How to use ehci usb controller on kvm?

[li li]

Hello guys,

I need to transmit a USB3.0 device to guest VM.

The VM created by cloudstack uses the piix3-uhci controller, so it is 
impossible to identify USB 2.0 or USB3.0 devices in the guest vm.

Is there any way to add EHCI controller to VM by default?


for example


<controller type='usb' index='0' model='piix3-uhci'>
<controller type='usb'index='1' model='ehci'/>