perf kvm/powerpc: Add support for HCALL reasons

Powerpc provides hcall events that also provides insights into guest
behaviour. Enhance perf kvm stat to record and analyze hcall events.

 - To trace hcall events :
  perf kvm stat record

 - To show the results :
  perf kvm stat report --event=hcall

The result shows the number of hypervisor calls from the guest grouped
by their respective reasons displayed with the frequency.

This patch makes use of two additional tracepoints
"kvm_hv:kvm_hcall_enter" and "kvm_hv:kvm_hcall_exit". To map the hcall
codes to their respective names, it needs a mapping. Such mapping is
added in this patch in book3s_hcalls.h.

 # pgrep qemu
A sample output :
19378
60515

2 VMs running.

 # perf kvm stat record -a
^C[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 4.153 MB perf.data.guest (39624
samples) ]

 # perf kvm stat report -p 60515 --event=hcall

Analyze events for all VMs, all VCPUs:

    HCALL-EVENT Samples Samples% Time% MinTime MaxTime  AvgTime

          H_IPI     822  66.08% 88.10% 0.63us  11.38us 2.05us (+- 1.42%)
     H_SEND_CRQ     144  11.58%  3.77% 0.41us   0.88us 0.50us (+- 1.47%)
   H_VIO_SIGNAL     118   9.49%  2.86% 0.37us   0.83us 0.47us (+- 1.43%)
H_PUT_TERM_CHAR      76   6.11%  2.07% 0.37us   0.90us 0.52us (+- 2.43%)
H_GET_TERM_CHAR      74   5.95%  2.23% 0.37us   1.70us 0.58us (+- 4.77%)
         H_RTAS       6   0.48%  0.85% 1.10us   9.25us 2.70us (+-48.57%)
      H_PERFMON       4   0.32%  0.12% 0.41us   0.96us 0.59us (+-20.92%)

Total Samples:1244, Total events handled time:1916.69us.

Signed-off-by: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Scott  Wood <scottwood@freescale.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1453962787-15376-4-git-send-email-hemant@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 64 insertions, 1 deletions

diff --git a/tools/perf/arch/powerpc/util/kvm-stat.c b/tools/perf/arch/powerpc/util/kvm-stat.c
index 27bc559b8b3a..74eee30398f8 100644
--- a/tools/perf/arch/powerpc/util/kvm-stat.c
+++ b/tools/perf/arch/powerpc/util/kvm-stat.c
@@ -1,9 +1,11 @@
 #include "util/kvm-stat.h"
 #include "util/parse-events.h"
+#include "util/debug.h"
 
 #include "book3s_hv_exits.h"
+#include "book3s_hcalls.h"
 
-#define NR_TPS 2
+#define NR_TPS 4
 
 const char *vcpu_id_str = "vcpu_id";
 const int decode_str_len = 40;
@@ -11,17 +13,77 @@ const char *kvm_entry_trace = "kvm_hv:kvm_guest_enter";
 const char *kvm_exit_trace = "kvm_hv:kvm_guest_exit";
 
 define_exit_reasons_table(hv_exit_reasons, kvm_trace_symbol_exit);
+define_exit_reasons_table(hcall_reasons, kvm_trace_symbol_hcall);
 
 /* Tracepoints specific to ppc_book3s_hv */
 const char *ppc_book3s_hv_kvm_tp[] = {
 	"kvm_hv:kvm_guest_enter",
 	"kvm_hv:kvm_guest_exit",
+	"kvm_hv:kvm_hcall_enter",
+	"kvm_hv:kvm_hcall_exit",
+	NULL,
 };
 
 /* 1 extra placeholder for NULL */
 const char *kvm_events_tp[NR_TPS + 1];
 const char *kvm_exit_reason;
 
+static void hcall_event_get_key(struct perf_evsel *evsel,
+				struct perf_sample *sample,
+				struct event_key *key)
+{
+	key->info = 0;
+	key->key = perf_evsel__intval(evsel, sample, "req");
+}
+
+static const char *get_hcall_exit_reason(u64 exit_code)
+{
+	struct exit_reasons_table *tbl = hcall_reasons;
+
+	while (tbl->reason != NULL) {
+		if (tbl->exit_code == exit_code)
+			return tbl->reason;
+		tbl++;
+	}
+
+	pr_debug("Unknown hcall code: %lld\n",
+	       (unsigned long long)exit_code);
+	return "UNKNOWN";
+}
+
+static bool hcall_event_end(struct perf_evsel *evsel,
+			    struct perf_sample *sample __maybe_unused,
+			    struct event_key *key __maybe_unused)
+{
+	return (!strcmp(evsel->name, kvm_events_tp[3]));
+}
+
+static bool hcall_event_begin(struct perf_evsel *evsel,
+			      struct perf_sample *sample, struct event_key *key)
+{
+	if (!strcmp(evsel->name, kvm_events_tp[2])) {
+		hcall_event_get_key(evsel, sample, key);
+		return true;
+	}
+
+	return false;
+}
+static void hcall_event_decode_key(struct perf_kvm_stat *kvm __maybe_unused,
+				   struct event_key *key,
+				   char *decode)
+{
+	const char *hcall_reason = get_hcall_exit_reason(key->key);
+
+	scnprintf(decode, decode_str_len, "%s", hcall_reason);
+}
+
+static struct kvm_events_ops hcall_events = {
+	.is_begin_event = hcall_event_begin,
+	.is_end_event = hcall_event_end,
+	.decode_key = hcall_event_decode_key,
+	.name = "HCALL-EVENT",
+};
+
 static struct kvm_events_ops exit_events = {
 	.is_begin_event = exit_event_begin,
 	.is_end_event = exit_event_end,
@@ -31,6 +93,7 @@ static struct kvm_events_ops exit_events = {
 
 struct kvm_reg_events_ops kvm_reg_events_ops[] = {
 	{ .name = "vmexit", .ops = &exit_events },
+	{ .name = "hcall", .ops = &hcall_events },
 	{ NULL, NULL },
 };