linux-kernel - Re: [PATCH v2 2/2] cpu: Ignore "mitigations" kernel parameter if CPU

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Date: Wed, 24 Apr 2024 08:48:38 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Borislav Petkov <bp@...en8.de>
Cc: Josh Poimboeuf <jpoimboe@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, 
	Ingo Molnar <mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	Peter Zijlstra <peterz@...radead.org>, linux-kernel@...r.kernel.org, 
	Stephen Rothwell <sfr@...b.auug.org.au>, Michael Ellerman <mpe@...erman.id.au>, 
	Geert Uytterhoeven <geert@...ux-m68k.org>, Will Deacon <will@...nel.org>, 
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v2 2/2] cpu: Ignore "mitigations" kernel parameter if CPU_MITIGATIONS=n

On Wed, Apr 24, 2024, Borislav Petkov wrote:
> On Tue, Apr 23, 2024 at 10:39:40PM -0700, Josh Poimboeuf wrote:
> > On Fri, Apr 19, 2024 at 05:05:55PM -0700, Sean Christopherson wrote:
> > > +#ifdef CONFIG_CPU_MITIGATIONS
> > >  extern bool cpu_mitigations_off(void);
> > >  extern bool cpu_mitigations_auto_nosmt(void);
> > > +#else
> > > +static inline bool cpu_mitigations_off(void)
> > > +{
> > > +	return false;
> > > +}
> > 
> > This should probably return true?

/facepalm

Glad you were paying attention, as I was clearly not.  I double checked that
flipping that to true does indeed force off mitigations.

> Right, I'll fix it up while applying and send them linuswards this
> weekend so that 6.9 releases fixed.

Thanks!