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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB8F2C433F5 for ; Tue, 19 Oct 2021 17:05:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A72446113B for ; Tue, 19 Oct 2021 17:05:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234307AbhJSRII (ORCPT ); Tue, 19 Oct 2021 13:08:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45184 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231956AbhJSRIE (ORCPT ); Tue, 19 Oct 2021 13:08:04 -0400 Received: from mail-pj1-x1032.google.com (mail-pj1-x1032.google.com [IPv6:2607:f8b0:4864:20::1032]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DD5FDC06161C for ; Tue, 19 Oct 2021 10:05:51 -0700 (PDT) Received: by mail-pj1-x1032.google.com with SMTP id pi19-20020a17090b1e5300b0019fdd3557d3so362941pjb.5 for ; Tue, 19 Oct 2021 10:05:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=Dhgc7X/gBnEpv5sdM1TviQYfdTxsBoQA8Ow6mCcV/mk=; b=AEwxncFNWsQo91KKTgE1pw98+O6Y6y0qJdCgP59Xv15sTtUgafGnJnsegSJN/6FfpI QOlGIWWdb1IWScBvSanumTvoxTi2WXKMIR2HBj9b8Uz/8fJxwOoYKYcG6xu67jx5EXTn wA4xiUKcI3VNr6kNF1bJuBF3ch9OFo1JE7tCj4Zr5o7da6YfWVkH1pck+5ZnGqIeh+iw 66qBnuLu67B/BmFMe+V1dL1yU1XvpYuhpzA3OI9jIQ3OvRYTYuA4Il6GZpOgU5FzZ3Xx DRAUO90K9rMw/Lqhe0Mm1SipTO6ClNK5nBIIjeS1hN1U2Ts73MSIavQSiT9YODg6acvy RUrA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=Dhgc7X/gBnEpv5sdM1TviQYfdTxsBoQA8Ow6mCcV/mk=; b=rKjxfVN+jtLIBrtgHz8INEewQVJ22sFTLbihr3+6pG3xiVt9sBEInaqKhezmyC7FN5 1KRompK7cosIhPczyoa0kzLL0oH0QWluk5yOIDC6/eAWMzGcg/jY5fDt2THK0z7dju6W d4epteSk1k2ChyxPpwp20As1STSAHyjeNmD1z0mFbiBP4m/H/bzWs7/EdDxlkIyDLtGy lyQKQxEFyDoKIs1sZuF4pT2g7UGFYCBcFTcizt0ZPOREh8cD3rgT0+iYDs/FSzGrGMZ7 dgYWSkg8ZE0AActvS2pz8rXRSvO6iPkO+0/6hII0F0mHa3vQm8OE5U+G5+VM6PZV6c11 uH8Q== X-Gm-Message-State: AOAM533c+YEUdbYKu/CRgcIelgVjyXC4ReWD/nlEvGsbJvaQ0g1yD5QG OzsYA36ipB9oZZTd6Bhh4aXweQ== X-Google-Smtp-Source: ABdhPJxTxyKiO6N70mAz7RKEshK28Fj7jJA9XTer0vPp319bIvSVawfu/sogQLU0ELLPaoXJgjz3SA== X-Received: by 2002:a17:90a:9f44:: with SMTP id q4mr1231910pjv.136.1634663150914; Tue, 19 Oct 2021 10:05:50 -0700 (PDT) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id u2sm16465047pfi.120.2021.10.19.10.05.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Oct 2021 10:05:50 -0700 (PDT) Date: Tue, 19 Oct 2021 17:05:46 +0000 From: Sean Christopherson To: Chenyi Qiang Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Tony Luck , Fenghua Yu , Xiaoyao Li , linux-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH] x86/bus_lock: Don't assume the init value of DEBUGCTLMSR.BUS_LOCK_DETECT to be zero Message-ID: References: <20210901084004.5393-1-chenyi.qiang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210901084004.5393-1-chenyi.qiang@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 01, 2021, 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. This feels like the kernel should explicitly zero out the entire MSR somewhere in the generic boot flow. E.g. something like this somewhere. #ifndef CONFIG_X86_DEBUGCTLMSR if (boot_cpu_data.x86 < 6) return; #endifa wrmsrl(MSR_IA32_DEBUGCTLMSR, 0);