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perf, x86: Fix Intel-nhm PMU programming errata workaround 

Fix the Errata AAK100/AAP53/BD53 workaround, the officialy documented
workaround we implemented in:

 11164cd: perf, x86: Add Nehelem PMU programming errata workaround

doesn't actually work fully and causes a stuck PMU state
under load and non-functioning perf profiling.

A functional workaround was found by trial & error.

Affects all Nehalem-class Intel PMUs.

Signed-off-by: Zhang Yanmin <yanmin_zhang@linux.intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1281073148.2125.63.camel@ymzhang.sh.intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <stable@kernel.org> # .35.x
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Zhang, Yanmin 2010-08-06 13:39:08 +08:00 committed by Ingo Molnar
parent 9d5f3714e4
commit 351af0725e
1 changed files with 69 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

93
arch/x86/kernel/cpu/perf_event_intel.c
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@ -491,33 +491,78 @@ static void intel_pmu_enable_all(int added)
* Intel Errata AAP53 (model 30)
* Intel Errata BD53 (model 44)
*
* These chips need to be 'reset' when adding counters by programming
* the magic three (non counting) events 0x4300D2, 0x4300B1 and 0x4300B5
* either in sequence on the same PMC or on different PMCs.
* The official story:
* These chips need to be 'reset' when adding counters by programming the
* magic three (non-counting) events 0x4300B5, 0x4300D2, and 0x4300B1 either
* in sequence on the same PMC or on different PMCs.
*
* In practise it appears some of these events do in fact count, and
* we need to programm all 4 events.
*/
static void intel_pmu_nhm_workaround(void)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
static const unsigned long nhm_magic[4] = {
0x4300B5,
0x4300D2,
0x4300B1,
0x4300B1
};
struct perf_event *event;
int i;
/*
* The Errata requires below steps:
* 1) Clear MSR_IA32_PEBS_ENABLE and MSR_CORE_PERF_GLOBAL_CTRL;
* 2) Configure 4 PERFEVTSELx with the magic events and clear
* the corresponding PMCx;
* 3) set bit0~bit3 of MSR_CORE_PERF_GLOBAL_CTRL;
* 4) Clear MSR_CORE_PERF_GLOBAL_CTRL;
* 5) Clear 4 pairs of ERFEVTSELx and PMCx;
*/
/*
* The real steps we choose are a little different from above.
* A) To reduce MSR operations, we don't run step 1) as they
* are already cleared before this function is called;
* B) Call x86_perf_event_update to save PMCx before configuring
* PERFEVTSELx with magic number;
* C) With step 5), we do clear only when the PERFEVTSELx is
* not used currently.
* D) Call x86_perf_event_set_period to restore PMCx;
*/
/* We always operate 4 pairs of PERF Counters */
for (i = 0; i < 4; i++) {
event = cpuc->events[i];
if (event)
x86_perf_event_update(event);
}
for (i = 0; i < 4; i++) {
wrmsrl(MSR_ARCH_PERFMON_EVENTSEL0 + i, nhm_magic[i]);
wrmsrl(MSR_ARCH_PERFMON_PERFCTR0 + i, 0x0);
}
wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, 0xf);
wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, 0x0);
for (i = 0; i < 4; i++) {
event = cpuc->events[i];
if (event) {
x86_perf_event_set_period(event);
__x86_pmu_enable_event(&event->hw,
ARCH_PERFMON_EVENTSEL_ENABLE);
} else
wrmsrl(MSR_ARCH_PERFMON_EVENTSEL0 + i, 0x0);
}
}
static void intel_pmu_nhm_enable_all(int added)
{
if (added) {
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
int i;
wrmsrl(MSR_ARCH_PERFMON_EVENTSEL0 + 0, 0x4300D2);
wrmsrl(MSR_ARCH_PERFMON_EVENTSEL0 + 1, 0x4300B1);
wrmsrl(MSR_ARCH_PERFMON_EVENTSEL0 + 2, 0x4300B5);
wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, 0x3);
wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, 0x0);
for (i = 0; i < 3; i++) {
struct perf_event *event = cpuc->events[i];
if (!event)
continue;
__x86_pmu_enable_event(&event->hw,
ARCH_PERFMON_EVENTSEL_ENABLE);
}
}
if (added)
intel_pmu_nhm_workaround();
intel_pmu_enable_all(added);
}