[PATCH v6 8/8] iommufd: Add dma_buf_pin()

[Leon Romanovsky <leon@kernel.org>]

From: Leon Romanovsky <leonro@nvidia.com>

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>
---
 drivers/iommu/iommufd/pages.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c
index 76f900fa1687..a5eb2bc4ef48 100644
--- a/drivers/iommu/iommufd/pages.c
+++ b/drivers/iommu/iommufd/pages.c
@@ -1501,16 +1501,22 @@ 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);
@@ -1656,6 +1662,7 @@ 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));

-- 
2.52.0