linux-kernel - Re: [PATCH v2 1/2] x86/AMD: Fix cpu_llc

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Date:   Mon, 31 Oct 2016 15:15:44 -0400
From:   Yazen Ghannam <yazen.ghannam@....com>
To:     Borislav Petkov <bp@...e.de>
CC:     <linux-kernel@...r.kernel.org>, <x86@...nel.org>,
        <stable@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] x86/AMD: Fix cpu_llc_id for AMD Fam17h systems

> > The current Fam17h cpu_llc_id  derivation has an underflow bug when
> 				^
> 			(Last Level Cache ID)
> 
> Let's write it out the first time.
> 

Ack.

> > 
> > The apicid decoding is fixed for bits 3 and above,
> 						    ^
> "is fixed ... in register... "
> 

Ack.

> > which give the core
> > complex, node and socket IDs. The LLC is at the core complex level so we
> > can find a unique cpu_llc_id by right shifting the apicid by 3.
> 
> "... because then the LSBit will be the Core Complex ID."
> 

Ack.

> > We can fix the underflow bug and simplify the code by replacing the
> > current cpu_llc_id derivation with a right shift.
> > 
> > Signed-off-by: Yazen Ghannam <Yazen.Ghannam@....com>
> > Cc: <stable@...r.kernel.org> # v4.4..
> > Fixes: 3849e91f571d ("x86/AMD: Fix last level cache topology for AMD Fam17h systems")
> > ---
> 
> I'll run it soon.
>

Thanks,
Yazen