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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 struct kmem_cache *async_pf_cache;
32
33int 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
43void 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
50void 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
57static 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;
78 apf->done = true;
79 spin_unlock(&vcpu->async_pf.lock);
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, page, gva);
87
88 if (waitqueue_active(&vcpu->wq))
89 wake_up_interruptible(&vcpu->wq);
90
91 mmdrop(mm);
92 kvm_put_kvm(vcpu->kvm);
93}
94
95void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
96{
97 /* cancel outstanding work queue item */
98 while (!list_empty(&vcpu->async_pf.queue)) {
99 struct kvm_async_pf *work =
100 list_entry(vcpu->async_pf.queue.next,
101 typeof(*work), queue);
102 cancel_work_sync(&work->work);
103 list_del(&work->queue);
104 if (!work->done) /* work was canceled */
105 kmem_cache_free(async_pf_cache, work);
106 }
107
108 spin_lock(&vcpu->async_pf.lock);
109 while (!list_empty(&vcpu->async_pf.done)) {
110 struct kvm_async_pf *work =
111 list_entry(vcpu->async_pf.done.next,
112 typeof(*work), link);
113 list_del(&work->link);
114 if (work->page)
115 put_page(work->page);
116 kmem_cache_free(async_pf_cache, work);
117 }
118 spin_unlock(&vcpu->async_pf.lock);
119
120 vcpu->async_pf.queued = 0;
121}
122
123void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
124{
125 struct kvm_async_pf *work;
126
127 while (!list_empty_careful(&vcpu->async_pf.done) &&
128 kvm_arch_can_inject_async_page_present(vcpu)) {
129 spin_lock(&vcpu->async_pf.lock);
130 work = list_first_entry(&vcpu->async_pf.done, typeof(*work),
131 link);
132 list_del(&work->link);
133 spin_unlock(&vcpu->async_pf.lock);
134
135 if (work->page)
136 kvm_arch_async_page_ready(vcpu, work);
137 kvm_arch_async_page_present(vcpu, work);
138
139 list_del(&work->queue);
140 vcpu->async_pf.queued--;
141 if (work->page)
142 put_page(work->page);
143 kmem_cache_free(async_pf_cache, work);
144 }
145}
146
147int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn,
148 struct kvm_arch_async_pf *arch)
149{
150 struct kvm_async_pf *work;
151
152 if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
153 return 0;
154
155 /* setup delayed work */
156
157 /*
158 * do alloc nowait since if we are going to sleep anyway we
159 * may as well sleep faulting in page
160 */
161 work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT);
162 if (!work)
163 return 0;
164
165 work->page = NULL;
166 work->done = false;
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;
188retry_sync:
189 kvm_put_kvm(work->vcpu->kvm);
190 mmdrop(work->mm);
191 kmem_cache_free(async_pf_cache, work);
192 return 0;
193}
194
195int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
196{
197 struct kvm_async_pf *work;
198
199 if (!list_empty_careful(&vcpu->async_pf.done))
200 return 0;
201
202 work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
203 if (!work)
204 return -ENOMEM;
205
206 work->page = bad_page;
207 get_page(bad_page);
208 INIT_LIST_HEAD(&work->queue); /* for list_del to work */
209
210 spin_lock(&vcpu->async_pf.lock);
211 list_add_tail(&work->link, &vcpu->async_pf.done);
212 spin_unlock(&vcpu->async_pf.lock);
213
214 vcpu->async_pf.queued++;
215 return 0;
216}
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 inline void kvm_async_page_present_sync(struct kvm_vcpu *vcpu,
21 struct kvm_async_pf *work)
22{
23#ifdef CONFIG_KVM_ASYNC_PF_SYNC
24 kvm_arch_async_page_present(vcpu, work);
25#endif
26}
27static inline void kvm_async_page_present_async(struct kvm_vcpu *vcpu,
28 struct kvm_async_pf *work)
29{
30#ifndef CONFIG_KVM_ASYNC_PF_SYNC
31 kvm_arch_async_page_present(vcpu, work);
32#endif
33}
34
35static struct kmem_cache *async_pf_cache;
36
37int kvm_async_pf_init(void)
38{
39 async_pf_cache = KMEM_CACHE(kvm_async_pf, 0);
40
41 if (!async_pf_cache)
42 return -ENOMEM;
43
44 return 0;
45}
46
47void kvm_async_pf_deinit(void)
48{
49 kmem_cache_destroy(async_pf_cache);
50 async_pf_cache = NULL;
51}
52
53void kvm_async_pf_vcpu_init(struct kvm_vcpu *vcpu)
54{
55 INIT_LIST_HEAD(&vcpu->async_pf.done);
56 INIT_LIST_HEAD(&vcpu->async_pf.queue);
57 spin_lock_init(&vcpu->async_pf.lock);
58}
59
60static void async_pf_execute(struct work_struct *work)
61{
62 struct kvm_async_pf *apf =
63 container_of(work, struct kvm_async_pf, work);
64 struct mm_struct *mm = apf->mm;
65 struct kvm_vcpu *vcpu = apf->vcpu;
66 unsigned long addr = apf->addr;
67 gva_t gva = apf->gva;
68 int locked = 1;
69
70 might_sleep();
71
72 /*
73 * This work is run asynchronously to the task which owns
74 * mm and might be done in another context, so we must
75 * access remotely.
76 */
77 down_read(&mm->mmap_sem);
78 get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE, NULL, NULL,
79 &locked);
80 if (locked)
81 up_read(&mm->mmap_sem);
82
83 kvm_async_page_present_sync(vcpu, apf);
84
85 spin_lock(&vcpu->async_pf.lock);
86 list_add_tail(&apf->link, &vcpu->async_pf.done);
87 apf->vcpu = NULL;
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 (swq_has_sleeper(&vcpu->wq))
98 swake_up_one(&vcpu->wq);
99
100 mmput(mm);
101 kvm_put_kvm(vcpu->kvm);
102}
103
104void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
105{
106 spin_lock(&vcpu->async_pf.lock);
107
108 /* cancel outstanding work queue item */
109 while (!list_empty(&vcpu->async_pf.queue)) {
110 struct kvm_async_pf *work =
111 list_first_entry(&vcpu->async_pf.queue,
112 typeof(*work), queue);
113 list_del(&work->queue);
114
115 /*
116 * We know it's present in vcpu->async_pf.done, do
117 * nothing here.
118 */
119 if (!work->vcpu)
120 continue;
121
122 spin_unlock(&vcpu->async_pf.lock);
123#ifdef CONFIG_KVM_ASYNC_PF_SYNC
124 flush_work(&work->work);
125#else
126 if (cancel_work_sync(&work->work)) {
127 mmput(work->mm);
128 kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */
129 kmem_cache_free(async_pf_cache, work);
130 }
131#endif
132 spin_lock(&vcpu->async_pf.lock);
133 }
134
135 while (!list_empty(&vcpu->async_pf.done)) {
136 struct kvm_async_pf *work =
137 list_first_entry(&vcpu->async_pf.done,
138 typeof(*work), link);
139 list_del(&work->link);
140 kmem_cache_free(async_pf_cache, work);
141 }
142 spin_unlock(&vcpu->async_pf.lock);
143
144 vcpu->async_pf.queued = 0;
145}
146
147void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
148{
149 struct kvm_async_pf *work;
150
151 while (!list_empty_careful(&vcpu->async_pf.done) &&
152 kvm_arch_can_inject_async_page_present(vcpu)) {
153 spin_lock(&vcpu->async_pf.lock);
154 work = list_first_entry(&vcpu->async_pf.done, typeof(*work),
155 link);
156 list_del(&work->link);
157 spin_unlock(&vcpu->async_pf.lock);
158
159 kvm_arch_async_page_ready(vcpu, work);
160 kvm_async_page_present_async(vcpu, work);
161
162 list_del(&work->queue);
163 vcpu->async_pf.queued--;
164 kmem_cache_free(async_pf_cache, work);
165 }
166}
167
168int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva,
169 struct kvm_arch_async_pf *arch)
170{
171 struct kvm_async_pf *work;
172
173 if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
174 return 0;
175
176 /* setup delayed work */
177
178 /*
179 * do alloc nowait since if we are going to sleep anyway we
180 * may as well sleep faulting in page
181 */
182 work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT | __GFP_NOWARN);
183 if (!work)
184 return 0;
185
186 work->wakeup_all = false;
187 work->vcpu = vcpu;
188 work->gva = gva;
189 work->addr = hva;
190 work->arch = *arch;
191 work->mm = current->mm;
192 mmget(work->mm);
193 kvm_get_kvm(work->vcpu->kvm);
194
195 /* this can't really happen otherwise gfn_to_pfn_async
196 would succeed */
197 if (unlikely(kvm_is_error_hva(work->addr)))
198 goto retry_sync;
199
200 INIT_WORK(&work->work, async_pf_execute);
201 if (!schedule_work(&work->work))
202 goto retry_sync;
203
204 list_add_tail(&work->queue, &vcpu->async_pf.queue);
205 vcpu->async_pf.queued++;
206 kvm_arch_async_page_not_present(vcpu, work);
207 return 1;
208retry_sync:
209 kvm_put_kvm(work->vcpu->kvm);
210 mmput(work->mm);
211 kmem_cache_free(async_pf_cache, work);
212 return 0;
213}
214
215int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
216{
217 struct kvm_async_pf *work;
218
219 if (!list_empty_careful(&vcpu->async_pf.done))
220 return 0;
221
222 work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
223 if (!work)
224 return -ENOMEM;
225
226 work->wakeup_all = true;
227 INIT_LIST_HEAD(&work->queue); /* for list_del to work */
228
229 spin_lock(&vcpu->async_pf.lock);
230 list_add_tail(&work->link, &vcpu->async_pf.done);
231 spin_unlock(&vcpu->async_pf.lock);
232
233 vcpu->async_pf.queued++;
234 return 0;
235}