exec: Ensure the only one cpu_index allocation method is used

Make sure that cpu_index auto allocation isn't used in
combination with manual cpu_index assignment. And
dissallow out of order cpu removal if auto allocation
is in use.

Target that wishes to support out of order unplug should
switch to manual cpu_index assignment. Following patch
could be used as an example:
 (pc: init CPUState->cpu_index with index in possible_cpus[]))

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/exec.c b/exec.c
index 8ffde75983..80398b038f 100644
--- a/exec.c
+++ b/exec.c
@@ -598,11 +598,14 @@ AddressSpace *cpu_get_address_space(CPUState *cpu, int asidx)
 }
 #endif
 
+static bool cpu_index_auto_assigned;
+
 static int cpu_get_free_index(void)
 {
     CPUState *some_cpu;
     int cpu_index = 0;
 
+    cpu_index_auto_assigned = true;
     CPU_FOREACH(some_cpu) {
         cpu_index++;
     }
@@ -620,6 +623,8 @@ void cpu_exec_exit(CPUState *cpu)
         return;
     }
 
+    assert(!(cpu_index_auto_assigned && cpu != QTAILQ_LAST(&cpus, CPUTailQ)));
+
     QTAILQ_REMOVE(&cpus, cpu, node);
     cpu->node.tqe_prev = NULL;
     cpu->cpu_index = UNASSIGNED_CPU_INDEX;
@@ -663,6 +668,8 @@ void cpu_exec_init(CPUState *cpu, Error **errp)
     if (cpu->cpu_index == UNASSIGNED_CPU_INDEX) {
         cpu->cpu_index = cpu_get_free_index();
         assert(cpu->cpu_index != UNASSIGNED_CPU_INDEX);
+    } else {
+        assert(!cpu_index_auto_assigned);
     }
     QTAILQ_INSERT_TAIL(&cpus, cpu, node);
     cpu_list_unlock();