Re: [RFC PATCH 0/5] vfio/pci: Support ZONE_DEVICE-backed P2P Registration

[Pranjal Shrivastava]

On Thu, Jun 11, 2026 at 02:40:17PM +0000, Pranjal Shrivastava wrote:
> On Wed, Jun 10, 2026 at 01:28:48PM -0300, Jason Gunthorpe wrote:
> > On Wed, Jun 10, 2026 at 03:18:48PM +0000, Pranjal Shrivastava wrote:
> > 

[...]
 
> > > An alternative implementation has been explored which integrates with the
> > > ongoing VFIO DMABUF-mmap refactor [1]. In that approach, rather than
> > > registering a BAR as a system-wide P2P provider, VFIO optionally
> > > allocates ZONE_DEVICE pages only for specifically exported DMABUFs via a
> > > new VFIO_DMA_BUF_FLAG_ALLOC_STRUCT_PAGES flag.
> > 
> > That's probably more sensible but you can't have a DMABUF mmap
> > actually install non-special memory. The native vfio mmap still can,
> > but not mmap on the dmabuf fd. That's still workable, just keep in
> > mind.
> 
> Ack. I guess, we could have a separate mmap path in case of BARs that are
> struct page backed which doesn't go through the dmabuf exporter.
> 
> That said, we don't mind moving away from the old API if VFIO mmap can
> support this, we don't mind open-coding with devmem_remap_pages.

Minor correction, I meant: devm_memremap_pages 

Thanks,
Praan