[SOLVED] Windows Guest Boot Hangs after Enabling Hyper-V in Windows Guest on 13th Gen Intel CPU


New Member
May 11, 2022
Hi, I have been banging my head against the wall trying to get a working configuration for enabling Hyper-V on a 13700K intel host.

I've referenced various CPU flags & kernel versions (5.15-6.2) to try as well as Windows 10/11/Server2019/Server2022 as OS options with no joy so far. With any configuration I use the boot hangs after enabling Hyper-V on the guest.

What are the best practices when trying a setup like this? I used a 10700K as a proof of concept of this idea an was able to enable Hyper-V and utilize GPU-P to split a passed through NVIDIA GPU across the guest and nested guest within. Now on 13th gen I do not get the same result with the same VM details and BIOS options.

I only need to pass the whole GPU via VFIO and don't have issues with code 43 on the guest, so I am just trying to get nested virtualization to work on a Windows guest with hyper-v. How can I troubleshoot why the guest hangs on the boot logo in console?

Thanks! And please let me know if I can provide any more info!
As a follow up, I was able to get this to work on the 13700k intel host with the following arguments in the vm conf file:

args: -cpu SandyBridge,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time,+vmx
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Sorry for the necroposting, but I looked so hard to find a solution to this problem affecting also 12th gen that I really want to thank @brewdamaster and confirm it's working.

Performance hit anyway is huge (near 45%).
Here a Geekbench 6 comparison between host and SandyBridge options:

Using a more recent CPU model and enabling all the 12th gen supported features like below
args: -cpu Cascadelake-Server-noTSX,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time,+vmx,+pdpe1gb,+md-clear,+mds-no,+taa-no,+tsx-ctrl,+spec-ctrl,+stibp,+ssbd,+pcid

mitigate the performance hit (near 10%):
Thanks @fakezeta ! I was able to get almost double single core score on 13700k with your flags. Not quite as improved on the multicore score (about 30% improved) but still a nice performance bump!
I'm experimenting with other CPU model.
The most recent I could get working was Icelake-Server-v4 and performance are near "host" with HVCI off:
args: -cpu Icelake-Server-v4,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time,+vmx,+pdpe1gb,+md-clear,+mds-no,+taa-no,+tsx-ctrl,+spec-ctrl,+stibp,+ssbd,+pcid

Performance with HVCI on are instead reduced of 30% but I think that we must live with performance impact on nested virtualization. :)
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