diff --git a/qemu/include/qom/cpu.h b/qemu/include/qom/cpu.h
index dd95073f..75e0f35f 100644
--- a/qemu/include/qom/cpu.h
+++ b/qemu/include/qom/cpu.h
@@ -223,6 +223,11 @@ struct CPUAddressSpace {
 /**
  * CPUState:
  * @cpu_index: CPU index (informative).
+ * @cluster_index: Identifies which cluster this CPU is in.
+ *   For boards which don't define clusters or for "loose" CPUs not assigned
+ *   to a cluster this will be UNASSIGNED_CLUSTER_INDEX; otherwise it will
+ *   be the same as the cluster-id property of the CPU object's TYPE_CPU_CLUSTER
+ *   QOM parent.
  * @nr_cores: Number of cores within this CPU package.
  * @nr_threads: Number of threads within this CPU.
  * @host_tid: Host thread ID.
@@ -316,6 +321,7 @@ struct CPUState {
 
     /* TODO Move common fields from CPUArchState here. */
     int cpu_index;
+    int cluster_index;
     uint32_t halted;
     union {
         uint32_t u32;
diff --git a/qemu/qom/cpu.c b/qemu/qom/cpu.c
index 307b9254..a87a89c8 100644
--- a/qemu/qom/cpu.c
+++ b/qemu/qom/cpu.c
@@ -259,6 +259,7 @@ static void cpu_common_initfn(struct uc_struct *uc, Object *obj, void *opaque)
     CPUState *cpu = CPU(obj);
 
     cpu->cpu_index = -1;
+    cpu->cluster_index = -1;
     QTAILQ_INIT(&cpu->breakpoints);
     QTAILQ_INIT(&cpu->watchpoints);
 }