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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// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * kvm asynchronous fault support
4 *
5 * Copyright 2010 Red Hat, Inc.
6 *
7 * Author:
8 * Gleb Natapov <gleb@redhat.com>
9 */
10
11#include <linux/kvm_host.h>
12#include <linux/slab.h>
13#include <linux/module.h>
14#include <linux/mmu_context.h>
15#include <linux/sched/mm.h>
16
17#include "async_pf.h"
18#include <trace/events/kvm.h>
19
20static struct kmem_cache *async_pf_cache;
21
22int kvm_async_pf_init(void)
23{
24 async_pf_cache = KMEM_CACHE(kvm_async_pf, 0);
25
26 if (!async_pf_cache)
27 return -ENOMEM;
28
29 return 0;
30}
31
32void kvm_async_pf_deinit(void)
33{
34 kmem_cache_destroy(async_pf_cache);
35 async_pf_cache = NULL;
36}
37
38void kvm_async_pf_vcpu_init(struct kvm_vcpu *vcpu)
39{
40 INIT_LIST_HEAD(&vcpu->async_pf.done);
41 INIT_LIST_HEAD(&vcpu->async_pf.queue);
42 spin_lock_init(&vcpu->async_pf.lock);
43}
44
45static void async_pf_execute(struct work_struct *work)
46{
47 struct kvm_async_pf *apf =
48 container_of(work, struct kvm_async_pf, work);
49 struct mm_struct *mm = apf->mm;
50 struct kvm_vcpu *vcpu = apf->vcpu;
51 unsigned long addr = apf->addr;
52 gpa_t cr2_or_gpa = apf->cr2_or_gpa;
53 int locked = 1;
54 bool first;
55
56 might_sleep();
57
58 /*
59 * This work is run asynchronously to the task which owns
60 * mm and might be done in another context, so we must
61 * access remotely.
62 */
63 mmap_read_lock(mm);
64 get_user_pages_remote(mm, addr, 1, FOLL_WRITE, NULL, NULL,
65 &locked);
66 if (locked)
67 mmap_read_unlock(mm);
68
69 if (IS_ENABLED(CONFIG_KVM_ASYNC_PF_SYNC))
70 kvm_arch_async_page_present(vcpu, apf);
71
72 spin_lock(&vcpu->async_pf.lock);
73 first = list_empty(&vcpu->async_pf.done);
74 list_add_tail(&apf->link, &vcpu->async_pf.done);
75 apf->vcpu = NULL;
76 spin_unlock(&vcpu->async_pf.lock);
77
78 if (!IS_ENABLED(CONFIG_KVM_ASYNC_PF_SYNC) && first)
79 kvm_arch_async_page_present_queued(vcpu);
80
81 /*
82 * apf may be freed by kvm_check_async_pf_completion() after
83 * this point
84 */
85
86 trace_kvm_async_pf_completed(addr, cr2_or_gpa);
87
88 __kvm_vcpu_wake_up(vcpu);
89
90 mmput(mm);
91 kvm_put_kvm(vcpu->kvm);
92}
93
94void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
95{
96 spin_lock(&vcpu->async_pf.lock);
97
98 /* cancel outstanding work queue item */
99 while (!list_empty(&vcpu->async_pf.queue)) {
100 struct kvm_async_pf *work =
101 list_first_entry(&vcpu->async_pf.queue,
102 typeof(*work), queue);
103 list_del(&work->queue);
104
105 /*
106 * We know it's present in vcpu->async_pf.done, do
107 * nothing here.
108 */
109 if (!work->vcpu)
110 continue;
111
112 spin_unlock(&vcpu->async_pf.lock);
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 spin_lock(&vcpu->async_pf.lock);
123 }
124
125 while (!list_empty(&vcpu->async_pf.done)) {
126 struct kvm_async_pf *work =
127 list_first_entry(&vcpu->async_pf.done,
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
137void 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_dequeue_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 if (!IS_ENABLED(CONFIG_KVM_ASYNC_PF_SYNC))
151 kvm_arch_async_page_present(vcpu, work);
152
153 list_del(&work->queue);
154 vcpu->async_pf.queued--;
155 kmem_cache_free(async_pf_cache, work);
156 }
157}
158
159/*
160 * Try to schedule a job to handle page fault asynchronously. Returns 'true' on
161 * success, 'false' on failure (page fault has to be handled synchronously).
162 */
163bool kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
164 unsigned long hva, struct kvm_arch_async_pf *arch)
165{
166 struct kvm_async_pf *work;
167
168 if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
169 return false;
170
171 /* Arch specific code should not do async PF in this case */
172 if (unlikely(kvm_is_error_hva(hva)))
173 return false;
174
175 /*
176 * do alloc nowait since if we are going to sleep anyway we
177 * may as well sleep faulting in page
178 */
179 work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT | __GFP_NOWARN);
180 if (!work)
181 return false;
182
183 work->wakeup_all = false;
184 work->vcpu = vcpu;
185 work->cr2_or_gpa = cr2_or_gpa;
186 work->addr = hva;
187 work->arch = *arch;
188 work->mm = current->mm;
189 mmget(work->mm);
190 kvm_get_kvm(work->vcpu->kvm);
191
192 INIT_WORK(&work->work, async_pf_execute);
193
194 list_add_tail(&work->queue, &vcpu->async_pf.queue);
195 vcpu->async_pf.queued++;
196 work->notpresent_injected = kvm_arch_async_page_not_present(vcpu, work);
197
198 schedule_work(&work->work);
199
200 return true;
201}
202
203int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
204{
205 struct kvm_async_pf *work;
206 bool first;
207
208 if (!list_empty_careful(&vcpu->async_pf.done))
209 return 0;
210
211 work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
212 if (!work)
213 return -ENOMEM;
214
215 work->wakeup_all = true;
216 INIT_LIST_HEAD(&work->queue); /* for list_del to work */
217
218 spin_lock(&vcpu->async_pf.lock);
219 first = list_empty(&vcpu->async_pf.done);
220 list_add_tail(&work->link, &vcpu->async_pf.done);
221 spin_unlock(&vcpu->async_pf.lock);
222
223 if (!IS_ENABLED(CONFIG_KVM_ASYNC_PF_SYNC) && first)
224 kvm_arch_async_page_present_queued(vcpu);
225
226 vcpu->async_pf.queued++;
227 return 0;
228}