RE: [PATCH 04/14] iommufd: Use the iommufd_group to avoid duplicate reserved groups and msi setup

Tian, Kevin
2023-03-03T02:16:29Z

> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Thursday, March 2, 2023 8:55 PM
>
> On Thu, Mar 02, 2023 at 08:06:27AM +0000, Tian, Kevin wrote:
> > > From: Jason Gunthorpe <jgg@nvidia.com>
> > > Sent: Saturday, February 25, 2023 8:28 AM
> > >
> > > These items only needs to be done once per group, not once per device.
> The
> > > once per device was a way to make the device list work. Since we are
> > > abandoning this we can optimize things a bit.
> > >
> >
> > Are we sure that a device hot-plugged into the group won't increase the
> > list of reserved IOVA ranges?
> >
> > Currently iommu_get_group_resv_regions() queries reserved regions per
> > device and then merge them into the specified list.
>
> So, maybe we should export the device API from the core code and use
> it here instead of this group stuff. We don't need the core code to
> merge each device together for us anyhow.
>

Yes, that'd be clearer in this context.