From nobody Tue Feb 10 08:27:51 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1512153216457855.8123846883459; Fri, 1 Dec 2017 10:33:36 -0800 (PST) Received: from localhost ([::1]:59528 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eKq7s-0003Jy-Jw for importer@patchew.org; Fri, 01 Dec 2017 13:33:28 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54782) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eKonx-0000ns-Fz for qemu-devel@nongnu.org; Fri, 01 Dec 2017 12:08:50 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eKonw-000758-Kz for qemu-devel@nongnu.org; Fri, 01 Dec 2017 12:08:49 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58568) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eKonw-00074m-E3; Fri, 01 Dec 2017 12:08:48 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A5FCC356D0; Fri, 1 Dec 2017 17:08:47 +0000 (UTC) Received: from redhat.com (ovpn-120-78.rdu2.redhat.com [10.10.120.78]) by smtp.corp.redhat.com (Postfix) with SMTP id B1AFD6A024; Fri, 1 Dec 2017 17:08:46 +0000 (UTC) Date: Fri, 1 Dec 2017 19:08:46 +0200 From: "Michael S. Tsirkin" To: qemu-devel@nongnu.org Message-ID: <1512148088-28733-4-git-send-email-mst@redhat.com> References: <1512148088-28733-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1512148088-28733-1-git-send-email-mst@redhat.com> X-Mutt-Fcc: =sent X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Fri, 01 Dec 2017 17:08:47 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 3/7] vhost: restore avail index from vring used index on disconnection 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: Peter Maydell , Maxime Coquelin , qemu-stable@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Maxime Coquelin vhost_virtqueue_stop() gets avail index value from the backend, except if the backend is not responding. It happens when the backend crashes, and in this case, internal state of the virtio queue is inconsistent, making packets to corrupt the vring state. With a Linux guest, it results in following error message on backend reconnection: [ 22.444905] virtio_net virtio0: output.0:id 0 is not a head! [ 22.446746] net enp0s3: Unexpected TXQ (0) queue failure: -5 [ 22.476360] net enp0s3: Unexpected TXQ (0) queue failure: -5 Fixes: 283e2c2adcb8 ("net: virtio-net discards TX data after link down") Cc: qemu-stable@nongnu.org Signed-off-by: Maxime Coquelin Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/virtio/vhost.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index ddc42f0..5404194 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -1138,6 +1138,10 @@ static void vhost_virtqueue_stop(struct vhost_dev *d= ev, r =3D dev->vhost_ops->vhost_get_vring_base(dev, &state); if (r < 0) { VHOST_OPS_DEBUG("vhost VQ %d ring restore failed: %d", idx, r); + /* Connection to the backend is broken, so let's sync internal + * last avail idx to the device used idx. + */ + virtio_queue_restore_last_avail_idx(vdev, idx); } else { virtio_queue_set_last_avail_idx(vdev, idx, state.num); } --=20 MST