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 kmem_cache_destroy(async_pf_cache); 61 async_pf_cache = NULL; 62 } 63 64 void kvm_async_pf_vcpu_init(struct kvm_vcpu *vcpu) 65 { 66 INIT_LIST_HEAD(&vcpu->async_pf.done); 67 INIT_LIST_HEAD(&vcpu->async_pf.queue); 68 spin_lock_init(&vcpu->async_pf.lock); 69 } 70 71 static void async_pf_execute(struct work_struct *work) 72 { 73 struct kvm_async_pf *apf = 74 container_of(work, struct kvm_async_pf, work); 75 struct mm_struct *mm = apf->mm; 76 struct kvm_vcpu *vcpu = apf->vcpu; 77 unsigned long addr = apf->addr; 78 gva_t gva = apf->gva; 79 80 might_sleep(); 81 82 get_user_pages_unlocked(NULL, mm, addr, 1, 1, 0, NULL); 83 kvm_async_page_present_sync(vcpu, apf); 84 85 spin_lock(&vcpu->async_pf.lock); 86 list_add_tail(&apf->link, &vcpu->async_pf.done); 87 spin_unlock(&vcpu->async_pf.lock); 88 89 /* 90 * apf may be freed by kvm_check_async_pf_completion() after 91 * this point 92 */ 93 94 trace_kvm_async_pf_completed(addr, gva); 95 96 /* 97 * This memory barrier pairs with prepare_to_wait's set_current_state() 98 */ 99 smp_mb(); 100 if (waitqueue_active(&vcpu->wq)) 101 wake_up_interruptible(&vcpu->wq); 102 103 mmput(mm); 104 kvm_put_kvm(vcpu->kvm); 105 } 106 107 void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu) 108 { 109 /* cancel outstanding work queue item */ 110 while (!list_empty(&vcpu->async_pf.queue)) { 111 struct kvm_async_pf *work = 112 list_entry(vcpu->async_pf.queue.next, 113 typeof(*work), queue); 114 list_del(&work->queue); 115 116 #ifdef CONFIG_KVM_ASYNC_PF_SYNC 117 flush_work(&work->work); 118 #else 119 if (cancel_work_sync(&work->work)) { 120 mmput(work->mm); 121 kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */ 122 kmem_cache_free(async_pf_cache, work); 123 } 124 #endif 125 } 126 127 spin_lock(&vcpu->async_pf.lock); 128 while (!list_empty(&vcpu->async_pf.done)) { 129 struct kvm_async_pf *work = 130 list_entry(vcpu->async_pf.done.next, 131 typeof(*work), link); 132 list_del(&work->link); 133 kmem_cache_free(async_pf_cache, work); 134 } 135 spin_unlock(&vcpu->async_pf.lock); 136 137 vcpu->async_pf.queued = 0; 138 } 139 140 void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu) 141 { 142 struct kvm_async_pf *work; 143 144 while (!list_empty_careful(&vcpu->async_pf.done) && 145 kvm_arch_can_inject_async_page_present(vcpu)) { 146 spin_lock(&vcpu->async_pf.lock); 147 work = list_first_entry(&vcpu->async_pf.done, typeof(*work), 148 link); 149 list_del(&work->link); 150 spin_unlock(&vcpu->async_pf.lock); 151 152 kvm_arch_async_page_ready(vcpu, work); 153 kvm_async_page_present_async(vcpu, work); 154 155 list_del(&work->queue); 156 vcpu->async_pf.queued--; 157 kmem_cache_free(async_pf_cache, work); 158 } 159 } 160 161 int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva, 162 struct kvm_arch_async_pf *arch) 163 { 164 struct kvm_async_pf *work; 165 166 if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU) 167 return 0; 168 169 /* setup delayed work */ 170 171 /* 172 * do alloc nowait since if we are going to sleep anyway we 173 * may as well sleep faulting in page 174 */ 175 work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT); 176 if (!work) 177 return 0; 178 179 work->wakeup_all = false; 180 work->vcpu = vcpu; 181 work->gva = gva; 182 work->addr = hva; 183 work->arch = *arch; 184 work->mm = current->mm; 185 atomic_inc(&work->mm->mm_users); 186 kvm_get_kvm(work->vcpu->kvm); 187 188 /* this can't really happen otherwise gfn_to_pfn_async 189 would succeed */ 190 if (unlikely(kvm_is_error_hva(work->addr))) 191 goto retry_sync; 192 193 INIT_WORK(&work->work, async_pf_execute); 194 if (!schedule_work(&work->work)) 195 goto retry_sync; 196 197 list_add_tail(&work->queue, &vcpu->async_pf.queue); 198 vcpu->async_pf.queued++; 199 kvm_arch_async_page_not_present(vcpu, work); 200 return 1; 201 retry_sync: 202 kvm_put_kvm(work->vcpu->kvm); 203 mmput(work->mm); 204 kmem_cache_free(async_pf_cache, work); 205 return 0; 206 } 207 208 int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu) 209 { 210 struct kvm_async_pf *work; 211 212 if (!list_empty_careful(&vcpu->async_pf.done)) 213 return 0; 214 215 work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC); 216 if (!work) 217 return -ENOMEM; 218 219 work->wakeup_all = true; 220 INIT_LIST_HEAD(&work->queue); /* for list_del to work */ 221 222 spin_lock(&vcpu->async_pf.lock); 223 list_add_tail(&work->link, &vcpu->async_pf.done); 224 spin_unlock(&vcpu->async_pf.lock); 225 226 vcpu->async_pf.queued++; 227 return 0; 228 } 229