Commit 8c5f9645 authored Jan 31, 2026 by Leon Romanovsky Committed by Christian König Feb 23, 2026

iommufd: Add dma_buf_pin()



IOMMUFD relies on a private protocol with VFIO, and this always operated
in pinned mode.

Now that VFIO can support pinned importers update IOMMUFD to invoke the
normal dma-buf flow to request pin.

This isn't enough to allow IOMMUFD to work with other exporters, it still
needs a way to get the physical address list which is another series.

IOMMUFD supports the defined revoke semantics. It immediately stops and
fences access to the memory inside it's invalidate_mappings() callback,
and it currently doesn't use scatterlists so doesn't call map/unmap at
all.

It is expected that a future revision can synchronously call unmap from
the move_notify callback as well.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20260131-dmabuf-revoke-v7-8-463d956bd527@nvidia.com

parent 6ffe939b

drivers/iommu/iommufd/pages.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -1502,16 +1502,22 @@ static int iopt_map_dmabuf(struct iommufd_ctx ictx, struct iopt_pages pages,
		mutex_unlock(&pages->mutex);
		}

		rc = sym_vfio_pci_dma_buf_iommufd_map(attach, &pages->dmabuf.phys);
		rc = dma_buf_pin(attach);
		if (rc)
		goto err_detach;

		rc = sym_vfio_pci_dma_buf_iommufd_map(attach, &pages->dmabuf.phys);
		if (rc)
		goto err_unpin;

		dma_resv_unlock(dmabuf->resv);

		/* On success iopt_release_pages() will detach and put the dmabuf. */
		pages->dmabuf.attach = attach;
		return 0;

		err_unpin:
		dma_buf_unpin(attach);
		err_detach:
		dma_resv_unlock(dmabuf->resv);
		dma_buf_detach(dmabuf, attach);
		@@ -1657,6 +1663,7 @@ void iopt_release_pages(struct kref *kref)
		if (iopt_is_dmabuf(pages) && pages->dmabuf.attach) {
		struct dma_buf *dmabuf = pages->dmabuf.attach->dmabuf;

		dma_buf_unpin(pages->dmabuf.attach);
		dma_buf_detach(dmabuf, pages->dmabuf.attach);
		dma_buf_put(dmabuf);
		WARN_ON(!list_empty(&pages->dmabuf.tracker));