[PATCH v16 05/11] s390x/cpu topology: resetting the Topology-Change-Report

Pierre Morel
2023-02-22T14:21:30Z

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: Thomas Huth <thuth@redhat.com>
---
include/hw/s390x/cpu-topology.h | 1 +
target/s390x/cpu.h | 1 +
target/s390x/kvm/kvm_s390x.h | 1 +
hw/s390x/cpu-topology.c | 11 +++++++++++
hw/s390x/s390-virtio-ccw.c | 3 +++
target/s390x/cpu-sysemu.c | 13 +++++++++++++
target/s390x/kvm/kvm.c | 17 +++++++++++++++++
7 files changed, 47 insertions(+)

diff --git a/include/hw/s390x/cpu-topology.h b/include/hw/s390x/cpu-topology.h
index 8dc42d2942..b9688f0213 100644
--- a/include/hw/s390x/cpu-topology.h
+++ b/include/hw/s390x/cpu-topology.h
@@ -58,6 +58,7 @@ static inline void s390_topology_setup_cpu(MachineState *ms,

extern S390Topology s390_topology;
int s390_socket_nb(S390CPU *cpu);
+void s390_topology_reset(void);

static inline int s390_std_socket(int n, CpuTopology *smp)
{
diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index c899f4e04b..bfe4bd2c19 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, uint64_t addr, uint8_t ar);
+void s390_cpu_topology_set_changed(bool changed);

/* 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 85ad9ef0d7..08642e0e04 100644
--- a/hw/s390x/cpu-topology.c
+++ b/hw/s390x/cpu-topology.c
@@ -87,6 +87,17 @@ 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()
+ * to reset the kernel Modified Topology Change Record.
+ */
+void s390_topology_reset(void)
+{
+ s390_cpu_topology_set_changed(false);
+}
+
/**
* 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 42b6438204..a52e45e591 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..9d41acfe1a 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_set_changed(bool changed)
+{
+ int ret;
+
+ if (kvm_enabled()) {
+ ret = kvm_s390_topology_set_mtcr(changed);
+ 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