From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 686E7C4338F for ; Wed, 18 Aug 2021 15:40:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4430C610A1 for ; Wed, 18 Aug 2021 15:40:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239823AbhHRPkp (ORCPT ); Wed, 18 Aug 2021 11:40:45 -0400 Received: from mga04.intel.com ([192.55.52.120]:39016 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237598AbhHRPko (ORCPT ); Wed, 18 Aug 2021 11:40:44 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10080"; a="214507584" X-IronPort-AV: E=Sophos;i="5.84,330,1620716400"; d="scan'208";a="214507584" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Aug 2021 08:36:13 -0700 X-IronPort-AV: E=Sophos;i="5.84,330,1620716400"; d="scan'208";a="521113180" Received: from otcwcpicx3.sc.intel.com ([172.25.55.73]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Aug 2021 08:36:12 -0700 Date: Wed, 18 Aug 2021 15:36:06 +0000 From: Fenghua Yu To: Xiaoyao Li Cc: linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org, Thomas Gleixner , Tony Luck , x86@kernel.org Subject: Re: [tip: x86/splitlock] Documentation/x86: Add buslock.rst Message-ID: References: <20210419214958.4035512-2-fenghua.yu@intel.com> <162134906278.29796.13820849234959966822.tip-bot2@tip-bot2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 18, 2021 at 09:59:49AM +0800, Xiaoyao Li wrote: > On 5/18/2021 10:44 PM, tip-bot2 for Fenghua Yu wrote: > I'm wonder if using only one "split_lock_detect" parameter for those two > features is good/correct. > > In fact, split lock is just one type of bus lock. There are two types bus > lock: > 1) split lock, lock on WB memory across multiple cache lines; > 2) lock on non-WB memory; > > As current design, if both features are available, it only enables #AC for > split lock either for "warn" or "fatal". Thus we cannot capture any bus lock > due to 2) lock on non-WB memory. > > Why not provide separate parameter for them? e.g., split_lock_detect and > bus_lock_detect. Then they can be configured and enabled independently. #AC for split lock is a model specific feature and only available on limited (and legacy) platforms. #DB for bus lock is an architectural feature and will replace #AC for split lock in future platforms. The platforms that support both of them are very rare (maybe only one AFAIK). Adding two parameters makes code and usage complex while only one platform may get benefit in reality. Thanks. -Fenghua