[PATCH v6 08/22] x86/resctrl: Introduce interface to display number of monitoring counters

[Babu Moger <babu.moger@amd.com>]

The ABMC feature provides an option to the user to assign a hardware
counter to an RMID and monitor the bandwidth as long as the counter is
assigned. Number of assignments depend on number of monitoring counters
available.

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

Signed-off-by: Babu Moger <babu.moger@amd.com>
---
v6: No changes.

v5: Changed the display name from num_cntrs to num_mbm_cntrs.
    Updated the commit message.
    Moved the patch after mbm_mode is introduced.

v4: Changed the counter name to num_cntrs. And few text changes.

v3: Changed the field name to mbm_assign_cntrs.

v2: Changed the field name to mbm_assignable_counters from abmc_counte
---
 Documentation/arch/x86/resctrl.rst     |  3 +++
 arch/x86/kernel/cpu/resctrl/monitor.c  |  2 ++
 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 d4ec605b200a..fe9f10766c4f 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -291,6 +291,9 @@ with the following files:
 		as long as there are enough RMID counters available to support number
 		of monitoring groups.
 
+"num_mbm_cntrs":
+	The number of monitoring counters available for assignment.
+
 "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 5e8706ab6361..83329cefebf7 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -1242,6 +1242,8 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 			r->mon.num_mbm_cntrs = (ebx & 0xFFFF) + 1;
 			if (WARN_ON(r->mon.num_mbm_cntrs > 64))
 				r->mon.num_mbm_cntrs = 64;
+
+			resctrl_file_fflags_init("num_mbm_cntrs", RFTYPE_MON_INFO);
 		}
 	}
 
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index d8f85b20ab8f..ab4fab3b7cf1 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -865,6 +865,16 @@ static int rdtgroup_mbm_mode_show(struct kernfs_open_file *of,
 	return 0;
 }
 
+static int rdtgroup_num_mbm_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->mon.num_mbm_cntrs);
+
+	return 0;
+}
+
 #ifdef CONFIG_PROC_CPU_RESCTRL
 
 /*
@@ -1936,6 +1946,12 @@ static struct rftype res_common_files[] = {
 		.seq_show	= rdtgroup_cpus_show,
 		.fflags		= RFTYPE_BASE,
 	},
+	{
+		.name		= "num_mbm_cntrs",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= rdtgroup_num_mbm_cntrs_show,
+	},
 	{
 		.name		= "cpus_list",
 		.mode		= 0644,
-- 
2.34.1