user/sven/linux.git/kernel/dma/direct.h, branch v6.1.110

dma-direct: support PCI P2PDMA pages in dma-direct map_sg

2022-07-26T11:27:47Z

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 Reviewed-by: Christoph Hellwig Signed-off-by: Christoph Hellwig

dma-direct: use is_swiotlb_active in dma_direct_map_page

2022-04-18T05:21:08Z

Use the more specific is_swiotlb_active check instead of checking the global swiotlb_force variable. Signed-off-by: Christoph Hellwig Reviewed-by: Anshuman Khandual Reviewed-by: Konrad Rzeszutek Wilk Tested-by: Boris Ostrovsky

dma-direct: avoid redundant memory sync for swiotlb

2022-04-14T04:30:39Z

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 Reported-by: Gao Liang Signed-off-by: Chao Gao Reviewed-by: Kevin Tian Signed-off-by: Christoph Hellwig

swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncing

2021-07-14T00:04:43Z

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 Reviewed-by: Christoph Hellwig Tested-by: Stefano Stabellini Tested-by: Will Deacon Acked-by: Stefano Stabellini Signed-off-by: Konrad Rzeszutek Wilk [v2: Includes Will's fix]

swiotlb: Update is_swiotlb_buffer to add a struct device argument

2021-07-14T00:04:38Z

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 Reviewed-by: Christoph Hellwig Tested-by: Stefano Stabellini Tested-by: Will Deacon Acked-by: Stefano Stabellini Signed-off-by: Konrad Rzeszutek Wilk

swiotlb: split swiotlb_tbl_sync_single

2021-03-17T00:32:01Z

Split swiotlb_tbl_sync_single into two separate funtions for the to device and to cpu synchronization. Signed-off-by: Christoph Hellwig Signed-off-by: Konrad Rzeszutek Wilk

swiotlb: remove the alloc_size parameter to swiotlb_tbl_unmap_single

2021-03-17T00:21:53Z

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 Signed-off-by: Konrad Rzeszutek Wilk

dma-mapping: move large parts of to kernel/dma

2020-10-06T05:07:06Z

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