Re: [PATCH v2 0/4] Enable SMEP CPU Feature

From: Ingo Molnar
Date: Tue May 17 2011 - 07:51:09 EST

* Avi Kivity <avi@xxxxxxxxxx> wrote:

> On 05/17/2011 02:44 PM, Avi Kivity wrote:
> >On 05/17/2011 02:38 PM, Ingo Molnar wrote:
> >>>
> >>> Depends if the guest uses a read-modify-write pattern or not.
> >>We could do it
> >>> transparently in kvm.ko, since the real cr4 need not
> >>corresponds to the guest
> >>> notion (for example, we often set cr0.wp or cr0.ts even
> >>though the guest
> >>> wants them clear).
> >>
> >>Oh, being transparent is a nice touch when it comes to security measures
> >>(catching attackers who think there's no SMEP and such) - but
> >>that would need
> >>KVM support and a new ioctl to configure it, right?
> >
> >Yes.
> >
> btw, KVM support is required anyway, you can't set random bits in
> cr4 (from either the guest or host userspace) - kvm needs to
> understand them.

Sure, that is the whole premise of this discussion.

I meant to say:

"but that would need KVM ABI support via a new ioctl to configure it, right?"


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