         unsigned topidx;
531         unsigned long *top_mfn_p, *mid_mfn;
532         pte_t *ptep, *pte_pg;
533         unsigned int level;
534         unsigned long flags;
535         unsigned long addr = (unsigned long)(xen_p2m_addr + pfn);
536         unsigned long p2m_pfn;
537
538         ptep = lookup_address(addr, &level);
539         BUG_ON(!ptep || level != PG_LEVEL_4K);
540         pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
541
542         if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) {
543                 /* PMD level is missing, allocate a new one */
544                 ptep = alloc_p2m_pmd(addr, pte_pg);
545                 if (!ptep)
546                         return -ENOMEM;
547         }
548
549         if (p2m_top_mfn && pfn < MAX_P2M_PFN) {
550                 topidx = p2m_top_index(pfn);
551                 top_mfn_p = &p2m_top_mfn[topidx];
552                 mid_mfn = READ_ONCE(p2m_top_mfn_p[topidx]);
553
554                 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
555
556                 if (mid_mfn == p2m_mid_missing_mfn) {
557                         /* Separately check the mid mfn level */
558                         unsigned long missing_mfn;
559                         unsigned long mid_mfn_mfn;
560                         unsigned long old_mfn;
561
562                         mid_mfn = alloc_p2m_page();
563                         if (!mid_mfn)
564                                 return -ENOMEM;
565
566                         p2m_mid_mfn_init(mid_mfn, p2m_missing);
567
568                         missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
569                         mid_mfn_mfn = virt_to_mfn(mid_mfn);
570                         old_mfn = cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn);
571                         if (old_mfn != missing_mfn) {
572                                 free_p2m_page(mid_mfn);
573                                 mid_mfn = mfn_to_virt(old_mfn);
574                         } else {
575                                 p2m_top_mfn_p[topidx] = mid_mfn;
576                         }
577                 }
578         } else {
579                 mid_mfn = NULL;
580         }
581
582         p2m_pfn = pte_pfn(READ_ONCE(*ptep));
583         if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) ||
584             p2m_pfn == PFN_DOWN(__pa(p2m_missing))) {
585                 /* p2m leaf page is missing */
586                 unsigned long *p2m;
587
588                 p2m = alloc_p2m_page();
589                 if (!p2m)
590                         return -ENOMEM;
591
592                 if (p2m_pfn == PFN_DOWN(__pa(p2m_missing)))
593                         p2m_init(p2m);
594                 else
595                         p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1));
596
597                 spin_lock_irqsave(&p2m_update_lock, flags);
598
599                 if (pte_pfn(*ptep) == p2m_pfn) {
600                         HYPERVISOR_shared_info->arch.p2m_generation++;
601                         wmb(); /* Tools are synchronizing via p2m_generation. */
602                         set_pte(ptep,
603                                 pfn_pte(PFN_DOWN(__pa(p2m)), PAGE_KERNEL));
604                         wmb(); /* Tools are synchronizing via p2m_generation. */
605                         HYPERVISOR_shared_info->arch.p2m_generation++;
606                         if (mid_mfn)
607                                 mid_mfn[p2m_mid_index(pfn)] = virt_to_mfn(p2m);
608                         p2m = NULL;
609                 }
610
611                 spin_unlock_irqrestore(&p2m_update_lock, flags);
612
613                 if (p2m)
614                         free_p2m_page(p2m);
615         }
616
617         /* Expanded the p2m? */
618         if (pfn > xen_p2m_last_pfn) {
619                 xen_p2m_last_pfn = pfn;
620                 HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn;
621         }
622
623         return 0;
624 }
625 EXPORT_SYMBOL(xen_alloc_p2m_entry);
626
627 unsigned long __init set_phys_range_identity(unsigned long pfn_s,
628                                       unsigned long pfn_e)
629 {
630         unsigned long pfn;
631
632         if (unlikely(pfn_s >= xen_p2m_size))
633                 return 0;
634
635         if (pfn_s > pfn_e)
636                 return 0;
637
638         if (pfn_e > xen_p2m_size)
639                 pfn_e = xen_p2m_size;
640
641         for (pfn = pfn_s; pfn < pfn_e; pfn++)
642                 xen_p2m_addr[pfn] = IDENTITY_FRAME(pfn);
643
644         return pfn - pfn_s;
645 }
646
647 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
648 {
649         pte_t *ptep;
650         unsigned int level;
651
652         if (unlikely(pfn >= xen_p2m_size)) {
653                 BUG_ON(mfn != INVALID_P2M_ENTRY);
654                 return true;
655         }
656
657         /*
658          * The interface requires atomic updates on p2m elements.
659          * xen_safe_write_ulong() is using an atomic store via asm().
660          */
661         if (likely(!xen_safe_write_ulong(xen_p2m_addr + pfn, mfn)))
662                 return true;
663
664         ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
665         BUG_ON(!ptep || level != PG_LEVEL_4K);
666
667         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_missing)))
668                 return mfn == INVALID_P2M_ENTRY;
669
670         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
671                 return mfn == IDENTITY_FRAME(pfn);
672
673         return false;
674 }
675
676 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
677 {
678         if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
679                 int ret;
680
681                 ret = xen_alloc_p2m_entry(pfn);
682                 if (ret < 0)
683                         return false;
684
685                 return __set_phys_to_machine(pfn, mfn);
686         }
687
688         return true;
689 }
690
691 int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
692                             struct gnttab_map_grant_ref *kmap_ops,
693                             struct page **pages, unsigned int count)
694 {
695         int i, ret = 0;
696         pte_t *pte;
697
698         if (xen_feature(XENFEAT_auto_translated_physmap))
699                 return 0;
700
701         if (kmap_ops) {
702                 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
703                                                 kmap_ops, count);
704                 if (ret)
705                         goto out;
706         }
707
708         for (i = 0; i < count; i++) {
709                 unsigned long mfn, pfn;
710
711                 /* Do not add to override if the map failed. */
712                 if (map_ops[i].status)
713                         continue;
714
715                 if (map_ops[i].flags & GNTMAP_contains_pte) {
716                         pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
717                                 (map_ops[i].host_addr & ~PAGE_MASK));
718                         mfn = pte_mfn(*pte);
719                 } else {
720                         mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
721                 }
722                 pfn = page_to_pfn(pages[i]);
723
724                 WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned");
725
726                 if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
727                         ret = -ENOMEM;
728                         goto out;
729                 }
730         }
731
732 out:
733         return ret;
734 }
735 EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping);
736
737 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
738                               struct gnttab_unmap_grant_ref *kunmap_ops,
739                               struct page **pages, unsigned int count)
740 {
741         int i, ret = 0;
742
743         if (xen_feature(XENFEAT_auto_translated_physmap))
744                 return 0;
745
746         for (i = 0; i < count; i++) {
747                 unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i]));
748                 unsigned long pfn = page_to_pfn(pages[i]);
749
750                 if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) {
751                         ret = -EINVAL;
752                         goto out;
753                 }
754
755                 set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
756         }
757         if (kunmap_ops)
758                 ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
759                                                 kunmap_ops, count);
760 out:
761         return ret;
762 }
763 EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);
764
765 #ifdef CONFIG_XEN_DEBUG_FS
766 #include <linux/debugfs.h>
767 #include "debugfs.h"
768 static int p2m_dump_show(struct seq_file *m, void *v)
769 {
770         static const char * const type_name[] = {
771                                 [P2M_TYPE_IDENTITY] = "identity",
772                                 [P2M_TYPE_MISSING] = "missing",
773                                 [P2M_TYPE_PFN] = "pfn",
774                                 [P2M_TYPE_UNKNOWN] = "abnormal"};
775         unsigned long pfn, first_pfn;
776         int type, prev_type;
777
778         prev_type = xen_p2m_elem_type(0);
779         first_pfn = 0;
780
781         for (pfn = 0; pfn < xen_p2m_size; pfn++) {
782                 type = xen_p2m_elem_type(pfn);
783                 if (type != prev_type) {
784                         seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
785                                    type_name[prev_type]);
786                         prev_type = type;
787                         first_pfn = pfn;
788                 }
789         }
790         seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
791                    type_name[prev_type]);
792         return 0;
793 }
794
795 static int p2m_dump_open(struct inode *inode, struct file *filp)
796 {
797         return single_open(filp, p2m_dump_show, NULL);
798 }
799
800 static const struct file_operations p2m_dump_fops = {
801         .open           = p2m_dump_open,
802         .read           = seq_read,
803         .llseek         = seq_lseek,
804         .release        = single_release,
805 };
806
807 static struct dentry *d_mmu_debug;
808
809 static int __init xen_p2m_debugfs(void)
810 {
811         struct dentry *d_xen = xen_init_debugfs();
812
813         if (d_xen == NULL)
814                 return -ENOMEM;
815
816         d_mmu_debug = debugfs_create_dir("mmu", d_xen);
817
818         debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops);
819         return 0;
820 }
821 fs_initcall(xen_p2m_debugfs);
822 #endif /* CONFIG_XEN_DEBUG_FS */