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 37843C433EF for ; Tue, 12 Jul 2022 18:56:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234726AbiGLS4y (ORCPT ); Tue, 12 Jul 2022 14:56:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57444 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234521AbiGLS4V (ORCPT ); Tue, 12 Jul 2022 14:56:21 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8DD94EB03B; Tue, 12 Jul 2022 11:46:43 -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 dfw.source.kernel.org (Postfix) with ESMTPS id E748560A5A; Tue, 12 Jul 2022 18:46:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D70F4C3411C; Tue, 12 Jul 2022 18:46:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1657651602; bh=MwuU+xseDp9KXWFIrzDY8KulQryfkv/g26Hg1/eETvA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tzctrIWzScPD9gGHbJWX0AlVLH+GYPGBRDQbsf22kJoobP1T7XYpLWKpm/lThR9fT D1t3aLs5hDkLeEUMQuPOc2hp4K1n55pXpafonV1cT6CY/Q4hz5KONGcMY0O6FEvNTX DYA1gSkLJ27jFT0+12t4CRlRQmceERt5ryjHMp5w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thadeu Lima de Souza Cascardo , Borislav Petkov , Ben Hutchings Subject: [PATCH 5.10 127/130] x86/bugs: Do not enable IBPB-on-entry when IBPB is not supported Date: Tue, 12 Jul 2022 20:39:33 +0200 Message-Id: <20220712183252.325226631@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: Thadeu Lima de Souza Cascardo commit 2259da159fbe5dba8ac00b560cf00b6a6537fa18 upstream. There are some VM configurations which have Skylake model but do not support IBPB. In those cases, when using retbleed=ibpb, userspace is going to be killed and kernel is going to panic. If the CPU does not support IBPB, warn and proceed with the auto option. Also, do not fallback to IBPB on AMD/Hygon systems if it is not supported. Fixes: 3ebc17006888 ("x86/bugs: Add retbleed=ibpb") Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Borislav Petkov Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/bugs.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -821,7 +821,10 @@ static void __init retbleed_select_mitig break; case RETBLEED_CMD_IBPB: - if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY)) { + if (!boot_cpu_has(X86_FEATURE_IBPB)) { + pr_err("WARNING: CPU does not support IBPB.\n"); + goto do_cmd_auto; + } else if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY)) { retbleed_mitigation = RETBLEED_MITIGATION_IBPB; } else { pr_err("WARNING: kernel not compiled with CPU_IBPB_ENTRY.\n"); @@ -836,7 +839,7 @@ do_cmd_auto: boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) { if (IS_ENABLED(CONFIG_CPU_UNRET_ENTRY)) retbleed_mitigation = RETBLEED_MITIGATION_UNRET; - else if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY)) + else if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY) && boot_cpu_has(X86_FEATURE_IBPB)) retbleed_mitigation = RETBLEED_MITIGATION_IBPB; }