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

From: "Michael S. Tsirkin" <[email-masked]>
Date: Tue, 2 Feb 2016 16:10:53 +0200

On Tue, Feb 02, 2016 at 02:52:30PM +0100, Nikolay Aleksandrov wrote:
> On 02/02/2016 02:23 PM, Michael S. Tsirkin wrote:
> > On Tue, Feb 02, 2016 at 01:51:20PM +0100, Nikolay Aleksandrov wrote:
> >> From: Nikolay Aleksandrov <[email-masked]>
> >>
> >> 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?
> > 
> 
> It is legal, I'm just not sure it makes sense. Isn't the virtual channel
> always "full duplex" ?

Not if behind it there's a backend that is half duplex.

> At first I had allowed it, but then I decided against and removed it. I
> don't mind adding it back though, the argument against is not strong.
> 
> >>
> >> 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 <[email-masked]>
> >> CC: Michael S. Tsirkin <[email-masked]>
> >> CC: [email-masked]
> >> Signed-off-by: Nikolay Aleksandrov <[email-masked]>
> > 
> > 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.
> > 
> 
> Right, very good suggestion. I'll split this patch in two and will
> add them for everyone to use.
> 
> Thank you,
>  Nik
> 
> >> +
> >> +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