[PATCH v11 06/11] s390x/cpu_topology: CPU topology migration

[Pierre Morel]

The migration can only take place if both source and destination
of the migration both use or both do not use the CPU topology
facility.

We indicate a change in topology during migration postload for the
case the topology changed between source and destination.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
 target/s390x/cpu.h        |  1 +
 hw/s390x/cpu-topology.c   | 79 +++++++++++++++++++++++++++++++++++++++
 target/s390x/cpu-sysemu.c |  8 ++++
 3 files changed, 88 insertions(+)

diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index 70de251b07..53127c249c 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -857,6 +857,7 @@ void s390_do_cpu_set_diag318(CPUState *cs, run_on_cpu_data 
arg);
 int s390_assign_subch_ioeventfd(EventNotifier *notifier, uint32_t sch_id,
                                 int vq, bool assign);
 void s390_cpu_topology_reset(void);
+int s390_cpu_topology_mtcr_set(void);
 #ifndef CONFIG_USER_ONLY
 unsigned int s390_cpu_set_state(uint8_t cpu_state, S390CPU *cpu);
 #else
diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
index 21d2785b37..df4470d2b4 100644
--- a/hw/s390x/cpu-topology.c
+++ b/hw/s390x/cpu-topology.c
@@ -19,6 +19,7 @@
 #include "target/s390x/cpu.h"
 #include "hw/s390x/s390-virtio-ccw.h"
 #include "hw/s390x/cpu-topology.h"
+#include "migration/vmstate.h"
 
 /*
  * s390_topology_new_cpu:
@@ -105,6 +106,83 @@ static void s390_topology_reset(DeviceState *dev)
     s390_cpu_topology_reset();
 }
 
+/**
+ * cpu_topology_postload
+ * @opaque: a pointer to the S390Topology
+ * @version_id: version identifier
+ *
+ * We check that the topology is used or is not used
+ * on both side identically.
+ *
+ * If the topology is in use we set the Modified Topology Change Report
+ * on the destination host.
+ */
+static int cpu_topology_postload(void *opaque, int version_id)
+{
+    S390Topology *topo = opaque;
+    int ret;
+
+    if (topo->topology_needed != s390_has_topology()) {
+        if (topo->topology_needed) {
+            error_report("Topology facility is needed in destination");
+        } else {
+            error_report("Topology facility can not be used in destination");
+        }
+        return -EINVAL;
+    }
+
+    /* We do not support CPU Topology, all is good */
+    if (!s390_has_topology()) {
+        return 0;
+    }
+
+    /* We support CPU Topology, set the MTCR unconditionally */
+    ret = s390_cpu_topology_mtcr_set();
+    if (ret) {
+        error_report("Failed to set MTCR: %s", strerror(-ret));
+    }
+    return ret;
+}
+
+/**
+ * cpu_topology_presave:
+ * @opaque: The pointer to the S390Topology
+ *
+ * Save the usage of the CPU Topology in the VM State.
+ */
+static int cpu_topology_presave(void *opaque)
+{
+    S390Topology *topo = opaque;
+
+    topo->topology_needed = s390_has_topology();
+    return 0;
+}
+
+/**
+ * cpu_topology_needed:
+ * @opaque: The pointer to the S390Topology
+ *
+ * We always need to know if source and destination use the topology.
+ */
+static bool cpu_topology_needed(void *opaque)
+{
+    return true;
+}
+
+
+const VMStateDescription vmstate_cpu_topology = {
+    .name = "cpu_topology",
+    .version_id = 1,
+    .post_load = cpu_topology_postload,
+    .pre_save = cpu_topology_presave,
+    .minimum_version_id = 1,
+    .needed = cpu_topology_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_BOOL(topology_needed, S390Topology),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 /**
  * topology_class_init:
  * @oc: Object class
@@ -120,6 +198,7 @@ static void topology_class_init(ObjectClass *oc, void *data)
     device_class_set_props(dc, s390_topology_properties);
     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
     dc->reset = s390_topology_reset;
+    dc->vmsd = &vmstate_cpu_topology;
 }
 
 static const TypeInfo cpu_topology_info = {
diff --git a/target/s390x/cpu-sysemu.c b/target/s390x/cpu-sysemu.c
index e27864c5f5..a8e3e6219d 100644
--- a/target/s390x/cpu-sysemu.c
+++ b/target/s390x/cpu-sysemu.c
@@ -319,3 +319,11 @@ void s390_cpu_topology_reset(void)
         }
     }
 }
+
+int s390_cpu_topology_mtcr_set(void)
+{
+    if (kvm_enabled()) {
+        return kvm_s390_topology_set_mtcr(1);
+    }
+    return -ENOENT;
+}
-- 
2.31.1