Re: [PATCH v4 1/2] iommu/sva: Tighten SVA bind API with explicit flags

Jason Gunthorpe
2021-05-13T13:38:51Z

On Thu, May 13, 2021 at 06:00:12AM -0700, Jacob Pan wrote:
> > > If you want to do SVA PASID then it also must come with DMA APIs to
> > > manage the CPU cache coherence that are all NOP's on x86.
> >
> > Yes. And we have plenty of precende where an IOMMU is in "bypass" mode
> > to allow access to all memory and then uses the simple dma-direct case.
> I agree it is better not to expose the entire direct map. But the missing
> piece of using DMA APIs is the PASID. The caller needs the PASID value to
> do work submission once buffer is mapped.

You still haven't explained why the kernel driver should have a PASID at all.

Jason