From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752179AbcEGINv (ORCPT ); Sat, 7 May 2016 04:13:51 -0400 Received: from terminus.zytor.com ([198.137.202.10]:46004 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751018AbcEGINa (ORCPT ); Sat, 7 May 2016 04:13:30 -0400 Date: Sat, 7 May 2016 01:12:39 -0700 From: tip-bot for Thomas Gleixner Message-ID: Cc: david.vrabel@citrix.com, hpa@zytor.com, peterz@infradead.org, joseph.salisbury@canonical.com, linux-kernel@vger.kernel.org, boris.ostrovsky@oracle.com, tglx@linutronix.de, mingo@kernel.org Reply-To: linux-kernel@vger.kernel.org, tglx@linutronix.de, boris.ostrovsky@oracle.com, mingo@kernel.org, joseph.salisbury@canonical.com, peterz@infradead.org, david.vrabel@citrix.com, hpa@zytor.com In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86/topology: Handle CPUID bogosity gracefully Git-Commit-ID: 56402d63eefe22179f7311a51ff2094731420406 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: 56402d63eefe22179f7311a51ff2094731420406 Gitweb: http://git.kernel.org/tip/56402d63eefe22179f7311a51ff2094731420406 Author: Thomas Gleixner AuthorDate: Fri, 6 May 2016 20:48:16 +0200 Committer: Thomas Gleixner CommitDate: Sat, 7 May 2016 10:06:55 +0200 x86/topology: Handle CPUID bogosity gracefully Joseph reported that a XEN guest dies with a division by 0 in the package topology setup code. This happens if cpu_info.x86_max_cores is zero. Handle that case and emit a warning. This does not fix the underlying XEN bug, but makes the code more robust. Reported-and-tested-by: Joseph Salisbury Cc: Peter Zijlstra Cc: Boris Ostrovsky Cc: David Vrabel Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1605062046270.3540@nanos Signed-off-by: Thomas Gleixner --- arch/x86/kernel/smpboot.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index a2065d3..0e4329e 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -332,6 +332,11 @@ static void __init smp_init_package_map(void) * primary cores. */ ncpus = boot_cpu_data.x86_max_cores; + if (!ncpus) { + pr_warn("x86_max_cores == zero !?!?"); + ncpus = 1; + } + __max_logical_packages = DIV_ROUND_UP(total_cpus, ncpus); /*