Akihiko Odaki <akihiko.od...@daynix.com> writes: > On 2023/12/11 15:51, Markus Armbruster wrote: >> Akihiko Odaki <akihiko.od...@daynix.com> writes: >> >>> The HotplugHandler of the machine will be used when the parent bus does >>> not exist, but the machine may not have one. Report an error in such a >>> case instead of aborting. >>> >>> Fixes: 7716b8ca74 ("qdev: HotplugHandler: Add support for unplugging >>> BUS-less devices") >>> Signed-off-by: Akihiko Odaki <akihiko.od...@daynix.com> >> >> Do you have a reproducer for the crash? >> >>> --- >>> Changes in v2: >>> - Fixed indention. >>> - Link to v1: >>> https://lore.kernel.org/r/20231202-bus-v1-1-f7540e3a8...@daynix.com >>> --- >>> system/qdev-monitor.c | 13 ++++++++++--- >>> 1 file changed, 10 insertions(+), 3 deletions(-) >>> >>> diff --git a/system/qdev-monitor.c b/system/qdev-monitor.c >>> index a13db763e5..5fe5d49c20 100644 >>> --- a/system/qdev-monitor.c >>> +++ b/system/qdev-monitor.c >>> @@ -927,9 +927,16 @@ void qdev_unplug(DeviceState *dev, Error **errp) >> void qdev_unplug(DeviceState *dev, Error **errp) >> { >> DeviceClass *dc = DEVICE_GET_CLASS(dev); >> HotplugHandler *hotplug_ctrl; >> HotplugHandlerClass *hdc; >> Error *local_err = NULL; >> if (qdev_unplug_blocked(dev, errp)) { >> return; >> } >> if (dev->parent_bus && !qbus_is_hotpluggable(dev->parent_bus)) { >> error_setg(errp, QERR_BUS_NO_HOTPLUG, dev->parent_bus->name); >> return; >> } >> if (!dc->hotpluggable) { >> error_setg(errp, QERR_DEVICE_NO_HOTPLUG, >> object_get_typename(OBJECT(dev))); >> return; >> } >> if (!migration_is_idle() && !dev->allow_unplug_during_migration) { >> error_setg(errp, "device_del not allowed while migrating"); >> return; >> } >> >>> qdev_hot_removed = true; >>> hotplug_ctrl = qdev_get_hotplug_handler(dev); >>> - /* hotpluggable device MUST have HotplugHandler, if it doesn't >>> - * then something is very wrong with it */ >>> - g_assert(hotplug_ctrl); >>> + if (!hotplug_ctrl) { >>> + /* >>> + * hotpluggable bus MUST have HotplugHandler, if it doesn't >>> + * then something is very wrong with it >>> + */ >>> + assert(!dev->parent_bus); >>> + >>> + error_setg(errp, "The machine does not support hotplugging for a >>> device without parent bus"); >>> + return; >>> + } >> >> Extended version of my question above: what are the devices where >> qdev_get_hotplug_handler(dev) returns null here? > > Start a VM: qemu-system-aarch64 -M virt -nographic > Run the following on its HMP: device_del /machine/unattached/device[0] > > It tries to unplug cortex-a15-arm-cpu and crashes.
This device has no parent bus (dev->parent_bus is null), but is marked hot-pluggable (dc->hotpluggable is true). Question for somebody familiar with the hot-plug machinery: is this sane?