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af585b92 GN |
1 | /* |
2 | * kvm asynchronous fault support | |
3 | * | |
4 | * Copyright 2010 Red Hat, Inc. | |
5 | * | |
6 | * Author: | |
7 | * Gleb Natapov <gleb@redhat.com> | |
8 | * | |
9 | * This file is free software; you can redistribute it and/or modify | |
10 | * it under the terms of version 2 of the GNU General Public License | |
11 | * as published by the Free Software Foundation. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program; if not, write to the Free Software Foundation, | |
20 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. | |
21 | */ | |
22 | ||
23 | #include <linux/kvm_host.h> | |
24 | #include <linux/slab.h> | |
25 | #include <linux/module.h> | |
26 | #include <linux/mmu_context.h> | |
27 | ||
28 | #include "async_pf.h" | |
29 | #include <trace/events/kvm.h> | |
30 | ||
31 | static struct kmem_cache *async_pf_cache; | |
32 | ||
33 | int kvm_async_pf_init(void) | |
34 | { | |
35 | async_pf_cache = KMEM_CACHE(kvm_async_pf, 0); | |
36 | ||
37 | if (!async_pf_cache) | |
38 | return -ENOMEM; | |
39 | ||
40 | return 0; | |
41 | } | |
42 | ||
43 | void kvm_async_pf_deinit(void) | |
44 | { | |
45 | if (async_pf_cache) | |
46 | kmem_cache_destroy(async_pf_cache); | |
47 | async_pf_cache = NULL; | |
48 | } | |
49 | ||
50 | void kvm_async_pf_vcpu_init(struct kvm_vcpu *vcpu) | |
51 | { | |
52 | INIT_LIST_HEAD(&vcpu->async_pf.done); | |
53 | INIT_LIST_HEAD(&vcpu->async_pf.queue); | |
54 | spin_lock_init(&vcpu->async_pf.lock); | |
55 | } | |
56 | ||
57 | static void async_pf_execute(struct work_struct *work) | |
58 | { | |
59 | struct page *page = NULL; | |
60 | struct kvm_async_pf *apf = | |
61 | container_of(work, struct kvm_async_pf, work); | |
62 | struct mm_struct *mm = apf->mm; | |
63 | struct kvm_vcpu *vcpu = apf->vcpu; | |
64 | unsigned long addr = apf->addr; | |
65 | gva_t gva = apf->gva; | |
66 | ||
67 | might_sleep(); | |
68 | ||
69 | use_mm(mm); | |
70 | down_read(&mm->mmap_sem); | |
71 | get_user_pages(current, mm, addr, 1, 1, 0, &page, NULL); | |
72 | up_read(&mm->mmap_sem); | |
73 | unuse_mm(mm); | |
74 | ||
75 | spin_lock(&vcpu->async_pf.lock); | |
76 | list_add_tail(&apf->link, &vcpu->async_pf.done); | |
77 | apf->page = page; | |
af585b92 GN |
78 | spin_unlock(&vcpu->async_pf.lock); |
79 | ||
80 | /* | |
81 | * apf may be freed by kvm_check_async_pf_completion() after | |
82 | * this point | |
83 | */ | |
84 | ||
85 | trace_kvm_async_pf_completed(addr, page, gva); | |
86 | ||
87 | if (waitqueue_active(&vcpu->wq)) | |
88 | wake_up_interruptible(&vcpu->wq); | |
89 | ||
90 | mmdrop(mm); | |
91 | kvm_put_kvm(vcpu->kvm); | |
92 | } | |
93 | ||
94 | void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu) | |
95 | { | |
96 | /* cancel outstanding work queue item */ | |
97 | while (!list_empty(&vcpu->async_pf.queue)) { | |
98 | struct kvm_async_pf *work = | |
99 | list_entry(vcpu->async_pf.queue.next, | |
100 | typeof(*work), queue); | |
af585b92 | 101 | list_del(&work->queue); |
98fda169 | 102 | if (cancel_work_sync(&work->work)) { |
28b441e2 RK |
103 | mmdrop(work->mm); |
104 | kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */ | |
af585b92 | 105 | kmem_cache_free(async_pf_cache, work); |
28b441e2 | 106 | } |
af585b92 GN |
107 | } |
108 | ||
109 | spin_lock(&vcpu->async_pf.lock); | |
110 | while (!list_empty(&vcpu->async_pf.done)) { | |
111 | struct kvm_async_pf *work = | |
112 | list_entry(vcpu->async_pf.done.next, | |
113 | typeof(*work), link); | |
114 | list_del(&work->link); | |
32cad84f | 115 | if (!is_error_page(work->page)) |
2b4b5af8 | 116 | kvm_release_page_clean(work->page); |
af585b92 GN |
117 | kmem_cache_free(async_pf_cache, work); |
118 | } | |
119 | spin_unlock(&vcpu->async_pf.lock); | |
120 | ||
121 | vcpu->async_pf.queued = 0; | |
122 | } | |
123 | ||
124 | void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu) | |
125 | { | |
126 | struct kvm_async_pf *work; | |
127 | ||
15096ffc XG |
128 | while (!list_empty_careful(&vcpu->async_pf.done) && |
129 | kvm_arch_can_inject_async_page_present(vcpu)) { | |
130 | spin_lock(&vcpu->async_pf.lock); | |
131 | work = list_first_entry(&vcpu->async_pf.done, typeof(*work), | |
132 | link); | |
133 | list_del(&work->link); | |
134 | spin_unlock(&vcpu->async_pf.lock); | |
af585b92 | 135 | |
15096ffc XG |
136 | if (work->page) |
137 | kvm_arch_async_page_ready(vcpu, work); | |
138 | kvm_arch_async_page_present(vcpu, work); | |
af585b92 | 139 | |
15096ffc XG |
140 | list_del(&work->queue); |
141 | vcpu->async_pf.queued--; | |
32cad84f | 142 | if (!is_error_page(work->page)) |
2b4b5af8 | 143 | kvm_release_page_clean(work->page); |
15096ffc XG |
144 | kmem_cache_free(async_pf_cache, work); |
145 | } | |
af585b92 GN |
146 | } |
147 | ||
148 | int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn, | |
149 | struct kvm_arch_async_pf *arch) | |
150 | { | |
151 | struct kvm_async_pf *work; | |
152 | ||
153 | if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU) | |
154 | return 0; | |
155 | ||
156 | /* setup delayed work */ | |
157 | ||
158 | /* | |
159 | * do alloc nowait since if we are going to sleep anyway we | |
160 | * may as well sleep faulting in page | |
161 | */ | |
162 | work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT); | |
163 | if (!work) | |
164 | return 0; | |
165 | ||
166 | work->page = NULL; | |
af585b92 GN |
167 | work->vcpu = vcpu; |
168 | work->gva = gva; | |
169 | work->addr = gfn_to_hva(vcpu->kvm, gfn); | |
170 | work->arch = *arch; | |
171 | work->mm = current->mm; | |
172 | atomic_inc(&work->mm->mm_count); | |
173 | kvm_get_kvm(work->vcpu->kvm); | |
174 | ||
175 | /* this can't really happen otherwise gfn_to_pfn_async | |
176 | would succeed */ | |
177 | if (unlikely(kvm_is_error_hva(work->addr))) | |
178 | goto retry_sync; | |
179 | ||
180 | INIT_WORK(&work->work, async_pf_execute); | |
181 | if (!schedule_work(&work->work)) | |
182 | goto retry_sync; | |
183 | ||
184 | list_add_tail(&work->queue, &vcpu->async_pf.queue); | |
185 | vcpu->async_pf.queued++; | |
186 | kvm_arch_async_page_not_present(vcpu, work); | |
187 | return 1; | |
188 | retry_sync: | |
189 | kvm_put_kvm(work->vcpu->kvm); | |
190 | mmdrop(work->mm); | |
191 | kmem_cache_free(async_pf_cache, work); | |
192 | return 0; | |
193 | } | |
344d9588 GN |
194 | |
195 | int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu) | |
196 | { | |
197 | struct kvm_async_pf *work; | |
198 | ||
64f638c7 | 199 | if (!list_empty_careful(&vcpu->async_pf.done)) |
344d9588 GN |
200 | return 0; |
201 | ||
202 | work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC); | |
203 | if (!work) | |
204 | return -ENOMEM; | |
205 | ||
6cede2e6 | 206 | work->page = KVM_ERR_PTR_BAD_PAGE; |
344d9588 GN |
207 | INIT_LIST_HEAD(&work->queue); /* for list_del to work */ |
208 | ||
64f638c7 | 209 | spin_lock(&vcpu->async_pf.lock); |
344d9588 | 210 | list_add_tail(&work->link, &vcpu->async_pf.done); |
64f638c7 XG |
211 | spin_unlock(&vcpu->async_pf.lock); |
212 | ||
344d9588 GN |
213 | vcpu->async_pf.queued++; |
214 | return 0; | |
215 | } |