Messages in this thread | | | From | "Wang, Wei W" <> | Subject | RE: [RFC PATCH v2 2/3] perf/x86/intel/pt: Introduce and export pt_get_curr_event() | Date | Thu, 22 Sep 2022 13:59:53 +0000 |
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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.
I don't think it is proper to directly disable it via clear MSR_IA32_RTIT_CTL, e.g. there may be dangling PT bit in the interrupt status register, this invokes the PT interrupt handler to re-enable it (for more details about the issue please see patch 3 commit). Would you have any suggestions to pause it?
Thanks, Wei
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