780bc7903a
virtio_ring currently sends the device (usually a hypervisor) physical addresses of its I/O buffers. This is okay when DMA addresses and physical addresses are the same thing, but this isn't always the case. For example, this never works on Xen guests, and it is likely to fail if a physical "virtio" device ever ends up behind an IOMMU or swiotlb. The immediate use case for me is to enable virtio on Xen guests. For that to work, we need vring to support DMA address translation as well as a corresponding change to virtio_pci or to another driver. Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
18 lines
300 B
C
18 lines
300 B
C
#ifndef _LINUX_DMA_MAPPING_H
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#define _LINUX_DMA_MAPPING_H
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#ifdef CONFIG_HAS_DMA
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# error Virtio userspace code does not support CONFIG_HAS_DMA
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#endif
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#define PCI_DMA_BUS_IS_PHYS 1
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enum dma_data_direction {
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DMA_BIDIRECTIONAL = 0,
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DMA_TO_DEVICE = 1,
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DMA_FROM_DEVICE = 2,
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DMA_NONE = 3,
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};
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#endif
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