linux-kernel - Re: [PATCH] x86/mce/AMD: Fix partial SMCA bank init when CPU 0 != thread 0

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Date:   Thu, 29 Jun 2017 11:22:35 -0500
From:   Jack Miller <jack@...ezen.org>
To:     "Ghannam, Yazen" <Yazen.Ghannam@....com>
Cc:     Jack Miller <jack@...ezen.org>, Borislav Petkov <bp@...e.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH] x86/mce/AMD: Fix partial SMCA bank init when CPU 0 !=
 thread 0

On Wed, Jun 28, 2017 at 1:58 PM, Ghannam, Yazen <Yazen.Ghannam@....com> wrote:
>> With my patch applied, I see entries like l3_cache under hardware thread 0's
>> directory (it's shifted to CPU 1, so machinecheck1).
>> Without my patch, only machinecheck0 has anything interesting in it
>> (insn_fetch, l2_cache etc.) because the init failed on CPU 1.
>>
>
> What happens with SMT off?

I haven't been able to test with SMT off (since it's apparent that
'nosmt' doesn't really do anything and I don't locally have a firmware
option to turn it off).

First things first though, like Boris I'd like to know if there's a
better way to detect this master thread, other than by APIC ID. Right
now I'm working on a v2 that will remove the CPU check, let each one
perform the rdmsr and only update empty bank info. I believe this call
is being serialized elsewhere (need to check), but if I could keep
this patch to a one-liner by detecting the right thread, I'd like to.

Jack