Hi
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 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 (14): perf/x86/intel/pt: Fix buffer full but size is 0 case KVM: x86: Fix Intel PT IA32_RTIT_CTL MSR validation KVM: x86: Fix Intel PT Host/Guest mode when host tracing also KVM: selftests: Add guest Intel PT test 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 | 209 +++++++- arch/x86/events/intel/pt.h | 16 + arch/x86/include/asm/intel_pt.h | 4 + arch/x86/kvm/vmx/vmx.c | 26 +- arch/x86/kvm/vmx/vmx.h | 1 - include/linux/perf_event.h | 28 + include/uapi/linux/perf_event.h | 11 +- kernel/events/core.c | 72 ++- 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 | 13 +- 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 + tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/include/x86_64/processor.h | 1 + tools/testing/selftests/kvm/x86_64/intel_pt.c | 381 +++++++++++++ 28 files changed, 1238 insertions(+), 264 deletions(-) create mode 100644 tools/testing/selftests/kvm/x86_64/intel_pt.c
Regards Adrian