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

[Nikolay Aleksandrov <razor@blackwall.org>]

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.

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>
---
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;
+}
+
+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