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{
    "id": 80334,
    "url": "https://patches.dpdk.org/api/covers/80334/?format=api",
    "web_url": "https://patches.dpdk.org/project/dpdk/cover/20201012081106.10610-1-ndabilpuram@marvell.com/",
    "project": {
        "id": 1,
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        "name": "DPDK",
        "link_name": "dpdk",
        "list_id": "dev.dpdk.org",
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    "msgid": "<20201012081106.10610-1-ndabilpuram@marvell.com>",
    "list_archive_url": "https://inbox.dpdk.org/dev/20201012081106.10610-1-ndabilpuram@marvell.com",
    "date": "2020-10-12T08:11:04",
    "name": "[0/2] fix issue with partial DMA unmap",
    "submitter": {
        "id": 1202,
        "url": "https://patches.dpdk.org/api/people/1202/?format=api",
        "name": "Nithin Dabilpuram",
        "email": "ndabilpuram@marvell.com"
    },
    "mbox": "https://patches.dpdk.org/project/dpdk/cover/20201012081106.10610-1-ndabilpuram@marvell.com/mbox/",
    "series": [
        {
            "id": 12874,
            "url": "https://patches.dpdk.org/api/series/12874/?format=api",
            "web_url": "https://patches.dpdk.org/project/dpdk/list/?series=12874",
            "date": "2020-10-12T08:11:04",
            "name": "fix issue with partial DMA unmap",
            "version": 1,
            "mbox": "https://patches.dpdk.org/series/12874/mbox/"
        }
    ],
    "comments": "https://patches.dpdk.org/api/covers/80334/comments/",
    "headers": {
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        ],
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        "From": "Nithin Dabilpuram <ndabilpuram@marvell.com>",
        "To": "<anatoly.burakov@intel.com>",
        "CC": "<jerinj@marvell.com>, <dev@dpdk.org>, Nithin Dabilpuram\n <ndabilpuram@marvell.com>",
        "Date": "Mon, 12 Oct 2020 13:41:04 +0530",
        "Message-ID": "<20201012081106.10610-1-ndabilpuram@marvell.com>",
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        "Subject": "[dpdk-dev] [PATCH 0/2] fix issue with partial DMA unmap",
        "X-BeenThere": "dev@dpdk.org",
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    },
    "content": "Partial DMA unmap is not supported by VFIO type1 IOMMU\nin Linux. Though the return value is zero, the returned\nDMA unmap size is not same as expected size.\nSo add test case and fixe to both heap triggered DMA\nmapping and user triggered DMA mapping/unmapping.\n\nRefer vfio_dma_do_unmap() in drivers/vfio/vfio_iommu_type1.c\nSnippet of comment is below.\n\n        /*\n         * vfio-iommu-type1 (v1) - User mappings were coalesced together to\n         * avoid tracking individual mappings.  This means that the granularity\n         * of the original mapping was lost and the user was allowed to attempt\n         * to unmap any range.  Depending on the contiguousness of physical\n         * memory and page sizes supported by the IOMMU, arbitrary unmaps may\n         * or may not have worked.  We only guaranteed unmap granularity\n         * matching the original mapping; even though it was untracked here,\n         * the original mappings are reflected in IOMMU mappings.  This\n         * resulted in a couple unusual behaviors.  First, if a range is not\n         * able to be unmapped, ex. a set of 4k pages that was mapped as a\n         * 2M hugepage into the IOMMU, the unmap ioctl returns success but with\n         * a zero sized unmap.  Also, if an unmap request overlaps the first\n         * address of a hugepage, the IOMMU will unmap the entire hugepage.\n         * This also returns success and the returned unmap size reflects the\n         * actual size unmapped.\n\n         * We attempt to maintain compatibility with this \"v1\" interface, but  \n         * we take control out of the hands of the IOMMU.  Therefore, an unmap \n         * request offset from the beginning of the original mapping will      \n         * return success with zero sized unmap.  And an unmap request covering\n         * the first iova of mapping will unmap the entire range.              \n\nThis behavior can be verified by using first patch and add return check for\ndma_unmap.size != len in vfio_type1_dma_mem_map()\n\nNithin Dabilpuram (2):\n  test: add test case to validate VFIO DMA map/unmap\n  vfio: fix partial DMA unmapping for VFIO type1\n\n app/test/test_memory.c          | 79 +++++++++++++++++++++++++++++++++++++++++\n lib/librte_eal/linux/eal_vfio.c | 34 ++++++++++++++----\n lib/librte_eal/linux/eal_vfio.h |  1 +\n 3 files changed, 108 insertions(+), 6 deletions(-)"
}