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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68A53C433EF for ; Tue, 12 Jul 2022 18:57:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234842AbiGLS5a (ORCPT ); Tue, 12 Jul 2022 14:57:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40318 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234954AbiGLS4y (ORCPT ); Tue, 12 Jul 2022 14:56:54 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EC8ACD31E3; Tue, 12 Jul 2022 11:46:57 -0700 (PDT) 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 ams.source.kernel.org (Postfix) with ESMTPS id 4F622B81BBB; Tue, 12 Jul 2022 18:46:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79D30C3411C; Tue, 12 Jul 2022 18:46:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1657651615; bh=E1G/sj44DQ1PBjU34Ar46hxoaFI0v+72xBumAP9AX4o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z+UmkDn/GTPDFyyXGogJU8S+/AYJwK/w56EnAmDDv2dYW8OBkk3pllDJOIoK7DAdZ IULUHHc+iQ3OrAJ/ubJBN69a8ovSeIHeb8cQfKjECdxX6gyrNe86RtEWAuRCo4R00h Hs3mHiD88NvHLXWf5KPBBBHY3wGZ6/DfsbfSDEs0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josh Poimboeuf , Borislav Petkov , Thadeu Lima de Souza Cascardo , Ben Hutchings Subject: [PATCH 5.10 109/130] x86/bugs: Do IBPB fallback check only once Date: Tue, 12 Jul 2022 20:39:15 +0200 Message-Id: <20220712183251.505316520@linuxfoundation.org> X-Mailer: git-send-email 2.37.0 In-Reply-To: <20220712183246.394947160@linuxfoundation.org> References: <20220712183246.394947160@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Josh Poimboeuf commit 0fe4aeea9c01baabecc8c3afc7889c809d939bc2 upstream. When booting with retbleed=auto, if the kernel wasn't built with CONFIG_CC_HAS_RETURN_THUNK, the mitigation falls back to IBPB. Make sure a warning is printed in that case. The IBPB fallback check is done twice, but it really only needs to be done once. Signed-off-by: Josh Poimboeuf Signed-off-by: Borislav Petkov Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/bugs.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -847,18 +847,13 @@ static void __init retbleed_select_mitig case RETBLEED_CMD_AUTO: default: if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || - boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) { - - if (IS_ENABLED(CONFIG_RETPOLINE) && - IS_ENABLED(CONFIG_CC_HAS_RETURN_THUNK)) - retbleed_mitigation = RETBLEED_MITIGATION_UNRET; - else - retbleed_mitigation = RETBLEED_MITIGATION_IBPB; - } + boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) + retbleed_mitigation = RETBLEED_MITIGATION_UNRET; /* - * The Intel mitigation (IBRS) was already selected in - * spectre_v2_select_mitigation(). + * The Intel mitigation (IBRS or eIBRS) was already selected in + * spectre_v2_select_mitigation(). 'retbleed_mitigation' will + * be set accordingly below. */ break;