devlink: Support setting max_io_eqs

Many devices send event notifications for the IO queues,
such as tx and rx queues, through event queues.

Enable a privileged owner, such as a hypervisor PF, to set the number
of IO event queues for the VF and SF during the provisioning stage.

example:
Get maximum IO event queues of the VF device::

  $ 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 00:00:00:00:00:00 ipsec_packet disabled max_io_eqs 10

Set maximum IO event queues of the VF device::

  $ devlink port function set pci/0000:06:00.0/2 max_io_eqs 32

  $ 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 00:00:00:00:00:00 ipsec_packet disabled max_io_eqs 32
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Shay Drory <shayd@nvidia.com>
Signed-off-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/devlink/devlink-port.rst

@@ -134,6 +134,9 @@ Users may also set the IPsec crypto capability of the function using
 Users may also set the IPsec packet capability of the function using
 `devlink port function set ipsec_packet` command.
 
+Users may also set the maximum IO event queues of the function
+using `devlink port function set max_io_eqs` command.
+
 Function attributes
 ===================
 
@@ -295,6 +298,36 @@ policy is processed in software by the kernel.
         function:
             hw_addr 00:00:00:00:00:00 ipsec_packet enabled
 
+Maximum IO events queues setup
+------------------------------
+When user sets maximum number of IO event queues for a SF or
+a VF, such function driver is limited to consume only enforced
+number of IO event queues.
+
+IO event queues deliver events related to IO queues, including network
+device transmit and receive queues (txq and rxq) and RDMA Queue Pairs (QPs).
+For example, the number of netdevice channels and RDMA device completion
+vectors are derived from the function's IO event queues. Usually, the number
+of interrupt vectors consumed by the driver is limited by the number of IO
+event queues per device, as each of the IO event queues is connected to an
+interrupt vector.
+
+- Get maximum IO event queues of the VF device::
+
+    $ 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 00:00:00:00:00:00 ipsec_packet disabled max_io_eqs 10
+
+- Set maximum IO event queues of the VF device::
+
+    $ devlink port function set pci/0000:06:00.0/2 max_io_eqs 32
+
+    $ 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 00:00:00:00:00:00 ipsec_packet disabled max_io_eqs 32
+
 Subfunction
 ============
 

include/net/devlink.h

@@ -1602,6 +1602,14 @@ void devlink_free(struct devlink *devlink);
  *			      capability. Should be used by device drivers to
  *			      enable/disable ipsec_packet capability of a
  *			      function managed by the devlink port.
+ * @port_fn_max_io_eqs_get: Callback used to get port function's maximum number
+ *			    of event queues. Should be used by device drivers to
+ *			    report the maximum event queues of a function
+ *			    managed by the devlink port.
+ * @port_fn_max_io_eqs_set: Callback used to set port function's maximum number
+ *			    of event queues. Should be used by device drivers to
+ *			    configure maximum number of event queues
+ *			    of a function managed by the devlink port.
  *
  * Note: Driver should return -EOPNOTSUPP if it doesn't support
  * port function (@port_fn_*) handling for a particular port.
@@ -1651,6 +1659,12 @@ struct devlink_port_ops {
 	int (*port_fn_ipsec_packet_set)(struct devlink_port *devlink_port,
 					bool enable,
 					struct netlink_ext_ack *extack);
+	int (*port_fn_max_io_eqs_get)(struct devlink_port *devlink_port,
+				      u32 *max_eqs,
+				      struct netlink_ext_ack *extack);
+	int (*port_fn_max_io_eqs_set)(struct devlink_port *devlink_port,
+				      u32 max_eqs,
+				      struct netlink_ext_ack *extack);
 };
 
 void devlink_port_init(struct devlink *devlink,

include/uapi/linux/devlink.h

@@ -686,6 +686,7 @@ enum devlink_port_function_attr {
 	DEVLINK_PORT_FN_ATTR_OPSTATE,	/* u8 */
 	DEVLINK_PORT_FN_ATTR_CAPS,	/* bitfield32 */
 	DEVLINK_PORT_FN_ATTR_DEVLINK,	/* nested */
+	DEVLINK_PORT_FN_ATTR_MAX_IO_EQS,	/* u32 */
 
 	__DEVLINK_PORT_FUNCTION_ATTR_MAX,
 	DEVLINK_PORT_FUNCTION_ATTR_MAX = __DEVLINK_PORT_FUNCTION_ATTR_MAX - 1

net/devlink/port.c

@@ -16,6 +16,7 @@ static const struct nla_policy devlink_function_nl_policy[DEVLINK_PORT_FUNCTION_
 				 DEVLINK_PORT_FN_STATE_ACTIVE),
 	[DEVLINK_PORT_FN_ATTR_CAPS] =
 		NLA_POLICY_BITFIELD32(DEVLINK_PORT_FN_CAPS_VALID_MASK),
+	[DEVLINK_PORT_FN_ATTR_MAX_IO_EQS] = { .type = NLA_U32 },
 };
 
 #define ASSERT_DEVLINK_PORT_REGISTERED(devlink_port)				\
@@ -182,6 +183,30 @@ static int devlink_port_fn_caps_fill(struct devlink_port *devlink_port,
 	return 0;
 }
 
+static int devlink_port_fn_max_io_eqs_fill(struct devlink_port *port,
+					   struct sk_buff *msg,
+					   struct netlink_ext_ack *extack,
+					   bool *msg_updated)
+{
+	u32 max_io_eqs;
+	int err;
+
+	if (!port->ops->port_fn_max_io_eqs_get)
+		return 0;
+
+	err = port->ops->port_fn_max_io_eqs_get(port, &max_io_eqs, extack);
+	if (err) {
+		if (err == -EOPNOTSUPP)
+			return 0;
+		return err;
+	}
+	err = nla_put_u32(msg, DEVLINK_PORT_FN_ATTR_MAX_IO_EQS, max_io_eqs);
+	if (err)
+		return err;
+	*msg_updated = true;
+	return 0;
+}
+
 int devlink_nl_port_handle_fill(struct sk_buff *msg, struct devlink_port *devlink_port)
 {
 	if (devlink_nl_put_handle(msg, devlink_port->devlink))
@@ -409,6 +434,18 @@ static int devlink_port_fn_caps_set(struct devlink_port *devlink_port,
 	return 0;
 }
 
+static int
+devlink_port_fn_max_io_eqs_set(struct devlink_port *devlink_port,
+			       const struct nlattr *attr,
+			       struct netlink_ext_ack *extack)
+{
+	u32 max_io_eqs;
+
+	max_io_eqs = nla_get_u32(attr);
+	return devlink_port->ops->port_fn_max_io_eqs_set(devlink_port,
+							 max_io_eqs, extack);
+}
+
 static int
 devlink_nl_port_function_attrs_put(struct sk_buff *msg, struct devlink_port *port,
 				   struct netlink_ext_ack *extack)
@@ -428,6 +465,9 @@ devlink_nl_port_function_attrs_put(struct sk_buff *msg, struct devlink_port *por
 	if (err)
 		goto out;
 	err = devlink_port_fn_state_fill(port, msg, extack, &msg_updated);
+	if (err)
+		goto out;
+	err = devlink_port_fn_max_io_eqs_fill(port, msg, extack, &msg_updated);
 	if (err)
 		goto out;
 	err = devlink_rel_devlink_handle_put(msg, port->devlink,
@@ -726,6 +766,12 @@ static int devlink_port_function_validate(struct devlink_port *devlink_port,
 			}
 		}
 	}
+	if (tb[DEVLINK_PORT_FN_ATTR_MAX_IO_EQS] &&
+	    !ops->port_fn_max_io_eqs_set) {
+		NL_SET_ERR_MSG_ATTR(extack, tb[DEVLINK_PORT_FN_ATTR_MAX_IO_EQS],
+				    "Function does not support max_io_eqs setting");
+		return -EOPNOTSUPP;
+	}
 	return 0;
 }
 
@@ -761,6 +807,13 @@ static int devlink_port_function_set(struct devlink_port *port,
 			return err;
 	}
 
+	attr = tb[DEVLINK_PORT_FN_ATTR_MAX_IO_EQS];
+	if (attr) {
+		err = devlink_port_fn_max_io_eqs_set(port, attr, extack);
+		if (err)
+			return err;
+	}
+
 	/* Keep this as the last function attribute set, so that when
 	 * multiple port function attributes are set along with state,
 	 * Those can be applied first before activating the state.