Re: [PATCH v5 02/25] iommu/sva: Manage process address spaces

[Christoph Hellwig <hch@infradead.org>]

On Thu, Apr 16, 2020 at 10:54:02AM +0200, Jean-Philippe Brucker wrote:
> On Thu, Apr 16, 2020 at 12:28:52AM -0700, Christoph Hellwig wrote:
> > > +	rcu_read_lock();
> > > +	hlist_for_each_entry_rcu(bond, &io_mm->devices, mm_node)
> > > +		io_mm->ops->invalidate(bond->sva.dev, io_mm->pasid, io_mm->ctx,
> > > +				       start, end - start);
> > > +	rcu_read_unlock();
> > > +}
> > 
> > What is the reason that the devices don't register their own notifiers?
> > This kinds of multiplexing is always rather messy, and you do it for
> > all the methods.
> 
> This sends TLB and ATC invalidations through the IOMMU, it doesn't go
> through device drivers

I don't think we mean the same thing, probably because of my rather
imprecise use of the word device.

What I mean is that the mmu_notifier should not be embedded into the
io_mm structure (whch btw, seems to have a way to generic name, just
like all other io_* prefixed names), but instead into the
iommu_bond structure.  That avoid the whole multiplexing layer.