[PATCH v15 05/11] s390x/cpu topology: resetting the Topology-Change-Report

[Pierre Morel <pmorel@xxxxxxxxxxxxx>]

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@xxxxxxxxxxxxx>
---
 include/hw/s390x/cpu-topology.h |  1 +
 target/s390x/cpu.h              |  1 +
 target/s390x/kvm/kvm_s390x.h    |  1 +
 hw/s390x/cpu-topology.c         | 12 ++++++++++++
 hw/s390x/s390-virtio-ccw.c      |  3 +++
 target/s390x/cpu-sysemu.c       | 13 +++++++++++++
 target/s390x/kvm/kvm.c          | 17 +++++++++++++++++
 7 files changed, 48 insertions(+)

diff --git a/include/hw/s390x/cpu-topology.h b/include/hw/s390x/cpu-topology.h
index 1ae7e7c5e3..60e0b9fbfa 100644
--- a/include/hw/s390x/cpu-topology.h
+++ b/include/hw/s390x/cpu-topology.h
@@ -66,5 +66,6 @@ static inline void s390_topology_set_cpu(MachineState *ms,
 
 extern S390Topology s390_topology;
 int s390_socket_nb(S390CPU *cpu);
+void s390_topology_reset(void);
 
 #endif
diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index e1f6925856..848314d2a9 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -641,6 +641,7 @@ typedef struct SysIBTl_cpu {
 QEMU_BUILD_BUG_ON(sizeof(SysIBTl_cpu) != 16);
 
 void insert_stsi_15_1_x(S390CPU *cpu, int sel2, __u64 addr, uint8_t ar);
+void s390_cpu_topology_reset(void);
 
 /* MMU defines */
 #define ASCE_ORIGIN           (~0xfffULL) /* segment table origin             */
diff --git a/target/s390x/kvm/kvm_s390x.h b/target/s390x/kvm/kvm_s390x.h
index f9785564d0..649dae5948 100644
--- a/target/s390x/kvm/kvm_s390x.h
+++ b/target/s390x/kvm/kvm_s390x.h
@@ -47,5 +47,6 @@ 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 */
diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
index a80a1ebf22..cf63f3dd01 100644
--- a/hw/s390x/cpu-topology.c
+++ b/hw/s390x/cpu-topology.c
@@ -85,6 +85,18 @@ static void s390_topology_init(MachineState *ms)
     QTAILQ_INSERT_HEAD(&s390_topology.list, entry, next);
 }
 
+/**
+ * s390_topology_reset:
+ *
+ * Generic reset for CPU topology, calls s390_topology_reset()
+ * s390_topology_reset() to reset the kernel Modified Topology
+ * change record.
+ */
+void s390_topology_reset(void)
+{
+    s390_cpu_topology_reset();
+}
+
 /**
  * s390_topology_cpu_default:
  * @cpu: pointer to a S390CPU
diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index 9bc51a83f4..30fdfe41fa 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -122,6 +122,9 @@ static void subsystem_reset(void)
             device_cold_reset(dev);
         }
     }
+    if (s390_has_topology()) {
+        s390_topology_reset();
+    }
 }
 
 static int virtio_ccw_hcall_notify(const uint64_t *args)
diff --git a/target/s390x/cpu-sysemu.c b/target/s390x/cpu-sysemu.c
index 948e4bd3e0..e27864c5f5 100644
--- a/target/s390x/cpu-sysemu.c
+++ b/target/s390x/cpu-sysemu.c
@@ -306,3 +306,16 @@ 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)
+{
+    int ret;
+
+    if (kvm_enabled()) {
+        ret = kvm_s390_topology_set_mtcr(0);
+        if (ret) {
+            error_report("Failed to set Modified Topology Change Report: %s",
+                         strerror(-ret));
+        }
+    }
+}
diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
index 5ea358cbb0..bc953151ce 100644
--- a/target/s390x/kvm/kvm.c
+++ b/target/s390x/kvm/kvm.c
@@ -2592,6 +2592,23 @@ 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,
+    };
+
+    if (!s390_has_feat(S390_FEAT_CONFIGURATION_TOPOLOGY)) {
+        return 0;
+    }
+    if (!kvm_vm_check_attr(kvm_state, KVM_S390_VM_CPU_TOPOLOGY, attr)) {
+        return -ENOTSUP;
+    }
+
+    return kvm_vm_ioctl(kvm_state, KVM_SET_DEVICE_ATTR, &attribute);
+}
+
 void kvm_arch_accel_class_init(ObjectClass *oc)
 {
 }
-- 
2.31.1