cpu-common.c: export cpu_get_free_index to be reused later

This helper provides an easy way to identify the next available free cpu
index which can be used for vcpu creation. Until now, this is being
called at a very later stage and there is a need to be able to call it
earlier (for now, with ppc64) hence the need to export.

Suggested-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

cpu-common.c

@@ -57,14 +57,12 @@ void cpu_list_unlock(void)
     qemu_mutex_unlock(&qemu_cpu_list_lock);
 }
 
-static bool cpu_index_auto_assigned;
 
-static int cpu_get_free_index(void)
+int cpu_get_free_index(void)
 {
     CPUState *some_cpu;
     int max_cpu_index = 0;
 
-    cpu_index_auto_assigned = true;
     CPU_FOREACH(some_cpu) {
         if (some_cpu->cpu_index >= max_cpu_index) {
             max_cpu_index = some_cpu->cpu_index + 1;
@@ -83,8 +81,11 @@ unsigned int cpu_list_generation_id_get(void)
 
 void cpu_list_add(CPUState *cpu)
 {
+    static bool cpu_index_auto_assigned;
+
     QEMU_LOCK_GUARD(&qemu_cpu_list_lock);
     if (cpu->cpu_index == UNASSIGNED_CPU_INDEX) {
+        cpu_index_auto_assigned = true;
         cpu->cpu_index = cpu_get_free_index();
         assert(cpu->cpu_index != UNASSIGNED_CPU_INDEX);
     } else {

include/exec/cpu-common.h

@@ -35,6 +35,8 @@ void cpu_list_lock(void);
 void cpu_list_unlock(void);
 unsigned int cpu_list_generation_id_get(void);
 
+int cpu_get_free_index(void);
+
 void tcg_iommu_init_notifier_list(CPUState *cpu);
 void tcg_iommu_free_notifier_list(CPUState *cpu);