RE: [PATCH v2 3/8] iommu/vt-d: Implement device_pasid domain attach ops

Tian, Kevin
2022-03-16T07:41:48Z

> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Tuesday, March 15, 2022 10:33 PM
>
> On Mon, Mar 14, 2022 at 10:07:07PM -0700, Jacob Pan wrote:
> > + /*
> > + * Each domain could have multiple devices attached with shared or
> per
> > + * device PASIDs. At the domain level, we keep track of unique PASIDs
> and
> > + * device user count.
> > + * E.g. If a domain has two devices attached, device A has PASID 0, 1;
> > + * device B has PASID 0, 2. Then the domain would have PASID 0, 1, 2.
> > + */
>
> A 2d array of xarray's seems like a poor data structure for this task.

besides that it also doesn't work when we support per-device PASID allocation
in the future. In that case merging device PASIDs together is conceptually
wrong.

>
> AFACIT this wants to store a list of (device, pasid) tuples, so a
> simple linked list, 1d xarray vector or a red black tree seems more
> appropriate..
>

this tuple can well serve per-device PASID. 😊

Thanks
Kevin