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

[Thomas Gleixner]

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.

It's avaiable from git:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git WIP.x86/pti


Thanks,

	tglx

8<------------------------

 Documentation/admin-guide/kernel-parameters.txt |   56 ++
 Documentation/userspace-api/spec_ctrl.rst       |    9 
 arch/x86/Kconfig                                |    8 
 arch/x86/include/asm/msr-index.h                |    5 
 arch/x86/include/asm/nospec-branch.h            |   14 
 arch/x86/include/asm/spec-ctrl.h                |   18 
 arch/x86/include/asm/switch_to.h                |    3 
 arch/x86/include/asm/thread_info.h              |   18 
 arch/x86/include/asm/tlbflush.h                 |    8 
 arch/x86/kernel/cpu/bugs.c                      |  520 ++++++++++++++++++------
 arch/x86/kernel/process.c                       |   79 ++-
 arch/x86/kernel/process.h                       |   39 +
 arch/x86/kernel/process_32.c                    |   10 
 arch/x86/kernel/process_64.c                    |   10 
 arch/x86/mm/tlb.c                               |  109 +++--
 include/linux/ptrace.h                          |   17 
 include/linux/sched.h                           |    9 
 include/linux/sched/smt.h                       |   20 
 include/uapi/linux/prctl.h                      |    1 
 kernel/cpu.c                                    |   15 
 kernel/ptrace.c                                 |   10 
 kernel/sched/core.c                             |   19 
 kernel/sched/sched.h                            |    4 
 tools/include/uapi/linux/prctl.h                |    1 
 24 files changed, 745 insertions(+), 257 deletions(-)