[PATCH RESEND v4 1/2] perf/kvm: Port perf kvm to powerpc

From: Srikar Dronamraju <redacted>

perf kvm can be used to analyze guest exit reasons. This support already
exists in x86. Hence, porting it to powerpc.

 - To trace KVM events :
  perf kvm stat record
  If many guests are running, we can track for a specific guest by using
  --pid as in : perf kvm stat record --pid <pid>

 - To see the results :
  perf kvm stat report

The result shows the number of exits (from the guest context to
host/hypervisor context) grouped by their respective exit reasons with
their frequency.

This patch makes use of the guest exit reasons available in
"trace_book3s.h". It records on two already available tracepoints :
"kvm_hv:kvm_guest_exit" and "kvm_hv:kvm_guest_enter".

Note : This patch has a dependency on the patch "kvm/powerpc: Export
kvm exit reasons" which exports the KVM exit reasons through the uapi.

Here is a sample o/p:
 # pgrep qemu
19378
60515

2 Guests are running on the host.

 # 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
Analyze events for pid(s) 60515, all VCPUs:

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

H_DATA_STORAGE       5006    35.30%     0.13%      1.94us     49.46us     12.37us ( +-   0.52% )
HV_DECREMENTER       4457    31.43%     0.02%      0.72us     16.14us      1.91us ( +-   0.96% )
       SYSCALL       2690    18.97%     0.10%      2.84us    528.24us     18.29us ( +-   3.75% )
RETURN_TO_HOST       1789    12.61%    99.76%      1.58us 672791.91us  27470.23us ( +-   3.00% )
      EXTERNAL        240     1.69%     0.00%      0.69us     10.67us      1.33us ( +-   5.34% )

Total Samples:14182, Total events handled time:49264158.30us.

Signed-off-by: Srikar Dronamraju <redacted>
Signed-off-by: Hemant Kumar <redacted>
---
Patch Resend :
- Added few more people to cc list.
- Rebased it to current tip.
Changes :
- Moved the uapi related changes to arch/powerpc patchset.

This patch has a dependency on :
http://www.mail-archive.com/linuxppc-dev@lists.ozlabs.org/msg90506.html
which exports the kvm exit reasons.

 tools/perf/arch/powerpc/Makefile        |  1 +
 tools/perf/arch/powerpc/util/Build      |  1 +
 tools/perf/arch/powerpc/util/kvm-stat.c | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+)
 create mode 100644 tools/perf/arch/powerpc/util/kvm-stat.c

diff --git a/tools/perf/arch/powerpc/Makefile b/tools/perf/arch/powerpc/Makefile
index 7fbca17..21322e0 100644
--- a/tools/perf/arch/powerpc/Makefile
+++ b/tools/perf/arch/powerpc/Makefile

@@ -1,3 +1,4 @@
 ifndef NO_DWARF
 PERF_HAVE_DWARF_REGS := 1
 endif
+HAVE_KVM_STAT_SUPPORT := 1

diff --git a/tools/perf/arch/powerpc/util/Build b/tools/perf/arch/powerpc/util/Build
index 7b8b0d1..c8fe207 100644
--- a/tools/perf/arch/powerpc/util/Build
+++ b/tools/perf/arch/powerpc/util/Build

@@ -1,5 +1,6 @@
 libperf-y += header.o
 libperf-y += sym-handling.o
+libperf-y += kvm-stat.o
 
 libperf-$(CONFIG_DWARF) += dwarf-regs.o
 libperf-$(CONFIG_DWARF) += skip-callchain-idx.o

diff --git a/tools/perf/arch/powerpc/util/kvm-stat.c b/tools/perf/arch/powerpc/util/kvm-stat.c
new file mode 100644
index 0000000..24e06bf
--- /dev/null
+++ b/tools/perf/arch/powerpc/util/kvm-stat.c

@@ -0,0 +1,33 @@
+#include "../../util/kvm-stat.h"
+#include <asm/kvm_perf_book3s.h>
+
+define_exit_reasons_table(hv_exit_reasons, kvm_trace_symbol_exit);
+
+static struct kvm_events_ops exit_events = {
+	.is_begin_event = exit_event_begin,
+	.is_end_event = exit_event_end,
+	.decode_key = exit_event_decode_key,
+	.name = "VM-EXIT"
+};
+
+const char *const kvm_events_tp[] = {
+	"kvm_hv:kvm_guest_exit",
+	"kvm_hv:kvm_guest_enter",
+	NULL,
+};
+
+struct kvm_reg_events_ops kvm_reg_events_ops[] = {
+	{ .name = "vmexit", .ops = &exit_events },
+	{ NULL, NULL },
+};
+
+const char * const kvm_skip_events[] = {
+	NULL,
+};
+
+int cpu_isa_init(struct perf_kvm_stat *kvm, const char *cpuid __maybe_unused)
+{
+	kvm->exit_reasons = hv_exit_reasons;
+	kvm->exit_reasons_isa = "HV";
+	return 0;
+}

-- 
1.9.3

powerpc provides hcall events that also provides insights into guest
behaviour. Enhance perf kvm 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". It uses the
pSeries hypervisor codes exported through uapi to classify the hcalls
into their respective reasons.

Note : This patch has a dependency on "kvm/powerpc: Export HCALL reason
codes" which exports HCALL reasons through uapi.

 # 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 pid(s) 60515, all VCPUs:

         HCALL-EVENT    Samples  Samples%     Time%    Min Time    Max Time         Avg time

        H_VIO_SIGNAL       1034    38.44%    15.77%      0.36us      1.59us      0.44us ( +-   0.66% )
          H_SEND_CRQ        652    24.24%    10.97%      0.39us      1.84us      0.49us ( +-   1.20% )
               H_IPI        523    19.44%    62.05%      1.35us     19.70us      3.44us ( +-   2.88% )
     H_PUT_TERM_CHAR        411    15.28%     8.03%      0.38us      3.77us      0.57us ( +-   1.61% )
     H_GET_TERM_CHAR         50     1.86%     0.99%      0.40us      0.98us      0.57us ( +-   3.37% )
               H_EOI         20     0.74%     2.19%      2.22us      4.72us      3.17us ( +-   5.96% )

Total Samples:2690, Total events handled time:2896.94us.

Signed-off-by: Hemant Kumar <redacted>
---
Changes:
- Moved the uapi related changes to arch/powerpc side patchset.

This patch has a dependency on :
http://www.mail-archive.com/linuxppc-dev@lists.ozlabs.org/msg90507.html
which export hcall reasons through uapi.

 tools/perf/arch/powerpc/util/kvm-stat.c | 61 +++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/tools/perf/arch/powerpc/util/kvm-stat.c b/tools/perf/arch/powerpc/util/kvm-stat.c
index 24e06bf..0d3ea47 100644
--- a/tools/perf/arch/powerpc/util/kvm-stat.c
+++ b/tools/perf/arch/powerpc/util/kvm-stat.c

@@ -1,7 +1,9 @@
 #include "../../util/kvm-stat.h"
 #include <asm/kvm_perf_book3s.h>
+#include "../../util/debug.h"
 
 define_exit_reasons_table(hv_exit_reasons, kvm_trace_symbol_exit);
+define_exit_reasons_table(hcall_reasons, kvm_trace_symbol_hcall);
 
 static struct kvm_events_ops exit_events = {
 	.is_begin_event = exit_event_begin,

@@ -10,14 +12,73 @@ static struct kvm_events_ops exit_events = {
 	.name = "VM-EXIT"
 };
 
+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, KVM_HCALL_REASON);
+}
+
+static const char *get_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_err("Unknown kvm hcall exit 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_HCALL_EXIT_TRACE));
+}
+
+static bool hcall_event_begin(struct perf_evsel *evsel,
+			      struct perf_sample *sample, struct event_key *key)
+{
+	if (!strcmp(evsel->name, KVM_HCALL_ENTRY_TRACE)) {
+		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_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",
+};
+
 const char *const kvm_events_tp[] = {
 	"kvm_hv:kvm_guest_exit",
 	"kvm_hv:kvm_guest_enter",
+	"kvm_hv:kvm_hcall_enter",
+	"kvm_hv:kvm_hcall_exit",
 	NULL,
 };
 
 struct kvm_reg_events_ops kvm_reg_events_ops[] = {
 	{ .name = "vmexit", .ops = &exit_events },
+	{ .name = "hcall", .ops = &hcall_events },
 	{ NULL, NULL },
 };
 

-- 
1.9.3