net/devlink: Support querying hardware address of port function

PCI PF and VF devlink port can manage the function represented by
a devlink port.

Enable users to query port function's hardware address.

Example of a PCI VF port which supports a port function:
$ devlink port show pci/0000:06:00.0/2
pci/0000:06:00.0/2: type eth netdev enp6s0pf0vf1 flavour pcivf pfnum 0 vfnum 1
  function:
    hw_addr 00:11:22:33:44:66

$ devlink port show pci/0000:06:00.0/2 -jp
{
    "port": {
        "pci/0000:06:00.0/2": {
            "type": "eth",
            "netdev": "enp6s0pf0vf1",
            "flavour": "pcivf",
            "pfnum": 0,
            "vfnum": 1,
            "function": {
                "hw_addr": "00:11:22:33:44:66"
            }
        }
    }
}

Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 45 insertions, 0 deletions

diff --git a/net/core/devlink.c b/net/core/devlink.c
index 05197631d52a..b6848b607e9c 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -563,6 +563,49 @@ static int devlink_nl_port_attrs_put(struct sk_buff *msg,
 	return 0;
 }
 
+static int
+devlink_nl_port_function_attrs_put(struct sk_buff *msg, struct devlink_port *port,
+				   struct netlink_ext_ack *extack)
+{
+	struct devlink *devlink = port->devlink;
+	const struct devlink_ops *ops;
+	struct nlattr *function_attr;
+	bool empty_nest = true;
+	int err = 0;
+
+	function_attr = nla_nest_start_noflag(msg, DEVLINK_ATTR_PORT_FUNCTION);
+	if (!function_attr)
+		return -EMSGSIZE;
+
+	ops = devlink->ops;
+	if (ops->port_function_hw_addr_get) {
+		int uninitialized_var(hw_addr_len);
+		u8 hw_addr[MAX_ADDR_LEN];
+
+		err = ops->port_function_hw_addr_get(devlink, port, hw_addr, &hw_addr_len, extack);
+		if (err == -EOPNOTSUPP) {
+			/* Port function attributes are optional for a port. If port doesn't
+			 * support function attribute, returning -EOPNOTSUPP is not an error.
+			 */
+			err = 0;
+			goto out;
+		} else if (err) {
+			goto out;
+		}
+		err = nla_put(msg, DEVLINK_PORT_FUNCTION_ATTR_HW_ADDR, hw_addr_len, hw_addr);
+		if (err)
+			goto out;
+		empty_nest = false;
+	}
+
+out:
+	if (err || empty_nest)
+		nla_nest_cancel(msg, function_attr);
+	else
+		nla_nest_end(msg, function_attr);
+	return err;
+}
+
 static int devlink_nl_port_fill(struct sk_buff *msg, struct devlink *devlink,
 				struct devlink_port *devlink_port,
 				enum devlink_command cmd, u32 portid,
@@ -608,6 +651,8 @@ static int devlink_nl_port_fill(struct sk_buff *msg, struct devlink *devlink,
 	spin_unlock_bh(&devlink_port->type_lock);
 	if (devlink_nl_port_attrs_put(msg, devlink_port))
 		goto nla_put_failure;
+	if (devlink_nl_port_function_attrs_put(msg, devlink_port, extack))
+		goto nla_put_failure;
 
 	genlmsg_end(msg, hdr);
 	return 0;