Virtio NIC speed is 1Gb when host is 10Gb

My hosts all have 10Gbe network connections, but when i create a vm with a virtio nic, the speed is reported in the rhevm and in the guest os (windows server 2008r2) as a 1Gb nic.

Is there a way to present a 10Gb nic to a windows guest? If not - why not?