Re: [RFC PATCH] kvm: Enable -cpu option to hide KVM

Alex Williamson
2014-06-02T18:37:45Z

On Mon, 2014-06-02 at 22:01 +0400, Michael Tokarev wrote:
> 02.06.2014 17:30, Alex Williamson wrote:
> > On Mon, 2014-06-02 at 14:32 +0400, Michael Tokarev wrote:
> >> 01.06.2014 20:25, Alex Williamson wrote:
> >>> The latest Nvidia driver (337.88) specifically checks for KVM as the
> >>> hypervisor and reports Code 43 for the driver in a Windows guest when
> >>> found. Removing or changing the KVM signature is sufficient to allow
> >>> the driver to load.
> >>
> >> Hmm.. Why does it do such thing? Is it in order to prevent the driver
> >> to work in a virtualized windows, ie to prevent vga passthough to work?
> >>
> >> If that's the case, I think it is a lost game. Because they'll be adding
> >> more, cleverer, checks in the next version.
> >
> > Then they'll be pissing off more users and driving them to AMD by doing
> > so. In any case, having the ability to hide the hypervisor seems to
> > stand on it's own. What if we want to test whether a guest behavior is
> > the result of a paravirtual interface? What if a user wants to hide the
> > hypervisor in order to further reduce the exposure surface to the VM?
> > There are reasons beyond an arms race with Nvidia to want a feature like
> > this. Thanks,
>
> You answer as if I were strongly against the change. I'm not.
> What I'm against is about the reasoning. This way you're just
> accepting the arm race.

I'm not sure what you're looking for. Would it be more acceptable if I
don't mention the motivation for adding this feature in the commitlog?
Does it make the feature less worthwhile because it has an immediate
practical application? If we agree that this feature is worthwhile
regardless of the Nvidia situation, how do we add it without
theoretically accepting an arms race? Thanks,

Alex