GNU Linux-libre 4.14.266-gnu1
[releases.git] / arch / x86 / xen / p2m.c
1 /*
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.
5  *
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.
9  *
10  *               Xen
11  *                |
12  *          p2m_top_mfn
13  *              /   \
14  * p2m_mid_mfn p2m_mid_mfn
15  *         /           /
16  *  p2m p2m p2m ...
17  *
18  * The p2m_mid_mfn pages are mapped by p2m_top_mfn_p.
19  *
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
23  *
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.
27  *
28  * In short, these structures contain the Machine Frame Number (MFN) of the PFN.
29  *
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.
37  *
38  * We also have the possibility of setting 1-1 mappings on certain regions, so
39  * that:
40  *  pfn_to_mfn(0xc0000)=0xc0000
41  *
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.
45  *
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).
49  *
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).
55  *
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.
60  */
61
62 #include <linux/init.h>
63 #include <linux/export.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>
70 #include <linux/vmalloc.h>
71
72 #include <asm/cache.h>
73 #include <asm/setup.h>
74 #include <linux/uaccess.h>
75
76 #include <asm/xen/page.h>
77 #include <asm/xen/hypercall.h>
78 #include <asm/xen/hypervisor.h>
79 #include <xen/balloon.h>
80 #include <xen/grant_table.h>
81
82 #include "multicalls.h"
83 #include "xen-ops.h"
84
85 #define P2M_MID_PER_PAGE        (PAGE_SIZE / sizeof(unsigned long *))
86 #define P2M_TOP_PER_PAGE        (PAGE_SIZE / sizeof(unsigned long **))
87
88 #define MAX_P2M_PFN     (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE)
89
90 #define PMDS_PER_MID_PAGE       (P2M_MID_PER_PAGE / PTRS_PER_PTE)
91
92 unsigned long *xen_p2m_addr __read_mostly;
93 EXPORT_SYMBOL_GPL(xen_p2m_addr);
94 unsigned long xen_p2m_size __read_mostly;
95 EXPORT_SYMBOL_GPL(xen_p2m_size);
96 unsigned long xen_max_p2m_pfn __read_mostly;
97 EXPORT_SYMBOL_GPL(xen_max_p2m_pfn);
98
99 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
100 #define P2M_LIMIT CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
101 #else
102 #define P2M_LIMIT 0
103 #endif
104
105 static DEFINE_SPINLOCK(p2m_update_lock);
106
107 static unsigned long *p2m_mid_missing_mfn;
108 static unsigned long *p2m_top_mfn;
109 static unsigned long **p2m_top_mfn_p;
110 static unsigned long *p2m_missing;
111 static unsigned long *p2m_identity;
112 static pte_t *p2m_missing_pte;
113 static pte_t *p2m_identity_pte;
114
115 /*
116  * Hint at last populated PFN.
117  *
118  * Used to set HYPERVISOR_shared_info->arch.max_pfn so the toolstack
119  * can avoid scanning the whole P2M (which may be sized to account for
120  * hotplugged memory).
121  */
122 static unsigned long xen_p2m_last_pfn;
123
124 static inline unsigned p2m_top_index(unsigned long pfn)
125 {
126         BUG_ON(pfn >= MAX_P2M_PFN);
127         return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
128 }
129
130 static inline unsigned p2m_mid_index(unsigned long pfn)
131 {
132         return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
133 }
134
135 static inline unsigned p2m_index(unsigned long pfn)
136 {
137         return pfn % P2M_PER_PAGE;
138 }
139
140 static void p2m_top_mfn_init(unsigned long *top)
141 {
142         unsigned i;
143
144         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
145                 top[i] = virt_to_mfn(p2m_mid_missing_mfn);
146 }
147
148 static void p2m_top_mfn_p_init(unsigned long **top)
149 {
150         unsigned i;
151
152         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
153                 top[i] = p2m_mid_missing_mfn;
154 }
155
156 static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf)
157 {
158         unsigned i;
159
160         for (i = 0; i < P2M_MID_PER_PAGE; i++)
161                 mid[i] = virt_to_mfn(leaf);
162 }
163
164 static void p2m_init(unsigned long *p2m)
165 {
166         unsigned i;
167
168         for (i = 0; i < P2M_PER_PAGE; i++)
169                 p2m[i] = INVALID_P2M_ENTRY;
170 }
171
172 static void p2m_init_identity(unsigned long *p2m, unsigned long pfn)
173 {
174         unsigned i;
175
176         for (i = 0; i < P2M_PER_PAGE; i++)
177                 p2m[i] = IDENTITY_FRAME(pfn + i);
178 }
179
180 static void * __ref alloc_p2m_page(void)
181 {
182         if (unlikely(!slab_is_available()))
183                 return alloc_bootmem_align(PAGE_SIZE, PAGE_SIZE);
184
185         return (void *)__get_free_page(GFP_KERNEL);
186 }
187
188 static void __ref free_p2m_page(void *p)
189 {
190         if (unlikely(!slab_is_available())) {
191                 free_bootmem((unsigned long)p, PAGE_SIZE);
192                 return;
193         }
194
195         free_page((unsigned long)p);
196 }
197
198 /*
199  * Build the parallel p2m_top_mfn and p2m_mid_mfn structures
200  *
201  * This is called both at boot time, and after resuming from suspend:
202  * - At boot time we're called rather early, and must use alloc_bootmem*()
203  *   to allocate memory.
204  *
205  * - After resume we're called from within stop_machine, but the mfn
206  *   tree should already be completely allocated.
207  */
208 void __ref xen_build_mfn_list_list(void)
209 {
210         unsigned long pfn, mfn;
211         pte_t *ptep;
212         unsigned int level, topidx, mididx;
213         unsigned long *mid_mfn_p;
214
215         if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS)
216                 return;
217
218         /* Pre-initialize p2m_top_mfn to be completely missing */
219         if (p2m_top_mfn == NULL) {
220                 p2m_mid_missing_mfn = alloc_p2m_page();
221                 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
222
223                 p2m_top_mfn_p = alloc_p2m_page();
224                 p2m_top_mfn_p_init(p2m_top_mfn_p);
225
226                 p2m_top_mfn = alloc_p2m_page();
227                 p2m_top_mfn_init(p2m_top_mfn);
228         } else {
229                 /* Reinitialise, mfn's all change after migration */
230                 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
231         }
232
233         for (pfn = 0; pfn < xen_max_p2m_pfn && pfn < MAX_P2M_PFN;
234              pfn += P2M_PER_PAGE) {
235                 topidx = p2m_top_index(pfn);
236                 mididx = p2m_mid_index(pfn);
237
238                 mid_mfn_p = p2m_top_mfn_p[topidx];
239                 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn),
240                                       &level);
241                 BUG_ON(!ptep || level != PG_LEVEL_4K);
242                 mfn = pte_mfn(*ptep);
243                 ptep = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
244
245                 /* Don't bother allocating any mfn mid levels if
246                  * they're just missing, just update the stored mfn,
247                  * since all could have changed over a migrate.
248                  */
249                 if (ptep == p2m_missing_pte || ptep == p2m_identity_pte) {
250                         BUG_ON(mididx);
251                         BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
252                         p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
253                         pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
254                         continue;
255                 }
256
257                 if (mid_mfn_p == p2m_mid_missing_mfn) {
258                         mid_mfn_p = alloc_p2m_page();
259                         p2m_mid_mfn_init(mid_mfn_p, p2m_missing);
260
261                         p2m_top_mfn_p[topidx] = mid_mfn_p;
262                 }
263
264                 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
265                 mid_mfn_p[mididx] = mfn;
266         }
267 }
268
269 void xen_setup_mfn_list_list(void)
270 {
271         BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
272
273         if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS)
274                 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = ~0UL;
275         else
276                 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
277                         virt_to_mfn(p2m_top_mfn);
278         HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn;
279         HYPERVISOR_shared_info->arch.p2m_generation = 0;
280         HYPERVISOR_shared_info->arch.p2m_vaddr = (unsigned long)xen_p2m_addr;
281         HYPERVISOR_shared_info->arch.p2m_cr3 =
282                 xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
283 }
284
285 /* Set up p2m_top to point to the domain-builder provided p2m pages */
286 void __init xen_build_dynamic_phys_to_machine(void)
287 {
288         unsigned long pfn;
289
290         xen_p2m_addr = (unsigned long *)xen_start_info->mfn_list;
291         xen_p2m_size = ALIGN(xen_start_info->nr_pages, P2M_PER_PAGE);
292
293         for (pfn = xen_start_info->nr_pages; pfn < xen_p2m_size; pfn++)
294                 xen_p2m_addr[pfn] = INVALID_P2M_ENTRY;
295
296         xen_max_p2m_pfn = xen_p2m_size;
297 }
298
299 #define P2M_TYPE_IDENTITY       0
300 #define P2M_TYPE_MISSING        1
301 #define P2M_TYPE_PFN            2
302 #define P2M_TYPE_UNKNOWN        3
303
304 static int xen_p2m_elem_type(unsigned long pfn)
305 {
306         unsigned long mfn;
307
308         if (pfn >= xen_p2m_size)
309                 return P2M_TYPE_IDENTITY;
310
311         mfn = xen_p2m_addr[pfn];
312
313         if (mfn == INVALID_P2M_ENTRY)
314                 return P2M_TYPE_MISSING;
315
316         if (mfn & IDENTITY_FRAME_BIT)
317                 return P2M_TYPE_IDENTITY;
318
319         return P2M_TYPE_PFN;
320 }
321
322 static void __init xen_rebuild_p2m_list(unsigned long *p2m)
323 {
324         unsigned int i, chunk;
325         unsigned long pfn;
326         unsigned long *mfns;
327         pte_t *ptep;
328         pmd_t *pmdp;
329         int type;
330
331         p2m_missing = alloc_p2m_page();
332         p2m_init(p2m_missing);
333         p2m_identity = alloc_p2m_page();
334         p2m_init(p2m_identity);
335
336         p2m_missing_pte = alloc_p2m_page();
337         paravirt_alloc_pte(&init_mm, __pa(p2m_missing_pte) >> PAGE_SHIFT);
338         p2m_identity_pte = alloc_p2m_page();
339         paravirt_alloc_pte(&init_mm, __pa(p2m_identity_pte) >> PAGE_SHIFT);
340         for (i = 0; i < PTRS_PER_PTE; i++) {
341                 set_pte(p2m_missing_pte + i,
342                         pfn_pte(PFN_DOWN(__pa(p2m_missing)), PAGE_KERNEL_RO));
343                 set_pte(p2m_identity_pte + i,
344                         pfn_pte(PFN_DOWN(__pa(p2m_identity)), PAGE_KERNEL_RO));
345         }
346
347         for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += chunk) {
348                 /*
349                  * Try to map missing/identity PMDs or p2m-pages if possible.
350                  * We have to respect the structure of the mfn_list_list
351                  * which will be built just afterwards.
352                  * Chunk size to test is one p2m page if we are in the middle
353                  * of a mfn_list_list mid page and the complete mid page area
354                  * if we are at index 0 of the mid page. Please note that a
355                  * mid page might cover more than one PMD, e.g. on 32 bit PAE
356                  * kernels.
357                  */
358                 chunk = (pfn & (P2M_PER_PAGE * P2M_MID_PER_PAGE - 1)) ?
359                         P2M_PER_PAGE : P2M_PER_PAGE * P2M_MID_PER_PAGE;
360
361                 type = xen_p2m_elem_type(pfn);
362                 i = 0;
363                 if (type != P2M_TYPE_PFN)
364                         for (i = 1; i < chunk; i++)
365                                 if (xen_p2m_elem_type(pfn + i) != type)
366                                         break;
367                 if (i < chunk)
368                         /* Reset to minimal chunk size. */
369                         chunk = P2M_PER_PAGE;
370
371                 if (type == P2M_TYPE_PFN || i < chunk) {
372                         /* Use initial p2m page contents. */
373 #ifdef CONFIG_X86_64
374                         mfns = alloc_p2m_page();
375                         copy_page(mfns, xen_p2m_addr + pfn);
376 #else
377                         mfns = xen_p2m_addr + pfn;
378 #endif
379                         ptep = populate_extra_pte((unsigned long)(p2m + pfn));
380                         set_pte(ptep,
381                                 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL));
382                         continue;
383                 }
384
385                 if (chunk == P2M_PER_PAGE) {
386                         /* Map complete missing or identity p2m-page. */
387                         mfns = (type == P2M_TYPE_MISSING) ?
388                                 p2m_missing : p2m_identity;
389                         ptep = populate_extra_pte((unsigned long)(p2m + pfn));
390                         set_pte(ptep,
391                                 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL_RO));
392                         continue;
393                 }
394
395                 /* Complete missing or identity PMD(s) can be mapped. */
396                 ptep = (type == P2M_TYPE_MISSING) ?
397                         p2m_missing_pte : p2m_identity_pte;
398                 for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
399                         pmdp = populate_extra_pmd(
400                                 (unsigned long)(p2m + pfn) + i * PMD_SIZE);
401                         set_pmd(pmdp, __pmd(__pa(ptep) | _KERNPG_TABLE));
402                 }
403         }
404 }
405
406 void __init xen_vmalloc_p2m_tree(void)
407 {
408         static struct vm_struct vm;
409         unsigned long p2m_limit;
410
411         xen_p2m_last_pfn = xen_max_p2m_pfn;
412
413         p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE;
414         vm.flags = VM_ALLOC;
415         vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit),
416                         PMD_SIZE * PMDS_PER_MID_PAGE);
417         vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE);
418         pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size);
419
420         xen_max_p2m_pfn = vm.size / sizeof(unsigned long);
421
422         xen_rebuild_p2m_list(vm.addr);
423
424         xen_p2m_addr = vm.addr;
425         xen_p2m_size = xen_max_p2m_pfn;
426
427         xen_inv_extra_mem();
428 }
429
430 unsigned long get_phys_to_machine(unsigned long pfn)
431 {
432         pte_t *ptep;
433         unsigned int level;
434
435         if (unlikely(pfn >= xen_p2m_size)) {
436                 if (pfn < xen_max_p2m_pfn)
437                         return xen_chk_extra_mem(pfn);
438
439                 return IDENTITY_FRAME(pfn);
440         }
441
442         ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
443         BUG_ON(!ptep || level != PG_LEVEL_4K);
444
445         /*
446          * The INVALID_P2M_ENTRY is filled in both p2m_*identity
447          * and in p2m_*missing, so returning the INVALID_P2M_ENTRY
448          * would be wrong.
449          */
450         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
451                 return IDENTITY_FRAME(pfn);
452
453         return xen_p2m_addr[pfn];
454 }
455 EXPORT_SYMBOL_GPL(get_phys_to_machine);
456
457 /*
458  * Allocate new pmd(s). It is checked whether the old pmd is still in place.
459  * If not, nothing is changed. This is okay as the only reason for allocating
460  * a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual
461  * pmd. In case of PAE/x86-32 there are multiple pmds to allocate!
462  */
463 static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg)
464 {
465         pte_t *ptechk;
466         pte_t *pte_newpg[PMDS_PER_MID_PAGE];
467         pmd_t *pmdp;
468         unsigned int level;
469         unsigned long flags;
470         unsigned long vaddr;
471         int i;
472
473         /* Do all allocations first to bail out in error case. */
474         for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
475                 pte_newpg[i] = alloc_p2m_page();
476                 if (!pte_newpg[i]) {
477                         for (i--; i >= 0; i--)
478                                 free_p2m_page(pte_newpg[i]);
479
480                         return NULL;
481                 }
482         }
483
484         vaddr = addr & ~(PMD_SIZE * PMDS_PER_MID_PAGE - 1);
485
486         for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
487                 copy_page(pte_newpg[i], pte_pg);
488                 paravirt_alloc_pte(&init_mm, __pa(pte_newpg[i]) >> PAGE_SHIFT);
489
490                 pmdp = lookup_pmd_address(vaddr);
491                 BUG_ON(!pmdp);
492
493                 spin_lock_irqsave(&p2m_update_lock, flags);
494
495                 ptechk = lookup_address(vaddr, &level);
496                 if (ptechk == pte_pg) {
497                         HYPERVISOR_shared_info->arch.p2m_generation++;
498                         wmb(); /* Tools are synchronizing via p2m_generation. */
499                         set_pmd(pmdp,
500                                 __pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE));
501                         wmb(); /* Tools are synchronizing via p2m_generation. */
502                         HYPERVISOR_shared_info->arch.p2m_generation++;
503                         pte_newpg[i] = NULL;
504                 }
505
506                 spin_unlock_irqrestore(&p2m_update_lock, flags);
507
508                 if (pte_newpg[i]) {
509                         paravirt_release_pte(__pa(pte_newpg[i]) >> PAGE_SHIFT);
510                         free_p2m_page(pte_newpg[i]);
511                 }
512
513                 vaddr += PMD_SIZE;
514         }
515
516         return lookup_address(addr, &level);
517 }
518
519 /*
520  * Fully allocate the p2m structure for a given pfn.  We need to check
521  * that both the top and mid levels are allocated, and make sure the
522  * parallel mfn tree is kept in sync.  We may race with other cpus, so
523  * the new pages are installed with cmpxchg; if we lose the race then
524  * simply free the page we allocated and use the one that's there.
525  */
526 int xen_alloc_p2m_entry(unsigned long pfn)
527 {
528         unsigned topidx;
529         unsigned long *top_mfn_p, *mid_mfn;
530         pte_t *ptep, *pte_pg;
531         unsigned int level;
532         unsigned long flags;
533         unsigned long addr = (unsigned long)(xen_p2m_addr + pfn);
534         unsigned long p2m_pfn;
535
536         ptep = lookup_address(addr, &level);
537         BUG_ON(!ptep || level != PG_LEVEL_4K);
538         pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
539
540         if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) {
541                 /* PMD level is missing, allocate a new one */
542                 ptep = alloc_p2m_pmd(addr, pte_pg);
543                 if (!ptep)
544                         return -ENOMEM;
545         }
546
547         if (p2m_top_mfn && pfn < MAX_P2M_PFN) {
548                 topidx = p2m_top_index(pfn);
549                 top_mfn_p = &p2m_top_mfn[topidx];
550                 mid_mfn = ACCESS_ONCE(p2m_top_mfn_p[topidx]);
551
552                 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
553
554                 if (mid_mfn == p2m_mid_missing_mfn) {
555                         /* Separately check the mid mfn level */
556                         unsigned long missing_mfn;
557                         unsigned long mid_mfn_mfn;
558                         unsigned long old_mfn;
559
560                         mid_mfn = alloc_p2m_page();
561                         if (!mid_mfn)
562                                 return -ENOMEM;
563
564                         p2m_mid_mfn_init(mid_mfn, p2m_missing);
565
566                         missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
567                         mid_mfn_mfn = virt_to_mfn(mid_mfn);
568                         old_mfn = cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn);
569                         if (old_mfn != missing_mfn) {
570                                 free_p2m_page(mid_mfn);
571                                 mid_mfn = mfn_to_virt(old_mfn);
572                         } else {
573                                 p2m_top_mfn_p[topidx] = mid_mfn;
574                         }
575                 }
576         } else {
577                 mid_mfn = NULL;
578         }
579
580         p2m_pfn = pte_pfn(READ_ONCE(*ptep));
581         if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) ||
582             p2m_pfn == PFN_DOWN(__pa(p2m_missing))) {
583                 /* p2m leaf page is missing */
584                 unsigned long *p2m;
585
586                 p2m = alloc_p2m_page();
587                 if (!p2m)
588                         return -ENOMEM;
589
590                 if (p2m_pfn == PFN_DOWN(__pa(p2m_missing)))
591                         p2m_init(p2m);
592                 else
593                         p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1));
594
595                 spin_lock_irqsave(&p2m_update_lock, flags);
596
597                 if (pte_pfn(*ptep) == p2m_pfn) {
598                         HYPERVISOR_shared_info->arch.p2m_generation++;
599                         wmb(); /* Tools are synchronizing via p2m_generation. */
600                         set_pte(ptep,
601                                 pfn_pte(PFN_DOWN(__pa(p2m)), PAGE_KERNEL));
602                         wmb(); /* Tools are synchronizing via p2m_generation. */
603                         HYPERVISOR_shared_info->arch.p2m_generation++;
604                         if (mid_mfn)
605                                 mid_mfn[p2m_mid_index(pfn)] = virt_to_mfn(p2m);
606                         p2m = NULL;
607                 }
608
609                 spin_unlock_irqrestore(&p2m_update_lock, flags);
610
611                 if (p2m)
612                         free_p2m_page(p2m);
613         }
614
615         /* Expanded the p2m? */
616         if (pfn >= xen_p2m_last_pfn) {
617                 xen_p2m_last_pfn = ALIGN(pfn + 1, P2M_PER_PAGE);
618                 HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn;
619         }
620
621         return 0;
622 }
623 EXPORT_SYMBOL(xen_alloc_p2m_entry);
624
625 unsigned long __init set_phys_range_identity(unsigned long pfn_s,
626                                       unsigned long pfn_e)
627 {
628         unsigned long pfn;
629
630         if (unlikely(pfn_s >= xen_p2m_size))
631                 return 0;
632
633         if (pfn_s > pfn_e)
634                 return 0;
635
636         if (pfn_e > xen_p2m_size)
637                 pfn_e = xen_p2m_size;
638
639         for (pfn = pfn_s; pfn < pfn_e; pfn++)
640                 xen_p2m_addr[pfn] = IDENTITY_FRAME(pfn);
641
642         return pfn - pfn_s;
643 }
644
645 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
646 {
647         pte_t *ptep;
648         unsigned int level;
649
650         if (unlikely(pfn >= xen_p2m_size)) {
651                 BUG_ON(mfn != INVALID_P2M_ENTRY);
652                 return true;
653         }
654
655         /*
656          * The interface requires atomic updates on p2m elements.
657          * xen_safe_write_ulong() is using __put_user which does an atomic
658          * store via asm().
659          */
660         if (likely(!xen_safe_write_ulong(xen_p2m_addr + pfn, mfn)))
661                 return true;
662
663         ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
664         BUG_ON(!ptep || level != PG_LEVEL_4K);
665
666         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_missing)))
667                 return mfn == INVALID_P2M_ENTRY;
668
669         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
670                 return mfn == IDENTITY_FRAME(pfn);
671
672         return false;
673 }
674
675 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
676 {
677         if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
678                 int ret;
679
680                 ret = xen_alloc_p2m_entry(pfn);
681                 if (ret < 0)
682                         return false;
683
684                 return __set_phys_to_machine(pfn, mfn);
685         }
686
687         return true;
688 }
689
690 int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
691                             struct gnttab_map_grant_ref *kmap_ops,
692                             struct page **pages, unsigned int count)
693 {
694         int i, ret = 0;
695         pte_t *pte;
696
697         if (xen_feature(XENFEAT_auto_translated_physmap))
698                 return 0;
699
700         if (kmap_ops) {
701                 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
702                                                 kmap_ops, count);
703                 if (ret)
704                         goto out;
705         }
706
707         for (i = 0; i < count; i++) {
708                 unsigned long mfn, pfn;
709                 struct gnttab_unmap_grant_ref unmap[2];
710                 int rc;
711
712                 /* Do not add to override if the map failed. */
713                 if (map_ops[i].status != GNTST_okay ||
714                     (kmap_ops && kmap_ops[i].status != GNTST_okay))
715                         continue;
716
717                 if (map_ops[i].flags & GNTMAP_contains_pte) {
718                         pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
719                                 (map_ops[i].host_addr & ~PAGE_MASK));
720                         mfn = pte_mfn(*pte);
721                 } else {
722                         mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
723                 }
724                 pfn = page_to_pfn(pages[i]);
725
726                 WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned");
727
728                 if (likely(set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))
729                         continue;
730
731                 /*
732                  * Signal an error for this slot. This in turn requires
733                  * immediate unmapping.
734                  */
735                 map_ops[i].status = GNTST_general_error;
736                 unmap[0].host_addr = map_ops[i].host_addr,
737                 unmap[0].handle = map_ops[i].handle;
738                 map_ops[i].handle = ~0;
739                 if (map_ops[i].flags & GNTMAP_device_map)
740                         unmap[0].dev_bus_addr = map_ops[i].dev_bus_addr;
741                 else
742                         unmap[0].dev_bus_addr = 0;
743
744                 if (kmap_ops) {
745                         kmap_ops[i].status = GNTST_general_error;
746                         unmap[1].host_addr = kmap_ops[i].host_addr,
747                         unmap[1].handle = kmap_ops[i].handle;
748                         kmap_ops[i].handle = ~0;
749                         if (kmap_ops[i].flags & GNTMAP_device_map)
750                                 unmap[1].dev_bus_addr = kmap_ops[i].dev_bus_addr;
751                         else
752                                 unmap[1].dev_bus_addr = 0;
753                 }
754
755                 /*
756                  * Pre-populate both status fields, to be recognizable in
757                  * the log message below.
758                  */
759                 unmap[0].status = 1;
760                 unmap[1].status = 1;
761
762                 rc = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
763                                                unmap, 1 + !!kmap_ops);
764                 if (rc || unmap[0].status != GNTST_okay ||
765                     unmap[1].status != GNTST_okay)
766                         pr_err_once("gnttab unmap failed: rc=%d st0=%d st1=%d\n",
767                                     rc, unmap[0].status, unmap[1].status);
768         }
769
770 out:
771         return ret;
772 }
773 EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping);
774
775 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
776                               struct gnttab_unmap_grant_ref *kunmap_ops,
777                               struct page **pages, unsigned int count)
778 {
779         int i, ret = 0;
780
781         if (xen_feature(XENFEAT_auto_translated_physmap))
782                 return 0;
783
784         for (i = 0; i < count; i++) {
785                 unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i]));
786                 unsigned long pfn = page_to_pfn(pages[i]);
787
788                 if (mfn != INVALID_P2M_ENTRY && (mfn & FOREIGN_FRAME_BIT))
789                         set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
790                 else
791                         ret = -EINVAL;
792         }
793         if (kunmap_ops)
794                 ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
795                                                 kunmap_ops, count) ?: ret;
796
797         return ret;
798 }
799 EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);
800
801 #ifdef CONFIG_XEN_DEBUG_FS
802 #include <linux/debugfs.h>
803 #include "debugfs.h"
804 static int p2m_dump_show(struct seq_file *m, void *v)
805 {
806         static const char * const type_name[] = {
807                                 [P2M_TYPE_IDENTITY] = "identity",
808                                 [P2M_TYPE_MISSING] = "missing",
809                                 [P2M_TYPE_PFN] = "pfn",
810                                 [P2M_TYPE_UNKNOWN] = "abnormal"};
811         unsigned long pfn, first_pfn;
812         int type, prev_type;
813
814         prev_type = xen_p2m_elem_type(0);
815         first_pfn = 0;
816
817         for (pfn = 0; pfn < xen_p2m_size; pfn++) {
818                 type = xen_p2m_elem_type(pfn);
819                 if (type != prev_type) {
820                         seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
821                                    type_name[prev_type]);
822                         prev_type = type;
823                         first_pfn = pfn;
824                 }
825         }
826         seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
827                    type_name[prev_type]);
828         return 0;
829 }
830
831 static int p2m_dump_open(struct inode *inode, struct file *filp)
832 {
833         return single_open(filp, p2m_dump_show, NULL);
834 }
835
836 static const struct file_operations p2m_dump_fops = {
837         .open           = p2m_dump_open,
838         .read           = seq_read,
839         .llseek         = seq_lseek,
840         .release        = single_release,
841 };
842
843 static struct dentry *d_mmu_debug;
844
845 static int __init xen_p2m_debugfs(void)
846 {
847         struct dentry *d_xen = xen_init_debugfs();
848
849         if (d_xen == NULL)
850                 return -ENOMEM;
851
852         d_mmu_debug = debugfs_create_dir("mmu", d_xen);
853
854         debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops);
855         return 0;
856 }
857 fs_initcall(xen_p2m_debugfs);
858 #endif /* CONFIG_XEN_DEBUG_FS */