RE: [PATCH v3 07/17] iommufd: Add IOMMU_RESV_IOVA_RANGES

[Tian, Kevin]

> From: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Sent: Thursday, August 3, 2023 9:23 AM
> 
> On Wed, Aug 02, 2023 at 01:09:28AM +0000, Tian, Kevin wrote:
> > > From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> > > Sent: Wednesday, August 2, 2023 2:23 AM
> > >
> > > On Tue, Aug 01, 2023 at 02:40:44AM +0000, Tian, Kevin wrote:
> > >
> > > > > So, I guess we should leave it like this?
> > > > >
> > > >
> > > > Yes. Along with this discussion (including what you explained for
> sw_msi)
> > > > let's abandon this new cmd and leave it as today.
> > >
> > > You sure? This makes it basically impossible to write a "correct" vmm
> > > that is aware of what the physical memory map must be early on
> > >
> >
> > emmm... I thought it's what you meant by "leave it like this" and the
> > fact that existing VMM's memory layout happens to match the reserved
> > regions. Nobody complains lacking of such a interface for years then
> > we may postpone supporting it until it's really required.
> >
> > btw even if we add this new cmd now, getting the Qemu support to
> > use the aggregated list when creating the guest memory map is not
> > a simple task given currently vfio only passively acts on change
> > notifications in the guest memory layout. It requires a new mechanism
> > to enforce strict order (probe all vfio devices before creating the memory
> > layout) and then injects vfio reserved regions into the layout.
> >
> > Preferably let's not making it a hard dependency for this series.
> 
> Should we drop this and its selftest patch from this series?
> 

Yes. let's drop it.