for all those who are running Ryzen 3rd Gen processors and using VM's, there seems to be a bug in Qemu 5.0 where in windows enters a BSOD with an error message KERNEL_SECURITY_FAILURE.
Here is a link to the discussion on reddit:
https://www.reddit.com/r/VFIO/comments/gf53o8/upgrading_to_qemu_5_broke_my_setup_windows_bsods/
The following MUST be added to the VM xml file to allow windows to successfully boot.
<qemu:commandline>
<qemu:arg value='-cpu'/>
<qemu:arg value='host,topoext=on,invtsc=on,hv-time,hv-relaxed,hv-vapic,hv-spinlocks=0x1fff,hv-vpindex,hv-synic,hv-stimer,hv-reset,hv-frequencies,host-cache-info=on,l3-cache=off,-amd-stibp'/>
</qemu:commandline>