[PATCH] KVM: MMU: Page table write flood protection
[linux-2.6.git] / drivers / kvm / mmu.c
1 /*
2  * Kernel-based Virtual Machine driver for Linux
3  *
4  * This module enables machines with Intel VT-x extensions to run virtual
5  * machines without emulation or binary translation.
6  *
7  * MMU support
8  *
9  * Copyright (C) 2006 Qumranet, Inc.
10  *
11  * Authors:
12  *   Yaniv Kamay  <yaniv@qumranet.com>
13  *   Avi Kivity   <avi@qumranet.com>
14  *
15  * This work is licensed under the terms of the GNU GPL, version 2.  See
16  * the COPYING file in the top-level directory.
17  *
18  */
19 #include <linux/types.h>
20 #include <linux/string.h>
21 #include <asm/page.h>
22 #include <linux/mm.h>
23 #include <linux/highmem.h>
24 #include <linux/module.h>
25
26 #include "vmx.h"
27 #include "kvm.h"
28
29 #define pgprintk(x...) do { printk(x); } while (0)
30 #define rmap_printk(x...) do { printk(x); } while (0)
31
32 #define ASSERT(x)                                                       \
33         if (!(x)) {                                                     \
34                 printk(KERN_WARNING "assertion failed %s:%d: %s\n",     \
35                        __FILE__, __LINE__, #x);                         \
36         }
37
38 #define PT64_PT_BITS 9
39 #define PT64_ENT_PER_PAGE (1 << PT64_PT_BITS)
40 #define PT32_PT_BITS 10
41 #define PT32_ENT_PER_PAGE (1 << PT32_PT_BITS)
42
43 #define PT_WRITABLE_SHIFT 1
44
45 #define PT_PRESENT_MASK (1ULL << 0)
46 #define PT_WRITABLE_MASK (1ULL << PT_WRITABLE_SHIFT)
47 #define PT_USER_MASK (1ULL << 2)
48 #define PT_PWT_MASK (1ULL << 3)
49 #define PT_PCD_MASK (1ULL << 4)
50 #define PT_ACCESSED_MASK (1ULL << 5)
51 #define PT_DIRTY_MASK (1ULL << 6)
52 #define PT_PAGE_SIZE_MASK (1ULL << 7)
53 #define PT_PAT_MASK (1ULL << 7)
54 #define PT_GLOBAL_MASK (1ULL << 8)
55 #define PT64_NX_MASK (1ULL << 63)
56
57 #define PT_PAT_SHIFT 7
58 #define PT_DIR_PAT_SHIFT 12
59 #define PT_DIR_PAT_MASK (1ULL << PT_DIR_PAT_SHIFT)
60
61 #define PT32_DIR_PSE36_SIZE 4
62 #define PT32_DIR_PSE36_SHIFT 13
63 #define PT32_DIR_PSE36_MASK (((1ULL << PT32_DIR_PSE36_SIZE) - 1) << PT32_DIR_PSE36_SHIFT)
64
65
66 #define PT32_PTE_COPY_MASK \
67         (PT_PRESENT_MASK | PT_ACCESSED_MASK | PT_DIRTY_MASK | PT_GLOBAL_MASK)
68
69 #define PT64_PTE_COPY_MASK (PT64_NX_MASK | PT32_PTE_COPY_MASK)
70
71 #define PT_FIRST_AVAIL_BITS_SHIFT 9
72 #define PT64_SECOND_AVAIL_BITS_SHIFT 52
73
74 #define PT_SHADOW_PS_MARK (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
75 #define PT_SHADOW_IO_MARK (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
76
77 #define PT_SHADOW_WRITABLE_SHIFT (PT_FIRST_AVAIL_BITS_SHIFT + 1)
78 #define PT_SHADOW_WRITABLE_MASK (1ULL << PT_SHADOW_WRITABLE_SHIFT)
79
80 #define PT_SHADOW_USER_SHIFT (PT_SHADOW_WRITABLE_SHIFT + 1)
81 #define PT_SHADOW_USER_MASK (1ULL << (PT_SHADOW_USER_SHIFT))
82
83 #define PT_SHADOW_BITS_OFFSET (PT_SHADOW_WRITABLE_SHIFT - PT_WRITABLE_SHIFT)
84
85 #define VALID_PAGE(x) ((x) != INVALID_PAGE)
86
87 #define PT64_LEVEL_BITS 9
88
89 #define PT64_LEVEL_SHIFT(level) \
90                 ( PAGE_SHIFT + (level - 1) * PT64_LEVEL_BITS )
91
92 #define PT64_LEVEL_MASK(level) \
93                 (((1ULL << PT64_LEVEL_BITS) - 1) << PT64_LEVEL_SHIFT(level))
94
95 #define PT64_INDEX(address, level)\
96         (((address) >> PT64_LEVEL_SHIFT(level)) & ((1 << PT64_LEVEL_BITS) - 1))
97
98
99 #define PT32_LEVEL_BITS 10
100
101 #define PT32_LEVEL_SHIFT(level) \
102                 ( PAGE_SHIFT + (level - 1) * PT32_LEVEL_BITS )
103
104 #define PT32_LEVEL_MASK(level) \
105                 (((1ULL << PT32_LEVEL_BITS) - 1) << PT32_LEVEL_SHIFT(level))
106
107 #define PT32_INDEX(address, level)\
108         (((address) >> PT32_LEVEL_SHIFT(level)) & ((1 << PT32_LEVEL_BITS) - 1))
109
110
111 #define PT64_BASE_ADDR_MASK (((1ULL << 52) - 1) & PAGE_MASK)
112 #define PT64_DIR_BASE_ADDR_MASK \
113         (PT64_BASE_ADDR_MASK & ~((1ULL << (PAGE_SHIFT + PT64_LEVEL_BITS)) - 1))
114
115 #define PT32_BASE_ADDR_MASK PAGE_MASK
116 #define PT32_DIR_BASE_ADDR_MASK \
117         (PAGE_MASK & ~((1ULL << (PAGE_SHIFT + PT32_LEVEL_BITS)) - 1))
118
119
120 #define PFERR_PRESENT_MASK (1U << 0)
121 #define PFERR_WRITE_MASK (1U << 1)
122 #define PFERR_USER_MASK (1U << 2)
123
124 #define PT64_ROOT_LEVEL 4
125 #define PT32_ROOT_LEVEL 2
126 #define PT32E_ROOT_LEVEL 3
127
128 #define PT_DIRECTORY_LEVEL 2
129 #define PT_PAGE_TABLE_LEVEL 1
130
131 #define RMAP_EXT 4
132
133 struct kvm_rmap_desc {
134         u64 *shadow_ptes[RMAP_EXT];
135         struct kvm_rmap_desc *more;
136 };
137
138 static int is_write_protection(struct kvm_vcpu *vcpu)
139 {
140         return vcpu->cr0 & CR0_WP_MASK;
141 }
142
143 static int is_cpuid_PSE36(void)
144 {
145         return 1;
146 }
147
148 static int is_present_pte(unsigned long pte)
149 {
150         return pte & PT_PRESENT_MASK;
151 }
152
153 static int is_writeble_pte(unsigned long pte)
154 {
155         return pte & PT_WRITABLE_MASK;
156 }
157
158 static int is_io_pte(unsigned long pte)
159 {
160         return pte & PT_SHADOW_IO_MARK;
161 }
162
163 static int is_rmap_pte(u64 pte)
164 {
165         return (pte & (PT_WRITABLE_MASK | PT_PRESENT_MASK))
166                 == (PT_WRITABLE_MASK | PT_PRESENT_MASK);
167 }
168
169 /*
170  * Reverse mapping data structures:
171  *
172  * If page->private bit zero is zero, then page->private points to the
173  * shadow page table entry that points to page_address(page).
174  *
175  * If page->private bit zero is one, (then page->private & ~1) points
176  * to a struct kvm_rmap_desc containing more mappings.
177  */
178 static void rmap_add(struct kvm *kvm, u64 *spte)
179 {
180         struct page *page;
181         struct kvm_rmap_desc *desc;
182         int i;
183
184         if (!is_rmap_pte(*spte))
185                 return;
186         page = pfn_to_page((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT);
187         if (!page->private) {
188                 rmap_printk("rmap_add: %p %llx 0->1\n", spte, *spte);
189                 page->private = (unsigned long)spte;
190         } else if (!(page->private & 1)) {
191                 rmap_printk("rmap_add: %p %llx 1->many\n", spte, *spte);
192                 desc = kzalloc(sizeof *desc, GFP_NOWAIT);
193                 if (!desc)
194                         BUG(); /* FIXME: return error */
195                 desc->shadow_ptes[0] = (u64 *)page->private;
196                 desc->shadow_ptes[1] = spte;
197                 page->private = (unsigned long)desc | 1;
198         } else {
199                 rmap_printk("rmap_add: %p %llx many->many\n", spte, *spte);
200                 desc = (struct kvm_rmap_desc *)(page->private & ~1ul);
201                 while (desc->shadow_ptes[RMAP_EXT-1] && desc->more)
202                         desc = desc->more;
203                 if (desc->shadow_ptes[RMAP_EXT-1]) {
204                         desc->more = kzalloc(sizeof *desc->more, GFP_NOWAIT);
205                         if (!desc->more)
206                                 BUG(); /* FIXME: return error */
207                         desc = desc->more;
208                 }
209                 for (i = 0; desc->shadow_ptes[i]; ++i)
210                         ;
211                 desc->shadow_ptes[i] = spte;
212         }
213 }
214
215 static void rmap_desc_remove_entry(struct page *page,
216                                    struct kvm_rmap_desc *desc,
217                                    int i,
218                                    struct kvm_rmap_desc *prev_desc)
219 {
220         int j;
221
222         for (j = RMAP_EXT - 1; !desc->shadow_ptes[j] && j > i; --j)
223                 ;
224         desc->shadow_ptes[i] = desc->shadow_ptes[j];
225         desc->shadow_ptes[j] = 0;
226         if (j != 0)
227                 return;
228         if (!prev_desc && !desc->more)
229                 page->private = (unsigned long)desc->shadow_ptes[0];
230         else
231                 if (prev_desc)
232                         prev_desc->more = desc->more;
233                 else
234                         page->private = (unsigned long)desc->more | 1;
235         kfree(desc);
236 }
237
238 static void rmap_remove(struct kvm *kvm, u64 *spte)
239 {
240         struct page *page;
241         struct kvm_rmap_desc *desc;
242         struct kvm_rmap_desc *prev_desc;
243         int i;
244
245         if (!is_rmap_pte(*spte))
246                 return;
247         page = pfn_to_page((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT);
248         if (!page->private) {
249                 printk(KERN_ERR "rmap_remove: %p %llx 0->BUG\n", spte, *spte);
250                 BUG();
251         } else if (!(page->private & 1)) {
252                 rmap_printk("rmap_remove:  %p %llx 1->0\n", spte, *spte);
253                 if ((u64 *)page->private != spte) {
254                         printk(KERN_ERR "rmap_remove:  %p %llx 1->BUG\n",
255                                spte, *spte);
256                         BUG();
257                 }
258                 page->private = 0;
259         } else {
260                 rmap_printk("rmap_remove:  %p %llx many->many\n", spte, *spte);
261                 desc = (struct kvm_rmap_desc *)(page->private & ~1ul);
262                 prev_desc = NULL;
263                 while (desc) {
264                         for (i = 0; i < RMAP_EXT && desc->shadow_ptes[i]; ++i)
265                                 if (desc->shadow_ptes[i] == spte) {
266                                         rmap_desc_remove_entry(page, desc, i,
267                                                                prev_desc);
268                                         return;
269                                 }
270                         prev_desc = desc;
271                         desc = desc->more;
272                 }
273                 BUG();
274         }
275 }
276
277 static void rmap_write_protect(struct kvm *kvm, u64 gfn)
278 {
279         struct page *page;
280         struct kvm_memory_slot *slot;
281         struct kvm_rmap_desc *desc;
282         u64 *spte;
283
284         slot = gfn_to_memslot(kvm, gfn);
285         BUG_ON(!slot);
286         page = gfn_to_page(slot, gfn);
287
288         while (page->private) {
289                 if (!(page->private & 1))
290                         spte = (u64 *)page->private;
291                 else {
292                         desc = (struct kvm_rmap_desc *)(page->private & ~1ul);
293                         spte = desc->shadow_ptes[0];
294                 }
295                 BUG_ON(!spte);
296                 BUG_ON((*spte & PT64_BASE_ADDR_MASK) !=
297                        page_to_pfn(page) << PAGE_SHIFT);
298                 BUG_ON(!(*spte & PT_PRESENT_MASK));
299                 BUG_ON(!(*spte & PT_WRITABLE_MASK));
300                 rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);
301                 rmap_remove(kvm, spte);
302                 *spte &= ~(u64)PT_WRITABLE_MASK;
303         }
304 }
305
306 static int is_empty_shadow_page(hpa_t page_hpa)
307 {
308         u64 *pos;
309         u64 *end;
310
311         for (pos = __va(page_hpa), end = pos + PAGE_SIZE / sizeof(u64);
312                       pos != end; pos++)
313                 if (*pos != 0) {
314                         printk(KERN_ERR "%s: %p %llx\n", __FUNCTION__,
315                                pos, *pos);
316                         return 0;
317                 }
318         return 1;
319 }
320
321 static void kvm_mmu_free_page(struct kvm_vcpu *vcpu, hpa_t page_hpa)
322 {
323         struct kvm_mmu_page *page_head = page_header(page_hpa);
324
325         ASSERT(is_empty_shadow_page(page_hpa));
326         list_del(&page_head->link);
327         page_head->page_hpa = page_hpa;
328         list_add(&page_head->link, &vcpu->free_pages);
329         ++vcpu->kvm->n_free_mmu_pages;
330 }
331
332 static unsigned kvm_page_table_hashfn(gfn_t gfn)
333 {
334         return gfn;
335 }
336
337 static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu,
338                                                u64 *parent_pte)
339 {
340         struct kvm_mmu_page *page;
341
342         if (list_empty(&vcpu->free_pages))
343                 return NULL;
344
345         page = list_entry(vcpu->free_pages.next, struct kvm_mmu_page, link);
346         list_del(&page->link);
347         list_add(&page->link, &vcpu->kvm->active_mmu_pages);
348         ASSERT(is_empty_shadow_page(page->page_hpa));
349         page->slot_bitmap = 0;
350         page->global = 1;
351         page->multimapped = 0;
352         page->parent_pte = parent_pte;
353         --vcpu->kvm->n_free_mmu_pages;
354         return page;
355 }
356
357 static void mmu_page_add_parent_pte(struct kvm_mmu_page *page, u64 *parent_pte)
358 {
359         struct kvm_pte_chain *pte_chain;
360         struct hlist_node *node;
361         int i;
362
363         if (!parent_pte)
364                 return;
365         if (!page->multimapped) {
366                 u64 *old = page->parent_pte;
367
368                 if (!old) {
369                         page->parent_pte = parent_pte;
370                         return;
371                 }
372                 page->multimapped = 1;
373                 pte_chain = kzalloc(sizeof(struct kvm_pte_chain), GFP_NOWAIT);
374                 BUG_ON(!pte_chain);
375                 INIT_HLIST_HEAD(&page->parent_ptes);
376                 hlist_add_head(&pte_chain->link, &page->parent_ptes);
377                 pte_chain->parent_ptes[0] = old;
378         }
379         hlist_for_each_entry(pte_chain, node, &page->parent_ptes, link) {
380                 if (pte_chain->parent_ptes[NR_PTE_CHAIN_ENTRIES-1])
381                         continue;
382                 for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i)
383                         if (!pte_chain->parent_ptes[i]) {
384                                 pte_chain->parent_ptes[i] = parent_pte;
385                                 return;
386                         }
387         }
388         pte_chain = kzalloc(sizeof(struct kvm_pte_chain), GFP_NOWAIT);
389         BUG_ON(!pte_chain);
390         hlist_add_head(&pte_chain->link, &page->parent_ptes);
391         pte_chain->parent_ptes[0] = parent_pte;
392 }
393
394 static void mmu_page_remove_parent_pte(struct kvm_mmu_page *page,
395                                        u64 *parent_pte)
396 {
397         struct kvm_pte_chain *pte_chain;
398         struct hlist_node *node;
399         int i;
400
401         if (!page->multimapped) {
402                 BUG_ON(page->parent_pte != parent_pte);
403                 page->parent_pte = NULL;
404                 return;
405         }
406         hlist_for_each_entry(pte_chain, node, &page->parent_ptes, link)
407                 for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i) {
408                         if (!pte_chain->parent_ptes[i])
409                                 break;
410                         if (pte_chain->parent_ptes[i] != parent_pte)
411                                 continue;
412                         while (i + 1 < NR_PTE_CHAIN_ENTRIES
413                                 && pte_chain->parent_ptes[i + 1]) {
414                                 pte_chain->parent_ptes[i]
415                                         = pte_chain->parent_ptes[i + 1];
416                                 ++i;
417                         }
418                         pte_chain->parent_ptes[i] = NULL;
419                         if (i == 0) {
420                                 hlist_del(&pte_chain->link);
421                                 kfree(pte_chain);
422                                 if (hlist_empty(&page->parent_ptes)) {
423                                         page->multimapped = 0;
424                                         page->parent_pte = NULL;
425                                 }
426                         }
427                         return;
428                 }
429         BUG();
430 }
431
432 static struct kvm_mmu_page *kvm_mmu_lookup_page(struct kvm_vcpu *vcpu,
433                                                 gfn_t gfn)
434 {
435         unsigned index;
436         struct hlist_head *bucket;
437         struct kvm_mmu_page *page;
438         struct hlist_node *node;
439
440         pgprintk("%s: looking for gfn %lx\n", __FUNCTION__, gfn);
441         index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
442         bucket = &vcpu->kvm->mmu_page_hash[index];
443         hlist_for_each_entry(page, node, bucket, hash_link)
444                 if (page->gfn == gfn && !page->role.metaphysical) {
445                         pgprintk("%s: found role %x\n",
446                                  __FUNCTION__, page->role.word);
447                         return page;
448                 }
449         return NULL;
450 }
451
452 static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
453                                              gfn_t gfn,
454                                              gva_t gaddr,
455                                              unsigned level,
456                                              int metaphysical,
457                                              u64 *parent_pte)
458 {
459         union kvm_mmu_page_role role;
460         unsigned index;
461         unsigned quadrant;
462         struct hlist_head *bucket;
463         struct kvm_mmu_page *page;
464         struct hlist_node *node;
465
466         role.word = 0;
467         role.glevels = vcpu->mmu.root_level;
468         role.level = level;
469         role.metaphysical = metaphysical;
470         if (vcpu->mmu.root_level <= PT32_ROOT_LEVEL) {
471                 quadrant = gaddr >> (PAGE_SHIFT + (PT64_PT_BITS * level));
472                 quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;
473                 role.quadrant = quadrant;
474         }
475         pgprintk("%s: looking gfn %lx role %x\n", __FUNCTION__,
476                  gfn, role.word);
477         index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
478         bucket = &vcpu->kvm->mmu_page_hash[index];
479         hlist_for_each_entry(page, node, bucket, hash_link)
480                 if (page->gfn == gfn && page->role.word == role.word) {
481                         mmu_page_add_parent_pte(page, parent_pte);
482                         pgprintk("%s: found\n", __FUNCTION__);
483                         return page;
484                 }
485         page = kvm_mmu_alloc_page(vcpu, parent_pte);
486         if (!page)
487                 return page;
488         pgprintk("%s: adding gfn %lx role %x\n", __FUNCTION__, gfn, role.word);
489         page->gfn = gfn;
490         page->role = role;
491         hlist_add_head(&page->hash_link, bucket);
492         if (!metaphysical)
493                 rmap_write_protect(vcpu->kvm, gfn);
494         return page;
495 }
496
497 static void kvm_mmu_page_unlink_children(struct kvm_vcpu *vcpu,
498                                          struct kvm_mmu_page *page)
499 {
500         unsigned i;
501         u64 *pt;
502         u64 ent;
503
504         pt = __va(page->page_hpa);
505
506         if (page->role.level == PT_PAGE_TABLE_LEVEL) {
507                 for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
508                         if (pt[i] & PT_PRESENT_MASK)
509                                 rmap_remove(vcpu->kvm, &pt[i]);
510                         pt[i] = 0;
511                 }
512                 return;
513         }
514
515         for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
516                 ent = pt[i];
517
518                 pt[i] = 0;
519                 if (!(ent & PT_PRESENT_MASK))
520                         continue;
521                 ent &= PT64_BASE_ADDR_MASK;
522                 mmu_page_remove_parent_pte(page_header(ent), &pt[i]);
523         }
524 }
525
526 static void kvm_mmu_put_page(struct kvm_vcpu *vcpu,
527                              struct kvm_mmu_page *page,
528                              u64 *parent_pte)
529 {
530         mmu_page_remove_parent_pte(page, parent_pte);
531 }
532
533 static void kvm_mmu_zap_page(struct kvm_vcpu *vcpu,
534                              struct kvm_mmu_page *page)
535 {
536         u64 *parent_pte;
537
538         while (page->multimapped || page->parent_pte) {
539                 if (!page->multimapped)
540                         parent_pte = page->parent_pte;
541                 else {
542                         struct kvm_pte_chain *chain;
543
544                         chain = container_of(page->parent_ptes.first,
545                                              struct kvm_pte_chain, link);
546                         parent_pte = chain->parent_ptes[0];
547                 }
548                 BUG_ON(!parent_pte);
549                 kvm_mmu_put_page(vcpu, page, parent_pte);
550                 *parent_pte = 0;
551         }
552         kvm_mmu_page_unlink_children(vcpu, page);
553         hlist_del(&page->hash_link);
554         kvm_mmu_free_page(vcpu, page->page_hpa);
555 }
556
557 static int kvm_mmu_unprotect_page(struct kvm_vcpu *vcpu, gfn_t gfn)
558 {
559         unsigned index;
560         struct hlist_head *bucket;
561         struct kvm_mmu_page *page;
562         struct hlist_node *node, *n;
563         int r;
564
565         pgprintk("%s: looking for gfn %lx\n", __FUNCTION__, gfn);
566         r = 0;
567         index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
568         bucket = &vcpu->kvm->mmu_page_hash[index];
569         hlist_for_each_entry_safe(page, node, n, bucket, hash_link)
570                 if (page->gfn == gfn && !page->role.metaphysical) {
571                         pgprintk("%s: gfn %lx role %x\n", __FUNCTION__, gfn,
572                                  page->role.word);
573                         kvm_mmu_zap_page(vcpu, page);
574                         r = 1;
575                 }
576         return r;
577 }
578
579 static void page_header_update_slot(struct kvm *kvm, void *pte, gpa_t gpa)
580 {
581         int slot = memslot_id(kvm, gfn_to_memslot(kvm, gpa >> PAGE_SHIFT));
582         struct kvm_mmu_page *page_head = page_header(__pa(pte));
583
584         __set_bit(slot, &page_head->slot_bitmap);
585 }
586
587 hpa_t safe_gpa_to_hpa(struct kvm_vcpu *vcpu, gpa_t gpa)
588 {
589         hpa_t hpa = gpa_to_hpa(vcpu, gpa);
590
591         return is_error_hpa(hpa) ? bad_page_address | (gpa & ~PAGE_MASK): hpa;
592 }
593
594 hpa_t gpa_to_hpa(struct kvm_vcpu *vcpu, gpa_t gpa)
595 {
596         struct kvm_memory_slot *slot;
597         struct page *page;
598
599         ASSERT((gpa & HPA_ERR_MASK) == 0);
600         slot = gfn_to_memslot(vcpu->kvm, gpa >> PAGE_SHIFT);
601         if (!slot)
602                 return gpa | HPA_ERR_MASK;
603         page = gfn_to_page(slot, gpa >> PAGE_SHIFT);
604         return ((hpa_t)page_to_pfn(page) << PAGE_SHIFT)
605                 | (gpa & (PAGE_SIZE-1));
606 }
607
608 hpa_t gva_to_hpa(struct kvm_vcpu *vcpu, gva_t gva)
609 {
610         gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, gva);
611
612         if (gpa == UNMAPPED_GVA)
613                 return UNMAPPED_GVA;
614         return gpa_to_hpa(vcpu, gpa);
615 }
616
617 static void nonpaging_new_cr3(struct kvm_vcpu *vcpu)
618 {
619 }
620
621 static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, hpa_t p)
622 {
623         int level = PT32E_ROOT_LEVEL;
624         hpa_t table_addr = vcpu->mmu.root_hpa;
625
626         for (; ; level--) {
627                 u32 index = PT64_INDEX(v, level);
628                 u64 *table;
629                 u64 pte;
630
631                 ASSERT(VALID_PAGE(table_addr));
632                 table = __va(table_addr);
633
634                 if (level == 1) {
635                         pte = table[index];
636                         if (is_present_pte(pte) && is_writeble_pte(pte))
637                                 return 0;
638                         mark_page_dirty(vcpu->kvm, v >> PAGE_SHIFT);
639                         page_header_update_slot(vcpu->kvm, table, v);
640                         table[index] = p | PT_PRESENT_MASK | PT_WRITABLE_MASK |
641                                                                 PT_USER_MASK;
642                         rmap_add(vcpu->kvm, &table[index]);
643                         return 0;
644                 }
645
646                 if (table[index] == 0) {
647                         struct kvm_mmu_page *new_table;
648                         gfn_t pseudo_gfn;
649
650                         pseudo_gfn = (v & PT64_DIR_BASE_ADDR_MASK)
651                                 >> PAGE_SHIFT;
652                         new_table = kvm_mmu_get_page(vcpu, pseudo_gfn,
653                                                      v, level - 1,
654                                                      1, &table[index]);
655                         if (!new_table) {
656                                 pgprintk("nonpaging_map: ENOMEM\n");
657                                 return -ENOMEM;
658                         }
659
660                         table[index] = new_table->page_hpa | PT_PRESENT_MASK
661                                 | PT_WRITABLE_MASK | PT_USER_MASK;
662                 }
663                 table_addr = table[index] & PT64_BASE_ADDR_MASK;
664         }
665 }
666
667 static void mmu_free_roots(struct kvm_vcpu *vcpu)
668 {
669         int i;
670
671 #ifdef CONFIG_X86_64
672         if (vcpu->mmu.shadow_root_level == PT64_ROOT_LEVEL) {
673                 hpa_t root = vcpu->mmu.root_hpa;
674
675                 ASSERT(VALID_PAGE(root));
676                 vcpu->mmu.root_hpa = INVALID_PAGE;
677                 return;
678         }
679 #endif
680         for (i = 0; i < 4; ++i) {
681                 hpa_t root = vcpu->mmu.pae_root[i];
682
683                 ASSERT(VALID_PAGE(root));
684                 root &= PT64_BASE_ADDR_MASK;
685                 vcpu->mmu.pae_root[i] = INVALID_PAGE;
686         }
687         vcpu->mmu.root_hpa = INVALID_PAGE;
688 }
689
690 static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
691 {
692         int i;
693         gfn_t root_gfn;
694         root_gfn = vcpu->cr3 >> PAGE_SHIFT;
695
696 #ifdef CONFIG_X86_64
697         if (vcpu->mmu.shadow_root_level == PT64_ROOT_LEVEL) {
698                 hpa_t root = vcpu->mmu.root_hpa;
699
700                 ASSERT(!VALID_PAGE(root));
701                 root = kvm_mmu_get_page(vcpu, root_gfn, 0,
702                                         PT64_ROOT_LEVEL, 0, NULL)->page_hpa;
703                 vcpu->mmu.root_hpa = root;
704                 return;
705         }
706 #endif
707         for (i = 0; i < 4; ++i) {
708                 hpa_t root = vcpu->mmu.pae_root[i];
709
710                 ASSERT(!VALID_PAGE(root));
711                 if (vcpu->mmu.root_level == PT32E_ROOT_LEVEL)
712                         root_gfn = vcpu->pdptrs[i] >> PAGE_SHIFT;
713                 else if (vcpu->mmu.root_level == 0)
714                         root_gfn = 0;
715                 root = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
716                                         PT32_ROOT_LEVEL, !is_paging(vcpu),
717                                         NULL)->page_hpa;
718                 vcpu->mmu.pae_root[i] = root | PT_PRESENT_MASK;
719         }
720         vcpu->mmu.root_hpa = __pa(vcpu->mmu.pae_root);
721 }
722
723 static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gva_t vaddr)
724 {
725         return vaddr;
726 }
727
728 static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
729                                u32 error_code)
730 {
731         gpa_t addr = gva;
732         hpa_t paddr;
733
734         ASSERT(vcpu);
735         ASSERT(VALID_PAGE(vcpu->mmu.root_hpa));
736
737
738         paddr = gpa_to_hpa(vcpu , addr & PT64_BASE_ADDR_MASK);
739
740         if (is_error_hpa(paddr))
741                 return 1;
742
743         return nonpaging_map(vcpu, addr & PAGE_MASK, paddr);
744 }
745
746 static void nonpaging_free(struct kvm_vcpu *vcpu)
747 {
748         mmu_free_roots(vcpu);
749 }
750
751 static int nonpaging_init_context(struct kvm_vcpu *vcpu)
752 {
753         struct kvm_mmu *context = &vcpu->mmu;
754
755         context->new_cr3 = nonpaging_new_cr3;
756         context->page_fault = nonpaging_page_fault;
757         context->gva_to_gpa = nonpaging_gva_to_gpa;
758         context->free = nonpaging_free;
759         context->root_level = 0;
760         context->shadow_root_level = PT32E_ROOT_LEVEL;
761         mmu_alloc_roots(vcpu);
762         ASSERT(VALID_PAGE(context->root_hpa));
763         kvm_arch_ops->set_cr3(vcpu, context->root_hpa);
764         return 0;
765 }
766
767 static void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu)
768 {
769         ++kvm_stat.tlb_flush;
770         kvm_arch_ops->tlb_flush(vcpu);
771 }
772
773 static void paging_new_cr3(struct kvm_vcpu *vcpu)
774 {
775         pgprintk("%s: cr3 %lx\n", __FUNCTION__, vcpu->cr3);
776         mmu_free_roots(vcpu);
777         mmu_alloc_roots(vcpu);
778         kvm_mmu_flush_tlb(vcpu);
779         kvm_arch_ops->set_cr3(vcpu, vcpu->mmu.root_hpa);
780 }
781
782 static void mark_pagetable_nonglobal(void *shadow_pte)
783 {
784         page_header(__pa(shadow_pte))->global = 0;
785 }
786
787 static inline void set_pte_common(struct kvm_vcpu *vcpu,
788                              u64 *shadow_pte,
789                              gpa_t gaddr,
790                              int dirty,
791                              u64 access_bits,
792                              gfn_t gfn)
793 {
794         hpa_t paddr;
795
796         *shadow_pte |= access_bits << PT_SHADOW_BITS_OFFSET;
797         if (!dirty)
798                 access_bits &= ~PT_WRITABLE_MASK;
799
800         paddr = gpa_to_hpa(vcpu, gaddr & PT64_BASE_ADDR_MASK);
801
802         *shadow_pte |= access_bits;
803
804         if (!(*shadow_pte & PT_GLOBAL_MASK))
805                 mark_pagetable_nonglobal(shadow_pte);
806
807         if (is_error_hpa(paddr)) {
808                 *shadow_pte |= gaddr;
809                 *shadow_pte |= PT_SHADOW_IO_MARK;
810                 *shadow_pte &= ~PT_PRESENT_MASK;
811                 return;
812         }
813
814         *shadow_pte |= paddr;
815
816         if (access_bits & PT_WRITABLE_MASK) {
817                 struct kvm_mmu_page *shadow;
818
819                 shadow = kvm_mmu_lookup_page(vcpu, gfn);
820                 if (shadow) {
821                         pgprintk("%s: found shadow page for %lx, marking ro\n",
822                                  __FUNCTION__, gfn);
823                         access_bits &= ~PT_WRITABLE_MASK;
824                         *shadow_pte &= ~PT_WRITABLE_MASK;
825                 }
826         }
827
828         if (access_bits & PT_WRITABLE_MASK)
829                 mark_page_dirty(vcpu->kvm, gaddr >> PAGE_SHIFT);
830
831         page_header_update_slot(vcpu->kvm, shadow_pte, gaddr);
832         rmap_add(vcpu->kvm, shadow_pte);
833 }
834
835 static void inject_page_fault(struct kvm_vcpu *vcpu,
836                               u64 addr,
837                               u32 err_code)
838 {
839         kvm_arch_ops->inject_page_fault(vcpu, addr, err_code);
840 }
841
842 static inline int fix_read_pf(u64 *shadow_ent)
843 {
844         if ((*shadow_ent & PT_SHADOW_USER_MASK) &&
845             !(*shadow_ent & PT_USER_MASK)) {
846                 /*
847                  * If supervisor write protect is disabled, we shadow kernel
848                  * pages as user pages so we can trap the write access.
849                  */
850                 *shadow_ent |= PT_USER_MASK;
851                 *shadow_ent &= ~PT_WRITABLE_MASK;
852
853                 return 1;
854
855         }
856         return 0;
857 }
858
859 static int may_access(u64 pte, int write, int user)
860 {
861
862         if (user && !(pte & PT_USER_MASK))
863                 return 0;
864         if (write && !(pte & PT_WRITABLE_MASK))
865                 return 0;
866         return 1;
867 }
868
869 static void paging_free(struct kvm_vcpu *vcpu)
870 {
871         nonpaging_free(vcpu);
872 }
873
874 #define PTTYPE 64
875 #include "paging_tmpl.h"
876 #undef PTTYPE
877
878 #define PTTYPE 32
879 #include "paging_tmpl.h"
880 #undef PTTYPE
881
882 static int paging64_init_context_common(struct kvm_vcpu *vcpu, int level)
883 {
884         struct kvm_mmu *context = &vcpu->mmu;
885
886         ASSERT(is_pae(vcpu));
887         context->new_cr3 = paging_new_cr3;
888         context->page_fault = paging64_page_fault;
889         context->gva_to_gpa = paging64_gva_to_gpa;
890         context->free = paging_free;
891         context->root_level = level;
892         context->shadow_root_level = level;
893         mmu_alloc_roots(vcpu);
894         ASSERT(VALID_PAGE(context->root_hpa));
895         kvm_arch_ops->set_cr3(vcpu, context->root_hpa |
896                     (vcpu->cr3 & (CR3_PCD_MASK | CR3_WPT_MASK)));
897         return 0;
898 }
899
900 static int paging64_init_context(struct kvm_vcpu *vcpu)
901 {
902         return paging64_init_context_common(vcpu, PT64_ROOT_LEVEL);
903 }
904
905 static int paging32_init_context(struct kvm_vcpu *vcpu)
906 {
907         struct kvm_mmu *context = &vcpu->mmu;
908
909         context->new_cr3 = paging_new_cr3;
910         context->page_fault = paging32_page_fault;
911         context->gva_to_gpa = paging32_gva_to_gpa;
912         context->free = paging_free;
913         context->root_level = PT32_ROOT_LEVEL;
914         context->shadow_root_level = PT32E_ROOT_LEVEL;
915         mmu_alloc_roots(vcpu);
916         ASSERT(VALID_PAGE(context->root_hpa));
917         kvm_arch_ops->set_cr3(vcpu, context->root_hpa |
918                     (vcpu->cr3 & (CR3_PCD_MASK | CR3_WPT_MASK)));
919         return 0;
920 }
921
922 static int paging32E_init_context(struct kvm_vcpu *vcpu)
923 {
924         return paging64_init_context_common(vcpu, PT32E_ROOT_LEVEL);
925 }
926
927 static int init_kvm_mmu(struct kvm_vcpu *vcpu)
928 {
929         ASSERT(vcpu);
930         ASSERT(!VALID_PAGE(vcpu->mmu.root_hpa));
931
932         if (!is_paging(vcpu))
933                 return nonpaging_init_context(vcpu);
934         else if (is_long_mode(vcpu))
935                 return paging64_init_context(vcpu);
936         else if (is_pae(vcpu))
937                 return paging32E_init_context(vcpu);
938         else
939                 return paging32_init_context(vcpu);
940 }
941
942 static void destroy_kvm_mmu(struct kvm_vcpu *vcpu)
943 {
944         ASSERT(vcpu);
945         if (VALID_PAGE(vcpu->mmu.root_hpa)) {
946                 vcpu->mmu.free(vcpu);
947                 vcpu->mmu.root_hpa = INVALID_PAGE;
948         }
949 }
950
951 int kvm_mmu_reset_context(struct kvm_vcpu *vcpu)
952 {
953         destroy_kvm_mmu(vcpu);
954         return init_kvm_mmu(vcpu);
955 }
956
957 void kvm_mmu_pre_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes)
958 {
959         gfn_t gfn = gpa >> PAGE_SHIFT;
960         struct kvm_mmu_page *page;
961         struct kvm_mmu_page *child;
962         struct hlist_node *node, *n;
963         struct hlist_head *bucket;
964         unsigned index;
965         u64 *spte;
966         u64 pte;
967         unsigned offset = offset_in_page(gpa);
968         unsigned pte_size;
969         unsigned page_offset;
970         unsigned misaligned;
971         int level;
972         int flooded = 0;
973
974         pgprintk("%s: gpa %llx bytes %d\n", __FUNCTION__, gpa, bytes);
975         if (gfn == vcpu->last_pt_write_gfn) {
976                 ++vcpu->last_pt_write_count;
977                 if (vcpu->last_pt_write_count >= 3)
978                         flooded = 1;
979         } else {
980                 vcpu->last_pt_write_gfn = gfn;
981                 vcpu->last_pt_write_count = 1;
982         }
983         index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
984         bucket = &vcpu->kvm->mmu_page_hash[index];
985         hlist_for_each_entry_safe(page, node, n, bucket, hash_link) {
986                 if (page->gfn != gfn || page->role.metaphysical)
987                         continue;
988                 pte_size = page->role.glevels == PT32_ROOT_LEVEL ? 4 : 8;
989                 misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1);
990                 if (misaligned || flooded) {
991                         /*
992                          * Misaligned accesses are too much trouble to fix
993                          * up; also, they usually indicate a page is not used
994                          * as a page table.
995                          *
996                          * If we're seeing too many writes to a page,
997                          * it may no longer be a page table, or we may be
998                          * forking, in which case it is better to unmap the
999                          * page.
1000                          */
1001                         pgprintk("misaligned: gpa %llx bytes %d role %x\n",
1002                                  gpa, bytes, page->role.word);
1003                         kvm_mmu_zap_page(vcpu, page);
1004                         continue;
1005                 }
1006                 page_offset = offset;
1007                 level = page->role.level;
1008                 if (page->role.glevels == PT32_ROOT_LEVEL) {
1009                         page_offset <<= 1;          /* 32->64 */
1010                         page_offset &= ~PAGE_MASK;
1011                 }
1012                 spte = __va(page->page_hpa);
1013                 spte += page_offset / sizeof(*spte);
1014                 pte = *spte;
1015                 if (is_present_pte(pte)) {
1016                         if (level == PT_PAGE_TABLE_LEVEL)
1017                                 rmap_remove(vcpu->kvm, spte);
1018                         else {
1019                                 child = page_header(pte & PT64_BASE_ADDR_MASK);
1020                                 mmu_page_remove_parent_pte(child, spte);
1021                         }
1022                 }
1023                 *spte = 0;
1024         }
1025 }
1026
1027 void kvm_mmu_post_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes)
1028 {
1029 }
1030
1031 int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
1032 {
1033         gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, gva);
1034
1035         return kvm_mmu_unprotect_page(vcpu, gpa >> PAGE_SHIFT);
1036 }
1037
1038 void kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
1039 {
1040         while (vcpu->kvm->n_free_mmu_pages < KVM_REFILL_PAGES) {
1041                 struct kvm_mmu_page *page;
1042
1043                 page = container_of(vcpu->kvm->active_mmu_pages.prev,
1044                                     struct kvm_mmu_page, link);
1045                 kvm_mmu_zap_page(vcpu, page);
1046         }
1047 }
1048 EXPORT_SYMBOL_GPL(kvm_mmu_free_some_pages);
1049
1050 static void free_mmu_pages(struct kvm_vcpu *vcpu)
1051 {
1052         while (!list_empty(&vcpu->free_pages)) {
1053                 struct kvm_mmu_page *page;
1054
1055                 page = list_entry(vcpu->free_pages.next,
1056                                   struct kvm_mmu_page, link);
1057                 list_del(&page->link);
1058                 __free_page(pfn_to_page(page->page_hpa >> PAGE_SHIFT));
1059                 page->page_hpa = INVALID_PAGE;
1060         }
1061         free_page((unsigned long)vcpu->mmu.pae_root);
1062 }
1063
1064 static int alloc_mmu_pages(struct kvm_vcpu *vcpu)
1065 {
1066         struct page *page;
1067         int i;
1068
1069         ASSERT(vcpu);
1070
1071         for (i = 0; i < KVM_NUM_MMU_PAGES; i++) {
1072                 struct kvm_mmu_page *page_header = &vcpu->page_header_buf[i];
1073
1074                 INIT_LIST_HEAD(&page_header->link);
1075                 if ((page = alloc_page(GFP_KERNEL)) == NULL)
1076                         goto error_1;
1077                 page->private = (unsigned long)page_header;
1078                 page_header->page_hpa = (hpa_t)page_to_pfn(page) << PAGE_SHIFT;
1079                 memset(__va(page_header->page_hpa), 0, PAGE_SIZE);
1080                 list_add(&page_header->link, &vcpu->free_pages);
1081                 ++vcpu->kvm->n_free_mmu_pages;
1082         }
1083
1084         /*
1085          * When emulating 32-bit mode, cr3 is only 32 bits even on x86_64.
1086          * Therefore we need to allocate shadow page tables in the first
1087          * 4GB of memory, which happens to fit the DMA32 zone.
1088          */
1089         page = alloc_page(GFP_KERNEL | __GFP_DMA32);
1090         if (!page)
1091                 goto error_1;
1092         vcpu->mmu.pae_root = page_address(page);
1093         for (i = 0; i < 4; ++i)
1094                 vcpu->mmu.pae_root[i] = INVALID_PAGE;
1095
1096         return 0;
1097
1098 error_1:
1099         free_mmu_pages(vcpu);
1100         return -ENOMEM;
1101 }
1102
1103 int kvm_mmu_create(struct kvm_vcpu *vcpu)
1104 {
1105         ASSERT(vcpu);
1106         ASSERT(!VALID_PAGE(vcpu->mmu.root_hpa));
1107         ASSERT(list_empty(&vcpu->free_pages));
1108
1109         return alloc_mmu_pages(vcpu);
1110 }
1111
1112 int kvm_mmu_setup(struct kvm_vcpu *vcpu)
1113 {
1114         ASSERT(vcpu);
1115         ASSERT(!VALID_PAGE(vcpu->mmu.root_hpa));
1116         ASSERT(!list_empty(&vcpu->free_pages));
1117
1118         return init_kvm_mmu(vcpu);
1119 }
1120
1121 void kvm_mmu_destroy(struct kvm_vcpu *vcpu)
1122 {
1123         ASSERT(vcpu);
1124
1125         destroy_kvm_mmu(vcpu);
1126         free_mmu_pages(vcpu);
1127 }
1128
1129 void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
1130 {
1131         struct kvm_mmu_page *page;
1132
1133         list_for_each_entry(page, &kvm->active_mmu_pages, link) {
1134                 int i;
1135                 u64 *pt;
1136
1137                 if (!test_bit(slot, &page->slot_bitmap))
1138                         continue;
1139
1140                 pt = __va(page->page_hpa);
1141                 for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
1142                         /* avoid RMW */
1143                         if (pt[i] & PT_WRITABLE_MASK) {
1144                                 rmap_remove(kvm, &pt[i]);
1145                                 pt[i] &= ~PT_WRITABLE_MASK;
1146                         }
1147         }
1148 }