x86/resctrl: Introduce "-o debug" mount option

Add "-o debug" option to mount resctrl filesystem in debug mode.  When
in debug mode resctrl displays files that have the new RFTYPE_DEBUG flag
to help resctrl debugging.

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: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Tan Shaopeng <tan.shaopeng@jp.fujitsu.com>
Link: https://lore.kernel.org/r/20231017002308.134480-7-babu.moger@amd.com

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index 178ab1d8f7475279f105d77e28899a0978e4b4a8..68f11611f3416cef47e06146bdecc84570d0b50b 100644 (file)
--- 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 ba4611111212f4a20d94f77959d6f7d02e183aee..b816b902b5c05849b703572a98bee17bba0d2ba2 100644 (file)
--- 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)
@@ -248,6 +249,7 @@ 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 55da93b5ca53a1fb767727f5272125c7a15eb40d..84e0f45578dd5f1de9ddaa443bf9cec258ccede3 100644 (file)
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -59,6 +59,8 @@ static void rdtgroup_destroy_root(void);
 
 struct dentry *debugfs_resctrl;
 
+static bool resctrl_debug;
+
 void rdt_last_cmd_clear(void)
 {
        lockdep_assert_held(&rdtgroup_mutex);
@@ -1892,6 +1894,9 @@ 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);
@@ -2395,6 +2400,8 @@ static void rdt_disable_ctx(void)
        resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, false);
        resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, false);
        set_mba_sc(false);
+
+       resctrl_debug = false;
 }
 
 static int rdt_enable_ctx(struct rdt_fs_context *ctx)
@@ -2419,6 +2426,9 @@ static int rdt_enable_ctx(struct rdt_fs_context *ctx)
                        goto out_cdpl3;
        }
 
+       if (ctx->enable_debug)
+               resctrl_debug = true;
+
        return 0;
 
 out_cdpl3:
@@ -2623,6 +2633,7 @@ enum rdt_param {
        Opt_cdp,
        Opt_cdpl2,
        Opt_mba_mbps,
+       Opt_debug,
        nr__rdt_params
 };
 
@@ -2630,6 +2641,7 @@ 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),
        {}
 };
 
@@ -2655,6 +2667,9 @@ 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;
@@ -3723,6 +3738,9 @@ 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;
 }