Hi Oliver, On Tue, Jul 26, 2022 at 10:51:21AM -0700, Oliver Upton wrote: > Hi Alex, > > On Mon, Jul 25, 2022 at 11:06:24AM +0100, Alexandru Elisei wrote: > > [...] > > I'm also a bit confused on how we would manage to un-pin memory on the > way out with this. The guest is free to muck with the stage 1 and could > cause the SPU to spew a bunch of stage 2 aborts if it wanted to be > annoying. One way to tackle it would be to only allow a single > root-to-target walk to be pinned by a vCPU at a time. Any time a new > stage 2 abort comes from the SPU, we un-pin the old walk and pin the new > one instead. On the topic of memory unpinning, for a well behaved guest I belive that should be done the next time the buffer is pinned. The buffer can (and should!) be drained when both the buffer and sampling is disabled; unpinning the buffer when profiling becomes disabled would lead to unnecessary stage 2 faults when draining it. That approach also means that KVM wouldn't have to do anything special for SPE stage 2 faults. Thanks, Alex _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
