Add devlink commands for devlink device information

This patch adds very basic support for getting information about
devlink devices which are typically PCI devices which exposes Networking
switch or legacy devices.

This information includes bus name, device name and eswitch modes.
This is done through devlink family of commands via generic netlink
sockets provided by Linux kernel.

DevlinkDevice represents a devlink device which is identified by bus
name and device name (unlike interface index for netdevices).
It contains the DevlinkDevAttrs device attributes.
Currently only eswitch attributes are queried. In future more attributes
such as port, shared buffer, traffic class will be added.

Signed-off-by: Parav Pandit <parav@mellanox.com>

devlink_linux.go

@@ -0,0 +1,167 @@
+package netlink
+
+import (
+	"syscall"
+
+	"github.com/vishvananda/netlink/nl"
+	"golang.org/x/sys/unix"
+)
+
+// DevlinkDevEswitchAttr represents device's eswitch attributes
+type DevlinkDevEswitchAttr struct {
+	Mode       string
+	InlineMode string
+	EncapMode  string
+}
+
+// DevlinkDevAttrs represents device attributes
+type DevlinkDevAttrs struct {
+	Eswitch DevlinkDevEswitchAttr
+}
+
+// DevlinkDevice represents device and its attributes
+type DevlinkDevice struct {
+	BusName    string
+	DeviceName string
+	Attrs      DevlinkDevAttrs
+}
+
+func parseDevLinkDeviceList(msgs [][]byte) ([]*DevlinkDevice, error) {
+	devices := make([]*DevlinkDevice, 0, len(msgs))
+	for _, m := range msgs {
+		attrs, err := nl.ParseRouteAttr(m[nl.SizeofGenlmsg:])
+		if err != nil {
+			return nil, err
+		}
+		dev := &DevlinkDevice{}
+		if err = dev.parseAttributes(attrs); err != nil {
+			return nil, err
+		}
+		devices = append(devices, dev)
+	}
+	return devices, nil
+}
+
+func parseEswitchMode(mode uint16) string {
+	var eswitchMode = map[uint16]string{
+		nl.DEVLINK_ESWITCH_MODE_LEGACY:    "legacy",
+		nl.DEVLINK_ESWITCH_MODE_SWITCHDEV: "switchdev",
+	}
+	if eswitchMode[mode] == "" {
+		return "unknown"
+	} else {
+		return eswitchMode[mode]
+	}
+}
+
+func parseEswitchInlineMode(inlinemode uint8) string {
+	var eswitchInlineMode = map[uint8]string{
+		nl.DEVLINK_ESWITCH_INLINE_MODE_NONE:      "none",
+		nl.DEVLINK_ESWITCH_INLINE_MODE_LINK:      "link",
+		nl.DEVLINK_ESWITCH_INLINE_MODE_NETWORK:   "network",
+		nl.DEVLINK_ESWITCH_INLINE_MODE_TRANSPORT: "transport",
+	}
+	if eswitchInlineMode[inlinemode] == "" {
+		return "unknown"
+	} else {
+		return eswitchInlineMode[inlinemode]
+	}
+}
+
+func parseEswitchEncapMode(encapmode uint8) string {
+	var eswitchEncapMode = map[uint8]string{
+		nl.DEVLINK_ESWITCH_ENCAP_MODE_NONE:  "disable",
+		nl.DEVLINK_ESWITCH_ENCAP_MODE_BASIC: "enable",
+	}
+	if eswitchEncapMode[encapmode] == "" {
+		return "unknown"
+	} else {
+		return eswitchEncapMode[encapmode]
+	}
+}
+
+func (d *DevlinkDevice) parseAttributes(attrs []syscall.NetlinkRouteAttr) error {
+	for _, a := range attrs {
+		switch a.Attr.Type {
+		case nl.DEVLINK_ATTR_BUS_NAME:
+			d.BusName = string(a.Value)
+		case nl.DEVLINK_ATTR_DEV_NAME:
+			d.DeviceName = string(a.Value)
+		case nl.DEVLINK_ATTR_ESWITCH_MODE:
+			d.Attrs.Eswitch.Mode = parseEswitchMode(native.Uint16(a.Value))
+		case nl.DEVLINK_ATTR_ESWITCH_INLINE_MODE:
+			d.Attrs.Eswitch.InlineMode = parseEswitchInlineMode(uint8(a.Value[0]))
+		case nl.DEVLINK_ATTR_ESWITCH_ENCAP_MODE:
+			d.Attrs.Eswitch.EncapMode = parseEswitchEncapMode(uint8(a.Value[0]))
+		}
+	}
+	return nil
+}
+
+func (dev *DevlinkDevice) parseEswitchAttrs(msgs [][]byte) {
+	m := msgs[0]
+	attrs, err := nl.ParseRouteAttr(m[nl.SizeofGenlmsg:])
+	if err != nil {
+		return
+	}
+	dev.parseAttributes(attrs)
+}
+
+func (h *Handle) getEswitchAttrs(family *GenlFamily, dev *DevlinkDevice) {
+	msg := &nl.Genlmsg{
+		Command: nl.DEVLINK_CMD_ESWITCH_GET,
+		Version: nl.GENL_DEVLINK_VERSION,
+	}
+	req := h.newNetlinkRequest(int(family.ID), unix.NLM_F_REQUEST|unix.NLM_F_ACK)
+	req.AddData(msg)
+
+	b := make([]byte, len(dev.BusName))
+	copy(b, dev.BusName)
+	data := nl.NewRtAttr(nl.DEVLINK_ATTR_BUS_NAME, b)
+	req.AddData(data)
+
+	b = make([]byte, len(dev.DeviceName))
+	copy(b, dev.DeviceName)
+	data = nl.NewRtAttr(nl.DEVLINK_ATTR_DEV_NAME, b)
+	req.AddData(data)
+
+	msgs, err := req.Execute(unix.NETLINK_GENERIC, 0)
+	if err != nil {
+		return
+	}
+	dev.parseEswitchAttrs(msgs)
+}
+
+// DevLinkGetDeviceList provides a pointer to devlink devices and nil error,
+// otherwise returns an error code.
+func (h *Handle) DevLinkGetDeviceList() ([]*DevlinkDevice, error) {
+	f, err := h.GenlFamilyGet(nl.GENL_DEVLINK_NAME)
+	if err != nil {
+		return nil, err
+	}
+	msg := &nl.Genlmsg{
+		Command: nl.DEVLINK_CMD_GET,
+		Version: nl.GENL_DEVLINK_VERSION,
+	}
+	req := h.newNetlinkRequest(int(f.ID),
+		unix.NLM_F_REQUEST|unix.NLM_F_ACK|unix.NLM_F_DUMP)
+	req.AddData(msg)
+	msgs, err := req.Execute(unix.NETLINK_GENERIC, 0)
+	if err != nil {
+		return nil, err
+	}
+	devices, err := parseDevLinkDeviceList(msgs)
+	if err != nil {
+		return nil, err
+	}
+	for _, d := range devices {
+		h.getEswitchAttrs(f, d)
+	}
+	return devices, nil
+}
+
+// DevLinkGetDeviceList provides a pointer to devlink devices and nil error,
+// otherwise returns an error code.
+func DevLinkGetDeviceList() ([]*DevlinkDevice, error) {
+	return pkgHandle.DevLinkGetDeviceList()
+}

devlink_test.go

@@ -0,0 +1,34 @@
+// +build linux
+
+package netlink
+
+import (
+	"io/ioutil"
+	"strings"
+	"testing"
+)
+
+func setupDevlinkKModule(t *testing.T, name string) {
+	skipUnlessRoot(t)
+	file, err := ioutil.ReadFile("/proc/modules")
+	if err != nil {
+		t.Fatal("Failed to open /proc/modules", err)
+	}
+	for _, line := range strings.Split(string(file), "\n") {
+		n := strings.Split(line, " ")[0]
+		if n == name {
+			return
+		}
+
+	}
+	t.Skipf("Test requires kmodule %q.", name)
+}
+
+func TestDevLinkGetDeviceList(t *testing.T) {
+	minKernelRequired(t, 4, 12)
+	setUpNetlinkTestWithKModule(t, "devlink")
+	_, err := DevLinkGetDeviceList()
+	if err != nil {
+		t.Fatal(err)
+	}
+}

nl/devlink_linux.go

@@ -0,0 +1,39 @@
+package nl
+
+// All the following constants are coming from:
+// https://github.com/torvalds/linux/blob/master/include/uapi/linux/devlink.h
+
+const (
+	GENL_DEVLINK_VERSION = 1
+	GENL_DEVLINK_NAME    = "devlink"
+)
+
+const (
+	DEVLINK_CMD_GET         = 1
+	DEVLINK_CMD_ESWITCH_GET = 29
+)
+
+const (
+	DEVLINK_ATTR_BUS_NAME            = 1
+	DEVLINK_ATTR_DEV_NAME            = 2
+	DEVLINK_ATTR_ESWITCH_MODE        = 25
+	DEVLINK_ATTR_ESWITCH_INLINE_MODE = 26
+	DEVLINK_ATTR_ESWITCH_ENCAP_MODE  = 62
+)
+
+const (
+	DEVLINK_ESWITCH_MODE_LEGACY    = 0
+	DEVLINK_ESWITCH_MODE_SWITCHDEV = 1
+)
+
+const (
+	DEVLINK_ESWITCH_INLINE_MODE_NONE      = 0
+	DEVLINK_ESWITCH_INLINE_MODE_LINK      = 1
+	DEVLINK_ESWITCH_INLINE_MODE_NETWORK   = 2
+	DEVLINK_ESWITCH_INLINE_MODE_TRANSPORT = 3
+)
+
+const (
+	DEVLINK_ESWITCH_ENCAP_MODE_NONE  = 0
+	DEVLINK_ESWITCH_ENCAP_MODE_BASIC = 1
+)