From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54208) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dDDzV-00015k-K7 for qemu-devel@nongnu.org; Tue, 23 May 2017 13:53:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dDDzQ-0000Qu-O4 for qemu-devel@nongnu.org; Tue, 23 May 2017 13:53:05 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:38215 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dDDzQ-0000QZ-Hk for qemu-devel@nongnu.org; Tue, 23 May 2017 13:53:00 -0400 Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v4NHnA9a056314 for ; Tue, 23 May 2017 13:52:59 -0400 Received: from e24smtp04.br.ibm.com (e24smtp04.br.ibm.com [32.104.18.25]) by mx0b-001b2d01.pphosted.com with ESMTP id 2amreh4f4w-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 23 May 2017 13:52:59 -0400 Received: from localhost by e24smtp04.br.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 23 May 2017 14:52:57 -0300 References: <20170523111812.13469-1-lvivier@redhat.com> From: Daniel Henrique Barboza Date: Tue, 23 May 2017 14:52:54 -0300 MIME-Version: 1.0 In-Reply-To: <20170523111812.13469-1-lvivier@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Message-Id: <7509d665-566e-2570-9936-44a04bad75fe@linux.vnet.ibm.com> Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH 0/4] spapr: disable hotplugging without OS List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Laurent Vivier , David Gibson Cc: Thomas Huth , qemu-ppc@nongnu.org, qemu-devel@nongnu.org, Michael Roth Hi Laurent, This is an interesting patch series. I've been working in the last weeks in the DRC migration, mainly to solve the problem in which a hot CPU unplug will not succeed after a migration if the CPU was hotplugged in the source. The problem happened when migrating with virsh because Libvirt hotplugs the CPU in both source and target, and the DRC state of the hotplugged after the migration is inconsistent. This series solves the issue by preventing it from happening in the first place. Of course that migrating DRC states has other uses (pending unplug operations during a migration, for example) so both patch series can coexist. One possible issue I see with this series is that it breaks Libvirt migration entirely if a CPU/mem hotplug happens in the target. With your series applied the migration fails before start with: # ./virsh -c 'qemu:///system' migrate --live --domain dhb_ub1704_nfs --desturi qemu+ssh://target_ip/system --timeout 60 --verbose error: internal error: unable to execute QEMU command 'device_add': CPU hotplug not supported without OS Note that I say "possible issue" because, although I believe we do not want to break Libvirt if possible, I also believe that we need to think about what makes sense in QEMU first. Thanks, Daniel On 05/23/2017 08:18 AM, Laurent Vivier wrote: > If the OS is not started, QEMU sends an event to the OS > that is lost and cannot be recovered. An unplug is not > able to restore QEMU in a coherent state. > So, while the OS is not started, disable CPU and memory hotplug. > We use option vector 6 to know if the OS is started > > This series moves error checking for memory hotplug > in a pre_plug function, and introduces the option > vector 6 management. It also revert previous > fix which was not really fixing the hotplug problem > when the OS is not running. > > Laurent Vivier (4): > spapr: add pre_plug function for memory > spapr: add option vector 6 > spapr: disable hotplugging without OS > Revert "spapr: fix memory hot-unplugging" > > hw/ppc/spapr.c | 103 ++++++++++++++++++++++++++++++++++++-------- > hw/ppc/spapr_drc.c | 20 ++------- > hw/ppc/spapr_hcall.c | 5 ++- > hw/ppc/spapr_ovec.c | 8 ++++ > include/hw/ppc/spapr.h | 2 + > include/hw/ppc/spapr_drc.h | 1 - > include/hw/ppc/spapr_ovec.h | 7 +++ > 7 files changed, 109 insertions(+), 37 deletions(-) >