e3075e969e
In vhost-switch example, when binding nic to vfio-pci with iommu enabled, dequeue zero copy cannot work in VM2NIC mode due to no iommu dma mapping is setup for guest memory currently. Signed-off-by: Junjie Chen <junjie.j.chen@intel.com> Reviewed-by: Jianfeng Tan <jianfeng.tan@intel.com> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>