arm/arm64: KVM: Add exit reaons to kvm_exit event tracing

This patch extends trace_kvm_exit() to include KVM exit reasons
(i.e. EC of HSR). The tracing function then dumps both exit reason
and PC of vCPU, shown as the following. Tracing tools can use this
new exit_reason field to better understand the behavior of guest VMs.

886.301252: kvm_exit:             HSR_EC: 0x0024, PC: 0xfffffe0000506b28
Signed-off-by: Wei Huang <wei@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

arch/arm/kvm/arm.c

@@ -540,7 +540,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 
 		vcpu->mode = OUTSIDE_GUEST_MODE;
 		kvm_guest_exit();
-		trace_kvm_exit(*vcpu_pc(vcpu));
+		trace_kvm_exit(kvm_vcpu_trap_get_class(vcpu), *vcpu_pc(vcpu));
 		/*
 		 * We may have taken a host interrupt in HYP mode (ie
 		 * while executing the guest). This interrupt is still

arch/arm/kvm/trace.h

@@ -25,18 +25,22 @@ TRACE_EVENT(kvm_entry,
 );
 
 TRACE_EVENT(kvm_exit,
-	TP_PROTO(unsigned long vcpu_pc),
-	TP_ARGS(vcpu_pc),
+	TP_PROTO(unsigned int exit_reason, unsigned long vcpu_pc),
+	TP_ARGS(exit_reason, vcpu_pc),
 
 	TP_STRUCT__entry(
+		__field(	unsigned int,	exit_reason	)
 		__field(	unsigned long,	vcpu_pc		)
 	),
 
 	TP_fast_assign(
+		__entry->exit_reason		= exit_reason;
 		__entry->vcpu_pc		= vcpu_pc;
 	),
 
-	TP_printk("PC: 0x%08lx", __entry->vcpu_pc)
+	TP_printk("HSR_EC: 0x%04x, PC: 0x%08lx",
+		  __entry->exit_reason,
+		  __entry->vcpu_pc)
 );
 
 TRACE_EVENT(kvm_guest_fault,