From 780bc7903a32edb63be138487fd981694d993610 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Tue, 2 Feb 2016 21:46:36 -0800 Subject: virtio_ring: Support DMA APIs 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 Signed-off-by: Michael S. Tsirkin --- tools/virtio/linux/dma-mapping.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) create mode 100644 tools/virtio/linux/dma-mapping.h (limited to 'tools/virtio') diff --git a/tools/virtio/linux/dma-mapping.h b/tools/virtio/linux/dma-mapping.h new file mode 100644 index 0000000..4f93af8 --- /dev/null +++ b/tools/virtio/linux/dma-mapping.h @@ -0,0 +1,17 @@ +#ifndef _LINUX_DMA_MAPPING_H +#define _LINUX_DMA_MAPPING_H + +#ifdef CONFIG_HAS_DMA +# error Virtio userspace code does not support CONFIG_HAS_DMA +#endif + +#define PCI_DMA_BUS_IS_PHYS 1 + +enum dma_data_direction { + DMA_BIDIRECTIONAL = 0, + DMA_TO_DEVICE = 1, + DMA_FROM_DEVICE = 2, + DMA_NONE = 3, +}; + +#endif -- cgit v1.1