On Mon, Apr 20, 2020 at 10:48:50AM -0700, Jacob Pan wrote: > On Mon, 20 Apr 2020 10:57:27 -0300 > Jason Gunthorpe <jgg@xxxxxxxx> wrote: > > > On Mon, Apr 20, 2020 at 09:42:13AM +0200, Jean-Philippe Brucker wrote: > > > 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. > > > > I've been getting rid of hash tables like this.. Adding it to the > > mm_struct does seem reasonable, I think PASID is a pretty broad > > concept now. > > > Agreed, perhaps Fenghua can consider that in his patchset. It would > help align life cycles as well. > https://lkml.org/lkml/2020/3/30/910> Seems we depend on each other: my patch defines pasid in mm_struct. I can free PASID in your detach() function. Thanks. -Fenghua
