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
kvm_async_page_present_sync(struct kvm_vcpu * vcpu,struct kvm_async_pf * work)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 }
kvm_async_page_present_async(struct kvm_vcpu * vcpu,struct kvm_async_pf * work)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
kvm_async_pf_init(void)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
kvm_async_pf_deinit(void)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
kvm_async_pf_vcpu_init(struct kvm_vcpu * vcpu)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
async_pf_execute(struct work_struct * work)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 get_user_pages_unlocked(NULL, mm, addr, 1, NULL, FOLL_WRITE);
84 kvm_async_page_present_sync(vcpu, apf);
85
86 spin_lock(&vcpu->async_pf.lock);
87 list_add_tail(&apf->link, &vcpu->async_pf.done);
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 /*
98 * This memory barrier pairs with prepare_to_wait's set_current_state()
99 */
100 smp_mb();
101 if (waitqueue_active(&vcpu->wq))
102 wake_up_interruptible(&vcpu->wq);
103
104 mmput(mm);
105 kvm_put_kvm(vcpu->kvm);
106 }
107
kvm_clear_async_pf_completion_queue(struct kvm_vcpu * vcpu)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
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
kvm_check_async_pf_completion(struct kvm_vcpu * vcpu)141 void 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
kvm_setup_async_pf(struct kvm_vcpu * vcpu,gva_t gva,unsigned long hva,struct kvm_arch_async_pf * arch)162 int 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 | __GFP_NOWARN);
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;
202 retry_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
kvm_async_pf_wakeup_all(struct kvm_vcpu * vcpu)209 int 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 }
230