Re: [PATCH v4] bus/pci: fix legacy device IO port map in secondary process

[David Marchand <david.marchand@redhat.com>]

On Mon, Oct 9, 2023 at 5:06 AM Ma, WenwuX <wenwux.ma@intel.com> wrote:
> > From a pci bus API pov, nothing prevents a driver from mixing memory
> > mapped with vfio and ioport resources (iow, calls to
> > rte_pci_map_resource() and rte_pci_ioport_map()).
> > IOW, it may not be the case with the net/virtio driver but, in theory,
> > rte_pci_ioport_map()/pci_vfio_ioport_map() may be called after a
> > rte_pci_map_resource() call.
> >
> > In a similar manner, from the API pov,
> > rte_pci_ioport_map()/pci_vfio_ioport_map() may be called for multiple bars.
> >
> > In summary, nothing in this patch checks that vfio has been configured already
> > and I think we need a refcount to handle those situations.
> >
> We call rte_vfio_setup_device just to get device info, we can call rte_vfio_release_device as soon as pci_vfio_fill_regions is done.
> This avoids reference counting operations, do you think it works?

Afaics, rte_vfio_setup_device should not be called if a call to
rte_pci_map_device for this device was successful (rte_pci_map_device
itself calls rte_vfio_setup_device).
And as a consequence, calling rte_vfio_release_device cannot be done
unconditionnally neither.


-- 
David Marchand