[转]vfio相关

转自 

https://www.kernel.org/doc/Documentation/vfio.txt

introduction to vfio https://insujang.github.io/2017-04-27/introduction-to-vfio/

https://luohao-brian.gitbooks.io/interrupt-virtualization/vfio-she-bei-zhi-tong-jian-jie.html

vfio直通设备简介 https://luohao-brian.gitbooks.io/interrupt-virtualization/vfio-she-bei-zhi-tong-jian-jie.html

 vfio中实现的关键点 https://kernelgo.org/vfio-insight.html

• IOMMU和VFIO  http://element-ui.cn/news/show-44900.aspx

vfio文件描述符在/dev/vfio 下

ls -all /dev/vfio
total 0
drwxr-xr-x  2 root  root       80 Feb 25 22:08 .
drwxr-xr-x 18 root  root     4360 Feb 25 22:08 ..
crw-------  1 linux root 237,   0 Feb 25 22:08 2
crw-rw-rw-  1 root  root  10, 196 Jan 13 10:09 vfio

vfio-pci device driver

看dpdk里面怎么用vfio：

vfio_type1_dma_map

static int
vfio_type1_dma_mem_map(int vfio_container_fd, uint64_t vaddr, uint64_t iova,
        uint64_t len, int do_map)
{
    struct vfio_iommu_type1_dma_map dma_map;
    struct vfio_iommu_type1_dma_unmap dma_unmap;
    int ret;

    if (do_map != 0) {
        memset(&dma_map, 0, sizeof(dma_map));
        dma_map.argsz = sizeof(struct vfio_iommu_type1_dma_map);
        dma_map.vaddr = vaddr;
        dma_map.size = len;
        dma_map.iova = iova;
        dma_map.flags = VFIO_DMA_MAP_FLAG_READ |
                VFIO_DMA_MAP_FLAG_WRITE;

//VFIO_IOMMU_MAP_DMA这个命令就是将iova通过IOMMU映射到vaddr对应的物理地址上去。
        ret = ioctl(vfio_container_fd, VFIO_IOMMU_MAP_DMA, &dma_map);
        if (ret) {
            /**
             * In case the mapping was already done EEXIST will be
             * returned from kernel.
             */
            if (errno == EEXIST) {
                RTE_LOG(DEBUG, EAL,
                    " Memory segment is already mapped,"
                    " skipping");
            } else {
                RTE_LOG(ERR, EAL,
                    "  cannot set up DMA remapping,"
                    " error %i (%s)
",
                    errno, strerror(errno));
                return -1;
            }
        }
    } else {
        memset(&dma_unmap, 0, sizeof(dma_unmap));
        dma_unmap.argsz = sizeof(struct vfio_iommu_type1_dma_unmap);
        dma_unmap.size = len;
        dma_unmap.iova = iova;

        ret = ioctl(vfio_container_fd, VFIO_IOMMU_UNMAP_DMA,
                &dma_unmap);
        if (ret) {
            RTE_LOG(ERR, EAL, "  cannot clear DMA remapping, error %i (%s)
",
                    errno, strerror(errno));
            return -1;
        }
    }

    return 0;
}