x86,fs/resctrl: Add architectural event pointer

The resctrl file system layer passes the domain, RMID, and event id to the
architecture to fetch an event counter.

Fetching a telemetry event counter requires additional information that is
private to the architecture, for example, the offset into MMIO space from
where the counter should be read.

Add mon_evt::arch_priv that architecture can use for any private data related
to the event. The resctrl filesystem initializes mon_evt::arch_priv when the
architecture enables the event and passes it back to architecture when needing
to fetch an event counter.

Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
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>
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com

Author: aegl

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

@@ -918,15 +918,15 @@ static __init bool get_rdt_mon_resources(void)
 	bool ret = false;
 
 	if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) {
-		resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID, false, 0);
+		resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID, false, 0, NULL);
 		ret = true;
 	}
 	if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL)) {
-		resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID, false, 0);
+		resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID, false, 0, NULL);
 		ret = true;
 	}
 	if (rdt_cpu_has(X86_FEATURE_CQM_MBM_LOCAL)) {
-		resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID, false, 0);
+		resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID, false, 0, NULL);
 		ret = true;
 	}
 	if (rdt_cpu_has(X86_FEATURE_ABMC))

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

@@ -240,7 +240,7 @@ static u64 get_corrected_val(struct rdt_resource *r, struct rdt_l3_mon_domain *d
 
 int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain_hdr *hdr,
 			   u32 unused, u32 rmid, enum resctrl_event_id eventid,
-			   u64 *val, void *ignored)
+			   void *arch_priv, u64 *val, void *ignored)
 {
 	struct rdt_hw_l3_mon_domain *hw_dom;
 	struct rdt_l3_mon_domain *d;

fs/resctrl/internal.h

@@ -66,6 +66,9 @@ static inline struct rdt_fs_context *rdt_fc2context(struct fs_context *fc)
  * @binary_bits:	number of fixed-point binary bits from architecture,
  *			only valid if @is_floating_point is true
  * @enabled:		true if the event is enabled
+ * @arch_priv:		Architecture private data for this event.
+ *			The @arch_priv provided by the architecture via
+ *			resctrl_enable_mon_event().
  */
 struct mon_evt {
 	enum resctrl_event_id	evtid;
@@ -77,6 +80,7 @@ struct mon_evt {
 	bool			is_floating_point;
 	unsigned int		binary_bits;
 	bool			enabled;
+	void			*arch_priv;
 };
 
 extern struct mon_evt mon_event_all[QOS_NUM_EVENTS];

fs/resctrl/monitor.c

@@ -137,9 +137,11 @@ void __check_limbo(struct rdt_l3_mon_domain *d, bool force_free)
 	struct rmid_entry *entry;
 	u32 idx, cur_idx = 1;
 	void *arch_mon_ctx;
+	void *arch_priv;
 	bool rmid_dirty;
 	u64 val = 0;
 
+	arch_priv = mon_event_all[QOS_L3_OCCUP_EVENT_ID].arch_priv;
 	arch_mon_ctx = resctrl_arch_mon_ctx_alloc(r, QOS_L3_OCCUP_EVENT_ID);
 	if (IS_ERR(arch_mon_ctx)) {
 		pr_warn_ratelimited("Failed to allocate monitor context: %ld",
@@ -160,7 +162,7 @@ void __check_limbo(struct rdt_l3_mon_domain *d, bool force_free)
 
 		entry = __rmid_entry(idx);
 		if (resctrl_arch_rmid_read(r, &d->hdr, entry->closid, entry->rmid,
-					   QOS_L3_OCCUP_EVENT_ID, &val,
+					   QOS_L3_OCCUP_EVENT_ID, arch_priv, &val,
 					   arch_mon_ctx)) {
 			rmid_dirty = true;
 		} else {
@@ -456,7 +458,8 @@ static int __l3_mon_event_count(struct rdtgroup *rdtgrp, struct rmid_read *rr)
 						 rr->evt->evtid, &tval);
 	else
 		rr->err = resctrl_arch_rmid_read(rr->r, rr->hdr, closid, rmid,
-						 rr->evt->evtid, &tval, rr->arch_mon_ctx);
+						 rr->evt->evtid, rr->evt->arch_priv,
+						 &tval, rr->arch_mon_ctx);
 	if (rr->err)
 		return rr->err;
 
@@ -501,7 +504,8 @@ static int __l3_mon_event_count_sum(struct rdtgroup *rdtgrp, struct rmid_read *r
 		if (d->ci_id != rr->ci->id)
 			continue;
 		err = resctrl_arch_rmid_read(rr->r, &d->hdr, closid, rmid,
-					     rr->evt->evtid, &tval, rr->arch_mon_ctx);
+					     rr->evt->evtid, rr->evt->arch_priv,
+					     &tval, rr->arch_mon_ctx);
 		if (!err) {
 			rr->val += tval;
 			ret = 0;
@@ -993,7 +997,8 @@ struct mon_evt mon_event_all[QOS_NUM_EVENTS] = {
 	MON_EVENT(PMT_EVENT_UOPS_RETIRED,		"uops_retired",		RDT_RESOURCE_PERF_PKG,	false),
 };
 
-void resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu, unsigned int binary_bits)
+void resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu,
+			      unsigned int binary_bits, void *arch_priv)
 {
 	if (WARN_ON_ONCE(eventid < QOS_FIRST_EVENT || eventid >= QOS_NUM_EVENTS ||
 			 binary_bits > MAX_BINARY_BITS))
@@ -1009,6 +1014,7 @@ void resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu, unsig
 
 	mon_event_all[eventid].any_cpu = any_cpu;
 	mon_event_all[eventid].binary_bits = binary_bits;
+	mon_event_all[eventid].arch_priv = arch_priv;
 	mon_event_all[eventid].enabled = true;
 }
 

include/linux/resctrl.h

@@ -415,7 +415,7 @@ u32 resctrl_arch_system_num_rmid_idx(void);
 int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
 
 void resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu,
-			      unsigned int binary_bits);
+			      unsigned int binary_bits, void *arch_priv);
 
 bool resctrl_is_mon_event_enabled(enum resctrl_event_id eventid);
 
@@ -532,6 +532,9 @@ void resctrl_arch_pre_mount(void);
  *			only.
  * @rmid:		rmid of the counter to read.
  * @eventid:		eventid to read, e.g. L3 occupancy.
+ * @arch_priv:		Architecture private data for this event.
+ *			The @arch_priv provided by the architecture via
+ *			resctrl_enable_mon_event().
  * @val:		result of the counter read in bytes.
  * @arch_mon_ctx:	An architecture specific value from
  *			resctrl_arch_mon_ctx_alloc(), for MPAM this identifies
@@ -549,7 +552,7 @@ void resctrl_arch_pre_mount(void);
  */
 int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain_hdr *hdr,
 			   u32 closid, u32 rmid, enum resctrl_event_id eventid,
-			   u64 *val, void *arch_mon_ctx);
+			   void *arch_priv, u64 *val, void *arch_mon_ctx);
 
 /**
  * resctrl_arch_rmid_read_context_check()  - warn about invalid contexts