From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44976) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c7VKW-0002iP-EG for qemu-devel@nongnu.org; Thu, 17 Nov 2016 17:38:53 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c7VKT-0006XZ-9Q for qemu-devel@nongnu.org; Thu, 17 Nov 2016 17:38:52 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34726) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1c7VKT-0006XH-1c for qemu-devel@nongnu.org; Thu, 17 Nov 2016 17:38:49 -0500 Date: Fri, 18 Nov 2016 00:38:47 +0200 From: "Michael S. Tsirkin" Message-ID: <20161118003558-mutt-send-email-mst@kernel.org> References: <1479419887-10515-1-git-send-email-maxime.coquelin@redhat.com> <1479419887-10515-4-git-send-email-maxime.coquelin@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1479419887-10515-4-git-send-email-maxime.coquelin@redhat.com> Subject: Re: [Qemu-devel] [RFC v2 3/3] virtio-net: Add MTU feature support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Maxime Coquelin Cc: aconole@redhat.com, pbonzini@redhat.com, qemu-devel@nongnu.org, jasowang@redhat.com, yuanhan.liu@linux.intel.com On Thu, Nov 17, 2016 at 10:58:07PM +0100, Maxime Coquelin wrote: > If negotiated, virtio-net gets the advised MTU from vhost-net, > and provides it to the guest through a new virtio_net_config > entry. > > Cc: Michael S. Tsirkin > Cc: Aaron Conole Signed-off-by: Maxime Coquelin > --- > hw/net/virtio-net.c | 14 ++++++++++++++ > include/hw/virtio/virtio-net.h | 1 + > 2 files changed, 15 insertions(+) > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c > index 5009533..36843fe 100644 > --- a/hw/net/virtio-net.c > +++ b/hw/net/virtio-net.c > @@ -55,6 +55,8 @@ static VirtIOFeature feature_sizes[] = { > .end = endof(struct virtio_net_config, status)}, > {.flags = 1 << VIRTIO_NET_F_MQ, > .end = endof(struct virtio_net_config, max_virtqueue_pairs)}, > + {.flags = 1 << VIRTIO_NET_F_MTU, > + .end = endof(struct virtio_net_config, mtu)}, > {} > }; > > @@ -81,6 +83,7 @@ static void virtio_net_get_config(VirtIODevice *vdev, uint8_t *config) > > virtio_stw_p(vdev, &netcfg.status, n->status); > virtio_stw_p(vdev, &netcfg.max_virtqueue_pairs, n->max_queues); > + virtio_stw_p(vdev, &netcfg.mtu, n->mtu); > memcpy(netcfg.mac, n->mac, ETH_ALEN); > memcpy(config, &netcfg, n->config_size); > } > @@ -636,6 +639,14 @@ static void virtio_net_set_features(VirtIODevice *vdev, uint64_t features) > } else { > memset(n->vlans, 0xff, MAX_VLAN >> 3); > } > + > + if (virtio_has_feature(features, VIRTIO_NET_F_MTU)) { > + NetClientState *nc = qemu_get_queue(n->nic); > + > + if (get_vhost_net(nc->peer)) { > + n->mtu = vhost_net_get_mtu(get_vhost_net(nc->peer)); This means migration breaks silently if you move from a bigger to smaller mtu. We don't necessarily have to make it work, but it should be detected and reported. > + } > + } > } > > static int virtio_net_handle_rx_mode(VirtIONet *n, uint8_t cmd, What about non-vhost traffic? You need to ensure guest does not get bigger packets. > @@ -1695,6 +1706,7 @@ static void virtio_net_set_config_size(VirtIONet *n, uint64_t host_features) > { > int i, config_size = 0; > virtio_add_feature(&host_features, VIRTIO_NET_F_MAC); > + virtio_add_feature(&host_features, VIRTIO_NET_F_MTU); > for (i = 0; feature_sizes[i].flags != 0; i++) { > if (host_features & feature_sizes[i].flags) { > config_size = MAX(feature_sizes[i].end, config_size); > @@ -1922,6 +1934,8 @@ static Property virtio_net_properties[] = { > DEFINE_PROP_STRING("tx", VirtIONet, net_conf.tx), > DEFINE_PROP_UINT16("rx_queue_size", VirtIONet, net_conf.rx_queue_size, > VIRTIO_NET_RX_QUEUE_DEFAULT_SIZE), > + DEFINE_PROP_BIT("host_mtu", VirtIONet, host_features, > + VIRTIO_NET_F_MTU, true), > DEFINE_PROP_END_OF_LIST(), > }; > Cross version migration support is missing here. > diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h > index 0ced975..b6394c8 100644 > --- a/include/hw/virtio/virtio-net.h > +++ b/include/hw/virtio/virtio-net.h > @@ -96,6 +96,7 @@ typedef struct VirtIONet { > QEMUTimer *announce_timer; > int announce_counter; > bool needs_vnet_hdr_swap; > + uint16_t mtu; > } VirtIONet; > > void virtio_net_set_netclient_name(VirtIONet *n, const char *name, > -- > 2.7.4