Re: [PATCH 2/2] iommu/sva: Remove mm parameter from SVA bind API

Jason Gunthorpe
2021-04-15T11:59:49Z

On Thu, Apr 15, 2021 at 01:33:24PM +0800, Lu Baolu wrote:
> Hi Jason,
>
> On 4/14/21 7:26 PM, Jason Gunthorpe wrote:
> > On Wed, Apr 14, 2021 at 02:22:09PM +0800, Lu Baolu wrote:
> >
> > > I still worry about supervisor pasid allocation.
> > >
> > > If we use iommu_sva_alloc_pasid() to allocate a supervisor pasid, which
> > > mm should the pasid be set? I've ever thought about passing &init_mm to
> > > iommu_sva_alloc_pasid(). But if you add "mm != current->mm", this seems
> > > not to work. Or do you prefer a separated interface for supervisor pasid
> > > allocation/free?
> >
> > Without a mm_struct it is not SVA, so don't use SVA APIs for whatever
> > a 'supervisor pasid' is
>
> The supervisor PASID has its mm_struct. The only difference is that the
> device will set priv=1 in its DMA transactions with the PASID.

Soemthing like init_mm should not be used with 'SVA'

Jason