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 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 } 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 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 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 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 81 might_sleep(); 82 83 get_user_pages_unlocked(NULL, mm, addr, 1, 1, 0, NULL); 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 } 107 108 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 } 140 141 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 } 161 162 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); 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 } 208 209 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