linux-kernel - Re: [tip:x86/urgent] x86/cpu: Probe CPUID leaf 6 even when cpuid

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Date:   Tue, 20 Dec 2016 10:27:36 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "H. Peter Anvin" <hpa@...or.com>
cc:     brgerst@...il.com, luto@...nel.org, bp@...en8.de,
        linux-kernel@...r.kernel.org, mingo@...nel.org,
        linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/urgent] x86/cpu: Probe CPUID leaf 6 even when cpuid_level
 == 6

On Mon, 19 Dec 2016, H. Peter Anvin wrote:
> P.S. I would love to (a) move the CPUID bits into a structure instead of
> passing all those crazy pointers around, and (b) stop passing struct
> cpuinfo * around when we only use it for the current processor anyway (a
> lot of these functions are in fact completely invalid if we don't); we
> could define this_cpu_info as (*this_cpu_ptr(&cpu_info)) -- basically
> what I have above -- or directly use percpu functions to access these
> variables.

The whole cpu identify code wants to be rewritten completely. It's full of
conditionals and places which read the same cpuid leaf over and over. The
whole thing is just insane.

The proper solution is to have a single function which reads all available
leafs into a data structure and then do all the conditional computations
and decisions based on that.

Thanks,

	tglx