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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 if (async_pf_cache)
61 kmem_cache_destroy(async_pf_cache);
62 async_pf_cache = NULL;
63}
64
65void 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
72static 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 use_mm(mm);
84 down_read(&mm->mmap_sem);
85 get_user_pages(current, mm, addr, 1, 1, 0, NULL, NULL);
86 up_read(&mm->mmap_sem);
87 kvm_async_page_present_sync(vcpu, apf);
88 unuse_mm(mm);
89
90 spin_lock(&vcpu->async_pf.lock);
91 list_add_tail(&apf->link, &vcpu->async_pf.done);
92 spin_unlock(&vcpu->async_pf.lock);
93
94 /*
95 * apf may be freed by kvm_check_async_pf_completion() after
96 * this point
97 */
98
99 trace_kvm_async_pf_completed(addr, gva);
100
101 if (waitqueue_active(&vcpu->wq))
102 wake_up_interruptible(&vcpu->wq);
103
104 mmput(mm);
105 kvm_put_kvm(vcpu->kvm);
106}
107
108void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
109{
110 /* cancel outstanding work queue item */
111 while (!list_empty(&vcpu->async_pf.queue)) {
112 struct kvm_async_pf *work =
113 list_entry(vcpu->async_pf.queue.next,
114 typeof(*work), queue);
115 list_del(&work->queue);
116
117#ifdef CONFIG_KVM_ASYNC_PF_SYNC
118 flush_work(&work->work);
119#else
120 if (cancel_work_sync(&work->work)) {
121 mmput(work->mm);
122 kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */
123 kmem_cache_free(async_pf_cache, work);
124 }
125#endif
126 }
127
128 spin_lock(&vcpu->async_pf.lock);
129 while (!list_empty(&vcpu->async_pf.done)) {
130 struct kvm_async_pf *work =
131 list_entry(vcpu->async_pf.done.next,
132 typeof(*work), link);
133 list_del(&work->link);
134 kmem_cache_free(async_pf_cache, work);
135 }
136 spin_unlock(&vcpu->async_pf.lock);
137
138 vcpu->async_pf.queued = 0;
139}
140
141void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
142{
143 struct kvm_async_pf *work;
144
145 while (!list_empty_careful(&vcpu->async_pf.done) &&
146 kvm_arch_can_inject_async_page_present(vcpu)) {
147 spin_lock(&vcpu->async_pf.lock);
148 work = list_first_entry(&vcpu->async_pf.done, typeof(*work),
149 link);
150 list_del(&work->link);
151 spin_unlock(&vcpu->async_pf.lock);
152
153 kvm_arch_async_page_ready(vcpu, work);
154 kvm_async_page_present_async(vcpu, work);
155
156 list_del(&work->queue);
157 vcpu->async_pf.queued--;
158 kmem_cache_free(async_pf_cache, work);
159 }
160}
161
162int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva,
163 struct kvm_arch_async_pf *arch)
164{
165 struct kvm_async_pf *work;
166
167 if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
168 return 0;
169
170 /* setup delayed work */
171
172 /*
173 * do alloc nowait since if we are going to sleep anyway we
174 * may as well sleep faulting in page
175 */
176 work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT);
177 if (!work)
178 return 0;
179
180 work->wakeup_all = false;
181 work->vcpu = vcpu;
182 work->gva = gva;
183 work->addr = hva;
184 work->arch = *arch;
185 work->mm = current->mm;
186 atomic_inc(&work->mm->mm_users);
187 kvm_get_kvm(work->vcpu->kvm);
188
189 /* this can't really happen otherwise gfn_to_pfn_async
190 would succeed */
191 if (unlikely(kvm_is_error_hva(work->addr)))
192 goto retry_sync;
193
194 INIT_WORK(&work->work, async_pf_execute);
195 if (!schedule_work(&work->work))
196 goto retry_sync;
197
198 list_add_tail(&work->queue, &vcpu->async_pf.queue);
199 vcpu->async_pf.queued++;
200 kvm_arch_async_page_not_present(vcpu, work);
201 return 1;
202retry_sync:
203 kvm_put_kvm(work->vcpu->kvm);
204 mmput(work->mm);
205 kmem_cache_free(async_pf_cache, work);
206 return 0;
207}
208
209int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
210{
211 struct kvm_async_pf *work;
212
213 if (!list_empty_careful(&vcpu->async_pf.done))
214 return 0;
215
216 work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
217 if (!work)
218 return -ENOMEM;
219
220 work->wakeup_all = true;
221 INIT_LIST_HEAD(&work->queue); /* for list_del to work */
222
223 spin_lock(&vcpu->async_pf.lock);
224 list_add_tail(&work->link, &vcpu->async_pf.done);
225 spin_unlock(&vcpu->async_pf.lock);
226
227 vcpu->async_pf.queued++;
228 return 0;
229}
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#include <linux/sched/mm.h>
28
29#include "async_pf.h"
30#include <trace/events/kvm.h>
31
32static inline void kvm_async_page_present_sync(struct kvm_vcpu *vcpu,
33 struct kvm_async_pf *work)
34{
35#ifdef CONFIG_KVM_ASYNC_PF_SYNC
36 kvm_arch_async_page_present(vcpu, work);
37#endif
38}
39static inline void kvm_async_page_present_async(struct kvm_vcpu *vcpu,
40 struct kvm_async_pf *work)
41{
42#ifndef CONFIG_KVM_ASYNC_PF_SYNC
43 kvm_arch_async_page_present(vcpu, work);
44#endif
45}
46
47static struct kmem_cache *async_pf_cache;
48
49int kvm_async_pf_init(void)
50{
51 async_pf_cache = KMEM_CACHE(kvm_async_pf, 0);
52
53 if (!async_pf_cache)
54 return -ENOMEM;
55
56 return 0;
57}
58
59void kvm_async_pf_deinit(void)
60{
61 kmem_cache_destroy(async_pf_cache);
62 async_pf_cache = NULL;
63}
64
65void 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
72static 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 int locked = 1;
81
82 might_sleep();
83
84 /*
85 * This work is run asynchromously to the task which owns
86 * mm and might be done in another context, so we must
87 * access remotely.
88 */
89 down_read(&mm->mmap_sem);
90 get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE, NULL, NULL,
91 &locked);
92 if (locked)
93 up_read(&mm->mmap_sem);
94
95 kvm_async_page_present_sync(vcpu, apf);
96
97 spin_lock(&vcpu->async_pf.lock);
98 list_add_tail(&apf->link, &vcpu->async_pf.done);
99 apf->vcpu = NULL;
100 spin_unlock(&vcpu->async_pf.lock);
101
102 /*
103 * apf may be freed by kvm_check_async_pf_completion() after
104 * this point
105 */
106
107 trace_kvm_async_pf_completed(addr, gva);
108
109 if (swq_has_sleeper(&vcpu->wq))
110 swake_up(&vcpu->wq);
111
112 mmput(mm);
113 kvm_put_kvm(vcpu->kvm);
114}
115
116void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
117{
118 spin_lock(&vcpu->async_pf.lock);
119
120 /* cancel outstanding work queue item */
121 while (!list_empty(&vcpu->async_pf.queue)) {
122 struct kvm_async_pf *work =
123 list_first_entry(&vcpu->async_pf.queue,
124 typeof(*work), queue);
125 list_del(&work->queue);
126
127 /*
128 * We know it's present in vcpu->async_pf.done, do
129 * nothing here.
130 */
131 if (!work->vcpu)
132 continue;
133
134 spin_unlock(&vcpu->async_pf.lock);
135#ifdef CONFIG_KVM_ASYNC_PF_SYNC
136 flush_work(&work->work);
137#else
138 if (cancel_work_sync(&work->work)) {
139 mmput(work->mm);
140 kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */
141 kmem_cache_free(async_pf_cache, work);
142 }
143#endif
144 spin_lock(&vcpu->async_pf.lock);
145 }
146
147 while (!list_empty(&vcpu->async_pf.done)) {
148 struct kvm_async_pf *work =
149 list_first_entry(&vcpu->async_pf.done,
150 typeof(*work), link);
151 list_del(&work->link);
152 kmem_cache_free(async_pf_cache, work);
153 }
154 spin_unlock(&vcpu->async_pf.lock);
155
156 vcpu->async_pf.queued = 0;
157}
158
159void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
160{
161 struct kvm_async_pf *work;
162
163 while (!list_empty_careful(&vcpu->async_pf.done) &&
164 kvm_arch_can_inject_async_page_present(vcpu)) {
165 spin_lock(&vcpu->async_pf.lock);
166 work = list_first_entry(&vcpu->async_pf.done, typeof(*work),
167 link);
168 list_del(&work->link);
169 spin_unlock(&vcpu->async_pf.lock);
170
171 kvm_arch_async_page_ready(vcpu, work);
172 kvm_async_page_present_async(vcpu, work);
173
174 list_del(&work->queue);
175 vcpu->async_pf.queued--;
176 kmem_cache_free(async_pf_cache, work);
177 }
178}
179
180int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva,
181 struct kvm_arch_async_pf *arch)
182{
183 struct kvm_async_pf *work;
184
185 if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
186 return 0;
187
188 /* setup delayed work */
189
190 /*
191 * do alloc nowait since if we are going to sleep anyway we
192 * may as well sleep faulting in page
193 */
194 work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT | __GFP_NOWARN);
195 if (!work)
196 return 0;
197
198 work->wakeup_all = false;
199 work->vcpu = vcpu;
200 work->gva = gva;
201 work->addr = hva;
202 work->arch = *arch;
203 work->mm = current->mm;
204 mmget(work->mm);
205 kvm_get_kvm(work->vcpu->kvm);
206
207 /* this can't really happen otherwise gfn_to_pfn_async
208 would succeed */
209 if (unlikely(kvm_is_error_hva(work->addr)))
210 goto retry_sync;
211
212 INIT_WORK(&work->work, async_pf_execute);
213 if (!schedule_work(&work->work))
214 goto retry_sync;
215
216 list_add_tail(&work->queue, &vcpu->async_pf.queue);
217 vcpu->async_pf.queued++;
218 kvm_arch_async_page_not_present(vcpu, work);
219 return 1;
220retry_sync:
221 kvm_put_kvm(work->vcpu->kvm);
222 mmput(work->mm);
223 kmem_cache_free(async_pf_cache, work);
224 return 0;
225}
226
227int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
228{
229 struct kvm_async_pf *work;
230
231 if (!list_empty_careful(&vcpu->async_pf.done))
232 return 0;
233
234 work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
235 if (!work)
236 return -ENOMEM;
237
238 work->wakeup_all = true;
239 INIT_LIST_HEAD(&work->queue); /* for list_del to work */
240
241 spin_lock(&vcpu->async_pf.lock);
242 list_add_tail(&work->link, &vcpu->async_pf.done);
243 spin_unlock(&vcpu->async_pf.lock);
244
245 vcpu->async_pf.queued++;
246 return 0;
247}