[PATCH 2/6] perf/amd/ibs: Advertise zen4_ibs_extensions as pmu capability attribute

[Ravi Bangoria]

PMU driver can advertise certain feature via capability attribute('caps'
sysfs directory) which can be consumed by userspace tools like perf. Add
zen4_ibs_extensions capability attribute for IBS pmus. This attribute
will be enabled when CPUID_Fn8000001B_EAX[11] is set.

Without patch:

  $ ls /sys/bus/event_source/devices/ibs_op/caps
  ls: cannot access '/sys/.../ibs_op/caps': No such file or directory

With patch:

  $ ls /sys/bus/event_source/devices/ibs_op/caps
  zen4_ibs_extensions

Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxx>
---
 arch/x86/events/amd/ibs.c | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
index a5303d62060c..54e12bd7843e 100644
--- a/arch/x86/events/amd/ibs.c
+++ b/arch/x86/events/amd/ibs.c
@@ -95,8 +95,10 @@ struct perf_ibs {
 	struct cpu_perf_ibs __percpu	*pcpu;
 
 	struct attribute		**format_attrs;
+	struct attribute		**caps_attrs;
 	struct attribute_group		format_group;
-	const struct attribute_group	*attr_groups[2];
+	struct attribute_group		caps_group;
+	const struct attribute_group	*attr_groups[3];
 
 	u64				(*get_count)(u64 config);
 };
@@ -522,10 +524,13 @@ PMU_FORMAT_ATTR(rand_en,	"config:57");
 PMU_FORMAT_ATTR(cnt_ctl,	"config:19");
 PMU_EVENT_ATTR_STRING(l3missonly, fetch_l3missonly, "config:59");
 PMU_EVENT_ATTR_STRING(l3missonly, op_l3missonly, "config:16");
+PMU_EVENT_ATTR_STRING(zen4_ibs_extensions, zen4_ibs_extensions, "1");
 
 /* size = nr attrs plus NULL at the end */
 static struct attribute *ibs_fetch_format_attrs[3];
 static struct attribute *ibs_op_format_attrs[3];
+static struct attribute *ibs_fetch_caps_attrs[2];
+static struct attribute *ibs_op_caps_attrs[2];
 
 static struct perf_ibs perf_ibs_fetch = {
 	.pmu = {
@@ -548,6 +553,7 @@ static struct perf_ibs perf_ibs_fetch = {
 	.offset_mask		= { MSR_AMD64_IBSFETCH_REG_MASK },
 	.offset_max		= MSR_AMD64_IBSFETCH_REG_COUNT,
 	.format_attrs		= ibs_fetch_format_attrs,
+	.caps_attrs		= ibs_fetch_caps_attrs,
 
 	.get_count		= get_ibs_fetch_count,
 };
@@ -574,6 +580,7 @@ static struct perf_ibs perf_ibs_op = {
 	.offset_mask		= { MSR_AMD64_IBSOP_REG_MASK },
 	.offset_max		= MSR_AMD64_IBSOP_REG_COUNT,
 	.format_attrs		= ibs_op_format_attrs,
+	.caps_attrs		= ibs_op_caps_attrs,
 
 	.get_count		= get_ibs_op_count,
 };
@@ -728,6 +735,7 @@ static __init int perf_ibs_pmu_init(struct perf_ibs *perf_ibs, char *name)
 {
 	struct cpu_perf_ibs __percpu *pcpu;
 	int ret;
+	int i = 0;
 
 	pcpu = alloc_percpu(struct cpu_perf_ibs);
 	if (!pcpu)
@@ -736,16 +744,26 @@ static __init int perf_ibs_pmu_init(struct perf_ibs *perf_ibs, char *name)
 	perf_ibs->pcpu = pcpu;
 
 	/* register attributes */
+	memset(&perf_ibs->attr_groups, 0, sizeof(perf_ibs->attr_groups));
 	if (perf_ibs->format_attrs[0]) {
 		memset(&perf_ibs->format_group, 0, sizeof(perf_ibs->format_group));
-		perf_ibs->format_group.name	= "format";
-		perf_ibs->format_group.attrs	= perf_ibs->format_attrs;
+		perf_ibs->format_group.name = "format";
+		perf_ibs->format_group.attrs = perf_ibs->format_attrs;
 
-		memset(&perf_ibs->attr_groups, 0, sizeof(perf_ibs->attr_groups));
-		perf_ibs->attr_groups[0]	= &perf_ibs->format_group;
-		perf_ibs->pmu.attr_groups	= perf_ibs->attr_groups;
+		perf_ibs->attr_groups[i++] = &perf_ibs->format_group;
 	}
 
+	if (perf_ibs->caps_attrs[0]) {
+		memset(&perf_ibs->caps_group, 0, sizeof(perf_ibs->caps_group));
+		perf_ibs->caps_group.name = "caps";
+		perf_ibs->caps_group.attrs = perf_ibs->caps_attrs;
+
+		perf_ibs->attr_groups[i++] = &perf_ibs->caps_group;
+	}
+
+	if (i)
+		perf_ibs->pmu.attr_groups = perf_ibs->attr_groups;
+
 	ret = perf_pmu_register(&perf_ibs->pmu, name, -1);
 	if (ret) {
 		perf_ibs->pcpu = NULL;
@@ -758,6 +776,7 @@ static __init int perf_ibs_pmu_init(struct perf_ibs *perf_ibs, char *name)
 static __init void perf_ibs_fetch_prepare(void)
 {
 	struct attribute **format_attrs = perf_ibs_fetch.format_attrs;
+	struct attribute **caps_attr = perf_ibs_fetch.caps_attrs;
 
 	/*
 	 * Some chips fail to reset the fetch count when it is written; instead
@@ -773,6 +792,7 @@ static __init void perf_ibs_fetch_prepare(void)
 	if (ibs_caps & IBS_CAPS_ZEN4IBSEXTENSIONS) {
 		perf_ibs_fetch.config_mask |= IBS_FETCH_L3MISSONLY;
 		*format_attrs++ = &fetch_l3missonly.attr.attr;
+		*caps_attr++ = &zen4_ibs_extensions.attr.attr;
 	}
 
 	perf_ibs_pmu_init(&perf_ibs_fetch, "ibs_fetch");
@@ -781,6 +801,7 @@ static __init void perf_ibs_fetch_prepare(void)
 static __init void perf_ibs_op_prepare(void)
 {
 	struct attribute **format_attrs = perf_ibs_op.format_attrs;
+	struct attribute **caps_attr = perf_ibs_op.caps_attrs;
 
 	if (ibs_caps & IBS_CAPS_OPCNT) {
 		perf_ibs_op.config_mask |= IBS_OP_CNT_CTL;
@@ -796,6 +817,7 @@ static __init void perf_ibs_op_prepare(void)
 	if (ibs_caps & IBS_CAPS_ZEN4IBSEXTENSIONS) {
 		perf_ibs_op.config_mask |= IBS_OP_L3MISSONLY;
 		*format_attrs++ = &op_l3missonly.attr.attr;
+		*caps_attr++ = &zen4_ibs_extensions.attr.attr;
 	}
 
 	perf_ibs_pmu_init(&perf_ibs_op, "ibs_op");
-- 
2.27.0