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