Re: [PATCH v3 2/3] KVM: MMU: fix accessed bit set on prefault path

Gleb Natapov
2010-11-30T17:50:11Z

On Wed, Dec 01, 2010 at 12:52:22AM +0800, Xiao Guangrong wrote:
> On 11/30/2010 09:29 PM, Gleb Natapov wrote:
>
> >> + if (!shadow_accessed_mask)
> >> + return;
> >> +
> > I don't get this. As far as I can see VMX inits shadow_accessed_mask to
> > be zero if ept is enabled. This line here means that we never prefault with ept
> > enabled. It is opposite from what it should be.
> >
>
> Since it's no accessed bit on EPT, it's no way to distinguish between actually
> accessed translations and prefault.
Why is this a problem? We do what this page to not be evicted again
since we expect it to be accessed.

--
Gleb.