[PATCH 16/21] x86/intel_rdt/cqm: Add mount,umount support

[Vikas Shivappa]

Add monitoring support during mount and unmount. Since root directory is
a "ctrl_mon" directory which can control and monitor resources create
the "mon_groups" directory which can hold monitor groups and a
"mon_data" directory which would hold all monitoring data like the rest
of resource groups.

The mount succeeds if either of monitoring or control/allocation is
enabled. If only monitoring is enabled user can still create monitor
groups under the "/sys/fs/resctrl/mon_groups/" and any mkdir under root
would fail. If only control/allocation is enabled all of the monitoring
related directories/files would not exist and resctrl would work in
legacy mode.

Signed-off-by: Vikas Shivappa <vikas.shivappa@xxxxxxxxxxxxxxx>
---
 arch/x86/kernel/cpu/intel_rdt.h          |  5 +++
 arch/x86/kernel/cpu/intel_rdt_monitor.c  |  3 ++
 arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 67 +++++++++++++++++++++++++++++---
 3 files changed, 70 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel_rdt.h b/arch/x86/kernel/cpu/intel_rdt.h
index 631d58e..ea7a86f 100644
--- a/arch/x86/kernel/cpu/intel_rdt.h
+++ b/arch/x86/kernel/cpu/intel_rdt.h
@@ -22,6 +22,9 @@
 
 #define RMID_VAL_ERROR		(1ULL << 63)
 #define RMID_VAL_UNAVAIL	(1ULL << 62)
+
+DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
+
 /**
  * struct mon_evt - Entry in the event list of a resource
  * @evtid:		event id
@@ -59,6 +62,8 @@ struct rmid_read {
 extern int rdt_mon_features;
 
 DECLARE_PER_CPU_READ_MOSTLY(int, cpu_rmid);
+DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
+
 
 enum rdt_group_type {
 	RDTCTRL_GROUP = 0,
diff --git a/arch/x86/kernel/cpu/intel_rdt_monitor.c b/arch/x86/kernel/cpu/intel_rdt_monitor.c
index cc252eb..a7247ca 100644
--- a/arch/x86/kernel/cpu/intel_rdt_monitor.c
+++ b/arch/x86/kernel/cpu/intel_rdt_monitor.c
@@ -76,6 +76,9 @@ struct rmid_entry {
 unsigned int intel_cqm_threshold;
 
 DEFINE_PER_CPU_READ_MOSTLY(int, cpu_rmid);
+
+DEFINE_STATIC_KEY_FALSE(rdt_mon_enable_key);
+
 static inline struct rmid_entry *__rmid_entry(u32 rmid)
 {
 	struct rmid_entry *entry;
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index 6131508..2384c07 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -35,6 +35,7 @@
 #include <asm/intel_rdt_sched.h>
 #include "intel_rdt.h"
 
+DEFINE_STATIC_KEY_FALSE(rdt_enable_key);
 DEFINE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
 struct kernfs_root *rdt_root;
 struct rdtgroup rdtgroup_default;
@@ -43,6 +44,12 @@
 /* Kernel fs node for "info" directory under root */
 static struct kernfs_node *kn_info;
 
+/* Kernel fs node for "mon_groups" directory under root */
+static struct kernfs_node *kn_mongrp;
+
+/* Kernel fs node for "mon_data" directory under root */
+static struct kernfs_node *kn_mondata;
+
 /*
  * Trivial allocator for CLOSIDs. Since h/w only supports a small number,
  * we can keep a bitmap of free CLOSIDs in a single integer.
@@ -1078,6 +1085,9 @@ void rdtgroup_kn_unlock(struct kernfs_node *kn)
 	}
 }
 
+static int mkdir_mondata_all(struct kernfs_node *parent_kn, struct rdtgroup *pr,
+			     struct kernfs_node **mon_data_kn);
+
 static struct dentry *rdt_mount(struct file_system_type *fs_type,
 				int flags, const char *unused_dev_name,
 				void *data)
@@ -1089,7 +1099,7 @@ static struct dentry *rdt_mount(struct file_system_type *fs_type,
 	/*
 	 * resctrl file system can only be mounted once.
 	 */
-	if (static_branch_unlikely(&rdt_alloc_enable_key)) {
+	if (static_branch_unlikely(&rdt_enable_key)) {
 		dentry = ERR_PTR(-EBUSY);
 		goto out;
 	}
@@ -1108,15 +1118,47 @@ static struct dentry *rdt_mount(struct file_system_type *fs_type,
 		goto out_cdp;
 	}
 
+	if (rdt_mon_features) {
+		ret = mongroup_create_dir(rdtgroup_default.kn,
+					  NULL, "mon_groups",
+					  &kn_mongrp);
+		if (ret) {
+			dentry = ERR_PTR(ret);
+			goto out_info;
+		}
+		kernfs_get(kn_mongrp);
+
+		ret = mkdir_mondata_all(rdtgroup_default.kn,
+					&rdtgroup_default, &kn_mondata);
+		if (ret) {
+			dentry = ERR_PTR(ret);
+			goto out_mongrp;
+		}
+		kernfs_get(kn_mondata);
+		rdtgroup_default.mon_data_kn = kn_mondata;
+	}
+
 	dentry = kernfs_mount(fs_type, flags, rdt_root,
 			      RDTGROUP_SUPER_MAGIC, NULL);
 	if (IS_ERR(dentry))
-		goto out_destroy;
+		goto out_mondata;
 
-	static_branch_enable(&rdt_alloc_enable_key);
+	if (rdt_alloc_enabled)
+		static_branch_enable(&rdt_alloc_enable_key);
+	if (rdt_mon_features)
+		static_branch_enable(&rdt_mon_enable_key);
+
+	if (rdt_alloc_enabled || rdt_mon_features)
+		static_branch_enable(&rdt_enable_key);
 	goto out;
 
-out_destroy:
+out_mondata:
+	if (rdt_mon_features)
+		kernfs_remove(kn_mondata);
+out_mongrp:
+	if (rdt_mon_features)
+		kernfs_remove(kn_mongrp);
+out_info:
 	kernfs_remove(kn_info);
 out_cdp:
 	cdp_disable();
@@ -1219,12 +1261,21 @@ static void rdt_move_group_tasks(struct rdtgroup *from, struct rdtgroup *to,
  */
 static void rmdir_all_sub(void)
 {
-	struct rdtgroup *rdtgrp, *tmp;
+	struct rdtgroup *rdtgrp, *tmp, *sentry, *stmp;
+	struct list_head *llist;
 
 	/* Move all tasks to the default resource group */
 	rdt_move_group_tasks(NULL, &rdtgroup_default, NULL);
 
 	list_for_each_entry_safe(rdtgrp, tmp, &rdt_all_groups, rdtgroup_list) {
+		/* Free any child rmids */
+		llist = &rdtgrp->crdtgrp_list;
+		list_for_each_entry_safe(sentry, stmp, llist, crdtgrp_list) {
+			free_rmid(sentry->rmid);
+			list_del(&sentry->crdtgrp_list);
+			kfree(sentry);
+		}
+
 		/* Remove each rdtgroup other than root */
 		if (rdtgrp == &rdtgroup_default)
 			continue;
@@ -1237,6 +1288,8 @@ static void rmdir_all_sub(void)
 		cpumask_or(&rdtgroup_default.cpu_mask,
 			   &rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);
 
+		free_rmid(rdtgrp->rmid);
+
 		kernfs_remove(rdtgrp->kn);
 		list_del(&rdtgrp->rdtgroup_list);
 		kfree(rdtgrp);
@@ -1247,6 +1300,8 @@ static void rmdir_all_sub(void)
 	put_online_cpus();
 
 	kernfs_remove(kn_info);
+	kernfs_remove(kn_mongrp);
+	kernfs_remove(kn_mondata);
 }
 
 static void rdt_kill_sb(struct super_block *sb)
@@ -1261,6 +1316,8 @@ static void rdt_kill_sb(struct super_block *sb)
 	cdp_disable();
 	rmdir_all_sub();
 	static_branch_disable(&rdt_alloc_enable_key);
+	static_branch_disable(&rdt_mon_enable_key);
+	static_branch_disable(&rdt_enable_key);
 	kernfs_kill_sb(sb);
 	mutex_unlock(&rdtgroup_mutex);
 }
-- 
1.9.1