Re: [tip:x86/urgent] x86, AMD: Disable wrongly setX86_FEATURE_LAHF_LM CPUID bit

From: Borislav Petkov
Date: Sun Aug 30 2009 - 07:44:08 EST

On Mon, Aug 24, 2009 at 11:44:30PM -0700, H. Peter Anvin wrote:
> On 08/24/2009 10:52 PM, Borislav Petkov wrote:
> > On Mon, Aug 24, 2009 at 01:34:07PM -0700, H. Peter Anvin wrote:
> >> Looks reasonable... although part of me wonders if having a pointer to
> >> an array containing the entire register file in and out is even better,
> >> of if I'm just overengineering at this point.
> >
> > Hmm, let's have necessity determine that. I can only think of %edi being
> > used as an input reg to rd/wrmsr beside %ecx but it could be very well
> > that some other x86 hardware uses other regs too. Do we actually need
> > all regs or a two should suffice?
> >
> Hard to know. In theory we shouldn't need ESI and EDI either!
> As I said, I wouldn't have worried about it at all if it wasn't for
> paravirt_ops turning these things into ABIs.

Ok, here's what I could come up with. It seems to work (tested only on a
Fam10h box), it should cover all our msr needs for now and alleviate the
need for adding yet another paravirt_ops member.

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