[PATCH v1 3/3] perf arm64: Support virtual CPU ID for kvm-stat

[Leo Yan <leo.yan@linaro.org>]

Since the two trace events kvm_entry_v2/kvm_exit_v2 are added, we can
use the field "vcpu_id" in the events to get to know the virtual CPU ID.
To keep backward compatibility, we still need to rely on the trace
events kvm_entry/kvm_exit for old kernels.

This patch adds Arm64's functions setup_kvm_events_tp() and
arm64__setup_kvm_tp(), by detecting the nodes under sysfs folder, it can
dynamically register trace events kvm_entry_v2/kvm_exit_v2 when the
kernel has provided them, otherwise, it rolls back to use events
kvm_entry/kvm_exit for backward compatibility.

Let cpu_isa_init() to invoke arm64__setup_kvm_tp(), this can allow the
command "perf kvm stat report" also to dynamically setup trace events.

Before:

  # perf kvm stat report --vcpu 27

  Analyze events for all VMs, VCPU 27:

               VM-EXIT    Samples  Samples%     Time%    Min Time    Max Time         Avg time

  Total Samples:0, Total events handled time:0.00us.

After:

  # perf kvm stat report --vcpu 27

  Analyze events for all VMs, VCPU 27:

               VM-EXIT    Samples  Samples%     Time%    Min Time    Max Time         Avg time

                 SYS64        808    98.54%    91.24%      0.00us    303.76us      3.46us ( +-  13.54% )
                   WFx         10     1.22%     7.79%      0.00us     69.48us     23.91us ( +-  25.91% )
                   IRQ          2     0.24%     0.97%      0.00us     22.64us     14.82us ( +-  52.77% )

  Total Samples:820, Total events handled time:3068.28us.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
 tools/perf/arch/arm64/util/kvm-stat.c | 54 ++++++++++++++++++++++++---
 1 file changed, 49 insertions(+), 5 deletions(-)

diff --git a/tools/perf/arch/arm64/util/kvm-stat.c b/tools/perf/arch/arm64/util/kvm-stat.c
index 73d18e0ed6f6..1ba54ce3d7d8 100644
--- a/tools/perf/arch/arm64/util/kvm-stat.c
+++ b/tools/perf/arch/arm64/util/kvm-stat.c
@@ -3,6 +3,7 @@
 #include <memory.h>
 #include "../../../util/evsel.h"
 #include "../../../util/kvm-stat.h"
+#include "../../../util/tracepoint.h"
 #include "arm64_exception_types.h"
 #include "debug.h"
 
@@ -10,18 +11,28 @@ define_exit_reasons_table(arm64_exit_reasons, kvm_arm_exception_type);
 define_exit_reasons_table(arm64_trap_exit_reasons, kvm_arm_exception_class);
 
 const char *kvm_trap_exit_reason = "esr_ec";
-const char *vcpu_id_str = "id";
+const char *vcpu_id_str = "vcpu_id";
 const int decode_str_len = 20;
 const char *kvm_exit_reason = "ret";
-const char *kvm_entry_trace = "kvm:kvm_entry";
-const char *kvm_exit_trace = "kvm:kvm_exit";
+const char *kvm_entry_trace;
+const char *kvm_exit_trace;
 
-const char *kvm_events_tp[] = {
+#define NR_TPS	2
+
+static const char *kvm_events_tp_v1[NR_TPS + 1] = {
 	"kvm:kvm_entry",
 	"kvm:kvm_exit",
 	NULL,
 };
 
+static const char *kvm_events_tp_v2[NR_TPS + 1] = {
+	"kvm:kvm_entry_v2",
+	"kvm:kvm_exit_v2",
+	NULL,
+};
+
+const char *kvm_events_tp[NR_TPS + 1];
+
 static void event_get_key(struct evsel *evsel,
 			  struct perf_sample *sample,
 			  struct event_key *key)
@@ -78,8 +89,41 @@ const char * const kvm_skip_events[] = {
 	NULL,
 };
 
-int cpu_isa_init(struct perf_kvm_stat *kvm, const char *cpuid __maybe_unused)
+static int arm64__setup_kvm_tp(struct perf_kvm_stat *kvm)
 {
+	const char **kvm_events, **events_ptr;
+	int i, nr_tp = 0;
+
+	if (is_valid_tracepoint("kvm:kvm_entry_v2")) {
+		kvm_events = kvm_events_tp_v2;
+		kvm_entry_trace = "kvm:kvm_entry_v2";
+		kvm_exit_trace = "kvm:kvm_exit_v2";
+	} else {
+		kvm_events = kvm_events_tp_v1;
+		kvm_entry_trace = "kvm:kvm_entry";
+		kvm_exit_trace = "kvm:kvm_exit";
+	}
+
+	for (events_ptr = kvm_events; *events_ptr; events_ptr++) {
+		if (!is_valid_tracepoint(*events_ptr))
+			return -1;
+		nr_tp++;
+	}
+
+	for (i = 0; i < nr_tp; i++)
+		kvm_events_tp[i] = kvm_events[i];
+	kvm_events_tp[i] = NULL;
+
 	kvm->exit_reasons_isa = "arm64";
 	return 0;
 }
+
+int setup_kvm_events_tp(struct perf_kvm_stat *kvm)
+{
+	return arm64__setup_kvm_tp(kvm);
+}
+
+int cpu_isa_init(struct perf_kvm_stat *kvm, const char *cpuid __maybe_unused)
+{
+	return arm64__setup_kvm_tp(kvm);
+}
-- 
2.34.1