Re: [RFC 4/5] vfio: amba: VFIO support for AMBA devices

[Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>]

Hi Antonios,

On Fri, Aug 22, 2014 at 10:01:27AM +0100, Antonios Motakis wrote:
> Add support for discovering AMBA devices with VFIO and handle them
> similarly to Linux platform devices.

[...]

> +static struct amba_id pl330_ids[] = {
> +	{ 0, 0 },
> +};
> +
> +MODULE_DEVICE_TABLE(amba, pl330_ids);
> +
> +static struct amba_driver vfio_amba_driver = {
> +	.probe = vfio_amba_probe,
> +	.remove = vfio_amba_remove,
> +	.id_table = pl330_ids,
> +	.drv = {
> +		.name = "vfio-amba",
> +		.owner = THIS_MODULE,
> +	},
> +};

I don't understand what you're doing with the IDs here. What's the point in
the empty list?

This also raises a larger question about whether or not it's safe to allow
device passthrough of arbitrary platform devices with VFIO. In the absence
of a bus/device standard like PCI, I really think this should be in opt-in
decision, where certain platform drivers can declare that their device can
be safely used with passthrough.

Thoughts?

Will