DMA mapped pages, including those pinned by mdev vendor drivers, might get unpinned and unmapped while migration is active and device is still running. For example, in pre-copy phase while guest driver could access those pages, host device or vendor driver can dirty these mapped pages. Such pages should be marked dirty so as to maintain memory consistency for a user making use of dirty page tracking. To get bitmap during unmap, user should allocate memory for bitmap, set it all zeros, set size of allocated memory, set page size to be considered for bitmap and set flag VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP.
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| @@ -1048,12 +1048,23 @@ struct vfio_bitmap { · 1047 unmodified lines | |||
| 1048 | * field. No guarantee is made to the user that arbitrary unmaps of iova | 1048 | * field. No guarantee is made to the user that arbitrary unmaps of iova |
| 1049 | * or size different from those used in the original mapping call will | 1049 | * or size different from those used in the original mapping call will |
| 1050 | * succeed. | 1050 | * succeed. |
| 1051 | * VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP should be set to get the dirty bitmap | ||
| 1052 | * before unmapping IO virtual addresses. When this flag is set, the user must | ||
| 1053 | * provide a struct vfio_bitmap in data[]. User must provide zero-allocated | ||
| 1054 | * memory via vfio_bitmap.data and its size in the vfio_bitmap.size field. | ||
| 1055 | * A bit in the bitmap represents one page, of user provided page size in | ||
| 1056 | * vfio_bitmap.pgsize field, consecutively starting from iova offset. Bit set | ||
| 1057 | * indicates that the page at that offset from iova is dirty. A Bitmap of the | ||
| 1058 | * pages in the range of unmapped size is returned in the user-provided | ||
| 1059 | * vfio_bitmap.data. | ||
| 1051 | */ | 1060 | */ |
| 1052 | struct vfio_iommu_type1_dma_unmap { | 1061 | struct vfio_iommu_type1_dma_unmap { |
| 1053 | __u32 argsz; | 1062 | __u32 argsz; |
| 1054 | __u32 flags; | 1063 | __u32 flags; |
| 1064 | #define VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP (1 << 0) | ||
| 1055 | __u64 iova; /* IO virtual address */ | 1065 | __u64 iova; /* IO virtual address */ |
| 1056 | __u64 size; /* Size of mapping (bytes) */ | 1066 | __u64 size; /* Size of mapping (bytes) */ |
| 1067 | __u8 data[]; | ||
| 1057 | }; | 1068 | }; |
| 1058 | 1069 | ||
| 1059 | #define VFIO_IOMMU_UNMAP_DMA _IO(VFIO_TYPE, VFIO_BASE + 14) | 1070 | #define VFIO_IOMMU_UNMAP_DMA _IO(VFIO_TYPE, VFIO_BASE + 14) |