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

Alex Williamson
2014-06-02T19:18:38Z

On Mon, 2014-06-02 at 15:03 -0400, Bandan Das wrote:
> Michael Tokarev <mjt@tls.msk.ru> writes:
>
> > 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.
>
> Couldn't the arms race be a little less explicit if the commit message
> is changed :) ? Why mention Nvidia at all ? Just state that the intended
> application is for cases where the user might still want to run a piece
> of software that bails out when KVM is detected.

Would we be helping our users by omitting that from the commitlog
though? Thanks,

Alex