Re: [PATCH v7 7/8] vfio: Permit VFIO to work with pinned importers

[Jason Gunthorpe]

On Wed, Feb 04, 2026 at 05:21:45PM +0100, Christian König wrote:
> On 1/31/26 06:34, Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro@xxxxxxxxxx>
> > 
> > Till now VFIO has rejected pinned importers, largely to avoid being used
> > with the RDMA pinned importer that cannot handle a move_notify() to revoke
> > access.
> > 
> > Using dma_buf_attach_revocable() it can tell the difference between pinned
> > importers that support the flow described in dma_buf_invalidate_mappings()
> > and those that don't.
> > 
> > Thus permit compatible pinned importers.
> > 
> > This is one of two items IOMMUFD requires to remove its private interface
> > to VFIO's dma-buf.
> > 
> > Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> > Reviewed-by: Alex Williamson <alex@xxxxxxxxxxx>
> > Reviewed-by: Christian König <christian.koenig@xxxxxxx>
> > Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx>
> > ---
> >  drivers/vfio/pci/vfio_pci_dmabuf.c | 15 +++------------
> >  1 file changed, 3 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c
> > index 78d47e260f34..a5fb80e068ee 100644
> > --- a/drivers/vfio/pci/vfio_pci_dmabuf.c
> > +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c
> > @@ -22,16 +22,6 @@ struct vfio_pci_dma_buf {
> >  	u8 revoked : 1;
> >  };
> >  
> > -static int vfio_pci_dma_buf_pin(struct dma_buf_attachment *attachment)
> > -{
> > -	return -EOPNOTSUPP;
> > -}
> > -
> > -static void vfio_pci_dma_buf_unpin(struct dma_buf_attachment *attachment)
> > -{
> > -	/* Do nothing */
> > -}
> > -
> 
> This chunk here doesn't want to apply to drm-misc-next, my educated
> guess is that the patch adding those lines is missing in that tree.

Yes. It looks like Alex took it to his next tree:

commit 61ceaf236115f20f4fdd7cf60f883ada1063349a
Author: Leon Romanovsky <leon@xxxxxxxxxx>
Date:   Wed Jan 21 17:45:02 2026 +0200

    vfio: Prevent from pinned DMABUF importers to attach to VFIO DMABUF
    
    Some pinned importers, such as non-ODP RDMA ones, cannot invalidate their
    mappings and therefore must be prevented from attaching to this exporter.
    
    Fixes: 5d74781ebc86 ("vfio/pci: Add dma-buf export support for MMIO regions")
    Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx>
    Reviewed-by: Pranjal Shrivastava <praan@xxxxxxxxxx>
    Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20260121-vfio-add-pin-v1-1-4e04916b17f1@xxxxxxxxxx
    Signed-off-by: Alex Williamson <alex@xxxxxxxxxxx>

The very best thing would be to pull
61ceaf236115f20f4fdd7cf60f883ada1063349a which is cleanly based on
v6.19-rc6 ?

> How should we handle that? Patches 1-3 have already been pushed to
> drm-misc-next and I would rather like to push patches 4-6 through
> that branch as well.

Or we get Alex to take a branch from you for the first 3 and push it?

Jason