Eric Lee / smarc-ti-linux-kernel

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Commit 2968314094d8db0af32de20ad51349a30ea54a01

Authored by Venkatesh Srinivas
Committed by Greg Kroah-Hartman
1 parent 763e95c4ac
Exists in ti-linux-3.14.y and in 2 other branches processor-sdk-linux-01.00.00, smarc-ti-linux-3.14.y

perf/x86/intel: Use rdmsrl_safe() when initializing RAPL PMU 

commit 24223657806a0ebd0ae5c9caaf7b021091889cf2 upstream.

CPUs which should support the RAPL counters according to
Family/Model/Stepping may still issue #GP when attempting to access
the RAPL MSRs. This may happen when Linux is running under KVM and
we are passing-through host F/M/S data, for example. Use rdmsrl_safe
to first access the RAPL_POWER_UNIT MSR; if this fails, do not
attempt to use this PMU.

Signed-off-by: Venkatesh Srinivas <venkateshs@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1394739386-22260-1-git-send-email-venkateshs@google.com
Cc: zheng.z.yan@intel.com
Cc: eranian@google.com
Cc: ak@linux.intel.com
Cc: linux-kernel@vger.kernel.org
[ The patch also silently fixes another bug: rapl_pmu_init() didn't handle the memory alloc failure case previously. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[backport by whissi]
Cc: Thomas D <whissi@whissi.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 1 changed file with 9 additions and 3 deletions Side-by-side Diff

arch/x86/kernel/cpu/perf_event_intel_rapl.c
Diff comments   View file @ 2968314
... ... @@ -511,6 +511,7 @@
511 511 struct rapl_pmu *pmu = per_cpu(rapl_pmu, cpu);
512 512 int phys_id = topology_physical_package_id(cpu);
513 513 u64 ms;
  514 + u64 msr_rapl_power_unit_bits;
514 515  
515 516 if (pmu)
516 517 return 0;
... ... @@ -518,6 +519,9 @@
518 519 if (phys_id < 0)
519 520 return -1;
520 521  
  522 + if (!rdmsrl_safe(MSR_RAPL_POWER_UNIT, &msr_rapl_power_unit_bits))
  523 + return -1;
  524 +
521 525 pmu = kzalloc_node(sizeof(*pmu), GFP_KERNEL, cpu_to_node(cpu));
522 526 if (!pmu)
523 527 return -1;
... ... @@ -531,8 +535,7 @@
531 535 *
532 536 * we cache in local PMU instance
533 537 */
534   - rdmsrl(MSR_RAPL_POWER_UNIT, pmu->hw_unit);
535   - pmu->hw_unit = (pmu->hw_unit >> 8) & 0x1FULL;
  538 + pmu->hw_unit = (msr_rapl_power_unit_bits >> 8) & 0x1FULL;
536 539 pmu->pmu = &rapl_pmu_class;
537 540  
538 541 /*
... ... @@ -649,7 +652,9 @@
649 652 get_online_cpus();
650 653  
651 654 for_each_online_cpu(cpu) {
652   - rapl_cpu_prepare(cpu);
  655 + ret = rapl_cpu_prepare(cpu);
  656 + if (ret)
  657 + goto out;
653 658 rapl_cpu_init(cpu);
654 659 }
655 660  
... ... @@ -672,6 +677,7 @@
672 677 hweight32(rapl_cntr_mask),
673 678 ktime_to_ms(pmu->timer_interval));
674 679  
  680 +out:
675 681 put_online_cpus();
676 682  
677 683 return 0;