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With some devices physical addresses are different than dma addresses. To be able to deal with these cases, we need to call phys_to_dma on physical addresses (including machine addresses in Xen terminology) before returning them from xen_swiotlb_alloc_coherent and xen_swiotlb_map_page. We also need to convert dma addresses back to physical addresses using dma_to_phys in xen_swiotlb_free_coherent and xen_swiotlb_unmap_page if we want to do any operations on them. Call dma_to_phys in is_xen_swiotlb_buffer. Introduce xen_phys_to_dma and call phys_to_dma in its implementation. Introduce xen_dma_to_phys and call dma_to_phys in its implementation. Call xen_phys_to_dma/xen_dma_to_phys instead of xen_phys_to_bus/xen_bus_to_phys through swiotlb-xen.c. Everything is taken care of by these changes except for xen_swiotlb_alloc_coherent and xen_swiotlb_free_coherent, which need a few explicit phys_to_dma/dma_to_phys calls. Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com> Tested-by: Corey Minyard <cminyard@mvista.com> Tested-by: Roman Shaposhnik <roman@zededa.com> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20200710223427.6897-9-sstabellini@kernel.org Signed-off-by: Juergen Gross <jgross@suse.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.