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 7783FC64E7C for ; Wed, 2 Dec 2020 18:10:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1759B22201 for ; Wed, 2 Dec 2020 18:10:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389343AbgLBSKu (ORCPT ); Wed, 2 Dec 2020 13:10:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387580AbgLBSKt (ORCPT ); Wed, 2 Dec 2020 13:10:49 -0500 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A218C0617A7 for ; Wed, 2 Dec 2020 10:10:09 -0800 (PST) Received: from zn.tnic (p200300ec2f161b00329c23fffea6a903.dip0.t-ipconnect.de [IPv6:2003:ec:2f16:1b00:329c: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 E10E81EC04DB; Wed, 2 Dec 2020 19:10:07 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1606932608; 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=MtASgyvlr76Dpn4OvnF8VBFRlFtBFT2ievvOIOzSaZg=; b=emO6ydC7ipcgMAmsz42cdKbUyVth+vDSpm3f/UCra7Z272bHAwYlM87mVfV9PWNaSV3khs KtuubNtGKcpuAmk/CXtHeylps5+zuHHwockj021IPKBUGWPo13sLWTTWqbaEN0y/N4piku GEPO5wsXps7e266AcT55RHzJLOQ3Krc= Date: Wed, 2 Dec 2020 19:10:08 +0100 From: Borislav Petkov To: Tom Lendacky Cc: Arvind Sankar , 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: <20201202181008.GI2951@zn.tnic> References: <20201127171324.1846019-1-nivedita@alum.mit.edu> <20201127172747.GE13163@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 Wed, Dec 02, 2020 at 11:58:15AM -0600, Tom Lendacky wrote: > I believe this is geared towards performance. If the TSEG base address is > not 2MB aligned, then hardware has to break down a 2MB TLB entry if the OS > references the memory within the 2MB page that is before the TSEG base > address. This can occur whenever the 2MB TLB entry is re-installed because > of TLB flushes, etc. And if this gets reinstated properly, then that explanation belongs over it because nothing else explains what that thing did. So thanks for digging it out. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette