x86/resctrl: Prepare for per-CTRL_MON group mba_MBps control

Resctrl uses local memory bandwidth event as input to the feedback loop when
the mba_MBps mount option is used. This means that this mount option cannot be
used on systems that only support monitoring of total bandwidth.

Prepare to allow users to choose the input event independently for each
CTRL_MON group by adding a global variable "mba_mbps_default_event" used to
set the default event for each CTRL_MON group, and a new field
"mba_mbps_event" in struct rdtgroup to track which event is used for each
CTRL_MON group.

Notes:

1) Both of these are only used when the user mounts the filesystem with the
   "mba_MBps" option.
2) Only check for support of local bandwidth event when initializing
   mba_mbps_default_event. Support for total bandwidth event can be added
   after other routines in resctrl have been updated to handle total bandwidth
   event.

  [ bp: Move mba_mbps_default_event extern into the arch header. ]

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20241206163148.83828-3-tony.luck@intel.com

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index f3ee5859b69de6a064f2659b80d9aded99608795..94bf559966d624650dfc26936dda37c09992892a 100644 (file)
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -963,6 +963,9 @@ static __init bool get_rdt_mon_resources(void)
        if (!rdt_mon_features)
                return false;
 
+       if (is_mbm_local_enabled())
+               mba_mbps_default_event = QOS_L3_MBM_LOCAL_EVENT_ID;
+
        return !rdt_get_mon_l3_config(r);
 }
 

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index faaff9d641029c61c099bf5e705d6c3b1ed3cc2c..542d01c055aa0f6d711ba7ce3d0acc8ebb5eb686 100644 (file)
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -283,6 +283,7 @@ struct pseudo_lock_region {
  *                             monitor only or ctrl_mon group
  * @mon:                       mongroup related data
  * @mode:                      mode of resource group
+ * @mba_mbps_event:            input monitoring event id when mba_sc is enabled
  * @plr:                       pseudo-locked region
  */
 struct rdtgroup {
@@ -295,6 +296,7 @@ struct rdtgroup {
        enum rdt_group_type             type;
        struct mongroup                 mon;
        enum rdtgrp_mode                mode;
+       enum resctrl_event_id           mba_mbps_event;
        struct pseudo_lock_region       *plr;
 };
 
@@ -508,6 +510,7 @@ extern struct mutex rdtgroup_mutex;
 extern struct rdt_hw_resource rdt_resources_all[];
 extern struct rdtgroup rdtgroup_default;
 extern struct dentry *debugfs_resctrl;
+extern enum resctrl_event_id mba_mbps_default_event;
 
 enum resctrl_res_level {
        RDT_RESOURCE_L3,
@@ -651,5 +654,4 @@ void resctrl_file_fflags_init(const char *config, unsigned long fflags);
 void rdt_staged_configs_clear(void);
 bool closid_allocated(unsigned int closid);
 int resctrl_find_cleanest_closid(void);
-
 #endif /* _ASM_X86_RESCTRL_INTERNAL_H */

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index d333570e893d34ffd2f98ae686a1bcfa79db8146..8a52b25ce26b86c476c5bf95ec8619d8a1d81317 100644 (file)
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -65,6 +65,15 @@ static void rdtgroup_destroy_root(void);
 
 struct dentry *debugfs_resctrl;
 
+/*
+ * Memory bandwidth monitoring event to use for the default CTRL_MON group
+ * and each new CTRL_MON group created by the user.  Only relevant when
+ * the filesystem is mounted with the "mba_MBps" option so it does not
+ * matter that it remains uninitialized on systems that do not support
+ * the "mba_MBps" option.
+ */
+enum resctrl_event_id mba_mbps_default_event;
+
 static bool resctrl_debug;
 
 void rdt_last_cmd_clear(void)
@@ -2353,6 +2362,8 @@ static int set_mba_sc(bool mba_sc)
 
        r->membw.mba_sc = mba_sc;
 
+       rdtgroup_default.mba_mbps_event = mba_mbps_default_event;
+
        list_for_each_entry(d, &r->ctrl_domains, hdr.list) {
                for (i = 0; i < num_closid; i++)
                        d->mbps_val[i] = MBA_MAX_MBPS;
@@ -3611,6 +3622,8 @@ static int rdtgroup_mkdir_ctrl_mon(struct kernfs_node *parent_kn,
                        rdt_last_cmd_puts("kernfs subdir error\n");
                        goto out_del_list;
                }
+               if (is_mba_sc(NULL))
+                       rdtgrp->mba_mbps_event = mba_mbps_default_event;
        }
 
        goto out_unlock;