hv_netvsc: add ethtool support for set and get of settings

This patch allows the user to set and retrieve speed and duplex of the
hv_netvsc device via ethtool.

Example:
$ ethtool eth0
Settings for eth0:
...
    Speed: Unknown!
    Duplex: Unknown! (255)
...
$ ethtool -s eth0 speed 1000 duplex full
$ ethtool eth0
Settings for eth0:
...
    Speed: 1000Mb/s
    Duplex: Full
...

This is based on patches by Roopa Prabhu and Nikolay Aleksandrov.
Signed-off-by: Simon Xiao <sixiao@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/hyperv/hyperv_net.h

@@ -658,6 +658,10 @@ struct net_device_context {
 
 	struct netvsc_stats __percpu *tx_stats;
 	struct netvsc_stats __percpu *rx_stats;
+
+	/* Ethtool settings */
+	u8 duplex;
+	u32 speed;
 };
 
 /* Per netvsc device */

drivers/net/hyperv/netvsc_drv.c

@@ -799,6 +799,58 @@ static int netvsc_set_channels(struct net_device *net,
 	goto do_set;
 }
 
+static bool netvsc_validate_ethtool_ss_cmd(const struct ethtool_cmd *cmd)
+{
+	struct ethtool_cmd diff1 = *cmd;
+	struct ethtool_cmd diff2 = {};
+
+	ethtool_cmd_speed_set(&diff1, 0);
+	diff1.duplex = 0;
+	/* advertising and cmd are usually set */
+	diff1.advertising = 0;
+	diff1.cmd = 0;
+	/* We set port to PORT_OTHER */
+	diff2.port = PORT_OTHER;
+
+	return !memcmp(&diff1, &diff2, sizeof(diff1));
+}
+
+static void netvsc_init_settings(struct net_device *dev)
+{
+	struct net_device_context *ndc = netdev_priv(dev);
+
+	ndc->speed = SPEED_UNKNOWN;
+	ndc->duplex = DUPLEX_UNKNOWN;
+}
+
+static int netvsc_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
+{
+	struct net_device_context *ndc = netdev_priv(dev);
+
+	ethtool_cmd_speed_set(cmd, ndc->speed);
+	cmd->duplex = ndc->duplex;
+	cmd->port = PORT_OTHER;
+
+	return 0;
+}
+
+static int netvsc_set_settings(struct net_device *dev, struct ethtool_cmd *cmd)
+{
+	struct net_device_context *ndc = netdev_priv(dev);
+	u32 speed;
+
+	speed = ethtool_cmd_speed(cmd);
+	if (!ethtool_validate_speed(speed) ||
+	    !ethtool_validate_duplex(cmd->duplex) ||
+	    !netvsc_validate_ethtool_ss_cmd(cmd))
+		return -EINVAL;
+
+	ndc->speed = speed;
+	ndc->duplex = cmd->duplex;
+
+	return 0;
+}
+
 static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 {
 	struct net_device_context *ndevctx = netdev_priv(ndev);
@@ -923,6 +975,8 @@ static const struct ethtool_ops ethtool_ops = {
 	.get_channels   = netvsc_get_channels,
 	.set_channels   = netvsc_set_channels,
 	.get_ts_info	= ethtool_op_get_ts_info,
+	.get_settings	= netvsc_get_settings,
+	.set_settings	= netvsc_set_settings,
 };
 
 static const struct net_device_ops device_ops = {
@@ -1115,6 +1169,8 @@ static int netvsc_probe(struct hv_device *dev,
 	netif_set_real_num_tx_queues(net, nvdev->num_chn);
 	netif_set_real_num_rx_queues(net, nvdev->num_chn);
 
+	netvsc_init_settings(net);
+
 	ret = register_netdev(net);
 	if (ret != 0) {
 		pr_err("Unable to register netdev.\n");