Re: [PATCH] KVM: SVM: Keep intercepting task switching with NPT enabled

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

On Tue, Oct 18, 2011 at 01:37:32PM -0400, Avi Kivity wrote:
> On 10/18/2011 06:35 PM, Roedel, Joerg wrote:
> > On Tue, Oct 18, 2011 at 12:23:11PM -0400, Jan Kiszka wrote:
> > > AMD processors apparently have a bug in the hardware task switching
> > > support when NPT is enabled. If the task switch triggers a NPF, we can
> > > get wrong EXITINTINFO along with that fault. On resume, spurious
> > > exceptions may then be injected into the guest.
> > > 
> > > We were able to reproduce this bug when our guest triggered #SS and the
> > > handler were supposed to run over a separate task with not yet touched
> > > stack pages.
> > > 
> > > Work around the issue by continuing to emulate task switches even in
> > > NPT mode.
> > > 
> > > Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> >
> > Acked-by: Joerg Roedel <joerg.roedel@amd.com>
> >
> 
> Will there be an erratum published for this bug?  Are all processors
> affected?

For now this behavior should be expected on all NPT capable processors.

> I'd like to limit this to just the buggy processors, if and when fixed
> processors become available.

I don't know this yet, but I'll try to find out.

Thanks,

	Joerg

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