On Wed, Dec 19, 2018 at 05:32:27PM -0500, Willem de Bruijn wrote:
> From: Willem de Bruijn <will...@google.com>
>
> Virtio-net devices negotiate LRO support with the host.
> Display the initially negotiated state with ethtool -k.
>
> Also allow configuring it with ethtool -K, reusing the existing
> virtnet_set_guest_offloads helper that disables LRO for XDP.
>
> Virtio-net negotiates TSO4 and TSO6 separately, but ethtool does not
> distinguish between the two. In the unlikely legacy case where the
> host only supports one of the two, maintain the current state.
>
> RTNL is held while calling virtnet_set_features, same as on the path
> from virtnet_xdp_set.
>
> Tested:
> Verified that large-receive-offload is "off [fixed]" when not
> negotiated during initial probe and "on" otherwise.
>
> Measured packet size when scp-ing a large file to the guest with
> nstat (IpExtInOctets / IpInDelivers). Verified that packet size
> exceeds MTU only if ethtool -k shows LRO and/or GRO as enabled.
>
> Signed-off-by: Willem de Bruijn <will...@google.com>
So I see a bug here:
virtnet_send_command calls:
/* Caller should know better */
BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ));
works fine for XDP because that checks VIRTIO_NET_F_CTRL_GUEST_OFFLOADS
in virtnet_xdp_set.
> ---
> drivers/net/virtio_net.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index ea672145f6a66..9890ef30ef32e 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2479,6 +2479,22 @@ static int virtnet_get_phys_port_name(struct
> net_device *dev, char *buf,
> return 0;
> }
>
> +static int virtnet_set_features(struct net_device *dev,
> + netdev_features_t features)
> +{
> + struct virtnet_info *vi = netdev_priv(dev);
> + int ret = 0;
> +
> + if ((dev->features ^ features) & NETIF_F_LRO) {
> + if (features & NETIF_F_LRO)
> + ret = virtnet_restore_guest_offloads(vi);
> + else
> + ret = virtnet_clear_guest_offloads(vi);
> + }
> +
> + return ret;
> +}
> +
> static const struct net_device_ops virtnet_netdev = {
> .ndo_open = virtnet_open,
> .ndo_stop = virtnet_close,
> @@ -2493,6 +2509,7 @@ static const struct net_device_ops virtnet_netdev = {
> .ndo_xdp_xmit = virtnet_xdp_xmit,
> .ndo_features_check = passthru_features_check,
> .ndo_get_phys_port_name = virtnet_get_phys_port_name,
> + .ndo_set_features = virtnet_set_features,
> };
>
> static void virtnet_config_changed_work(struct work_struct *work)
> @@ -2942,6 +2959,11 @@ static int virtnet_probe(struct virtio_device *vdev)
> dev->hw_features |= NETIF_F_TSO6;
> if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_ECN))
> dev->hw_features |= NETIF_F_TSO_ECN;
> + if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) &&
> + virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6)) {
> + dev->hw_features |= NETIF_F_LRO;
> + dev->features |= NETIF_F_LRO;
> + }
>
> dev->features |= NETIF_F_GSO_ROBUST;
>
> --
> 2.20.1.415.g653613c723-goog
