linux-kernel - Re: [PATCH v1 0/9] x86/cpuid: Headers cleanup

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Message-ID: <aCYbiLjkWM67Ogj_@gmail.com>
Date: Thu, 15 May 2025 18:51:20 +0200
From: Ingo Molnar <mingo@...nel.org>
To: "Ahmed S. Darwish" <darwi@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	John Ogness <john.ogness@...utronix.de>, x86@...nel.org,
	x86-cpuid@...ts.linux.dev, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 0/9] x86/cpuid: Headers cleanup


* Ahmed S. Darwish <darwi@...utronix.de> wrote:

> Hi,
> 
> This is a CPUID headers cleanup series, on top of tip:x86/cpu.  It is a
> precursor for the upcoming v2 of the CPUID parser:
> 
>     [PATCH v1 00/26] x86: Introduce centralized CPUID model
>     https://lore.kernel.org/lkml/20250506050437.10264-1-darwi@linutronix.de
> 
> as suggested by Ingo here:
> 
>     https://lore.kernel.org/lkml/aBnSgu_JyEi8fvog@gmail.com
> 
> * Summary:
> 
> The current CPUID header structure is:
> 
>     include/asm/
>     ├── cpuid
>     │   ├── api.h
>     │   ├── leaf_0x2_api.h
>     │   └── types.h
>     └── cpuid.h
> 
> Simplify it into:
> 
>     include/asm/
>     ├── api.h
>     └── types.h
> 
> Standardize the CPUID header namespace by enforcing a "cpuid_" prefix for
> all exported symbols.  That is:
> 
>     have_cpuid_p()		➤	cpuid_feature()
>     hypervisor_cpuid_base()	➤	cpuid_hypervisor_base()
>     native_cpuid()		➤	cpuid_native()
>     native_cpuid_REG()		➤	cpuid_native_REG()
> 
> Also rename:
> 
>     cpuid_get_leaf_0x2_regs()	➤	cpuid_leaf_0x2()
> 
> for consistency with the other <asm/cpuid/api.h> accessors that return
> full CPUID register output; i.e., cpuid_leaf() and cpuid_subleaf().
> 
> Finally, rename:
> 
>     for_each_leaf_0x2_entry()   ➤	for_each_cpuid_0x2_desc()
> 
> to include "cpuid" in the iterator name, and since what is being iterated
> upon is CPUID(0x2) cache and TLB "descriptos", not "entries".
> 
> * Testing:
> 
> - Basic one-by-one allyesconfig compilation
> 
> - Comparison of a before/after of below files:
> 
>   - /proc/cpuinfo
>   - /sys/devices/system/cpu/
>   - /sys/kernel/debug/x86/topo/
>   - dmesg --notime | grep 'Last level [id]TLB entries'
> 
> Thanks!
> 
> 8<--
> 
> Ahmed S. Darwish (9):
>   x86/cpuid: Move CPUID(0x2) APIs into <cpuid/api.h>
>   x86/cpuid: Set <asm/cpuid/api.h> as the main CPUID header
>   x86/cpuid: Rename have_cpuid_p() to cpuid_feature()
>   x86/cpuid: Rename hypervisor_cpuid_base() to cpuid_hypervisor_base()
>   x86/cpuid: Rename cpuid_get_leaf_0x2_regs() to cpuid_leaf_0x2()
>   x86/cacheinfo: Rename CPUID(0x2) descriptors iterator parameter
>   x86/cpu: Rename CPUID(0x2) descriptors iterator parameter
>   x86/cpuid: Rename native_cpuid() to cpuid_native()
>   x86/cpuid: Rename native_cpuid_REG() to cpuid_native_REG()

Thank you for doing this. I've reviewed the series and applied these:

    x86/cpuid: Move CPUID(0x2) APIs into <cpuid/api.h>
    x86/cpuid: Set <asm/cpuid/api.h> as the main CPUID header
    x86/cpuid: Rename have_cpuid_p() to cpuid_feature()
    x86/cpuid: Rename cpuid_get_leaf_0x2_regs() to cpuid_leaf_0x2()
    x86/cacheinfo: Rename CPUID(0x2) descriptors iterator parameter
    x86/cpu/intel: Rename CPUID(0x2) descriptors iterator parameter

I had some questions about:

    x86/cpuid: Rename hypervisor_cpuid_base() to cpuid_hypervisor_base()
    x86/cpuid: Rename native_cpuid() to cpuid_native()

and you had better ideas about:

    x86/cpuid: Rename native_cpuid_REG() to cpuid_native_REG()

Thanks,

	Ingo