[PATCH v3] perf: honoring the architectural performance monitoring version

[Imre Palik]

From: "Palik, Imre" <imrep@xxxxxxxxx>

Architectural performance monitoring version 1 doesn't support fixed
counters.  Currently, even if a hypervisor advertises support for
architectural performance monitoring version 1, perf may still tries to use
the fixed counters, as the constraints are set up based on the CPU model.

This patch ensures that perf honors the architectural performance
monitoring version returned by CPUID, and it only uses the fixed counters
for version two and above.

Some of the ideas in this patch are coming from Peter Zijlstra.

Signed-off-by: Imre Palik <imrep@xxxxxxxxx>
Cc: Anthony Liguori <aliguori@xxxxxxxxxx>
---
 arch/x86/kernel/cpu/perf_event_intel.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index a1e35c9..c54bb97 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -3322,13 +3322,14 @@ __init int intel_pmu_init(void)
 		 * counter, so do not extend mask to generic counters
 		 */
 		for_each_event_constraint(c, x86_pmu.event_constraints) {
-			if (c->cmask != FIXED_EVENT_FLAGS
-			    || c->idxmsk64 == INTEL_PMC_MSK_FIXED_REF_CYCLES) {
-				continue;
+			if (c->cmask == FIXED_EVENT_FLAGS
+			    && c->idxmsk64 != INTEL_PMC_MSK_FIXED_REF_CYCLES) {
+				c->idxmsk64 |=
+					(1ULL << x86_pmu.num_counters) - 1;
 			}
-
-			c->idxmsk64 |= (1ULL << x86_pmu.num_counters) - 1;
-			c->weight += x86_pmu.num_counters;
+			c->idxmsk64 &=
+				~(~0UL << (INTEL_PMC_IDX_FIXED + x86_pmu.num_counters_fixed));
+			c->weight = hweight64(c->idxmsk64);
 		}
 	}
 
-- 
1.7.9.5

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/