On Mon, Sep 26, 2022 at 9:55 AM Liang, Kan <kan.liang@xxxxxxxxxxxxxxx> wrote: > > > > On 2022-09-22 10:42 a.m., Wang, Wei W wrote: > > On Thursday, September 22, 2022 10:10 PM, Peter Zijlstra wrote: > >> On Thu, Sep 22, 2022 at 01:59:53PM +0000, Wang, Wei W wrote: > >>> On Thursday, September 22, 2022 9:35 PM, Peter Zijlstra > >>>> On Thu, Sep 22, 2022 at 12:58:49PM +0000, Wang, Wei W wrote: > >>>> > >>>>> Add a function to expose the current running PT event to users. > >>>>> One usage is in KVM, it needs to get and disable the running host > >>>>> PT event before VMEnter to the guest and resumes the event after > >> VMexit to host. > >>>> > >>>> You cannot just kill a host event like that. If there is a host > >>>> event, the guest looses out. > >>> > >>> OK. The intention was to pause the event (that only profiles host > >>> info) when switching to guest, and resume when switching back to host. > >> > >> If the even doesn't profile guest context, then yes. If it does profile guest > >> context, you can't. > > > > Seems better to add this one: > > If the guest host mode is enabled, I think the PT driver should not > allow the perf tool to create a host event with !exclude_guest. While I agree that guest events should generally have priority over host events, this is not consistent with the way "normal" PMU events are handled.
