Nova/USB device&USB controller

USB device and USB controller Features

Background

Currently, nova has already supported pci-passthrough, but still dosen't support usb-passthrough. In fact usb device is a kind of necessary device in some user scenarios in private cloud.

Use case

1. When i transfer money online, i need a usb-key provided by bank for authentication.

2. When i start a erp software, i need a usb-key provided by software provider for authentication.

3. I need a usb data disk for transferring business data.

Technical verification

1. Test case

   Attach different number of usb devices to different type of usb controllers.

2. Xml definition

   Sample of usb controller:
   <controller type='usb' index='2' model='piix3-uhci'/>
   <controller type='usb' index='1' model='ehci'/>