Re: [tip:x86/pti] x86/retpoline: Fill RSB on context switch for affected CPUs

[Andi Kleen]

On Sun, Jan 14, 2018 at 04:05:54PM -0800, Andi Kleen wrote:
> > +	if ((!boot_cpu_has(X86_FEATURE_PTI) &&
> > +	     !boot_cpu_has(X86_FEATURE_SMEP)) || is_skylake_era()) {
> > +		setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
> > +		pr_info("Filling RSB on context switch\n");
> > +	}
> 
> Missing an option to turn this off.

My earlier patch did this properly by folding it 
into the big option parser.

https://marc.info/?l=linux-kernel&m=151578282016915&w=2

-Andi