> From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> > Sent: Wednesday, July 15, 2020 9:00 AM > > 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@xxxxxxxxxxxxx> 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. > and here is one example usage for adding per-instance pagetables for drm/msm: https://lore.kernel.org/lkml/20200626200414.14382-5-jcrouse@xxxxxxxxxxxxxx/ Thanks Kevin
