perf kvm: Introduce histograms data structures

This is a preparation to support histograms in perf kvm tool.  As first
step, this patch defines histograms data structures and initialize them.

Committer notes:

Those are only used by functions enclosed in:

  #if efined(HAVE_KVM_STAT_SUPPORT) && defined(HAVE_LIBTRACEEVENT)

So do this for these new functions and struct as well.
Reviewed-by: James Clark <james.clark@arm.com>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20230315145112.186603-2-leo.yan@linaro.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-kvm.c

@@ -85,6 +85,20 @@ static struct kvm_event_key keys[] = {
 	DEF_SORT_NAME_KEY(time, mean),
 	{ NULL, NULL }
 };
+
+struct kvm_hists {
+	struct hists		hists;
+	struct perf_hpp_list	list;
+};
+
+static struct kvm_hists kvm_hists;
+
+static int kvm_hists__init(void)
+{
+	__hists__init(&kvm_hists.hists, &kvm_hists.list);
+	perf_hpp_list__init(&kvm_hists.list);
+	return 0;
+}
 #endif // defined(HAVE_KVM_STAT_SUPPORT) && defined(HAVE_LIBTRACEEVENT)
 
 static const char *get_filename_for_perf_kvm(void)
@@ -959,6 +973,8 @@ static int kvm_events_live_report(struct perf_kvm_stat *kvm)
 	set_term_quiet_input(&save);
 	init_kvm_event_record(kvm);
 
+	kvm_hists__init();
+
 	signal(SIGINT, sig_handler);
 	signal(SIGTERM, sig_handler);
 
@@ -1154,6 +1170,8 @@ static int kvm_events_report_vcpu(struct perf_kvm_stat *kvm)
 	init_kvm_event_record(kvm);
 	setup_pager();
 
+	kvm_hists__init();
+
 	ret = read_events(kvm);
 	if (ret)
 		goto exit;

tools/perf/util/kvm-stat.h

@@ -5,6 +5,7 @@
 #ifdef HAVE_KVM_STAT_SUPPORT
 
 #include "tool.h"
+#include "sort.h"
 #include "stat.h"
 #include "record.h"