[PATCH v8 10/12] s390x/cpu_topology: resetting the Topology-Change-Report

[Pierre Morel <pmorel@xxxxxxxxxxxxx>]

During a subsystem reset the Topology-Change-Report is cleared.
Let's ask KVM to clear the MTCR in the case of a subsystem reset.

Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
---
 hw/s390x/cpu-topology.c      |  6 ++++++
 hw/s390x/s390-virtio-ccw.c   |  1 +
 target/s390x/cpu-sysemu.c    |  7 +++++++
 target/s390x/cpu.h           |  1 +
 target/s390x/kvm/kvm.c       | 30 ++++++++++++++++++++++++++++++
 target/s390x/kvm/kvm_s390x.h |  2 ++
 6 files changed, 47 insertions(+)

diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
index 2dbb42ee2b..ba12cafaf7 100644
--- a/hw/s390x/cpu-topology.c
+++ b/hw/s390x/cpu-topology.c
@@ -667,6 +667,11 @@ static void s390_node_device_realize(DeviceState *dev, Error **errp)
     qbus_set_hotplug_handler(bus, OBJECT(dev));
 }
 
+static void s390_topology_reset(DeviceState *dev)
+{
+    s390_cpu_topology_mtr_reset();
+}
+
 static void node_class_init(ObjectClass *oc, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(oc);
@@ -676,6 +681,7 @@ static void node_class_init(ObjectClass *oc, void *data)
     set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
     dc->realize = s390_node_device_realize;
     dc->desc = "topology node";
+    dc->reset = s390_topology_reset;
 }
 
 static const TypeInfo node_info = {
diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index 5c0dbff6fd..0b30633ed5 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -122,6 +122,7 @@ static const char *const reset_dev_types[] = {
     "s390-flic",
     "diag288",
     TYPE_S390_PCI_HOST_BRIDGE,
+    TYPE_S390_TOPOLOGY_NODE,
 };
 
 static void subsystem_reset(void)
diff --git a/target/s390x/cpu-sysemu.c b/target/s390x/cpu-sysemu.c
index 948e4bd3e0..11d0d87301 100644
--- a/target/s390x/cpu-sysemu.c
+++ b/target/s390x/cpu-sysemu.c
@@ -306,3 +306,10 @@ void s390_do_cpu_set_diag318(CPUState *cs, run_on_cpu_data arg)
         kvm_s390_set_diag318(cs, arg.host_ulong);
     }
 }
+
+void s390_cpu_topology_mtr_reset(void)
+{
+    if (kvm_enabled()) {
+        kvm_s390_cpu_topology_reset();
+    }
+}
diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index 9d48087b71..793e72c81a 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -826,6 +826,7 @@ void s390_enable_css_support(S390CPU *cpu);
 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_mtr_reset(void);
 #ifndef CONFIG_USER_ONLY
 unsigned int s390_cpu_set_state(uint8_t cpu_state, S390CPU *cpu);
 #else
diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
index c664c45e8a..277f8d37cf 100644
--- a/target/s390x/kvm/kvm.c
+++ b/target/s390x/kvm/kvm.c
@@ -2592,3 +2592,33 @@ bool kvm_arch_cpu_check_are_resettable(void)
 {
     return true;
 }
+
+static void kvm_s390_set_mtr(uint64_t attr)
+{
+    struct kvm_device_attr attribute = {
+        .group = KVM_S390_VM_CPU_TOPOLOGY,
+        .attr  = attr,
+    };
+    int ret = kvm_vm_ioctl(kvm_state, KVM_SET_DEVICE_ATTR, &attribute);
+
+    if (ret) {
+        error_report("Failed to set cpu topology attribute %lu: %s",
+                     attr, strerror(-ret));
+    }
+}
+
+static void kvm_s390_reset_mtr(void)
+{
+    uint64_t attr = KVM_S390_VM_CPU_TOPO_MTR_CLEAR;
+
+    if (kvm_vm_check_attr(kvm_state, KVM_S390_VM_CPU_TOPOLOGY, attr)) {
+            kvm_s390_set_mtr(attr);
+    }
+}
+
+void kvm_s390_cpu_topology_reset(void)
+{
+    if (s390_has_feat(S390_FEAT_CONFIGURATION_TOPOLOGY)) {
+        kvm_s390_reset_mtr();
+    }
+}
diff --git a/target/s390x/kvm/kvm_s390x.h b/target/s390x/kvm/kvm_s390x.h
index 05a5e1e6f4..d717c05827 100644
--- a/target/s390x/kvm/kvm_s390x.h
+++ b/target/s390x/kvm/kvm_s390x.h
@@ -46,4 +46,6 @@ void kvm_s390_restart_interrupt(S390CPU *cpu);
 void kvm_s390_stop_interrupt(S390CPU *cpu);
 void kvm_s390_set_diag318(CPUState *cs, uint64_t diag318_info);
 
+void kvm_s390_cpu_topology_reset(void);
+
 #endif /* KVM_S390X_H */
-- 
2.31.1