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X-CSE-ConnectionGUID: FmiBS8CIQdO2cVMo7D3tvg== X-CSE-MsgGUID: zVJ9Is3qSLGNxtVoONh2Xg== X-IronPort-AV: E=McAfee;i="6700,10204,11241"; a="40600276" X-IronPort-AV: E=Sophos;i="6.11,245,1725346800"; d="scan'208";a="40600276" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Oct 2024 06:16:14 -0700 X-CSE-ConnectionGUID: eIQ0vLyOSf+/ryrVmuucxQ== X-CSE-MsgGUID: PB5SoMk1SGS1rKirHLZUYg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.11,245,1725346800"; d="scan'208";a="82728993" Received: from ahunter6-mobl1.ger.corp.intel.com (HELO [10.0.2.15]) ([10.245.115.59]) by orviesa007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Oct 2024 06:16:06 -0700 Message-ID: <7bacbe72-c283-453b-bf1f-6ba05b68cac8@intel.com> Date: Wed, 30 Oct 2024 15:16:00 +0200 Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V14 00/11] perf/core: Add ability for an event to "pause" or "resume" AUX area tracing From: Adrian Hunter To: Peter Zijlstra Cc: Ingo Molnar , Mark Rutland , Alexander Shishkin , Heiko Carstens , Thomas Richter , Hendrik Brueckner , Suzuki K Poulose , Mike Leach , James Clark , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, Yicong Yang , Jonathan Cameron , Will Deacon , Arnaldo Carvalho de Melo , Jiri Olsa , Namhyung Kim , Ian Rogers , Andi Kleen , Thomas Gleixner , Borislav Petkov , Dave Hansen , x86@kernel.org, H Peter Anvin , Kan Liang , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org References: <20241022155920.17511-1-adrian.hunter@intel.com> Content-Language: en-US Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki In-Reply-To: <20241022155920.17511-1-adrian.hunter@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 22/10/24 18:59, Adrian Hunter wrote: > Hi > > Note for V14: > KVM patches dropped. ping > > Note for V12: > There was a small conflict between the Intel PT changes in > "KVM: x86: Fix Intel PT Host/Guest mode when host tracing" and the > changes in this patch set, so I have put the patch sets together, > along with outstanding fix "perf/x86/intel/pt: Fix buffer full but > size is 0 case" > > Cover letter for KVM changes (patches 2 to 4): > > There is a long-standing problem whereby running Intel PT on host and guest > in Host/Guest mode, causes VM-Entry failure. > > The motivation for this patch set is to provide a fix for stable kernels > prior to the advent of the "Mediated Passthrough vPMU" patch set: > > https://lore.kernel.org/kvm/20240801045907.4010984-1-mizhang@google.com/ > > which would render a large part of the fix unnecessary but likely not be > suitable for backport to stable due to its size and complexity. > > Ideally, this patch set would be applied before "Mediated Passthrough vPMU" > > Note that the fix does not conflict with "Mediated Passthrough vPMU", it > is just that "Mediated Passthrough vPMU" will make the code to stop and > restart Intel PT unnecessary. > > Note for V11: > Moving aux_paused into a union within struct hw_perf_event caused > a regression because aux_paused was being written unconditionally > even though it is valid only for AUX (e.g. Intel PT) PMUs. > That is fixed in V11. > > Hardware traces, such as instruction traces, can produce a vast amount of > trace data, so being able to reduce tracing to more specific circumstances > can be useful. > > The ability to pause or resume tracing when another event happens, can do > that. > > These patches add such a facilty and show how it would work for Intel > Processor Trace. > > Maintainers of other AUX area tracing implementations are requested to > consider if this is something they might employ and then whether or not > the ABI would work for them. Note, thank you to James Clark (ARM) for > evaluating the API for Coresight. Suzuki K Poulose (ARM) also responded > positively to the RFC. > > Changes to perf tools are now (since V4) fleshed out. > > Please note, Intel® Architecture Instruction Set Extensions and Future > Features Programming Reference March 2024 319433-052, currently: > > https://cdrdv2.intel.com/v1/dl/getContent/671368 > > introduces hardware pause / resume for Intel PT in a feature named > Intel PT Trigger Tracing. > > For that more fields in perf_event_attr will be necessary. The main > differences are: > - it can be applied not just to overflows, but optionally to > every event > - a packet is emitted into the trace, optionally with IP > information > - no PMI > - works with PMC and DR (breakpoint) events only > > Here are the proposed additions to perf_event_attr, please comment: > > diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h > index 0c557f0a17b3..05dcc43f11bb 100644 > --- a/tools/include/uapi/linux/perf_event.h > +++ b/tools/include/uapi/linux/perf_event.h > @@ -369,6 +369,22 @@ enum perf_event_read_format { > PERF_FORMAT_MAX = 1U << 5, /* non-ABI */ > }; > > +enum { > + PERF_AUX_ACTION_START_PAUSED = 1U << 0, > + PERF_AUX_ACTION_PAUSE = 1U << 1, > + PERF_AUX_ACTION_RESUME = 1U << 2, > + PERF_AUX_ACTION_EMIT = 1U << 3, > + PERF_AUX_ACTION_NR = 0x1f << 4, > + PERF_AUX_ACTION_NO_IP = 1U << 9, > + PERF_AUX_ACTION_PAUSE_ON_EVT = 1U << 10, > + PERF_AUX_ACTION_RESUME_ON_EVT = 1U << 11, > + PERF_AUX_ACTION_EMIT_ON_EVT = 1U << 12, > + PERF_AUX_ACTION_NR_ON_EVT = 0x1f << 13, > + PERF_AUX_ACTION_NO_IP_ON_EVT = 1U << 18, > + PERF_AUX_ACTION_MASK = ~PERF_AUX_ACTION_START_PAUSED, > + PERF_AUX_PAUSE_RESUME_MASK = PERF_AUX_ACTION_PAUSE | PERF_AUX_ACTION_RESUME, > +}; > + > #define PERF_ATTR_SIZE_VER0 64 /* sizeof first published struct */ > #define PERF_ATTR_SIZE_VER1 72 /* add: config2 */ > #define PERF_ATTR_SIZE_VER2 80 /* add: branch_sample_type */ > @@ -515,10 +531,19 @@ struct perf_event_attr { > union { > __u32 aux_action; > struct { > - __u32 aux_start_paused : 1, /* start AUX area tracing paused */ > - aux_pause : 1, /* on overflow, pause AUX area tracing */ > - aux_resume : 1, /* on overflow, resume AUX area tracing */ > - __reserved_3 : 29; > + __u32 aux_start_paused : 1, /* start AUX area tracing paused */ > + aux_pause : 1, /* on overflow, pause AUX area tracing */ > + aux_resume : 1, /* on overflow, resume AUX area tracing */ > + aux_emit : 1, /* generate AUX records instead of events */ > + aux_nr : 5, /* AUX area tracing reference number */ > + aux_no_ip : 1, /* suppress IP in AUX records */ > + /* Following apply to event occurrence not overflows */ > + aux_pause_on_evt : 1, /* on event, pause AUX area tracing */ > + aux_resume_on_evt : 1, /* on event, resume AUX area tracing */ > + aux_emit_on_evt : 1, /* generate AUX records instead of events */ > + aux_nr_on_evt : 5, /* AUX area tracing reference number */ > + aux_no_ip_on_evt : 1, /* suppress IP in AUX records */ > + __reserved_3 : 13; > }; > }; > > > Changes in V14: > Dropped KVM patches > > perf/x86/intel/pt: Add support for pause / resume > Set pt->handle_nmi after configuration is completed instead of during > > Changes in V13: > perf/core: Add aux_pause, aux_resume, aux_start_paused > Do aux_resume at the end of __perf_event_overflow() so as to trace > less of perf itself > > perf tools: Add missing_features for aux_start_paused, aux_pause, aux_resume > Add error message also in EOPNOTSUPP case (Leo) > > Changes in V12: > Add previously sent patch "perf/x86/intel/pt: Fix buffer full > but size is 0 case" > > Add previously sent patch set "KVM: x86: Fix Intel PT Host/Guest > mode when host tracing" > > Rebase on current tip plus patch set "KVM: x86: Fix Intel PT Host/Guest > mode when host tracing" > > Changes in V11: > perf/core: Add aux_pause, aux_resume, aux_start_paused > Make assignment to event->hw.aux_paused conditional on > (pmu->capabilities & PERF_PMU_CAP_AUX_PAUSE). > > perf/x86/intel: Do not enable large PEBS for events with aux actions or aux sampling > Remove definition of has_aux_action() because it has > already been added as an inline function. > > perf/x86/intel/pt: Fix sampling synchronization > perf tools: Enable evsel__is_aux_event() to work for ARM/ARM64 > perf tools: Enable evsel__is_aux_event() to work for S390_CPUMSF > Dropped because they have already been applied > > Changes in V10: > perf/core: Add aux_pause, aux_resume, aux_start_paused > Move aux_paused into a union within struct hw_perf_event. > Additional comment wrt PERF_EF_PAUSE/PERF_EF_RESUME. > Factor out has_aux_action() as an inline function. > Use scoped_guard for irqsave. > Move calls of perf_event_aux_pause() from __perf_event_output() > to __perf_event_overflow(). > > Changes in V9: > perf/x86/intel/pt: Fix sampling synchronization > New patch > > perf/core: Add aux_pause, aux_resume, aux_start_paused > Move aux_paused to struct hw_perf_event > > perf/x86/intel/pt: Add support for pause / resume > Add more comments and barriers for resume_allowed and > pause_allowed > Always use WRITE_ONCE with resume_allowed > > > Changes in V8: > > perf tools: Parse aux-action > Fix clang warning: > util/auxtrace.c:821:7: error: missing field 'aux_action' initializer [-Werror,-Wmissing-field-initializers] > 821 | {NULL}, > | ^ > > Changes in V7: > > Add Andi's Reviewed-by for patches 2-12 > Re-base > > Changes in V6: > > perf/core: Add aux_pause, aux_resume, aux_start_paused > Removed READ/WRITE_ONCE from __perf_event_aux_pause() > Expanded comment about guarding against NMI > > Changes in V5: > > perf/core: Add aux_pause, aux_resume, aux_start_paused > Added James' Ack > > perf/x86/intel: Do not enable large PEBS for events with aux actions or aux sampling > New patch > > perf tools > Added Ian's Ack > > Changes in V4: > > perf/core: Add aux_pause, aux_resume, aux_start_paused > Rename aux_output_cfg -> aux_action > Reorder aux_action bits from: > aux_pause, aux_resume, aux_start_paused > to: > aux_start_paused, aux_pause, aux_resume > Fix aux_action bits __u64 -> __u32 > > coresight: Have a stab at support for pause / resume > Dropped > > perf tools > All new patches > > Changes in RFC V3: > > coresight: Have a stab at support for pause / resume > 'mode' -> 'flags' so it at least compiles > > Changes in RFC V2: > > Use ->stop() / ->start() instead of ->pause_resume() > Move aux_start_paused bit into aux_output_cfg > Tighten up when Intel PT pause / resume is allowed > Add an example of how it might work for CoreSight > > > Adrian Hunter (11): > perf/x86/intel/pt: Fix buffer full but size is 0 case > perf/core: Add aux_pause, aux_resume, aux_start_paused > perf/x86/intel/pt: Add support for pause / resume > perf/x86/intel: Do not enable large PEBS for events with aux actions or aux sampling > perf tools: Add aux_start_paused, aux_pause and aux_resume > perf tools: Add aux-action config term > perf tools: Parse aux-action > perf tools: Add missing_features for aux_start_paused, aux_pause, aux_resume > perf intel-pt: Improve man page format > perf intel-pt: Add documentation for pause / resume > perf intel-pt: Add a test for pause / resume > > arch/x86/events/intel/core.c | 4 +- > arch/x86/events/intel/pt.c | 84 +++- > arch/x86/events/intel/pt.h | 6 + > include/linux/perf_event.h | 28 ++ > include/uapi/linux/perf_event.h | 11 +- > kernel/events/core.c | 75 +++- > kernel/events/internal.h | 1 + > tools/include/uapi/linux/perf_event.h | 11 +- > tools/perf/Documentation/perf-intel-pt.txt | 596 ++++++++++++++++++----------- > tools/perf/Documentation/perf-record.txt | 4 + > tools/perf/builtin-record.c | 4 +- > tools/perf/tests/shell/test_intel_pt.sh | 28 ++ > tools/perf/util/auxtrace.c | 67 +++- > tools/perf/util/auxtrace.h | 6 +- > tools/perf/util/evsel.c | 15 + > tools/perf/util/evsel.h | 1 + > tools/perf/util/evsel_config.h | 1 + > tools/perf/util/parse-events.c | 10 + > tools/perf/util/parse-events.h | 1 + > tools/perf/util/parse-events.l | 1 + > tools/perf/util/perf_event_attr_fprintf.c | 3 + > tools/perf/util/pmu.c | 1 + > 22 files changed, 716 insertions(+), 242 deletions(-) > > > Regards > Adrian