Re: [PATCH v6 9/9] vfio/pci: Permanently revoke a DMABUF on request

[Jason Gunthorpe]

On Mon, Sep 21, 2026 at 02:08:47PM +0100, Matt Evans wrote:

> Not quite; the priv->revoked flag tracks temporary periods of
> inaccessibility.  An example is VFIO resetting a function; the BAR
> mappings as seen by the CPU and DMABUFs made from the BARs are all made
> inaccessible before the reset, and made accessible again after the
> reset.

>From the importer perspective this is a permanent revoke.

The right way to view this flow is VFIO permanently revokes the DMABUF
FD. Then instead of forcing a new FD to be obtained it replaces the
existing FD with a working one.

>From an importer perspective it sees the revoke happen and then that's
it, the dmabuf never does anything further. The importer has to unmap
and start from scratch, get a FD and map it.

That VFIO re-used the FD to make a new live export isn't visible to
the importer at all.

I think that is where this "temporary revoke" language gets confusing.

Call it "VFIO reuses the FD to create a new live mapping" is clearer
than calling it "temporarily revoke" which sounds too much like move.

Jason