From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753951AbcCSJeJ (ORCPT ); Sat, 19 Mar 2016 05:34:09 -0400 Received: from [198.137.202.10] ([198.137.202.10]:58066 "EHLO terminus.zytor.com" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753513AbcCSJdt (ORCPT ); Sat, 19 Mar 2016 05:33:49 -0400 Date: Sat, 19 Mar 2016 02:31:02 -0700 From: tip-bot for Peter Zijlstra Message-ID: Cc: hpa@zytor.com, peterz@infradead.org, umgwanakikbuti@gmail.com, tglx@linutronix.de, mingo@kernel.org, linux-kernel@vger.kernel.org Reply-To: peterz@infradead.org, hpa@zytor.com, linux-kernel@vger.kernel.org, mingo@kernel.org, tglx@linutronix.de, umgwanakikbuti@gmail.com In-Reply-To: <20160318150538.611014173@infradead.org> References: <20160318150538.611014173@infradead.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86/topology: Fix Intel HT disable Git-Commit-ID: 63d1e995be455ae9196270eb4b789de21afd42ed X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 63d1e995be455ae9196270eb4b789de21afd42ed Gitweb: http://git.kernel.org/tip/63d1e995be455ae9196270eb4b789de21afd42ed Author: Peter Zijlstra AuthorDate: Fri, 18 Mar 2016 16:03:48 +0100 Committer: Thomas Gleixner CommitDate: Sat, 19 Mar 2016 10:26:40 +0100 x86/topology: Fix Intel HT disable As per the comment in the code; due to BIOS it is sometimes impossible to know if there actually are smp siblings until the machine is fully enumerated. So we rather overestimate the number of possible packages. Fixes: 1f12e32f4cd5 ("x86/topology: Create logical package id") Signed-off-by: Peter Zijlstra (Intel) Cc: aherrmann@suse.com Cc: jencce.kernel@gmail.com Cc: bp@alien8.de Cc: Mike Galbraith Link: http://lkml.kernel.org/r/20160318150538.611014173@infradead.org Signed-off-by: Thomas Gleixner --- arch/x86/kernel/smpboot.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 64b669d..81e6a43 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -312,8 +312,21 @@ static void __init smp_init_package_map(void) /* * Today neither Intel nor AMD support heterogenous systems. That * might change in the future.... + * + * While ideally we'd want '* smp_num_siblings' in the below @ncpus + * computation, this won't actually work since some Intel BIOSes + * report inconsistent HT data when they disable HT. + * + * In particular, they reduce the APIC-IDs to only include the cores, + * but leave the CPUID topology to say there are (2) siblings. + * This means we don't know how many threads there will be until + * after the APIC enumeration. + * + * By not including this we'll sometimes over-estimate the number of + * logical packages by the amount of !present siblings, but this is + * still better than MAX_LOCAL_APIC. */ - ncpus = boot_cpu_data.x86_max_cores * smp_num_siblings; + ncpus = boot_cpu_data.x86_max_cores; __max_logical_packages = DIV_ROUND_UP(nr_cpu_ids, ncpus); /*