virtio-net: Add initial MTU advice feature
This commit adds the feature bit and associated mtu device entry for the
virtio network device. When a virtio device comes up, it checks the
feature bit for the VIRTIO_NET_F_MTU feature. If such feature bit is
enabled, the driver will read the advised MTU and use it as the initial
value.
Signed-off-by: Aaron Conole <aconole@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index e0638e5..192f321 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1780,6 +1780,7 @@
struct net_device *dev;
struct virtnet_info *vi;
u16 max_queue_pairs;
+ int mtu;
if (!vdev->config->get) {
dev_err(&vdev->dev, "%s failure: config access disabled\n",
@@ -1896,6 +1897,14 @@
if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
vi->has_cvq = true;
+ if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
+ mtu = virtio_cread16(vdev,
+ offsetof(struct virtio_net_config,
+ mtu));
+ if (virtnet_change_mtu(dev, mtu))
+ __virtio_clear_bit(vdev, VIRTIO_NET_F_MTU);
+ }
+
if (vi->any_header_sg)
dev->needed_headroom = vi->hdr_len;
@@ -2067,6 +2076,7 @@
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 = {