xen/arm,arm64: enable SWIOTLB_XEN
Xen on arm and arm64 needs SWIOTLB_XEN: when running on Xen we need to program the hardware with mfns rather than pfns for dma addresses. Remove SWIOTLB_XEN dependency on X86 and PCI and make XEN select SWIOTLB_XEN on arm and arm64. At the moment always rely on swiotlb-xen, but when Xen starts supporting hardware IOMMUs we'll be able to avoid it conditionally on the presence of an IOMMU on the platform. Implement xen_create_contiguous_region on arm and arm64: for the moment we assume that dom0 has been mapped 1:1 (physical addresses == machine addresses) therefore we don't need to call XENMEM_exchange. Simply return the physical address as dma address. Initialize the xen-swiotlb from xen_early_init (before the native dma_ops are initialized), set xen_dma_ops to &xen_swiotlb_dma_ops. Signed-off-by: Stefano Stabellini <firstname.lastname@example.org> Changes in v8: - assume dom0 is mapped 1:1, no need to call XENMEM_exchange. Changes in v7: - call __set_phys_to_machine_multi from xen_create_contiguous_region and xen_destroy_contiguous_region to update the P2M; - don't call XENMEM_unpin, it has been removed; - call XENMEM_exchange instead of XENMEM_exchange_and_pin; - set nr_exchanged to 0 before calling the hypercall. Changes in v6: - introduce and export xen_dma_ops; - call xen_mm_init from as arch_initcall. Changes in v4: - remove redefinition of DMA_ERROR_CODE; - update the code to use XENMEM_exchange_and_pin and XENMEM_unpin; - add a note about hardware IOMMU in the commit message. Changes in v3: - code style changes; - warn on XENMEM_put_dma_buf failures.
Showing with 86 additions and 3 deletions