Re: [patch V2 00/28] x86/speculation: Remedy the STIBP/IBPB overhead

From: Thomas Gleixner
Date: Wed Nov 28 2018 - 09:24:43 EST

On Sun, 25 Nov 2018, Thomas Gleixner wrote:

> Thats hopefully the final version of this. Changes since V1:
> - Renamed the command line option and related code to spectre_v2_user= as
> suggested by Josh.
> - Thought more about the back to back optimization and finally left the
> IBPB code in switch_mm().
> It still removes the ptrace check for the always IBPB case. That's
> substantial overhead for dubious value now that the default is
> conditional (prctl/seccomp) IBPB.
> - Added two options which allow conditional STIBP and IBPB always mode.
> - Addressed the review comments
> Documentation is still work in progress. Thanks Andi for providing the
> first draft for it.
> Still based on tip.git x86/pti as it has been discussed to remove the
> minimal RETPOLINE bandaid from stable kernels as well.

I've integrated the latest review feedback and the change which plugs the
TIF async update issue and pushed all of it out to:

git:// x86/pti

For the stable 4.14.y and 4.19.y trees, I've collected the missing bits and
pieces and uploaded tarballs which contain everything ready for consumption:

sha256 of patches-spec-4.14.y.tar:

sha256 of patches-spec-4.19.y.tar:

Thanks everyone for review, discussion, testing ... !