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 page *page = NULL; 60 struct kvm_async_pf *apf = 61 container_of(work, struct kvm_async_pf, work); 62 struct mm_struct *mm = apf->mm; 63 struct kvm_vcpu *vcpu = apf->vcpu; 64 unsigned long addr = apf->addr; 65 gva_t gva = apf->gva; 66 67 might_sleep(); 68 69 use_mm(mm); 70 down_read(&mm->mmap_sem); 71 get_user_pages(current, mm, addr, 1, 1, 0, &page, NULL); 72 up_read(&mm->mmap_sem); 73 unuse_mm(mm); 74 75 spin_lock(&vcpu->async_pf.lock); 76 list_add_tail(&apf->link, &vcpu->async_pf.done); 77 apf->page = page; 78 apf->done = true; 79 spin_unlock(&vcpu->async_pf.lock); 80 81 /* 82 * apf may be freed by kvm_check_async_pf_completion() after 83 * this point 84 */ 85 86 trace_kvm_async_pf_completed(addr, page, gva); 87 88 if (waitqueue_active(&vcpu->wq)) 89 wake_up_interruptible(&vcpu->wq); 90 91 mmdrop(mm); 92 kvm_put_kvm(vcpu->kvm); 93 } 94 95 void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu) 96 { 97 /* cancel outstanding work queue item */ 98 while (!list_empty(&vcpu->async_pf.queue)) { 99 struct kvm_async_pf *work = 100 list_entry(vcpu->async_pf.queue.next, 101 typeof(*work), queue); 102 cancel_work_sync(&work->work); 103 list_del(&work->queue); 104 if (!work->done) /* work was canceled */ 105 kmem_cache_free(async_pf_cache, work); 106 } 107 108 spin_lock(&vcpu->async_pf.lock); 109 while (!list_empty(&vcpu->async_pf.done)) { 110 struct kvm_async_pf *work = 111 list_entry(vcpu->async_pf.done.next, 112 typeof(*work), link); 113 list_del(&work->link); 114 if (work->page) 115 put_page(work->page); 116 kmem_cache_free(async_pf_cache, work); 117 } 118 spin_unlock(&vcpu->async_pf.lock); 119 120 vcpu->async_pf.queued = 0; 121 } 122 123 void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu) 124 { 125 struct kvm_async_pf *work; 126 127 while (!list_empty_careful(&vcpu->async_pf.done) && 128 kvm_arch_can_inject_async_page_present(vcpu)) { 129 spin_lock(&vcpu->async_pf.lock); 130 work = list_first_entry(&vcpu->async_pf.done, typeof(*work), 131 link); 132 list_del(&work->link); 133 spin_unlock(&vcpu->async_pf.lock); 134 135 if (work->page) 136 kvm_arch_async_page_ready(vcpu, work); 137 kvm_arch_async_page_present(vcpu, work); 138 139 list_del(&work->queue); 140 vcpu->async_pf.queued--; 141 if (work->page) 142 put_page(work->page); 143 kmem_cache_free(async_pf_cache, work); 144 } 145 } 146 147 int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn, 148 struct kvm_arch_async_pf *arch) 149 { 150 struct kvm_async_pf *work; 151 152 if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU) 153 return 0; 154 155 /* setup delayed work */ 156 157 /* 158 * do alloc nowait since if we are going to sleep anyway we 159 * may as well sleep faulting in page 160 */ 161 work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT); 162 if (!work) 163 return 0; 164 165 work->page = NULL; 166 work->done = false; 167 work->vcpu = vcpu; 168 work->gva = gva; 169 work->addr = gfn_to_hva(vcpu->kvm, gfn); 170 work->arch = *arch; 171 work->mm = current->mm; 172 atomic_inc(&work->mm->mm_count); 173 kvm_get_kvm(work->vcpu->kvm); 174 175 /* this can't really happen otherwise gfn_to_pfn_async 176 would succeed */ 177 if (unlikely(kvm_is_error_hva(work->addr))) 178 goto retry_sync; 179 180 INIT_WORK(&work->work, async_pf_execute); 181 if (!schedule_work(&work->work)) 182 goto retry_sync; 183 184 list_add_tail(&work->queue, &vcpu->async_pf.queue); 185 vcpu->async_pf.queued++; 186 kvm_arch_async_page_not_present(vcpu, work); 187 return 1; 188 retry_sync: 189 kvm_put_kvm(work->vcpu->kvm); 190 mmdrop(work->mm); 191 kmem_cache_free(async_pf_cache, work); 192 return 0; 193 } 194 195 int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu) 196 { 197 struct kvm_async_pf *work; 198 199 if (!list_empty_careful(&vcpu->async_pf.done)) 200 return 0; 201 202 work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC); 203 if (!work) 204 return -ENOMEM; 205 206 work->page = bad_page; 207 get_page(bad_page); 208 INIT_LIST_HEAD(&work->queue); /* for list_del to work */ 209 210 spin_lock(&vcpu->async_pf.lock); 211 list_add_tail(&work->link, &vcpu->async_pf.done); 212 spin_unlock(&vcpu->async_pf.lock); 213 214 vcpu->async_pf.queued++; 215 return 0; 216 } 217