qemu-system-x86_64: "VFIO_MAP_DMA : -28" error when we attache 6 VF's to guest machine

We are trying to attach 6 VF's to the guest machine on 4.1.1 qemu emulator.
We are observing "VFIO_MAP_DMA : -28" error.

We are using w-bits=48 bits while lunching VM.