On Fri, 16 Aug 2019 14:07:50 -0300 Eduardo Habkost <ehabk...@redhat.com> wrote:
> 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 176d2cda0dee ("i386/cpu: Consolidate die-id validity in smp > context") > Signed-off-by: Eduardo Habkost <ehabk...@redhat.com> Reviewed-by: Igor Mammedov <imamm...@redhat.com> > --- > Changes v1 -> v2: > * v1 was "pc: Don't make CPU properties mandatory unless necessary" > * Make only die-id optional (Igor Mammedov) > --- > hw/i386/pc.c | 8 ++++++ > tests/acceptance/pc_cpu_hotplug_props.py | 35 ++++++++++++++++++++++++ > 2 files changed, 43 insertions(+) > create mode 100644 tests/acceptance/pc_cpu_hotplug_props.py > > diff --git a/hw/i386/pc.c b/hw/i386/pc.c > index 3ab4bcb3ca..9c3f6ae828 100644 > --- a/hw/i386/pc.c > +++ b/hw/i386/pc.c > @@ -2406,6 +2406,14 @@ 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; > diff --git a/tests/acceptance/pc_cpu_hotplug_props.py > b/tests/acceptance/pc_cpu_hotplug_props.py > new file mode 100644 > index 0000000000..08b7e632c6 > --- /dev/null > +++ b/tests/acceptance/pc_cpu_hotplug_props.py > @@ -0,0 +1,35 @@ > +# > +# Ensure CPU die-id can be omitted on -device > +# > +# Copyright (c) 2019 Red Hat Inc > +# > +# Author: > +# Eduardo Habkost <ehabk...@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)
