[PATCH v2 2/3] target/s390x: add support for "disable-deprecated-feats" expansion option

[Collin Walling]

Retain a list of deprecated features disjoint from any particular
CPU model. When a query-cpu-model-expansion is provided with the
"disable-deprecated-feats" option set, the resulting properties list
will include all deprecated features paired with false. Example:

        { ... "bpb": false, "csske": false, ...}

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

Signed-off-by: Collin Walling <walling@linux.ibm.com>
---
 target/s390x/cpu_features.c      | 14 ++++++++++++++
 target/s390x/cpu_features.h      |  1 +
 target/s390x/cpu_models_sysemu.c | 20 ++++++++++++--------
 3 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/target/s390x/cpu_features.c b/target/s390x/cpu_features.c
index d28eb65845..efafc9711c 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 a9bd68a2e1..661a8cd6db 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 ef9fa80efd..b002819188 100644
--- a/target/s390x/cpu_models_sysemu.c
+++ b/target/s390x/cpu_models_sysemu.c
@@ -171,7 +171,8 @@ static void qdict_add_enabled_feat(const char *name, void 
*opaque)
 
 /* convert S390CPUDef into a static CpuModelInfo */
 static void cpu_info_from_model(CpuModelInfo *info, const S390CPUModel *model,
-                                bool delta_changes)
+                                bool delta_changes,
+                                bool disable_deprecated_feats)
 {
     QDict *qdict = qdict_new();
     S390FeatBitmap bitmap;
@@ -201,6 +202,13 @@ static void cpu_info_from_model(CpuModelInfo *info, const 
S390CPUModel *model,
         s390_feat_bitmap_to_ascii(bitmap, qdict, qdict_add_disabled_feat);
     }
 
+    /* features flagged as deprecated */
+    if (disable_deprecated_feats) {
+        bitmap_zero(bitmap, S390_FEAT_MAX);
+        s390_get_deprecated_features(bitmap);
+        s390_feat_bitmap_to_ascii(bitmap, qdict, qdict_add_disabled_feat);
+    }
+
     if (!qdict_size(qdict)) {
         qobject_unref(qdict);
     } else {
@@ -219,11 +227,6 @@ CpuModelExpansionInfo 
*qmp_query_cpu_model_expansion(CpuModelExpansionType type,
     S390CPUModel s390_model;
     bool delta_changes = false;
 
-    if (has_disable_deprecated_feats) {
-        error_setg(&err, "Unsupported option 'disable-deprecated-feats'");
-        return NULL;
-    }
-
     /* convert it to our internal representation */
     cpu_model_from_info(&s390_model, model, "model", &err);
     if (err) {
@@ -241,7 +244,8 @@ CpuModelExpansionInfo 
*qmp_query_cpu_model_expansion(CpuModelExpansionType type,
     /* convert it back to a static representation */
     expansion_info = g_new0(CpuModelExpansionInfo, 1);
     expansion_info->model = g_malloc0(sizeof(*expansion_info->model));
-    cpu_info_from_model(expansion_info->model, &s390_model, delta_changes);
+    cpu_info_from_model(expansion_info->model, &s390_model,
+                        delta_changes, disable_deprecated_feats);
     return expansion_info;
 }
 
@@ -390,7 +394,7 @@ CpuModelBaselineInfo 
*qmp_query_cpu_model_baseline(CpuModelInfo *infoa,
 
     baseline_info = g_new0(CpuModelBaselineInfo, 1);
     baseline_info->model = g_malloc0(sizeof(*baseline_info->model));
-    cpu_info_from_model(baseline_info->model, &model, true);
+    cpu_info_from_model(baseline_info->model, &model, true, false);
     return baseline_info;
 }
 
-- 
2.43.0