[PATCH v2 2/3] perf/x86/intel: Do not deploy workaround when TSX is deprecated
From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Date: 2021-06-14 21:13:15
Also in:
linux-perf-users, lkml
Subsystem:
performance events subsystem, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Linus Torvalds, Thomas Gleixner, Borislav Petkov, Dave Hansen
Earlier workaround added by commit 400816f60c54 ("perf/x86/intel:
Implement support for TSX Force Abort") for perf counter interactions
[1] are not required on some client systems which received a microcode
update that deprecates TSX.
Bypass the perf workaround when such microcode is enumerated.
[1] Performance Monitoring Impact of Intel® Transactional Synchronization Extension Memory
http://cdrdv2.intel.com/v1/dl/getContent/604224 (Document ID 604224)
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Reviewed-by: Andi Kleen <redacted>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Neelima Krishnan <redacted>
---
arch/x86/events/intel/core.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index e28892270c58..b599a30fcc7d 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c@@ -6015,7 +6015,15 @@ __init int intel_pmu_init(void) tsx_attr = hsw_tsx_events_attrs; intel_pmu_pebs_data_source_skl(pmem); - if (boot_cpu_has(X86_FEATURE_TSX_FORCE_ABORT)) { + /* Processors with CPUID.RTM_ALWAYS_ABORT have TSX deprecated by + * default. TSX force abort hooks are not required on these + * systems. + * + * Only deploy the workaround when older microcode is detected + * i.e. !X86_FEATURE_RTM_ALWAYS_ABORT. + */ + if (boot_cpu_has(X86_FEATURE_TSX_FORCE_ABORT) && + !boot_cpu_has(X86_FEATURE_RTM_ALWAYS_ABORT)) { x86_pmu.flags |= PMU_FL_TFA; x86_pmu.get_event_constraints = tfa_get_event_constraints; x86_pmu.enable_all = intel_tfa_pmu_enable_all;
--
git-series 0.9.1