linux-kernel - Re: [PATCH v2 01/29] x86: treewide: Introduce x86_vendor_amd_or

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Message-ID: <20250317214609.GJZ9iYId2LhWBgqQ10@fat_crate.local>
Date: Mon, 17 Mar 2025 22:46:09 +0100
From: Borislav Petkov <bp@...en8.de>
To: Ingo Molnar <mingo@...nel.org>
Cc: "Ahmed S. Darwish" <darwi@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	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 v2 01/29] x86: treewide: Introduce
 x86_vendor_amd_or_hygon()

On Mon, Mar 17, 2025 at 10:42:09PM +0100, Ingo Molnar wrote:
> 
> * Ahmed S. Darwish <darwi@...utronix.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)));

No, it's not.

Hygon is family 0x18 AFAIK and ZEN1 is not.

Just drop this patch.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette