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 6BD56C32772 for ; Mon, 22 Aug 2022 08:28:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233365AbiHVI2c (ORCPT ); Mon, 22 Aug 2022 04:28:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33836 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233411AbiHVI2Z (ORCPT ); Mon, 22 Aug 2022 04:28:25 -0400 Received: from mail.skyhub.de (mail.skyhub.de [5.9.137.197]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 816E6B7C9; Mon, 22 Aug 2022 01:28:18 -0700 (PDT) Received: from zn.tnic (p200300ea971b9882329c23fffea6a903.dip0.t-ipconnect.de [IPv6:2003:ea:971b:9882:329c: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 E8CAA1EC04DA; Mon, 22 Aug 2022 10:28:12 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1661156893; 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=3t9+6nfiuQKFvxF6QSwH6wfi0OEdPc0eB0BQ88sluiw=; b=LBTgUcDzl5EdkYRDDlSD9fBZ0rURljXWITRA9M9N8bU0uOJgF0ELIcgHu1BNxGDLbs8SjS rzXJHZvhI0nkzVUuapeB4U5odChwEb15KS+ReeR2th/1wYx7PdbXEUpL1kh3/p9CNFT3dm aQbFCNV0IyjQbUqZostPTwFiS+hKwUg= Date: Mon, 22 Aug 2022 10:28:08 +0200 From: Borislav Petkov To: Juergen Gross Cc: xen-devel@lists.xenproject.org, x86@kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Dave Hansen , "H. Peter Anvin" , stable@vger.kernel.org Subject: Re: [PATCH v2 01/10] x86/mtrr: fix MTRR fixup on APs Message-ID: References: <20220820092533.29420-1-jgross@suse.com> <20220820092533.29420-2-jgross@suse.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 Mon, Aug 22, 2022 at 07:17:40AM +0200, Juergen Gross wrote: > And then there is mtrr_state_warn() in arch/x86/kernel/cpu/mtrr/generic.c > which has a comment saying: > > /* Some BIOS's are messed up and don't set all MTRRs the same! */ That thing also says: pr_info("mtrr: probably your BIOS does not setup all CPUs.\n"); pr_info("mtrr: corrected configuration.\n"); because it'll go and force on all CPUs the MTRR state it read from the BSP in mtrr_bp_init->get_mtrr_state. > Yes, the chances are slim to hit such a box, Well, my workstation says: $ dmesg | grep -i mtrr [ 0.391514] mtrr: your CPUs had inconsistent variable MTRR settings [ 0.395199] mtrr: probably your BIOS does not setup all CPUs. [ 0.399199] mtrr: corrected configuration. but that's the variable MTRRs. > but your reasoning suggests I should remove the related code? My reasoning says you should not do anything at all here - works as advertized. :-) -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette