RE: [PATCH v10 04/12] iommu: Add attach/detach_dev_pasid iommu interface

[Tian, Kevin]

> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Thursday, August 4, 2022 3:03 AM
> 
> On Wed, Aug 03, 2022 at 09:07:35PM +0800, Baolu Lu wrote:
> > +/**
> > + * iommu_device_claim_pasid_owner() - Set ownership of a pasid on
> device
> > + * @dev: the device.
> > + * @pasid: the pasid of the device.
> > + * @owner: caller specified pointer. Used for exclusive ownership.
> > + *
> > + * Return 0 if it is allowed, otherwise an error.
> > + */
> > +int iommu_device_claim_pasid_owner(struct device *dev, ioasid_t pasid,
> void
> > *owner)
> 
> I don't see a use case for a special "pasid owner"
> 
> PASID is no different from normal DMA. If the calling driver already
> has the proper ownership of the device/group then it is fine for that
> driver to use any kind of IOMMU attachment, RID, PASID, whatever. It
> doesn't matter *how* the attachment is made.
> 

and pasid already has an alloc/free interface which already implies
an ownership model.