Re: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and allocation APIs

Jean-Philippe Brucker
2021-03-25T10:28:00Z

On Wed, Mar 24, 2021 at 10:02:46AM -0700, Jacob Pan wrote:
> > And a flag IOMMU_SVA_BIND_SUPERVISOR (not that I plan to implement it in
> > the SMMU, but I think we need to clean the current usage)
> >
> You mean move #define SVM_FLAG_SUPERVISOR_MODE out of Intel code to be a
> generic flag in iommu-sva-lib.h called IOMMU_SVA_BIND_SUPERVISOR?

Yes, though it would need to be in iommu.h since it's used by device
drivers

> > Also wondering about device driver allocating auxiliary domains for their
> > private use, to do iommu_map/unmap on private PASIDs (a clean replacement
> > to super SVA, for example). Would that go through the same path as
> > /dev/ioasid and use the cgroup of current task?
> >
> For the in-kernel private use, I don't think we should restrict based on
> cgroup, since there is no affinity to user processes. I also think the
> PASID allocation should just use kernel API instead of /dev/ioasid. Why
> would user space need to know the actual PASID # for device private domains?
> Maybe I missed your idea?

No that's my bad, I didn't get the role of /dev/ioasid. Let me give the
series a proper read.

Thanks,
Jean