[PATCH 1/2] arm/xen: Introduce need_xen_dma_ops and use it in get_dma_ops

If Xen programs the IOMMU to protect a device, it can safely use it's own DMA ops. Some devices may use DMA but are not protected by an IOMMU. A such device still need to use xen-swiotlb. This patch introduces need_xen_dma_ops which will check if a device needs to use xen DMA ops. For now, it's

[PATCH 1/2] arm/xen: Introduce need_xen_dma_ops and use it in get_dma_ops

If Xen programs the IOMMU to protect a device, it can safely use it's own DMA ops. Some devices may use DMA but are not protected by an IOMMU. A such device still need to use xen-swiotlb. This patch introduces need_xen_dma_ops which will check if a device needs to use xen DMA ops. For now, it's