RE: [PATCH 0/7] IBRS patch series

[Van De Ven, Arjan]

> On Fri, Jan 05, 2018 at 04:37:30PM +0000, David Woodhouse wrote:
> > You are completely ignoring pre-Skylake here.
> >
> > On pre-Skylake, retpoline is perfectly sufficient and it's a *lot*
> > faster than the IBRS option which is almost prohibitively slow.
> >
> > We didn't do it just for fun. And it's working fine; it isn't *that*
> > complex.
> 
> How do you enable IBRS when the CPU switches to SMM?

you do not need to. SMM takes care of itself.