[Qemu-devel] [PATCH 10/10] s390x/cpumodel: do not claim csske for expanded models in qmp

[Christian Borntraeger]

While we have removed csske and bpb from the default model, the very
common case of "host-model" in libvirt (expanded to a base model
+ features) would still contain bpb and csske. This can prevent
migration to a future machine for a host-model machine. Let us fence
bpb and csske when we run on a generation 15. If necessary the
user can still use -cpu 8561,csske=on,bpb=on to force enable these
features.

Signed-off-by: Christian Borntraeger <address@hidden>
---
 target/s390x/cpu_models.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/target/s390x/cpu_models.c b/target/s390x/cpu_models.c
index e727519686..03bdca1fb8 100644
--- a/target/s390x/cpu_models.c
+++ b/target/s390x/cpu_models.c
@@ -629,6 +629,17 @@ CpuModelExpansionInfo 
*qmp_query_cpu_model_expansion(CpuModelExpansionType type,
         return NULL;
     }
 
+    /*
+     * Do not claim CSSKE and BPB if the host model expands to
+     * generation 15 or newer
+     */
+    if (s390_model.def->gen >= 15) {
+        clear_bit(S390_FEAT_CONDITIONAL_SSKE,
+                  (unsigned long *) &s390_model.features);
+        clear_bit(S390_FEAT_BPB,
+                  (unsigned long *) &s390_model.features);
+    }
+
     if (type == CPU_MODEL_EXPANSION_TYPE_STATIC) {
         delta_changes = true;
     } else if (type != CPU_MODEL_EXPANSION_TYPE_FULL) {
-- 
2.19.1