On Fri, Jan 30, 2026 at 09:43:22AM +0100, Christian König wrote: > On 1/24/26 20:14, Leon Romanovsky wrote: > > From: Leon Romanovsky <[email protected]> > > > > Some exporters need a flow to synchronously revoke access to the DMA-buf > > by importers. Once revoke is completed the importer is not permitted to > > touch the memory otherwise they may get IOMMU faults, AERs, or worse. > > That approach is seriously not going to fly. > > You can use the invalidate_mappings approach to trigger the importer > to give back the mapping, but when the mapping is really given back > is still completely on the importer side.
Yes, and that is what this is all doing, there is the wait for the importer's unmap to happen in the sequence. > In other words you can't do the shot down revoke semantics you are > trying to establish here. All this is doing is saying if dma_buf_attach_revocable() == true then the importer will call unmap within bounded time after dma_buf_invalidate_mappings(). That's it. If the importing driver doesn't want to do that then it should make dma_buf_attach_revocable()=false. VFIO/etc only want to interwork with importers that can do this. Jason
