RE: [PATCH v2 4/8] x86/spec_ctrl: Add sysctl knobs to enable/disable SPEC_CTRL feature

[Van De Ven, Arjan]

> >>  .macro DISABLE_IBRS
> >> -	ALTERNATIVE "jmp .Lskip_\@", "", X86_FEATURE_SPEC_CTRL
> >> +	testl	$1, dynamic_ibrs
> > On every system call we end up hammering on this 'dynamic_ibrs'
> > variable. And it looks like it can be flipped via the IPI mechanism.
> >
> > Would it make sense for this to be per-cpu?
> 
> It's probably better to either just make it __read_mostly or get the
> static branches that folks were suggesting actually working.

I still wonder if this isn't just better as a boot command line