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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 93582C2B9F7 for ; Wed, 12 May 2021 16:42:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3BEB4611BF for ; Wed, 12 May 2021 16:42:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241897AbhELQjz (ORCPT ); Wed, 12 May 2021 12:39:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:48578 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234888AbhELQcJ (ORCPT ); Wed, 12 May 2021 12:32:09 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1D23A61C29; Wed, 12 May 2021 15:58:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620835107; bh=FI0ddjr4pAW+VbWpjQOnTlgr/OLi7wrRaVCvP3n3syU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XxvE8QXY19xruB0RE03c6ZlgQToO14MvY1L921IvVQI/rYLH+V1mRFGSrqVCxTIzu ECyn6nZvwQqZh5CyttUpZ2JlRrPqC4ZwqKSvTkdAVc28d0/tHp1VPUQ562TrySNMaB em7JoD6xImkkCXZlqZ0UqmFbNiBLUmCiKr88s4Gg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Otavio Pontes , Borislav Petkov , Tony Luck , Ashok Raj , Sasha Levin Subject: [PATCH 5.12 211/677] x86/microcode: Check for offline CPUs before requesting new microcode Date: Wed, 12 May 2021 16:44:17 +0200 Message-Id: <20210512144844.251682214@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210512144837.204217980@linuxfoundation.org> References: <20210512144837.204217980@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: stable@vger.kernel.org From: Otavio Pontes [ Upstream commit 7189b3c11903667808029ec9766a6e96de5012a5 ] Currently, the late microcode loading mechanism checks whether any CPUs are offlined, and, in such a case, aborts the load attempt. However, this must be done before the kernel caches new microcode from the filesystem. Otherwise, when offlined CPUs are onlined later, those cores are going to be updated through the CPU hotplug notifier callback with the new microcode, while CPUs previously onine will continue to run with the older microcode. For example: Turn off one core (2 threads): echo 0 > /sys/devices/system/cpu/cpu3/online echo 0 > /sys/devices/system/cpu/cpu1/online Install the ucode fails because a primary SMT thread is offline: cp intel-ucode/06-8e-09 /lib/firmware/intel-ucode/ echo 1 > /sys/devices/system/cpu/microcode/reload bash: echo: write error: Invalid argument Turn the core back on echo 1 > /sys/devices/system/cpu/cpu3/online echo 1 > /sys/devices/system/cpu/cpu1/online cat /proc/cpuinfo |grep microcode microcode : 0x30 microcode : 0xde microcode : 0x30 microcode : 0xde The rationale for why the update is aborted when at least one primary thread is offline is because even if that thread is soft-offlined and idle, it will still have to participate in broadcasted MCE's synchronization dance or enter SMM, and in both examples it will execute instructions so it better have the same microcode revision as the other cores. [ bp: Heavily edit and extend commit message with the reasoning behind all this. ] Fixes: 30ec26da9967 ("x86/microcode: Do not upload microcode if CPUs are offline") Signed-off-by: Otavio Pontes Signed-off-by: Borislav Petkov Reviewed-by: Tony Luck Acked-by: Ashok Raj Link: https://lkml.kernel.org/r/20210319165515.9240-2-otavio.pontes@intel.com Signed-off-by: Sasha Levin --- arch/x86/kernel/cpu/microcode/core.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c index b935e1b5f115..6a6318e9590c 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -629,16 +629,16 @@ static ssize_t reload_store(struct device *dev, if (val != 1) return size; - tmp_ret = microcode_ops->request_microcode_fw(bsp, µcode_pdev->dev, true); - if (tmp_ret != UCODE_NEW) - return size; - get_online_cpus(); ret = check_online_cpus(); if (ret) goto put; + tmp_ret = microcode_ops->request_microcode_fw(bsp, µcode_pdev->dev, true); + if (tmp_ret != UCODE_NEW) + goto put; + mutex_lock(µcode_mutex); ret = microcode_reload_late(); mutex_unlock(µcode_mutex); -- 2.30.2