The 'netduino2' machine ignores the CPU type requested by the
command line. This might confuse users, since the following will
create a machine with a Cortex-M3 CPU:

  $ qemu-system-arm -M netduino2 -cpu cortex-a9

Set the MachineClass::valid_cpu_types field (introduced in commit
c9cf636d48 "machine: Add a valid_cpu_types property").
Remove the now unused MachineClass::default_cpu_type field.

We now get:

  $ qemu-system-arm -M netduino2 -cpu cortex-a9
  qemu-system-arm: Invalid CPU type: cortex-a9-arm-cpu
  The valid types are: cortex-m3-arm-cpu

Since the SoC family can only use Cortex-M3 CPUs, hard-code the
CPU type name at the SoC level, removing the QOM property
entirely.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/hw/arm/stm32f205_soc.h | 4 ----
 hw/arm/netduino2.c             | 7 ++++++-
 hw/arm/stm32f205_soc.c         | 9 ++-------
 3 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/include/hw/arm/stm32f205_soc.h b/include/hw/arm/stm32f205_soc.h
index 5a4f776264..4f4c8bbebc 100644
--- a/include/hw/arm/stm32f205_soc.h
+++ b/include/hw/arm/stm32f205_soc.h
@@ -49,11 +49,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(STM32F205State, STM32F205_SOC)
 #define SRAM_SIZE (128 * 1024)
 
 struct STM32F205State {
-    /*< private >*/
     SysBusDevice parent_obj;
-    /*< public >*/
-
-    char *cpu_type;
 
     ARMv7MState armv7m;
 
diff --git a/hw/arm/netduino2.c b/hw/arm/netduino2.c
index 83753d53a3..94b6b379d6 100644
--- a/hw/arm/netduino2.c
+++ b/hw/arm/netduino2.c
@@ -44,7 +44,6 @@ static void netduino2_init(MachineState *machine)
     clock_set_hz(sysclk, SYSCLK_FRQ);
 
     dev = qdev_new(TYPE_STM32F205_SOC);
-    qdev_prop_set_string(dev, "cpu-type", ARM_CPU_TYPE_NAME("cortex-m3"));
     qdev_connect_clock_in(dev, "sysclk", sysclk);
     sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
 
@@ -54,8 +53,14 @@ static void netduino2_init(MachineState *machine)
 
 static void netduino2_machine_init(MachineClass *mc)
 {
+    static const char *machine_valid_cpu_types[] = {
+        ARM_CPU_TYPE_NAME("cortex-m3"),
+        NULL
+    };
+
     mc->desc = "Netduino 2 Machine (Cortex-M3)";
     mc->init = netduino2_init;
+    mc->valid_cpu_types = machine_valid_cpu_types;
     mc->ignore_memory_transaction_failures = true;
 }
 
diff --git a/hw/arm/stm32f205_soc.c b/hw/arm/stm32f205_soc.c
index c6b75a381d..1a548646f6 100644
--- a/hw/arm/stm32f205_soc.c
+++ b/hw/arm/stm32f205_soc.c
@@ -127,7 +127,7 @@ static void stm32f205_soc_realize(DeviceState *dev_soc, Error **errp)
 
     armv7m = DEVICE(&s->armv7m);
     qdev_prop_set_uint32(armv7m, "num-irq", 96);
-    qdev_prop_set_string(armv7m, "cpu-type", s->cpu_type);
+    qdev_prop_set_string(armv7m, "cpu-type", ARM_CPU_TYPE_NAME("cortex-m3"));
     qdev_prop_set_bit(armv7m, "enable-bitband", true);
     qdev_connect_clock_in(armv7m, "cpuclk", s->sysclk);
     qdev_connect_clock_in(armv7m, "refclk", s->refclk);
@@ -201,17 +201,12 @@ static void stm32f205_soc_realize(DeviceState *dev_soc, Error **errp)
     }
 }
 
-static Property stm32f205_soc_properties[] = {
-    DEFINE_PROP_STRING("cpu-type", STM32F205State, cpu_type),
-    DEFINE_PROP_END_OF_LIST(),
-};
-
 static void stm32f205_soc_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
 
     dc->realize = stm32f205_soc_realize;
-    device_class_set_props(dc, stm32f205_soc_properties);
+    /* No vmstate or reset required: device has no internal state */
 }
 
 static const TypeInfo stm32f205_soc_info = {
-- 
2.41.0