arm64: KVM: Add trapped system register access tracepoint

We're pretty blind when it comes to system register tracing,
and rely on the ESR value displayed by kvm_handle_sys, which
isn't much.

Instead, let's add an actual name to the sysreg entries, so that
we can finally print it as we're about to perform the access
itself.

The new tracepoint is conveniently called kvm_sys_access.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm64/kvm/sys_regs.c

@@ -1850,6 +1850,8 @@ static void perform_access(struct kvm_vcpu *vcpu,
 			   struct sys_reg_params *params,
 			   const struct sys_reg_desc *r)
 {
+	trace_kvm_sys_access(*vcpu_pc(vcpu), params, r);
+
 	/*
 	 * Not having an accessor means that we have configured a trap
 	 * that we don't know how to handle. This certainly qualifies