RDMA/nldev: Add support for RDMA monitoring

Introduce a new netlink command to allow rdma event monitoring.
The rdma events supported now are IB device
registration/unregistration and net device attachment/detachment.

Example output of rdma monitor and the commands which trigger
the events:

$ rdma monitor
$ rmmod mlx5_ib
[UNREGISTER] dev 1 rocep8s0f1
[UNREGISTER] dev 0 rocep8s0f0

$ modprobe mlx5_ib
[REGISTER] dev 2 mlx5_0
[NETDEV_ATTACH] dev 2 mlx5_0 port 1 netdev 4 eth2
[REGISTER] dev 3 mlx5_1
[NETDEV_ATTACH] dev 3 mlx5_1 port 1 netdev 5 eth3

$ devlink dev eswitch set pci/0000:08:00.0 mode switchdev
[UNREGISTER] dev 2 rocep8s0f0
[REGISTER] dev 4 mlx5_0
[NETDEV_ATTACH] dev 4 mlx5_0 port 30 netdev 4 eth2

$ echo 4 > /sys/class/net/eth2/device/sriov_numvfs
[NETDEV_ATTACH] dev 4 rdmap8s0f0 port 2 netdev 7 eth4
[NETDEV_ATTACH] dev 4 rdmap8s0f0 port 3 netdev 8 eth5
[NETDEV_ATTACH] dev 4 rdmap8s0f0 port 4 netdev 9 eth6
[NETDEV_ATTACH] dev 4 rdmap8s0f0 port 5 netdev 10 eth7
[REGISTER] dev 5 mlx5_0
[NETDEV_ATTACH] dev 5 mlx5_0 port 1 netdev 11 eth8
[REGISTER] dev 6 mlx5_0
[NETDEV_ATTACH] dev 6 mlx5_0 port 1 netdev 12 eth9
[REGISTER] dev 7 mlx5_0
[NETDEV_ATTACH] dev 7 mlx5_0 port 1 netdev 13 eth10
[REGISTER] dev 8 mlx5_0
[NETDEV_ATTACH] dev 8 mlx5_0 port 1 netdev 14 eth11

$ echo 0 > /sys/class/net/eth2/device/sriov_numvfs
[UNREGISTER] dev 5 rocep8s0f0v0
[UNREGISTER] dev 6 rocep8s0f0v1
[UNREGISTER] dev 7 rocep8s0f0v2
[UNREGISTER] dev 8 rocep8s0f0v3
[NETDEV_DETACH] dev 4 rdmap8s0f0 port 2
[NETDEV_DETACH] dev 4 rdmap8s0f0 port 3
[NETDEV_DETACH] dev 4 rdmap8s0f0 port 4
[NETDEV_DETACH] dev 4 rdmap8s0f0 port 5

Signed-off-by: Chiara Meiohas <[e-mail]>
Signed-off-by: Michael Guralnik <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Leon Romanovsky <[e-mail]>

drivers/infiniband/core/device.c

···
 {
 }
 
+static void ib_device_notify_register(struct ib_device *device)
+{
+	struct net_device *netdev;
+	u32 port;
+	int ret;
+
+	ret = rdma_nl_notify_event(device, 0, RDMA_REGISTER_EVENT);
+	if (ret)
+		return;
+
+	rdma_for_each_port(device, port) {
+		netdev = ib_device_get_netdev(device, port);
+		if (!netdev)
+			continue;
+
+		ret = rdma_nl_notify_event(device, port,
+					   RDMA_NETDEV_ATTACH_EVENT);
+		dev_put(netdev);
+		if (ret)
+			return;
+	}
+}
+
 /**
  * ib_register_device - Register an IB device with IB core
  * @device: Device to register
···
 	dev_set_uevent_suppress(&device->dev, false);
 	/* Mark for userspace that device is ready */
 	kobject_uevent(&device->dev.kobj, KOBJ_ADD);
+
+	ib_device_notify_register(device);
 	ib_device_put(device);
 
 	return 0;
···
 		goto out;
 
 	disable_device(ib_dev);
+	rdma_nl_notify_event(ib_dev, 0, RDMA_UNREGISTER_EVENT);
 
 	/* Expedite removing unregistered pointers from the hash table */
 	free_netdevs(ib_dev);
···
 int ib_device_set_netdev(struct ib_device *ib_dev, struct net_device *ndev,
 			 u32 port)
 {
+	enum rdma_nl_notify_event_type etype;
 	struct net_device *old_ndev;
 	struct ib_port_data *pdata;
 	unsigned long flags;
···
 	spin_unlock_irqrestore(&pdata->netdev_lock, flags);
 
 	add_ndev_hash(pdata);
+
+	/* Make sure that the device is registered before we send events */
+	if (xa_load(&devices, ib_dev->index) != ib_dev)
+		return 0;
+
+	etype = ndev ? RDMA_NETDEV_ATTACH_EVENT : RDMA_NETDEV_DETACH_EVENT;
+	rdma_nl_notify_event(ib_dev, port, etype);
+
 	return 0;
 }
 EXPORT_SYMBOL(ib_device_set_netdev);

drivers/infiniband/core/netlink.c

···
 	struct net *net = read_pnet(&rnet->net);
 	struct netlink_kernel_cfg cfg = {
 		.input	= rdma_nl_rcv,
+		.flags = NL_CFG_F_NONROOT_RECV,
 	};
 	struct sock *nls;
 

drivers/infiniband/core/nldev.c

···
 	[RDMA_NLDEV_ATTR_DEV_TYPE]		= { .type = NLA_U8 },
 	[RDMA_NLDEV_ATTR_PARENT_NAME]		= { .type = NLA_NUL_STRING },
 	[RDMA_NLDEV_ATTR_NAME_ASSIGN_TYPE]	= { .type = NLA_U8 },
+	[RDMA_NLDEV_ATTR_EVENT_TYPE]		= { .type = NLA_U8 },
 };
 
 static int put_driver_name_print_type(struct sk_buff *msg, const char *name,
···
 		.flags = RDMA_NL_ADMIN_PERM,
 	},
 };
+
+static int fill_mon_netdev_association(struct sk_buff *msg,
+				       struct ib_device *device, u32 port,
+				       const struct net *net)
+{
+	struct net_device *netdev = ib_device_get_netdev(device, port);
+	int ret = 0;
+
+	if (netdev && !net_eq(dev_net(netdev), net))
+		goto out;
+
+	ret = nla_put_u32(msg, RDMA_NLDEV_ATTR_DEV_INDEX, device->index);
+	if (ret)
+		goto out;
+
+	ret = nla_put_string(msg, RDMA_NLDEV_ATTR_DEV_NAME,
+			     dev_name(&device->dev));
+	if (ret)
+		goto out;
+
+	ret = nla_put_u32(msg, RDMA_NLDEV_ATTR_PORT_INDEX, port);
+	if (ret)
+		goto out;
+
+	if (netdev) {
+		ret = nla_put_u32(msg,
+				  RDMA_NLDEV_ATTR_NDEV_INDEX, netdev->ifindex);
+		if (ret)
+			goto out;
+
+		ret = nla_put_string(msg,
+				     RDMA_NLDEV_ATTR_NDEV_NAME, netdev->name);
+	}
+
+out:
+	dev_put(netdev);
+	return ret;
+}
+
+static void rdma_nl_notify_err_msg(struct ib_device *device, u32 port_num,
+				    enum rdma_nl_notify_event_type type)
+{
+	struct net_device *netdev;
+
+	switch (type) {
+	case RDMA_REGISTER_EVENT:
+		dev_warn_ratelimited(&device->dev,
+				     "Failed to send RDMA monitor register device event\n");
+		break;
+	case RDMA_UNREGISTER_EVENT:
+		dev_warn_ratelimited(&device->dev,
+				     "Failed to send RDMA monitor unregister device event\n");
+		break;
+	case RDMA_NETDEV_ATTACH_EVENT:
+		netdev = ib_device_get_netdev(device, port_num);
+		dev_warn_ratelimited(&device->dev,
+				     "Failed to send RDMA monitor netdev attach event: port %d netdev %d\n",
+				     port_num, netdev->ifindex);
+		dev_put(netdev);
+		break;
+	case RDMA_NETDEV_DETACH_EVENT:
+		dev_warn_ratelimited(&device->dev,
+				     "Failed to send RDMA monitor netdev detach event: port %d\n",
+				     port_num);
+	default:
+		break;
+	}
+}
+
+int rdma_nl_notify_event(struct ib_device *device, u32 port_num,
+			  enum rdma_nl_notify_event_type type)
+{
+	struct sk_buff *skb;
+	struct net *net;
+	int ret = 0;
+	void *nlh;
+
+	net = read_pnet(&device->coredev.rdma_net);
+	if (!net)
+		return -EINVAL;
+
+	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
+	nlh = nlmsg_put(skb, 0, 0,
+			RDMA_NL_GET_TYPE(RDMA_NL_NLDEV, RDMA_NLDEV_CMD_MONITOR),
+			0, 0);
+
+	switch (type) {
+	case RDMA_REGISTER_EVENT:
+	case RDMA_UNREGISTER_EVENT:
+		ret = fill_nldev_handle(skb, device);
+		if (ret)
+			goto err_free;
+		break;
+	case RDMA_NETDEV_ATTACH_EVENT:
+	case RDMA_NETDEV_DETACH_EVENT:
+		ret = fill_mon_netdev_association(skb, device,
+						  port_num, net);
+		if (ret)
+			goto err_free;
+		break;
+	default:
+		break;
+	}
+
+	ret = nla_put_u8(skb, RDMA_NLDEV_ATTR_EVENT_TYPE, type);
+	if (ret)
+		goto err_free;
+
+	nlmsg_end(skb, nlh);
+	ret = rdma_nl_multicast(net, skb, RDMA_NL_GROUP_NOTIFY, GFP_KERNEL);
+	if (ret && ret != -ESRCH) {
+		skb = NULL; /* skb is freed in the netlink send-op handling */
+		goto err_free;
+	}
+	return 0;
+
+err_free:
+	rdma_nl_notify_err_msg(device, port_num, type);
+	nlmsg_free(skb);
+	return ret;
+}
 
 void __init nldev_init(void)
 {

include/rdma/rdma_netlink.h

···
 #include <linux/netlink.h>
 #include <uapi/rdma/rdma_netlink.h>
 
+struct ib_device;
+
 enum {
 	RDMA_NLDEV_ATTR_EMPTY_STRING = 1,
 	RDMA_NLDEV_ATTR_ENTRY_STRLEN = 16,
···
  * Returns true on success or false if no listeners.
  */
 bool rdma_nl_chk_listeners(unsigned int group);
+
+/**
+ * Prepare and send an event message
+ * @ib: the IB device which triggered the event
+ * @port_num: the port number which triggered the event - 0 if unused
+ * @type: the event type
+ * Returns 0 on success or a negative error code
+ */
+int rdma_nl_notify_event(struct ib_device *ib, u32 port_num,
+			 enum rdma_nl_notify_event_type type);
 
 struct rdma_link_ops {
 	struct list_head list;

include/uapi/rdma/rdma_netlink.h

···
 enum {
 	RDMA_NL_GROUP_IWPM = 2,
 	RDMA_NL_GROUP_LS,
+	RDMA_NL_GROUP_NOTIFY,
 	RDMA_NL_NUM_GROUPS
 };
 
···
 
 	RDMA_NLDEV_CMD_DELDEV,
 
+	RDMA_NLDEV_CMD_MONITOR,
+
 	RDMA_NLDEV_NUM_OPS
 };
 
···
 
 	RDMA_NLDEV_ATTR_NAME_ASSIGN_TYPE,	/* u8 */
 
+	RDMA_NLDEV_ATTR_EVENT_TYPE,		/* u8 */
+
 	/*
 	 * Always the end
 	 */
···
 enum rdma_nl_name_assign_type {
 	RDMA_NAME_ASSIGN_TYPE_UNKNOWN = 0,
 	RDMA_NAME_ASSIGN_TYPE_USER = 1, /* Provided by user-space */
+};
+
+/*
+ * Supported rdma monitoring event types.
+ */
+enum rdma_nl_notify_event_type {
+	RDMA_REGISTER_EVENT,
+	RDMA_UNREGISTER_EVENT,
+	RDMA_NETDEV_ATTACH_EVENT,
+	RDMA_NETDEV_DETACH_EVENT,
 };
 
 #endif /* _UAPI_RDMA_NETLINK_H */