Re: [PATCH v5 04/14] driver core: platform: Add driver dma ownership management

[Jason Gunthorpe]

On Mon, Feb 14, 2022 at 10:59:50AM +0100, Greg Kroah-Hartman wrote:

> > +	if (ret && !drv->no_kernel_api_dma)
> > +		iommu_device_unuse_dma_api(dev);
> 
> So you are now going to call this for every platform driver _unless_
> they set this flag?

Yes, it is necessary because VFIO supports platform devices as well
and needs to ensure security. Conflicting kernel driver attachements
must be blocked, just like for PCI.

Jason