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Subject[PATCH v1 4/5] perf,kvm/arm64: Add stat support on arm64
Date
'perf kvm stat report/record' generates a statistical analysis of KVM
events and can be used to analyze guest exit reasons. This patch tries
to add stat support on arm64.

We have a mapping between guest's "exit_code" and "exit_reason" which
already exists under arch/arm64/include/asm/ (kvm_arm_exception_type),
and we've used it to report guest's exit type through trace_kvm_exit().
Copy kvm_arm_exception_type into aarch64_guest_exits.h, thus export it
to userspace.

It records on two available KVM tracepoints for arm64: "kvm:kvm_entry"
and "kvm:kvm_exit", and reports statistical data which includes events
handles time, samples, and so on.

A simple test go below:

# pgrep qemu
6039
9937

# ./tools/perf/perf kvm stat record -p 6039
[ perf record: Woken up 3 times to write data ]
[ perf record: Captured and wrote 15.629 MB perf.data.guest (199063 samples) ]

# ./tools/perf/perf kvm stat report --event=vmexit

Analyze events for all VMs, all VCPUs:

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

TRAP 49040 97.15% 100.00% 2.60us 4072.98us 3431.60us ( +- 0.17% )
IRQ 1437 2.85% 0.00% 0.90us 24.56us 2.06us ( +- 1.37% )

Total Samples:50477, Total events handled time:168288630.04us.

Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Christoffer Dall <christoffer.dall@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
---
tools/perf/arch/arm64/Makefile | 2 +
tools/perf/arch/arm64/util/Build | 1 +
tools/perf/arch/arm64/util/aarch64_guest_exits.h | 23 +++++++++
tools/perf/arch/arm64/util/kvm-stat.c | 60 ++++++++++++++++++++++++
4 files changed, 86 insertions(+)
create mode 100644 tools/perf/arch/arm64/util/aarch64_guest_exits.h
create mode 100644 tools/perf/arch/arm64/util/kvm-stat.c

diff --git a/tools/perf/arch/arm64/Makefile b/tools/perf/arch/arm64/Makefile
index dbef716..172146e 100644
--- a/tools/perf/arch/arm64/Makefile
+++ b/tools/perf/arch/arm64/Makefile
@@ -2,6 +2,8 @@
ifndef NO_DWARF
PERF_HAVE_DWARF_REGS := 1
endif
+
+HAVE_KVM_STAT_SUPPORT := 1
PERF_HAVE_JITDUMP := 1
PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET := 1

diff --git a/tools/perf/arch/arm64/util/Build b/tools/perf/arch/arm64/util/Build
index 3cde540..d136674 100644
--- a/tools/perf/arch/arm64/util/Build
+++ b/tools/perf/arch/arm64/util/Build
@@ -1,5 +1,6 @@
perf-y += header.o
perf-y += sym-handling.o
+perf-y += kvm-stat.o
perf-$(CONFIG_DWARF) += dwarf-regs.o
perf-$(CONFIG_LOCAL_LIBUNWIND) += unwind-libunwind.o
perf-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
diff --git a/tools/perf/arch/arm64/util/aarch64_guest_exits.h b/tools/perf/arch/arm64/util/aarch64_guest_exits.h
new file mode 100644
index 0000000..a8ca4b8
--- /dev/null
+++ b/tools/perf/arch/arm64/util/aarch64_guest_exits.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef ARCH_PERF_AARCH64_GUEST_EXITS_H
+#define ARCH_PERF_AARCH64_GUEST_EXITS_H
+
+/* virt.h */
+/* Error returned when an invalid stub number is passed into x0 */
+#define HVC_STUB_ERR 0xbadca11
+
+/* kvm_asm.h */
+#define ARM_EXCEPTION_IRQ 0
+#define ARM_EXCEPTION_EL1_SERROR 1
+#define ARM_EXCEPTION_TRAP 2
+#define ARM_EXCEPTION_IL 3
+/* The hyp-stub will return this for any kvm_call_hyp() call */
+#define ARM_EXCEPTION_HYP_GONE HVC_STUB_ERR
+
+#define kvm_arm_exception_type \
+ {ARM_EXCEPTION_IRQ, "IRQ" }, \
+ {ARM_EXCEPTION_EL1_SERROR, "SERROR" }, \
+ {ARM_EXCEPTION_TRAP, "TRAP" }, \
+ {ARM_EXCEPTION_HYP_GONE, "HYP_GONE" }
+
+#endif
diff --git a/tools/perf/arch/arm64/util/kvm-stat.c b/tools/perf/arch/arm64/util/kvm-stat.c
new file mode 100644
index 0000000..5804bc2
--- /dev/null
+++ b/tools/perf/arch/arm64/util/kvm-stat.c
@@ -0,0 +1,60 @@
+/*
+ * Arch specific functions for perf kvm stat.
+ *
+ * Copyright (c) 2019 - Huawei Technologies Co., Ltd.
+ * Author(s): Zenghui Yu <yuzenghui@huawei.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+#include <errno.h>
+#include "../../util/kvm-stat.h"
+#include "../../util/evsel.h"
+#include "aarch64_guest_exits.h"
+
+define_exit_reasons_table(arm64_exit_reasons, kvm_arm_exception_type);
+
+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 *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_events_tp[] = {
+ "kvm:kvm_entry",
+ "kvm:kvm_exit",
+ 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 = arm64_exit_reasons;
+ kvm->exit_reasons_isa = "aarch64";
+
+ return 0;
+}
--
1.8.3.1

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