Re: [PATCH 6/6] x86/bugs: Clean-up verw mitigations

[Nikolay Borisov]

On 2.10.24 г. 17:46 ч., Daniel Sneddon wrote:
> On 10/2/24 07:20, Nikolay Borisov wrote:
> > > +	if (boot_cpu_has_bug(X86_BUG_MDS)) {
> > >    		mds_mitigation = MDS_MITIGATION_FULL;
> > >    		mds_select_mitigation();
> > > +	}  else {
> > > +		mds_mitigation = MDS_MITIGATION_OFF;
> > >    	}
> >
> > BUt with this logic if CONFIG_MITIGATION_MDS is deselected meaning
> > mds_mitigations will have the value MDS_MITIGATION_OFF, yet now you will
> > set it to _FULL thereby overriding the compile-time value of the user.
> > So shouldn't this condition be augmented to alsoo consider
> > CONFIG_MITIGATION_MDS compile time value?
>
> CONFIG_MITIGATION_MDS is used to set the value of the mds_mitigation variable.
> Same goes for all the other mitigations touched here. Those variables are
> checked in verw_mitigations_disabled() which is called just before this code. If
> all of them are configured off, we return without enabling any of the mitigations.

Ah, indeed.

Reviewed-by: Nikolay Borisov <nik.borisov@xxxxxxxx>