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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 BD623C432C3 for ; Thu, 21 Nov 2019 08:00:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 925B22089F for ; Thu, 21 Nov 2019 08:00:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="GoZ9xila" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726765AbfKUIAt (ORCPT ); Thu, 21 Nov 2019 03:00:49 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:40986 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726568AbfKUIAt (ORCPT ); Thu, 21 Nov 2019 03:00:49 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=8gPlSZbQ02kcEbKJM0Y3h0/eL8NsVxDSu6s427XCQMw=; b=GoZ9xilaHQ5yHwdrDb2FoVcEM 06eiKElTHZtJ4sQAIRxRe67aczP2JCGjDUl53DQNRHXO8ZdtyWoi7WES8Mmt/ZsIE0XR6LkH0y7Jp v4BX/TYY80fARlSMMl/09CHdZ/h24dSTZ9R8X/qhHKgLAdex5jCgWAitwCZV/mmUp0pMuqOEERpW5 5ctEs9M2NMuZnqDSFuR8zHp/zxL3OBhEGfNw/SnUR9Ni2igN4IRq9cW7fmJkv3txFZIsxJidJRq+G r72TsEm2+8HPOFIVWsAd7rV/5i4BehIvClicDQvqceii/k+CV/xAja3K+KcTocj98/+Rn4VQ/88Ac 1DRd2nSdA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iXhOL-0006JG-Lq; Thu, 21 Nov 2019 08:00:41 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 21D80300565; Thu, 21 Nov 2019 08:59:28 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E2A8A2B1648CB; Thu, 21 Nov 2019 09:00:38 +0100 (CET) Date: Thu, 21 Nov 2019 09:00:38 +0100 From: Peter Zijlstra To: Fenghua Yu Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , Tony Luck , Ashok Raj , Ravi V Shankar , linux-kernel , x86 Subject: Re: [PATCH v10 6/6] x86/split_lock: Enable split lock detection by kernel parameter Message-ID: <20191121080038.GK4097@hirez.programming.kicks-ass.net> References: <1574297603-198156-1-git-send-email-fenghua.yu@intel.com> <1574297603-198156-7-git-send-email-fenghua.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1574297603-198156-7-git-send-email-fenghua.yu@intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 20, 2019 at 04:53:23PM -0800, Fenghua Yu wrote: > Split lock detection is disabled by default. Enable the feature by > kernel parameter "split_lock_detect". > > Usually it is enabled in real time when expensive split lock issues > cannot be tolerated so should be fatal errors, or for debugging and > fixing the split lock issues to improve performance. > > Please note: enabling this feature will cause kernel panic or SIGBUS > to user application when a split lock issue is detected. ARGGGHH, by having this default disabled, firmware will _NEVER_ be exposed to this before it ships. How will you guarantee the firmware will not explode the moment you enable this?