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