From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752542AbeB1KbS (ORCPT ); Wed, 28 Feb 2018 05:31:18 -0500 Received: from mail.skyhub.de ([5.9.137.197]:37154 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752472AbeB1K3S (ORCPT ); Wed, 28 Feb 2018 05:29:18 -0500 From: Borislav Petkov To: X86 ML Cc: Arjan Van De Ven , Ashok Raj , Tom Lendacky , LKML Subject: [PATCH 4/7] x86/microcode: Do not upload microcode if CPUs are offline Date: Wed, 28 Feb 2018 11:28:43 +0100 Message-Id: <20180228102846.13447-5-bp@alien8.de> X-Mailer: git-send-email 2.13.0 In-Reply-To: <20180228102846.13447-1-bp@alien8.de> References: <20180228102846.13447-1-bp@alien8.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ashok Raj Avoid loading microcode if any of the CPUs are offline, and issue a warning. Having different microcode revisions on the system at any time is outright dangerous. Signed-off-by: Ashok Raj Cc: x86-ml Link: http://lkml.kernel.org/r/1519352533-15992-4-git-send-email-ashok.raj@intel.com [ Massage it. ] Signed-off-by: Borislav Petkov --- arch/x86/kernel/cpu/microcode/core.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c index 63370651e376..fa32cb3dcca5 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -486,6 +486,16 @@ static void __exit microcode_dev_exit(void) /* fake device for request_firmware */ static struct platform_device *microcode_pdev; +static int check_online_cpus(void) +{ + if (num_online_cpus() == num_present_cpus()) + return 0; + + pr_err("Not all CPUs online, aborting microcode update.\n"); + + return -EINVAL; +} + static enum ucode_state reload_for_cpu(int cpu) { struct ucode_cpu_info *uci = ucode_cpu_info + cpu; @@ -519,7 +529,13 @@ static ssize_t reload_store(struct device *dev, return size; get_online_cpus(); + + ret = check_online_cpus(); + if (ret) + goto put; + mutex_lock(µcode_mutex); + for_each_online_cpu(cpu) { tmp_ret = reload_for_cpu(cpu); if (tmp_ret > UCODE_NFOUND) { @@ -538,6 +554,8 @@ static ssize_t reload_store(struct device *dev, microcode_check(); mutex_unlock(µcode_mutex); + +put: put_online_cpus(); if (!ret) -- 2.13.0