On Tue, 19 May 2020 12:24:13 +0530
Kirti Wankhede <kwankhede@xxxxxxxxxx> wrote:
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.
Signed-off-by: Kirti Wankhede <kwankhede@xxxxxxxxxx>
Reviewed-by: Neo Jia <cjia@xxxxxxxxxx>
---
drivers/vfio/vfio_iommu_type1.c | 62 +++++++++++++++++++++++++++++++++--------
include/uapi/linux/vfio.h | 10 +++++++
2 files changed, 61 insertions(+), 11 deletions(-)
(...)
@@ -1085,6 +1093,7 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
ret = -EINVAL;
goto unlock;
}
+
Nit: unrelated whitespace change.
dma = vfio_find_dma(iommu, unmap->iova + unmap->size - 1, 0);
if (dma && dma->iova + dma->size != unmap->iova + unmap->size) {
ret = -EINVAL;
(...)
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 4850c1fef1f8..a1dd2150971e 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -1048,12 +1048,22 @@ struct vfio_bitmap {
* field. No guarantee is made to the user that arbitrary unmaps of iova
* or size different from those used in the original mapping call will
* succeed.
+ * VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP should be set to get dirty bitmap
s/dirty bitmap/the dirty bitmap/
+ * before unmapping IO virtual addresses. When this flag is set, user must
s/user/the user/
+ * provide data[] as structure vfio_bitmap. User must allocate memory to get
"provide a struct vfio_bitmap in data[]" ?
+ * bitmap, zero the bitmap memory and must set size of allocated memory in
+ * vfio_bitmap.size field.
"The user must provide zero-allocated memory via vfio_bitmap.data and
its size in the vfio_bitmap.size field." ?
A bit in bitmap represents one page of user provided
s/bitmap/the bitmap/
+ * page size in 'pgsize', consecutively starting from iova offset. Bit set
s/Bit set/A set bit/
+ * indicates page at that offset from iova is dirty. Bitmap of pages in the
s/indicates page/indicates that the page/
+ * range of unmapped size is returned in vfio_bitmap.data
"A bitmap of the pages in the range of the unmapped size is returned in
the user-provided vfio_bitmap.data." ?
*/
struct vfio_iommu_type1_dma_unmap {
__u32 argsz;
__u32 flags;
+#define VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP (1 << 0)
__u64 iova; /* IO virtual address */
__u64 size; /* Size of mapping (bytes) */
+ __u8 data[];
};
#define VFIO_IOMMU_UNMAP_DMA _IO(VFIO_TYPE, VFIO_BASE + 14)
With the nits addressed,
