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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 32A43C4361A for ; Thu, 3 Dec 2020 16:45:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D397D207A5 for ; Thu, 3 Dec 2020 16:45:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731364AbgLCQo6 (ORCPT ); Thu, 3 Dec 2020 11:44:58 -0500 Received: from mail.skyhub.de ([5.9.137.197]:55030 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726958AbgLCQo5 (ORCPT ); Thu, 3 Dec 2020 11:44:57 -0500 Received: from zn.tnic (p200300ec2f0dc5004496c992b512bfd2.dip0.t-ipconnect.de [IPv6:2003:ec:2f0d:c500:4496:c992:b512:bfd2]) (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 7F1261EC0434; Thu, 3 Dec 2020 17:44:16 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1607013856; 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=/DmkWKu0h3mwMioedlGpNuFallczqE7TKT9kOW5E40c=; b=JZtCYM726FRpT80jAPoqR+Rcwj93drucEOd0Nx8xaqQ034meCQ8vcPWUcLQMGLdKH5BFRe u2gAu3xdfS3WL/7Q4xu5kkZWo4dh/DuExxa0enp6U1ALIJRXhmvUJVSG6v3zv0mQZ3k6hs W9Uu02t9En7V9Ip68K1aJhweDgPLRQ8= Date: Thu, 3 Dec 2020 17:44:11 +0100 From: Borislav Petkov To: Arvind Sankar Cc: Tom Lendacky , x86@kernel.org, Kim Phillips , Yazen Ghannam , Pu Wen , linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86/cpu/amd: Remove dead code for TSEG region remapping Message-ID: <20201203164411.GK3059@zn.tnic> References: <20201127171324.1846019-1-nivedita@alum.mit.edu> <20201127172747.GE13163@zn.tnic> <20201203084857.GD3059@zn.tnic> 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 Thu, Dec 03, 2020 at 11:14:06AM -0500, Arvind Sankar wrote: > Do any of them have it mapped at all, regardless of the alignment? There > seems to be nothing else in the kernel that ever looks at the TSEG MSR, > so I would guess that it has to be non-RAM in the E820 map, otherwise > nothing would prevent the kernel from allocating and using that space. Ha, that's a very good question. If all those BIOSes from K8 onwards would put the TSEG in a non-RAM area and after 66520ebc2df3 ("x86, mm: Only direct map addresses that are marked as E820_RAM") (great investigative work, btw, thanks for that!) then we can simply say that that splitting is not needed anymore. Maybe Tom can ask BIOS people whether they always did that - that being to put the TSEG into a non-RAM area. I can boot my debug patch on my boxes here but that doesn't mean a whole lot... Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette