From patchwork Mon Jan 30 10:09:36 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Halil Pasic X-Patchwork-Id: 9544661 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 0E07260417 for ; Mon, 30 Jan 2017 10:12:04 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EF58326C2F for ; Mon, 30 Jan 2017 10:12:03 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E3BE32811D; Mon, 30 Jan 2017 10:12:03 +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 vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6CD1E26C2F for ; Mon, 30 Jan 2017 10:12:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751274AbdA3KLW (ORCPT ); Mon, 30 Jan 2017 05:11:22 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:48031 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751198AbdA3KJw (ORCPT ); Mon, 30 Jan 2017 05:09:52 -0500 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v0UA9BUQ017427 for ; Mon, 30 Jan 2017 05:09:46 -0500 Received: from e06smtp08.uk.ibm.com (e06smtp08.uk.ibm.com [195.75.94.104]) by mx0a-001b2d01.pphosted.com with ESMTP id 2890j94rn3-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 30 Jan 2017 05:09:46 -0500 Received: from localhost by e06smtp08.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Tsirkin" , Jason Wang Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, Cornelia Huck , Greg Kurz , "Michael A. Tebolt" , "Dr. David Alan Gilbert" , Halil Pasic Subject: [PATCH] vhost: fix initialization for vq->is_le Date: Mon, 30 Jan 2017 11:09:36 +0100 X-Mailer: git-send-email 2.8.4 X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17013010-0032-0000-0000-000007132DD6 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17013010-0033-0000-0000-0000233F0444 Message-Id: <20170130100936.17065-1-pasic@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-01-30_07:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000 definitions=main-1701300106 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently, under certain circumstances vhost_init_is_le does just a part of the initialization job, and depends on vhost_reset_is_le being called too. For this reason vhost_vq_init_access used to call vhost_reset_is_le when vq->private_data is NULL. This is not only counter intuitive, but also real a problem because it breaks vhost_net. The bug was introduced to vhost_net with commit 2751c9882b94 ("vhost: cross-endian support for legacy devices"). The symptom is corruption of the vq's used.idx field (virtio) after VHOST_NET_SET_BACKEND was issued as a part of the vhost shutdown on a vq with pending descriptors. Let us make sure the outcome of vhost_init_is_le never depend on the state it is actually supposed to initialize, and fix virtio_net by removing the reset from vhost_vq_init_access. With the above, there is no reason for vhost_reset_is_le to do just half of the job. Let us make vhost_reset_is_le reinitialize is_le. Signed-off-by: Halil Pasic Reported-by: Michael A. Tebolt Reported-by: Dr. David Alan Gilbert Fixes: commit 2751c9882b94 ("vhost: cross-endian support for legacy devices") Reviewed-by: Greg Kurz Tested-by: Michael A. Tebolt Acked-by: Jason Wang --- The bug was already discussed here: http://www.spinics.net/lists/kvm/msg144365.html This is a follow up patch. --- drivers/vhost/vhost.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index d643260..8f99fe0 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -130,14 +130,14 @@ static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx, static void vhost_init_is_le(struct vhost_virtqueue *vq) { - if (vhost_has_feature(vq, VIRTIO_F_VERSION_1)) - vq->is_le = true; + vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) + || virtio_legacy_is_little_endian(); } #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */ static void vhost_reset_is_le(struct vhost_virtqueue *vq) { - vq->is_le = virtio_legacy_is_little_endian(); + vhost_init_is_le(vq); } struct vhost_flush_struct { @@ -1714,10 +1714,8 @@ int vhost_vq_init_access(struct vhost_virtqueue *vq) int r; bool is_le = vq->is_le; - if (!vq->private_data) { - vhost_reset_is_le(vq); + if (!vq->private_data) return 0; - } vhost_init_is_le(vq);