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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 43FADC433E0 for ; Sat, 13 Mar 2021 05:50:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1765464EFD for ; Sat, 13 Mar 2021 05:50:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230441AbhCMFti (ORCPT ); Sat, 13 Mar 2021 00:49:38 -0500 Received: from mga02.intel.com ([134.134.136.20]:62600 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233235AbhCMFt0 (ORCPT ); Sat, 13 Mar 2021 00:49:26 -0500 IronPort-SDR: bbGYqczS5QwKaEljbq9ML33naW7zyKyJIht81+Yyf+JmL0pxTZ2Tr35KKKM/ZH+p8Yo9hEZ9WK 2trI4cItzEBQ== X-IronPort-AV: E=McAfee;i="6000,8403,9921"; a="176050569" X-IronPort-AV: E=Sophos;i="5.81,245,1610438400"; d="scan'208";a="176050569" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Mar 2021 21:49:25 -0800 IronPort-SDR: UP8nQI/+bC3dMdKw7Yyi9/CZfylm+uwR4NWT5zCaMBjwl4+Gg7PvHtliGgIC4Kw9dtbUjl9kfT cXGpHXtwxFtw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,245,1610438400"; d="scan'208";a="372880406" Received: from otcwcpicx3.sc.intel.com ([172.25.55.73]) by orsmga006.jf.intel.com with ESMTP; 12 Mar 2021 21:49:25 -0800 From: Fenghua Yu To: "Thomas Gleixner" , "Ingo Molnar" , "Borislav Petkov" , "Peter Zijlstra" , "Tony Luck" , "Randy Dunlap" , "Xiaoyao Li " , "Ravi V Shankar" Cc: "linux-kernel" , "x86" , Fenghua Yu Subject: [PATCH v5 3/3] Documentation/admin-guide: Change doc for split_lock_detect parameter Date: Sat, 13 Mar 2021 05:49:10 +0000 Message-Id: <20210313054910.2503968-4-fenghua.yu@intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210313054910.2503968-1-fenghua.yu@intel.com> References: <20210313054910.2503968-1-fenghua.yu@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since #DB for bus lock detect changes the split_lock_detect parameter, update the documentation for the changes. Signed-off-by: Fenghua Yu Reviewed-by: Tony Luck Acked-by: Randy Dunlap --- Change Log: v5: - Remove N < HZ/2 check info in the doc (Thomas). v4: - Fix a ratelimit wording issue in the doc (Randy). - Patch 4 is acked by Randy (Randy). v3: - Enable Bus Lock Detection when fatal to handle bus lock from non-WB (PeterZ). v1: - Fix a few wording issues (Randy). RFC v2: - Simplify the documentation (Randy). .../admin-guide/kernel-parameters.txt | 30 +++++++++++++++---- 1 file changed, 24 insertions(+), 6 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 04545725f187..16b2e1c45d04 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5100,27 +5100,45 @@ spia_peddr= split_lock_detect= - [X86] Enable split lock detection + [X86] Enable split lock detection or bus lock detection When enabled (and if hardware support is present), atomic instructions that access data across cache line - boundaries will result in an alignment check exception. + boundaries will result in an alignment check exception + for split lock detection or a debug exception for + bus lock detection. off - not enabled - warn - the kernel will emit rate limited warnings + warn - the kernel will emit rate-limited warnings about applications triggering the #AC - exception. This mode is the default on CPUs - that supports split lock detection. + exception or the #DB exception. This mode is + the default on CPUs that support split lock + detection or bus lock detection. Default + behavior is by #DB if both features are + enabled in hardware. fatal - the kernel will send SIGBUS to applications - that trigger the #AC exception. + that trigger the #AC exception or the #DB + exception. If both features are enabled in + hardware, split lock triggers #AC and bus + lock from non-WB triggers #DB. + + ratelimit:N - + Set rate limit to N bus locks per second + for bus lock detection. 0 < N. + Only applied to non-root users. + + N/A for split lock detection. If an #AC exception is hit in the kernel or in firmware (i.e. not while executing in user mode) the kernel will oops in either "warn" or "fatal" mode. + #DB exception for bus lock is triggered only when + CPL > 0. + srbds= [X86,INTEL] Control the Special Register Buffer Data Sampling (SRBDS) mitigation. -- 2.30.2