[vfio-users] Windows 10 guest refuses to boot when passed my NVIDIA graphics card

[Alex Williamson]

On Tue, Sep 15, 2015 at 3:32 PM, Jasen Borisov <tajjada at gmail.com> wrote:

> I managed to successfully boot Arch Linux in the VM. Turned out I wasn't
> patient enough. With enough waiting, the same VM configuration as before
> (including my passthrough NVIDIA *and* EHCI!) booted. But it is
> *incredibly* slow. Took over 10 minutes to get to a login prompt, and a
> couple of minutes to do its automatic root login. I plugged a USB keyboard
> into the hardware port on my PC that belongs to the EHCI controller I
> passed to the VM, and the keyboard worked as expected and I could type
> inside the VM. I managed to mount a filesystem and dump `dmesg` to a file,
> so I can get it on my desktop. Here is a pastebin of it:
> https://bpaste.net/show/e6970c05aff5
>
> This makes me think that *maybe* if I leave Windows to boot overnight,
> next morning I might be surprised by a desktop :)
>
> Anyway, it is unacceptably slow, and I would appreciate any help to
> improve the situation.
>
> I noticed a lot of errors regarding msrr, both in the host and guest
> dmesg, so I guess it would probably be a good idea to add that KVM option
> you mentioned. However, I doubt that that is the cause of the performance
> problems. When I remove all VFIO devices and replace them with emulated
> ones, Arch Linux is very fast (or rather, normal, just very fast in
> comparison) despite the same msrr errors appearing.
>
> Any ideas?
>

What if you downgrade to kernel 4.1?  The MTRR issue we've been battling
generally resolves itself and the VM runs at full speed once passed
firmware.  I'll see if I can make my box act this poorly.  Running 8 vCPUs
on your system is surely not helping performance, but this sounds like
orders of magnitude worse than that.
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