[PATCH v10 4/9] s390x/cpu_topology: CPU topology migration

[Pierre Morel <pmorel@xxxxxxxxxxxxx>]

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@xxxxxxxxxxxxx>
---
 include/hw/s390x/cpu-topology.h |  1 +
 target/s390x/cpu.h              |  1 +
 hw/s390x/cpu-topology.c         | 79 +++++++++++++++++++++++++++++++++
 target/s390x/cpu-sysemu.c       |  8 ++++
 4 files changed, 89 insertions(+)

diff --git a/include/hw/s390x/cpu-topology.h b/include/hw/s390x/cpu-topology.h
index 61c11db017..35a8a981ec 100644
--- a/include/hw/s390x/cpu-topology.h
+++ b/include/hw/s390x/cpu-topology.h
@@ -28,6 +28,7 @@ typedef struct S390TopoTLE {
 struct S390Topology {
     SysBusDevice parent_obj;
     int cpus;
+    bool topology_needed;
     S390TopoContainer *socket;
     S390TopoTLE *tle;
     MachineState *ms;
diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index 9b35795ac8..8495bfafde 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -826,6 +826,7 @@ 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 9f202621d0..349f0ad89d 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"
 
 S390Topology *s390_get_topology(void)
 {
@@ -118,6 +119,83 @@ 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
@@ -132,6 +210,7 @@ static void topology_class_init(ObjectClass *oc, void *data)
     dc->realize = s390_topology_realize;
     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 707c0b658c..78cb11c0f8 100644
--- a/target/s390x/cpu-sysemu.c
+++ b/target/s390x/cpu-sysemu.c
@@ -313,3 +313,11 @@ void s390_cpu_topology_reset(void)
         kvm_s390_topology_set_mtcr(0);
     }
 }
+
+int s390_cpu_topology_mtcr_set(void)
+{
+    if (kvm_enabled()) {
+        return kvm_s390_topology_set_mtcr(1);
+    }
+    return -ENOENT;
+}
-- 
2.31.1