Re: [Qemu-devel] [PATCH 01/13] driver core: Add iommu_group tracking to struct device

[Greg KH]

On Fri, May 11, 2012 at 04:55:35PM -0600, Alex Williamson wrote:
> IOMMU groups allow IOMMU drivers to represent DMA visibility
> and isolation of devices.  Multiple devices may be grouped
> together for the purposes of DMA.  Placing a pointer on
> struct device enable easy access for things like streaming
> DMA programming and drivers like VFIO.
> 
> Signed-off-by: Alex Williamson <address@hidden>

Can't you get this today from the iommu_ops pointer that is on the bus
that the device is associated with?  Or can devices on a bus have
different iommu_group pointers?

thanks,

greg k-h