host-device: Add support for DPDK device (#490)

This commit would make host-device plugin as a placeholder
for DPDK device when applications wants to attach it with
a pod container through network attachment definition.

Signed-off-by: Periyasamy Palanisamy <periyasamy.palanisamy@est.tech>

plugins/main/host-device/host-device.go

@@ -43,6 +43,9 @@ const (
 	sysBusPCI = "/sys/bus/pci/devices"
 )
 
+// Array of different linux drivers bound to network device needed for DPDK
+var userspaceDrivers = []string{"vfio-pci", "uio_pci_generic", "igb_uio"}
+
 //NetConf for host-device config, look the README to learn how to use those parameters
 type NetConf struct {
 	types.NetConf
@@ -91,6 +94,16 @@ func cmdAdd(args *skel.CmdArgs) error {
 	}
 	defer containerNs.Close()
 
+	if len(cfg.PCIAddr) > 0 {
+		isDpdkMode, err := hasDpdkDriver(cfg.PCIAddr)
+		if err != nil {
+			return fmt.Errorf("error with host device: %v", err)
+		}
+		if isDpdkMode {
+			return types.PrintResult(&current.Result{}, cfg.CNIVersion)
+		}
+	}
+
 	hostDev, err := getLink(cfg.Device, cfg.HWAddr, cfg.KernelPath, cfg.PCIAddr)
 	if err != nil {
 		return fmt.Errorf("failed to find host device: %v", err)
@@ -168,6 +181,16 @@ func cmdDel(args *skel.CmdArgs) error {
 	}
 	defer containerNs.Close()
 
+	if len(cfg.PCIAddr) > 0 {
+		isDpdkMode, err := hasDpdkDriver(cfg.PCIAddr)
+		if err != nil {
+			return fmt.Errorf("error with host device: %v", err)
+		}
+		if isDpdkMode {
+			return nil
+		}
+	}
+
 	if err := moveLinkOut(containerNs, args.IfName); err != nil {
 		return err
 	}
@@ -255,6 +278,25 @@ func moveLinkOut(containerNs ns.NetNS, ifName string) error {
 	})
 }
 
+func hasDpdkDriver(pciaddr string) (bool, error) {
+	driverLink := filepath.Join(sysBusPCI, pciaddr, "driver")
+	driverPath, err := filepath.EvalSymlinks(driverLink)
+	if err != nil {
+		return false, err
+	}
+	driverStat, err := os.Stat(driverPath)
+	if err != nil {
+		return false, err
+	}
+	driverName := driverStat.Name()
+	for _, drv := range userspaceDrivers {
+		if driverName == drv {
+			return true, nil
+		}
+	}
+	return false, nil
+}
+
 func printLink(dev netlink.Link, cniVersion string, containerNs ns.NetNS) error {
 	result := current.Result{
 		CNIVersion: current.ImplementedSpecVersion,