On Wed, Jan 05, 2022 at 03:49:12PM +0100, Laurent Vivier wrote: > On 05/01/2022 13:38, Daniel P. Berrangé wrote: > > The -device JSON syntax impl leaks a reference on the created > > DeviceState instance. As a result when you hot-unplug the > > device, the device_finalize method won't be called and thus > > it will fail to emit the required DEVICE_DELETED event. > > > > A 'json-cli' feature was previously added against the > > 'device_add' QMP command QAPI schema to indicated to mgmt > > apps that -device supported JSON syntax. Given the hotplug > > bug that feature flag is no unusable for its purpose, so > > Not sure to understand: do you mean "now unusable"?
An application wants to known whether QEMU can support JSON syntax with -device. If they look for the 'json-cli' feature as a witness, they'll end up using JSON with QEMU 6.2 which is giving them broken hotplug. This is unusable for any non-trivial use cases. So we need a new witness to indicate whether JSON is viable with -device, that only the newly fixed QEMU will report. > > > we add a new 'json-cli-hotplug' feature to indicate the > > -device supports JSON without breaking hotplug. > > > > Fixes: https://gitlab.com/qemu-project/qemu/-/issues/802 > > Signed-off-by: Daniel P. Berrangé <berra...@redhat.com> > > --- > > qapi/qdev.json | 5 ++++- > > softmmu/vl.c | 4 +++- > > tests/qtest/device-plug-test.c | 19 +++++++++++++++++++ > > 3 files changed, 26 insertions(+), 2 deletions(-) > > > > diff --git a/qapi/qdev.json b/qapi/qdev.json > > index 69656b14df..26cd10106b 100644 > > --- a/qapi/qdev.json > > +++ b/qapi/qdev.json > > @@ -44,6 +44,9 @@ > > # @json-cli: If present, the "-device" command line option supports JSON > > # syntax with a structure identical to the arguments of this > > # command. > > +# @json-cli-hotplug: If present, the "-device" command line option > > supports JSON > > +# syntax without the reference counting leak that broke > > +# hot-unplug > > # > > # Notes: > > # > > @@ -74,7 +77,7 @@ > > { 'command': 'device_add', > > 'data': {'driver': 'str', '*bus': 'str', '*id': 'str'}, > > 'gen': false, # so we can get the additional arguments > > - 'features': ['json-cli'] } > > + 'features': ['json-cli', 'json-cli-hotplug'] } > > ## > > # @device_del: > > diff --git a/softmmu/vl.c b/softmmu/vl.c > > index d9e4c619d3..b1fc7da104 100644 > > --- a/softmmu/vl.c > > +++ b/softmmu/vl.c > > @@ -2684,6 +2684,7 @@ static void qemu_create_cli_devices(void) > > qemu_opts_foreach(qemu_find_opts("device"), > > device_init_func, NULL, &error_fatal); > > QTAILQ_FOREACH(opt, &device_opts, next) { > > + DeviceState *dev; > > loc_push_restore(&opt->loc); > > /* > > * TODO Eventually we should call qmp_device_add() here to make > > sure it > > @@ -2692,7 +2693,8 @@ static void qemu_create_cli_devices(void) > > * from the start, so call qdev_device_add_from_qdict() directly > > for > > * now. > > */ > > - qdev_device_add_from_qdict(opt->opts, true, &error_fatal); > > + dev = qdev_device_add_from_qdict(opt->opts, true, &error_fatal); > > + object_unref(OBJECT(dev)); > > loc_pop(&opt->loc); > > } > > rom_reset_order_override(); > > diff --git a/tests/qtest/device-plug-test.c b/tests/qtest/device-plug-test.c > > index 559d47727a..ad79bd4c14 100644 > > --- a/tests/qtest/device-plug-test.c > > +++ b/tests/qtest/device-plug-test.c > > @@ -77,6 +77,23 @@ static void test_pci_unplug_request(void) > > qtest_quit(qtest); > > } > > +static void test_pci_unplug_json_request(void) > > +{ > > + QTestState *qtest = qtest_initf( > > + "-device '{\"driver\": \"virtio-mouse-pci\", \"id\": \"dev0\"}'"); > > + > > + /* > > + * Request device removal. As the guest is not running, the request > > won't > > + * be processed. However during system reset, the removal will be > > + * handled, removing the device. > > + */ > > + device_del(qtest, "dev0"); > > + system_reset(qtest); > > You can use qpci_unplug_acpi_device_test() to process the request... but I > see this is done like that too in test_pci_unplug_request() > > > + wait_device_deleted_event(qtest, "dev0"); > > + > > + qtest_quit(qtest); > > +} > > + > > static void test_ccw_unplug(void) > > { > > QTestState *qtest = qtest_initf("-device virtio-balloon-ccw,id=dev0"); > > @@ -145,6 +162,8 @@ int main(int argc, char **argv) > > */ > > qtest_add_func("/device-plug/pci-unplug-request", > > test_pci_unplug_request); > > + qtest_add_func("/device-plug/pci-unplug-json-request", > > + test_pci_unplug_json_request); > > if (!strcmp(arch, "s390x")) { > > qtest_add_func("/device-plug/ccw-unplug", > > Reviewed-by: Laurent Vivier <lviv...@redhat.com> > Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
