Re: [PATCH v3 06/14] vfio/type1: Add VFIO_IOMMU_PASID_REQUEST (alloc/free)

[Jacob Pan]

On Thu, 9 Jul 2020 08:27:51 -0600
Alex Williamson <alex.williamson@xxxxxxxxxx> wrote:

> > So I'm wondering can we fall back to prior proposal which only free
> > one PASID for a free request. how about your opinion?  
> 
> Doesn't it still seem like it would be a useful user interface to have
> a mechanism to free all pasids, by calling with exactly [0, MAX_UINT]?
> I'm not sure if there's another use case for this given than the user
> doesn't have strict control of the pasid values they get.  Thanks,

Yes, I agree free all pasids of a guest is a useful interface. Since all
PASIDs under one VM is already tracked by an IOASID set with its XArray,
I don't see a need to track again in VFIO.

Shall we only free one & free all? IMHO, free range isn't that useful
and not really symmetric to PASID allocation in that allocation is one
at a time.

Can we just add a new flag, e.g.  VFIO_IOMMU_FREE_ALL_PASID, and
ignored th range in free?