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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 1103EC43441 for ; Mon, 19 Nov 2018 23:01:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BF3622089F for ; Mon, 19 Nov 2018 23:01:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BF3622089F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731968AbeKTJ1w (ORCPT ); Tue, 20 Nov 2018 04:27:52 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:39975 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731164AbeKTJ1w (ORCPT ); Tue, 20 Nov 2018 04:27:52 -0500 Received: from p4fea46ac.dip0.t-ipconnect.de ([79.234.70.172] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1gOsXu-0005Qt-PK; Tue, 20 Nov 2018 00:01:34 +0100 Date: Tue, 20 Nov 2018 00:01:34 +0100 (CET) From: Thomas Gleixner To: Tim Chen cc: Jiri Kosina , Tom Lendacky , Ingo Molnar , Peter Zijlstra , Josh Poimboeuf , Andrea Arcangeli , David Woodhouse , Andi Kleen , Dave Hansen , Casey Schaufler , Asit Mallick , Arjan van de Ven , Jon Masters , Waiman Long , linux-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [Patch v5 11/16] x86/speculation: Add Spectre v2 app to app protection modes In-Reply-To: <49d27ed3-dc44-042c-4941-31dedb2a56d2@linux.intel.com> Message-ID: References: <49d27ed3-dc44-042c-4941-31dedb2a56d2@linux.intel.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 19 Nov 2018, Tim Chen wrote: > On 11/19/2018 12:55 PM, Jiri Kosina wrote: > > On Mon, 19 Nov 2018, Thomas Gleixner wrote: > > > >> > >> So before that change IBPB was usable without STIBP, now not longer. What's > >> the rationale? > >> > >> This patch changes a gazillion things at once and is completely > >> unreviewable. > > > > The patchset actually ties together IBPB and STIBP pretty closely, which > > is IMO a good thing; there is no good reason why anone would want just one > > of those (or each in a different mode), at least before this magical > > coscheduling exists. > > > > But I guess this fact should be documented somewhere. > > > > Yes, it wouldn't make sense for having just one of those if a task > is worried about attack from user space. > > I'll document it. What? IBPB makes tons of sense even without STIBP. Thanks, tglx