On 1/18/26 13:08, Leon Romanovsky wrote:
> From: Leon Romanovsky <[email protected]>
>
> 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 <[email protected]>
> ---
> 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;
It's probably better to do that check in vfio_pci_dma_buf_attach.
And BTW the function vfio_pci_dma_buf_move() seems to be broken:
void vfio_pci_dma_buf_move(struct vfio_pci_core_device *vdev, bool revoked)
{
struct vfio_pci_dma_buf *priv;
struct vfio_pci_dma_buf *tmp;
lockdep_assert_held_write(&vdev->memory_lock);
list_for_each_entry_safe(priv, tmp, &vdev->dmabufs, dmabufs_elm) {
if (!get_file_active(&priv->dmabuf->file))
continue;
if (priv->revoked != revoked) {
dma_resv_lock(priv->dmabuf->resv, NULL);
priv->revoked = revoked;
dma_buf_move_notify(priv->dmabuf);
A dma_buf_move_notify() just triggers asynchronous invalidation of the mapping!
You need to use dma_resv_wait() to wait for that to finish.
dma_resv_unlock(priv->dmabuf->resv);
}
fput(priv->dmabuf->file);
}
}
Regards,
Christian.
> +}
> +
> +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,
>
