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This implements an MMU-based software IOTLB to support mapping kernel dma buffer into userspace dynamically. The basic idea behind it is treating MMU (VA->PA) as IOMMU (IOVA->PA). The software IOTLB will set up MMU mapping instead of IOMMU mapping for the DMA transfer so that the userspace process is able to use its virtual address to access the dma buffer in kernel. To avoid security issue, a bounce-buffering mechanism is introduced to prevent userspace accessing the original buffer directly which may contain other kernel data. During the mapping, unmapping, the software IOTLB will copy the data from the original buffer to the bounce buffer and back, depending on the direction of the transfer. And the bounce-buffer addresses will be mapped into the user address space instead of the original one. Signed-off-by: Xie Yongji <xieyongji@bytedance.com> Acked-by: Jason Wang <jasowang@redhat.com> Link: https://lore.kernel.org/r/20210831103634.33-12-xieyongji@bytedance.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> |
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| .. | ||
| ifcvf | ||
| mlx5 | ||
| vdpa_sim | ||
| vdpa_user | ||
| virtio_pci | ||
| Kconfig | ||
| Makefile | ||
| vdpa.c | ||