[PATCH v2] powerpc/perf: Add constraints for power9 l2/l3 bus events

[PATCH v2] powerpc/perf: Add constraints for power9 l2/l3 bus events

[Madhavan Srinivasan]

In Power9, L2/L3 bus events are always available as a
"bank" of 4 events. To obtain the counts for any of the
l2/l3 bus events in a given bank, the user will have to
program PMC4 with corresponding l2/l3 bus event for that
bank. Patch add a mask and a new pass to updates the mask
for each PMU used by L2/L3 bus events and checks the mask
to enforce it.

Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
---
Changelog v1:
Removed the callback and added a new pass

 arch/powerpc/perf/isa207-common.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/perf/isa207-common.c b/arch/powerpc/perf/isa207-common.c
index 50e598cf644b..ce12e93dbd16 100644
--- a/arch/powerpc/perf/isa207-common.c
+++ b/arch/powerpc/perf/isa207-common.c
@@ -219,7 +219,7 @@ int isa207_compute_mmcr(u64 event[], int n_ev,
 			       struct perf_event *pevents[])
 {
 	unsigned long mmcra, mmcr1, mmcr2, unit, combine, psel, cache, val;
-	unsigned int pmc, pmc_inuse;
+	unsigned int pmc, pmc_inuse, mask=0;
 	int i;
 
 	pmc_inuse = 0;
@@ -312,6 +312,24 @@ int isa207_compute_mmcr(u64 event[], int n_ev,
 		hwc[i] = pmc - 1;
 	}
 
+/*
+ * Pass 3: to Check for l2/l3 bus event rule. PMC4
+ * must be programmed to use L2/L3 bus events in any other PMC[1/2/3]s
+ */
+	if (cpu_has_feature(CPU_FTR_ARCH_300)) {
+		for (i = 0; i < n_ev; ++i) {
+			pmc     = (event[i] >> EVENT_PMC_SHIFT) & EVENT_PMC_MASK;
+			unit    = (event[i] >> EVENT_UNIT_SHIFT) & EVENT_UNIT_MASK;
+			if (unit >= 6 && unit <= 9)
+				mask |= 1 << (pmc - 1);
+		}
+
+		if ((mask) && ((mask & 0xf) < 0x8)) {
+			printk(KERN_ERR "Missing PMC4 L2/L3 Bus event\n");
+			return -1;
+		}
+	}
+
 	/* Return MMCRx values */
 	mmcr[0] = 0;
 
-- 
2.7.4