[RFC PATCH V3 3/4] RISC-V: paravirt: pvqspinlock: Add trace point for pv_kick/wait

[guoren@kernel.org]

From: "Guo Ren (Alibaba DAMO Academy)" <guoren@kernel.org>

Add trace point for pv_kick&wait, here is the output:

ls /sys/kernel/debug/tracing/events/paravirt/
 enable   filter   pv_kick  pv_wait

cat /sys/kernel/debug/tracing/trace
 entries-in-buffer/entries-written: 33927/33927   #P:12

                                _-----=> irqs-off/BH-disabled
                               / _----=> need-resched
                              | / _---=> hardirq/softirq
                              || / _--=> preempt-depth
                              ||| / _-=> migrate-disable
                              |||| /     delay
           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
              | |         |   |||||     |         |
             sh-100     [001] d..2.    28.312294: pv_wait: cpu 1 out of wfi
         <idle>-0       [000] d.h4.    28.322030: pv_kick: cpu 0 kick target cpu 1
             sh-100     [001] d..2.    30.982631: pv_wait: cpu 1 out of wfi
         <idle>-0       [000] d.h4.    30.993289: pv_kick: cpu 0 kick target cpu 1
             sh-100     [002] d..2.    44.987573: pv_wait: cpu 2 out of wfi
         <idle>-0       [000] d.h4.    44.989000: pv_kick: cpu 0 kick target cpu 2
         <idle>-0       [003] d.s3.    51.593978: pv_kick: cpu 3 kick target cpu 4
      rcu_sched-15      [004] d..2.    51.595192: pv_wait: cpu 4 out of wfi
lock_torture_wr-115     [004] ...2.    52.656482: pv_kick: cpu 4 kick target cpu 2
lock_torture_wr-113     [002] d..2.    52.659146: pv_wait: cpu 2 out of wfi
lock_torture_wr-114     [008] d..2.    52.659507: pv_wait: cpu 8 out of wfi
lock_torture_wr-114     [008] d..2.    52.663503: pv_wait: cpu 8 out of wfi
lock_torture_wr-113     [002] ...2.    52.666128: pv_kick: cpu 2 kick target cpu 8
lock_torture_wr-114     [008] d..2.    52.667261: pv_wait: cpu 8 out of wfi
lock_torture_wr-114     [009] .n.2.    53.141515: pv_kick: cpu 9 kick target cpu 11
lock_torture_wr-113     [002] d..2.    53.143339: pv_wait: cpu 2 out of wfi
lock_torture_wr-116     [007] d..2.    53.143412: pv_wait: cpu 7 out of wfi
lock_torture_wr-118     [000] d..2.    53.143457: pv_wait: cpu 0 out of wfi
lock_torture_wr-115     [008] d..2.    53.143481: pv_wait: cpu 8 out of wfi
lock_torture_wr-117     [011] d..2.    53.143522: pv_wait: cpu 11 out of wfi
lock_torture_wr-117     [011] ...2.    53.143987: pv_kick: cpu 11 kick target cpu 8
lock_torture_wr-115     [008] ...2.    53.144269: pv_kick: cpu 8 kick target cpu 7

Reviewed-by: Leonardo Bras <leobras@redhat.com>
Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guoren@kernel.org>
---
 arch/riscv/kernel/qspinlock_paravirt.c        |  7 +++
 .../kernel/trace_events_filter_paravirt.h     | 60 +++++++++++++++++++
 2 files changed, 67 insertions(+)
 create mode 100644 arch/riscv/kernel/trace_events_filter_paravirt.h

diff --git a/arch/riscv/kernel/qspinlock_paravirt.c b/arch/riscv/kernel/qspinlock_paravirt.c
index 299dddaa14b8..cae991139abe 100644
--- a/arch/riscv/kernel/qspinlock_paravirt.c
+++ b/arch/riscv/kernel/qspinlock_paravirt.c
@@ -9,8 +9,13 @@
 #include <asm/qspinlock_paravirt.h>
 #include <asm/sbi.h>
 
+#define CREATE_TRACE_POINTS
+#include "trace_events_filter_paravirt.h"
+
 void pv_kick(int cpu)
 {
+	trace_pv_kick(smp_processor_id(), cpu);
+
 	sbi_ecall(SBI_EXT_PVLOCK, SBI_EXT_PVLOCK_KICK_CPU,
 		  cpuid_to_hartid_map(cpu), 0, 0, 0, 0, 0);
 	return;
@@ -28,6 +33,8 @@ void pv_wait(u8 *ptr, u8 val)
 		goto out;
 
 	wait_for_interrupt();
+
+	trace_pv_wait(smp_processor_id());
 out:
 	local_irq_restore(flags);
 }
diff --git a/arch/riscv/kernel/trace_events_filter_paravirt.h b/arch/riscv/kernel/trace_events_filter_paravirt.h
new file mode 100644
index 000000000000..db5e702a1f12
--- /dev/null
+++ b/arch/riscv/kernel/trace_events_filter_paravirt.h
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c), 2025 Alibaba Damo Academy
+ * Authors:
+ *	Guo Ren <guoren@kernel.org>
+ */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM paravirt
+
+#if !defined(_TRACE_PARAVIRT_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_PARAVIRT_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(pv_kick,
+	TP_PROTO(int cpu, int target),
+	TP_ARGS(cpu, target),
+
+	TP_STRUCT__entry(
+		__field(int, cpu)
+		__field(int, target)
+	),
+
+	TP_fast_assign(
+		__entry->cpu = cpu;
+		__entry->target = target;
+	),
+
+	TP_printk("cpu %d pv_kick target cpu %d",
+		__entry->cpu,
+		__entry->target
+	)
+);
+
+TRACE_EVENT(pv_wait,
+	TP_PROTO(int cpu),
+	TP_ARGS(cpu),
+
+	TP_STRUCT__entry(
+		__field(int, cpu)
+	),
+
+	TP_fast_assign(
+		__entry->cpu = cpu;
+	),
+
+	TP_printk("cpu %d out of wfi",
+		__entry->cpu
+	)
+);
+
+#endif /* _TRACE_PARAVIRT_H || TRACE_HEADER_MULTI_READ */
+
+#undef TRACE_INCLUDE_PATH
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_PATH ../../../arch/riscv/kernel/
+#define TRACE_INCLUDE_FILE trace_events_filter_paravirt
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
-- 
2.40.1