[PATCH-for-9.0] hw/core: Add machine_class_default_cpu_type()

[Philippe Mathieu-Daudé]

Add a helper to return a machine default CPU type.

If this machine is restricted to a single CPU type,
use it as default, obviously.

Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org>
---
 include/hw/boards.h | 6 ++++++
 hw/core/machine.c   | 8 ++++++++
 system/vl.c         | 2 +-
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/include/hw/boards.h b/include/hw/boards.h
index da85f86efb..160a10036e 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -24,6 +24,12 @@ OBJECT_DECLARE_TYPE(MachineState, MachineClass, MACHINE)
 
 extern MachineState *current_machine;
 
+/**
+ * machine_class_default_cpu_type: Return the machine default CPU type.
+ * @mc: Machine class
+ */
+const char *machine_class_default_cpu_type(MachineClass *mc);
+
 void machine_add_audiodev_property(MachineClass *mc);
 void machine_run_board_init(MachineState *machine, const char *mem_path, Error 
**errp);
 bool machine_usb(MachineState *machine);
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 0c17398141..baf25c3fc5 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -1387,6 +1387,14 @@ out:
     return r;
 }
 
+const char *machine_class_default_cpu_type(MachineClass *mc)
+{
+    if (mc->valid_cpu_types && !mc->valid_cpu_types[1]) {
+        /* Only a single CPU type allowed: use it as default. */
+        return mc->valid_cpu_types[0];
+    }
+    return mc->default_cpu_type;
+}
 
 void machine_run_board_init(MachineState *machine, const char *mem_path, Error 
**errp)
 {
diff --git a/system/vl.c b/system/vl.c
index 5af7ced2a1..1c28162b21 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -3730,7 +3730,7 @@ void qemu_init(int argc, char **argv)
     migration_object_init();
 
     /* parse features once if machine provides default cpu_type */
-    current_machine->cpu_type = machine_class->default_cpu_type;
+    current_machine->cpu_type = machine_class_default_cpu_type(machine_class);
     if (cpu_option) {
         current_machine->cpu_type = parse_cpu_option(cpu_option);
     }
-- 
2.41.0