virt_to_mfn
gnttab[gnt_idx].dest.u.gmfn = virt_to_mfn(
gnttab[gnt_idx].source.u.gmfn = virt_to_mfn(
virt_to_mfn(mtod(pMbuf, vm_offset_t)));
virt_to_mfn(mtod(mbuf, vm_offset_t)));
error = xenbus_grant_ring(dev, virt_to_mfn(rxs),
error = xenbus_grant_ring(dev, virt_to_mfn(txs),
err = xenbus_grant_ring(pdev->xdev, virt_to_mfn(pdev->sh_info));