target: Improve error reporting for CpuModelInfo member @props

query-cpu-model-comparison, query-cpu-model-baseline, and
query-cpu-model-expansion take CpuModelInfo arguments.  Errors in
@props members of these arguments are reported for 'props', without
further context.  For instance, s390x rejects

    {"execute": "query-cpu-model-comparison", "arguments": {"modela": {"name": "z13", "props": {}}, "modelb": {"name": "z14", "props": []}}}

with

    {"error": {"class": "GenericError", "desc": "Invalid parameter type for 'props', expected: object"}}

This is unusual; the common QAPI unmarshaling machinery would complain
about 'modelb.props'.  Our hand-written code to visit the @props
member neglects to provide the context.

Tweak it so it provides it.  The command above now fails with

    {"error": {"class": "GenericError", "desc": "Invalid parameter type for 'modelb.props', expected: dict"}}

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240305145919.2186971-4-armbru@redhat.com>
Acked-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/target/i386/cpu-sysemu.c b/target/i386/cpu-sysemu.c
index df91f97827..3f9093d285 100644
--- a/target/i386/cpu-sysemu.c
+++ b/target/i386/cpu-sysemu.c
@@ -130,14 +130,15 @@ static void x86_cpu_to_dict_full(X86CPU *cpu, QDict *props)
     }
 }
 
-static void object_apply_props(Object *obj, QObject *props, Error **errp)
+static void object_apply_props(Object *obj, QObject *props,
+                               const char *props_arg_name, Error **errp)
 {
     Visitor *visitor;
     QDict *qdict;
     const QDictEntry *prop;
 
     visitor = qobject_input_visitor_new(props);
-    if (!visit_start_struct(visitor, "props", NULL, 0, errp)) {
+    if (!visit_start_struct(visitor, props_arg_name, NULL, 0, errp)) {
         visit_free(visitor);
         return;
     }
@@ -158,7 +159,7 @@ out:
 
 /* Create X86CPU object according to model+props specification */
 static X86CPU *x86_cpu_from_model(const char *model, QObject *props,
-                                  Error **errp)
+                                  const char *props_arg_name, Error **errp)
 {
     X86CPU *xc = NULL;
     X86CPUClass *xcc;
@@ -172,7 +173,7 @@ static X86CPU *x86_cpu_from_model(const char *model, QObject *props,
 
     xc = X86_CPU(object_new_with_class(OBJECT_CLASS(xcc)));
     if (props) {
-        object_apply_props(OBJECT(xc), props, &err);
+        object_apply_props(OBJECT(xc), props, props_arg_name, &err);
         if (err) {
             goto out;
         }
@@ -203,7 +204,7 @@ qmp_query_cpu_model_expansion(CpuModelExpansionType type,
     QDict *props = NULL;
     const char *base_name;
 
-    xc = x86_cpu_from_model(model->name, model->props, &err);
+    xc = x86_cpu_from_model(model->name, model->props, "model.props", &err);
     if (err) {
         goto out;
     }