Open KVM monitor for your KVM machine in Proxmox GUI or in the command line with the following command:
# qm monitor 168 Entering Qemu Monitor for VM 168 - type 'help' for help qm>
Show the usb devices info from your host machine:
qm> info usbhost Bus 4, Addr 2, Port 1, Speed 12 Mb/s Class 00: USB device 046b:ff10, Virtual Keyboard and Mouse Bus 6, Addr 2, Port 2, Speed 1.5 Mb/s Class 00: USB device 0624:0294, Dell 03R874 Bus 2, Addr 3, Port 1, Speed 480 Mb/s Class 00: USB device 0930:6533, DataTraveler 2.0 Auto filters: Bus *, Addr *, Port *, ID 0930:6533
According to device “USB device 0930:6533” in the example, add the device to guest machine:
qm> device_add usb-host,id=myusb,vendorid=0x0930,productid=0x6533
Verify that the new usb device is added in your guest:
qm> info usb Device 0.1, Port 1, Speed 12 Mb/s, Product QEMU USB Tablet Device 0.3, Port 2, Speed 12 Mb/s, Product QEMU USB Hub Device 0.4, Port 2.1, Speed 480 Mb/s, Product DataTraveler 2.0
After using it, remove usb device from your guest:
qm> device_del myusb
If you run the command again, you will see the usb device is gone from your guest:
qm> info usb Device 0.1, Port 1, Speed 12 Mb/s, Product QEMU USB Tablet Device 0.3, Port 2, Speed 12 Mb/s, Product QEMU USB Hub
This has been tested in Proxmox 3.0/957f0862