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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT 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 686A4C04EBB for ; Wed, 21 Nov 2018 00:33:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D45F5213A2 for ; Wed, 21 Nov 2018 00:33:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D45F5213A2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com 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 S1727095AbeKULFR (ORCPT ); Wed, 21 Nov 2018 06:05:17 -0500 Received: from mga14.intel.com ([192.55.52.115]:30241 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726877AbeKULFQ (ORCPT ); Wed, 21 Nov 2018 06:05:16 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 20 Nov 2018 16:33:20 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,259,1539673200"; d="scan'208";a="93650181" Received: from skl-02.jf.intel.com ([10.54.74.62]) by orsmga008.jf.intel.com with ESMTP; 20 Nov 2018 16:33:20 -0800 From: Tim Chen To: Jiri Kosina , Thomas Gleixner Cc: Tim Chen , Linus Torvalds , 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 , Greg KH , Dave Stewart , linux-kernel@vger.kernel.org, x86@kernel.org, stable@vger.kernel.org Subject: [Patch v6 03/16] x86/speculation: Disable STIBP when enhanced IBRS is in use Date: Tue, 20 Nov 2018 15:59:55 -0800 Message-Id: <98459d97781796d8fa04aecb7ed473b7c4e48956.1542757030.git.tim.c.chen@linux.intel.com> X-Mailer: git-send-email 2.9.4 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If enhanced IBRS is engaged, STIBP is redundant in mitigating Spectre v2 user space exploits from hyperthread sibling. Disable STIBP when enhanced IBRS is used. Signed-off-by: Tim Chen --- arch/x86/kernel/cpu/bugs.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 3a6f13b..199f27e 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -323,11 +323,16 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void) return cmd; } +/* Determine if STIBP should be always on. */ static bool stibp_needed(void) { if (spectre_v2_enabled == SPECTRE_V2_NONE) return false; + /* Using enhanced IBRS makes using STIBP unnecessary. */ + if (static_cpu_has(X86_FEATURE_USE_IBRS_ENHANCED)) + return false; + if (!boot_cpu_has(X86_FEATURE_STIBP)) return false; @@ -856,6 +861,9 @@ static ssize_t l1tf_show_state(char *buf) static char *stibp_state(void) { + if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED) + return ""; + if (x86_spec_ctrl_base & SPEC_CTRL_STIBP) return ", STIBP"; else -- 2.9.4