infiniband under windows server guest on XenServer 6.2

I'm trying to get infiniband to work under my Windows Server Guest OS under XenServer 6.2.

I installed latest MLNX_OFED in dom0 according to this instruction (http://community.mellanox.com/docs/DOC-1317) and I have several VF there. I attach on of the VF device to my guest OS:

xe vm-param-set other-config:pci=0/0000:84.00.1 uuid=...

Guest OS sees the device but fails to load the driver.

I've tried it with both Win Server 2008 R2 + WinOf v4.40 and Win Server 2012 R2 + WinOf v4.55

Should I do anything special to get it to work?

May be there are some special flags I should pass to the windows installer? I checked the available options but none seem to be relevant.