[PATCH v3 2/2] KVM: s390: add tracepoint in gmap notifier

[Nico Boehr <nrb@linux.ibm.com>]

The gmap notifier is called for changes in table entries with the
notifier bit set. To diagnose performance issues, it can be useful to
see what causes certain changes in the gmap.

Hence, add a tracepoint in the gmap notifier.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
---
 arch/s390/kvm/kvm-s390.c   |  2 ++
 arch/s390/kvm/trace-s390.h | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 9379471081fa..f643c9b9f2f3 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -3987,6 +3987,8 @@ static void kvm_gmap_notifier(struct gmap *gmap, unsigned long start,
 	unsigned long prefix;
 	unsigned long i;
 
+	trace_kvm_s390_gmap_notifier(start, end, gmap_is_shadow(gmap));
+
 	if (gmap_is_shadow(gmap))
 		return;
 	if (start >= 1UL << 31)
diff --git a/arch/s390/kvm/trace-s390.h b/arch/s390/kvm/trace-s390.h
index 6f0209d45164..5dabd0b64d6e 100644
--- a/arch/s390/kvm/trace-s390.h
+++ b/arch/s390/kvm/trace-s390.h
@@ -333,6 +333,29 @@ TRACE_EVENT(kvm_s390_airq_suppressed,
 		      __entry->id, __entry->isc)
 	);
 
+/*
+ * Trace point for gmap notifier calls.
+ */
+TRACE_EVENT(kvm_s390_gmap_notifier,
+		TP_PROTO(unsigned long start, unsigned long end, unsigned int shadow),
+		TP_ARGS(start, end, shadow),
+
+		TP_STRUCT__entry(
+			__field(unsigned long, start)
+			__field(unsigned long, end)
+			__field(unsigned int, shadow)
+			),
+
+		TP_fast_assign(
+			__entry->start = start;
+			__entry->end = end;
+			__entry->shadow = shadow;
+			),
+
+		TP_printk("gmap notified (start:0x%lx end:0x%lx shadow:%d)",
+			__entry->start, __entry->end, __entry->shadow)
+	);
+
 
 #endif /* _TRACE_KVMS390_H */
 
-- 
2.41.0