Re: [PATCH 7/7] x86/bugs: Replace CONFIG_SPECTRE_BHI_{ON,OFF} with CONFIG_MITIGATION_SPECTRE_BHI

[Josh Poimboeuf]

On Thu, Apr 11, 2024 at 09:48:42AM +0200, Ingo Molnar wrote:
> > +++ b/arch/x86/kernel/cpu/bugs.c
> > @@ -1628,7 +1628,7 @@ enum bhi_mitigations {
> >  };
> >  
> >  static enum bhi_mitigations bhi_mitigation __ro_after_init =
> > -	IS_ENABLED(CONFIG_SPECTRE_BHI_ON) ? BHI_MITIGATION_ON : BHI_MITIGATION_OFF;
> > +	IS_ENABLED(CONFIG_MITIGATION_SPECTRE_BHI_ON) ? BHI_MITIGATION_ON : BHI_MITIGATION_OFF;
> 
> Uhm, after this patch there's no CONFIG_MITIGATION_SPECTRE_BHI_ON anymore, 
> which is kindof nasty, as IS_ENABLED() doesn't generate a build failure for 
> non-existent Kconfig variables IIRC ...
> 
> So AFAICT this patch turns on BHI unconditionally.
> 
> I've fixed as per the patch below, but please double check the end result 
> in tip:x86/urgent once I've pushed it out..

Oof, thanks.  The result in tip looks good.

We should add a permanent build time check to catch cases like this.

-- 
Josh