RE: [PATCH v2 00/10] Add IO page table replacement support

[Tian, Kevin]

> From: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Sent: Friday, February 10, 2023 12:13 AM
> 
> On Thu, Feb 09, 2023 at 02:50:39AM +0000, Tian, Kevin wrote:
> > External email: Use caution opening links or attachments
> >
> >
> > > From: Nicolin Chen <nicolinc@xxxxxxxxxx>
> > > Sent: Wednesday, February 8, 2023 5:18 AM
> > >
> > > QEMU with this feature should have the vIOMMU maintain a cache of the
> > > guest io page table addresses and assign a unique IOAS to each unique
> > > guest page table.
> > >
> >
> > I still didn't see a clear reply why above is required. Please elaborate.
> 
> Hmm..this piece was directly copied from Jason's inputs before I
> sent v1. And I thought he explained in the previous version. I
> can drop it in v3 if that makes you happy.
> 

Jason's reply was:

> I think the guidance is about the change to VFIO uAPI where it is now
> possible to change the domain attached, previously that was not
> possible

I cannot connect it to the above statement. Anyway if you think
that guidance to userspace is necessary please connect it to the
replace semantics to explain the motivation.