x86/resctrl: Add support for the files of MON groups only

Files unique to monitoring groups have the RFTYPE_MON flag. When a new
monitoring group is created the resctrl files with flags RFTYPE_BASE
(files common to all resource groups) and RFTYPE_MON (files unique to
monitoring groups) are created to support interacting with the new
monitoring group.

A resource group can support both monitoring and control, also termed
a CTRL_MON resource group. CTRL_MON groups should get both monitoring
and control resctrl files but that is not the case. Only the
RFTYPE_BASE and RFTYPE_CTRL files are created for CTRL_MON groups.

Ensure that files with the RFTYPE_MON flag are created for CTRL_MON groups.
Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Peter Newman <peternewman@google.com>
Reviewed-by: Tan Shaopeng <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Tan Shaopeng <tan.shaopeng@jp.fujitsu.com>
Link: https://lore.kernel.org/r/20231017002308.134480-9-babu.moger@amd.com

arch/x86/kernel/cpu/resctrl/rdtgroup.c

@@ -2551,6 +2551,7 @@ static void schemata_list_destroy(void)
 static int rdt_get_tree(struct fs_context *fc)
 {
 	struct rdt_fs_context *ctx = rdt_fc2context(fc);
+	unsigned long flags = RFTYPE_CTRL_BASE;
 	struct rdt_domain *dom;
 	struct rdt_resource *r;
 	int ret;
@@ -2581,7 +2582,10 @@ static int rdt_get_tree(struct fs_context *fc)
 
 	closid_init();
 
-	ret = rdtgroup_add_files(rdtgroup_default.kn, RFTYPE_CTRL_BASE);
+	if (rdt_mon_capable)
+		flags |= RFTYPE_MON;
+
+	ret = rdtgroup_add_files(rdtgroup_default.kn, flags);
 	if (ret)
 		goto out_schemata_free;
 
@@ -3271,8 +3275,8 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
 			     enum rdt_group_type rtype, struct rdtgroup **r)
 {
 	struct rdtgroup *prdtgrp, *rdtgrp;
+	unsigned long files = 0;
 	struct kernfs_node *kn;
-	uint files = 0;
 	int ret;
 
 	prdtgrp = rdtgroup_kn_lock_live(parent_kn);
@@ -3324,10 +3328,13 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
 		goto out_destroy;
 	}
 
-	if (rtype == RDTCTRL_GROUP)
+	if (rtype == RDTCTRL_GROUP) {
 		files = RFTYPE_BASE | RFTYPE_CTRL;
-	else
+		if (rdt_mon_capable)
+			files |= RFTYPE_MON;
+	} else {
 		files = RFTYPE_BASE | RFTYPE_MON;
+	}
 
 	ret = rdtgroup_add_files(kn, files);
 	if (ret) {