[PATCH 2/2] perf kvm stat live: Enable events copying

[Alexander Yarygin <yarygin@linux.vnet.ibm.com>]

Process of analyzing events caused by 2 functions: mmap_read() and
finished_round().
During mmap_read(), perf receives events from shared memory, queues
their pointers for further processing in finished_round() and notifies
the kernel that the events have been processed.
By the time when finished_round() is invoked, queued events can be
overwritten by the kernel, so the finished_round() occurs on potentially
corrupted memory.

Let's copy events when queueing.

Signed-off-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 tools/perf/builtin-kvm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index f5d3ae4..c5b6d1d 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -1369,6 +1369,7 @@ static int kvm_events_live(struct perf_kvm_stat *kvm,
 		goto out;
 	}
 	kvm->session->evlist = kvm->evlist;
+	kvm->session->copy_on_queue = true;
 	perf_session__set_id_hdr_size(kvm->session);
 	machine__synthesize_threads(&kvm->session->machines.host, &kvm->opts.target,
 				    kvm->evlist->threads, false);
-- 
1.9.1