/* * kvm asynchronous fault support * * Copyright 2010 Red Hat, Inc. * * Author: * Gleb Natapov <gleb@redhat.com> * * This file is free software; you can redistribute it and/or modify * it under the terms of version 2 of the GNU General Public License * as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */ #include <linux/kvm_host.h> #include <linux/slab.h> #include <linux/module.h> #include <linux/mmu_context.h> #include "async_pf.h" #include <trace/events/kvm.h> static inline void kvm_async_page_present_sync(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) { #ifdef CONFIG_KVM_ASYNC_PF_SYNC kvm_arch_async_page_present(vcpu, work); #endif } static inline void kvm_async_page_present_async(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) { #ifndef CONFIG_KVM_ASYNC_PF_SYNC kvm_arch_async_page_present(vcpu, work); #endif } static struct kmem_cache *async_pf_cache; int kvm_async_pf_init(void) { async_pf_cache = KMEM_CACHE(kvm_async_pf, 0); if (!async_pf_cache) return -ENOMEM; return 0; } void kvm_async_pf_deinit(void) { kmem_cache_destroy(async_pf_cache); async_pf_cache = NULL; } void kvm_async_pf_vcpu_init(struct kvm_vcpu *vcpu) { INIT_LIST_HEAD(&vcpu->async_pf.done); INIT_LIST_HEAD(&vcpu->async_pf.queue); spin_lock_init(&vcpu->async_pf.lock); } static void async_pf_execute(struct work_struct *work) { struct kvm_async_pf *apf = container_of(work, struct kvm_async_pf, work); struct mm_struct *mm = apf->mm; struct kvm_vcpu *vcpu = apf->vcpu; unsigned long addr = apf->addr; gva_t gva = apf->gva; int locked = 1; might_sleep(); /* * This work is run asynchromously to the task which owns * mm and might be done in another context, so we must * access remotely. */ down_read(&mm->mmap_sem); get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE, NULL, NULL, &locked); if (locked) up_read(&mm->mmap_sem); kvm_async_page_present_sync(vcpu, apf); spin_lock(&vcpu->async_pf.lock); list_add_tail(&apf->link, &vcpu->async_pf.done); apf->vcpu = NULL; spin_unlock(&vcpu->async_pf.lock); /* * apf may be freed by kvm_check_async_pf_completion() after * this point */ trace_kvm_async_pf_completed(addr, gva); /* * This memory barrier pairs with prepare_to_wait's set_current_state() */ smp_mb(); if (swait_active(&vcpu->wq)) swake_up(&vcpu->wq); mmput(mm); kvm_put_kvm(vcpu->kvm); } void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu) { spin_lock(&vcpu->async_pf.lock); /* cancel outstanding work queue item */ while (!list_empty(&vcpu->async_pf.queue)) { struct kvm_async_pf *work = list_first_entry(&vcpu->async_pf.queue, typeof(*work), queue); list_del(&work->queue); /* * We know it's present in vcpu->async_pf.done, do * nothing here. */ if (!work->vcpu) continue; spin_unlock(&vcpu->async_pf.lock); #ifdef CONFIG_KVM_ASYNC_PF_SYNC flush_work(&work->work); #else if (cancel_work_sync(&work->work)) { mmput(work->mm); kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */ kmem_cache_free(async_pf_cache, work); } #endif spin_lock(&vcpu->async_pf.lock); } while (!list_empty(&vcpu->async_pf.done)) { struct kvm_async_pf *work = list_first_entry(&vcpu->async_pf.done, typeof(*work), link); list_del(&work->link); kmem_cache_free(async_pf_cache, work); } spin_unlock(&vcpu->async_pf.lock); vcpu->async_pf.queued = 0; } void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu) { struct kvm_async_pf *work; while (!list_empty_careful(&vcpu->async_pf.done) && kvm_arch_can_inject_async_page_present(vcpu)) { spin_lock(&vcpu->async_pf.lock); work = list_first_entry(&vcpu->async_pf.done, typeof(*work), link); list_del(&work->link); spin_unlock(&vcpu->async_pf.lock); kvm_arch_async_page_ready(vcpu, work); kvm_async_page_present_async(vcpu, work); list_del(&work->queue); vcpu->async_pf.queued--; kmem_cache_free(async_pf_cache, work); } } int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva, struct kvm_arch_async_pf *arch) { struct kvm_async_pf *work; if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU) return 0; /* setup delayed work */ /* * do alloc nowait since if we are going to sleep anyway we * may as well sleep faulting in page */ work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT | __GFP_NOWARN); if (!work) return 0; work->wakeup_all = false; work->vcpu = vcpu; work->gva = gva; work->addr = hva; work->arch = *arch; work->mm = current->mm; atomic_inc(&work->mm->mm_users); kvm_get_kvm(work->vcpu->kvm); /* this can't really happen otherwise gfn_to_pfn_async would succeed */ if (unlikely(kvm_is_error_hva(work->addr))) goto retry_sync; INIT_WORK(&work->work, async_pf_execute); if (!schedule_work(&work->work)) goto retry_sync; list_add_tail(&work->queue, &vcpu->async_pf.queue); vcpu->async_pf.queued++; kvm_arch_async_page_not_present(vcpu, work); return 1; retry_sync: kvm_put_kvm(work->vcpu->kvm); mmput(work->mm); kmem_cache_free(async_pf_cache, work); return 0; } int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu) { struct kvm_async_pf *work; if (!list_empty_careful(&vcpu->async_pf.done)) return 0; work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC); if (!work) return -ENOMEM; work->wakeup_all = true; INIT_LIST_HEAD(&work->queue); /* for list_del to work */ spin_lock(&vcpu->async_pf.lock); list_add_tail(&work->link, &vcpu->async_pf.done); spin_unlock(&vcpu->async_pf.lock); vcpu->async_pf.queued++; return 0; }