Bug in usbdevices option handling when BusID=8

[Gordan Bobic <gordan@bobich.net>]

Configuration: Xen 4.3.0, xl

I have been trying to pass USB mouse and keyboard through do a domU 
using usbdevices = [] option. The success/failure seems to be related to 
the bus.device option.

Specifically, in quemu log:

husb: open device 0.2
/dev/bus/usb/000/002: No such file or directory
Warning: could not add USB device host:008.002
husb: open device 6.2
husb: config #1 need -1
husb: 2 interfaces claimed for configuration 1
husb: grabbed usb device 6.2

In domU config:
usbdevice = [ 'host:008.002', 'host:006.002' ]

At a glance, this looks like something buggy happens when BusID=8. It 
sees that the device is host:008.002, but then goes and tries to open 
/dev/bus/usb/000/002 instead of /dev/bus/usb/008/002.

If I change the port where the device is connected and it gets a 
different ID, and I change the config to:

usbdevice = [ 'host:003.002', 'host:006.002' ]

the log then says:

husb: open device 3.2
husb: config #1 need -1
husb: 1 interfaces claimed for configuration 1
husb: grabbed usb device 3.2
husb: open device 6.2
husb: config #1 need -1
husb: 2 interfaces claimed for configuration 1
husb: grabbed usb device 6.2

and both devices are availble in domU.

Bug?

Gordan