RE: [PATCH v2 10/11] arch/x86: Add AMD feature bit X86_FEATURE_MBA in cpuid bits array

[Moger, Babu]

> -----Original Message-----
> From: Borislav Petkov <bp@xxxxxxxxx>
> Sent: Friday, October 5, 2018 4:31 PM
> To: Moger, Babu <Babu.Moger@xxxxxxx>
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> Subject: Re: [PATCH v2 10/11] arch/x86: Add AMD feature bit
> X86_FEATURE_MBA in cpuid bits array
> 
> On Fri, Oct 05, 2018 at 08:56:09PM +0000, Moger, Babu wrote:
> > From: Sherry Hurwitz <sherry.hurwitz@xxxxxxx>
> >
> > The feature bit X86_FEATURE_MBA is detected via CPUID leaf 0x80000008
> > EBX Bit 06. This bit indicates the support of AMD's MBA feature.
> >
> > This feature is supported by both Intel and AMD. But they are detected
> > different CPUID leaves.
> >
> > Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> > Signed-off-by: Sherry Hurwitz <sherry.hurwitz@xxxxxxx>
> 
> This SOB chain should be the other way around - first Sherry, then you.

Sure. Will change it.
> 
> > ---
> >  arch/x86/kernel/cpu/scattered.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/kernel/cpu/scattered.c
> b/arch/x86/kernel/cpu/scattered.c
> > index 772c219b6889..bd7853334b27 100644
> > --- a/arch/x86/kernel/cpu/scattered.c
> > +++ b/arch/x86/kernel/cpu/scattered.c
> > @@ -17,7 +17,11 @@ struct cpuid_bit {
> >  	u32 sub_leaf;
> >  };
> >
> > -/* Please keep the leaf sorted by cpuid_bit.level for faster search. */
> > +/*
> > + * Please keep the leaf sorted by cpuid_bit.level for faster search.
> > + * X86_FEATURE_MBA supported by both Intel and AMD. But the cpuid
> > + * levels are different. Add a separate enty for each.
> > + */
> >  static const struct cpuid_bit cpuid_bits[] = {
> >  	{ X86_FEATURE_APERFMPERF,       CPUID_ECX,  0, 0x00000006, 0 },
> >  	{ X86_FEATURE_EPB,		CPUID_ECX,  3, 0x00000006, 0 },
> > @@ -29,6 +33,7 @@ static const struct cpuid_bit cpuid_bits[] = {
> >  	{ X86_FEATURE_HW_PSTATE,	CPUID_EDX,  7, 0x80000007, 0 },
> >  	{ X86_FEATURE_CPB,		CPUID_EDX,  9, 0x80000007, 0 },
> >  	{ X86_FEATURE_PROC_FEEDBACK,    CPUID_EDX, 11, 0x80000007, 0 },
> > +	{ X86_FEATURE_MBA,		CPUID_EBX,  6, 0x80000008, 0 },
> >  	{ X86_FEATURE_SME,		CPUID_EAX,  0, 0x8000001f, 0 },
> >  	{ X86_FEATURE_SEV,		CPUID_EAX,  1, 0x8000001f, 0 },
> >  	{ 0, 0, 0, 0, 0 }
> > --
> 
> With that fixed:
> 
> Reviewed-by: Borislav Petkov <bp@xxxxxxx>
> 

Thanks

> --
> Regards/Gruss,
>     Boris.
> 
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