On 1/20/26 21:44, Matthew Brost wrote:
On Tue, Jan 20, 2026 at 04:07:06PM +0200, Leon Romanovsky wrote:
From: Leon Romanovsky leonro@nvidia.com
dma-buf invalidation is performed asynchronously by hardware, so VFIO must wait until all affected objects have been fully invalidated.
Fixes: 5d74781ebc86 ("vfio/pci: Add dma-buf export support for MMIO regions") Signed-off-by: Leon Romanovsky leonro@nvidia.com
drivers/vfio/pci/vfio_pci_dmabuf.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c index d4d0f7d08c53..33bc6a1909dd 100644 --- a/drivers/vfio/pci/vfio_pci_dmabuf.c +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c @@ -321,6 +321,9 @@ void vfio_pci_dma_buf_move(struct vfio_pci_core_device *vdev, bool revoked) dma_resv_lock(priv->dmabuf->resv, NULL); priv->revoked = revoked; dma_buf_move_notify(priv->dmabuf);
dma_resv_wait_timeout(priv->dmabuf->resv,DMA_RESV_USAGE_KERNEL, false,MAX_SCHEDULE_TIMEOUT);Should we explicitly call out in the dma_buf_move_notify() / invalidate_mappings kernel-doc that KERNEL slots are the mechanism for communicating asynchronous dma_buf_move_notify / invalidate_mappings events via fences?
Oh, I missed that! And no that is not correct.
This should be DMA_RESV_USAGE_BOOKKEEP so that we wait for everything.
Regards, Christian.
Yes, this is probably implied, but it wouldn’t hurt to state this explicitly as part of the cross-driver contract.
Here is what we have now:
* - Dynamic importers should set fences for any access that they can't * disable immediately from their &dma_buf_attach_ops.invalidate_mappings * callback.Matt
dma_resv_unlock(priv->dmabuf->resv); } fput(priv->dmabuf->file);@@ -342,6 +345,8 @@ void vfio_pci_dma_buf_cleanup(struct vfio_pci_core_device *vdev) priv->vdev = NULL; priv->revoked = true; dma_buf_move_notify(priv->dmabuf);
dma_resv_wait_timeout(priv->dmabuf->resv, DMA_RESV_USAGE_KERNEL,false, MAX_SCHEDULE_TIMEOUT);-- 2.52.0