Spectre V1 Mitigation, IBPB Support Sent In For Linux 4.16

Last week Meltdown/Spectre patch wrangler Thomas Gleixner sent in various code clean-ups for Retpolines and KPTI with Linux 4.16 while today more feature work has been submitted. This includes initial mitigation work for Spectre v1 as well as IBPB support...