I'm also experienced this problem.
Below is my result.
ConnectX-1 QDR HCA firmware 2.9.1000
with Intel vt-D enable on BIOS -> fail!
with intel vt-D disable on BIOS -> success!
ConnectX-2 QDR HCA firmware 2.9.1200, 1000.
with Intel vt-D enable or not -> All success!
ConnectX-1,2 are all the MT26428 but difference
is chipset revision a, b.