The 'stm32vldiscovery' 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-aarch64 -M stm32vldiscovery -cpu neoverse-n1

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-aarch64 -M stm32vldiscovery -cpu neoverse-n1
  qemu-system-aarch64: Invalid CPU type: neoverse-n1-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/stm32f100_soc.h | 4 ----
 hw/arm/stm32f100_soc.c         | 9 ++-------
 hw/arm/stm32vldiscovery.c      | 7 ++++++-
 3 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/include/hw/arm/stm32f100_soc.h b/include/hw/arm/stm32f100_soc.h
index 40cd415b28..a74d7b369c 100644
--- a/include/hw/arm/stm32f100_soc.h
+++ b/include/hw/arm/stm32f100_soc.h
@@ -43,12 +43,8 @@ OBJECT_DECLARE_SIMPLE_TYPE(STM32F100State, STM32F100_SOC)
 #define SRAM_SIZE (8 * 1024)
 
 struct STM32F100State {
-    /*< private >*/
     SysBusDevice parent_obj;
 
-    /*< public >*/
-    char *cpu_type;
-
     ARMv7MState armv7m;
 
     STM32F2XXUsartState usart[STM_NUM_USARTS];
diff --git a/hw/arm/stm32f100_soc.c b/hw/arm/stm32f100_soc.c
index f7b344ba9f..b90d440d7a 100644
--- a/hw/arm/stm32f100_soc.c
+++ b/hw/arm/stm32f100_soc.c
@@ -115,7 +115,7 @@ static void stm32f100_soc_realize(DeviceState *dev_soc, Error **errp)
     /* Init ARMv7m */
     armv7m = DEVICE(&s->armv7m);
     qdev_prop_set_uint32(armv7m, "num-irq", 61);
-    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);
@@ -180,17 +180,12 @@ static void stm32f100_soc_realize(DeviceState *dev_soc, Error **errp)
     create_unimplemented_device("CRC",       0x40023000, 0x400);
 }
 
-static Property stm32f100_soc_properties[] = {
-    DEFINE_PROP_STRING("cpu-type", STM32F100State, cpu_type),
-    DEFINE_PROP_END_OF_LIST(),
-};
-
 static void stm32f100_soc_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
 
     dc->realize = stm32f100_soc_realize;
-    device_class_set_props(dc, stm32f100_soc_properties);
+    /* No vmstate or reset required: device has no internal state */
 }
 
 static const TypeInfo stm32f100_soc_info = {
diff --git a/hw/arm/stm32vldiscovery.c b/hw/arm/stm32vldiscovery.c
index 67675e952f..6300dca722 100644
--- a/hw/arm/stm32vldiscovery.c
+++ b/hw/arm/stm32vldiscovery.c
@@ -47,7 +47,6 @@ static void stm32vldiscovery_init(MachineState *machine)
     clock_set_hz(sysclk, SYSCLK_FRQ);
 
     dev = qdev_new(TYPE_STM32F100_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);
 
@@ -58,8 +57,14 @@ static void stm32vldiscovery_init(MachineState *machine)
 
 static void stm32vldiscovery_machine_init(MachineClass *mc)
 {
+    static const char *machine_valid_cpu_types[] = {
+        ARM_CPU_TYPE_NAME("cortex-m3"),
+        NULL
+    };
+
     mc->desc = "ST STM32VLDISCOVERY (Cortex-M3)";
     mc->init = stm32vldiscovery_init;
+    mc->valid_cpu_types = machine_valid_cpu_types;
 }
 
 DEFINE_MACHINE("stm32vldiscovery", stm32vldiscovery_machine_init)
-- 
2.41.0

On 16/11/23 00:21, Philippe Mathieu-Daudé wrote:
> The 'stm32vldiscovery' 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-aarch64 -M stm32vldiscovery -cpu neoverse-n1
> 
> 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-aarch64 -M stm32vldiscovery -cpu neoverse-n1
>    qemu-system-aarch64: Invalid CPU type: neoverse-n1-arm-cpu
>    The valid types are: cortex-m3-arm-cpu

With [2] from cover applied, this becomes:

      $ qemu-system-aarch64 -M stm32vldiscovery -cpu neoverse-n1 -S
      qemu-system-aarch64: Invalid CPU type: neoverse-n1
      The valid types are: cortex-m3

> 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/stm32f100_soc.h | 4 ----
>   hw/arm/stm32f100_soc.c         | 9 ++-------
>   hw/arm/stm32vldiscovery.c      | 7 ++++++-
>   3 files changed, 8 insertions(+), 12 deletions(-)

[2] 
https://lore.kernel.org/qemu-devel/20231114235628.534334-1-gshan@redhat.com/