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KVM: async_pf: Provide additional direct page notification
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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 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 mmdrop(mm);
105 kvm_put_kvm(vcpu->kvm);
106 }
107
108 void 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 if (cancel_work_sync(&work->work)) {
117 mmdrop(work->mm);
118 kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */
119 kmem_cache_free(async_pf_cache, work);
120 }
121 }
122
123 spin_lock(&vcpu->async_pf.lock);
124 while (!list_empty(&vcpu->async_pf.done)) {
125 struct kvm_async_pf *work =
126 list_entry(vcpu->async_pf.done.next,
127 typeof(*work), link);
128 list_del(&work->link);
129 kmem_cache_free(async_pf_cache, work);
130 }
131 spin_unlock(&vcpu->async_pf.lock);
132
133 vcpu->async_pf.queued = 0;
134 }
135
136 void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
137 {
138 struct kvm_async_pf *work;
139
140 while (!list_empty_careful(&vcpu->async_pf.done) &&
141 kvm_arch_can_inject_async_page_present(vcpu)) {
142 spin_lock(&vcpu->async_pf.lock);
143 work = list_first_entry(&vcpu->async_pf.done, typeof(*work),
144 link);
145 list_del(&work->link);
146 spin_unlock(&vcpu->async_pf.lock);
147
148 kvm_arch_async_page_ready(vcpu, work);
149 kvm_arch_async_page_present(vcpu, work);
150
151 list_del(&work->queue);
152 vcpu->async_pf.queued--;
153 kmem_cache_free(async_pf_cache, work);
154 }
155 }
156
157 int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva,
158 struct kvm_arch_async_pf *arch)
159 {
160 struct kvm_async_pf *work;
161
162 if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
163 return 0;
164
165 /* setup delayed work */
166
167 /*
168 * do alloc nowait since if we are going to sleep anyway we
169 * may as well sleep faulting in page
170 */
171 work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT);
172 if (!work)
173 return 0;
174
175 work->wakeup_all = false;
176 work->vcpu = vcpu;
177 work->gva = gva;
178 work->addr = hva;
179 work->arch = *arch;
180 work->mm = current->mm;
181 atomic_inc(&work->mm->mm_count);
182 kvm_get_kvm(work->vcpu->kvm);
183
184 /* this can't really happen otherwise gfn_to_pfn_async
185 would succeed */
186 if (unlikely(kvm_is_error_hva(work->addr)))
187 goto retry_sync;
188
189 INIT_WORK(&work->work, async_pf_execute);
190 if (!schedule_work(&work->work))
191 goto retry_sync;
192
193 list_add_tail(&work->queue, &vcpu->async_pf.queue);
194 vcpu->async_pf.queued++;
195 kvm_arch_async_page_not_present(vcpu, work);
196 return 1;
197 retry_sync:
198 kvm_put_kvm(work->vcpu->kvm);
199 mmdrop(work->mm);
200 kmem_cache_free(async_pf_cache, work);
201 return 0;
202 }
203
204 int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
205 {
206 struct kvm_async_pf *work;
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 list_add_tail(&work->link, &vcpu->async_pf.done);
220 spin_unlock(&vcpu->async_pf.lock);
221
222 vcpu->async_pf.queued++;
223 return 0;
224 }