From patchwork Tue Mar 29 16:12:55 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 8688851 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 972E09F36E for ; Tue, 29 Mar 2016 16:16:50 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id DDD882034E for ; Tue, 29 Mar 2016 16:16:49 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B89B02034C for ; Tue, 29 Mar 2016 16:16:48 +0000 (UTC) Received: from localhost ([::1]:48555 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1akwK0-0008Sa-3I for patchwork-qemu-devel@patchwork.kernel.org; Tue, 29 Mar 2016 12:16:48 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34812) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1akwGY-00027d-IE for qemu-devel@nongnu.org; Tue, 29 Mar 2016 12:13:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1akwGU-000236-2w for qemu-devel@nongnu.org; Tue, 29 Mar 2016 12:13:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48472) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1akwGT-00022h-PX for qemu-devel@nongnu.org; Tue, 29 Mar 2016 12:13:09 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (Postfix) with ESMTPS id 7D94073036; Tue, 29 Mar 2016 16:13:09 +0000 (UTC) Received: from localhost (ovpn-112-65.ams2.redhat.com [10.36.112.65]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u2TGD8QJ008200; Tue, 29 Mar 2016 12:13:08 -0400 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Date: Tue, 29 Mar 2016 17:12:55 +0100 Message-Id: <1459267981-23408-4-git-send-email-stefanha@redhat.com> In-Reply-To: <1459267981-23408-1-git-send-email-stefanha@redhat.com> References: <1459267981-23408-1-git-send-email-stefanha@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 29 Mar 2016 16:13:09 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Cc: Cornelia Huck , Fam Zheng , Stefan Hajnoczi , "Michael S. Tsirkin" Subject: [Qemu-devel] [RFC v2 3/9] virtio: stop virtqueue processing if device is broken X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP QEMU prints an error message and exits when the device enters an invalid state. Terminating the process is heavy-handed. The guest may still be able to function even if there is a bug in a virtio guest driver. Moreover, exiting is a bug in nested virtualization where a nested guest could DoS other nested guests by killing a pass-through virtio device. I don't think this configuration is possible today but it is likely in the future. If the broken flag is set, do not process virtqueues or write back used descriptors. The broken flag can be cleared again by resetting the device. Signed-off-by: Stefan Hajnoczi --- hw/virtio/virtio.c | 39 +++++++++++++++++++++++++++++++++++++++ include/hw/virtio/virtio.h | 3 +++ 2 files changed, 42 insertions(+) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index de8a3b3..ff2c736 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -276,6 +276,10 @@ void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem, virtqueue_unmap_sg(vq, elem, len); + if (unlikely(vq->vdev->broken)) { + return; + } + idx = (idx + vq->used_idx) % vq->vring.num; uelem.id = elem->index; @@ -286,6 +290,12 @@ void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem, void virtqueue_flush(VirtQueue *vq, unsigned int count) { uint16_t old, new; + + if (unlikely(vq->vdev->broken)) { + vq->inuse -= count; + return; + } + /* Make sure buffer is written before we update index. */ smp_wmb(); trace_virtqueue_flush(vq, count); @@ -546,6 +556,9 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz) struct iovec iov[VIRTQUEUE_MAX_SIZE]; VRingDesc desc; + if (unlikely(vdev->broken)) { + return NULL; + } if (virtio_queue_empty(vq)) { return NULL; } @@ -705,6 +718,10 @@ static void virtio_notify_vector(VirtIODevice *vdev, uint16_t vector) BusState *qbus = qdev_get_parent_bus(DEVICE(vdev)); VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus); + if (unlikely(vdev->broken)) { + return; + } + if (k->notify) { k->notify(qbus->parent, vector); } @@ -788,6 +805,7 @@ void virtio_reset(void *opaque) k->reset(vdev); } + vdev->broken = false; vdev->guest_features = 0; vdev->queue_sel = 0; vdev->status = 0; @@ -1091,6 +1109,10 @@ void virtio_queue_notify_vq(VirtQueue *vq) if (vq->vring.desc && vq->handle_output) { VirtIODevice *vdev = vq->vdev; + if (unlikely(vdev->broken)) { + return; + } + trace_virtio_queue_notify(vdev, vq - vdev->vq, vq); vq->handle_output(vdev, vq); } @@ -1661,6 +1683,7 @@ void virtio_init(VirtIODevice *vdev, const char *name, vdev->config_vector = VIRTIO_NO_VECTOR; vdev->vq = g_malloc0(sizeof(VirtQueue) * VIRTIO_QUEUE_MAX); vdev->vm_running = runstate_is_running(); + vdev->broken = false; for (i = 0; i < VIRTIO_QUEUE_MAX; i++) { vdev->vq[i].vector = VIRTIO_NO_VECTOR; vdev->vq[i].vdev = vdev; @@ -1829,6 +1852,22 @@ void virtio_device_set_child_bus_name(VirtIODevice *vdev, char *bus_name) vdev->bus_name = g_strdup(bus_name); } +void GCC_FMT_ATTR(2, 3) virtio_error(VirtIODevice *vdev, const char *fmt, ...) +{ + va_list ap; + + va_start(ap, fmt); + error_vreport(fmt, ap); + va_end(ap); + + vdev->broken = true; + + if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) { + vdev->status |= VIRTIO_CONFIG_S_NEEDS_RESET; + virtio_notify_config(vdev); + } +} + static void virtio_device_realize(DeviceState *dev, Error **errp) { VirtIODevice *vdev = VIRTIO_DEVICE(dev); diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h index 2b5b248..1565e53 100644 --- a/include/hw/virtio/virtio.h +++ b/include/hw/virtio/virtio.h @@ -87,6 +87,7 @@ struct VirtIODevice VirtQueue *vq; uint16_t device_id; bool vm_running; + bool broken; /* device in invalid state, needs reset */ VMChangeStateEntry *vmstate; char *bus_name; uint8_t device_endian; @@ -135,6 +136,8 @@ void virtio_init(VirtIODevice *vdev, const char *name, uint16_t device_id, size_t config_size); void virtio_cleanup(VirtIODevice *vdev); +void virtio_error(VirtIODevice *vdev, const char *fmt, ...) GCC_FMT_ATTR(2, 3); + /* Set the child bus name. */ void virtio_device_set_child_bus_name(VirtIODevice *vdev, char *bus_name);