Re: [PATCH v13 09/13] iommu/sva: Refactoring iommu_sva_bind/unbind_device()

[Baolu Lu]

On 2022/9/9 0:41, Jason Gunthorpe wrote:
> On Thu, Sep 08, 2022 at 05:25:32PM +0100, Jean-Philippe Brucker wrote:
> > On Wed, Sep 07, 2022 at 02:33:11PM -0300, Jason Gunthorpe wrote:
> > > On Wed, Sep 07, 2022 at 10:54:54AM +0100, Jean-Philippe Brucker wrote:
> > >
> > > > Is iommu_domain still going to represent both a device context (whole
> > > > PASID table) and individual address spaces, or are you planning to move
> > > > away from that?  What happens when a driver does:
> > > >
> > > >    d1 = iommu_domain_alloc()
> > > >    iommu_attach_device(d1)
> > > >    d2 = iommu_sva_bind_device()
> > > >    iommu_detach_device(d1)
> > > >
> > > > Does detach
> > > > (a) only disable the non-PASID address space?
> > > > (b) disable everything?
> > > > (c) fail because the driver didn't unbind first?
> > > I think it must be (a), considering how everything is defined and the
> > > needs for vIOMMU emulation.
> > Yes (a) is probably better. The SMMU driver currently implements (c) to
> > ensure that you can't switch device driver without unbinding everything
> > first, and we should keep that check somewhere
> Yes, the owner stuff is a logical place to put that, when ownership
> is all released the PASID table of the group must be empty. Lu?

I agree. The ownership is about the whole device (more precisely,
group), including the RID and PASIDs. When the ownership is converted,
the pasid array must be empty. I will add code in this series to enforce
this. Thanks for pointing out this.

Best regards,
baolu