Re: [PATCH net-next] virtio_net: add ethtool support for set and get of settings

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Feb 02, 2016 at 01:51:20PM +0100, Nikolay Aleksandrov wrote:
> From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
> 
> This patch allows the user to set and retrieve speed and duplex of the
> virtio_net device via ethtool. Having this functionality is very helpful
> for simulating different environments and also enables the virtio_net
> device to participate in operations where proper speed and duplex are
> required (e.g. currently bonding lacp mode requires full duplex). Custom
> speed and duplex are not allowed, the user-supplied settings are validated
> before applying. Only full and unknown duplex are allowed to be set.

Why isn't half duplex legal?

> 
> Example:
> $ ethtool eth1
> Settings for eth1:
> ...
> 	Speed: Unknown!
> 	Duplex: Unknown! (255)
> $ ethtool -s eth1 speed 1000 duplex full
> $ ethtool eth1
> Settings for eth1:
> ...
> 	Speed: 1000Mb/s
> 	Duplex: Full
> 
> Based on a patch by Roopa Prabhu.
> 
> CC: Roopa Prabhu <roopa@cumulusnetworks.com>
> CC: Michael S. Tsirkin <mst@redhat.com>
> CC: virtualization@lists.linux-foundation.org
> Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>

Thanks!
Looks ok with one comment, see below.

> ---
> Allowed to set unknown speed/duplex if the user wants to reset them, though
> the user-space ethtool tool currently doesn't allow setting them.
> 
>  drivers/net/virtio_net.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 74 insertions(+)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 767ab11a6e9f..722ade567ee5 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -146,6 +146,10 @@ struct virtnet_info {
>  	virtio_net_ctrl_ack ctrl_status;
>  	u8 ctrl_promisc;
>  	u8 ctrl_allmulti;
> +
> +	/* Ethtool settings */
> +	u8 duplex;
> +	u32 speed;
>  };
>  
>  struct padded_vnet_hdr {
> @@ -1376,6 +1380,72 @@ static void virtnet_get_channels(struct net_device *dev,
>  	channels->other_count = 0;
>  }
>  
> +static bool virtnet_validate_speed(u32 speed)
> +{
> +	switch (speed) {
> +	case SPEED_10:
> +	case SPEED_100:
> +	case SPEED_1000:
> +	case SPEED_2500:
> +	case SPEED_5000:
> +	case SPEED_10000:
> +	case SPEED_20000:
> +	case SPEED_25000:
> +	case SPEED_40000:
> +	case SPEED_50000:
> +	case SPEED_56000:
> +	case SPEED_100000:
> +	case SPEED_UNKNOWN:
> +		return true;
> +	}
> +
> +	return false;
> +}
> +
> +static bool virtnet_validate_duplex(u8 duplex)
> +{
> +	switch (duplex) {
> +	case DUPLEX_FULL:
> +	case DUPLEX_UNKNOWN:
> +		return true;
> +	}
> +
> +	return false;
> +}

Let's put the validating functions near where the
enums are defined so people remember to extend these
when adding new speeds?
Will help e.g. tun reuse this, too.

> +
> +static int virtnet_set_settings(struct net_device *dev, struct ethtool_cmd *cmd)
> +{
> +	struct virtnet_info *vi = netdev_priv(dev);
> +	u32 speed = ethtool_cmd_speed(cmd);
> +
> +	/* don't allow custom speed and duplex */
> +	if (!virtnet_validate_speed(speed) ||
> +	    !virtnet_validate_duplex(cmd->duplex))
> +		return -EINVAL;
> +	vi->speed = speed;
> +	vi->duplex = cmd->duplex;
> +
> +	return 0;
> +}
> +
> +static int virtnet_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
> +{
> +	struct virtnet_info *vi = netdev_priv(dev);
> +
> +	ethtool_cmd_speed_set(cmd, vi->speed);
> +	cmd->duplex = vi->duplex;
> +
> +	return 0;
> +}
> +
> +static void virtnet_init_settings(struct net_device *dev)
> +{
> +	struct virtnet_info *vi = netdev_priv(dev);
> +
> +	vi->speed = SPEED_UNKNOWN;
> +	vi->duplex = DUPLEX_UNKNOWN;
> +}
> +
>  static const struct ethtool_ops virtnet_ethtool_ops = {
>  	.get_drvinfo = virtnet_get_drvinfo,
>  	.get_link = ethtool_op_get_link,
> @@ -1383,6 +1453,8 @@ static const struct ethtool_ops virtnet_ethtool_ops = {
>  	.set_channels = virtnet_set_channels,
>  	.get_channels = virtnet_get_channels,
>  	.get_ts_info = ethtool_op_get_ts_info,
> +	.get_settings = virtnet_get_settings,
> +	.set_settings = virtnet_set_settings,
>  };
>  
>  #define MIN_MTU 68
> @@ -1855,6 +1927,8 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	netif_set_real_num_tx_queues(dev, vi->curr_queue_pairs);
>  	netif_set_real_num_rx_queues(dev, vi->curr_queue_pairs);
>  
> +	virtnet_init_settings(dev);
> +
>  	err = register_netdev(dev);
>  	if (err) {
>  		pr_debug("virtio_net: registering device failed\n");
> -- 
> 2.4.3