From mboxrd@z Thu Jan 1 00:00:00 1970 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=-5.2 required=3.0 tests=FROM_EXCESS_BASE64, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 5B394C3A59B for ; Fri, 30 Aug 2019 16:38:54 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2EEF02087F for ; Fri, 30 Aug 2019 16:38:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2EEF02087F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:36724 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i3jvJ-0004bK-AU for qemu-devel@archiver.kernel.org; Fri, 30 Aug 2019 12:38:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:42516) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i3jqy-0000xl-9t for qemu-devel@nongnu.org; Fri, 30 Aug 2019 12:34:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i3jqv-0004mq-1D for qemu-devel@nongnu.org; Fri, 30 Aug 2019 12:34:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39182) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i3jqu-0004fn-R6; Fri, 30 Aug 2019 12:34:20 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 737EF3001FEB; Fri, 30 Aug 2019 16:34:18 +0000 (UTC) Received: from redhat.com (ovpn-112-43.ams2.redhat.com [10.36.112.43]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C6DDD60BF7; Fri, 30 Aug 2019 16:34:16 +0000 (UTC) Date: Fri, 30 Aug 2019 17:34:13 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Laurent Vivier Message-ID: <20190830163413.GH4674@redhat.com> References: <20190830161345.22436-1-lvivier@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190830161345.22436-1-lvivier@redhat.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Fri, 30 Aug 2019 16:34:18 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH] pseries: do not allow memory-less/cpu-less NUMA node X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org, David Gibson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Aug 30, 2019 at 06:13:45PM +0200, Laurent Vivier wrote: > When we hotplug a CPU on memory-less/cpu-less node, the linux kernel > crashes. > > This happens because linux kernel needs to know the NUMA topology at > start to be able to initialize the distance lookup table. > > On pseries, the topology is provided by the firmware via the existing > CPUs and memory information. Thus a node without memory and CPU cannot be > discovered by the kernel. > > To avoid the kernel crash, do not allow to start pseries with empty > nodes. This describes one possible guest OS. Is there any reasonable chance that a non-Linux guest might be able to handle this situation correctly, or do you expect any guest to have the same restriction ? > Signed-off-by: Laurent Vivier > --- > hw/ppc/spapr.c | 33 +++++++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|