If negociated, 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 <[email protected]> Cc: Aaron Conole <[email protected] Signed-off-by: Maxime Coquelin <[email protected]> --- hw/net/virtio-net.c | 16 ++++++++++++++++ include/hw/virtio/virtio-net.h | 1 + 2 files changed, 17 insertions(+) diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 01f1351..0974d87 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -50,6 +50,8 @@ 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)}, {} }; @@ -74,6 +76,10 @@ static void virtio_net_get_config(VirtIODevice *vdev, uint8_t *config) VirtIONet *n = VIRTIO_NET(vdev); struct virtio_net_config netcfg; + if (virtio_vdev_has_feature(vdev, VIRTIO_NET_F_MTU)) { + virtio_stw_p(vdev, &netcfg.mtu, n->mtu); + } + virtio_stw_p(vdev, &netcfg.status, n->status); virtio_stw_p(vdev, &netcfg.max_virtqueue_pairs, n->max_queues); memcpy(netcfg.mac, n->mac, ETH_ALEN); @@ -526,6 +532,7 @@ static uint64_t virtio_net_get_features(VirtIODevice *vdev, uint64_t features, features |= n->host_features; virtio_add_feature(&features, VIRTIO_NET_F_MAC); + virtio_add_feature(&features, VIRTIO_NET_F_MTU); if (!peer_has_vnet_hdr(n)) { virtio_clear_feature(&features, VIRTIO_NET_F_CSUM); @@ -627,6 +634,14 @@ 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)); + } + } } static int virtio_net_handle_rx_mode(VirtIONet *n, uint8_t cmd, @@ -1688,6 +1703,7 @@ 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); diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h index 91ed97c..13b2a8d 100644 --- a/include/hw/virtio/virtio-net.h +++ b/include/hw/virtio/virtio-net.h @@ -95,6 +95,7 @@ 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
