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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 08DADC3A59B for ; Fri, 30 Aug 2019 17:48:48 +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 CDB9923428 for ; Fri, 30 Aug 2019 17:48:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CDB9923428 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kaod.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38842 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i3l0w-0000UQ-P9 for qemu-devel@archiver.kernel.org; Fri, 30 Aug 2019 13:48:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58687) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i3kyW-0008AU-Er for qemu-devel@nongnu.org; Fri, 30 Aug 2019 13:46:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i3kyC-0003bM-0h for qemu-devel@nongnu.org; Fri, 30 Aug 2019 13:46:15 -0400 Received: from 8.mo68.mail-out.ovh.net ([46.105.74.219]:42943) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i3kyA-0003Vb-DV for qemu-devel@nongnu.org; Fri, 30 Aug 2019 13:45:54 -0400 Received: from player157.ha.ovh.net (unknown [10.109.160.232]) by mo68.mail-out.ovh.net (Postfix) with ESMTP id BAD3C140BB7 for ; Fri, 30 Aug 2019 19:45:50 +0200 (CEST) Received: from kaod.org (lns-bzn-46-82-253-208-248.adsl.proxad.net [82.253.208.248]) (Authenticated sender: groug@kaod.org) by player157.ha.ovh.net (Postfix) with ESMTPSA id 718B5938C274; Fri, 30 Aug 2019 17:45:45 +0000 (UTC) Date: Fri, 30 Aug 2019 19:45:43 +0200 From: Greg Kurz To: "Daniel P. =?UTF-8?B?QmVycmFuZ8Op?=" Message-ID: <20190830194543.6c1f5776@bahia.lan> In-Reply-To: <20190830163413.GH4674@redhat.com> References: <20190830161345.22436-1-lvivier@redhat.com> <20190830163413.GH4674@redhat.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Ovh-Tracer-Id: 6975512876504226155 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgeduvddrudeigedguddukecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfqggfjpdevjffgvefmvefgnecuuegrihhlohhuthemucehtddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 46.105.74.219 Subject: Re: [Qemu-devel] [Qemu-ppc] [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: , Cc: Laurent Vivier , 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, 30 Aug 2019 17:34:13 +0100 Daniel P. Berrang=C3=A9 wrote: > 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. > >=20 > > This happens because linux kernel needs to know the NUMA topology at > > start to be able to initialize the distance lookup table. > >=20 > > 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. > >=20 > > To avoid the kernel crash, do not allow to start pseries with empty > > nodes. >=20 > 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 ? >=20 I can try to grab an AIX image and give a try, but anyway this looks like a very big hammer to me... :-\ > > Signed-off-by: Laurent Vivier > > --- > > hw/ppc/spapr.c | 33 +++++++++++++++++++++++++++++++++ > > 1 file changed, 33 insertions(+) >=20 > Regards, > Daniel