linux-kernel - [PATCH 0/4] x86/cpu: Use SERIALIZE in sync

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Message-Id: <20200727043132.15082-1-ricardo.neri-calderon@linux.intel.com>
Date:   Sun, 26 Jul 2020 21:31:28 -0700
From:   Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...e.de>,
        Andy Lutomirski <luto@...nel.org>, x86@...nel.org
Cc:     Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Cathy Zhang <cathy.zhang@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Kyung Min Park <kyung.min.park@...el.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        linux-kernel@...r.kernel.org,
        Ricardo Neri <ricardo.neri@...el.com>,
        Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Subject: [PATCH 0/4] x86/cpu: Use SERIALIZE in sync_core() 

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]. https://lore.kernel.org/kvm/1594088183-7187-1-git-send-email-cathy.zhang@intel.com/
[2]. https://software.intel.com/sites/default/files/managed/c5/15/architecture-instruction-set-extensions-programming-reference.pdf
[3]. https://lore.kernel.org/kvm/CALCETrWudiF8G8r57r5i4JefuP5biG1kHg==0O8YXb-bYS-0BA@mail.gmail.com/

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

 arch/x86/include/asm/cpufeatures.h   |  1 +
 arch/x86/include/asm/processor.h     | 64 ----------------------
 arch/x86/include/asm/special_insns.h |  4 ++
 arch/x86/include/asm/sync_core.h     | 80 ++++++++++++++++++++++++++++
 arch/x86/kernel/alternative.c        |  1 +
 arch/x86/kernel/cpu/mce/core.c       |  1 +
 drivers/misc/sgi-gru/grufault.c      |  1 +
 drivers/misc/sgi-gru/gruhandles.c    |  1 +
 drivers/misc/sgi-gru/grukservices.c  |  1 +
 9 files changed, 90 insertions(+), 64 deletions(-)

-- 
2.17.1