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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 inline void kvm_async_page_present_sync(struct kvm_vcpu *vcpu, |
32 | struct kvm_async_pf *work) |
33 | { |
34 | #ifdef CONFIG_KVM_ASYNC_PF_SYNC |
35 | kvm_arch_async_page_present(vcpu, work); |
36 | #endif |
37 | } |
38 | static inline void kvm_async_page_present_async(struct kvm_vcpu *vcpu, |
39 | struct kvm_async_pf *work) |
40 | { |
41 | #ifndef CONFIG_KVM_ASYNC_PF_SYNC |
42 | kvm_arch_async_page_present(vcpu, work); |
43 | #endif |
44 | } |
45 | |
46 | static struct kmem_cache *async_pf_cache; |
47 | |
48 | int kvm_async_pf_init(void) |
49 | { |
50 | async_pf_cache = KMEM_CACHE(kvm_async_pf, 0); |
51 | |
52 | if (!async_pf_cache) |
53 | return -ENOMEM; |
54 | |
55 | return 0; |
56 | } |
57 | |
58 | void kvm_async_pf_deinit(void) |
59 | { |
60 | if (async_pf_cache) |
61 | kmem_cache_destroy(async_pf_cache); |
62 | async_pf_cache = NULL; |
63 | } |
64 | |
65 | void kvm_async_pf_vcpu_init(struct kvm_vcpu *vcpu) |
66 | { |
67 | INIT_LIST_HEAD(&vcpu->async_pf.done); |
68 | INIT_LIST_HEAD(&vcpu->async_pf.queue); |
69 | spin_lock_init(&vcpu->async_pf.lock); |
70 | } |
71 | |
72 | static void async_pf_execute(struct work_struct *work) |
73 | { |
74 | struct kvm_async_pf *apf = |
75 | container_of(work, struct kvm_async_pf, work); |
76 | struct mm_struct *mm = apf->mm; |
77 | struct kvm_vcpu *vcpu = apf->vcpu; |
78 | unsigned long addr = apf->addr; |
79 | gva_t gva = apf->gva; |
80 | |
81 | might_sleep(); |
82 | |
83 | kvm_get_user_page_io(NULL, mm, addr, 1, NULL); |
84 | kvm_async_page_present_sync(vcpu, apf); |
85 | |
86 | spin_lock(&vcpu->async_pf.lock); |
87 | list_add_tail(&apf->link, &vcpu->async_pf.done); |
88 | spin_unlock(&vcpu->async_pf.lock); |
89 | |
90 | /* |
91 | * apf may be freed by kvm_check_async_pf_completion() after |
92 | * this point |
93 | */ |
94 | |
95 | trace_kvm_async_pf_completed(addr, gva); |
96 | |
97 | if (waitqueue_active(&vcpu->wq)) |
98 | wake_up_interruptible(&vcpu->wq); |
99 | |
100 | mmput(mm); |
101 | kvm_put_kvm(vcpu->kvm); |
102 | } |
103 | |
104 | void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu) |
105 | { |
106 | /* cancel outstanding work queue item */ |
107 | while (!list_empty(&vcpu->async_pf.queue)) { |
108 | struct kvm_async_pf *work = |
109 | list_entry(vcpu->async_pf.queue.next, |
110 | typeof(*work), queue); |
111 | list_del(&work->queue); |
112 | |
113 | #ifdef CONFIG_KVM_ASYNC_PF_SYNC |
114 | flush_work(&work->work); |
115 | #else |
116 | if (cancel_work_sync(&work->work)) { |
117 | mmput(work->mm); |
118 | kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */ |
119 | kmem_cache_free(async_pf_cache, work); |
120 | } |
121 | #endif |
122 | } |
123 | |
124 | spin_lock(&vcpu->async_pf.lock); |
125 | while (!list_empty(&vcpu->async_pf.done)) { |
126 | struct kvm_async_pf *work = |
127 | list_entry(vcpu->async_pf.done.next, |
128 | typeof(*work), link); |
129 | list_del(&work->link); |
130 | kmem_cache_free(async_pf_cache, work); |
131 | } |
132 | spin_unlock(&vcpu->async_pf.lock); |
133 | |
134 | vcpu->async_pf.queued = 0; |
135 | } |
136 | |
137 | void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu) |
138 | { |
139 | struct kvm_async_pf *work; |
140 | |
141 | while (!list_empty_careful(&vcpu->async_pf.done) && |
142 | kvm_arch_can_inject_async_page_present(vcpu)) { |
143 | spin_lock(&vcpu->async_pf.lock); |
144 | work = list_first_entry(&vcpu->async_pf.done, typeof(*work), |
145 | link); |
146 | list_del(&work->link); |
147 | spin_unlock(&vcpu->async_pf.lock); |
148 | |
149 | kvm_arch_async_page_ready(vcpu, work); |
150 | kvm_async_page_present_async(vcpu, work); |
151 | |
152 | list_del(&work->queue); |
153 | vcpu->async_pf.queued--; |
154 | kmem_cache_free(async_pf_cache, work); |
155 | } |
156 | } |
157 | |
158 | int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva, |
159 | struct kvm_arch_async_pf *arch) |
160 | { |
161 | struct kvm_async_pf *work; |
162 | |
163 | if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU) |
164 | return 0; |
165 | |
166 | /* setup delayed work */ |
167 | |
168 | /* |
169 | * do alloc nowait since if we are going to sleep anyway we |
170 | * may as well sleep faulting in page |
171 | */ |
172 | work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT); |
173 | if (!work) |
174 | return 0; |
175 | |
176 | work->wakeup_all = false; |
177 | work->vcpu = vcpu; |
178 | work->gva = gva; |
179 | work->addr = hva; |
180 | work->arch = *arch; |
181 | work->mm = current->mm; |
182 | atomic_inc(&work->mm->mm_users); |
183 | kvm_get_kvm(work->vcpu->kvm); |
184 | |
185 | /* this can't really happen otherwise gfn_to_pfn_async |
186 | would succeed */ |
187 | if (unlikely(kvm_is_error_hva(work->addr))) |
188 | goto retry_sync; |
189 | |
190 | INIT_WORK(&work->work, async_pf_execute); |
191 | if (!schedule_work(&work->work)) |
192 | goto retry_sync; |
193 | |
194 | list_add_tail(&work->queue, &vcpu->async_pf.queue); |
195 | vcpu->async_pf.queued++; |
196 | kvm_arch_async_page_not_present(vcpu, work); |
197 | return 1; |
198 | retry_sync: |
199 | kvm_put_kvm(work->vcpu->kvm); |
200 | mmput(work->mm); |
201 | kmem_cache_free(async_pf_cache, work); |
202 | return 0; |
203 | } |
204 | |
205 | int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu) |
206 | { |
207 | struct kvm_async_pf *work; |
208 | |
209 | if (!list_empty_careful(&vcpu->async_pf.done)) |
210 | return 0; |
211 | |
212 | work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC); |
213 | if (!work) |
214 | return -ENOMEM; |
215 | |
216 | work->wakeup_all = true; |
217 | INIT_LIST_HEAD(&work->queue); /* for list_del to work */ |
218 | |
219 | spin_lock(&vcpu->async_pf.lock); |
220 | list_add_tail(&work->link, &vcpu->async_pf.done); |
221 | spin_unlock(&vcpu->async_pf.lock); |
222 | |
223 | vcpu->async_pf.queued++; |
224 | return 0; |
225 | } |
226 |
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