s390x/kvm: Enable KSS facility for nested virtualization

If the host supports keyless subset (KSS) then first level
guest (G2) should enable KSS facility as well.
Signed-off-by: NFarhan Ali <alifm@linux.vnet.ibm.com>
Reviewed-by: NEric Farman <farman@linux.vnet.ibm.com>
Acked-by: NCornelia Huck <cohuck@redhat.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

target/s390x/kvm.c

@@ -2508,6 +2508,7 @@ static int kvm_to_feat[][2] = {
     { KVM_S390_VM_CPU_FEAT_CMMA, S390_FEAT_SIE_CMMA },
     { KVM_S390_VM_CPU_FEAT_PFMFI, S390_FEAT_SIE_PFMFI},
     { KVM_S390_VM_CPU_FEAT_SIGPIF, S390_FEAT_SIE_SIGPIF},
+    { KVM_S390_VM_CPU_FEAT_KSS, S390_FEAT_SIE_KSS},
 };
 
 static int query_cpu_feat(S390FeatBitmap features)