From patchwork Thu Jun 2 15:43:31 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aaron Conole X-Patchwork-Id: 629303 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3rLBRk6C4Bz9t8B for ; Fri, 3 Jun 2016 01:46:58 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161600AbcFBPqx (ORCPT ); Thu, 2 Jun 2016 11:46:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55005 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161825AbcFBPne (ORCPT ); Thu, 2 Jun 2016 11:43:34 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (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 13073C049D5C; Thu, 2 Jun 2016 15:43:34 +0000 (UTC) Received: from aconole-fed23.bos.redhat.com (dhcp-25-45.bos.redhat.com [10.18.25.45]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u52FhV7o001094; Thu, 2 Jun 2016 11:43:33 -0400 From: Aaron Conole To: virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Michael S. Tsirkin" Subject: [PATCH -next 2/2] virtio_net: Read the advised MTU Date: Thu, 2 Jun 2016 11:43:31 -0400 Message-Id: <1464882211-18723-3-git-send-email-aconole@redhat.com> In-Reply-To: <1464882211-18723-1-git-send-email-aconole@redhat.com> References: <1464882211-18723-1-git-send-email-aconole@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Thu, 02 Jun 2016 15:43:34 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This patch checks the feature bit for the VIRTIO_NET_F_MTU feature. If it exists, read the advised MTU and use it. No proper error handling is provided for the case where a user changes the negotiated MTU. A future commit will add proper error handling. Instead, a warning is emitted if the guest changes the device MTU after previously being given advice. Signed-off-by: Aaron Conole --- drivers/net/virtio_net.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index e0638e5..ef5ee01 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1896,6 +1896,12 @@ static int virtnet_probe(struct virtio_device *vdev) if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) vi->has_cvq = true; + if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) { + dev->mtu = virtio_cread16(vdev, + offsetof(struct virtio_net_config, + mtu)); + } + if (vi->any_header_sg) dev->needed_headroom = vi->hdr_len; @@ -2067,6 +2073,7 @@ static unsigned int features[] = { VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, VIRTIO_NET_F_CTRL_MAC_ADDR, VIRTIO_F_ANY_LAYOUT, + VIRTIO_NET_F_MTU, }; static struct virtio_driver virtio_net_driver = {