On Thu, Apr 16, 2020 at 05:13:31AM -0700, Christoph Hellwig wrote: > 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. Right, I can see the appeal. I still like having a single mmu notifier per mm because it ensures we allocate a single PASID per mm (as required by x86). I suppose one alternative is to maintain a hashtable of mm->pasid, to avoid iterating over all bonds during allocation. Thanks, Jean
