KVM/qemu USB pass-through not working for Win7 guest

[Patrick Oltmann]

Hy there

I'm running a KVM/qemu virtual machine with Win7 as a guest and need a USB 
device (Smartcard reader w/ PIN pad) to be passed through into that virtual 
machine. Therefore I use the "-device usb-host, hostbus=X, hostaddr=Y, 
id=hostdev0" command line parameter. However, the device does not show up in 
the Win7 guest, but does appear when do the same with a Linux guest system 
(which doesn't make much sense to me since KVM should be a full-virtualized 
system). Any ideas on how to solve this?

The host system is a Xeon W3680 running F15 64-bit:
kernel.x86_64 (2.6.38.6-27.fc15)
qemu.x86_64 (0.14.0-7.fc15)
libvirt.x86_64 (0.8.8-4.fc15)
virt-manager.noarch (0.8.7-4.fc15)

Thanks in advance!

Patrick