Re: [PATCH v2 01/29] x86: treewide: Introduce x86_vendor_amd_or_hygon()

[Ingo Molnar <mingo@kernel.org>]

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

> -	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
> -	    boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
> +	if (!x86_vendor_amd_or_hygon(boot_cpu_data.x86_vendor))
>  		return -ENODEV;

Could we just not do this?

The above vendor check may or may not be equivalent X86_FEATURE_ZEN1, 
which we could first assert via a single boot-time check:

	WARN_ON_ONCE(boot_cpu_has(X86_FEATURE_ZEN1) !=
			((boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
			  boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)));

And then replace all the above with the much simpler construct of:

	if (!boot_cpu_has(X86_FEATURE_ZEN1))
		return -ENODEV;

But I'd suggest keeping this patch at the tail of the series, because 
if it regresses it would be easier to drop/revert.

Thanks,

	Ingo