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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A6BB2C00140 for ; Tue, 2 Aug 2022 11:42:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236555AbiHBLmx (ORCPT ); Tue, 2 Aug 2022 07:42:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40594 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233384AbiHBLmv (ORCPT ); Tue, 2 Aug 2022 07:42:51 -0400 Received: from mail-ej1-x635.google.com (mail-ej1-x635.google.com [IPv6:2a00:1450:4864:20::635]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1565B2C11C for ; Tue, 2 Aug 2022 04:42:50 -0700 (PDT) Received: by mail-ej1-x635.google.com with SMTP id kb8so10868834ejc.4 for ; Tue, 02 Aug 2022 04:42:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=xf4P1T8AnkIqXYwvL450HeEFIE7Eqes26pNoIb9Mcxs=; b=p3kum8xc+iRcbA90Tzi41xwEVeNCXy+DtFajdGXmAnrfKAmMPXM6/2upvECeVUZlcj 5GNpOhofdo90I2VOuktoQ7+YqDt3J6bJrZqPzc9d+XYLrrUTU/9hKaxMCit9AI0c2gou QaUU/nVyQZnNFr1xficiwiIlF9AUtysMJOGLCjA3uQNMcqVTksj3hABeCEG+DJnvNAi6 iliNIQRh28fRHqkHVx7muequICN8lnZBdE51UHbnDPFMs46qANRlm1DaoH5bHGnY3BIT xMsfO0zT5kIGHFYKKxpx9FGw5b199rgoKbdZxlPbQ9qUI4Qp/HGYES0w+AEpbVcPVunR DvMQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=xf4P1T8AnkIqXYwvL450HeEFIE7Eqes26pNoIb9Mcxs=; b=Tv8osN3YBOMc/vGY1hNBAEpjtcrnVEuwVtH/Vw5UHWau9USlXzXV/oca9a4CSFRN7w VgdnxFDnnmC0uhIvN3rtMDi/R5xy1xNYXg5wpzoRIhSi4tJAW73SrZ+bIDQSpPZWnvXO 47LEE49bPlM6Q2G71RiIDm3kkGsDdfsg+HfusoFBEugYwVkvQoNLFFSa2x3L56cwUNgZ AeM3HAEBgIS/2tRlw7ux0Gx5DJ4PTJgdPkXS6hjLfL5FTf1qIx/p0+70gNsu3c7ip8BN llrX3uCB/ZSnLJnd4cLl80B1Z06XYIkuOjDGQgiILmn79ogYjUCZ8E8VEgep0ILKYUZB O43w== X-Gm-Message-State: AJIora+tvx4qk4ANZvDa7UOQpf8kghx2r+Rn52Mfd1imSpM7x5bKPB4b T4/Si5MyNSkoQQK3rWek3auug4vyZXk= X-Google-Smtp-Source: AGRyM1sExTKkqOhbTJvaUmP8MqzPQi9Ytf894HZYJIm3RYVpY2hlo4/bJT2txtQFy72VPNcqsnh+1w== X-Received: by 2002:a17:906:5d04:b0:722:f46c:b891 with SMTP id g4-20020a1709065d0400b00722f46cb891mr15778142ejt.4.1659440568594; Tue, 02 Aug 2022 04:42:48 -0700 (PDT) Received: from gmail.com (84-236-113-167.pool.digikabel.hu. [84.236.113.167]) by smtp.gmail.com with ESMTPSA id r9-20020a17090609c900b0072f5fa11d19sm6174840eje.202.2022.08.02.04.42.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Aug 2022 04:42:48 -0700 (PDT) Sender: Ingo Molnar Date: Tue, 2 Aug 2022 13:42:45 +0200 From: Ingo Molnar To: Chenyi Qiang Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Tony Luck , Fenghua Yu , linux-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [RESEND] x86/bus_lock: Don't assume the init value of DEBUGCTLMSR.BUS_LOCK_DETECT to be zero Message-ID: References: <20220802033206.21333-1-chenyi.qiang@intel.com> <897aa91c-9d45-e16a-9b09-849fab588cd7@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <897aa91c-9d45-e16a-9b09-849fab588cd7@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Chenyi Qiang wrote: > > > On 8/2/2022 6:51 PM, Ingo Molnar wrote: > > > > * Chenyi Qiang wrote: > > > > > It's possible that BIOS/firmware has set DEBUGCTLMSR_BUS_LOCK_DETECT, or > > > this kernel has been kexec'd from a kernel that enabled bus lock > > > detection. > > > > > > Disable bus lock detection explicitly if not wanted. > > > > Makes sense. > > > > Just curious: in what circumstances does the BIOS/firmware set > > DEBUGCTLMSR_BUS_LOCK_DETECT? Does it use it, or does it enable it for some > > spurious reason, without really using the feature? (Assuming you are aware > > of instances where this happened - or was this simply a hypothetical?) > > Yes, It's just a hypothetical for BIOS/firmware. Kexec is the real case I > met with this problem. Fair enough, I've tweaked the changelog a bit to de-emphasize the firmware angle, and applied your fix to tip:x86/urgent. Thanks, Ingo