Re: [PATCH v3 4/4] vfio/type1: Use iommu_aux_at(de)tach_group() APIs

Lu Baolu
2020-07-15T01:04:46Z

Hi Christoph and Jacob,

On 7/15/20 12:29 AM, Jacob Pan wrote:
> On Tue, 14 Jul 2020 09:25:14 +0100
> Christoph Hellwig<hch@infradead.org> wrote:
>
>> On Tue, Jul 14, 2020 at 01:57:03PM +0800, Lu Baolu wrote:
>>> Replace iommu_aux_at(de)tach_device() with
>>> iommu_aux_at(de)tach_group(). It also saves the
>>> IOMMU_DEV_FEAT_AUX-capable physcail device in the vfio_group data
>>> structure so that it could be reused in other places.
>> This removes the last user of iommu_aux_attach_device and
>> iommu_aux_detach_device, which can be removed now.
> it is still used in patch 2/4 inside iommu_aux_attach_group(), right?
>

There is a need to use this interface. For example, an aux-domain is
attached to a subset of a physical device and used in the kernel. In
this usage scenario, there's no need to use vfio/mdev. The device driver
could just allocate an aux-domain and call iommu_aux_attach_device() to
setup the iommu.

Best regards,
baolu