[PATCH v3 0/9] x86/microcode: Refactor NMI-based rendezvous mechanism to stop-machine

["Chang S. Bae" <chang.seok.bae@intel.com>]

Hi all,

First of all, apologies for such a long delay in posting the revision.
This series has almost fallen through the cracks unless Boris chimed in.
Even then, it took me a bit to revisit the series and post this.

Let me summarize the change since V2 [1]. Most of the changes are in the
stop-machine facility itself, addressing feedback from Sashiko, both from
the public [2] and from internal runs:

 * Simplify NMI handling to avoid false handling (patch2).
 * Use internal functions to avoid instrumentable functions (patch2).
 * Prevent use during boot (patch3).
 * Tighten to online CPUs only (patch3).

Each patch includes more detail (patch2-5). I've also noted some thoughts
on the Sashiko feedback where the concern looks less practical (patch5).

The patch set is available in this repository:
 git://github.com/intel-staging/microcode.git nmi-stop-machine_v3

Note this cover highlights a summary of changes only. Instead, V2 [1] has
lengthy cover letter that provides more background and design summary.

Thanks,
Chang

[1] V2: https://lore.kernel.org/20260331014251.86353-12-chang.seok.bae@intel.com
[2] https://sashiko.dev/#/patchset/20260331014251.86353-1-chang.seok.bae%40intel.com

Chang S. Bae (7):
  stop_machine: Refactor multi-CPU stop glue code
  stop_machine: Add NMI-based execution path
  stop_machine: Introduce stop_machine_nmi_cpuslocked()
  x86/microcode: Distinguish NMI control path on stop-machine callback
  x86/microcode: Use stop-machine NMI facility
  x86/nmi: Simplify offline microcode handler invocation
  x86/microcode: Remove microcode_nmi_handler_enable

David Kaplan (2):
  x86/apic: Implement self-NMI support
  x86/nmi: Support NMI stop-machine handler

 arch/Kconfig                         |   3 +
 arch/x86/Kconfig                     |   1 +
 arch/x86/include/asm/microcode.h     |  11 --
 arch/x86/kernel/apic/ipi.c           |  10 ++
 arch/x86/kernel/cpu/microcode/core.c |  35 ++----
 arch/x86/kernel/nmi.c                |   7 +-
 include/linux/stop_machine.h         |  43 +++++++
 kernel/stop_machine.c                | 180 ++++++++++++++++++++++++---
 8 files changed, 232 insertions(+), 58 deletions(-)


base-commit: 24a19b953e2a3d0ea5a8c4951a0ab8f32720c907
-- 
2.53.0