[Qemu-devel] [PATCH] hw/core/qdev: Do not allow hot-plugging without hotplug controller

[Thomas Huth <thuth@redhat.com>]

qdev_unplug() bails out with an assertion if the user tries to device_del
a hot-plugged device that does not have a hotplug controller. Unfortunately,
our devices are all marked with hotpluggable = true by default (see the
device_class_init() function in qdev.c), so it currently can happen that
the user runs into this situation and QEMU gets terminated unexpectedly:

$ qemu-system-aarch64 -M virt -nographic -nodefaults -monitor stdio -S
QEMU 2.10.50 monitor - type 'help' for more information
(qemu) device_add aux-to-i2c-bridge,id=x
(qemu) device_del x
**
ERROR:qdev-monitor.c:872:qdev_unplug: assertion failed: (hotplug_ctrl)
Aborted (core dumped)

Hotplugging devices without a hotplug controller does not make much sense,
so we should disallow this during the device_add process already!

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 hw/core/qdev.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 606ab53..d9ccce6 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -908,6 +908,11 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
             if (local_err != NULL) {
                 goto fail;
             }
+        } else if (dev->hotplugged) {
+            /* Hot-plugged device without hotplug controller? No way! */
+            error_setg(&local_err, QERR_DEVICE_NO_HOTPLUG,
+                       object_get_typename(obj));
+            goto fail;
         }
 
         if (dc->realize) {
-- 
1.8.3.1