[PATCH v2] target/s390x: filter deprecated properties based on model expansion type

[Collin Walling <walling@linux.ibm.com>]

As s390 CPU models progress and deprecated properties are dropped
outright, it will be cumbersome for management apps to query the host
for a comprehensive list of deprecated properties that will need to be
disabled on older models. To remedy this, the query-cpu-model-expansion
output now behaves by filtering deprecated properties based on the
expansion type instead of filtering based off of the model's full set
of features:

When reporting a static CPU model, only show deprecated properties that
are a subset of the model's enabled features.

When reporting a full CPU model, show the entire list of deprecated
properties regardless if they are supported on the model.

Suggested-by: Jiri Denemark <jdenemar@redhat.com>
Signed-off-by: Collin Walling <walling@linux.ibm.com>
---

Changelog:

    v2
    - Changed commit message
    - Added documentation reflecting this change
    - Made code changes that more accurately filter the deprecated
        properties based on expansion type.  This change makes it
        so that the deprecated-properties reported for a static model
        expansion are a subset of the model's properties instead of
        the model's full-definition properties.

        For example:

        Previously, the z900 static model would report 'bpb' in the
        list of deprecated-properties.  However, this prop is *not*
        a part of the model's feature set, leading to some inaccuracy
        (albeit harmless).

        Now, this feature will not show during a static expansion.
        It will, however, show up in a full expansion (along with
        the rest of the list: 'csske', 'te', 'cte').

@David, I've elected to respectully forgo adding your ack-by on this
iteration since I have changed the code (and therefore the behavior)
between this version and the previous in case you do not agree with
these adjustments.

---
 qapi/machine-target.json         |  8 ++++++--
 target/s390x/cpu_models_sysemu.c | 16 +++++++++-------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/qapi/machine-target.json b/qapi/machine-target.json
index a8d9ec87f5..d151504f25 100644
--- a/qapi/machine-target.json
+++ b/qapi/machine-target.json
@@ -21,8 +21,12 @@
 # @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)
+#     by the CPU vendor.  (since 9.1).
+#
+# .. note:: Since 9.1, the list of deprecated props were always a subset
+#    of the model's full-definition list of properites. Now, this list is
+#    populated with the model's enabled property set when delta changes
+#    are applied. All deprecated properties are reported otherwise.
 #
 # Since: 2.8
 ##
diff --git a/target/s390x/cpu_models_sysemu.c b/target/s390x/cpu_models_sysemu.c
index 977fbc6522..e28ecf7ab9 100644
--- a/target/s390x/cpu_models_sysemu.c
+++ b/target/s390x/cpu_models_sysemu.c
@@ -174,11 +174,15 @@ static void cpu_info_from_model(CpuModelInfo *info, const S390CPUModel *model,
                                 bool delta_changes)
 {
     QDict *qdict = qdict_new();
-    S390FeatBitmap bitmap;
+    S390FeatBitmap bitmap, deprecated;
 
     /* always fallback to the static base model */
     info->name = g_strdup_printf("%s-base", model->def->name);
 
+    /* features flagged as deprecated */
+    bitmap_zero(deprecated, S390_FEAT_MAX);
+    s390_get_deprecated_features(deprecated);
+
     if (delta_changes) {
         /* features deleted from the base feature set */
         bitmap_andnot(bitmap, model->def->base_feat, model->features,
@@ -193,6 +197,9 @@ static void cpu_info_from_model(CpuModelInfo *info, const S390CPUModel *model,
         if (!bitmap_empty(bitmap, S390_FEAT_MAX)) {
             s390_feat_bitmap_to_ascii(bitmap, qdict, qdict_add_enabled_feat);
         }
+
+        /* deprecated features that are a subset of the model's features */
+        bitmap_and(deprecated, deprecated, model->features, S390_FEAT_MAX);
     } else {
         /* expand all features */
         s390_feat_bitmap_to_ascii(model->features, qdict,
@@ -207,12 +214,7 @@ static void cpu_info_from_model(CpuModelInfo *info, const S390CPUModel *model,
         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);
+    s390_feat_bitmap_to_ascii(deprecated, &info->deprecated_props, list_add_feat);
     info->has_deprecated_props = !!info->deprecated_props;
 }
 
-- 
2.45.1