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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 E633AC433FE for ; Wed, 22 Sep 2021 15:58:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CABC461168 for ; Wed, 22 Sep 2021 15:58:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236543AbhIVP7g (ORCPT ); Wed, 22 Sep 2021 11:59:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50176 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236523AbhIVP7e (ORCPT ); Wed, 22 Sep 2021 11:59:34 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D73EC061574 for ; Wed, 22 Sep 2021 08:58:04 -0700 (PDT) Received: from zn.tnic (p200300ec2f0efa00329c23fffea6a903.dip0.t-ipconnect.de [IPv6:2003:ec:2f0e:fa00:329c:23ff:fea6:a903]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id BB9641EC051E; Wed, 22 Sep 2021 17:57:58 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1632326278; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=ry9Z69LQArNbVtPmCuRDweOphdtc94L4dVIHpBekN7c=; b=NCb5G93fgk04Z2kWoYDwBQTP8e5F9qd58TBdUrkNmhNrC8qdF/up7c028VJBvnwal9xUYX Dv0ZbbDkFXiAgYsniyNqarrANQJUFV27++v1GQELTaOcVS5SiGraygAkQnkgP03prqJgCf VbqJxEOAIpJPHVvZCmLnEFCJ2nW3U1I= Date: Wed, 22 Sep 2021 17:57:52 +0200 From: Borislav Petkov To: "Luck, Tony" Cc: Yazen Ghannam , X86 ML , LKML Subject: Re: [PATCH 3/4] x86/mce: Get rid of msr_ops Message-ID: References: <2B1FFC77-A740-41AE-BF8C-FB238B9DF7F5@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 22, 2021 at 03:22:01PM +0000, Luck, Tony wrote: > Also: > > switch (enum) { > actions for every value of that enum > } > > doesn't need a default: option Right, my thought was to catch silly stuff like this here: diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c index b355ce737543..dfecf65e5407 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -1714,6 +1714,7 @@ static void __mcheck_cpu_init_clear_banks(void) continue; wrmsrl(mca_msr_reg(i, MCA_CTL), b->ctl); wrmsrl(mca_msr_reg(i, MCA_STATUS), 0); + wrmsrl(mca_msr_reg(i, 12), 0); } } but we already warn nicely there: [ 0.146457] unchecked MSR access error: WRMSR to 0x0 (tried to write 0x0000000000000000) at rIP: 0xffffffff8103234b (__mcheck_cpu_init_clear_banks+0x6b/0xe0) [ 0.147550] Call Trace: [ 0.147836] mcheck_cpu_init+0x16c/0x4a0 [ 0.148234] identify_cpu+0x3fe/0x670 [ 0.148607] identify_boot_cpu+0xc/0x94 [ 0.148995] check_bugs+0x26/0xaef [ 0.149353] ? __get_locked_pte+0x14a/0x200 [ 0.149777] start_kernel+0x602/0x621 [ 0.150153] secondary_startup_64_no_verify+0xb0/0xbb and the mce_rd/wrmsrl() wrappers even panic. So default case gone. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette