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References: <20240126085444.324918-1-xiong.y.zhang@linux.intel.com> <20240126085444.324918-3-xiong.y.zhang@linux.intel.com>
In-Reply-To: <20240126085444.324918-3-xiong.y.zhang@linux.intel.com>
From: Raghavendra Rao Ananta <rananta@google.com>
Date: Wed, 20 Mar 2024 09:40:31 -0700
Message-ID: <CAJHc60ww7cOhtbWNp9WP7bxWKXCZtcT=6e4Fk2TaB63YqWMWbw@mail.gmail.com>
Subject: Re: [RFC PATCH 02/41] perf: Support guest enter/exit interfaces
To: Xiong Zhang <xiong.y.zhang@linux.intel.com>
Cc: seanjc@google.com, pbonzini@redhat.com, peterz@infradead.org, 
	mizhang@google.com, kan.liang@intel.com, zhenyuw@linux.intel.com, 
	dapeng1.mi@linux.intel.com, jmattson@google.com, kvm@vger.kernel.org, 
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, 
	zhiyuan.lv@intel.com, eranian@google.com, irogers@google.com, 
	samantha.alt@intel.com, like.xu.linux@gmail.com, chao.gao@intel.com, 
	Kan Liang <kan.liang@linux.intel.com>
Content-Type: text/plain; charset="UTF-8"

Hi Kan,

>
> +static void __perf_force_exclude_guest_pmu(struct perf_event_pmu_context *pmu_ctx,
> +                                          struct perf_event *event)
> +{
> +       struct perf_event_context *ctx = pmu_ctx->ctx;
> +       struct perf_event *sibling;
> +       bool include_guest = false;
> +
> +       event_sched_out(event, ctx);
> +       if (!event->attr.exclude_guest)
> +               include_guest = true;
> +       for_each_sibling_event(sibling, event) {
> +               event_sched_out(sibling, ctx);
> +               if (!sibling->attr.exclude_guest)
> +                       include_guest = true;
> +       }
> +       if (include_guest) {
> +               perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
> +               for_each_sibling_event(sibling, event)
> +                       perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
> +       }
Does the perf core revert the PERF_EVENT_STATE_ERROR state somewhere
from the perf_guest_exit() path, or is it expected to remain in this
state?
IIUC, in the perf_guest_exit() path, when we land into
merge_sched_in(), we never schedule the event back if event->state <=
PERF_EVENT_STATE_OFF.

Thank you.
Raghavendra