1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* kvm asynchronous fault support
*
* Copyright 2010 Red Hat, Inc.
*
* Author:
* Gleb Natapov <gleb@redhat.com>
*/
#include <linux/kvm_host.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/mmu_context.h>
#include <linux/sched/mm.h>
#include "async_pf.h"
#include <trace/events/kvm.h>
static struct kmem_cache *async_pf_cache;
int kvm_async_pf_init(void)
{
async_pf_cache = KMEM_CACHE(kvm_async_pf, 0);
if (!async_pf_cache)
return -ENOMEM;
return 0;
}
void kvm_async_pf_deinit(void)
{
kmem_cache_destroy(async_pf_cache);
async_pf_cache = NULL;
}
void kvm_async_pf_vcpu_init(struct kvm_vcpu *vcpu)
{
INIT_LIST_HEAD(&vcpu->async_pf.done);
INIT_LIST_HEAD(&vcpu->async_pf.queue);
spin_lock_init(&vcpu->async_pf.lock);
}
static void async_pf_execute(struct work_struct *work)
{
struct kvm_async_pf *apf =
container_of(work, struct kvm_async_pf, work);
struct mm_struct *mm = apf->mm;
struct kvm_vcpu *vcpu = apf->vcpu;
unsigned long addr = apf->addr;
gpa_t cr2_or_gpa = apf->cr2_or_gpa;
int locked = 1;
bool first;
might_sleep();
/*
* This work is run asynchronously to the task which owns
* mm and might be done in another context, so we must
* access remotely.
*/
mmap_read_lock(mm);
get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE, NULL, NULL,
&locked);
if (locked)
mmap_read_unlock(mm);
if (IS_ENABLED(CONFIG_KVM_ASYNC_PF_SYNC))
kvm_arch_async_page_present(vcpu, apf);
spin_lock(&vcpu->async_pf.lock);
first = list_empty(&vcpu->async_pf.done);
list_add_tail(&apf->link, &vcpu->async_pf.done);
apf->vcpu = NULL;
spin_unlock(&vcpu->async_pf.lock);
if (!IS_ENABLED(CONFIG_KVM_ASYNC_PF_SYNC) && first)
kvm_arch_async_page_present_queued(vcpu);
/*
* apf may be freed by kvm_check_async_pf_completion() after
* this point
*/
trace_kvm_async_pf_completed(addr, cr2_or_gpa);
rcuwait_wake_up(&vcpu->wait);
mmput(mm);
kvm_put_kvm(vcpu->kvm);
}
void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
{
spin_lock(&vcpu->async_pf.lock);
/* cancel outstanding work queue item */
while (!list_empty(&vcpu->async_pf.queue)) {
struct kvm_async_pf *work =
list_first_entry(&vcpu->async_pf.queue,
typeof(*work), queue);
list_del(&work->queue);
/*
* We know it's present in vcpu->async_pf.done, do
* nothing here.
*/
if (!work->vcpu)
continue;
spin_unlock(&vcpu->async_pf.lock);
#ifdef CONFIG_KVM_ASYNC_PF_SYNC
flush_work(&work->work);
#else
if (cancel_work_sync(&work->work)) {
mmput(work->mm);
kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */
kmem_cache_free(async_pf_cache, work);
}
#endif
spin_lock(&vcpu->async_pf.lock);
}
while (!list_empty(&vcpu->async_pf.done)) {
struct kvm_async_pf *work =
list_first_entry(&vcpu->async_pf.done,
typeof(*work), link);
list_del(&work->link);
kmem_cache_free(async_pf_cache, work);
}
spin_unlock(&vcpu->async_pf.lock);
vcpu->async_pf.queued = 0;
}
void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
{
struct kvm_async_pf *work;
while (!list_empty_careful(&vcpu->async_pf.done) &&
kvm_arch_can_dequeue_async_page_present(vcpu)) {
spin_lock(&vcpu->async_pf.lock);
work = list_first_entry(&vcpu->async_pf.done, typeof(*work),
link);
list_del(&work->link);
spin_unlock(&vcpu->async_pf.lock);
kvm_arch_async_page_ready(vcpu, work);
if (!IS_ENABLED(CONFIG_KVM_ASYNC_PF_SYNC))
kvm_arch_async_page_present(vcpu, work);
list_del(&work->queue);
vcpu->async_pf.queued--;
kmem_cache_free(async_pf_cache, work);
}
}
/*
* Try to schedule a job to handle page fault asynchronously. Returns 'true' on
* success, 'false' on failure (page fault has to be handled synchronously).
*/
bool kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
unsigned long hva, struct kvm_arch_async_pf *arch)
{
struct kvm_async_pf *work;
if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
return false;
/* Arch specific code should not do async PF in this case */
if (unlikely(kvm_is_error_hva(hva)))
return false;
/*
* do alloc nowait since if we are going to sleep anyway we
* may as well sleep faulting in page
*/
work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT | __GFP_NOWARN);
if (!work)
return false;
work->wakeup_all = false;
work->vcpu = vcpu;
work->cr2_or_gpa = cr2_or_gpa;
work->addr = hva;
work->arch = *arch;
work->mm = current->mm;
mmget(work->mm);
kvm_get_kvm(work->vcpu->kvm);
INIT_WORK(&work->work, async_pf_execute);
list_add_tail(&work->queue, &vcpu->async_pf.queue);
vcpu->async_pf.queued++;
work->notpresent_injected = kvm_arch_async_page_not_present(vcpu, work);
schedule_work(&work->work);
return true;
}
int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
{
struct kvm_async_pf *work;
bool first;
if (!list_empty_careful(&vcpu->async_pf.done))
return 0;
work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
if (!work)
return -ENOMEM;
work->wakeup_all = true;
INIT_LIST_HEAD(&work->queue); /* for list_del to work */
spin_lock(&vcpu->async_pf.lock);
first = list_empty(&vcpu->async_pf.done);
list_add_tail(&work->link, &vcpu->async_pf.done);
spin_unlock(&vcpu->async_pf.lock);
if (!IS_ENABLED(CONFIG_KVM_ASYNC_PF_SYNC) && first)
kvm_arch_async_page_present_queued(vcpu);
vcpu->async_pf.queued++;
return 0;
}
|
