[PATCH v1 3/3] KVM: s390: add tracepoint in gmap notifier

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

The gmap notifier is called whenever something in the gmap structures
changes. 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>
---
 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 b012645a5a7c..f66953bdabe4 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -3981,6 +3981,8 @@ 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 */
 
-- 
2.39.1