From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:52608 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388227AbeHNUQW (ORCPT ); Tue, 14 Aug 2018 16:16:22 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josh Poimboeuf , Borislav Petkov , David Woodhouse Subject: [PATCH 4.18 79/79] x86/microcode: Allow late microcode loading with SMT disabled Date: Tue, 14 Aug 2018 19:17:38 +0200 Message-Id: <20180814171341.170088732@linuxfoundation.org> In-Reply-To: <20180814171336.799314117@linuxfoundation.org> References: <20180814171336.799314117@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josh Poimboeuf The kernel unnecessarily prevents late microcode loading when SMT is disabled. It should be safe to allow it if all the primary threads are online. Signed-off-by: Josh Poimboeuf Acked-by: Borislav Petkov Signed-off-by: David Woodhouse Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/microcode/core.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -509,12 +509,20 @@ static struct platform_device *microcode static int check_online_cpus(void) { - if (num_online_cpus() == num_present_cpus()) - return 0; + unsigned int cpu; - pr_err("Not all CPUs online, aborting microcode update.\n"); + /* + * Make sure all CPUs are online. It's fine for SMT to be disabled if + * all the primary threads are still online. + */ + for_each_present_cpu(cpu) { + if (topology_is_primary_thread(cpu) && !cpu_online(cpu)) { + pr_err("Not all CPUs online, aborting microcode update.\n"); + return -EINVAL; + } + } - return -EINVAL; + return 0; } static atomic_t late_cpus_in;