spapr_cpu_core: instantiate CPUs separately

The current code assumes that only the CPU core object holds a
reference on each individual CPU object, and happily frees their
allocated memory when the core is unrealized. This is dangerous
as some other code can legitimely keep a pointer to a CPU if it
calls object_ref(), but it would end up with a dangling pointer.

Let's allocate all CPUs with object_new() and let QOM free them
when their reference count reaches zero. This greatly simplify the
code as we don't have to fiddle with the instance size anymore.

Signed-off-by: Greg Kurz <groug@kaod.org>
Acked-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

include/hw/ppc/spapr_cpu_core.h

@@ -28,7 +28,7 @@ typedef struct sPAPRCPUCore {
     CPUCore parent_obj;
 
     /*< public >*/
-    void *threads;
+    PowerPCCPU **threads;
     int node_id;
 } sPAPRCPUCore;