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[2620:137:e000::1:20]) by mx.google.com with ESMTP id n17-20020a170902d2d100b00198d701adb4si3329949plc.615.2023.02.20.10.40.16; Mon, 20 Feb 2023 10:40:29 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b="uqE9+1R/"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231814AbjBTS1X (ORCPT + 99 others); Mon, 20 Feb 2023 13:27:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41236 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229885AbjBTS1W (ORCPT ); Mon, 20 Feb 2023 13:27:22 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 343A71C31A; Mon, 20 Feb 2023 10:27:21 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A781860F00; Mon, 20 Feb 2023 18:27:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5FFABC4339B; Mon, 20 Feb 2023 18:27:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1676917640; bh=T7ZxLDOEHL5a48unqqdISt58VJOeJ4E3/WLn0nVRKCc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=uqE9+1R/bBNbWjA+oKlDucXB7DEGP9lhZkLY/MFrrjkLOemujnpYEywdzT2fT3Vxs bsbanDWV6wca2uXqpo5RtprA1GqJW91apcJeFNcL/5K6srwBSa1MxMuYXA02Y+dq79 mZxBvzDa9WbpU0AXUqn0TmmsbpXJA3SJhUAcyay5T7Zf9cAP6HfBTyQ+hzXhYpssgx exT1bItyrpzsWmCuZjz8luhWCeNiBFc/6/UwBIoctZ+P5fS32pz0VkHkegg6mOZW5/ JgA9M+MXtfFRdiM/uX0+QPLKY8+rt3qSR5witakoCgmE5YSyONhR78CcOunQnRMuzZ aC0vt5DD6alBw== Date: Mon, 20 Feb 2023 10:27:17 -0800 From: Josh Poimboeuf To: KP Singh Cc: Borislav Petkov , linux-kernel@vger.kernel.org, pjt@google.com, evn@google.com, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, peterz@infradead.org, pawan.kumar.gupta@linux.intel.com, kim.phillips@amd.com, alexandre.chartre@oracle.com, daniel.sneddon@linux.intel.com, =?utf-8?b?Sm9zw6k=?= Oliveira , Rodrigo Branco , Alexandra Sandulescu , Jim Mattson , stable@vger.kernel.org Subject: [PATCH] x86/bugs: Allow STIBP with IBRS Message-ID: <20230220182717.uzrym2gtavlbjbxo@treble> References: <20230220120127.1975241-1-kpsingh@kernel.org> <20230220121350.aidsipw3kd4rsyss@treble> <20230220163442.7fmaeef3oqci4ee3@treble> <20230220175929.2laflfb2met6y3kc@treble> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-7.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1758376419465202075?= X-GMAIL-MSGID: =?utf-8?q?1758376419465202075?= IBRS is only enabled in kernel space. Since it's not enabled in user space, user space isn't protected from indirect branch prediction attacks from a sibling CPU thread. Allow STIBP to be enabled to protect against such attacks. Fixes: 7c693f54c873 ("x86/speculation: Add spectre_v2=ibrs option to support Kernel IBRS") Reported-by: José Oliveira Reported-by: Rodrigo Branco Signed-off-by: Josh Poimboeuf --- arch/x86/kernel/cpu/bugs.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 85168740f76a..b97c0d28e573 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1124,14 +1124,19 @@ spectre_v2_parse_user_cmdline(void) return SPECTRE_V2_USER_CMD_AUTO; } -static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode) +static inline bool spectre_v2_in_eibrs_mode(enum spectre_v2_mitigation mode) { - return mode == SPECTRE_V2_IBRS || - mode == SPECTRE_V2_EIBRS || + return mode == SPECTRE_V2_EIBRS || mode == SPECTRE_V2_EIBRS_RETPOLINE || mode == SPECTRE_V2_EIBRS_LFENCE; } +static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode) +{ + return spectre_v2_in_eibrs_mode(mode) || + mode == SPECTRE_V2_IBRS; +} + static void __init spectre_v2_user_select_mitigation(void) { @@ -1194,12 +1199,12 @@ spectre_v2_user_select_mitigation(void) } /* - * If no STIBP, IBRS or enhanced IBRS is enabled, or SMT impossible, + * If no STIBP, enhanced IBRS is enabled, or SMT impossible, * STIBP is not required. */ if (!boot_cpu_has(X86_FEATURE_STIBP) || !smt_possible || - spectre_v2_in_ibrs_mode(spectre_v2_enabled)) + spectre_v2_in_eibrs_mode(spectre_v2_enabled)) return; /* @@ -2327,9 +2332,6 @@ static ssize_t mmio_stale_data_show_state(char *buf) static char *stibp_state(void) { - if (spectre_v2_in_ibrs_mode(spectre_v2_enabled)) - return ""; - switch (spectre_v2_user_stibp) { case SPECTRE_V2_USER_NONE: return ", STIBP: disabled";