[PATCH v6 7/8] x86/resctrl: Introduce "-o debug" mount option

[Babu Moger <babu.moger@xxxxxxx>]

Add "-o debug" option to mount resctrl filesystem in debug mode. This
option is used for adding extra files to help resctrl debugging.

Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
 Documentation/arch/x86/resctrl.rst     |    5 ++++-
 arch/x86/kernel/cpu/resctrl/internal.h |    2 ++
 arch/x86/kernel/cpu/resctrl/rdtgroup.c |   20 ++++++++++++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index af234681756e..5a2346d2c561 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -35,7 +35,7 @@ about the feature from resctrl's info directory.
 
 To use the feature mount the file system::
 
- # mount -t resctrl resctrl [-o cdp[,cdpl2][,mba_MBps]] /sys/fs/resctrl
+ # mount -t resctrl resctrl [-o cdp[,cdpl2][,mba_MBps][,debug]] /sys/fs/resctrl
 
 mount options are:
 
@@ -46,6 +46,9 @@ mount options are:
 "mba_MBps":
 	Enable the MBA Software Controller(mba_sc) to specify MBA
 	bandwidth in MBps
+"debug":
+	Make debug files accessible. Available debug files are annotated with
+	"Available only with debug option".
 
 L2 and L3 CDP are controlled separately.
 
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 885b656d1088..5bc18accb887 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -59,6 +59,7 @@ struct rdt_fs_context {
 	bool				enable_cdpl2;
 	bool				enable_cdpl3;
 	bool				enable_mba_mbps;
+	bool				enable_debug;
 };
 
 static inline struct rdt_fs_context *rdt_fc2context(struct fs_context *fc)
@@ -296,6 +297,7 @@ struct rdtgroup {
 #define RFTYPE_TOP			BIT(6)
 #define RFTYPE_RES_CACHE		BIT(8)
 #define RFTYPE_RES_MB			BIT(9)
+#define RFTYPE_DEBUG			BIT(10)
 #define RFTYPE_CTRL_INFO		(RFTYPE_INFO | RFTYPE_CTRL)
 #define RFTYPE_MON_INFO			(RFTYPE_INFO | RFTYPE_MON)
 #define RFTYPE_TOP_INFO			(RFTYPE_INFO | RFTYPE_TOP)
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index e0570bce76a2..058c1dedb2d7 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -56,6 +56,8 @@ static char last_cmd_status_buf[512];
 
 struct dentry *debugfs_resctrl;
 
+static bool resctrl_debug;
+
 void rdt_last_cmd_clear(void)
 {
 	lockdep_assert_held(&rdtgroup_mutex);
@@ -1871,6 +1873,9 @@ static int rdtgroup_add_files(struct kernfs_node *kn, unsigned long fflags)
 
 	lockdep_assert_held(&rdtgroup_mutex);
 
+	if (resctrl_debug)
+		fflags |= RFTYPE_DEBUG;
+
 	for (rft = rfts; rft < rfts + len; rft++) {
 		if (rft->fflags && ((fflags & rft->fflags) == rft->fflags)) {
 			ret = rdtgroup_add_file(kn, rft);
@@ -2399,6 +2404,9 @@ static int rdt_enable_ctx(struct rdt_fs_context *ctx)
 			goto out_cdpl3;
 	}
 
+	if (ctx->enable_debug)
+		resctrl_debug = true;
+
 	return 0;
 
 out_cdpl3:
@@ -2591,6 +2599,8 @@ static int rdt_get_tree(struct fs_context *fc)
 out_schemata_free:
 	schemata_list_destroy();
 out_ctx:
+	if (ctx->enable_debug)
+		resctrl_debug = false;
 	if (ctx->enable_mba_mbps)
 		set_mba_sc(false);
 	cdp_disable_all();
@@ -2608,6 +2618,7 @@ enum rdt_param {
 	Opt_cdp,
 	Opt_cdpl2,
 	Opt_mba_mbps,
+	Opt_debug,
 	nr__rdt_params
 };
 
@@ -2615,6 +2626,7 @@ static const struct fs_parameter_spec rdt_fs_parameters[] = {
 	fsparam_flag("cdp",		Opt_cdp),
 	fsparam_flag("cdpl2",		Opt_cdpl2),
 	fsparam_flag("mba_MBps",	Opt_mba_mbps),
+	fsparam_flag("debug",		Opt_debug),
 	{}
 };
 
@@ -2640,6 +2652,9 @@ static int rdt_parse_param(struct fs_context *fc, struct fs_parameter *param)
 			return -EINVAL;
 		ctx->enable_mba_mbps = true;
 		return 0;
+	case Opt_debug:
+		ctx->enable_debug = true;
+		return 0;
 	}
 
 	return -EINVAL;
@@ -2829,6 +2844,8 @@ static void rdt_kill_sb(struct super_block *sb)
 
 	set_mba_sc(false);
 
+	resctrl_debug = false;
+
 	/*Put everything back to default values. */
 	for_each_alloc_capable_rdt_resource(r)
 		reset_all_ctrls(r);
@@ -3710,6 +3727,9 @@ static int rdtgroup_show_options(struct seq_file *seq, struct kernfs_root *kf)
 	if (is_mba_sc(&rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl))
 		seq_puts(seq, ",mba_MBps");
 
+	if (resctrl_debug)
+		seq_puts(seq, ",debug");
+
 	return 0;
 }