x86/resctrl: Move alloc/mon static keys into helpers

resctrl enables three static keys depending on the features it has enabled.
Another architecture's context switch code may look different, any static keys
that control it should be buried behind helpers.

Move the alloc/mon logic into arch-specific helpers as a preparatory step for
making the rdt_enable_key's status something the arch code decides.

This means other architectures don't have to mirror the static keys.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Link: https://lore.kernel.org/r/20240213184438.16675-18-james.morse@arm.com
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>

Author: James Morse

arch/x86/include/asm/resctrl.h

@@ -42,6 +42,26 @@ DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
 DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
 DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
 
+static inline void resctrl_arch_enable_alloc(void)
+{
+	static_branch_enable_cpuslocked(&rdt_alloc_enable_key);
+}
+
+static inline void resctrl_arch_disable_alloc(void)
+{
+	static_branch_disable_cpuslocked(&rdt_alloc_enable_key);
+}
+
+static inline void resctrl_arch_enable_mon(void)
+{
+	static_branch_enable_cpuslocked(&rdt_mon_enable_key);
+}
+
+static inline void resctrl_arch_disable_mon(void)
+{
+	static_branch_disable_cpuslocked(&rdt_mon_enable_key);
+}
+
 /*
  * __resctrl_sched_in() - Writes the task's CLOSid/RMID to IA32_PQR_MSR
  *

arch/x86/kernel/cpu/resctrl/internal.h

@@ -94,9 +94,6 @@ static inline struct rdt_fs_context *rdt_fc2context(struct fs_context *fc)
 	return container_of(kfc, struct rdt_fs_context, kfc);
 }
 
-DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
-DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
-
 /**
  * struct mon_evt - Entry in the event list of a resource
  * @evtid:		event id
@@ -452,8 +449,6 @@ extern struct mutex rdtgroup_mutex;
 
 extern struct rdt_hw_resource rdt_resources_all[];
 extern struct rdtgroup rdtgroup_default;
-DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
-
 extern struct dentry *debugfs_resctrl;
 
 enum resctrl_res_level {

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

@@ -2668,9 +2668,9 @@ static int rdt_get_tree(struct fs_context *fc)
 		goto out_psl;
 
 	if (rdt_alloc_capable)
-		static_branch_enable_cpuslocked(&rdt_alloc_enable_key);
+		resctrl_arch_enable_alloc();
 	if (rdt_mon_capable)
-		static_branch_enable_cpuslocked(&rdt_mon_enable_key);
+		resctrl_arch_enable_mon();
 
 	if (rdt_alloc_capable || rdt_mon_capable) {
 		static_branch_enable_cpuslocked(&rdt_enable_key);
@@ -2946,8 +2946,8 @@ static void rdt_kill_sb(struct super_block *sb)
 	rdtgroup_default.mode = RDT_MODE_SHAREABLE;
 	schemata_list_destroy();
 	rdtgroup_destroy_root();
-	static_branch_disable_cpuslocked(&rdt_alloc_enable_key);
-	static_branch_disable_cpuslocked(&rdt_mon_enable_key);
+	resctrl_arch_disable_alloc();
+	resctrl_arch_disable_mon();
 	static_branch_disable_cpuslocked(&rdt_enable_key);
 	resctrl_mounted = false;
 	kernfs_kill_sb(sb);