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Date:   Sun, 1 Oct 2023 23:30:12 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Kelly Devilliv <kelly.devilliv@outlook.com>
Cc:     Christian =?iso-8859-1?Q?K=F6nig?= <christian.koenig@amd.com>,
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        "iommu@lists.linux.dev" <iommu@lists.linux.dev>,
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Subject: Re: dma_map_resource() has a bad performance in pcie peer to peer
 transactions when iommu enabled in Linux
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FYI, dma_map_resources must never be used for PCIe P2P mappings, you
absolutely must use dma_map_sg as only that handles all the corner cases
correctly.

And we need to figure out a way to put a check into dma_map_resources
so that people stop abusing it.