x86/resctrl: Add resctrl_arch_is_evt_configurable() to abstract BMEC

When BMEC is supported the resctrl event can be configured in a number of
ways. This depends on architecture support. rdt_get_mon_l3_config() modifies
the struct mon_evt and calls resctrl_file_fflags_init() to create the files
that allow the configuration.

Splitting this into separate architecture and filesystem parts would require
the struct mon_evt and resctrl_file_fflags_init() to be exposed.

Instead, add resctrl_arch_is_evt_configurable(), and use this from
resctrl_mon_resource_init() to initialise struct mon_evt and call
resctrl_file_fflags_init().

resctrl_arch_is_evt_configurable() calls rdt_cpu_has() so it doesn't obviously
benefit from being inlined. Putting it in core.c will allow rdt_cpu_has() to
eventually become static.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Amit Singh Tomar <amitsinght@marvell.com> # arm64
Tested-by: Shanker Donthineni <sdonthineni@nvidia.com> # arm64
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20250311183715.16445-20-james.morse@arm.com

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

@@ -830,6 +830,21 @@ bool __init rdt_cpu_has(int flag)
 	return ret;
 }
 
+__init bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt)
+{
+	if (!rdt_cpu_has(X86_FEATURE_BMEC))
+		return false;
+
+	switch (evt) {
+	case QOS_L3_MBM_TOTAL_EVENT_ID:
+		return rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL);
+	case QOS_L3_MBM_LOCAL_EVENT_ID:
+		return rdt_cpu_has(X86_FEATURE_CQM_MBM_LOCAL);
+	default:
+		return false;
+	}
+}
+
 static __init bool get_mem_config(void)
 {
 	struct rdt_hw_resource *hw_res = &rdt_resources_all[RDT_RESOURCE_MBA];

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

@@ -1202,6 +1202,17 @@ int __init resctrl_mon_resource_init(void)
 
 	l3_mon_evt_init(r);
 
+	if (resctrl_arch_is_evt_configurable(QOS_L3_MBM_TOTAL_EVENT_ID)) {
+		mbm_total_event.configurable = true;
+		resctrl_file_fflags_init("mbm_total_bytes_config",
+					 RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
+	}
+	if (resctrl_arch_is_evt_configurable(QOS_L3_MBM_LOCAL_EVENT_ID)) {
+		mbm_local_event.configurable = true;
+		resctrl_file_fflags_init("mbm_local_bytes_config",
+					 RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
+	}
+
 	return 0;
 }
 
@@ -1245,17 +1256,6 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 		/* Detect list of bandwidth sources that can be tracked */
 		cpuid_count(0x80000020, 3, &eax, &ebx, &ecx, &edx);
 		hw_res->mbm_cfg_mask = ecx & MAX_EVT_CONFIG_BITS;
-
-		if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL)) {
-			mbm_total_event.configurable = true;
-			resctrl_file_fflags_init("mbm_total_bytes_config",
-						 RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
-		}
-		if (rdt_cpu_has(X86_FEATURE_CQM_MBM_LOCAL)) {
-			mbm_local_event.configurable = true;
-			resctrl_file_fflags_init("mbm_local_bytes_config",
-						 RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
-		}
 	}
 
 	r->mon_capable = true;

include/linux/resctrl.h

@@ -309,6 +309,8 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *r);
 u32 resctrl_arch_system_num_rmid_idx(void);
 int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
 
+__init bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt);
+
 /*
  * Update the ctrl_val and apply this config right now.
  * Must be called on one of the domain's CPUs.