[PATCH v4 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 b42493110d76..11676b81e6bf 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -4060,6 +4060,8 @@ 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..9ac92dbf680d 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