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

[Van De Ven, Arjan]

> Hello,
> 
> On Wed, Jan 10, 2018 at 02:46:22PM +0100, Thomas Gleixner 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.
> 
> Other comments/code from Tim Chen, and Dave Hansen and most important
> the ibrs_enabled 2 description and implementation on lkml, makes me
> still wonder if even Arjan may have misunderstood some detail about
> IBRS semantics too.

I spent the better part of the last 6 months in dungeons with CPU designers trying to to figure out what we could and could not do. I'm pretty darn sure I know the details.