Redirect USB device in KVM while guest is running

Question

I have two USB Redirector devices in my KVM, created using virt-manager:

<redirdev bus="usb" type="spicevmc">
  <alias name="redir0"/>
  <address type="usb" bus="0" port="2"/>
</redirdev>
<redirdev bus="usb" type="spicevmc">
  <alias name="redir1"/>
  <address type="usb" bus="0" port="5"/>
</redirdev>

I can use these to redirect a USB device at runtime, in virt-manager by going to Virtual Machine > Redirect USB device, I can then pick which host devices to pass through the Spice channel:

How do I do the same with virsh, or some other terminal tool? I would like to be able to switch it off and on, basically to move a device from one VM to another.

Answer 1

Turns out, you can do it.

The way it works for me: identify vendor and product IDs. You can see those in the "Select USB devices for redirection" or using lsusb. For me, for SteelSeries Arctis 7, vendor is 1038 and product is 12ad.

Create an XML file with the following contents, in my example I saved it as usb.xml:

   <hostdev mode='subsystem' type='usb' managed='yes'>
      <source>
        <vendor id='0x1038'/>
        <product id='0x12ad'/>
      </source>
    </hostdev>

Now attach it using virsh by using:

$ virsh attach-device <VMName> --file usb.xml --current

--current makes it hotplug the device while the VM is running. Unfortunately it doesn't show up in the Redirect window as connected, because it's not using a Spice channel, but it works nonetheless.

Detach with detach-device.