[PATCH] perf/x86/intel/uncore: fix nonexistent clockticks event for client uncore

[Kan Liang]

The clockticks event can only be used by the first Cbox pmu. Other
Cboxes don't allow to open clockticks event, eventhough it's announced
via /sys/../events/..

For client uncore, there is only one clocktick fixed counter. Current
kernel code forces that only the first box can access the fixed counter
in uncore_pmu_event_init. But it doesn't take care of the the
attr_groups. All the pmus of same type share the same attr_groups. If
the clockticks event is set for the first box, user can also observe the
event in other boxes.

The clocktick fixed counter is a standalone counter. It should be
removed from the Cbox PMUs. A new type of PMU is added which only
supports fixed counter events.

User observable changes with the patch.
clockticks event is removed from Cbox. It will return unsupported, if
uncore_cbox_0/clockticks/ is accessed. User may need to change their
script to use uncore_clock/clockticks/ to instead.

Signed-off-by: Kan Liang <kan.liang@xxxxxxxxx>
---
 arch/x86/events/intel/uncore.c     | 13 +++++++------
 arch/x86/events/intel/uncore_snb.c | 38 +++++++++++++++++++++++++++-----------
 2 files changed, 34 insertions(+), 17 deletions(-)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index dbaaf7dc..03afeca 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -652,6 +652,10 @@ static int uncore_pmu_event_init(struct perf_event *event)
 	if (hwc->sample_period)
 		return -EINVAL;
 
+	/* Single fixed PMU only has fixed event */
+	if (pmu->type->single_fixed && (event->attr.config != UNCORE_FIXED_EVENT))
+		return -EINVAL;
+
 	/*
 	 * Place all uncore events for a particular physical package
 	 * onto a single cpu
@@ -675,12 +679,9 @@ static int uncore_pmu_event_init(struct perf_event *event)
 		/* no fixed counter */
 		if (!pmu->type->fixed_ctl)
 			return -EINVAL;
-		/*
-		 * if there is only one fixed counter, only the first pmu
-		 * can access the fixed counter
-		 */
-		if (pmu->type->single_fixed && pmu->pmu_idx > 0)
-			return -EINVAL;
+
+		if (pmu->type->single_fixed)
+			event->hw.idx = UNCORE_PMC_IDX_FIXED;
 
 		/* fixed counters have event field hardcoded to zero */
 		hwc->config = 0ULL;
diff --git a/arch/x86/events/intel/uncore_snb.c b/arch/x86/events/intel/uncore_snb.c
index a3dcc12..1b037ea 100644
--- a/arch/x86/events/intel/uncore_snb.c
+++ b/arch/x86/events/intel/uncore_snb.c
@@ -117,7 +117,7 @@ static void snb_uncore_msr_exit_box(struct intel_uncore_box *box)
 }
 
 static struct uncore_event_desc snb_uncore_events[] = {
-	INTEL_UNCORE_EVENT_DESC(clockticks, "event=0xff,umask=0x00"),
+	INTEL_UNCORE_EVENT_DESC(clockticks, "event=0xff"),
 	{ /* end: all zeroes */ },
 };
 
@@ -155,17 +155,12 @@ static struct intel_uncore_type snb_uncore_cbox = {
 	.num_counters   = 2,
 	.num_boxes	= 4,
 	.perf_ctr_bits	= 44,
-	.fixed_ctr_bits	= 48,
 	.perf_ctr	= SNB_UNC_CBO_0_PER_CTR0,
 	.event_ctl	= SNB_UNC_CBO_0_PERFEVTSEL0,
-	.fixed_ctr	= SNB_UNC_FIXED_CTR,
-	.fixed_ctl	= SNB_UNC_FIXED_CTR_CTRL,
-	.single_fixed	= 1,
 	.event_mask	= SNB_UNC_RAW_EVENT_MASK,
 	.msr_offset	= SNB_UNC_CBO_MSR_OFFSET,
 	.ops		= &snb_uncore_msr_ops,
 	.format_group	= &snb_uncore_format_group,
-	.event_descs	= snb_uncore_events,
 };
 
 static struct intel_uncore_type snb_uncore_arb = {
@@ -182,9 +177,34 @@ static struct intel_uncore_type snb_uncore_arb = {
 	.format_group	= &snb_uncore_format_group,
 };
 
+static struct attribute *snb_uncore_clock_formats_attr[] = {
+	&format_attr_event.attr,
+	NULL,
+};
+
+static struct attribute_group snb_uncore_clock_format_group = {
+	.name = "format",
+	.attrs = snb_uncore_clock_formats_attr,
+};
+
+static struct intel_uncore_type snb_uncore_clockbox = {
+	.name		= "clock",
+	.num_counters   = 1,
+	.num_boxes	= 1,
+	.fixed_ctr_bits	= 48,
+	.fixed_ctr	= SNB_UNC_FIXED_CTR,
+	.fixed_ctl	= SNB_UNC_FIXED_CTR_CTRL,
+	.single_fixed	= 1,
+	.event_mask	= SNB_UNC_CTL_EV_SEL_MASK,
+	.format_group	= &snb_uncore_clock_format_group,
+	.ops		= &snb_uncore_msr_ops,
+	.event_descs	= snb_uncore_events,
+};
+
 static struct intel_uncore_type *snb_msr_uncores[] = {
 	&snb_uncore_cbox,
 	&snb_uncore_arb,
+	&snb_uncore_clockbox,
 	NULL,
 };
 
@@ -229,22 +249,18 @@ static struct intel_uncore_type skl_uncore_cbox = {
 	.num_counters   = 4,
 	.num_boxes	= 5,
 	.perf_ctr_bits	= 44,
-	.fixed_ctr_bits	= 48,
 	.perf_ctr	= SNB_UNC_CBO_0_PER_CTR0,
 	.event_ctl	= SNB_UNC_CBO_0_PERFEVTSEL0,
-	.fixed_ctr	= SNB_UNC_FIXED_CTR,
-	.fixed_ctl	= SNB_UNC_FIXED_CTR_CTRL,
-	.single_fixed	= 1,
 	.event_mask	= SNB_UNC_RAW_EVENT_MASK,
 	.msr_offset	= SNB_UNC_CBO_MSR_OFFSET,
 	.ops		= &skl_uncore_msr_ops,
 	.format_group	= &snb_uncore_format_group,
-	.event_descs	= snb_uncore_events,
 };
 
 static struct intel_uncore_type *skl_msr_uncores[] = {
 	&skl_uncore_cbox,
 	&snb_uncore_arb,
+	&snb_uncore_clockbox,
 	NULL,
 };
 
-- 
2.4.3