> -----Original Message-----
> From: Benjamin Herrenschmidt [mailto:[email protected]]
> Sent: Thursday, July 05, 2012 1:26 AM
> To: Alexander Graf
> Cc: Caraman Mihai Claudiu-B02008; <[email protected]>; KVM list;
> linuxppc-dev; [email protected] List
> Subject: Re: [Qemu-ppc] [RFC PATCH 12/17] PowerPC: booke64: Add DO_KVM
> kernel hooks
>
> On Wed, 2012-07-04 at 16:29 +0200, Alexander Graf wrote:
>
> > > +#ifdef CONFIG_KVM_BOOKE_HV
> > > +#define KVM_BOOKE_HV_MFSPR(reg, spr) \
> > > + BEGIN_FTR_SECTION \
> > > + mfspr reg, spr; \
> > > + END_FTR_SECTION_IFSET(CPU_FTR_EMB_HV)
> > > +#else
> > > +#define KVM_BOOKE_HV_MFSPR(reg, spr)
> > > +#endif
> >
> > Bleks - this is ugly. Do we really need to open-code the #ifdef here?
> > Can't the feature section code determine that the feature is disabled
> > and just always not include the code?
>
> You can't but in any case I don't see the point of the conditional here,
> we'll eventually have to load srr1 no ? We can move the load up to here
> in all cases or can't we ?
I like the idea, but there is a problem with addition macros which may clobber
r11 and PROLOG_ADDITION_MASKABLE_GEN is such a case.
> If really not, we could have it inside DO_KVM and be done with it no ?
32-bit exception prolog loads srr1 unconditionally, as Alex and Scott mentioned
earlier, so we will be suboptimal for this case.
-Mike
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