Merge tag 'drm-fixes-for-v4.16-rc2' of git://people.freedesktop.org/~airlied/linux
[sfrench/cifs-2.6.git] / virt / kvm / async_pf.c
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 #include <linux/sched/mm.h>
28
29 #include "async_pf.h"
30 #include <trace/events/kvm.h>
31
32 static inline void kvm_async_page_present_sync(struct kvm_vcpu *vcpu,
33                                                struct kvm_async_pf *work)
34 {
35 #ifdef CONFIG_KVM_ASYNC_PF_SYNC
36         kvm_arch_async_page_present(vcpu, work);
37 #endif
38 }
39 static inline void kvm_async_page_present_async(struct kvm_vcpu *vcpu,
40                                                 struct kvm_async_pf *work)
41 {
42 #ifndef CONFIG_KVM_ASYNC_PF_SYNC
43         kvm_arch_async_page_present(vcpu, work);
44 #endif
45 }
46
47 static struct kmem_cache *async_pf_cache;
48
49 int kvm_async_pf_init(void)
50 {
51         async_pf_cache = KMEM_CACHE(kvm_async_pf, 0);
52
53         if (!async_pf_cache)
54                 return -ENOMEM;
55
56         return 0;
57 }
58
59 void kvm_async_pf_deinit(void)
60 {
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         int locked = 1;
81
82         might_sleep();
83
84         /*
85          * This work is run asynchromously to the task which owns
86          * mm and might be done in another context, so we must
87          * access remotely.
88          */
89         down_read(&mm->mmap_sem);
90         get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE, NULL, NULL,
91                         &locked);
92         if (locked)
93                 up_read(&mm->mmap_sem);
94
95         kvm_async_page_present_sync(vcpu, apf);
96
97         spin_lock(&vcpu->async_pf.lock);
98         list_add_tail(&apf->link, &vcpu->async_pf.done);
99         apf->vcpu = NULL;
100         spin_unlock(&vcpu->async_pf.lock);
101
102         /*
103          * apf may be freed by kvm_check_async_pf_completion() after
104          * this point
105          */
106
107         trace_kvm_async_pf_completed(addr, gva);
108
109         if (swq_has_sleeper(&vcpu->wq))
110                 swake_up(&vcpu->wq);
111
112         mmput(mm);
113         kvm_put_kvm(vcpu->kvm);
114 }
115
116 void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
117 {
118         spin_lock(&vcpu->async_pf.lock);
119
120         /* cancel outstanding work queue item */
121         while (!list_empty(&vcpu->async_pf.queue)) {
122                 struct kvm_async_pf *work =
123                         list_first_entry(&vcpu->async_pf.queue,
124                                          typeof(*work), queue);
125                 list_del(&work->queue);
126
127                 /*
128                  * We know it's present in vcpu->async_pf.done, do
129                  * nothing here.
130                  */
131                 if (!work->vcpu)
132                         continue;
133
134                 spin_unlock(&vcpu->async_pf.lock);
135 #ifdef CONFIG_KVM_ASYNC_PF_SYNC
136                 flush_work(&work->work);
137 #else
138                 if (cancel_work_sync(&work->work)) {
139                         mmput(work->mm);
140                         kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */
141                         kmem_cache_free(async_pf_cache, work);
142                 }
143 #endif
144                 spin_lock(&vcpu->async_pf.lock);
145         }
146
147         while (!list_empty(&vcpu->async_pf.done)) {
148                 struct kvm_async_pf *work =
149                         list_first_entry(&vcpu->async_pf.done,
150                                          typeof(*work), link);
151                 list_del(&work->link);
152                 kmem_cache_free(async_pf_cache, work);
153         }
154         spin_unlock(&vcpu->async_pf.lock);
155
156         vcpu->async_pf.queued = 0;
157 }
158
159 void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
160 {
161         struct kvm_async_pf *work;
162
163         while (!list_empty_careful(&vcpu->async_pf.done) &&
164               kvm_arch_can_inject_async_page_present(vcpu)) {
165                 spin_lock(&vcpu->async_pf.lock);
166                 work = list_first_entry(&vcpu->async_pf.done, typeof(*work),
167                                               link);
168                 list_del(&work->link);
169                 spin_unlock(&vcpu->async_pf.lock);
170
171                 kvm_arch_async_page_ready(vcpu, work);
172                 kvm_async_page_present_async(vcpu, work);
173
174                 list_del(&work->queue);
175                 vcpu->async_pf.queued--;
176                 kmem_cache_free(async_pf_cache, work);
177         }
178 }
179
180 int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva,
181                        struct kvm_arch_async_pf *arch)
182 {
183         struct kvm_async_pf *work;
184
185         if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
186                 return 0;
187
188         /* setup delayed work */
189
190         /*
191          * do alloc nowait since if we are going to sleep anyway we
192          * may as well sleep faulting in page
193          */
194         work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT | __GFP_NOWARN);
195         if (!work)
196                 return 0;
197
198         work->wakeup_all = false;
199         work->vcpu = vcpu;
200         work->gva = gva;
201         work->addr = hva;
202         work->arch = *arch;
203         work->mm = current->mm;
204         mmget(work->mm);
205         kvm_get_kvm(work->vcpu->kvm);
206
207         /* this can't really happen otherwise gfn_to_pfn_async
208            would succeed */
209         if (unlikely(kvm_is_error_hva(work->addr)))
210                 goto retry_sync;
211
212         INIT_WORK(&work->work, async_pf_execute);
213         if (!schedule_work(&work->work))
214                 goto retry_sync;
215
216         list_add_tail(&work->queue, &vcpu->async_pf.queue);
217         vcpu->async_pf.queued++;
218         kvm_arch_async_page_not_present(vcpu, work);
219         return 1;
220 retry_sync:
221         kvm_put_kvm(work->vcpu->kvm);
222         mmput(work->mm);
223         kmem_cache_free(async_pf_cache, work);
224         return 0;
225 }
226
227 int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
228 {
229         struct kvm_async_pf *work;
230
231         if (!list_empty_careful(&vcpu->async_pf.done))
232                 return 0;
233
234         work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
235         if (!work)
236                 return -ENOMEM;
237
238         work->wakeup_all = true;
239         INIT_LIST_HEAD(&work->queue); /* for list_del to work */
240
241         spin_lock(&vcpu->async_pf.lock);
242         list_add_tail(&work->link, &vcpu->async_pf.done);
243         spin_unlock(&vcpu->async_pf.lock);
244
245         vcpu->async_pf.queued++;
246         return 0;
247 }