The problem also seems to occur with NVMe's using the Silicon Motion SM2263XT (different from SM2263) controller. In my case the HP EX900 250G.
I'm running version 6.7.0-rc2 and get the same error:
internal error: qemu unexpectedly closed the monitor: 2019-02-07T17:55:09.769688Z qemu-system-x86_64: -device vfio-pci,host=05:00.0,id=hostdev0,bus=pci.3,addr=0x0: vfio 0000:05:00.0: failed to add PCI capability 0x11[0x50]@0xb0: table & pba overlap, or they don't fit in BARs, or don't align
IOMMU group 51:[126f:2263] 05:00.0 Non-Volatile memory controller: Silicon Motion, Inc. Device 2263 (rev 03)
IOMMU group 52:[126f:2263] 06:00.0 Non-Volatile memory controller: Silicon Motion, Inc. Device 2263 (rev 03)
Please add the SM2263XT controller support, Thanks !