On Fri, 15 Jan 2021 17:26:42 +0800
Keqian Zhu <zhukeqian1@xxxxxxxxxx> wrote:
> If a group with non-pinned-page dirty scope is detached with dirty
> logging enabled, we should fully populate the dirty bitmaps at the
> time it's removed since we don't know the extent of its previous DMA,
> nor will the group be present to trigger the full bitmap when the user
> retrieves the dirty bitmap.
>
> Fixes: d6a4c185660c ("vfio iommu: Implementation of ioctl for dirty pages tracking")
> Suggested-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> Signed-off-by: Keqian Zhu <zhukeqian1@xxxxxxxxxx>
> ---
> drivers/vfio/vfio_iommu_type1.c | 18 +++++++++++++++++-
> 1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 0b4dedaa9128..4e82b9a3440f 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -236,6 +236,19 @@ static void vfio_dma_populate_bitmap(struct vfio_dma *dma, size_t pgsize)
> }
> }
>
> +static void vfio_iommu_populate_bitmap_full(struct vfio_iommu *iommu)
> +{
> + struct rb_node *n;
> + unsigned long pgshift = __ffs(iommu->pgsize_bitmap);
> +
> + for (n = rb_first(&iommu->dma_list); n; n = rb_next(n)) {
> + struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node);
> +
> + if (dma->iommu_mapped)
> + bitmap_set(dma->bitmap, 0, dma->size >> pgshift);
> + }
> +}
> +
> static int vfio_dma_bitmap_alloc_all(struct vfio_iommu *iommu, size_t pgsize)
> {
> struct rb_node *n;
> @@ -2415,8 +2428,11 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
> * Removal of a group without dirty tracking may allow the iommu scope
> * to be promoted.
> */
> - if (update_dirty_scope)
> + if (update_dirty_scope) {
> update_pinned_page_dirty_scope(iommu);
> + if (iommu->dirty_page_tracking)
> + vfio_iommu_populate_bitmap_full(iommu);
> + }
> mutex_unlock(&iommu->lock);
> }
>
This doesn't do the right thing. This marks the bitmap dirty if:
* The detached group dirty scope was not limited to pinned pages
AND
* Dirty tracking is enabled
AND
* The vfio_dma is *currently* (ie. after the detach) iommu_mapped
We need to mark the bitmap dirty based on whether the vfio_dma *was*
iommu_mapped by the group that is now detached. Thanks,
Alex
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