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

[Leo Yan]

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@xxxxxxxxxx>
---
 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