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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,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 37DF9C04E87 for ; Wed, 15 May 2019 12:03:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0E53B20843 for ; Wed, 15 May 2019 12:03:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557921788; bh=XTbGk+eNjaxn2smx4uoCJQ9q2ZQ0CP6flhJiitiT/pE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=eclH57rg8TuIctKezNrEtkGx6mrh862cozt576Eou0IeCLY9NLoMXa59vxayvnrKP kbi9FQTCEJ9O8MXXcS0bb5x88xDQYRDqRtJx1nIBGxBMQ8xwjsnV9ERtZba14biPqE X6bf9y3wRguxTzQapfROHbRbf1r2NK16Y0l681QY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729857AbfEOLMo (ORCPT ); Wed, 15 May 2019 07:12:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:48198 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728929AbfEOLMn (ORCPT ); Wed, 15 May 2019 07:12:43 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 05ED120644; Wed, 15 May 2019 11:12:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557918762; bh=XTbGk+eNjaxn2smx4uoCJQ9q2ZQ0CP6flhJiitiT/pE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oVrTJ3cVX7E8558A9xOHqA3G1L25hGEJdDNgvCbW0pzrAwXnuWG3ZSnFEsXr2MNPb zNDbSxKMu7KB4gugPdSa9735vqkH1blMq4yCgkA3pj/DEQYG5+kxrU+3r4K2xE1sih Lh7+x9L+Oeu+BpF2iFbA6zaauTAJhsApIe+QAzME= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tim Chen , Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Andy Lutomirski , Linus Torvalds , Jiri Kosina , Tom Lendacky , Josh Poimboeuf , Andrea Arcangeli , David Woodhouse , Andi Kleen , Dave Hansen , Casey Schaufler , Asit Mallick , Arjan van de Ven , Jon Masters , Waiman Long , Dave Stewart , Kees Cook , Ben Hutchings Subject: [PATCH 4.4 205/266] x86/speculation: Disable STIBP when enhanced IBRS is in use Date: Wed, 15 May 2019 12:55:12 +0200 Message-Id: <20190515090729.892869678@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190515090722.696531131@linuxfoundation.org> References: <20190515090722.696531131@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tim Chen commit 34bce7c9690b1d897686aac89604ba7adc365556 upstream. 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 Link: https://lkml.kernel.org/r/20181125185003.966801480@linutronix.de Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/bugs.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -317,6 +317,10 @@ 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; @@ -761,6 +765,9 @@ static void __init l1tf_select_mitigatio 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