linux-kernel - Re: [PATCH] x86: static_cpu_has_safe: discard dynamic check after init

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Message-ID: <20160118183921.GH12651@pd.tnic>
Date:	Mon, 18 Jan 2016 19:39:21 +0100
From:	Borislav Petkov <bp@...e.de>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Brian Gerst <brgerst@...il.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] x86: static_cpu_has_safe: discard dynamic check after
 init

On Mon, Jan 18, 2016 at 10:29:24AM -0800, Andy Lutomirski wrote:
> I think that, if we can make static_cpu_has be unconditionally safe as
> a result

Problem with this is the additional .altinstructions entry for
X86_FEATURE_ALWAYS. And sometimes you don't really need to use the _safe
variant when you know you're safe.

> and get rid of warn_pre_alternatives,

That's off by default, behind CONFIG_X86_DEBUG_STATIC_CPU_HAS.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--