GNU Linux-libre 4.19.286-gnu1
[releases.git] / arch / mips / kvm / mmu.c
1 /*
2  * This file is subject to the terms and conditions of the GNU General Public
3  * License.  See the file "COPYING" in the main directory of this archive
4  * for more details.
5  *
6  * KVM/MIPS MMU handling in the KVM module.
7  *
8  * Copyright (C) 2012  MIPS Technologies, Inc.  All rights reserved.
9  * Authors: Sanjay Lal <sanjayl@kymasys.com>
10  */
11
12 #include <linux/highmem.h>
13 #include <linux/kvm_host.h>
14 #include <linux/uaccess.h>
15 #include <asm/mmu_context.h>
16 #include <asm/pgalloc.h>
17
18 /*
19  * KVM_MMU_CACHE_MIN_PAGES is the number of GPA page table translation levels
20  * for which pages need to be cached.
21  */
22 #if defined(__PAGETABLE_PMD_FOLDED)
23 #define KVM_MMU_CACHE_MIN_PAGES 1
24 #else
25 #define KVM_MMU_CACHE_MIN_PAGES 2
26 #endif
27
28 static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
29                                   int min, int max)
30 {
31         void *page;
32
33         BUG_ON(max > KVM_NR_MEM_OBJS);
34         if (cache->nobjs >= min)
35                 return 0;
36         while (cache->nobjs < max) {
37                 page = (void *)__get_free_page(GFP_KERNEL);
38                 if (!page)
39                         return -ENOMEM;
40                 cache->objects[cache->nobjs++] = page;
41         }
42         return 0;
43 }
44
45 static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
46 {
47         while (mc->nobjs)
48                 free_page((unsigned long)mc->objects[--mc->nobjs]);
49 }
50
51 static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
52 {
53         void *p;
54
55         BUG_ON(!mc || !mc->nobjs);
56         p = mc->objects[--mc->nobjs];
57         return p;
58 }
59
60 void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu)
61 {
62         mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
63 }
64
65 /**
66  * kvm_pgd_init() - Initialise KVM GPA page directory.
67  * @page:       Pointer to page directory (PGD) for KVM GPA.
68  *
69  * Initialise a KVM GPA page directory with pointers to the invalid table, i.e.
70  * representing no mappings. This is similar to pgd_init(), however it
71  * initialises all the page directory pointers, not just the ones corresponding
72  * to the userland address space (since it is for the guest physical address
73  * space rather than a virtual address space).
74  */
75 static void kvm_pgd_init(void *page)
76 {
77         unsigned long *p, *end;
78         unsigned long entry;
79
80 #ifdef __PAGETABLE_PMD_FOLDED
81         entry = (unsigned long)invalid_pte_table;
82 #else
83         entry = (unsigned long)invalid_pmd_table;
84 #endif
85
86         p = (unsigned long *)page;
87         end = p + PTRS_PER_PGD;
88
89         do {
90                 p[0] = entry;
91                 p[1] = entry;
92                 p[2] = entry;
93                 p[3] = entry;
94                 p[4] = entry;
95                 p += 8;
96                 p[-3] = entry;
97                 p[-2] = entry;
98                 p[-1] = entry;
99         } while (p != end);
100 }
101
102 /**
103  * kvm_pgd_alloc() - Allocate and initialise a KVM GPA page directory.
104  *
105  * Allocate a blank KVM GPA page directory (PGD) for representing guest physical
106  * to host physical page mappings.
107  *
108  * Returns:     Pointer to new KVM GPA page directory.
109  *              NULL on allocation failure.
110  */
111 pgd_t *kvm_pgd_alloc(void)
112 {
113         pgd_t *ret;
114
115         ret = (pgd_t *)__get_free_pages(GFP_KERNEL, PGD_ORDER);
116         if (ret)
117                 kvm_pgd_init(ret);
118
119         return ret;
120 }
121
122 /**
123  * kvm_mips_walk_pgd() - Walk page table with optional allocation.
124  * @pgd:        Page directory pointer.
125  * @addr:       Address to index page table using.
126  * @cache:      MMU page cache to allocate new page tables from, or NULL.
127  *
128  * Walk the page tables pointed to by @pgd to find the PTE corresponding to the
129  * address @addr. If page tables don't exist for @addr, they will be created
130  * from the MMU cache if @cache is not NULL.
131  *
132  * Returns:     Pointer to pte_t corresponding to @addr.
133  *              NULL if a page table doesn't exist for @addr and !@cache.
134  *              NULL if a page table allocation failed.
135  */
136 static pte_t *kvm_mips_walk_pgd(pgd_t *pgd, struct kvm_mmu_memory_cache *cache,
137                                 unsigned long addr)
138 {
139         pud_t *pud;
140         pmd_t *pmd;
141
142         pgd += pgd_index(addr);
143         if (pgd_none(*pgd)) {
144                 /* Not used on MIPS yet */
145                 BUG();
146                 return NULL;
147         }
148         pud = pud_offset(pgd, addr);
149         if (pud_none(*pud)) {
150                 pmd_t *new_pmd;
151
152                 if (!cache)
153                         return NULL;
154                 new_pmd = mmu_memory_cache_alloc(cache);
155                 pmd_init((unsigned long)new_pmd,
156                          (unsigned long)invalid_pte_table);
157                 pud_populate(NULL, pud, new_pmd);
158         }
159         pmd = pmd_offset(pud, addr);
160         if (pmd_none(*pmd)) {
161                 pte_t *new_pte;
162
163                 if (!cache)
164                         return NULL;
165                 new_pte = mmu_memory_cache_alloc(cache);
166                 clear_page(new_pte);
167                 pmd_populate_kernel(NULL, pmd, new_pte);
168         }
169         return pte_offset(pmd, addr);
170 }
171
172 /* Caller must hold kvm->mm_lock */
173 static pte_t *kvm_mips_pte_for_gpa(struct kvm *kvm,
174                                    struct kvm_mmu_memory_cache *cache,
175                                    unsigned long addr)
176 {
177         return kvm_mips_walk_pgd(kvm->arch.gpa_mm.pgd, cache, addr);
178 }
179
180 /*
181  * kvm_mips_flush_gpa_{pte,pmd,pud,pgd,pt}.
182  * Flush a range of guest physical address space from the VM's GPA page tables.
183  */
184
185 static bool kvm_mips_flush_gpa_pte(pte_t *pte, unsigned long start_gpa,
186                                    unsigned long end_gpa)
187 {
188         int i_min = __pte_offset(start_gpa);
189         int i_max = __pte_offset(end_gpa);
190         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PTE - 1);
191         int i;
192
193         for (i = i_min; i <= i_max; ++i) {
194                 if (!pte_present(pte[i]))
195                         continue;
196
197                 set_pte(pte + i, __pte(0));
198         }
199         return safe_to_remove;
200 }
201
202 static bool kvm_mips_flush_gpa_pmd(pmd_t *pmd, unsigned long start_gpa,
203                                    unsigned long end_gpa)
204 {
205         pte_t *pte;
206         unsigned long end = ~0ul;
207         int i_min = __pmd_offset(start_gpa);
208         int i_max = __pmd_offset(end_gpa);
209         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PMD - 1);
210         int i;
211
212         for (i = i_min; i <= i_max; ++i, start_gpa = 0) {
213                 if (!pmd_present(pmd[i]))
214                         continue;
215
216                 pte = pte_offset(pmd + i, 0);
217                 if (i == i_max)
218                         end = end_gpa;
219
220                 if (kvm_mips_flush_gpa_pte(pte, start_gpa, end)) {
221                         pmd_clear(pmd + i);
222                         pte_free_kernel(NULL, pte);
223                 } else {
224                         safe_to_remove = false;
225                 }
226         }
227         return safe_to_remove;
228 }
229
230 static bool kvm_mips_flush_gpa_pud(pud_t *pud, unsigned long start_gpa,
231                                    unsigned long end_gpa)
232 {
233         pmd_t *pmd;
234         unsigned long end = ~0ul;
235         int i_min = __pud_offset(start_gpa);
236         int i_max = __pud_offset(end_gpa);
237         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PUD - 1);
238         int i;
239
240         for (i = i_min; i <= i_max; ++i, start_gpa = 0) {
241                 if (!pud_present(pud[i]))
242                         continue;
243
244                 pmd = pmd_offset(pud + i, 0);
245                 if (i == i_max)
246                         end = end_gpa;
247
248                 if (kvm_mips_flush_gpa_pmd(pmd, start_gpa, end)) {
249                         pud_clear(pud + i);
250                         pmd_free(NULL, pmd);
251                 } else {
252                         safe_to_remove = false;
253                 }
254         }
255         return safe_to_remove;
256 }
257
258 static bool kvm_mips_flush_gpa_pgd(pgd_t *pgd, unsigned long start_gpa,
259                                    unsigned long end_gpa)
260 {
261         pud_t *pud;
262         unsigned long end = ~0ul;
263         int i_min = pgd_index(start_gpa);
264         int i_max = pgd_index(end_gpa);
265         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PGD - 1);
266         int i;
267
268         for (i = i_min; i <= i_max; ++i, start_gpa = 0) {
269                 if (!pgd_present(pgd[i]))
270                         continue;
271
272                 pud = pud_offset(pgd + i, 0);
273                 if (i == i_max)
274                         end = end_gpa;
275
276                 if (kvm_mips_flush_gpa_pud(pud, start_gpa, end)) {
277                         pgd_clear(pgd + i);
278                         pud_free(NULL, pud);
279                 } else {
280                         safe_to_remove = false;
281                 }
282         }
283         return safe_to_remove;
284 }
285
286 /**
287  * kvm_mips_flush_gpa_pt() - Flush a range of guest physical addresses.
288  * @kvm:        KVM pointer.
289  * @start_gfn:  Guest frame number of first page in GPA range to flush.
290  * @end_gfn:    Guest frame number of last page in GPA range to flush.
291  *
292  * Flushes a range of GPA mappings from the GPA page tables.
293  *
294  * The caller must hold the @kvm->mmu_lock spinlock.
295  *
296  * Returns:     Whether its safe to remove the top level page directory because
297  *              all lower levels have been removed.
298  */
299 bool kvm_mips_flush_gpa_pt(struct kvm *kvm, gfn_t start_gfn, gfn_t end_gfn)
300 {
301         return kvm_mips_flush_gpa_pgd(kvm->arch.gpa_mm.pgd,
302                                       start_gfn << PAGE_SHIFT,
303                                       end_gfn << PAGE_SHIFT);
304 }
305
306 #define BUILD_PTE_RANGE_OP(name, op)                                    \
307 static int kvm_mips_##name##_pte(pte_t *pte, unsigned long start,       \
308                                  unsigned long end)                     \
309 {                                                                       \
310         int ret = 0;                                                    \
311         int i_min = __pte_offset(start);                                \
312         int i_max = __pte_offset(end);                                  \
313         int i;                                                          \
314         pte_t old, new;                                                 \
315                                                                         \
316         for (i = i_min; i <= i_max; ++i) {                              \
317                 if (!pte_present(pte[i]))                               \
318                         continue;                                       \
319                                                                         \
320                 old = pte[i];                                           \
321                 new = op(old);                                          \
322                 if (pte_val(new) == pte_val(old))                       \
323                         continue;                                       \
324                 set_pte(pte + i, new);                                  \
325                 ret = 1;                                                \
326         }                                                               \
327         return ret;                                                     \
328 }                                                                       \
329                                                                         \
330 /* returns true if anything was done */                                 \
331 static int kvm_mips_##name##_pmd(pmd_t *pmd, unsigned long start,       \
332                                  unsigned long end)                     \
333 {                                                                       \
334         int ret = 0;                                                    \
335         pte_t *pte;                                                     \
336         unsigned long cur_end = ~0ul;                                   \
337         int i_min = __pmd_offset(start);                                \
338         int i_max = __pmd_offset(end);                                  \
339         int i;                                                          \
340                                                                         \
341         for (i = i_min; i <= i_max; ++i, start = 0) {                   \
342                 if (!pmd_present(pmd[i]))                               \
343                         continue;                                       \
344                                                                         \
345                 pte = pte_offset(pmd + i, 0);                           \
346                 if (i == i_max)                                         \
347                         cur_end = end;                                  \
348                                                                         \
349                 ret |= kvm_mips_##name##_pte(pte, start, cur_end);      \
350         }                                                               \
351         return ret;                                                     \
352 }                                                                       \
353                                                                         \
354 static int kvm_mips_##name##_pud(pud_t *pud, unsigned long start,       \
355                                  unsigned long end)                     \
356 {                                                                       \
357         int ret = 0;                                                    \
358         pmd_t *pmd;                                                     \
359         unsigned long cur_end = ~0ul;                                   \
360         int i_min = __pud_offset(start);                                \
361         int i_max = __pud_offset(end);                                  \
362         int i;                                                          \
363                                                                         \
364         for (i = i_min; i <= i_max; ++i, start = 0) {                   \
365                 if (!pud_present(pud[i]))                               \
366                         continue;                                       \
367                                                                         \
368                 pmd = pmd_offset(pud + i, 0);                           \
369                 if (i == i_max)                                         \
370                         cur_end = end;                                  \
371                                                                         \
372                 ret |= kvm_mips_##name##_pmd(pmd, start, cur_end);      \
373         }                                                               \
374         return ret;                                                     \
375 }                                                                       \
376                                                                         \
377 static int kvm_mips_##name##_pgd(pgd_t *pgd, unsigned long start,       \
378                                  unsigned long end)                     \
379 {                                                                       \
380         int ret = 0;                                                    \
381         pud_t *pud;                                                     \
382         unsigned long cur_end = ~0ul;                                   \
383         int i_min = pgd_index(start);                                   \
384         int i_max = pgd_index(end);                                     \
385         int i;                                                          \
386                                                                         \
387         for (i = i_min; i <= i_max; ++i, start = 0) {                   \
388                 if (!pgd_present(pgd[i]))                               \
389                         continue;                                       \
390                                                                         \
391                 pud = pud_offset(pgd + i, 0);                           \
392                 if (i == i_max)                                         \
393                         cur_end = end;                                  \
394                                                                         \
395                 ret |= kvm_mips_##name##_pud(pud, start, cur_end);      \
396         }                                                               \
397         return ret;                                                     \
398 }
399
400 /*
401  * kvm_mips_mkclean_gpa_pt.
402  * Mark a range of guest physical address space clean (writes fault) in the VM's
403  * GPA page table to allow dirty page tracking.
404  */
405
406 BUILD_PTE_RANGE_OP(mkclean, pte_mkclean)
407
408 /**
409  * kvm_mips_mkclean_gpa_pt() - Make a range of guest physical addresses clean.
410  * @kvm:        KVM pointer.
411  * @start_gfn:  Guest frame number of first page in GPA range to flush.
412  * @end_gfn:    Guest frame number of last page in GPA range to flush.
413  *
414  * Make a range of GPA mappings clean so that guest writes will fault and
415  * trigger dirty page logging.
416  *
417  * The caller must hold the @kvm->mmu_lock spinlock.
418  *
419  * Returns:     Whether any GPA mappings were modified, which would require
420  *              derived mappings (GVA page tables & TLB enties) to be
421  *              invalidated.
422  */
423 int kvm_mips_mkclean_gpa_pt(struct kvm *kvm, gfn_t start_gfn, gfn_t end_gfn)
424 {
425         return kvm_mips_mkclean_pgd(kvm->arch.gpa_mm.pgd,
426                                     start_gfn << PAGE_SHIFT,
427                                     end_gfn << PAGE_SHIFT);
428 }
429
430 /**
431  * kvm_arch_mmu_enable_log_dirty_pt_masked() - write protect dirty pages
432  * @kvm:        The KVM pointer
433  * @slot:       The memory slot associated with mask
434  * @gfn_offset: The gfn offset in memory slot
435  * @mask:       The mask of dirty pages at offset 'gfn_offset' in this memory
436  *              slot to be write protected
437  *
438  * Walks bits set in mask write protects the associated pte's. Caller must
439  * acquire @kvm->mmu_lock.
440  */
441 void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
442                 struct kvm_memory_slot *slot,
443                 gfn_t gfn_offset, unsigned long mask)
444 {
445         gfn_t base_gfn = slot->base_gfn + gfn_offset;
446         gfn_t start = base_gfn +  __ffs(mask);
447         gfn_t end = base_gfn + __fls(mask);
448
449         kvm_mips_mkclean_gpa_pt(kvm, start, end);
450 }
451
452 /*
453  * kvm_mips_mkold_gpa_pt.
454  * Mark a range of guest physical address space old (all accesses fault) in the
455  * VM's GPA page table to allow detection of commonly used pages.
456  */
457
458 BUILD_PTE_RANGE_OP(mkold, pte_mkold)
459
460 static int kvm_mips_mkold_gpa_pt(struct kvm *kvm, gfn_t start_gfn,
461                                  gfn_t end_gfn)
462 {
463         return kvm_mips_mkold_pgd(kvm->arch.gpa_mm.pgd,
464                                   start_gfn << PAGE_SHIFT,
465                                   end_gfn << PAGE_SHIFT);
466 }
467
468 static int handle_hva_to_gpa(struct kvm *kvm,
469                              unsigned long start,
470                              unsigned long end,
471                              int (*handler)(struct kvm *kvm, gfn_t gfn,
472                                             gpa_t gfn_end,
473                                             struct kvm_memory_slot *memslot,
474                                             void *data),
475                              void *data)
476 {
477         struct kvm_memslots *slots;
478         struct kvm_memory_slot *memslot;
479         int ret = 0;
480
481         slots = kvm_memslots(kvm);
482
483         /* we only care about the pages that the guest sees */
484         kvm_for_each_memslot(memslot, slots) {
485                 unsigned long hva_start, hva_end;
486                 gfn_t gfn, gfn_end;
487
488                 hva_start = max(start, memslot->userspace_addr);
489                 hva_end = min(end, memslot->userspace_addr +
490                                         (memslot->npages << PAGE_SHIFT));
491                 if (hva_start >= hva_end)
492                         continue;
493
494                 /*
495                  * {gfn(page) | page intersects with [hva_start, hva_end)} =
496                  * {gfn_start, gfn_start+1, ..., gfn_end-1}.
497                  */
498                 gfn = hva_to_gfn_memslot(hva_start, memslot);
499                 gfn_end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, memslot);
500
501                 ret |= handler(kvm, gfn, gfn_end, memslot, data);
502         }
503
504         return ret;
505 }
506
507
508 static int kvm_unmap_hva_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end,
509                                  struct kvm_memory_slot *memslot, void *data)
510 {
511         kvm_mips_flush_gpa_pt(kvm, gfn, gfn_end);
512         return 1;
513 }
514
515 int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end,
516                         bool blockable)
517 {
518         handle_hva_to_gpa(kvm, start, end, &kvm_unmap_hva_handler, NULL);
519
520         kvm_mips_callbacks->flush_shadow_all(kvm);
521         return 0;
522 }
523
524 static int kvm_set_spte_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end,
525                                 struct kvm_memory_slot *memslot, void *data)
526 {
527         gpa_t gpa = gfn << PAGE_SHIFT;
528         pte_t hva_pte = *(pte_t *)data;
529         pte_t *gpa_pte = kvm_mips_pte_for_gpa(kvm, NULL, gpa);
530         pte_t old_pte;
531
532         if (!gpa_pte)
533                 return 0;
534
535         /* Mapping may need adjusting depending on memslot flags */
536         old_pte = *gpa_pte;
537         if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES && !pte_dirty(old_pte))
538                 hva_pte = pte_mkclean(hva_pte);
539         else if (memslot->flags & KVM_MEM_READONLY)
540                 hva_pte = pte_wrprotect(hva_pte);
541
542         set_pte(gpa_pte, hva_pte);
543
544         /* Replacing an absent or old page doesn't need flushes */
545         if (!pte_present(old_pte) || !pte_young(old_pte))
546                 return 0;
547
548         /* Pages swapped, aged, moved, or cleaned require flushes */
549         return !pte_present(hva_pte) ||
550                !pte_young(hva_pte) ||
551                pte_pfn(old_pte) != pte_pfn(hva_pte) ||
552                (pte_dirty(old_pte) && !pte_dirty(hva_pte));
553 }
554
555 void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
556 {
557         unsigned long end = hva + PAGE_SIZE;
558         int ret;
559
560         ret = handle_hva_to_gpa(kvm, hva, end, &kvm_set_spte_handler, &pte);
561         if (ret)
562                 kvm_mips_callbacks->flush_shadow_all(kvm);
563 }
564
565 static int kvm_age_hva_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end,
566                                struct kvm_memory_slot *memslot, void *data)
567 {
568         return kvm_mips_mkold_gpa_pt(kvm, gfn, gfn_end);
569 }
570
571 static int kvm_test_age_hva_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end,
572                                     struct kvm_memory_slot *memslot, void *data)
573 {
574         gpa_t gpa = gfn << PAGE_SHIFT;
575         pte_t *gpa_pte = kvm_mips_pte_for_gpa(kvm, NULL, gpa);
576
577         if (!gpa_pte)
578                 return 0;
579         return pte_young(*gpa_pte);
580 }
581
582 int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end)
583 {
584         return handle_hva_to_gpa(kvm, start, end, kvm_age_hva_handler, NULL);
585 }
586
587 int kvm_test_age_hva(struct kvm *kvm, unsigned long hva)
588 {
589         return handle_hva_to_gpa(kvm, hva, hva, kvm_test_age_hva_handler, NULL);
590 }
591
592 /**
593  * _kvm_mips_map_page_fast() - Fast path GPA fault handler.
594  * @vcpu:               VCPU pointer.
595  * @gpa:                Guest physical address of fault.
596  * @write_fault:        Whether the fault was due to a write.
597  * @out_entry:          New PTE for @gpa (written on success unless NULL).
598  * @out_buddy:          New PTE for @gpa's buddy (written on success unless
599  *                      NULL).
600  *
601  * Perform fast path GPA fault handling, doing all that can be done without
602  * calling into KVM. This handles marking old pages young (for idle page
603  * tracking), and dirtying of clean pages (for dirty page logging).
604  *
605  * Returns:     0 on success, in which case we can update derived mappings and
606  *              resume guest execution.
607  *              -EFAULT on failure due to absent GPA mapping or write to
608  *              read-only page, in which case KVM must be consulted.
609  */
610 static int _kvm_mips_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa,
611                                    bool write_fault,
612                                    pte_t *out_entry, pte_t *out_buddy)
613 {
614         struct kvm *kvm = vcpu->kvm;
615         gfn_t gfn = gpa >> PAGE_SHIFT;
616         pte_t *ptep;
617         kvm_pfn_t pfn = 0;      /* silence bogus GCC warning */
618         bool pfn_valid = false;
619         int ret = 0;
620
621         spin_lock(&kvm->mmu_lock);
622
623         /* Fast path - just check GPA page table for an existing entry */
624         ptep = kvm_mips_pte_for_gpa(kvm, NULL, gpa);
625         if (!ptep || !pte_present(*ptep)) {
626                 ret = -EFAULT;
627                 goto out;
628         }
629
630         /* Track access to pages marked old */
631         if (!pte_young(*ptep)) {
632                 set_pte(ptep, pte_mkyoung(*ptep));
633                 pfn = pte_pfn(*ptep);
634                 pfn_valid = true;
635                 /* call kvm_set_pfn_accessed() after unlock */
636         }
637         if (write_fault && !pte_dirty(*ptep)) {
638                 if (!pte_write(*ptep)) {
639                         ret = -EFAULT;
640                         goto out;
641                 }
642
643                 /* Track dirtying of writeable pages */
644                 set_pte(ptep, pte_mkdirty(*ptep));
645                 pfn = pte_pfn(*ptep);
646                 mark_page_dirty(kvm, gfn);
647                 kvm_set_pfn_dirty(pfn);
648         }
649
650         if (out_entry)
651                 *out_entry = *ptep;
652         if (out_buddy)
653                 *out_buddy = *ptep_buddy(ptep);
654
655 out:
656         spin_unlock(&kvm->mmu_lock);
657         if (pfn_valid)
658                 kvm_set_pfn_accessed(pfn);
659         return ret;
660 }
661
662 /**
663  * kvm_mips_map_page() - Map a guest physical page.
664  * @vcpu:               VCPU pointer.
665  * @gpa:                Guest physical address of fault.
666  * @write_fault:        Whether the fault was due to a write.
667  * @out_entry:          New PTE for @gpa (written on success unless NULL).
668  * @out_buddy:          New PTE for @gpa's buddy (written on success unless
669  *                      NULL).
670  *
671  * Handle GPA faults by creating a new GPA mapping (or updating an existing
672  * one).
673  *
674  * This takes care of marking pages young or dirty (idle/dirty page tracking),
675  * asking KVM for the corresponding PFN, and creating a mapping in the GPA page
676  * tables. Derived mappings (GVA page tables and TLBs) must be handled by the
677  * caller.
678  *
679  * Returns:     0 on success, in which case the caller may use the @out_entry
680  *              and @out_buddy PTEs to update derived mappings and resume guest
681  *              execution.
682  *              -EFAULT if there is no memory region at @gpa or a write was
683  *              attempted to a read-only memory region. This is usually handled
684  *              as an MMIO access.
685  */
686 static int kvm_mips_map_page(struct kvm_vcpu *vcpu, unsigned long gpa,
687                              bool write_fault,
688                              pte_t *out_entry, pte_t *out_buddy)
689 {
690         struct kvm *kvm = vcpu->kvm;
691         struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
692         gfn_t gfn = gpa >> PAGE_SHIFT;
693         int srcu_idx, err;
694         kvm_pfn_t pfn;
695         pte_t *ptep, entry, old_pte;
696         bool writeable;
697         unsigned long prot_bits;
698         unsigned long mmu_seq;
699
700         /* Try the fast path to handle old / clean pages */
701         srcu_idx = srcu_read_lock(&kvm->srcu);
702         err = _kvm_mips_map_page_fast(vcpu, gpa, write_fault, out_entry,
703                                       out_buddy);
704         if (!err)
705                 goto out;
706
707         /* We need a minimum of cached pages ready for page table creation */
708         err = mmu_topup_memory_cache(memcache, KVM_MMU_CACHE_MIN_PAGES,
709                                      KVM_NR_MEM_OBJS);
710         if (err)
711                 goto out;
712
713 retry:
714         /*
715          * Used to check for invalidations in progress, of the pfn that is
716          * returned by pfn_to_pfn_prot below.
717          */
718         mmu_seq = kvm->mmu_notifier_seq;
719         /*
720          * Ensure the read of mmu_notifier_seq isn't reordered with PTE reads in
721          * gfn_to_pfn_prot() (which calls get_user_pages()), so that we don't
722          * risk the page we get a reference to getting unmapped before we have a
723          * chance to grab the mmu_lock without mmu_notifier_retry() noticing.
724          *
725          * This smp_rmb() pairs with the effective smp_wmb() of the combination
726          * of the pte_unmap_unlock() after the PTE is zapped, and the
727          * spin_lock() in kvm_mmu_notifier_invalidate_<page|range_end>() before
728          * mmu_notifier_seq is incremented.
729          */
730         smp_rmb();
731
732         /* Slow path - ask KVM core whether we can access this GPA */
733         pfn = gfn_to_pfn_prot(kvm, gfn, write_fault, &writeable);
734         if (is_error_noslot_pfn(pfn)) {
735                 err = -EFAULT;
736                 goto out;
737         }
738
739         spin_lock(&kvm->mmu_lock);
740         /* Check if an invalidation has taken place since we got pfn */
741         if (mmu_notifier_retry(kvm, mmu_seq)) {
742                 /*
743                  * This can happen when mappings are changed asynchronously, but
744                  * also synchronously if a COW is triggered by
745                  * gfn_to_pfn_prot().
746                  */
747                 spin_unlock(&kvm->mmu_lock);
748                 kvm_release_pfn_clean(pfn);
749                 goto retry;
750         }
751
752         /* Ensure page tables are allocated */
753         ptep = kvm_mips_pte_for_gpa(kvm, memcache, gpa);
754
755         /* Set up the PTE */
756         prot_bits = _PAGE_PRESENT | __READABLE | _page_cachable_default;
757         if (writeable) {
758                 prot_bits |= _PAGE_WRITE;
759                 if (write_fault) {
760                         prot_bits |= __WRITEABLE;
761                         mark_page_dirty(kvm, gfn);
762                         kvm_set_pfn_dirty(pfn);
763                 }
764         }
765         entry = pfn_pte(pfn, __pgprot(prot_bits));
766
767         /* Write the PTE */
768         old_pte = *ptep;
769         set_pte(ptep, entry);
770
771         err = 0;
772         if (out_entry)
773                 *out_entry = *ptep;
774         if (out_buddy)
775                 *out_buddy = *ptep_buddy(ptep);
776
777         spin_unlock(&kvm->mmu_lock);
778         kvm_release_pfn_clean(pfn);
779         kvm_set_pfn_accessed(pfn);
780 out:
781         srcu_read_unlock(&kvm->srcu, srcu_idx);
782         return err;
783 }
784
785 static pte_t *kvm_trap_emul_pte_for_gva(struct kvm_vcpu *vcpu,
786                                         unsigned long addr)
787 {
788         struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
789         pgd_t *pgdp;
790         int ret;
791
792         /* We need a minimum of cached pages ready for page table creation */
793         ret = mmu_topup_memory_cache(memcache, KVM_MMU_CACHE_MIN_PAGES,
794                                      KVM_NR_MEM_OBJS);
795         if (ret)
796                 return NULL;
797
798         if (KVM_GUEST_KERNEL_MODE(vcpu))
799                 pgdp = vcpu->arch.guest_kernel_mm.pgd;
800         else
801                 pgdp = vcpu->arch.guest_user_mm.pgd;
802
803         return kvm_mips_walk_pgd(pgdp, memcache, addr);
804 }
805
806 void kvm_trap_emul_invalidate_gva(struct kvm_vcpu *vcpu, unsigned long addr,
807                                   bool user)
808 {
809         pgd_t *pgdp;
810         pte_t *ptep;
811
812         addr &= PAGE_MASK << 1;
813
814         pgdp = vcpu->arch.guest_kernel_mm.pgd;
815         ptep = kvm_mips_walk_pgd(pgdp, NULL, addr);
816         if (ptep) {
817                 ptep[0] = pfn_pte(0, __pgprot(0));
818                 ptep[1] = pfn_pte(0, __pgprot(0));
819         }
820
821         if (user) {
822                 pgdp = vcpu->arch.guest_user_mm.pgd;
823                 ptep = kvm_mips_walk_pgd(pgdp, NULL, addr);
824                 if (ptep) {
825                         ptep[0] = pfn_pte(0, __pgprot(0));
826                         ptep[1] = pfn_pte(0, __pgprot(0));
827                 }
828         }
829 }
830
831 /*
832  * kvm_mips_flush_gva_{pte,pmd,pud,pgd,pt}.
833  * Flush a range of guest physical address space from the VM's GPA page tables.
834  */
835
836 static bool kvm_mips_flush_gva_pte(pte_t *pte, unsigned long start_gva,
837                                    unsigned long end_gva)
838 {
839         int i_min = __pte_offset(start_gva);
840         int i_max = __pte_offset(end_gva);
841         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PTE - 1);
842         int i;
843
844         /*
845          * There's no freeing to do, so there's no point clearing individual
846          * entries unless only part of the last level page table needs flushing.
847          */
848         if (safe_to_remove)
849                 return true;
850
851         for (i = i_min; i <= i_max; ++i) {
852                 if (!pte_present(pte[i]))
853                         continue;
854
855                 set_pte(pte + i, __pte(0));
856         }
857         return false;
858 }
859
860 static bool kvm_mips_flush_gva_pmd(pmd_t *pmd, unsigned long start_gva,
861                                    unsigned long end_gva)
862 {
863         pte_t *pte;
864         unsigned long end = ~0ul;
865         int i_min = __pmd_offset(start_gva);
866         int i_max = __pmd_offset(end_gva);
867         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PMD - 1);
868         int i;
869
870         for (i = i_min; i <= i_max; ++i, start_gva = 0) {
871                 if (!pmd_present(pmd[i]))
872                         continue;
873
874                 pte = pte_offset(pmd + i, 0);
875                 if (i == i_max)
876                         end = end_gva;
877
878                 if (kvm_mips_flush_gva_pte(pte, start_gva, end)) {
879                         pmd_clear(pmd + i);
880                         pte_free_kernel(NULL, pte);
881                 } else {
882                         safe_to_remove = false;
883                 }
884         }
885         return safe_to_remove;
886 }
887
888 static bool kvm_mips_flush_gva_pud(pud_t *pud, unsigned long start_gva,
889                                    unsigned long end_gva)
890 {
891         pmd_t *pmd;
892         unsigned long end = ~0ul;
893         int i_min = __pud_offset(start_gva);
894         int i_max = __pud_offset(end_gva);
895         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PUD - 1);
896         int i;
897
898         for (i = i_min; i <= i_max; ++i, start_gva = 0) {
899                 if (!pud_present(pud[i]))
900                         continue;
901
902                 pmd = pmd_offset(pud + i, 0);
903                 if (i == i_max)
904                         end = end_gva;
905
906                 if (kvm_mips_flush_gva_pmd(pmd, start_gva, end)) {
907                         pud_clear(pud + i);
908                         pmd_free(NULL, pmd);
909                 } else {
910                         safe_to_remove = false;
911                 }
912         }
913         return safe_to_remove;
914 }
915
916 static bool kvm_mips_flush_gva_pgd(pgd_t *pgd, unsigned long start_gva,
917                                    unsigned long end_gva)
918 {
919         pud_t *pud;
920         unsigned long end = ~0ul;
921         int i_min = pgd_index(start_gva);
922         int i_max = pgd_index(end_gva);
923         bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PGD - 1);
924         int i;
925
926         for (i = i_min; i <= i_max; ++i, start_gva = 0) {
927                 if (!pgd_present(pgd[i]))
928                         continue;
929
930                 pud = pud_offset(pgd + i, 0);
931                 if (i == i_max)
932                         end = end_gva;
933
934                 if (kvm_mips_flush_gva_pud(pud, start_gva, end)) {
935                         pgd_clear(pgd + i);
936                         pud_free(NULL, pud);
937                 } else {
938                         safe_to_remove = false;
939                 }
940         }
941         return safe_to_remove;
942 }
943
944 void kvm_mips_flush_gva_pt(pgd_t *pgd, enum kvm_mips_flush flags)
945 {
946         if (flags & KMF_GPA) {
947                 /* all of guest virtual address space could be affected */
948                 if (flags & KMF_KERN)
949                         /* useg, kseg0, seg2/3 */
950                         kvm_mips_flush_gva_pgd(pgd, 0, 0x7fffffff);
951                 else
952                         /* useg */
953                         kvm_mips_flush_gva_pgd(pgd, 0, 0x3fffffff);
954         } else {
955                 /* useg */
956                 kvm_mips_flush_gva_pgd(pgd, 0, 0x3fffffff);
957
958                 /* kseg2/3 */
959                 if (flags & KMF_KERN)
960                         kvm_mips_flush_gva_pgd(pgd, 0x60000000, 0x7fffffff);
961         }
962 }
963
964 static pte_t kvm_mips_gpa_pte_to_gva_unmapped(pte_t pte)
965 {
966         /*
967          * Don't leak writeable but clean entries from GPA page tables. We don't
968          * want the normal Linux tlbmod handler to handle dirtying when KVM
969          * accesses guest memory.
970          */
971         if (!pte_dirty(pte))
972                 pte = pte_wrprotect(pte);
973
974         return pte;
975 }
976
977 static pte_t kvm_mips_gpa_pte_to_gva_mapped(pte_t pte, long entrylo)
978 {
979         /* Guest EntryLo overrides host EntryLo */
980         if (!(entrylo & ENTRYLO_D))
981                 pte = pte_mkclean(pte);
982
983         return kvm_mips_gpa_pte_to_gva_unmapped(pte);
984 }
985
986 #ifdef CONFIG_KVM_MIPS_VZ
987 int kvm_mips_handle_vz_root_tlb_fault(unsigned long badvaddr,
988                                       struct kvm_vcpu *vcpu,
989                                       bool write_fault)
990 {
991         int ret;
992
993         ret = kvm_mips_map_page(vcpu, badvaddr, write_fault, NULL, NULL);
994         if (ret)
995                 return ret;
996
997         /* Invalidate this entry in the TLB */
998         return kvm_vz_host_tlb_inv(vcpu, badvaddr);
999 }
1000 #endif
1001
1002 /* XXXKYMA: Must be called with interrupts disabled */
1003 int kvm_mips_handle_kseg0_tlb_fault(unsigned long badvaddr,
1004                                     struct kvm_vcpu *vcpu,
1005                                     bool write_fault)
1006 {
1007         unsigned long gpa;
1008         pte_t pte_gpa[2], *ptep_gva;
1009         int idx;
1010
1011         if (KVM_GUEST_KSEGX(badvaddr) != KVM_GUEST_KSEG0) {
1012                 kvm_err("%s: Invalid BadVaddr: %#lx\n", __func__, badvaddr);
1013                 kvm_mips_dump_host_tlbs();
1014                 return -1;
1015         }
1016
1017         /* Get the GPA page table entry */
1018         gpa = KVM_GUEST_CPHYSADDR(badvaddr);
1019         idx = (badvaddr >> PAGE_SHIFT) & 1;
1020         if (kvm_mips_map_page(vcpu, gpa, write_fault, &pte_gpa[idx],
1021                               &pte_gpa[!idx]) < 0)
1022                 return -1;
1023
1024         /* Get the GVA page table entry */
1025         ptep_gva = kvm_trap_emul_pte_for_gva(vcpu, badvaddr & ~PAGE_SIZE);
1026         if (!ptep_gva) {
1027                 kvm_err("No ptep for gva %lx\n", badvaddr);
1028                 return -1;
1029         }
1030
1031         /* Copy a pair of entries from GPA page table to GVA page table */
1032         ptep_gva[0] = kvm_mips_gpa_pte_to_gva_unmapped(pte_gpa[0]);
1033         ptep_gva[1] = kvm_mips_gpa_pte_to_gva_unmapped(pte_gpa[1]);
1034
1035         /* Invalidate this entry in the TLB, guest kernel ASID only */
1036         kvm_mips_host_tlb_inv(vcpu, badvaddr, false, true);
1037         return 0;
1038 }
1039
1040 int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu,
1041                                          struct kvm_mips_tlb *tlb,
1042                                          unsigned long gva,
1043                                          bool write_fault)
1044 {
1045         struct kvm *kvm = vcpu->kvm;
1046         long tlb_lo[2];
1047         pte_t pte_gpa[2], *ptep_buddy, *ptep_gva;
1048         unsigned int idx = TLB_LO_IDX(*tlb, gva);
1049         bool kernel = KVM_GUEST_KERNEL_MODE(vcpu);
1050
1051         tlb_lo[0] = tlb->tlb_lo[0];
1052         tlb_lo[1] = tlb->tlb_lo[1];
1053
1054         /*
1055          * The commpage address must not be mapped to anything else if the guest
1056          * TLB contains entries nearby, or commpage accesses will break.
1057          */
1058         if (!((gva ^ KVM_GUEST_COMMPAGE_ADDR) & VPN2_MASK & (PAGE_MASK << 1)))
1059                 tlb_lo[TLB_LO_IDX(*tlb, KVM_GUEST_COMMPAGE_ADDR)] = 0;
1060
1061         /* Get the GPA page table entry */
1062         if (kvm_mips_map_page(vcpu, mips3_tlbpfn_to_paddr(tlb_lo[idx]),
1063                               write_fault, &pte_gpa[idx], NULL) < 0)
1064                 return -1;
1065
1066         /* And its GVA buddy's GPA page table entry if it also exists */
1067         pte_gpa[!idx] = pfn_pte(0, __pgprot(0));
1068         if (tlb_lo[!idx] & ENTRYLO_V) {
1069                 spin_lock(&kvm->mmu_lock);
1070                 ptep_buddy = kvm_mips_pte_for_gpa(kvm, NULL,
1071                                         mips3_tlbpfn_to_paddr(tlb_lo[!idx]));
1072                 if (ptep_buddy)
1073                         pte_gpa[!idx] = *ptep_buddy;
1074                 spin_unlock(&kvm->mmu_lock);
1075         }
1076
1077         /* Get the GVA page table entry pair */
1078         ptep_gva = kvm_trap_emul_pte_for_gva(vcpu, gva & ~PAGE_SIZE);
1079         if (!ptep_gva) {
1080                 kvm_err("No ptep for gva %lx\n", gva);
1081                 return -1;
1082         }
1083
1084         /* Copy a pair of entries from GPA page table to GVA page table */
1085         ptep_gva[0] = kvm_mips_gpa_pte_to_gva_mapped(pte_gpa[0], tlb_lo[0]);
1086         ptep_gva[1] = kvm_mips_gpa_pte_to_gva_mapped(pte_gpa[1], tlb_lo[1]);
1087
1088         /* Invalidate this entry in the TLB, current guest mode ASID only */
1089         kvm_mips_host_tlb_inv(vcpu, gva, !kernel, kernel);
1090
1091         kvm_debug("@ %#lx tlb_lo0: 0x%08lx tlb_lo1: 0x%08lx\n", vcpu->arch.pc,
1092                   tlb->tlb_lo[0], tlb->tlb_lo[1]);
1093
1094         return 0;
1095 }
1096
1097 int kvm_mips_handle_commpage_tlb_fault(unsigned long badvaddr,
1098                                        struct kvm_vcpu *vcpu)
1099 {
1100         kvm_pfn_t pfn;
1101         pte_t *ptep;
1102
1103         ptep = kvm_trap_emul_pte_for_gva(vcpu, badvaddr);
1104         if (!ptep) {
1105                 kvm_err("No ptep for commpage %lx\n", badvaddr);
1106                 return -1;
1107         }
1108
1109         pfn = PFN_DOWN(virt_to_phys(vcpu->arch.kseg0_commpage));
1110         /* Also set valid and dirty, so refill handler doesn't have to */
1111         *ptep = pte_mkyoung(pte_mkdirty(pfn_pte(pfn, PAGE_SHARED)));
1112
1113         /* Invalidate this entry in the TLB, guest kernel ASID only */
1114         kvm_mips_host_tlb_inv(vcpu, badvaddr, false, true);
1115         return 0;
1116 }
1117
1118 /**
1119  * kvm_mips_migrate_count() - Migrate timer.
1120  * @vcpu:       Virtual CPU.
1121  *
1122  * Migrate CP0_Count hrtimer to the current CPU by cancelling and restarting it
1123  * if it was running prior to being cancelled.
1124  *
1125  * Must be called when the VCPU is migrated to a different CPU to ensure that
1126  * timer expiry during guest execution interrupts the guest and causes the
1127  * interrupt to be delivered in a timely manner.
1128  */
1129 static void kvm_mips_migrate_count(struct kvm_vcpu *vcpu)
1130 {
1131         if (hrtimer_cancel(&vcpu->arch.comparecount_timer))
1132                 hrtimer_restart(&vcpu->arch.comparecount_timer);
1133 }
1134
1135 /* Restore ASID once we are scheduled back after preemption */
1136 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
1137 {
1138         unsigned long flags;
1139
1140         kvm_debug("%s: vcpu %p, cpu: %d\n", __func__, vcpu, cpu);
1141
1142         local_irq_save(flags);
1143
1144         vcpu->cpu = cpu;
1145         if (vcpu->arch.last_sched_cpu != cpu) {
1146                 kvm_debug("[%d->%d]KVM VCPU[%d] switch\n",
1147                           vcpu->arch.last_sched_cpu, cpu, vcpu->vcpu_id);
1148                 /*
1149                  * Migrate the timer interrupt to the current CPU so that it
1150                  * always interrupts the guest and synchronously triggers a
1151                  * guest timer interrupt.
1152                  */
1153                 kvm_mips_migrate_count(vcpu);
1154         }
1155
1156         /* restore guest state to registers */
1157         kvm_mips_callbacks->vcpu_load(vcpu, cpu);
1158
1159         local_irq_restore(flags);
1160 }
1161
1162 /* ASID can change if another task is scheduled during preemption */
1163 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
1164 {
1165         unsigned long flags;
1166         int cpu;
1167
1168         local_irq_save(flags);
1169
1170         cpu = smp_processor_id();
1171         vcpu->arch.last_sched_cpu = cpu;
1172         vcpu->cpu = -1;
1173
1174         /* save guest state in registers */
1175         kvm_mips_callbacks->vcpu_put(vcpu, cpu);
1176
1177         local_irq_restore(flags);
1178 }
1179
1180 /**
1181  * kvm_trap_emul_gva_fault() - Safely attempt to handle a GVA access fault.
1182  * @vcpu:       Virtual CPU.
1183  * @gva:        Guest virtual address to be accessed.
1184  * @write:      True if write attempted (must be dirtied and made writable).
1185  *
1186  * Safely attempt to handle a GVA fault, mapping GVA pages if necessary, and
1187  * dirtying the page if @write so that guest instructions can be modified.
1188  *
1189  * Returns:     KVM_MIPS_MAPPED on success.
1190  *              KVM_MIPS_GVA if bad guest virtual address.
1191  *              KVM_MIPS_GPA if bad guest physical address.
1192  *              KVM_MIPS_TLB if guest TLB not present.
1193  *              KVM_MIPS_TLBINV if guest TLB present but not valid.
1194  *              KVM_MIPS_TLBMOD if guest TLB read only.
1195  */
1196 enum kvm_mips_fault_result kvm_trap_emul_gva_fault(struct kvm_vcpu *vcpu,
1197                                                    unsigned long gva,
1198                                                    bool write)
1199 {
1200         struct mips_coproc *cop0 = vcpu->arch.cop0;
1201         struct kvm_mips_tlb *tlb;
1202         int index;
1203
1204         if (KVM_GUEST_KSEGX(gva) == KVM_GUEST_KSEG0) {
1205                 if (kvm_mips_handle_kseg0_tlb_fault(gva, vcpu, write) < 0)
1206                         return KVM_MIPS_GPA;
1207         } else if ((KVM_GUEST_KSEGX(gva) < KVM_GUEST_KSEG0) ||
1208                    KVM_GUEST_KSEGX(gva) == KVM_GUEST_KSEG23) {
1209                 /* Address should be in the guest TLB */
1210                 index = kvm_mips_guest_tlb_lookup(vcpu, (gva & VPN2_MASK) |
1211                           (kvm_read_c0_guest_entryhi(cop0) & KVM_ENTRYHI_ASID));
1212                 if (index < 0)
1213                         return KVM_MIPS_TLB;
1214                 tlb = &vcpu->arch.guest_tlb[index];
1215
1216                 /* Entry should be valid, and dirty for writes */
1217                 if (!TLB_IS_VALID(*tlb, gva))
1218                         return KVM_MIPS_TLBINV;
1219                 if (write && !TLB_IS_DIRTY(*tlb, gva))
1220                         return KVM_MIPS_TLBMOD;
1221
1222                 if (kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb, gva, write))
1223                         return KVM_MIPS_GPA;
1224         } else {
1225                 return KVM_MIPS_GVA;
1226         }
1227
1228         return KVM_MIPS_MAPPED;
1229 }
1230
1231 int kvm_get_inst(u32 *opc, struct kvm_vcpu *vcpu, u32 *out)
1232 {
1233         int err;
1234
1235         if (WARN(IS_ENABLED(CONFIG_KVM_MIPS_VZ),
1236                  "Expect BadInstr/BadInstrP registers to be used with VZ\n"))
1237                 return -EINVAL;
1238
1239 retry:
1240         kvm_trap_emul_gva_lockless_begin(vcpu);
1241         err = get_user(*out, opc);
1242         kvm_trap_emul_gva_lockless_end(vcpu);
1243
1244         if (unlikely(err)) {
1245                 /*
1246                  * Try to handle the fault, maybe we just raced with a GVA
1247                  * invalidation.
1248                  */
1249                 err = kvm_trap_emul_gva_fault(vcpu, (unsigned long)opc,
1250                                               false);
1251                 if (unlikely(err)) {
1252                         kvm_err("%s: illegal address: %p\n",
1253                                 __func__, opc);
1254                         return -EFAULT;
1255                 }
1256
1257                 /* Hopefully it'll work now */
1258                 goto retry;
1259         }
1260         return 0;
1261 }