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;
+}