qemu: Add multi-queue and vhost definitions to NetDevice

We can now specify if we want vhost to be enabled and wich fds we should
use for multiqueue support.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

qemu.go

@@ -191,6 +191,13 @@ type NetDevice struct {
 
 	// Script is the tap interface configuration script.
 	Script string
+
+	// FDs represents the list of already existing file descriptors to be used.
+	// This is mostly useful for mq support.
+	FDs []int
+
+	// VHost enables virtio device emulation from the host kernel instead of from qemu.
+	VHost bool
 }
 
 // Config is the qemu configuration structure.
@@ -557,6 +564,20 @@ func appendNetDevices(params []string, config Config) []string {
 				netdevParams = append(netdevParams, fmt.Sprintf(",script=%s", d.Script))
 			}
 
+			if len(d.FDs) > 0 {
+				var fdParams []string
+
+				for _, fd := range d.FDs {
+					fdParams = append(fdParams, fmt.Sprintf("%d", fd))
+				}
+
+				netdevParams = append(netdevParams, fmt.Sprintf(",fds=%s", strings.Join(fdParams, ":")))
+			}
+
+			if d.VHost == true {
+				netdevParams = append(netdevParams, ",vhost=on")
+			}
+
 			params = append(params, "-netdev")
 			params = append(params, strings.Join(netdevParams, ""))
 		}

qemu_test.go

@@ -266,15 +266,16 @@ func TestAppendStrings(t *testing.T) {
 	}
 }
 
-var netdevString = "-netdev tap,id=ceth0,ifname=ceth0,downscript=no,script=no"
+var netdevString = "-netdev tap,id=ceth0,downscript=no,script=no,fds=8:9:10,vhost=on"
 
 func TestAppendNetDevices(t *testing.T) {
 	netdev := NetDevice{
 		Type:       "tap",
 		ID:         "ceth0",
-		IfName:     "ceth0",
 		Script:     "no",
 		DownScript: "no",
+		FDs:        []int{8, 9, 10},
+		VHost:      true,
 	}
 
 	testAppend(netdev, netdevString, t)