mlxsw: spectrum_switchdev: Add more extack messages

Add more extack messages that let the user know why VXLAN offload
failed.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Suggested-by: David Ahern <dsahern@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c

@@ -2027,6 +2027,7 @@ mlxsw_sp_bridge_8021q_vxlan_join(struct mlxsw_sp_bridge_device *bridge_device,
 		return 0;
 
 	if (mlxsw_sp_fid_vni_is_set(fid)) {
+		NL_SET_ERR_MSG_MOD(extack, "VNI is already set on FID");
 		err = -EINVAL;
 		goto err_vni_exists;
 	}
@@ -2213,10 +2214,13 @@ mlxsw_sp_bridge_8021d_vxlan_join(struct mlxsw_sp_bridge_device *bridge_device,
 	int err;
 
 	fid = mlxsw_sp_fid_8021d_lookup(mlxsw_sp, bridge_device->dev->ifindex);
-	if (!fid)
+	if (!fid) {
+		NL_SET_ERR_MSG_MOD(extack, "Did not find a corresponding FID");
 		return -EINVAL;
+	}
 
 	if (mlxsw_sp_fid_vni_is_set(fid)) {
+		NL_SET_ERR_MSG_MOD(extack, "VNI is already set on FID");
 		err = -EINVAL;
 		goto err_vni_exists;
 	}
@@ -3231,8 +3235,10 @@ mlxsw_sp_switchdev_vxlan_vlan_add(struct mlxsw_sp *mlxsw_sp,
 	 * the lookup function to return 'vxlan_dev'
 	 */
 	if (flag_untagged && flag_pvid &&
-	    mlxsw_sp_bridge_8021q_vxlan_dev_find(bridge_device->dev, vid))
+	    mlxsw_sp_bridge_8021q_vxlan_dev_find(bridge_device->dev, vid)) {
+		NL_SET_ERR_MSG_MOD(extack, "VLAN already mapped to a different VNI");
 		return -EINVAL;
+	}
 
 	if (!netif_running(vxlan_dev))
 		return 0;