On Fri, 08 Sep 2017 08:05:38 +1000 Benjamin Herrenschmidt <[email protected]> wrote:
> On Fri, 2017-09-08 at 00:51 +1000, Nicholas Piggin wrote: > > When permissiveness is relaxed, or found to have been relaxed by > > another thread, we flush that address out of the TLB to avoid a > > future fault or micro-fault due to a stale TLB entry. > > > > Currently for processes with TLBs on other CPUs, this flush is always > > done with a global tlbie. Although that could reduce faults on remote > > CPUs, a broadcast operation seems to be wasteful for something that > > can be handled in-core by the remote CPU if it comes to it. > > > > This is not benchmarked yet. It does seem cut some tlbie operations > > from the bus. > > What happens with the nest MMU here ? Good question, I'm not sure. I can't tell from the UM or not if the agent and NMMU must discard cached translations if there is a translation cached but it has a permission fault. It's not clear from that I've read that if it's relying on the host to send back a tlbie. I'll keep digging. Thanks, Nick
