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 31 static struct kmem_cache *async_pf_cache; 32 33 int 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 43 void 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 50 void 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 57 static void async_pf_execute(struct work_struct *work) 58 { 59 struct kvm_async_pf *apf = 60 container_of(work, struct kvm_async_pf, work); 61 struct mm_struct *mm = apf->mm; 62 struct kvm_vcpu *vcpu = apf->vcpu; 63 unsigned long addr = apf->addr; 64 gva_t gva = apf->gva; 65 66 might_sleep(); 67 68 use_mm(mm); 69 down_read(&mm->mmap_sem); 70 get_user_pages(current, mm, addr, 1, 1, 0, NULL, NULL); 71 up_read(&mm->mmap_sem); 72 unuse_mm(mm); 73 74 spin_lock(&vcpu->async_pf.lock); 75 list_add_tail(&apf->link, &vcpu->async_pf.done); 76 spin_unlock(&vcpu->async_pf.lock); 77 78 /* 79 * apf may be freed by kvm_check_async_pf_completion() after 80 * this point 81 */ 82 83 trace_kvm_async_pf_completed(addr, gva); 84 85 if (waitqueue_active(&vcpu->wq)) 86 wake_up_interruptible(&vcpu->wq); 87 88 mmdrop(mm); 89 kvm_put_kvm(vcpu->kvm); 90 } 91 92 void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu) 93 { 94 /* cancel outstanding work queue item */ 95 while (!list_empty(&vcpu->async_pf.queue)) { 96 struct kvm_async_pf *work = 97 list_entry(vcpu->async_pf.queue.next, 98 typeof(*work), queue); 99 list_del(&work->queue); 100 if (cancel_work_sync(&work->work)) { 101 mmdrop(work->mm); 102 kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */ 103 kmem_cache_free(async_pf_cache, work); 104 } 105 } 106 107 spin_lock(&vcpu->async_pf.lock); 108 while (!list_empty(&vcpu->async_pf.done)) { 109 struct kvm_async_pf *work = 110 list_entry(vcpu->async_pf.done.next, 111 typeof(*work), link); 112 list_del(&work->link); 113 kmem_cache_free(async_pf_cache, work); 114 } 115 spin_unlock(&vcpu->async_pf.lock); 116 117 vcpu->async_pf.queued = 0; 118 } 119 120 void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu) 121 { 122 struct kvm_async_pf *work; 123 124 while (!list_empty_careful(&vcpu->async_pf.done) && 125 kvm_arch_can_inject_async_page_present(vcpu)) { 126 spin_lock(&vcpu->async_pf.lock); 127 work = list_first_entry(&vcpu->async_pf.done, typeof(*work), 128 link); 129 list_del(&work->link); 130 spin_unlock(&vcpu->async_pf.lock); 131 132 kvm_arch_async_page_ready(vcpu, work); 133 kvm_arch_async_page_present(vcpu, work); 134 135 list_del(&work->queue); 136 vcpu->async_pf.queued--; 137 kmem_cache_free(async_pf_cache, work); 138 } 139 } 140 141 int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn, 142 struct kvm_arch_async_pf *arch) 143 { 144 struct kvm_async_pf *work; 145 146 if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU) 147 return 0; 148 149 /* setup delayed work */ 150 151 /* 152 * do alloc nowait since if we are going to sleep anyway we 153 * may as well sleep faulting in page 154 */ 155 work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT); 156 if (!work) 157 return 0; 158 159 work->wakeup_all = false; 160 work->vcpu = vcpu; 161 work->gva = gva; 162 work->addr = gfn_to_hva(vcpu->kvm, gfn); 163 work->arch = *arch; 164 work->mm = current->mm; 165 atomic_inc(&work->mm->mm_count); 166 kvm_get_kvm(work->vcpu->kvm); 167 168 /* this can't really happen otherwise gfn_to_pfn_async 169 would succeed */ 170 if (unlikely(kvm_is_error_hva(work->addr))) 171 goto retry_sync; 172 173 INIT_WORK(&work->work, async_pf_execute); 174 if (!schedule_work(&work->work)) 175 goto retry_sync; 176 177 list_add_tail(&work->queue, &vcpu->async_pf.queue); 178 vcpu->async_pf.queued++; 179 kvm_arch_async_page_not_present(vcpu, work); 180 return 1; 181 retry_sync: 182 kvm_put_kvm(work->vcpu->kvm); 183 mmdrop(work->mm); 184 kmem_cache_free(async_pf_cache, work); 185 return 0; 186 } 187 188 int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu) 189 { 190 struct kvm_async_pf *work; 191 192 if (!list_empty_careful(&vcpu->async_pf.done)) 193 return 0; 194 195 work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC); 196 if (!work) 197 return -ENOMEM; 198 199 work->wakeup_all = true; 200 INIT_LIST_HEAD(&work->queue); /* for list_del to work */ 201 202 spin_lock(&vcpu->async_pf.lock); 203 list_add_tail(&work->link, &vcpu->async_pf.done); 204 spin_unlock(&vcpu->async_pf.lock); 205 206 vcpu->async_pf.queued++; 207 return 0; 208 } 209