[PATCH v9 06/10] s390x/cpu_topology: resetting the Topology-Change-Report

[Pierre Morel <pmorel@linux.ibm.com>]

During a subsystem reset the Topology-Change-Report is cleared
by the machine.
Let's ask KVM to clear the Modified Topology Change Report (MTCR)
 bit of the SCA in the case of a subsystem reset.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
 hw/s390x/cpu-topology.c      | 12 ++++++++++++
 hw/s390x/s390-virtio-ccw.c   |  1 +
 target/s390x/cpu-sysemu.c    |  7 +++++++
 target/s390x/cpu.h           |  1 +
 target/s390x/kvm/kvm.c       | 23 +++++++++++++++++++++++
 target/s390x/kvm/kvm_s390x.h |  1 +
 6 files changed, 45 insertions(+)

diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
index bb9ae63483..6098d6ea1f 100644
--- a/hw/s390x/cpu-topology.c
+++ b/hw/s390x/cpu-topology.c
@@ -121,6 +121,17 @@ static void s390_topology_realize(DeviceState *dev, Error **errp)
     qemu_mutex_init(&topo->topo_mutex);
 }
 
+/**
+ * s390_topology_reset:
+ * @dev: the device
+ *
+ * Calls the sysemu topology reset
+ */
+static void s390_topology_reset(DeviceState *dev)
+{
+    s390_cpu_topology_reset();
+}
+
 /**
  * topology_class_init:
  * @oc: Object class
@@ -134,6 +145,7 @@ 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;
 }
 
 static const TypeInfo cpu_topology_info = {
diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index 3f28e28d47..1fa98740de 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -104,6 +104,7 @@ static const char *const reset_dev_types[] = {
     "s390-flic",
     "diag288",
     TYPE_S390_PCI_HOST_BRIDGE,
+    TYPE_S390_CPU_TOPOLOGY,
 };
 
 static void subsystem_reset(void)
diff --git a/target/s390x/cpu-sysemu.c b/target/s390x/cpu-sysemu.c
index 948e4bd3e0..707c0b658c 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_reset(void)
+{
+    if (kvm_enabled()) {
+        kvm_s390_topology_set_mtcr(0);
+    }
+}
diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index c61fe9b563..cff5cc0415 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_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 f96630440b..9c994d27d5 100644
--- a/target/s390x/kvm/kvm.c
+++ b/target/s390x/kvm/kvm.c
@@ -2585,3 +2585,26 @@ int kvm_s390_get_zpci_op(void)
 {
     return cap_zpci_op;
 }
+
+int kvm_s390_topology_set_mtcr(uint64_t attr)
+{
+    struct kvm_device_attr attribute = {
+        .group = KVM_S390_VM_CPU_TOPOLOGY,
+        .attr  = attr,
+    };
+    int ret;
+
+    if (!s390_has_feat(S390_FEAT_CONFIGURATION_TOPOLOGY)) {
+        return -EFAULT;
+    }
+    if (!kvm_vm_check_attr(kvm_state, KVM_S390_VM_CPU_TOPOLOGY, attr)) {
+        return -ENOENT;
+    }
+
+    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));
+    }
+    return ret;
+}
diff --git a/target/s390x/kvm/kvm_s390x.h b/target/s390x/kvm/kvm_s390x.h
index aaae8570de..a13c8fb9a3 100644
--- a/target/s390x/kvm/kvm_s390x.h
+++ b/target/s390x/kvm/kvm_s390x.h
@@ -46,5 +46,6 @@ void kvm_s390_crypto_reset(void);
 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);
+int kvm_s390_topology_set_mtcr(uint64_t attr);
 
 #endif /* KVM_S390X_H */
-- 
2.31.1