Core2Duo and KVM may not boot Win8 properly on 3.x kernels

When I start up QEMU w/ KVM 1.7.0 on a Core2Duo machine running a vanilla kernel
3.4.67 or 3.10.12 to run a Windows 8.0 guest, the guest freezes at Windows 8 boot without any error.
When I dump the CPU registers via "info registers", nothing changes, that means
the system really stalled. Same happens with QEMU 2.0.0 and QEMU 2.1.0.

But - when I run the very same guest using Kernel 2.6.32.12 and QEMU 1.7.0 or 2.0.0 on
the host side it works on the Core2Duo. Also the system above but just with an
i3 or i5 CPU it works fine.

I already disabled networking and USB for the guest and changed the graphics
card - no effect. I assume that some mean bits and bytes have to be set up
properly to get the thing running.

Seems to be related to a kvm/progressor incompatibility.