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path: root/kernel/dma/direct.h
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2022-07-26dma-direct: support PCI P2PDMA pages in dma-direct map_sgLogan Gunthorpe
Add PCI P2PDMA support for dma_direct_map_sg() so that it can map PCI P2PDMA pages directly without a hack in the callers. This allows for heterogeneous SGLs that contain both P2PDMA and regular pages. A P2PDMA page may have three possible outcomes when being mapped: 1) If the data path between the two devices doesn't go through the root port, then it should be mapped with a PCI bus address 2) If the data path goes through the host bridge, it should be mapped normally, as though it were a CPU physical address 3) It is not possible for the two devices to communicate and thus the mapping operation should fail (and it will return -EREMOTEIO). SGL segments that contain PCI bus addresses are marked with sg_dma_mark_pci_p2pdma() and are ignored when unmapped. P2PDMA mappings are also failed if swiotlb needs to be used on the mapping. Signed-off-by: Logan Gunthorpe <logang@deltatee.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christoph Hellwig <hch@lst.de>
2022-04-18dma-direct: use is_swiotlb_active in dma_direct_map_pageChristoph Hellwig
Use the more specific is_swiotlb_active check instead of checking the global swiotlb_force variable. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2022-04-14dma-direct: avoid redundant memory sync for swiotlbChao Gao
When we looked into FIO performance with swiotlb enabled in VM, we found swiotlb_bounce() is always called one more time than expected for each DMA read request. It turns out that the bounce buffer is copied to original DMA buffer twice after the completion of a DMA request (one is done by in dma_direct_sync_single_for_cpu(), the other by swiotlb_tbl_unmap_single()). But the content in bounce buffer actually doesn't change between the two rounds of copy. So, one round of copy is redundant. Pass DMA_ATTR_SKIP_CPU_SYNC flag to swiotlb_tbl_unmap_single() to skip the memory copy in it. This fix increases FIO 64KB sequential read throughput in a guest with swiotlb=force by 5.6%. Fixes: 55897af63091 ("dma-direct: merge swiotlb_dma_ops into the dma_direct code") Reported-by: Wang Zhaoyang1 <zhaoyang1.wang@intel.com> Reported-by: Gao Liang <liang.gao@intel.com> Signed-off-by: Chao Gao <chao.gao@intel.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
2021-07-13swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncingClaire Chang
Propagate the swiotlb_force into io_tlb_default_mem->force_bounce and use it to determine whether to bounce the data or not. This will be useful later to allow for different pools. Signed-off-by: Claire Chang <tientzu@chromium.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Stefano Stabellini <sstabellini@kernel.org> Tested-by: Will Deacon <will@kernel.org> Acked-by: Stefano Stabellini <sstabellini@kernel.org> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> [v2: Includes Will's fix]
2021-07-13swiotlb: Update is_swiotlb_buffer to add a struct device argumentClaire Chang
Update is_swiotlb_buffer to add a struct device argument. This will be useful later to allow for different pools. Signed-off-by: Claire Chang <tientzu@chromium.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Stefano Stabellini <sstabellini@kernel.org> Tested-by: Will Deacon <will@kernel.org> Acked-by: Stefano Stabellini <sstabellini@kernel.org> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2021-03-17swiotlb: split swiotlb_tbl_sync_singleChristoph Hellwig
Split swiotlb_tbl_sync_single into two separate funtions for the to device and to cpu synchronization. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2021-03-17swiotlb: remove the alloc_size parameter to swiotlb_tbl_unmap_singleChristoph Hellwig
Now that swiotlb remembers the allocation size there is no need to pass it back to swiotlb_tbl_unmap_single. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2020-10-06dma-mapping: move large parts of <linux/dma-direct.h> to kernel/dmaChristoph Hellwig
Most of the dma_direct symbols should only be used by direct.c and mapping.c, so move them to kernel/dma. In fact more of dma-direct.h should eventually move, but that will require more coordination with other subsystems. Signed-off-by: Christoph Hellwig <hch@lst.de>