[PATCH v2 4/4] vfio: Add pinned interface to perform revoke semantics

[Leon Romanovsky <leon@kernel.org>]

From: Leon Romanovsky <leonro@nvidia.com>

DMABUF ->pin() interface is called when the DMABUF importer perform
its DMA mapping, so let's use this opportunity to check if DMABUF
exporter revoked its buffer or not.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/vfio/pci/vfio_pci_dmabuf.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c
index d4d0f7d08c53..af9c315ddf71 100644
--- a/drivers/vfio/pci/vfio_pci_dmabuf.c
+++ b/drivers/vfio/pci/vfio_pci_dmabuf.c
@@ -20,6 +20,20 @@ struct vfio_pci_dma_buf {
 	u8 revoked : 1;
 };
 
+static int vfio_pci_dma_buf_pin(struct dma_buf_attachment *attachment)
+{
+	struct vfio_pci_dma_buf *priv = attachment->dmabuf->priv;
+
+	dma_resv_assert_held(priv->dmabuf->resv);
+
+	return dma_buf_attachment_is_revoke(attachment) ? 0 : -EOPNOTSUPP;
+}
+
+static void vfio_pci_dma_buf_unpin(struct dma_buf_attachment *attachment)
+{
+	/* Do nothing */
+}
+
 static int vfio_pci_dma_buf_attach(struct dma_buf *dmabuf,
 				   struct dma_buf_attachment *attachment)
 {
@@ -76,6 +90,8 @@ static void vfio_pci_dma_buf_release(struct dma_buf *dmabuf)
 }
 
 static const struct dma_buf_ops vfio_pci_dmabuf_ops = {
+	.pin = vfio_pci_dma_buf_pin,
+	.unpin = vfio_pci_dma_buf_unpin,
 	.attach = vfio_pci_dma_buf_attach,
 	.map_dma_buf = vfio_pci_dma_buf_map,
 	.unmap_dma_buf = vfio_pci_dma_buf_unmap,

-- 
2.52.0