Hello, I passthrough a host usb device to a guest with a bus number and device number in the xml to identify the usb device. When I unplug and then plug back into the same USB physical port, the guest identifies the usb device failed. Because on the host ,the usb device number increases. So , I want to know that whether Libvirt will provide an interface that identifies a host usb device with bus number and physical port . As far as I know ,Qemu upstream had added a hostport property which allows to specify the host usb with bus number and physical port. the patch is : https://lists.gnu.org/archive/html/qemu-devel/2011-05/msg02341.html Best Regards