On Fri, Sep 02, 2016 at 02:15:57PM +0800, Peter Xu wrote: > > 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.
The problem is that, IMHO we should be very careful on enabling CM bit. After enabling it, system might get slower (though I haven't tried it yet), or even very slow? So maybe we will only enable it when really needed (e.g., to do device passthrough and build the shadow table). -- peterx
