From patchwork Wed Sep 21 15:52:19 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 9343785 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 4246460B16 for ; Wed, 21 Sep 2016 15:57:33 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1CB0B2A7DC for ; Wed, 21 Sep 2016 15:57:33 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 11C522A7DF; Wed, 21 Sep 2016 15:57:33 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 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.wl.linuxfoundation.org (Postfix) with ESMTPS id 8BB092A7DD for ; Wed, 21 Sep 2016 15:57:32 +0000 (UTC) Received: from localhost ([::1]:43428 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bmjtr-0000bs-NA for patchwork-qemu-devel@patchwork.kernel.org; Wed, 21 Sep 2016 11:57:31 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48104) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bmjp6-0004q9-Ea for qemu-devel@nongnu.org; Wed, 21 Sep 2016 11:52:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bmjp3-0005fM-LN for qemu-devel@nongnu.org; Wed, 21 Sep 2016 11:52:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38062) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bmjp3-0005e1-C8 for qemu-devel@nongnu.org; Wed, 21 Sep 2016 11:52:33 -0400 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CCF9F8E24F; Wed, 21 Sep 2016 15:52:32 +0000 (UTC) Received: from localhost (ovpn-112-31.ams2.redhat.com [10.36.112.31]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u8LFqVI5027039; Wed, 21 Sep 2016 11:52:32 -0400 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Date: Wed, 21 Sep 2016 16:52:19 +0100 Message-Id: <1474473146-19337-3-git-send-email-stefanha@redhat.com> In-Reply-To: <1474473146-19337-1-git-send-email-stefanha@redhat.com> References: <1474473146-19337-1-git-send-email-stefanha@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Wed, 21 Sep 2016 15:52:32 +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 Subject: [Qemu-devel] [PATCH v5 2/9] virtio: stop virtqueue processing if device is broken X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Cornelia Huck , Fam Zheng , Stefan Hajnoczi , "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" 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 Reviewed-by: Cornelia Huck --- 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 1199149..1671ea8 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -303,6 +303,10 @@ 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; @@ -313,6 +317,12 @@ 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); @@ -583,6 +593,9 @@ 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; } @@ -747,6 +760,10 @@ 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); } @@ -830,6 +847,7 @@ void virtio_reset(void *opaque) k->reset(vdev); } + vdev->broken = false; vdev->guest_features = 0; vdev->queue_sel = 0; vdev->status = 0; @@ -1137,6 +1155,10 @@ static 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); } @@ -1758,6 +1780,7 @@ 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; @@ -1944,6 +1967,22 @@ 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)) { + virtio_set_status(vdev, 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 f05559d..888c8de 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);