[PATCH v13 6/7] s390x/cpu_topology: activating CPU topology

[Pierre Morel <pmorel@linux.ibm.com>]

The KVM capability, KVM_CAP_S390_CPU_TOPOLOGY is used to
activate the S390_FEAT_CONFIGURATION_TOPOLOGY feature and
the topology facility for the guest in the case the topology
is available in QEMU and in KVM.

The feature is disabled by default and fenced for SE
(secure execution).

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
 include/hw/s390x/cpu-topology.h | 10 +++++++++-
 hw/s390x/cpu-topology.c         |  5 ++---
 target/s390x/cpu_models.c       |  1 +
 target/s390x/kvm/kvm.c          | 12 ++++++++++++
 4 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/include/hw/s390x/cpu-topology.h b/include/hw/s390x/cpu-topology.h
index 6c3d2d080f..fe25a3bf6b 100644
--- a/include/hw/s390x/cpu-topology.h
+++ b/include/hw/s390x/cpu-topology.h
@@ -38,7 +38,15 @@ struct S390Topology {
 OBJECT_DECLARE_SIMPLE_TYPE(S390Topology, S390_CPU_TOPOLOGY)
 
 void s390_init_topology(MachineState *machine, Error **errp);
-bool s390_has_topology(void);
 S390Topology *s390_get_topology(void);
 
+#ifdef CONFIG_KVM
+bool s390_has_topology(void);
+#else
+static inline bool s390_has_topology(void)
+{
+    return false;
+}
+#endif
+
 #endif
diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
index a2a553e362..bf125bb4c0 100644
--- a/hw/s390x/cpu-topology.c
+++ b/hw/s390x/cpu-topology.c
@@ -75,12 +75,11 @@ void s390_handle_ptf(S390CPU *cpu, uint8_t r1, uintptr_t ra)
 /**
  * s390_has_topology
  *
- * Return false until the commit activating the topology is
- * commited.
+ * checks the S390_FEAT_CONFIGURATION_TOPOLOGY availability.
  */
 bool s390_has_topology(void)
 {
-    return false;
+    return s390_has_feat(S390_FEAT_CONFIGURATION_TOPOLOGY);
 }
 
 /**
diff --git a/target/s390x/cpu_models.c b/target/s390x/cpu_models.c
index c3a4f80633..3f05e05fd3 100644
--- a/target/s390x/cpu_models.c
+++ b/target/s390x/cpu_models.c
@@ -253,6 +253,7 @@ bool s390_has_feat(S390Feat feat)
         case S390_FEAT_SIE_CMMA:
         case S390_FEAT_SIE_PFMFI:
         case S390_FEAT_SIE_IBS:
+        case S390_FEAT_CONFIGURATION_TOPOLOGY:
             return false;
             break;
         default:
diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
index a79fdf1c79..abf1202c28 100644
--- a/target/s390x/kvm/kvm.c
+++ b/target/s390x/kvm/kvm.c
@@ -2471,6 +2471,18 @@ void kvm_s390_get_host_cpu_model(S390CPUModel *model, Error **errp)
         set_bit(S390_FEAT_UNPACK, model->features);
     }
 
+    /*
+     * If we have support for CPU Topology in KVM
+     * activate the CPU TOPOLOGY feature.
+     */
+    if (kvm_check_extension(kvm_state, KVM_CAP_S390_CPU_TOPOLOGY)) {
+        if (kvm_vm_enable_cap(kvm_state, KVM_CAP_S390_CPU_TOPOLOGY, 0) < 0) {
+            error_setg(errp, "KVM: Error enabling KVM_CAP_S390_CPU_TOPOLOGY");
+            return;
+        }
+        set_bit(S390_FEAT_CONFIGURATION_TOPOLOGY, 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);
-- 
2.31.1