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

Pierre Morel
2022-10-12T16:21:38Z

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>
---
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