(In reply to Luke A. Guest from comment #22)
> I'd like to report a minor success. I've managed to boot into win8.1 twice
> in a row. I booted as normal through virt-manager, then shutdown from inside
> the guest, then called a script:

Hi Luke, few questions. When booting the host, do you boot with amdgpu or
vfio-pci bound to the GPU? After you've started a VM, did you bind back to
amdgpu or did you stay on vfio-pci?

Is it during vfio or amdgpu control that your system hangs on the second boot?

If it's during amdgpu, have you tried my patch from comment 20?