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=-12.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 EBE6AC43441 for ; Wed, 28 Nov 2018 14:23:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B797420832 for ; Wed, 28 Nov 2018 14:23:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B797420832 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.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 S1728597AbeK2BZI (ORCPT ); Wed, 28 Nov 2018 20:25:08 -0500 Received: from terminus.zytor.com ([198.137.202.136]:41307 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727832AbeK2BZI (ORCPT ); Wed, 28 Nov 2018 20:25:08 -0500 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id wASEMbHL2320935 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Wed, 28 Nov 2018 06:22:37 -0800 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id wASEMa1K2320929; Wed, 28 Nov 2018 06:22:36 -0800 Date: Wed, 28 Nov 2018 06:22:36 -0800 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Tim Chen Message-ID: Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, thomas.lendacky@amd.com, aarcange@redhat.com, hpa@zytor.com, asit.k.mallick@intel.com, tglx@linutronix.de, casey.schaufler@intel.com, dwmw@amazon.co.uk, longman9394@gmail.com, jcm@redhat.com, arjan@linux.intel.com, jkosina@suse.cz, gregkh@linuxfoundation.org, tim.c.chen@linux.intel.com, dave.hansen@intel.com, jpoimboe@redhat.com, luto@kernel.org, peterz@infradead.org, ak@linux.intel.com, david.c.stewart@intel.com, torvalds@linux-foundation.org, keescook@chromium.org Reply-To: tim.c.chen@linux.intel.com, jpoimboe@redhat.com, dave.hansen@intel.com, luto@kernel.org, peterz@infradead.org, ak@linux.intel.com, david.c.stewart@intel.com, torvalds@linux-foundation.org, keescook@chromium.org, mingo@kernel.org, linux-kernel@vger.kernel.org, aarcange@redhat.com, thomas.lendacky@amd.com, hpa@zytor.com, asit.k.mallick@intel.com, tglx@linutronix.de, casey.schaufler@intel.com, dwmw@amazon.co.uk, longman9394@gmail.com, arjan@linux.intel.com, jcm@redhat.com, gregkh@linuxfoundation.org, jkosina@suse.cz In-Reply-To: <20181125185003.966801480@linutronix.de> References: <20181125185003.966801480@linutronix.de> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/pti] x86/speculation: Disable STIBP when enhanced IBRS is in use Git-Commit-ID: 34bce7c9690b1d897686aac89604ba7adc365556 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 34bce7c9690b1d897686aac89604ba7adc365556 Gitweb: https://git.kernel.org/tip/34bce7c9690b1d897686aac89604ba7adc365556 Author: Tim Chen AuthorDate: Sun, 25 Nov 2018 19:33:33 +0100 Committer: Thomas Gleixner CommitDate: Wed, 28 Nov 2018 11:57:05 +0100 x86/speculation: Disable STIBP when enhanced IBRS is in use If enhanced IBRS is active, STIBP is redundant for mitigating Spectre v2 user space exploits from hyperthread sibling. Disable STIBP when enhanced IBRS is used. Signed-off-by: Tim Chen Signed-off-by: Thomas Gleixner Reviewed-by: Ingo Molnar Cc: Peter Zijlstra Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Jiri Kosina Cc: Tom Lendacky Cc: Josh Poimboeuf Cc: Andrea Arcangeli Cc: David Woodhouse Cc: Andi Kleen Cc: Dave Hansen Cc: Casey Schaufler Cc: Asit Mallick Cc: Arjan van de Ven Cc: Jon Masters Cc: Waiman Long Cc: Greg KH Cc: Dave Stewart Cc: Kees Cook Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20181125185003.966801480@linutronix.de --- arch/x86/kernel/cpu/bugs.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index a1502bce9eb8..924cd06dd43b 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -321,6 +321,10 @@ static bool stibp_needed(void) if (spectre_v2_enabled == SPECTRE_V2_NONE) return false; + /* Enhanced IBRS makes using STIBP unnecessary. */ + if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED) + return false; + if (!boot_cpu_has(X86_FEATURE_STIBP)) return false; @@ -846,6 +850,9 @@ 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