ethtool: Factored out similar ethtool link settings for virtual devices to core

Three virtual devices (ibmveth, virtio_net, and netvsc) all have
similar code to set link settings and validate ethtool command. To
eliminate duplication of code, it is factored out into core/ethtool.c.
Signed-off-by: Cris Forno <cforno12@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/ethtool.h

@@ -420,4 +420,10 @@ struct ethtool_rx_flow_rule *
 ethtool_rx_flow_rule_create(const struct ethtool_rx_flow_spec_input *input);
 void ethtool_rx_flow_rule_destroy(struct ethtool_rx_flow_rule *rule);
 
+bool ethtool_virtdev_validate_cmd(const struct ethtool_link_ksettings *cmd);
+int ethtool_virtdev_set_link_ksettings(struct net_device *dev,
+				       const struct ethtool_link_ksettings *cmd,
+				       u32 *dev_speed, u8 *dev_duplex);
+
+
 #endif /* _LINUX_ETHTOOL_H */

net/ethtool/ioctl.c

@@ -459,6 +459,24 @@ static int load_link_ksettings_from_user(struct ethtool_link_ksettings *to,
 	return 0;
 }
 
+/* Check if the user is trying to change anything besides speed/duplex */
+bool ethtool_virtdev_validate_cmd(const struct ethtool_link_ksettings *cmd)
+{
+	struct ethtool_link_settings base2 = {};
+
+	base2.speed = cmd->base.speed;
+	base2.port = PORT_OTHER;
+	base2.duplex = cmd->base.duplex;
+	base2.cmd = cmd->base.cmd;
+	base2.link_mode_masks_nwords = cmd->base.link_mode_masks_nwords;
+
+	return !memcmp(&base2, &cmd->base, sizeof(base2)) &&
+		bitmap_empty(cmd->link_modes.supported,
+			     __ETHTOOL_LINK_MODE_MASK_NBITS) &&
+		bitmap_empty(cmd->link_modes.lp_advertising,
+			     __ETHTOOL_LINK_MODE_MASK_NBITS);
+}
+
 /* convert a kernel internal ethtool_link_ksettings to
  * ethtool_link_usettings in user space. return 0 on success, errno on
  * error.
@@ -581,6 +599,27 @@ static int ethtool_set_link_ksettings(struct net_device *dev,
 	return err;
 }
 
+int ethtool_virtdev_set_link_ksettings(struct net_device *dev,
+				       const struct ethtool_link_ksettings *cmd,
+				       u32 *dev_speed, u8 *dev_duplex)
+{
+	u32 speed;
+	u8 duplex;
+
+	speed = cmd->base.speed;
+	duplex = cmd->base.duplex;
+	/* don't allow custom speed and duplex */
+	if (!ethtool_validate_speed(speed) ||
+	    !ethtool_validate_duplex(duplex) ||
+	    !ethtool_virtdev_validate_cmd(cmd))
+		return -EINVAL;
+	*dev_speed = speed;
+	*dev_duplex = duplex;
+
+	return 0;
+}
+EXPORT_SYMBOL(ethtool_virtdev_set_link_ksettings);
+
 /* Query device for its ethtool_cmd settings.
  *
  * Backward compatibility note: for compatibility with legacy ethtool, this is