Commit fea374e7 authored by Eduardo Habkost's avatar Eduardo Habkost
Browse files

pc: Don't make die-id mandatory unless necessary 

We have this issue reported when using libvirt to hotplug CPUs:
https://bugzilla.redhat.com/show_bug.cgi?id=1741451



Basically, libvirt is not copying die-id from
query-hotpluggable-cpus, but die-id is now mandatory.

We could blame libvirt and say it is not following the documented
interface, because we have this buried in the QAPI schema
documentation:

> Note: currently there are 5 properties that could be present
> but management should be prepared to pass through other
> properties with device_add command to allow for future
> interface extension. This also requires the filed names to be kept in
> sync with the properties passed to -device/device_add.

But I don't think this would be reasonable from us.  We can just
make QEMU more flexible and let die-id to be omitted when there's
no ambiguity.  This will allow us to keep compatibility with
existing libvirt versions.

Test case included to ensure we don't break this again.

Fixes: commit 176d2cda ("i386/cpu: Consolidate die-id validity in smp context")
Signed-off-by: default avatarEduardo Habkost <ehabkost@redhat.com>
Message-Id: <20190816170750.23910-1-ehabkost@redhat.com>
Signed-off-by: default avatarEduardo Habkost <ehabkost@redhat.com>
parent 23d9cff4

hw/i386/pc.c

+8 −0
Original line number Diff line number Diff line
@@ -2421,6 +2421,14 @@ static void pc_cpu_pre_plug(HotplugHandler *hotplug_dev, 
        int max_socket = (ms->smp.max_cpus - 1) /

                                smp_threads / smp_cores / pcms->smp_dies;



        /*

         * die-id was optional in QEMU 4.0 and older, so keep it optional

         * if there's only one die per socket.

         */

        if (cpu->die_id < 0 && pcms->smp_dies == 1) {

            cpu->die_id = 0;

        }



        if (cpu->socket_id < 0) {

            error_setg(errp, "CPU socket-id is not set");

            return;

tests/acceptance/pc_cpu_hotplug_props.py

0 → 100644
+35 −0
Original line number Diff line number Diff line 
#

# Ensure CPU die-id can be omitted on -device

#

#  Copyright (c) 2019 Red Hat Inc

#

# Author:

#  Eduardo Habkost <ehabkost@redhat.com>

#

# This library is free software; you can redistribute it and/or

# modify it under the terms of the GNU Lesser General Public

# License as published by the Free Software Foundation; either

# version 2 of the License, or (at your option) any later version.

#

# This library is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

# Lesser General Public License for more details.

#

# You should have received a copy of the GNU Lesser General Public

# License along with this library; if not, see <http://www.gnu.org/licenses/>.

#



from avocado_qemu import Test



class OmittedCPUProps(Test):

    """

    :avocado: tags=arch:x86_64

    """

    def test_no_die_id(self):

        self.vm.add_args('-nodefaults', '-S')

        self.vm.add_args('-smp', '1,sockets=2,cores=2,threads=2,maxcpus=8')

        self.vm.add_args('-cpu', 'qemu64')

        self.vm.add_args('-device', 'qemu64-x86_64-cpu,socket-id=1,core-id=0,thread-id=0')

        self.vm.launch()

        self.assertEquals(len(self.vm.command('query-cpus')), 2)