[vfio-users] AMD + Nvidia + WIn 8.1 + hv_vendor_id + QEMU GIT == hang on boot

[Aaron Campbell]

> On Nov 7, 2015, at 8:44 PM, David Sutton <kantras at gmail.com> wrote:
> 
> All,
> 
>   After watching the list and seeing the hv_vendor_id patch, I decided to try and see if it would help with my setup; This system is running Arch ( linux-lts 4.1.12 kernel ) on an AMD FX-8350, an Nvidia 780 being passed through to a Windows 8.1 Pro guest. 
> 
>   I installed the qemu-git package, created a wrapper script to update the options "host,kvm=off,hv_time,hv_relaxed,hv_vapic,hv_spinlocks=0x1fff,hv_vendor_id=vendor" and tried to boot. It passed through the OVMF boot screen to the Windows loading screen, and then seems to hang (dots stop rotating) with 100% CPU usage showing under VMM.


Our h/w is different (Intel Haswell, GTX 970 here), but when I had this problem with qemu 2.4 and Win 8.1, a kernel downgrade to 4.0.4-301.fc22 (Fedora) fixed it.  Prior to this I had tried 4.1.6-200.fc22, 4.2.3-300.fc22, and 4.3.0 final (released just a week or so ago), and all hung in this way (dots stop rotating).  Unfortunately I haven’t had time to bisect or narrow down the exact kernel release where this regressed., but apparently it was somewhere between 4.0.4 and 4.1.6.  So I have been stuck on 4.0.4 since.

Is anyone aware of any suspect or problematic KVM changes to the kernel between these releases that I may look into?

-Aaron