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 DA06CC43441 for ; Mon, 19 Nov 2018 20:47:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A8EE32080C for ; Mon, 19 Nov 2018 20:47:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A8EE32080C 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 S1730849AbeKTHM1 (ORCPT ); Tue, 20 Nov 2018 02:12:27 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:39719 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730795AbeKTHM1 (ORCPT ); Tue, 20 Nov 2018 02:12:27 -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 1gOqRR-0002Wd-Ca; Mon, 19 Nov 2018 21:46:45 +0100 Date: Mon, 19 Nov 2018 21:46:44 +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: Message-ID: References: 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 Fri, 16 Nov 2018, Tim Chen wrote: > +static const struct { > + const char *option; > + enum spectre_v2_app2app_mitigation_cmd cmd; > + bool secure; > +} app2app_options[] = { > + { "off", SPECTRE_V2_APP2APP_CMD_NONE, false }, > + { "lite", SPECTRE_V2_APP2APP_CMD_LITE, false }, > + { "strict", SPECTRE_V2_APP2APP_CMD_STRICT, false }, > + { "auto", SPECTRE_V2_APP2APP_CMD_AUTO, false }, > + /* > + * The "on" option is kept as last entry. It is implied by > + * spectre_v2=on boot parameter and it is not checked > + * in spectre_v2_app2app boot parameter. > + */ > + { "on", SPECTRE_V2_APP2APP_CMD_FORCE, true }, FORCE is the same as STRICT. What's the point? > @@ -376,6 +464,8 @@ static void __init spectre_v2_select_mitigation(void) > { > enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline(); > enum spectre_v2_mitigation mode = SPECTRE_V2_NONE; > + enum spectre_v2_app2app_mitigation_cmd app2app_cmd; > + enum spectre_v2_app2app_mitigation app2app_mode; > > /* > * If the CPU is not affected and the command line mode is NONE or AUTO > @@ -452,12 +542,6 @@ static void __init spectre_v2_select_mitigation(void) > setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW); > pr_info("Spectre v2 / SpectreRSB mitigation: Filling RSB on context switch\n"); > > - /* Initialize Indirect Branch Prediction Barrier if supported */ > - if (boot_cpu_has(X86_FEATURE_IBPB)) { > - setup_force_cpu_cap(X86_FEATURE_USE_IBPB); > - pr_info("Spectre v2 mitigation: Enabling Indirect Branch Prediction Barrier\n"); > - } > - > /* > * Retpoline means the kernel is safe because it has no indirect > * branches. Enhanced IBRS protects firmware too, so, enable restricted > @@ -474,6 +558,43 @@ static void __init spectre_v2_select_mitigation(void) > pr_info("Enabling Restricted Speculation for firmware calls\n"); > } > > + app2app_mode = SPECTRE_V2_APP2APP_NONE; > + if (!boot_cpu_has(X86_FEATURE_IBPB) || > + !boot_cpu_has(X86_FEATURE_STIBP)) > + goto set_app2app_mode; 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. Thanks, tglx