KVM: s390: enable IBS for single running VCPUs

This patch enables the IBS facility when a single VCPU is running.
The facility is dynamically turned on/off as soon as other VCPUs
enter/leave the stopped state.

When this facility is operating, some instructions can be executed
faster for single-cpu guests.

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/arch/s390/kvm/trace-s390.h b/arch/s390/kvm/trace-s390.h
index 34d4f8af3a1d..647e9d6a4818 100644
--- a/arch/s390/kvm/trace-s390.h
+++ b/arch/s390/kvm/trace-s390.h
@@ -244,6 +244,28 @@ TRACE_EVENT(kvm_s390_enable_css,
                       __entry->kvm)
         );
 
+/*
+ * Trace point for enabling and disabling interlocking-and-broadcasting
+ * suppression.
+ */
+TRACE_EVENT(kvm_s390_enable_disable_ibs,
+            TP_PROTO(unsigned int id, int state),
+            TP_ARGS(id, state),
+
+            TP_STRUCT__entry(
+                    __field(unsigned int, id)
+                    __field(int, state)
+                    ),
+
+            TP_fast_assign(
+                    __entry->id = id;
+                    __entry->state = state;
+                    ),
+
+            TP_printk("%s ibs on cpu %d",
+                      __entry->state ? "enabling" : "disabling", __entry->id)
+        );
+
 
 #endif /* _TRACE_KVMS390_H */