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-rw-r--r--virt/kvm/async_pf.c190
1 files changed, 190 insertions, 0 deletions
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
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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 if (list_empty_careful(&vcpu->async_pf.done))
128 return;
129
130 spin_lock(&vcpu->async_pf.lock);
131 work = list_first_entry(&vcpu->async_pf.done, typeof(*work), link);
132 list_del(&work->link);
133 spin_unlock(&vcpu->async_pf.lock);
134
135 kvm_arch_async_page_present(vcpu, work);
136
137 list_del(&work->queue);
138 vcpu->async_pf.queued--;
139 if (work->page)
140 put_page(work->page);
141 kmem_cache_free(async_pf_cache, work);
142}
143
144int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn,
145 struct kvm_arch_async_pf *arch)
146{
147 struct kvm_async_pf *work;
148
149 if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
150 return 0;
151
152 /* setup delayed work */
153
154 /*
155 * do alloc nowait since if we are going to sleep anyway we
156 * may as well sleep faulting in page
157 */
158 work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT);
159 if (!work)
160 return 0;
161
162 work->page = NULL;
163 work->done = false;
164 work->vcpu = vcpu;
165 work->gva = gva;
166 work->addr = gfn_to_hva(vcpu->kvm, gfn);
167 work->arch = *arch;
168 work->mm = current->mm;
169 atomic_inc(&work->mm->mm_count);
170 kvm_get_kvm(work->vcpu->kvm);
171
172 /* this can't really happen otherwise gfn_to_pfn_async
173 would succeed */
174 if (unlikely(kvm_is_error_hva(work->addr)))
175 goto retry_sync;
176
177 INIT_WORK(&work->work, async_pf_execute);
178 if (!schedule_work(&work->work))
179 goto retry_sync;
180
181 list_add_tail(&work->queue, &vcpu->async_pf.queue);
182 vcpu->async_pf.queued++;
183 kvm_arch_async_page_not_present(vcpu, work);
184 return 1;
185retry_sync:
186 kvm_put_kvm(work->vcpu->kvm);
187 mmdrop(work->mm);
188 kmem_cache_free(async_pf_cache, work);
189 return 0;
190}