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

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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 176d2cda0d ("i386/cpu: Consolidate die-id validity in smp context")
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20190816170750.23910-1-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
This commit is contained in:
Eduardo Habkost 2019-08-16 14:07:50 -03:00
parent 23d9cff489
commit fea374e7c8
2 changed files with 43 additions and 0 deletions
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8
hw/i386/pc.c
View File

@ -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;

35
tests/acceptance/pc_cpu_hotplug_props.py Normal file
View File

@ -0,0 +1,35 @@
#
# 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)