Re: [patch 05/24] x86/speculation: Disable STIBP when enhanced IBRS is in use

From: Thomas Gleixner
Date: Wed Nov 21 2018 - 17:01:11 EST


On Wed, 21 Nov 2018, Thomas Gleixner wrote:
> On Wed, 21 Nov 2018, Borislav Petkov wrote:
> > > static char *stibp_state(void)
> > > {
> > > + if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
> > > + return "";
> >
> > If
> > spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED
> >
> > then SPEC_CTRL_STIBP should not be set in x86_spec_ctrl_base
> > (stibp_needed() prevents the setting in arch_smt_update()) so the above
> > check should not be needed.
> >
> > I *think*.
>
> Yes, makes sense.

For this patch, but for the final thing it does not.

Thanks,

tglx