Re: [PATCH 2/4 v3] x86: AMD: Add hardware-enforced cache coherency as a CPUID feature

[Krish Sadhukhan]

On 9/11/20 12:36 PM, Dave Hansen wrote:
> On 9/11/20 12:25 PM, Krish Sadhukhan wrote:
> > diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> > index 81335e6fe47d..0e5b27ee5931 100644
> > --- a/arch/x86/include/asm/cpufeatures.h
> > +++ b/arch/x86/include/asm/cpufeatures.h
> > @@ -293,6 +293,7 @@
> >   #define X86_FEATURE_FENCE_SWAPGS_USER	(11*32+ 4) /* "" LFENCE in user entry SWAPGS path */
> >   #define X86_FEATURE_FENCE_SWAPGS_KERNEL	(11*32+ 5) /* "" LFENCE in kernel entry SWAPGS path */
> >   #define X86_FEATURE_SPLIT_LOCK_DETECT	(11*32+ 6) /* #AC for split lock */
> > +#define X86_FEATURE_HW_CACHE_COHERENCY (11*32+ 7) /* AMD hardware-enforced cache coherency */
> That's an awfully generic name.  We generally have "hardware-enforced
> cache coherency" already everywhere. :)
>
> This probably needs to say something about encryption, or even SEV
> specifically.


How about X86_FEATURE_ENC_CACHE_COHERENCY ?

> I also don't see this bit in the "AMD64 Architecture
> Programmer’s Manual".  Did I look in the wrong spot somehow?
Section 7.10.6 in APM mentions this.