kvm: add tracepoint for fast mmio

Cc: Gleb Natapov <gleb@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/trace.h

@@ -128,6 +128,24 @@ TRACE_EVENT(kvm_pio,
 		  __entry->count > 1 ? "(...)" : "")
 );
 
+/*
+ * Tracepoint for fast mmio.
+ */
+TRACE_EVENT(kvm_fast_mmio,
+	TP_PROTO(u64 gpa),
+	TP_ARGS(gpa),
+
+	TP_STRUCT__entry(
+		__field(u64,	gpa)
+	),
+
+	TP_fast_assign(
+		__entry->gpa		= gpa;
+	),
+
+	TP_printk("fast mmio at gpa 0x%llx", __entry->gpa)
+);
+
 /*
  * Tracepoint for cpuid.
  */

arch/x86/kvm/vmx.c

@@ -5756,6 +5756,7 @@ static int handle_ept_misconfig(struct kvm_vcpu *vcpu)
 	gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
 	if (!kvm_io_bus_write(vcpu, KVM_FAST_MMIO_BUS, gpa, 0, NULL)) {
 		skip_emulated_instruction(vcpu);
+		trace_kvm_fast_mmio(gpa);
 		return 1;
 	}
 

arch/x86/kvm/x86.c

@@ -8070,6 +8070,7 @@ bool kvm_arch_has_noncoherent_dma(struct kvm *kvm)
 EXPORT_SYMBOL_GPL(kvm_arch_has_noncoherent_dma);
 
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
+EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_page_fault);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_msr);