perf: 'perf kvm' tool for monitoring guest performance from host

Here is the patch of userspace perf tool.

Signed-off-by: Zhang Yanmin <yanmin_zhang@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index 04904b3..0f60a390 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -24,7 +24,7 @@
 	}
 
 	thread__find_addr_map(thread, session, cpumode, MAP__FUNCTION,
-			      event->ip.ip, &al);
+			      event->ip.pid, event->ip.ip, &al);
 
 	if (al.map != NULL)
 		al.map->dso->hit = 1;