From patchwork Wed May 12 14:44:36 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 438607 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 39495C4360C for ; Wed, 12 May 2021 15:29:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1152561C1A for ; Wed, 12 May 2021 15:29:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233227AbhELP25 (ORCPT ); Wed, 12 May 2021 11:28:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:57874 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232512AbhELPW1 (ORCPT ); Wed, 12 May 2021 11:22:27 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 86678619AD; Wed, 12 May 2021 15:09:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620832161; bh=o5oqbkMVJmjlAf0Eu5IO1+PBt/2w4iV8hZ4r1VQk++g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fNTtQZcqhPdrVeAv9heRWFfzfRmXRir/GJdzZvjpwMNsxFNTCpOWIWb3qEolmBY0i zmDrBZe+TL+tYKZuqFIwKKK4vzGxfIJctysY+nX8sIzGhQ5ku11KvFGw15krBUP9kI 2I1HpoiHdzUeUzZypsVrf5bX9kJbsiJp+tNtHOJc= 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 5.10 166/530] x86/microcode: Check for offline CPUs before requesting new microcode Date: Wed, 12 May 2021 16:44:36 +0200 Message-Id: <20210512144825.293147780@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210512144819.664462530@linuxfoundation.org> References: <20210512144819.664462530@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 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 ec6f0415bc6d..bbbd248fe913 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);