USB devices with same vendor:product id

[Ján Tomko]

On Mon, Feb 03, 2020 at 02:20:47PM +0100, Maxime Accadia wrote:
>Hi,
>
>We have a VM with several USB devices attached. Everything works well, but sometimes, after a reboot of the host, some usb device get a different bus/device number and that prevent the reboot of the VM :
>
>-------
>error: Failed to start domain xxx
>error: internal error: Did not find USB device 04b9:0300 bus:1 device:5
>-------
>
>I guess this is because we have multiple usb devices with the same vendor/product ID :
>
>-------
>    <hostdev mode='subsystem' type='usb' managed='yes'>
>      <source>
>        <vendor id='0x04b9'/>
>        <product id='0x0300'/>
>        <address bus='2' device='4'/>
>      </source>
>      <alias name='hostdev0'/>
>      <address type='usb' bus='0' port='2'/>
>    </hostdev>
>    <hostdev mode='subsystem' type='usb' managed='yes'>
>      <source>
>        <vendor id='0x0529'/>
>        <product id='0x0001'/>
>        <address bus='1' device='7'/>
>      </source>
>      <alias name='hostdev1'/>
>      <address type='usb' bus='0' port='1.2'/>
>    </hostdev>
>    <hostdev mode='subsystem' type='usb' managed='yes'>
>      <source>
>        <vendor id='0x0529'/>
>        <product id='0x0001'/>
>        <address bus='2' device='3'/>
>      </source>
>      <alias name='hostdev2'/>
>      <address type='usb' bus='0' port='1.4'/>
>    </hostdev>
>    <hostdev mode='subsystem' type='usb' managed='yes'>
>      <source>
>        <vendor id='0x04b9'/>
>        <product id='0x0300'/>
>        <address bus='1' device='6'/>
>      </source>
>      <alias name='hostdev3'/>
>      <address type='usb' bus='0' port='1.1'/>
>    </hostdev>
>-------
>
>Any idea on how to handle this case ?
>
>We were thinking about using udev, but it seems that libvirt only supports vendor/id (not unique in our case) and bus/device (not predictable) to identify usb devices.

There has been a proposal (or two?) for addressing USB hostdevs by bus/port
https://bugzilla.redhat.com/show_bug.cgi?id=1497984
Sadly it never landed upstream.

Other than writing a custom script that fills in the <address bus='1'
device='6'/> XML with the current values, I can't think of any solution.

Jano

>
>Thanks,
>
>Maxime Accadia
>
>P.S. We use libvirt 4.0.0 on Ubuntu 18.04
>
>
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