diff options
Diffstat (limited to 'virt/kvm/async_pf.c')
| -rw-r--r-- | virt/kvm/async_pf.c | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c new file mode 100644 index 000000000000..857d63431cb7 --- /dev/null +++ b/virt/kvm/async_pf.c @@ -0,0 +1,190 @@ +/* + * 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 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) +{ + if (async_pf_cache) + 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 page *page = NULL; + 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; + + might_sleep(); + + use_mm(mm); + down_read(&mm->mmap_sem); + get_user_pages(current, mm, addr, 1, 1, 0, &page, NULL); + up_read(&mm->mmap_sem); + unuse_mm(mm); + + spin_lock(&vcpu->async_pf.lock); + list_add_tail(&apf->link, &vcpu->async_pf.done); + apf->page = page; + apf->done = true; + 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, page, gva); + + if (waitqueue_active(&vcpu->wq)) + wake_up_interruptible(&vcpu->wq); + + mmdrop(mm); + kvm_put_kvm(vcpu->kvm); +} + +void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu) +{ + /* cancel outstanding work queue item */ + while (!list_empty(&vcpu->async_pf.queue)) { + struct kvm_async_pf *work = + list_entry(vcpu->async_pf.queue.next, + typeof(*work), queue); + cancel_work_sync(&work->work); + list_del(&work->queue); + if (!work->done) /* work was canceled */ + kmem_cache_free(async_pf_cache, work); + } + + spin_lock(&vcpu->async_pf.lock); + while (!list_empty(&vcpu->async_pf.done)) { + struct kvm_async_pf *work = + list_entry(vcpu->async_pf.done.next, + typeof(*work), link); + list_del(&work->link); + if (work->page) + put_page(work->page); + 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; + + if (list_empty_careful(&vcpu->async_pf.done)) + return; + + 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_present(vcpu, work); + + list_del(&work->queue); + vcpu->async_pf.queued--; + if (work->page) + put_page(work->page); + kmem_cache_free(async_pf_cache, work); +} + +int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn, + 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); + if (!work) + return 0; + + work->page = NULL; + work->done = false; + work->vcpu = vcpu; + work->gva = gva; + work->addr = gfn_to_hva(vcpu->kvm, gfn); + work->arch = *arch; + work->mm = current->mm; + atomic_inc(&work->mm->mm_count); + 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); + mmdrop(work->mm); + kmem_cache_free(async_pf_cache, work); + return 0; +} |