sysbus: Make devices spawnable via -device

Now that we can properly map sysbus devices that haven't been connected to
something forcefully by C code, we can allow the -device command line option
to spawn them.

For machines that don't implement dynamic sysbus assignment in their board
files we add a new bool "has_dynamic_sysbus" to the machine class.
When that property is false (default), we bail out when we see dynamically
spawned sysbus devices, like we did before.

Signed-off-by: Alexander Graf <agraf@suse.de>

hw/core/machine.c

@@ -12,6 +12,9 @@
 
 #include "hw/boards.h"
 #include "qapi/visitor.h"
+#include "hw/sysbus.h"
+#include "sysemu/sysemu.h"
+#include "qemu/error-report.h"
 
 static char *machine_get_accel(Object *obj, Error **errp)
 {
@@ -257,8 +260,35 @@ static void machine_set_iommu(Object *obj, bool value, Error **errp)
     ms->iommu = value;
 }
 
+static int error_on_sysbus_device(SysBusDevice *sbdev, void *opaque)
+{
+    error_report("Option '-device %s' cannot be handled by this machine",
+                 object_class_get_name(object_get_class(OBJECT(sbdev))));
+    exit(1);
+}
+
+static void machine_init_notify(Notifier *notifier, void *data)
+{
+    Object *machine = qdev_get_machine();
+    ObjectClass *oc = object_get_class(machine);
+    MachineClass *mc = MACHINE_CLASS(oc);
+
+    if (mc->has_dynamic_sysbus) {
+        /* Our machine can handle dynamic sysbus devices, we're all good */
+        return;
+    }
+
+    /*
+     * Loop through all dynamically created devices and check whether there
+     * are sysbus devices among them. If there are, error out.
+     */
+    foreach_dynamic_sysbus_device(error_on_sysbus_device, NULL);
+}
+
 static void machine_initfn(Object *obj)
 {
+    MachineState *ms = MACHINE(obj);
+
     object_property_add_str(obj, "accel",
                             machine_get_accel, machine_set_accel, NULL);
     object_property_add_bool(obj, "kernel-irqchip",
@@ -303,6 +333,10 @@ static void machine_initfn(Object *obj)
     object_property_add_bool(obj, "iommu",
                              machine_get_iommu,
                              machine_set_iommu, NULL);
+
+    /* Register notifier when init is done for sysbus sanity checks */
+    ms->sysbus_notifier.notify = machine_init_notify;
+    qemu_add_machine_init_done_notifier(&ms->sysbus_notifier);
 }
 
 static void machine_finalize(Object *obj)

hw/core/sysbus.c

@@ -283,13 +283,6 @@ static void sysbus_device_class_init(ObjectClass *klass, void *data)
     DeviceClass *k = DEVICE_CLASS(klass);
     k->init = sysbus_device_init;
     k->bus_type = TYPE_SYSTEM_BUS;
-    /*
-     * device_add plugs devices into suitable bus.  For "real" buses,
-     * that actually connects the device.  For sysbus, the connections
-     * need to be made separately, and device_add can't do that.  The
-     * device would be left unconnected, and could not possibly work.
-     */
-    k->cannot_instantiate_with_device_add_yet = true;
 }
 
 static const TypeInfo sysbus_device_type_info = {

include/hw/boards.h

@@ -36,7 +36,8 @@ struct QEMUMachine {
         use_sclp:1,
         no_floppy:1,
         no_cdrom:1,
-        no_sdcard:1;
+        no_sdcard:1,
+        has_dynamic_sysbus:1;
     int is_default;
     const char *default_machine_opts;
     const char *default_boot_order;
@@ -97,7 +98,8 @@ struct MachineClass {
         use_sclp:1,
         no_floppy:1,
         no_cdrom:1,
-        no_sdcard:1;
+        no_sdcard:1,
+        has_dynamic_sysbus:1;
     int is_default;
     const char *default_machine_opts;
     const char *default_boot_order;
@@ -115,6 +117,8 @@ struct MachineClass {
 struct MachineState {
     /*< private >*/
     Object parent_obj;
+    Notifier sysbus_notifier;
+
     /*< public >*/
 
     char *accel;

vl.c

@@ -1441,6 +1441,7 @@ static void machine_class_init(ObjectClass *oc, void *data)
     mc->no_floppy = qm->no_floppy;
     mc->no_cdrom = qm->no_cdrom;
     mc->no_sdcard = qm->no_sdcard;
+    mc->has_dynamic_sysbus = qm->has_dynamic_sysbus;
     mc->is_default = qm->is_default;
     mc->default_machine_opts = qm->default_machine_opts;
     mc->default_boot_order = qm->default_boot_order;