On 20/12/18 13:50, Robert Hoo wrote: > On Thu, 2018-12-20 at 13:38 +0100, Paolo Bonzini wrote: >> On 20/12/18 01:18, Robert Hoo wrote: >>> I think the sooner, the better. Take the time window that Icelake >>> CPU >>> model has just shipped with QEMU 3.1.0 and is not publicly/widely >>> used >>> yet. >> >> We should still leave it in the 3.1 machine types. I've just sent a >> patch to do the same with MPX. >> > I took a look your patch of "Disable MPX support on named CPU models". > Seems you do the same as I do to PCONFIG. So you agree with my above > patch?:-) > > I won't object that keep it in 3.1 machine type as you do to MPX.
Sorry Robert, I changed my mind. If no hypervisor exists that enables PCONFIG for guests (using the PCONFIG_ENABLE processor control), effectively no one can ever have used it. We should disable it in all machine types and Cc qemu-stable. In fact, the same is true for INTEL_PT, which is not supported by any released kernel version and, even is going to be available only with a module parameter when it will be. This is not the same as MPX, which did work even though nobody was probably using it. So this series is correct and I will follow up with one for INTEL_PT; however, this begs the question of how the patches are being tested. Paolo
