linux-kernel - [PATCH v1 1/3] KVM: arm64: Dynamically register callback for tracepoints

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Date:   Sat,  5 Nov 2022 07:23:09 +0000
From:   Leo Yan <leo.yan@...aro.org>
To:     Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        John Garry <john.garry@...wei.com>,
        James Clark <james.clark@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        kvmarm@...ts.cs.columbia.edu, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org
Cc:     Leo Yan <leo.yan@...aro.org>
Subject: [PATCH v1 1/3] KVM: arm64: Dynamically register callback for tracepoints

This commit doesn't change any functionality but only refactoring.

It registers callbacks for tracepoints dynamically, with this way, the
existed trace events (in this case kvm_entry and kvm_exit) are kept.
This is a preparation to add new trace events in later patch.

Signed-off-by: Leo Yan <leo.yan@...aro.org>
---
 arch/arm64/kvm/Makefile    |  2 +-
 arch/arm64/kvm/arm.c       |  4 ++--
 arch/arm64/kvm/trace.c     | 29 +++++++++++++++++++++++++++++
 arch/arm64/kvm/trace_arm.h |  8 ++++++++
 4 files changed, 40 insertions(+), 3 deletions(-)
 create mode 100644 arch/arm64/kvm/trace.c

diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 5e33c2d4645a..4e641d2df7ad 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -14,7 +14,7 @@ kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \
 	 inject_fault.o va_layout.o handle_exit.o \
 	 guest.o debug.o reset.o sys_regs.o stacktrace.o \
 	 vgic-sys-reg-v3.o fpsimd.o pkvm.o \
-	 arch_timer.o trng.o vmid.o \
+	 arch_timer.o trng.o vmid.o trace.o \
 	 vgic/vgic.o vgic/vgic-init.o \
 	 vgic/vgic-irqfd.o vgic/vgic-v2.o \
 	 vgic/vgic-v3.o vgic/vgic-v4.o \
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 94d33e296e10..03ed5f6c92bc 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -917,7 +917,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		/**************************************************************
 		 * Enter the guest
 		 */
-		trace_kvm_entry(*vcpu_pc(vcpu));
+		trace_kvm_entry_tp(vcpu);
 		guest_timing_enter_irqoff();
 
 		ret = kvm_arm_vcpu_enter_exit(vcpu);
@@ -974,7 +974,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
 		local_irq_enable();
 
-		trace_kvm_exit(ret, kvm_vcpu_trap_get_class(vcpu), *vcpu_pc(vcpu));
+		trace_kvm_exit_tp(ret, vcpu);
 
 		/* Exit types that need handling before we can be preempted */
 		handle_exit_early(vcpu, ret);
diff --git a/arch/arm64/kvm/trace.c b/arch/arm64/kvm/trace.c
new file mode 100644
index 000000000000..d25a3db994e2
--- /dev/null
+++ b/arch/arm64/kvm/trace.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/init.h>
+#include <linux/tracepoint.h>
+
+#include <asm/kvm_emulate.h>
+
+#include "trace_arm.h"
+
+static void kvm_entry_tp(void *data, struct kvm_vcpu *vcpu)
+{
+	if (trace_kvm_entry_enabled())
+		trace_kvm_entry(*vcpu_pc(vcpu));
+}
+
+static void kvm_exit_tp(void *data, int ret, struct kvm_vcpu *vcpu)
+{
+	if (trace_kvm_exit_enabled())
+		trace_kvm_exit(ret, kvm_vcpu_trap_get_class(vcpu),
+			       *vcpu_pc(vcpu));
+}
+
+static int __init kvm_tp_init(void)
+{
+	register_trace_kvm_entry_tp(kvm_entry_tp, NULL);
+	register_trace_kvm_exit_tp(kvm_exit_tp, NULL);
+	return 0;
+}
+
+core_initcall(kvm_tp_init)
diff --git a/arch/arm64/kvm/trace_arm.h b/arch/arm64/kvm/trace_arm.h
index 33e4e7dd2719..ef02ae93b28b 100644
--- a/arch/arm64/kvm/trace_arm.h
+++ b/arch/arm64/kvm/trace_arm.h
@@ -11,6 +11,10 @@
 /*
  * Tracepoints for entry/exit to guest
  */
+DECLARE_TRACE(kvm_entry_tp,
+	TP_PROTO(struct kvm_vcpu *vcpu),
+	TP_ARGS(vcpu));
+
 TRACE_EVENT(kvm_entry,
 	TP_PROTO(unsigned long vcpu_pc),
 	TP_ARGS(vcpu_pc),
@@ -26,6 +30,10 @@ TRACE_EVENT(kvm_entry,
 	TP_printk("PC: 0x%016lx", __entry->vcpu_pc)
 );
 
+DECLARE_TRACE(kvm_exit_tp,
+	TP_PROTO(int ret, struct kvm_vcpu *vcpu),
+	TP_ARGS(ret, vcpu));
+
 TRACE_EVENT(kvm_exit,
 	TP_PROTO(int ret, unsigned int esr_ec, unsigned long vcpu_pc),
 	TP_ARGS(ret, esr_ec, vcpu_pc),
-- 
2.34.1