perf intel-pt: Track guest context switches

Use guest context switch events to keep track of which guest thread is
running on a particular guest machine and VCPU.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: kvm@vger.kernel.org
Link: https://lore.kernel.org/r/20220711093218.10967-31-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/intel-pt.c

@@ -78,6 +78,7 @@ struct intel_pt {
 	bool use_thread_stack;
 	bool callstack;
 	bool cap_event_trace;
+	bool have_guest_sideband;
 	unsigned int br_stack_sz;
 	unsigned int br_stack_sz_plus;
 	int have_sched_switch;
@@ -3079,6 +3080,25 @@ static int intel_pt_context_switch_in(struct intel_pt *pt,
 	return machine__set_current_tid(pt->machine, cpu, pid, tid);
 }
 
+static int intel_pt_guest_context_switch(struct intel_pt *pt,
+					 union perf_event *event,
+					 struct perf_sample *sample)
+{
+	bool out = event->header.misc & PERF_RECORD_MISC_SWITCH_OUT;
+	struct machines *machines = &pt->session->machines;
+	struct machine *machine = machines__find(machines, sample->machine_pid);
+
+	pt->have_guest_sideband = true;
+
+	if (out)
+		return 0;
+
+	if (!machine)
+		return -EINVAL;
+
+	return machine__set_current_tid(machine, sample->vcpu, sample->pid, sample->tid);
+}
+
 static int intel_pt_context_switch(struct intel_pt *pt, union perf_event *event,
 				   struct perf_sample *sample)
 {
@@ -3086,6 +3106,9 @@ static int intel_pt_context_switch(struct intel_pt *pt, union perf_event *event,
 	pid_t pid, tid;
 	int cpu, ret;
 
+	if (perf_event__is_guest(event))
+		return intel_pt_guest_context_switch(pt, event, sample);
+
 	cpu = sample->cpu;
 
 	if (pt->have_sched_switch == 3) {