Dell XPS 8500 Intel VT-d support?

Hi,

I just purchased a Dell XPS 8500 with the Core i7 3770 processor. According to Intel, this processor supports VT-d. Furthermore, the used chipset (H77) should also support VT-d.

I did enable Intel Virtualization Technologies in the BIOS. After installing Ubuntu 12.04 (and Xen on top of it), I tried "xm dmesg"

(XEN) Intel VT-d Snoop Control not enabled.
(XEN) Intel VT-d Dom0 DMA Passthrough not enabled.
(XEN) Intel VT-d Queued Invalidation enabled.
(XEN) Intel VT-d Interrupt Remapping enabled.
(XEN) Intel VT-d Shared EPT tables not enabled.
(XEN) I/O virtualisation enabled

Is the output. I am now wondering what else I have to do to enable the DMA passthrough? How can I verify that the hardware supports VT-d? 

Thanks for help!!