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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
31static 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}
38static 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
46static struct kmem_cache *async_pf_cache;
47
48int 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
58void kvm_async_pf_deinit(void)
59{
60 kmem_cache_destroy(async_pf_cache);
61 async_pf_cache = NULL;
62}
63
64void kvm_async_pf_vcpu_init(struct kvm_vcpu *vcpu)
65{
66 INIT_LIST_HEAD(&vcpu->async_pf.done);
67 INIT_LIST_HEAD(&vcpu->async_pf.queue);
68 spin_lock_init(&vcpu->async_pf.lock);
69}
70
71static void async_pf_execute(struct work_struct *work)
72{
73 struct kvm_async_pf *apf =
74 container_of(work, struct kvm_async_pf, work);
75 struct mm_struct *mm = apf->mm;
76 struct kvm_vcpu *vcpu = apf->vcpu;
77 unsigned long addr = apf->addr;
78 gva_t gva = apf->gva;
79
80 might_sleep();
81
82 /*
83 * This work is run asynchromously to the task which owns
84 * mm and might be done in another context, so we must
85 * use FOLL_REMOTE.
86 */
87 __get_user_pages_unlocked(NULL, mm, addr, 1, 1, 0, NULL, FOLL_REMOTE);
88
89 kvm_async_page_present_sync(vcpu, apf);
90
91 spin_lock(&vcpu->async_pf.lock);
92 list_add_tail(&apf->link, &vcpu->async_pf.done);
93 spin_unlock(&vcpu->async_pf.lock);
94
95 /*
96 * apf may be freed by kvm_check_async_pf_completion() after
97 * this point
98 */
99
100 trace_kvm_async_pf_completed(addr, gva);
101
102 /*
103 * This memory barrier pairs with prepare_to_wait's set_current_state()
104 */
105 smp_mb();
106 if (swait_active(&vcpu->wq))
107 swake_up(&vcpu->wq);
108
109 mmput(mm);
110 kvm_put_kvm(vcpu->kvm);
111}
112
113void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
114{
115 /* cancel outstanding work queue item */
116 while (!list_empty(&vcpu->async_pf.queue)) {
117 struct kvm_async_pf *work =
118 list_first_entry(&vcpu->async_pf.queue,
119 typeof(*work), queue);
120 list_del(&work->queue);
121
122#ifdef CONFIG_KVM_ASYNC_PF_SYNC
123 flush_work(&work->work);
124#else
125 if (cancel_work_sync(&work->work)) {
126 mmput(work->mm);
127 kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */
128 kmem_cache_free(async_pf_cache, work);
129 }
130#endif
131 }
132
133 spin_lock(&vcpu->async_pf.lock);
134 while (!list_empty(&vcpu->async_pf.done)) {
135 struct kvm_async_pf *work =
136 list_first_entry(&vcpu->async_pf.done,
137 typeof(*work), link);
138 list_del(&work->link);
139 kmem_cache_free(async_pf_cache, work);
140 }
141 spin_unlock(&vcpu->async_pf.lock);
142
143 vcpu->async_pf.queued = 0;
144}
145
146void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
147{
148 struct kvm_async_pf *work;
149
150 while (!list_empty_careful(&vcpu->async_pf.done) &&
151 kvm_arch_can_inject_async_page_present(vcpu)) {
152 spin_lock(&vcpu->async_pf.lock);
153 work = list_first_entry(&vcpu->async_pf.done, typeof(*work),
154 link);
155 list_del(&work->link);
156 spin_unlock(&vcpu->async_pf.lock);
157
158 kvm_arch_async_page_ready(vcpu, work);
159 kvm_async_page_present_async(vcpu, work);
160
161 list_del(&work->queue);
162 vcpu->async_pf.queued--;
163 kmem_cache_free(async_pf_cache, work);
164 }
165}
166
167int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva,
168 struct kvm_arch_async_pf *arch)
169{
170 struct kvm_async_pf *work;
171
172 if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
173 return 0;
174
175 /* setup delayed work */
176
177 /*
178 * do alloc nowait since if we are going to sleep anyway we
179 * may as well sleep faulting in page
180 */
181 work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT | __GFP_NOWARN);
182 if (!work)
183 return 0;
184
185 work->wakeup_all = false;
186 work->vcpu = vcpu;
187 work->gva = gva;
188 work->addr = hva;
189 work->arch = *arch;
190 work->mm = current->mm;
191 atomic_inc(&work->mm->mm_users);
192 kvm_get_kvm(work->vcpu->kvm);
193
194 /* this can't really happen otherwise gfn_to_pfn_async
195 would succeed */
196 if (unlikely(kvm_is_error_hva(work->addr)))
197 goto retry_sync;
198
199 INIT_WORK(&work->work, async_pf_execute);
200 if (!schedule_work(&work->work))
201 goto retry_sync;
202
203 list_add_tail(&work->queue, &vcpu->async_pf.queue);
204 vcpu->async_pf.queued++;
205 kvm_arch_async_page_not_present(vcpu, work);
206 return 1;
207retry_sync:
208 kvm_put_kvm(work->vcpu->kvm);
209 mmput(work->mm);
210 kmem_cache_free(async_pf_cache, work);
211 return 0;
212}
213
214int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
215{
216 struct kvm_async_pf *work;
217
218 if (!list_empty_careful(&vcpu->async_pf.done))
219 return 0;
220
221 work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
222 if (!work)
223 return -ENOMEM;
224
225 work->wakeup_all = true;
226 INIT_LIST_HEAD(&work->queue); /* for list_del to work */
227
228 spin_lock(&vcpu->async_pf.lock);
229 list_add_tail(&work->link, &vcpu->async_pf.done);
230 spin_unlock(&vcpu->async_pf.lock);
231
232 vcpu->async_pf.queued++;
233 return 0;
234}
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
31static 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}
38static 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
46static struct kmem_cache *async_pf_cache;
47
48int 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
58void kvm_async_pf_deinit(void)
59{
60 kmem_cache_destroy(async_pf_cache);
61 async_pf_cache = NULL;
62}
63
64void kvm_async_pf_vcpu_init(struct kvm_vcpu *vcpu)
65{
66 INIT_LIST_HEAD(&vcpu->async_pf.done);
67 INIT_LIST_HEAD(&vcpu->async_pf.queue);
68 spin_lock_init(&vcpu->async_pf.lock);
69}
70
71static void async_pf_execute(struct work_struct *work)
72{
73 struct kvm_async_pf *apf =
74 container_of(work, struct kvm_async_pf, work);
75 struct mm_struct *mm = apf->mm;
76 struct kvm_vcpu *vcpu = apf->vcpu;
77 unsigned long addr = apf->addr;
78 gva_t gva = apf->gva;
79 int locked = 1;
80
81 might_sleep();
82
83 /*
84 * This work is run asynchromously to the task which owns
85 * mm and might be done in another context, so we must
86 * access remotely.
87 */
88 down_read(&mm->mmap_sem);
89 get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE, NULL, NULL,
90 &locked);
91 if (locked)
92 up_read(&mm->mmap_sem);
93
94 kvm_async_page_present_sync(vcpu, apf);
95
96 spin_lock(&vcpu->async_pf.lock);
97 list_add_tail(&apf->link, &vcpu->async_pf.done);
98 apf->vcpu = NULL;
99 spin_unlock(&vcpu->async_pf.lock);
100
101 /*
102 * apf may be freed by kvm_check_async_pf_completion() after
103 * this point
104 */
105
106 trace_kvm_async_pf_completed(addr, gva);
107
108 /*
109 * This memory barrier pairs with prepare_to_wait's set_current_state()
110 */
111 smp_mb();
112 if (swait_active(&vcpu->wq))
113 swake_up(&vcpu->wq);
114
115 mmput(mm);
116 kvm_put_kvm(vcpu->kvm);
117}
118
119void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
120{
121 spin_lock(&vcpu->async_pf.lock);
122
123 /* cancel outstanding work queue item */
124 while (!list_empty(&vcpu->async_pf.queue)) {
125 struct kvm_async_pf *work =
126 list_first_entry(&vcpu->async_pf.queue,
127 typeof(*work), queue);
128 list_del(&work->queue);
129
130 /*
131 * We know it's present in vcpu->async_pf.done, do
132 * nothing here.
133 */
134 if (!work->vcpu)
135 continue;
136
137 spin_unlock(&vcpu->async_pf.lock);
138#ifdef CONFIG_KVM_ASYNC_PF_SYNC
139 flush_work(&work->work);
140#else
141 if (cancel_work_sync(&work->work)) {
142 mmput(work->mm);
143 kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */
144 kmem_cache_free(async_pf_cache, work);
145 }
146#endif
147 spin_lock(&vcpu->async_pf.lock);
148 }
149
150 while (!list_empty(&vcpu->async_pf.done)) {
151 struct kvm_async_pf *work =
152 list_first_entry(&vcpu->async_pf.done,
153 typeof(*work), link);
154 list_del(&work->link);
155 kmem_cache_free(async_pf_cache, work);
156 }
157 spin_unlock(&vcpu->async_pf.lock);
158
159 vcpu->async_pf.queued = 0;
160}
161
162void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
163{
164 struct kvm_async_pf *work;
165
166 while (!list_empty_careful(&vcpu->async_pf.done) &&
167 kvm_arch_can_inject_async_page_present(vcpu)) {
168 spin_lock(&vcpu->async_pf.lock);
169 work = list_first_entry(&vcpu->async_pf.done, typeof(*work),
170 link);
171 list_del(&work->link);
172 spin_unlock(&vcpu->async_pf.lock);
173
174 kvm_arch_async_page_ready(vcpu, work);
175 kvm_async_page_present_async(vcpu, work);
176
177 list_del(&work->queue);
178 vcpu->async_pf.queued--;
179 kmem_cache_free(async_pf_cache, work);
180 }
181}
182
183int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva,
184 struct kvm_arch_async_pf *arch)
185{
186 struct kvm_async_pf *work;
187
188 if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
189 return 0;
190
191 /* setup delayed work */
192
193 /*
194 * do alloc nowait since if we are going to sleep anyway we
195 * may as well sleep faulting in page
196 */
197 work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT | __GFP_NOWARN);
198 if (!work)
199 return 0;
200
201 work->wakeup_all = false;
202 work->vcpu = vcpu;
203 work->gva = gva;
204 work->addr = hva;
205 work->arch = *arch;
206 work->mm = current->mm;
207 atomic_inc(&work->mm->mm_users);
208 kvm_get_kvm(work->vcpu->kvm);
209
210 /* this can't really happen otherwise gfn_to_pfn_async
211 would succeed */
212 if (unlikely(kvm_is_error_hva(work->addr)))
213 goto retry_sync;
214
215 INIT_WORK(&work->work, async_pf_execute);
216 if (!schedule_work(&work->work))
217 goto retry_sync;
218
219 list_add_tail(&work->queue, &vcpu->async_pf.queue);
220 vcpu->async_pf.queued++;
221 kvm_arch_async_page_not_present(vcpu, work);
222 return 1;
223retry_sync:
224 kvm_put_kvm(work->vcpu->kvm);
225 mmput(work->mm);
226 kmem_cache_free(async_pf_cache, work);
227 return 0;
228}
229
230int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
231{
232 struct kvm_async_pf *work;
233
234 if (!list_empty_careful(&vcpu->async_pf.done))
235 return 0;
236
237 work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
238 if (!work)
239 return -ENOMEM;
240
241 work->wakeup_all = true;
242 INIT_LIST_HEAD(&work->queue); /* for list_del to work */
243
244 spin_lock(&vcpu->async_pf.lock);
245 list_add_tail(&work->link, &vcpu->async_pf.done);
246 spin_unlock(&vcpu->async_pf.lock);
247
248 vcpu->async_pf.queued++;
249 return 0;
250}