target/s390x: report deprecated-props in cpu-model-expansion reply

Retain a list of deprecated features disjoint from any particular
CPU model. A query-cpu-model-expansion reply will now provide a list of
properties (i.e. features) that are flagged as deprecated. Example:

    {
      "return": {
        "model": {
          "name": "z14.2-base",
          "deprecated-props": [
            "bpb",
            "csske"
          ],
          "props": {
            "pfmfi": false,
            "exrl": true,
            ...a lot more props...
            "skey": false,
            "vxpdeh2": false
          }
        }
      }
    }

It is recommended that s390 guests operate with these features
explicitly disabled to ensure compatibility with future hardware.

Signed-off-by: Collin Walling <walling@linux.ibm.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-ID: <20240429191059.11806-2-walling@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

4 files changed, 29 insertions, 1 deletions

diff --git a/qapi/machine-target.json b/qapi/machine-target.json
index 29e695a..2942853 100644
--- a/qapi/machine-target.json
+++ b/qapi/machine-target.json
@@ -20,11 +20,16 @@
 #
 # @props: a dictionary of QOM properties to be applied
 #
+# @deprecated-props: a list of properties that are flagged as deprecated
+#     by the CPU vendor.  These props are a subset of the full model's
+#     definition list of properties. (since 9.1)
+#
 # Since: 2.8
 ##
 { 'struct': 'CpuModelInfo',
   'data': { 'name': 'str',
-            '*props': 'any' } }
+            '*props': 'any',
+            '*deprecated-props': ['str'] } }
 
 ##
 # @CpuModelExpansionType:
diff --git a/target/s390x/cpu_features.c b/target/s390x/cpu_features.c
index d28eb65..efafc97 100644
--- a/target/s390x/cpu_features.c
+++ b/target/s390x/cpu_features.c
@@ -212,6 +212,20 @@ void s390_feat_bitmap_to_ascii(const S390FeatBitmap features, void *opaque,
     };
 }
 
+void s390_get_deprecated_features(S390FeatBitmap features)
+{
+    static const int feats[] = {
+         /* CSSKE is deprecated on newer generations */
+         S390_FEAT_CONDITIONAL_SSKE,
+         S390_FEAT_BPB,
+    };
+    int i;
+
+    for (i = 0; i < ARRAY_SIZE(feats); i++) {
+        set_bit(feats[i], features);
+    }
+}
+
 #define FEAT_GROUP_INIT(_name, _group, _desc)        \
     {                                                \
         .name = _name,                               \
diff --git a/target/s390x/cpu_features.h b/target/s390x/cpu_features.h
index a9bd68a..661a8cd 100644
--- a/target/s390x/cpu_features.h
+++ b/target/s390x/cpu_features.h
@@ -69,6 +69,7 @@ void s390_add_from_feat_block(S390FeatBitmap features, S390FeatType type,
                           uint8_t *data);
 void s390_feat_bitmap_to_ascii(const S390FeatBitmap features, void *opaque,
                                void (*fn)(const char *name, void *opaque));
+void s390_get_deprecated_features(S390FeatBitmap features);
 
 /* Definition of a CPU feature group */
 typedef struct {
diff --git a/target/s390x/cpu_models_sysemu.c b/target/s390x/cpu_models_sysemu.c
index 15be729..977fbc6 100644
--- a/target/s390x/cpu_models_sysemu.c
+++ b/target/s390x/cpu_models_sysemu.c
@@ -206,6 +206,14 @@ static void cpu_info_from_model(CpuModelInfo *info, const S390CPUModel *model,
     } else {
         info->props = QOBJECT(qdict);
     }
+
+    /* features flagged as deprecated */
+    bitmap_zero(bitmap, S390_FEAT_MAX);
+    s390_get_deprecated_features(bitmap);
+
+    bitmap_and(bitmap, bitmap, model->def->full_feat, S390_FEAT_MAX);
+    s390_feat_bitmap_to_ascii(bitmap, &info->deprecated_props, list_add_feat);
+    info->has_deprecated_props = !!info->deprecated_props;
 }
 
 CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,