From: Christian Borntraeger <borntraeger@de.ibm.com>

The unpack facility is an indication that diagnose 308 subcodes 8-10
are available to the guest. That means, that the guest can put itself
into protected mode.

Once it is in protected mode, the hardware stops any attempt of VM
introspection by the hypervisor.

Some features are currently not supported in protected mode:
     * Passthrough devices
     * Migration
     * Huge page backings

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
 target/s390x/gen-features.c | 1 +
 target/s390x/kvm.c          | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/target/s390x/gen-features.c b/target/s390x/gen-features.c
index 6278845b12..8ddeebc544 100644
--- a/target/s390x/gen-features.c
+++ b/target/s390x/gen-features.c
@@ -562,6 +562,7 @@ static uint16_t full_GEN15_GA1[] = {
     S390_FEAT_GROUP_MSA_EXT_9,
     S390_FEAT_GROUP_MSA_EXT_9_PCKMO,
     S390_FEAT_ETOKEN,
+    S390_FEAT_UNPACK,
 };
 
 /* Default features (in order of release)
diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
index 5c7757ac28..ade0752f0c 100644
--- a/target/s390x/kvm.c
+++ b/target/s390x/kvm.c
@@ -2400,6 +2400,11 @@ void kvm_s390_get_host_cpu_model(S390CPUModel *model, Error **errp)
         clear_bit(S390_FEAT_BPB, model->features);
     }
 
+    /* we do have the IPL enhancements */
+    if (cap_protected) {
+        set_bit(S390_FEAT_UNPACK, model->features);
+    }
+
     /* We emulate a zPCI bus and AEN, therefore we don't need HW support */
     set_bit(S390_FEAT_ZPCI, model->features);
     set_bit(S390_FEAT_ADAPTER_EVENT_NOTIFICATION, model->features);
-- 
2.20.1