cpus: Cache CPUClass early in instance_init() handler

Cache CPUClass as early as possible, when the instance
is initialized.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20250123234415.59850-5-philmd@linaro.org>

cpu-target.c

@@ -134,9 +134,6 @@ const VMStateDescription vmstate_cpu_common = {
 
 bool cpu_exec_realizefn(CPUState *cpu, Error **errp)
 {
-    /* cache the cpu class for the hotpath */
-    cpu->cc = CPU_GET_CLASS(cpu);
-
     if (!accel_cpu_common_realize(cpu, errp)) {
         return false;
     }

hw/core/cpu-common.c

@@ -238,6 +238,9 @@ static void cpu_common_initfn(Object *obj)
 {
     CPUState *cpu = CPU(obj);
 
+    /* cache the cpu class for the hotpath */
+    cpu->cc = CPU_GET_CLASS(cpu);
+
     gdb_init_cpu(cpu);
     cpu->cpu_index = UNASSIGNED_CPU_INDEX;
     cpu->cluster_index = UNASSIGNED_CLUSTER_INDEX;