I have the following USB devices on a Linux server:

# lsusb -t
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=hub, Driver=hub/6p, 480M
        |__ Port 2: Dev 3, If 0, Class=HID, Driver=usbfs, 1.5M
        |__ Port 3: Dev 4, If 0, Class=hub, Driver=hub/4p, 480M
            |__ Port 1: Dev 8, If 0, Class=print, Driver=usbfs, 12M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=hub, Driver=hub/6p, 480M

I would like to pass the entire USB hub (Dev 4) to a Windows XP guest. In this a device attached and removed to the hub should be automatically handled by the guest (right?).

I tried the following code with virsh attach-device:

<hostdev mode='subsystem' type='usb' managed='yes'>
  <address type='usb' bus='0x002' port='1.3' />

but it didn't work:

error: Failed to attach device from attach_hub.xml
error: internal error usb address needs device id

What am I doing wrong?

  • What about my solution on your other post ? I told you to try specifying a different controller device in the configuration file, did you try it?
    – user186340
    Feb 13, 2015 at 16:49
  • Hi @AndréDaniel I cannot operate on the server this week because they are printing a lot of stuff. I'll certainly try your suggestion. I was wondering if there is a way to do it directly, without passing arguments to qemu.
    – stenio
    Feb 13, 2015 at 16:57
  • Actually I just re-read your question carefully and you've tried exactly what I was writing... it may just not be possible to passthrough a hub, but next time you can work on that server try using this same <address></address> syntax to target the printer and see if that helps.
    – user186340
    Feb 13, 2015 at 17:04
  • @AndréDaniel I just tried to with <address type='usb' bus='0x002' port='1.3.1' /> but I get the same error: error: internal error usb address needs device id.
    – stenio
    Feb 20, 2015 at 9:36

3 Answers 3


xml for hub: https://libvirt.org/formatdomain.html#elementsHub

An example:

  <hub type='usb'>
     <address type='usb' bus='0' port='1'/>



I know this thread is a few years old, but I've been doing a few days worth of work on this exact topic and feel the question could use some of my answers.

First, per the Libvirt domain format documentation, the following snippet outlines the correct <hostdev> syntax:

  <hostdev mode='subsystem' type='usb'>
    <source startupPolicy='optional'>
      <vendor id='0x1234'/>
      <product id='0xbeef'/>
    <boot order='2'/>

The reason for your error is due to the missing <vendor> and <product> tags for your USB <source>

Second, If you are running Ubuntu 16.04 or greater (like me), then you will have successful USB passthrough messages with the above XML device format when using the virsh attach-device hot-plug, but the device will never attach to the VM. This is the fault of AppArmor. I found a comment in another thread linking to this AppArmor Libvirt configuration to resolve USB passthrough issues, which I can confirm worked to resolve my issues.

The relevant AppArmor snippet:

In order for a software program to access the usb device correctly the apparmor abstraction for qemu must be changed. Edit /etc/apparmor.d/abstractions/libvirt-qemu add a line:

# this lets qemu read all USB device information and might be considered a security risk
/run/udev/data/* r,

Third, the "USB hubs" referenced in the other answers are not hubs in the scope of the host machine, but rather in the scope of the VM. From the same Libvirt doc:

The hub element has an optional sub-element with type='usb' which can tie the device to a particular controller[...]

Many devices have an optional sub-element to describe where the device is placed on the virtual bus presented to the guest.

Hope this helps somebody :)


If anyone is still looking for that, use the form:

<address type='usb' bus='0' device='1'/>

The device entry corresponds to the "Dev" entry output by lsusb -t

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