RE: [patch RFC 5/5] x86/speculation: Add basic speculation control code

[Thomas Gleixner]

On Wed, 10 Jan 2018, Van De Ven, Arjan wrote:
> > So here is the simple list of questions all to be answered with YES or
> > NO. I don't want to see any of the 'but, though ...'. We all know by now
> > that it's CPU dependent and slow and whatever and that IBRS_ATT will be in
> > future CPUs. So get your act together and tell a clear YES or NO.

> > 2) Does toggle mode of IBRS require retpoline ?
> 
> NO
> 
> > 
> > 3) Does toggle mode of IBRS require RSB stuffing ?
> 
> Only for the VM exit case

Ok.

> > 
> > 4) Exist CPUs which require IBRS to be selected automatically ?
> 
> I do not understand your question exactly

Whether the kernel should enable IBRS by default on certain models. And if
yes, which ones.

Thanks,

	tglx