qemu: add vhost-user-fs-pci device instead of 9p

When enable_virtio_fs is true, add a vhost-user-fs-pci for the
kataShared volume instead of 9p.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

virtcontainers/device/config/config.go

@@ -36,6 +36,9 @@ const (
 
 	//VhostUserBlk represents a block vhostuser device type
 	VhostUserBlk = "vhost-user-blk-pci"
+
+	//VhostUserFS represents a virtio-fs vhostuser device type
+	VhostUserFS = "vhost-user-fs-pci"
 )
 
 const (
@@ -182,6 +185,9 @@ type VhostUserDeviceAttrs struct {
 
 	// MacAddress is only meaningful for vhost user net device
 	MacAddress string
+
+	// These are only meaningful for vhost user fs devices
+	Tag string
 }
 
 // GetHostPathFunc is function pointer used to mock GetHostPath in tests.

virtcontainers/device/drivers/vhost_user_fs.go

@@ -0,0 +1,65 @@
+// Copyright (C) 2019 Red Hat, Inc.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+package drivers
+
+import (
+	"encoding/hex"
+
+	"github.com/kata-containers/runtime/virtcontainers/device/api"
+	"github.com/kata-containers/runtime/virtcontainers/device/config"
+	"github.com/kata-containers/runtime/virtcontainers/utils"
+)
+
+// VhostUserFSDevice is a virtio-fs vhost-user device
+type VhostUserFSDevice struct {
+	*GenericDevice
+	config.VhostUserDeviceAttrs
+}
+
+// Device interface
+
+func (device *VhostUserFSDevice) Attach(devReceiver api.DeviceReceiver) (err error) {
+	skip, err := device.bumpAttachCount(true)
+	if err != nil {
+		return err
+	}
+	if skip {
+		return nil
+	}
+
+	defer func() {
+		if err != nil {
+			device.bumpAttachCount(false)
+		}
+	}()
+
+	// generate a unique ID to be used for hypervisor commandline fields
+	randBytes, err := utils.GenerateRandomBytes(8)
+	if err != nil {
+		return err
+	}
+	id := hex.EncodeToString(randBytes)
+
+	device.DevID = id
+	device.Type = device.DeviceType()
+
+	return devReceiver.AppendDevice(device)
+}
+
+func (device *VhostUserFSDevice) Detach(devReceiver api.DeviceReceiver) error {
+	_, err := device.bumpAttachCount(false)
+	return err
+}
+
+func (device *VhostUserFSDevice) DeviceType() config.DeviceType {
+	return config.VhostUserFS
+}
+
+// GetDeviceInfo returns device information that the device is created based on
+func (device *VhostUserFSDevice) GetDeviceInfo() interface{} {
+	device.Type = device.DeviceType()
+	return &device.VhostUserDeviceAttrs
+}