On Fri, Sep 02, 2016 at 04:10:14PM +1000, David Gibson wrote: > On Fri, 2 Sep 2016 13:37:33 +0800 > Peter Xu <pet...@redhat.com> wrote: > > > On Fri, Sep 02, 2016 at 02:15:04PM +1000, David Gibson wrote: > > > What!? I see no reason you need a different notifier, just fix the > > > implementation of the current one. As a bonus this will also give you > > > working VFIO passthrough with vIOMMU on x86, something which should > > > work already, but doesn't. > > > > Hi, David, > > > > Do you mean that we can enhance the interface to suite the two needs? > > E.g., adding a "IOTLB notification type" definition: > > > > - "full": for those who is listening on all mapping changes including > > additions (VFIO use case) > > > > - "cache_only": for those who only cares about cache invalidations > > (device IOTLB, aka, vhost use case) > > > > We can: > > > > - add notify type when we register the notifiers (e.g., when VFIO > > registers IOMMU notifier, it should specify the type as "full", so > > it won't receive notification if it's device IOTLB invalidations). > > > > - pass this type when trigger the notification, so for each IOMMU > > notify handler, it can selectively disgard the notification. > > > > Not sure whether above makes sense. > > No, implement the full notifier, and a listener which only wants the > invalidates can just ignore callbacks which add new mappings. > > As I said, you'll need this to get VFIO working with vIOMMU which > someone is bound to want soon enough anyway.
But for vhost cases, we do not need CM bit enabled. That might be the difference? I think we need to have vhost working even without CM bit. Device IOTLB should be able to achieve that. -- peterx
