Re: [PATCH] x86, msr: Better document AMD "tweak MSRs", rename MSR_F15H_IC_CFG

From: Borislav Petkov
Date: Tue Apr 25 2017 - 08:59:28 EST


On Tue, Apr 25, 2017 at 02:16:55PM +0200, Denys Vlasenko wrote:
> However, all IBS registers are in this range.

I knew you were gonna say that. But IBS registers are architectural too
in the sense that they are behind a CPUID bit.

> DRi_ADDR_MASK are in this range - and these are very useful, likely to
> stay.

Those are too behind a CPUID bit.

> In the arch/x86/include/asm/msr-index.h file we already have
> three "tweak" MSRs defined with "AMD64":
>
> #define MSR_AMD64_LS_CFG 0xc0011020
> #define MSR_AMD64_DC_CFG 0xc0011022
> #define MSR_AMD64_BU_CFG2 0xc001102a
>
> I just noticed that we have a fourth one in
> arch/x86/kernel/cpu/amd.c:
>
> #define MSR_AMD64_DE_CFG 0xC0011029

That's wrong. I think we should call those something else but not
"AMD64". Perhaps the families for which the workaround is being applied.
In the last case, MSR_F12H_DE_CFG, for example. And yes, I should've
paid attention to that but ...

--
Regards/Gruss,
Boris.

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