linux-kernel - Re: [PATCH v4 2/2] x86/amd: Fixup cpu_core_id for family17h downcore configuration

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Date:   Tue, 25 Jul 2017 07:56:47 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org, tglx@...utronix.de,
        mingo@...hat.com, hpa@...or.com, peterz@...radead.org,
        Yazen.Ghannam@....com, Andreas Herrmann <aherrmann@...e.com>
Subject: Re: [PATCH v4 2/2] x86/amd: Fixup cpu_core_id for family17h downcore
 configuration

On Tue, Jul 25, 2017 at 12:51:53PM +0700, Suravee Suthikulpanit wrote:
> Ok. Sure, it doesn't need be contiguous. But at least the cpu_core_id should
> represent an ID that make some sense since it is used in the
> arch/x86/kernel/smpboot.c: match_smt() and some other places. So, if it's
> invalid for the downcore configuration (i.e. duplicated where it should not
> be), we should at least clean this up.

Ah right, we do use it for the SMT siblings. So yes, it should be
correct for them. And I'm pretty sure the numbers we derive from the
initial APIC ID are already good enough for that.

> I will update the patch to only limit the fixup to pre-family17h.

Yeah, give that a try. Make sure to check the topology masks are
correct.

Thanks.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--