[PATCH net-next v2 6/7] devlink: introduce port's peer netdevs

[Jakub Kicinski <jakub.kicinski@netronome.com>]

Devlink ports represent ports of a switch device (or SR-IOV
NIC which has an embedded switch). In case of SR-IOV when
PCIe PFs are exposed the PFs which are directly connected
to the local machine may also spawn PF netdev (much like
VFs have a port/"repr" and an actual VF netdev).

Allow devlink to expose such linking. There is currently no
way to find out which netdev corresponds to which PF.

Example:

$ devlink port
pci/0000:82:00.0/0: type eth netdev p4p1 flavour physical
pci/0000:82:00.0/10000: type eth netdev eth1 flavour pci_pf pf 0 peer_netdev enp130s0
pci/0000:82:00.0/10001: type eth netdev eth0 flavour pci_vf pf 0 vf 0
pci/0000:82:00.0/10002: type eth netdev eth2 flavour pci_vf pf 0 vf 1

v2: - move the peer info into a nested attr.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
---
 include/net/devlink.h        | 11 ++++++
 include/uapi/linux/devlink.h |  6 ++++
 net/core/devlink.c           | 68 +++++++++++++++++++++++++++++++++---
 3 files changed, 81 insertions(+), 4 deletions(-)

diff --git a/include/net/devlink.h b/include/net/devlink.h
index 6a29ce80cb38..f3ced79a30a8 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -68,6 +68,7 @@ struct devlink_port {
 	enum devlink_port_type type;
 	enum devlink_port_type desired_type;
 	void *type_dev;
+	void *type_peer;
 	struct devlink_port_attrs attrs;
 };
 
@@ -573,6 +574,9 @@ int devlink_port_register(struct devlink *devlink,
 void devlink_port_unregister(struct devlink_port *devlink_port);
 void devlink_port_type_eth_set(struct devlink_port *devlink_port,
 			       struct net_device *netdev);
+void devlink_port_type_eth_set_peer(struct devlink_port *devlink_port,
+				    struct net_device *netdev,
+				    struct net_device *peer);
 void devlink_port_type_ib_set(struct devlink_port *devlink_port,
 			      struct ib_device *ibdev);
 void devlink_port_type_clear(struct devlink_port *devlink_port);
@@ -784,6 +788,13 @@ static inline void devlink_port_type_eth_set(struct devlink_port *devlink_port,
 {
 }
 
+static inline void
+devlink_port_type_eth_set_peer(struct devlink_port *devlink_port,
+			       struct net_device *netdev,
+			       struct net_device *peer)
+{
+}
+
 static inline void devlink_port_type_ib_set(struct devlink_port *devlink_port,
 					    struct ib_device *ibdev)
 {
diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
index 417ae8233cce..34ed03bee9fc 100644
--- a/include/uapi/linux/devlink.h
+++ b/include/uapi/linux/devlink.h
@@ -338,6 +338,12 @@ enum devlink_attr {
 	DEVLINK_ATTR_PORT_PCI_VF_NUMBER,	/* u32 */
 	DEVLINK_ATTR_PORT_PCI_SUBPORT,		/* u32 */
 
+	DEVLINK_ATTR_PORT_PEER,			/* nested */
+	DEVLINK_ATTR_PORT_PEER_TYPE,		/* u16 */
+	DEVLINK_ATTR_PORT_PEER_NETDEV_IFINDEX,	/* u32 */
+	DEVLINK_ATTR_PORT_PEER_NETDEV_NAME,	/* string */
+	DEVLINK_ATTR_PORT_PEER_IBDEV_NAME,	/* string */
+
 	/* add new attributes above here, update the policy in devlink.c */
 
 	__DEVLINK_ATTR_MAX,
diff --git a/net/core/devlink.c b/net/core/devlink.c
index a7dd958be513..75c313b5b616 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -552,6 +552,47 @@ static int devlink_nl_port_attrs_put(struct sk_buff *msg,
 	}
 }
 
+static int devlink_nl_port_peer_put(struct sk_buff *msg,
+				    struct devlink_port *devlink_port)
+{
+	struct nlattr *peer_attr;
+
+	if (!devlink_port->type_peer)
+		return 0;
+
+	peer_attr = nla_nest_start(msg, DEVLINK_ATTR_PORT_PEER);
+	if (!peer_attr)
+		return -EMSGSIZE;
+
+	/* Peer's type is got to be the same as the port's type */
+	if (nla_put_u16(msg, DEVLINK_ATTR_PORT_PEER_TYPE, devlink_port->type))
+		goto cancel_peer_attr;
+
+	if (devlink_port->type == DEVLINK_PORT_TYPE_ETH) {
+		struct net_device *netdev = devlink_port->type_peer;
+
+		if (nla_put_u32(msg, DEVLINK_ATTR_PORT_PEER_NETDEV_IFINDEX,
+				netdev->ifindex) ||
+		    nla_put_string(msg, DEVLINK_ATTR_PORT_PEER_NETDEV_NAME,
+				   netdev->name))
+			goto cancel_peer_attr;
+	}
+	if (devlink_port->type == DEVLINK_PORT_TYPE_IB) {
+		struct ib_device *ibdev = devlink_port->type_peer;
+
+		if (ibdev &&
+		    nla_put_string(msg, DEVLINK_ATTR_PORT_PEER_IBDEV_NAME,
+				   ibdev->name))
+			goto cancel_peer_attr;
+	}
+	nla_nest_end(msg, peer_attr);
+	return 0;
+
+cancel_peer_attr:
+	nla_nest_cancel(msg, peer_attr);
+	return -EMSGSIZE;
+}
+
 static int devlink_nl_port_fill(struct sk_buff *msg, struct devlink *devlink,
 				struct devlink_port *devlink_port,
 				enum devlink_command cmd, u32 portid,
@@ -593,6 +634,8 @@ static int devlink_nl_port_fill(struct sk_buff *msg, struct devlink *devlink,
 	}
 	if (devlink_nl_port_attrs_put(msg, devlink_port))
 		goto nla_put_failure;
+	if (devlink_nl_port_peer_put(msg, devlink_port))
+		goto nla_put_failure;
 
 	genlmsg_end(msg, hdr);
 	return 0;
@@ -5370,10 +5413,11 @@ EXPORT_SYMBOL_GPL(devlink_port_unregister);
 
 static void __devlink_port_type_set(struct devlink_port *devlink_port,
 				    enum devlink_port_type type,
-				    void *type_dev)
+				    void *type_dev, void *type_peer)
 {
 	devlink_port->type = type;
 	devlink_port->type_dev = type_dev;
+	devlink_port->type_peer = type_peer;
 	devlink_port_notify(devlink_port, DEVLINK_CMD_PORT_NEW);
 }
 
@@ -5387,10 +5431,26 @@ void devlink_port_type_eth_set(struct devlink_port *devlink_port,
 			       struct net_device *netdev)
 {
 	return __devlink_port_type_set(devlink_port,
-				       DEVLINK_PORT_TYPE_ETH, netdev);
+				       DEVLINK_PORT_TYPE_ETH, netdev, NULL);
 }
 EXPORT_SYMBOL_GPL(devlink_port_type_eth_set);
 
+/**
+ *	devlink_port_type_eth_set_peer - Set port type to Ethernet with peer
+ *
+ *	@devlink_port: devlink port
+ *	@netdev: related netdevice
+ *	@peer: for PCIe ports the non-port netdev (actual VF or PF)
+ */
+void devlink_port_type_eth_set_peer(struct devlink_port *devlink_port,
+				    struct net_device *netdev,
+				    struct net_device *peer)
+{
+	return __devlink_port_type_set(devlink_port,
+				       DEVLINK_PORT_TYPE_ETH, netdev, peer);
+}
+EXPORT_SYMBOL_GPL(devlink_port_type_eth_set_peer);
+
 /**
  *	devlink_port_type_ib_set - Set port type to InfiniBand
  *
@@ -5401,7 +5461,7 @@ void devlink_port_type_ib_set(struct devlink_port *devlink_port,
 			      struct ib_device *ibdev)
 {
 	return __devlink_port_type_set(devlink_port,
-				       DEVLINK_PORT_TYPE_IB, ibdev);
+				       DEVLINK_PORT_TYPE_IB, ibdev, NULL);
 }
 EXPORT_SYMBOL_GPL(devlink_port_type_ib_set);
 
@@ -5413,7 +5473,7 @@ EXPORT_SYMBOL_GPL(devlink_port_type_ib_set);
 void devlink_port_type_clear(struct devlink_port *devlink_port)
 {
 	return __devlink_port_type_set(devlink_port,
-				       DEVLINK_PORT_TYPE_NOTSET, NULL);
+				       DEVLINK_PORT_TYPE_NOTSET, NULL, NULL);
 }
 EXPORT_SYMBOL_GPL(devlink_port_type_clear);
 
-- 
2.19.2