linux-kernel - RE: [PATCH v4 24/71] perf/x86/msr: Switch to new Intel CPU model defines

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Date: Thu, 25 Apr 2024 16:54:37 +0000
From: "Luck, Tony" <tony.luck@...el.com>
To: "Hansen, Dave" <dave.hansen@...el.com>, Borislav Petkov <bp@...en8.de>,
	Thomas Gleixner <tglx@...utronix.de>, Dave Hansen
	<dave.hansen@...ux.intel.com>, "x86@...nel.org" <x86@...nel.org>
CC: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim
	<namhyung@...nel.org>, Mark Rutland <mark.rutland@....com>, "Alexander
 Shishkin" <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>, "Hunter, Adrian" <adrian.hunter@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>, "linux-perf-users@...r.kernel.org"
	<linux-perf-users@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "patches@...ts.linux.dev"
	<patches@...ts.linux.dev>
Subject: RE: [PATCH v4 24/71] perf/x86/msr: Switch to new Intel CPU model
 defines

> Well, my point is that a .x86_vfm switch:
>
>> +	switch (boot_cpu_data.x86_vfm) {
>> +	case INTEL_NEHALEM:
>> +	case INTEL_NEHALEM_G:
>
> implicitly checks boot_cpu_data.x86==6.  So the explicit check can now
> go away, no matter what CPUs are being checked.

Implicitly checks vendor too. So the whole:

        if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL ||
            boot_cpu_data.x86 != 6)
                return false;

can go away (assuming this isn't used in some performance critical path
where the quick return would make some difference for AMD.

-Tony