hw/machine: added machine_usb wrapper

Following QOM convention, object properties should
not be accessed directly.
Signed-off-by: NMarcel Apfelbaum <marcel@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

hw/core/machine.c

@@ -398,6 +398,11 @@ static void machine_finalize(Object *obj)
     g_free(ms->firmware);
 }
 
+bool machine_usb(MachineState *machine)
+{
+    return machine->usb;
+}
+
 static const TypeInfo machine_info = {
     .name = TYPE_MACHINE,
     .parent = TYPE_OBJECT,

include/hw/boards.h

@@ -65,6 +65,8 @@ int qemu_register_machine(QEMUMachine *m);
 MachineClass *find_default_machine(void);
 extern MachineState *current_machine;
 
+bool machine_usb(MachineState *machine);
+
 /**
  * MachineClass:
  * @qemu_machine: #QEMUMachine