Re: [PATCH 0/4] x86/cpu: Use SERIALIZE in sync_core()

From: Ingo Molnar
Date: Mon Jul 27 2020 - 07:07:23 EST

* Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx> wrote:

> A recent submission to LKML introduced a CPU feature flag for a new
> Intel architecture Serializing Instruction, SERIALIZE [1]. Unlike the
> existing Serializing Instructions, this new instruction does not have
> side effects such as clobbering registers or exiting to a hypervisor.
> As stated in the Intel "extensions" (ISE) manual [2], this instruction
> will appear first in Sapphire Rapids and Alder Lake.
> Andy Lutomirski suggested to use this instruction in sync_core() as it
> serves the very purpose of this function [3].
> For completeness, I picked patch #3 from Cathy's series (and has become
> patch #1 here) [1]. Her series depends on such patch to build correctly.
> Maybe it can be merged independently while the discussion continues?
> Thanks and BR,
> Ricardo
> [1].
> [2].
> [3].
> Ricardo Neri (4):
> x86/cpufeatures: Add enumeration for SERIALIZE instruction
> x86/cpu: Relocate sync_core() to sync_core.h
> x86/cpu: Refactor sync_core() for readability
> x86/cpu: Use SERIALIZE in sync_core() when available

I've picked up the first 3 preparatory patches into tip:x86/cpu, as
they are valid improvements even without the 4th patch. The actual
functionality in the 4th patch still needs work.