On Wed, Jan 21, 2026 at 12:01:40PM -0400, Jason Gunthorpe wrote: > On Wed, Jan 21, 2026 at 04:28:17PM +0100, Christian König wrote: > > On 1/21/26 14:31, Jason Gunthorpe wrote: > > > On Wed, Jan 21, 2026 at 10:20:51AM +0100, Christian König wrote: > > >> On 1/20/26 15:07, Leon Romanovsky wrote: > > >>> From: Leon Romanovsky <[email protected]> > > >>> > > >>> 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 <[email protected]> > > >> > > >> Reviewed-by: Christian König <[email protected]> > > >> > > >> Please also keep in mind that the while this wait for all fences for > > >> correctness you also need to keep the mapping valid until > > >> dma_buf_unmap_attachment() was called. > > > > > > Can you elaborate on this more? > > > > > > I think what we want for dma_buf_attach_revocable() is the strong > > > guarentee that the importer stops doing all access to the memory once > > > this sequence is completed and the exporter can rely on it. I don't > > > think this works any other way. > > > > > > This is already true for dynamic move capable importers, right? > > > > Not quite, no. > > :( > > It is kind of shocking to hear these APIs work like this with such a > loose lifetime definition. Leon can you include some of these detail > in the new comments?
If we can clarify what needs to be addressed for v5, I will proceed. At the moment, it's still unclear what is missing in v4. Thanks
