From patchwork Tue Apr 12 13:25:27 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 8810331 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 7F7E2C0553 for ; Tue, 12 Apr 2016 13:26:11 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id C28DC2035D for ; Tue, 12 Apr 2016 13:26:10 +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 EAAD420357 for ; Tue, 12 Apr 2016 13:26:08 +0000 (UTC) Received: from localhost ([::1]:49493 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1apyKW-0002gh-8g for patchwork-qemu-devel@patchwork.kernel.org; Tue, 12 Apr 2016 09:26:08 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44951) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1apyKB-0002Ur-53 for qemu-devel@nongnu.org; Tue, 12 Apr 2016 09:25:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1apyKA-0005UF-1w for qemu-devel@nongnu.org; Tue, 12 Apr 2016 09:25:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39782) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1apyK9-0005UA-Qk for qemu-devel@nongnu.org; Tue, 12 Apr 2016 09:25:45 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (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 754F36406A; Tue, 12 Apr 2016 13:25:45 +0000 (UTC) Received: from localhost (ovpn-112-60.ams2.redhat.com [10.36.112.60]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u3CDPgdH015958; Tue, 12 Apr 2016 09:25:43 -0400 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Date: Tue, 12 Apr 2016 14:25:27 +0100 Message-Id: <1460467534-29147-4-git-send-email-stefanha@redhat.com> In-Reply-To: <1460467534-29147-1-git-send-email-stefanha@redhat.com> References: <1460467534-29147-1-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 [10.5.110.38]); Tue, 12 Apr 2016 13:25:45 +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 v3 03/10] 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-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 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 02c71a2..cedda4b 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -279,6 +279,10 @@ 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; @@ -289,6 +293,12 @@ 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); @@ -549,6 +559,9 @@ 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; } @@ -708,6 +721,10 @@ 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); } @@ -791,6 +808,7 @@ void virtio_reset(void *opaque) k->reset(vdev); } + vdev->broken = false; vdev->guest_features = 0; vdev->queue_sel = 0; vdev->status = 0; @@ -1104,6 +1122,10 @@ 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); } @@ -1675,6 +1697,7 @@ 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; @@ -1852,6 +1875,22 @@ 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 6a37065..012b0d1 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);