[RFC PATCH v3 06/17] x86/resctrl: Introduce interface to display number of ABMC counters

[Babu Moger]

The ABMC feature provides an option to the user to pin (or assign) the
RMID to the hardware counter and monitor the bandwidth for a longer
duration. There are only a limited number of hardware counters.

Provide the interface to display the number of ABMC counters supported.

Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
v3: Changed the field name to mbm_assign_cntrs.

v2: Changed the field name to mbm_assignable_counters from abmc_counters.
---
 Documentation/arch/x86/resctrl.rst     |  4 ++++
 arch/x86/kernel/cpu/resctrl/monitor.c  |  1 +
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 16 ++++++++++++++++
 3 files changed, 21 insertions(+)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index cd973a013525..e06ffddb64f6 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -262,6 +262,10 @@ with the following files:
 	Reports the list of assignable features supported and the enclosed brackets
 	indicate the feature is enabled.
 
+"mbm_assign_cntrs":
+	The number of assignable counters available when the assignable monitoring
+	feature is supported.
+
 "max_threshold_occupancy":
 		Read/write file provides the largest value (in
 		bytes) at which a previously used LLC_occupancy
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 48d1957ea5a3..56dc49021540 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -1061,6 +1061,7 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 		if (resctrl_arch_has_abmc(r)) {
 			r->mbm_assign_capable = ABMC_ASSIGN;
 			resctrl_file_fflags_init("mbm_assign", RFTYPE_MON_INFO);
+			resctrl_file_fflags_init("mbm_assign_cntrs", RFTYPE_MON_INFO);
 		}
 	}
 
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 5ec807e8dd38..05f551bc316e 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -857,6 +857,16 @@ static int rdtgroup_mbm_assign_show(struct kernfs_open_file *of,
 	return 0;
 }
 
+static int rdtgroup_mbm_assign_cntrs_show(struct kernfs_open_file *of,
+					  struct seq_file *s, void *v)
+{
+	struct rdt_resource *r = of->kn->parent->priv;
+
+	seq_printf(s, "%d\n", r->mbm_assign_cntrs);
+
+	return 0;
+}
+
 #ifdef CONFIG_PROC_CPU_RESCTRL
 
 /*
@@ -1920,6 +1930,12 @@ static struct rftype res_common_files[] = {
 		.kf_ops		= &rdtgroup_kf_single_ops,
 		.seq_show	= rdtgroup_mbm_assign_show,
 	},
+	{
+		.name		= "mbm_assign_cntrs",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= rdtgroup_mbm_assign_cntrs_show,
+	},
 	{
 		.name		= "cpus",
 		.mode		= 0644,
-- 
2.34.1