From: Pierre Morel <pmorel@linux.ibm.com>

When the guest asks to change the polarization this change
is forwarded to the upper layer using QAPI.
The upper layer is supposed to take according decisions concerning
CPU provisioning.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Co-developed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Message-ID: <20231016183925.2384704-13-nsg@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 qapi/machine-target.json | 35 +++++++++++++++++++++++++++++++++++
 hw/s390x/cpu-topology.c  |  2 ++
 2 files changed, 37 insertions(+)

diff --git a/qapi/machine-target.json b/qapi/machine-target.json
index 7688f32ffa..ac93a5f82c 100644
--- a/qapi/machine-target.json
+++ b/qapi/machine-target.json
@@ -417,3 +417,38 @@
   'features': [ 'unstable' ],
   'if': { 'all': [ 'TARGET_S390X' , 'CONFIG_KVM' ] }
 }
+
+##
+# @CPU_POLARIZATION_CHANGE:
+#
+# Emitted when the guest asks to change the polarization.
+#
+# The guest can tell the host (via the PTF instruction) whether the
+# CPUs should be provisioned using horizontal or vertical polarization.
+#
+# On horizontal polarization the host is expected to provision all vCPUs
+# equally.
+#
+# On vertical polarization the host can provision each vCPU differently.
+# The guest will get information on the details of the provisioning
+# the next time it uses the STSI(15) instruction.
+#
+# @polarization: polarization specified by the guest
+#
+# Features:
+#
+# @unstable: This event is experimental.
+#
+# Since: 8.2
+#
+# Example:
+#
+# <- { "event": "CPU_POLARIZATION_CHANGE",
+#      "data": { "polarization": "horizontal" },
+#      "timestamp": { "seconds": 1401385907, "microseconds": 422329 } }
+##
+{ 'event': 'CPU_POLARIZATION_CHANGE',
+  'data': { 'polarization': 'CpuS390Polarization' },
+  'features': [ 'unstable' ],
+  'if': { 'all': [ 'TARGET_S390X', 'CONFIG_KVM' ] }
+}
diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
index f3771f5045..327bccea4f 100644
--- a/hw/s390x/cpu-topology.c
+++ b/hw/s390x/cpu-topology.c
@@ -24,6 +24,7 @@
 #include "hw/s390x/s390-virtio-ccw.h"
 #include "hw/s390x/cpu-topology.h"
 #include "qapi/qapi-commands-machine-target.h"
+#include "qapi/qapi-events-machine-target.h"
 
 /*
  * s390_topology is used to keep the topology information.
@@ -136,6 +137,7 @@ void s390_handle_ptf(S390CPU *cpu, uint8_t r1, uintptr_t ra)
         } else {
             s390_topology.polarization = polarization;
             s390_cpu_topology_set_changed(true);
+            qapi_event_send_cpu_polarization_change(polarization);
             setcc(cpu, 0);
         }
         break;
-- 
2.41.0