MIPS: KVM: Add guest mode switch trace events

Add a few trace events for entering and coming out of guest mode, as well
as re-entering it from a guest exit exception.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: kvm@vger.kernel.org
Cc: linux-mips@linux-mips.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/mips/kvm/mips.c

@@ -410,7 +410,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 	/* Disable hardware page table walking while in guest */
 	htw_stop();
 
+	trace_kvm_enter(vcpu);
 	r = vcpu->arch.vcpu_run(run, vcpu);
+	trace_kvm_out(vcpu);
 
 	/* Re-enable HTW before enabling interrupts */
 	htw_start();
@@ -1389,6 +1391,8 @@ int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
 	}
 
 	if (ret == RESUME_GUEST) {
+		trace_kvm_reenter(vcpu);
+
 		/*
 		 * If FPU / MSA are enabled (i.e. the guest's FPU / MSA context
 		 * is live), restore FCR31 / MSACSR.

arch/mips/kvm/trace.h

@@ -17,6 +17,54 @@
 #define TRACE_INCLUDE_PATH .
 #define TRACE_INCLUDE_FILE trace
 
+/*
+ * Tracepoints for VM enters
+ */
+TRACE_EVENT(kvm_enter,
+	    TP_PROTO(struct kvm_vcpu *vcpu),
+	    TP_ARGS(vcpu),
+	    TP_STRUCT__entry(
+			__field(unsigned long, pc)
+	    ),
+
+	    TP_fast_assign(
+			__entry->pc = vcpu->arch.pc;
+	    ),
+
+	    TP_printk("PC: 0x%08lx",
+		      __entry->pc)
+);
+
+TRACE_EVENT(kvm_reenter,
+	    TP_PROTO(struct kvm_vcpu *vcpu),
+	    TP_ARGS(vcpu),
+	    TP_STRUCT__entry(
+			__field(unsigned long, pc)
+	    ),
+
+	    TP_fast_assign(
+			__entry->pc = vcpu->arch.pc;
+	    ),
+
+	    TP_printk("PC: 0x%08lx",
+		      __entry->pc)
+);
+
+TRACE_EVENT(kvm_out,
+	    TP_PROTO(struct kvm_vcpu *vcpu),
+	    TP_ARGS(vcpu),
+	    TP_STRUCT__entry(
+			__field(unsigned long, pc)
+	    ),
+
+	    TP_fast_assign(
+			__entry->pc = vcpu->arch.pc;
+	    ),
+
+	    TP_printk("PC: 0x%08lx",
+		      __entry->pc)
+);
+
 /* The first 32 exit reasons correspond to Cause.ExcCode */
 #define KVM_TRACE_EXIT_INT		 0
 #define KVM_TRACE_EXIT_TLBMOD		 1