KVM: nVMX: Read EXIT_QUAL and INTR_INFO only when needed for nested exit

Read vmcs.EXIT_QUALIFICATION and vmcs.VM_EXIT_INTR_INFO only if the
VM-Exit is being reflected to L1 now that they are no longer passed
directly to the kvm_nested_vmexit tracepoint.

No functional change intended.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200923201349.16097-8-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/nested.c

@@ -5934,9 +5934,6 @@ bool nested_vmx_reflect_vmexit(struct kvm_vcpu *vcpu)
 		goto reflect_vmexit;
 	}
 
-	exit_intr_info = vmx_get_intr_info(vcpu);
-	exit_qual = vmx_get_exit_qual(vcpu);
-
 	trace_kvm_nested_vmexit(exit_reason, vcpu, KVM_ISA_VMX);
 
 	/* If L0 (KVM) wants the exit, it trumps L1's desires. */
@@ -5953,12 +5950,14 @@ bool nested_vmx_reflect_vmexit(struct kvm_vcpu *vcpu)
 	 * need to be synthesized by querying the in-kernel LAPIC, but external
 	 * interrupts are never reflected to L1 so it's a non-issue.
 	 */
+	exit_intr_info = vmx_get_intr_info(vcpu);
 	if (is_exception_with_error_code(exit_intr_info)) {
 		struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
 
 		vmcs12->vm_exit_intr_error_code =
 			vmcs_read32(VM_EXIT_INTR_ERROR_CODE);
 	}
+	exit_qual = vmx_get_exit_qual(vcpu);
 
 reflect_vmexit:
 	nested_vmx_vmexit(vcpu, exit_reason, exit_intr_info, exit_qual);