perf intel-pt: Adjust sample flags for VM-Exit

Use the change of NR to detect whether an asynchronous branch is a VM-Exit.

Note VM-Entry is determined from the vmlaunch or vmresume instruction,
in which case, sample flags will show "VMentry" even if the VM-Entry fails.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/r/20210218095801.19576-10-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/intel-pt.c

@@ -1201,13 +1201,16 @@ static void intel_pt_sample_flags(struct intel_pt_queue *ptq)
 	if (ptq->state->flags & INTEL_PT_ABORT_TX) {
 		ptq->flags = PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_TX_ABORT;
 	} else if (ptq->state->flags & INTEL_PT_ASYNC) {
-		if (ptq->state->to_ip)
+		if (!ptq->state->to_ip)
+			ptq->flags = PERF_IP_FLAG_BRANCH |
+				     PERF_IP_FLAG_TRACE_END;
+		else if (ptq->state->from_nr && !ptq->state->to_nr)
+			ptq->flags = PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_CALL |
+				     PERF_IP_FLAG_VMEXIT;
+		else
 			ptq->flags = PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_CALL |
 				     PERF_IP_FLAG_ASYNC |
 				     PERF_IP_FLAG_INTERRUPT;
-		else
-			ptq->flags = PERF_IP_FLAG_BRANCH |
-				     PERF_IP_FLAG_TRACE_END;
 		ptq->insn_len = 0;
 	} else {
 		if (ptq->state->from_ip)