[PATCH] hw/core: Handle cpu_model_from_type() returning NULL value

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Per cpu_model_from_type() docstring (added in commit 445946f4dd):

  * Returns: CPU model name or NULL if the CPU class doesn't exist

We must check the return value in order to avoid surprises, i.e.:

 $ qemu-system-arm -machine virt -cpu cortex-a9
  qemu-system-arm: Invalid CPU model: cortex-a9
  The valid models are: cortex-a7, cortex-a15, (null), (null), (null), (null), (null), (null), (null), (null), (null), (null), (null), max

Add assertions when the call can not fail (because the CPU type
must be registered).

Fixes: 5422d2a8fa ("machine: Print CPU model name instead of CPU type")
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 cpu-target.c          | 1 +
 hw/core/machine.c     | 5 +++++
 target/ppc/cpu_init.c | 1 +
 3 files changed, 7 insertions(+)

diff --git a/cpu-target.c b/cpu-target.c
index 5eecd7ea2d..b0f6deb13b 100644
--- a/cpu-target.c
+++ b/cpu-target.c
@@ -291,6 +291,7 @@ static void cpu_list_entry(gpointer data, gpointer user_data)
     const char *typename = object_class_get_name(OBJECT_CLASS(data));
     g_autofree char *model = cpu_model_from_type(typename);
 
+    assert(model);
     if (cc->deprecation_note) {
         qemu_printf("  %s (deprecated)\n", model);
     } else {
diff --git a/hw/core/machine.c b/hw/core/machine.c
index fc239101f9..730ec10328 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -1422,16 +1422,21 @@ static bool is_cpu_type_supported(const MachineState *machine, Error **errp)
         /* The user specified CPU type isn't valid */
         if (!mc->valid_cpu_types[i]) {
             g_autofree char *requested = cpu_model_from_type(machine->cpu_type);
+            assert(requested);
             error_setg(errp, "Invalid CPU model: %s", requested);
             if (!mc->valid_cpu_types[1]) {
                 g_autofree char *model = cpu_model_from_type(
                                                  mc->valid_cpu_types[0]);
+                assert(model);
                 error_append_hint(errp, "The only valid type is: %s\n", model);
             } else {
                 error_append_hint(errp, "The valid models are: ");
                 for (i = 0; mc->valid_cpu_types[i]; i++) {
                     g_autofree char *model = cpu_model_from_type(
                                                  mc->valid_cpu_types[i]);
+                    if (!model) {
+                        continue;
+                    }
                     error_append_hint(errp, "%s%s",
                                       model,
                                       mc->valid_cpu_types[i + 1] ? ", " : "");
diff --git a/target/ppc/cpu_init.c b/target/ppc/cpu_init.c
index 344196a8ce..58f0c1e30e 100644
--- a/target/ppc/cpu_init.c
+++ b/target/ppc/cpu_init.c
@@ -7037,6 +7037,7 @@ static void ppc_cpu_list_entry(gpointer data, gpointer user_data)
     }
 
     name = cpu_model_from_type(typename);
+    assert(name);
     qemu_printf("PowerPC %-16s PVR %08x\n", name, pcc->pvr);
     for (i = 0; ppc_cpu_aliases[i].alias != NULL; i++) {
         PowerPCCPUAlias *alias = &ppc_cpu_aliases[i];
-- 
2.41.0