From: Peter Zijlstra <peterz@infradead.org>
To: "Wang, Wei W" <wei.w.wang@intel.com>
Cc: "Liang, Kan" <kan.liang@linux.intel.com>,
"Li, Xiaoyao" <xiaoyao.li@intel.com>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
"Christopherson,, Sean" <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
"linux-perf-users@vger.kernel.org"
<linux-perf-users@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [RFC PATCH v2 2/3] perf/x86/intel/pt: Introduce and export pt_get_curr_event()
Date: Thu, 22 Sep 2022 16:09:32 +0200 [thread overview]
Message-ID: <YyxsnAFYMLn2U9BT@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <DS0PR11MB637346E9F224C5330CDEF3BFDC4E9@DS0PR11MB6373.namprd11.prod.outlook.com>
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.
next prev parent reply other threads:[~2022-09-22 14:09 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-21 16:45 [RFC PATCH v2 0/3] KVM: VMX: Fix VM entry failure on PT_MODE_HOST_GUEST while host is using PT Xiaoyao Li
2022-09-21 16:45 ` [RFC PATCH v2 1/3] perf/core: Expose perf_event_{en,dis}able_local() Xiaoyao Li
2022-09-22 12:16 ` Wang, Wei W
2022-09-21 16:45 ` [RFC PATCH v2 2/3] perf/x86/intel/pt: Introduce and export pt_get_curr_event() Xiaoyao Li
2022-09-22 5:14 ` Xiaoyao Li
2022-09-22 12:33 ` Liang, Kan
2022-09-22 12:58 ` Wang, Wei W
2022-09-22 13:34 ` Peter Zijlstra
2022-09-22 13:59 ` Wang, Wei W
2022-09-22 14:09 ` Peter Zijlstra [this message]
2022-09-22 14:42 ` Wang, Wei W
2022-09-26 15:48 ` Liang, Kan
2022-09-26 17:24 ` Jim Mattson
2022-09-26 18:08 ` Liang, Kan
2022-09-27 14:27 ` Wang, Wei W
2022-09-27 16:52 ` Liang, Kan
2022-09-26 15:32 ` Liang, Kan
2022-09-21 16:45 ` [RFC PATCH v2 3/3] KVM: VMX: Stop/resume host PT before/after VMX transition when PT_MODE_HOST_GUEST Xiaoyao Li
2022-09-22 12:34 ` Wang, Wei W
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