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 75182C43441 for ; Tue, 20 Nov 2018 00:02:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3F57D20870 for ; Tue, 20 Nov 2018 00:02:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3F57D20870 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 S1732228AbeKTK2t (ORCPT ); Tue, 20 Nov 2018 05:28:49 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:40071 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726431AbeKTK2t (ORCPT ); Tue, 20 Nov 2018 05:28:49 -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 1gOtUj-0006AP-CI; Tue, 20 Nov 2018 01:02:21 +0100 Date: Tue, 20 Nov 2018 01:02:20 +0100 (CET) From: Thomas Gleixner To: Jiri Kosina cc: Dave Hansen , Tim Chen , Tom Lendacky , Ingo Molnar , Peter Zijlstra , Josh Poimboeuf , Andrea Arcangeli , David Woodhouse , Andi Kleen , 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: Message-ID: References: <49d27ed3-dc44-042c-4941-31dedb2a56d2@linux.intel.com> <591a5109-ffef-b17f-38e3-12082d229451@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 Tue, 20 Nov 2018, Jiri Kosina wrote: > On Mon, 19 Nov 2018, Dave Hansen wrote: > > > > What? IBPB makes tons of sense even without STIBP. > > > > I'm lost. :) > > > > I don't think anyone is talking about using STIBP *everywhere* that IBPB > > is in-use. > > > > We're just guessing that, if anybody is paranoid enough to ask for IBPB, > > *and* they have SMT, they almost certainly want STIBP too. > > I think you are not lost :) and this is exactly what makes sense, and what > Tim's patchset implements. Tries to implement perhaps. Unless IBPB is never available when STIBP is not available, but according to documentation that's unlikely because STIBP can be unset when the CPU does not support HT at all. Thanks, tglx