On Thu, Mar 12, 2020 at 10:26 PM Richard Henderson <richard.hender...@linaro.org> wrote: > > On 3/12/20 3:10 PM, Alistair Francis wrote: > >> I still think this must be a guest (or nested guest) bug related to > >> clearing > >> PTE bits and failing to flush the TLB properly. > > > > It think so as well now. I have changed the Linux guest and Hypervisor > > to be very aggressive with flushing but still can't get guest user > > space working. I'll keep digging and see if I can figure out what's > > going on. > > > >> > >> I don't see how it could be a qemu tlb flushing bug. The only primitive, > >> sfence.vma, is quite heavy-handed and explicitly local to the thread. > > > > Yes, both sfence and hfence flush all TLBs, so that doesn't seem to be > > the problem. > > Here's an idea: change the tlb_flush() calls to tlb_flush_all_cpus_synced(). > > If that works, it suggests a guest interprocessor interrupt bug in the tlb > shoot-down.
No change. I'll keep looking. Alistair > > > r~
