linux-kernel - Re: [patch V6a 01/19] x86/cpu: Provide cpuid

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Date: Thu, 15 Feb 2024 10:49:02 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: LKML <linux-kernel@...r.kernel.org>, x86@...nel.org, 
	Tom Lendacky <thomas.lendacky@....com>, Andrew Cooper <andrew.cooper3@...rix.com>, 
	Arjan van de Ven <arjan@...ux.intel.com>, Huang Rui <ray.huang@....com>, 
	Juergen Gross <jgross@...e.com>, Dimitri Sivanich <dimitri.sivanich@....com>, 
	Sohil Mehta <sohil.mehta@...el.com>, K Prateek Nayak <kprateek.nayak@....com>, 
	Kan Liang <kan.liang@...ux.intel.com>, Zhang Rui <rui.zhang@...el.com>, 
	"Paul E. McKenney" <paulmck@...nel.org>, Feng Tang <feng.tang@...el.com>, 
	Andy Shevchenko <andy@...radead.org>, Michael Kelley <mhklinux@...look.com>, 
	"Peter Zijlstra (Intel)" <peterz@...radead.org>, Wang Wendy <wendy.wang@...el.com>
Subject: Re: [patch V6a 01/19] x86/cpu: Provide cpuid_read() et al.

On Wed, Feb 14, 2024 at 10:29 PM Thomas Gleixner <tglx@...utronix.de> wrote:
>
> Provide a few helper functions to read CPUID leafs or individual registers
> into a data structure without requiring unions.

..

> +#define cpuid_subleaf(leaf, subleaf, regs) {           \
> +       BUILD_BUG_ON(sizeof(*(regs)) != 16);            \
> +       __cpuid_read(leaf, subleaf, (u32 *)(regs));     \
> +}
> +
> +#define cpuid_leaf(leaf, regs) {                       \
> +       BUILD_BUG_ON(sizeof(*(regs)) != 16);            \
> +       __cpuid_read(leaf, 0, (u32 *)(regs));           \
> +}

..

> +#define cpuid_subleaf_reg(leaf, subleaf, regidx, reg) {                \
> +       BUILD_BUG_ON(sizeof(*(reg)) != 4);                      \
> +       __cpuid_read_reg(leaf, subleaf, regidx, (u32 *)(reg));  \
> +}
> +
> +#define cpuid_leaf_reg(leaf, regidx, reg) {                    \
> +       BUILD_BUG_ON(sizeof(*(reg)) != 4);                      \
> +       __cpuid_read_reg(leaf, 0, regidx, (u32 *)(reg));        \
> +}

I'm wondering if we can use static_assert() instead of BUILD_BUG_ON()
in the above macros.

-- 
With Best Regards,
Andy Shevchenko