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From: Thomas Gleixner <tglx@linutronix.de>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>, x86@kernel.org, Tom Lendacky
 <thomas.lendacky@amd.com>, Andrew Cooper <andrew.cooper3@citrix.com>,
 Arjan van de Ven <arjan@linux.intel.com>, Huang Rui <ray.huang@amd.com>,
 Juergen Gross <jgross@suse.com>, Dimitri Sivanich
 <dimitri.sivanich@hpe.com>, Sohil Mehta <sohil.mehta@intel.com>, K Prateek
 Nayak <kprateek.nayak@amd.com>, Kan Liang <kan.liang@linux.intel.com>,
 Zhang Rui <rui.zhang@intel.com>, "Paul E. McKenney" <paulmck@kernel.org>,
 Feng Tang <feng.tang@intel.com>, Andy Shevchenko <andy@infradead.org>,
 Michael Kelley <mhklinux@outlook.com>, "Peter Zijlstra (Intel)"
 <peterz@infradead.org>, Wang Wendy <wendy.wang@intel.com>
Subject: Re: [patch V6a 01/19] x86/cpu: Provide cpuid_read() et al.
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References: <20240212153109.330805450@linutronix.de>
 <20240212153624.516965279@linutronix.de> <878r3mg570.ffs@tglx>
 <CAHp75Vdo7-JqQuZ9ni5a=M3fFM76h4Gr5Babu6hEn0NO-tqpJg@mail.gmail.com>
Date: Thu, 15 Feb 2024 16:07:05 +0100
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On Thu, Feb 15 2024 at 10:49, Andy Shevchenko wrote:

> On Wed, Feb 14, 2024 at 10:29=E2=80=AFPM Thomas Gleixner <tglx@linutronix=
de> wrote:
>>
>> Provide a few helper functions to read CPUID leafs or individual registe=
rs
>> into a data structure without requiring unions.
>
> ...
>
>> +#define cpuid_subleaf(leaf, subleaf, regs) {           \
>> +       BUILD_BUG_ON(sizeof(*(regs)) !=3D 16);            \
>> +       __cpuid_read(leaf, subleaf, (u32 *)(regs));     \
>> +}
>> +
>> +#define cpuid_leaf(leaf, regs) {                       \
>> +       BUILD_BUG_ON(sizeof(*(regs)) !=3D 16);            \
>> +       __cpuid_read(leaf, 0, (u32 *)(regs));           \
>> +}
>
> ...
>
>> +#define cpuid_subleaf_reg(leaf, subleaf, regidx, reg) {                \
>> +       BUILD_BUG_ON(sizeof(*(reg)) !=3D 4);                      \
>> +       __cpuid_read_reg(leaf, subleaf, regidx, (u32 *)(reg));  \
>> +}
>> +
>> +#define cpuid_leaf_reg(leaf, regidx, reg) {                    \
>> +       BUILD_BUG_ON(sizeof(*(reg)) !=3D 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.

Probably.