Re: [PATCH] KVM: MMU: Do not unconditionally read PDPTE from guest memory

["Roedel, Joerg" <Joerg.Roedel@amd.com>]

On Sun, Jul 31, 2011 at 04:08:44AM -0400, Avi Kivity wrote:
> On 07/29/2011 02:31 PM, Roedel, Joerg wrote:
> > On Thu, Jul 28, 2011 at 04:36:17AM -0400, Avi Kivity wrote:
> > >  Architecturally, PDPTEs are cached in the PDPTRs when CR3 is reloaded.
> > >  On SVM, it is not possible to implement this, but on VMX this is possible
> > >  and was indeed implemented until nested SVM changed this to unconditionally
> > >  read PDPTEs dynamically.  This has noticable impact when running PAE guests.
> > >
> > >  Fix by changing the MMU to read PDPTRs from the cache, falling back to
> > >  reading from memory for the nested MMU.
> > >
> > >  Signed-off-by: Avi Kivity<avi@redhat.com>
> >
> > Hmm, interesting. Sorry for breaking it. I tested the patch on nested
> > svm, it works fine.
> 
> Does pae-on-pae work for you?

Only tested pae-on-longmode. I'll see if I can find my 32bit
installation again and test this too.

	Joerg

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