[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

 1 static int
 2 vfio_type1_dma_mem_map(int vfio_container_fd, uint64_t vaddr, uint64_t iova,
 3         uint64_t len, int do_map)
 4 {
 5     struct vfio_iommu_type1_dma_map dma_map;
 6     struct vfio_iommu_type1_dma_unmap dma_unmap;
 7     int ret;
 8 
 9     if (do_map != 0) {
10         memset(&dma_map, 0, sizeof(dma_map));
11         dma_map.argsz = sizeof(struct vfio_iommu_type1_dma_map);
12         dma_map.vaddr = vaddr;
13         dma_map.size = len;
14         dma_map.iova = iova;
15         dma_map.flags = VFIO_DMA_MAP_FLAG_READ |
16                 VFIO_DMA_MAP_FLAG_WRITE;
17 
18 //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。
19         ret = ioctl(vfio_container_fd, VFIO_IOMMU_MAP_DMA, &dma_map);
20         if (ret) {
21             /**
22              * In case the mapping was already done EEXIST will be
23              * returned from kernel.
24              */
25             if (errno == EEXIST) {
26                 RTE_LOG(DEBUG, EAL,
27                     " Memory segment is already mapped,"
28                     " skipping");
29             } else {
30                 RTE_LOG(ERR, EAL,
31                     "  cannot set up DMA remapping,"
32                     " error %i (%s)
",
33                     errno, strerror(errno));
34                 return -1;
35             }
36         }
37     } else {
38         memset(&dma_unmap, 0, sizeof(dma_unmap));
39         dma_unmap.argsz = sizeof(struct vfio_iommu_type1_dma_unmap);
40         dma_unmap.size = len;
41         dma_unmap.iova = iova;
42 
43         ret = ioctl(vfio_container_fd, VFIO_IOMMU_UNMAP_DMA,
44                 &dma_unmap);
45         if (ret) {
46             RTE_LOG(ERR, EAL, "  cannot clear DMA remapping, error %i (%s)
",
47                     errno, strerror(errno));
48             return -1;
49         }
50     }
51 
52     return 0;
53 }