From patchwork Thu May 20 09:19:06 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 445744 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=-19.1 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 111F5C43460 for ; Thu, 20 May 2021 09:51:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E14BD61C42 for ; Thu, 20 May 2021 09:51:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233989AbhETJxQ (ORCPT ); Thu, 20 May 2021 05:53:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:54976 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234158AbhETJvP (ORCPT ); Thu, 20 May 2021 05:51:15 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A556F61493; Thu, 20 May 2021 09:35:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621503343; bh=UBIbv7kBYow8gctLkfl3Zh8V/qteibdTpqze7JkSdNg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ja0D4hhYU3bVLpXoAWuBxmgehWtJbMFl3ZAvPOPavSJdCjXL6/fFH92QwIhbwQZIL 84C4qRnJyA526Cmf17cER5i4fjjhxfmHoDoRLmxlWxpX3Oh0pRneB2pSAMW8HnVAGc FS6sWdm2jlHw+wFgLaLWMJItGX3QG2syBE3SubQA= 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 4.19 177/425] x86/microcode: Check for offline CPUs before requesting new microcode Date: Thu, 20 May 2021 11:19:06 +0200 Message-Id: <20210520092137.253245602@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210520092131.308959589@linuxfoundation.org> References: <20210520092131.308959589@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 a96091d44a45..eab4de387ce6 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -627,16 +627,16 @@ 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);