virt-usb

#!/usr/bin/env python
import argparse
import contextlib
import libvirt
import sys


template = r'''
<hostdev mode='subsystem' type='usb'>
    <source>
        <vendor id='0x%04x'/>
        <product id='0x%04x'/>
    </source>
</hostdev>
'''.strip()


@contextlib.contextmanager
def libvirt_open(uri):
    conn = libvirt.open(uri)
    try:
        yield conn
    finally:
        conn.close()


if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='USB passthrough helper')
    parser.add_argument('-c', metavar='URI', default='qemu:///system',
                        help='URI to connect to')
    parser.add_argument('--domain', required=True,
                        help='libvirt domain to attach device to')
    parser.add_argument('--devices', metavar='VendorID:ProductID', nargs='+',
                        required=True, help='USB devices to passthrough')

    group = parser.add_mutually_exclusive_group(required=True)
    group.add_argument('--attach', action='store_true',
                       help='attach the devices to guest')
    group.add_argument('--detach', action='store_false',
                       help='detach the devices from guest')
    args = parser.parse_args()

    try:
        with libvirt_open(args.c) as conn:
            domain = conn.lookupByName(args.domain)

            for device in args.devices:
                device = tuple(map(lambda x: int(x, 16), device.split(':')))

                if args.attach:
                    domain.attachDevice(template % device)
                else:
                    domain.detachDevice(template % device)
    except (libvirt.libvirtError) as e:
        print(e)
        sys.exit(1)