[PATCH v10 3/9] s390x/cpu_topology: resetting the Topology-Change-Report

Pierre Morel
2022-10-12T16:21:42Z

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>
Reviewed-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
---
target/s390x/cpu.h | 1 +
target/s390x/kvm/kvm_s390x.h | 1 +
hw/s390x/cpu-topology.c | 12 ++++++++++++
hw/s390x/s390-virtio-ccw.c | 1 +
target/s390x/cpu-sysemu.c | 7 +++++++
target/s390x/kvm/kvm.c | 23 +++++++++++++++++++++++
6 files changed, 45 insertions(+)

diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index d604aa9c78..9b35795ac8 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -825,6 +825,7 @@ 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_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 */
diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
index c73cebfe6f..9f202621d0 100644
--- a/hw/s390x/cpu-topology.c
+++ b/hw/s390x/cpu-topology.c
@@ -107,6 +107,17 @@ 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
@@ -120,6 +131,7 @@ 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 aa99a62e42..362378454a 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -113,6 +113,7 @@ 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/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;
+}
--
2.31.1