linux-kernel - Re: [tip: x86/cpu] x86/cpufeatures: Add {REQUIRED,DISABLED} feature configs

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Message-ID: <Z882Cj2sO5wDWZIs@gmail.com>
Date: Mon, 10 Mar 2025 19:57:14 +0100
From: Ingo Molnar <mingo@...nel.org>
To: "H. Peter Anvin" <hpa@...or.com>
Cc: linux-kernel@...r.kernel.org,
	"tip-bot2 for H. Peter Anvin (Intel)" <tip-bot2@...utronix.de>,
	linux-tip-commits@...r.kernel.org, "Xin Li (Intel)" <xin@...or.com>,
	"Borislav Petkov (AMD)" <bp@...en8.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>, x86@...nel.org
Subject: Re: [tip: x86/cpu] x86/cpufeatures: Add {REQUIRED,DISABLED} feature
 configs


* H. Peter Anvin <hpa@...or.com> wrote:

> >+config X86_DISABLED_FEATURE_FRED
> >+	def_bool y
> >+	depends on !X86_FRED
> >+
> >+config X86_DISABLED_FEATURE_SEV_SNP
> >+	def_bool y
> >+	depends on !KVM_AMD_SEV
> >+
> >+config X86_DISABLED_FEATURE_INVLPGB
> >+	def_bool y
> >+	depends on !BROADCAST_TLB_FLUSH
> 
> I think it is worth noting that the list here was intentionally 
> unchanged from the previous definitions, but that several of these 
> could and probably should be overhauled.

Yeah, note that this list was *not* unchanged since the -v1 submission, 
there's two new dependencies we added since -v1 which ended with the 
FRED entry:

 - X86_DISABLED_FEATURE_INVLPGB dependency we added today, which is due 
   to a new feature freshly merged into tip:x86/mm.

 - X86_DISABLED_FEATURE_SEV_SNP was added a bit back - that too is a 
   fresh sub-feature.

So we are aware, but we are also limited by what we notice. :-)

> For example, CPUID is actually required by any i586+ configuration.

Mind sending patches for anything you can think of? This series is now 
headed for v6.15 via tip:x86/cpu, modulo any unexpected catastrophes in 
-next testing.

Thanks,

	Ingo