Re: [PATCH v1 5/8] iommu/amd: Use iommu_attach/detach_device()

[Jason Gunthorpe]

On Mon, Feb 14, 2022 at 12:27:05PM +0100, Joerg Roedel wrote:
> On Thu, Jan 06, 2022 at 10:33:45AM -0400, Jason Gunthorpe wrote:
> > But I'm not sure how this can work with multi-device groups - this
> > seems to assigns a domain setup for direct map, so perhaps this only
> > works if all devices are setup for direct map?
> 
> Right, at boot all devices in this group are already setup for using a
> direct map. There are usually two devices in those groups, the GPU
> itself and the sound device for HDMI sound output.

But how does the sound device know that this has been done to it?

eg how do we know the sound device hasn't been bound to VFIO or
something at this point?

Jason