1 /*
2  * Resource Director Technology(RDT)
3  * - Monitoring code
4  *
5  * Copyright (C) 2017 Intel Corporation
6  *
7  * Author:
8  *    Vikas Shivappa <vikas.shivappa@intel.com>
9  *
10  * This replaces the cqm.c based on perf but we reuse a lot of
11  * code and datastructures originally from Peter Zijlstra and Matt Fleming.
12  *
13  * This program is free software; you can redistribute it and/or modify it
14  * under the terms and conditions of the GNU General Public License,
15  * version 2, as published by the Free Software Foundation.
16  *
17  * This program is distributed in the hope it will be useful, but WITHOUT
18  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
19  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
20  * more details.
21  *
22  * More information about RDT be found in the Intel (R) x86 Architecture
23  * Software Developer Manual June 2016, volume 3, section 17.17.
24  */
25 
26 #include <linux/module.h>
27 #include <linux/slab.h>
28 #include <asm/cpu_device_id.h>
29 #include "intel_rdt.h"
30 
31 #define MSR_IA32_QM_CTR		0x0c8e
32 #define MSR_IA32_QM_EVTSEL		0x0c8d
33 
34 struct rmid_entry {
35 	u32				rmid;
36 	int				busy;
37 	struct list_head		list;
38 };
39 
40 /**
41  * @rmid_free_lru    A least recently used list of free RMIDs
42  *     These RMIDs are guaranteed to have an occupancy less than the
43  *     threshold occupancy
44  */
45 static LIST_HEAD(rmid_free_lru);
46 
47 /**
48  * @rmid_limbo_count     count of currently unused but (potentially)
49  *     dirty RMIDs.
50  *     This counts RMIDs that no one is currently using but that
51  *     may have a occupancy value > intel_cqm_threshold. User can change
52  *     the threshold occupancy value.
53  */
54 static unsigned int rmid_limbo_count;
55 
56 /**
57  * @rmid_entry - The entry in the limbo and free lists.
58  */
59 static struct rmid_entry	*rmid_ptrs;
60 
61 /*
62  * Global boolean for rdt_monitor which is true if any
63  * resource monitoring is enabled.
64  */
65 bool rdt_mon_capable;
66 
67 /*
68  * Global to indicate which monitoring events are enabled.
69  */
70 unsigned int rdt_mon_features;
71 
72 /*
73  * This is the threshold cache occupancy at which we will consider an
74  * RMID available for re-allocation.
75  */
76 unsigned int intel_cqm_threshold;
77 
__rmid_entry(u32 rmid)78 static inline struct rmid_entry *__rmid_entry(u32 rmid)
79 {
80 	struct rmid_entry *entry;
81 
82 	entry = &rmid_ptrs[rmid];
83 	WARN_ON(entry->rmid != rmid);
84 
85 	return entry;
86 }
87 
__rmid_read(u32 rmid,u32 eventid)88 static u64 __rmid_read(u32 rmid, u32 eventid)
89 {
90 	u64 val;
91 
92 	/*
93 	 * As per the SDM, when IA32_QM_EVTSEL.EvtID (bits 7:0) is configured
94 	 * with a valid event code for supported resource type and the bits
95 	 * IA32_QM_EVTSEL.RMID (bits 41:32) are configured with valid RMID,
96 	 * IA32_QM_CTR.data (bits 61:0) reports the monitored data.
97 	 * IA32_QM_CTR.Error (bit 63) and IA32_QM_CTR.Unavailable (bit 62)
98 	 * are error bits.
99 	 */
100 	wrmsr(MSR_IA32_QM_EVTSEL, eventid, rmid);
101 	rdmsrl(MSR_IA32_QM_CTR, val);
102 
103 	return val;
104 }
105 
rmid_dirty(struct rmid_entry * entry)106 static bool rmid_dirty(struct rmid_entry *entry)
107 {
108 	u64 val = __rmid_read(entry->rmid, QOS_L3_OCCUP_EVENT_ID);
109 
110 	return val >= intel_cqm_threshold;
111 }
112 
113 /*
114  * Check the RMIDs that are marked as busy for this domain. If the
115  * reported LLC occupancy is below the threshold clear the busy bit and
116  * decrement the count. If the busy count gets to zero on an RMID, we
117  * free the RMID
118  */
__check_limbo(struct rdt_domain * d,bool force_free)119 void __check_limbo(struct rdt_domain *d, bool force_free)
120 {
121 	struct rmid_entry *entry;
122 	struct rdt_resource *r;
123 	u32 crmid = 1, nrmid;
124 
125 	r = &rdt_resources_all[RDT_RESOURCE_L3];
126 
127 	/*
128 	 * Skip RMID 0 and start from RMID 1 and check all the RMIDs that
129 	 * are marked as busy for occupancy < threshold. If the occupancy
130 	 * is less than the threshold decrement the busy counter of the
131 	 * RMID and move it to the free list when the counter reaches 0.
132 	 */
133 	for (;;) {
134 		nrmid = find_next_bit(d->rmid_busy_llc, r->num_rmid, crmid);
135 		if (nrmid >= r->num_rmid)
136 			break;
137 
138 		entry = __rmid_entry(nrmid);
139 		if (force_free || !rmid_dirty(entry)) {
140 			clear_bit(entry->rmid, d->rmid_busy_llc);
141 			if (!--entry->busy) {
142 				rmid_limbo_count--;
143 				list_add_tail(&entry->list, &rmid_free_lru);
144 			}
145 		}
146 		crmid = nrmid + 1;
147 	}
148 }
149 
has_busy_rmid(struct rdt_resource * r,struct rdt_domain * d)150 bool has_busy_rmid(struct rdt_resource *r, struct rdt_domain *d)
151 {
152 	return find_first_bit(d->rmid_busy_llc, r->num_rmid) != r->num_rmid;
153 }
154 
155 /*
156  * As of now the RMIDs allocation is global.
157  * However we keep track of which packages the RMIDs
158  * are used to optimize the limbo list management.
159  */
alloc_rmid(void)160 int alloc_rmid(void)
161 {
162 	struct rmid_entry *entry;
163 
164 	lockdep_assert_held(&rdtgroup_mutex);
165 
166 	if (list_empty(&rmid_free_lru))
167 		return rmid_limbo_count ? -EBUSY : -ENOSPC;
168 
169 	entry = list_first_entry(&rmid_free_lru,
170 				 struct rmid_entry, list);
171 	list_del(&entry->list);
172 
173 	return entry->rmid;
174 }
175 
add_rmid_to_limbo(struct rmid_entry * entry)176 static void add_rmid_to_limbo(struct rmid_entry *entry)
177 {
178 	struct rdt_resource *r;
179 	struct rdt_domain *d;
180 	int cpu;
181 	u64 val;
182 
183 	r = &rdt_resources_all[RDT_RESOURCE_L3];
184 
185 	entry->busy = 0;
186 	cpu = get_cpu();
187 	list_for_each_entry(d, &r->domains, list) {
188 		if (cpumask_test_cpu(cpu, &d->cpu_mask)) {
189 			val = __rmid_read(entry->rmid, QOS_L3_OCCUP_EVENT_ID);
190 			if (val <= intel_cqm_threshold)
191 				continue;
192 		}
193 
194 		/*
195 		 * For the first limbo RMID in the domain,
196 		 * setup up the limbo worker.
197 		 */
198 		if (!has_busy_rmid(r, d))
199 			cqm_setup_limbo_handler(d, CQM_LIMBOCHECK_INTERVAL);
200 		set_bit(entry->rmid, d->rmid_busy_llc);
201 		entry->busy++;
202 	}
203 	put_cpu();
204 
205 	if (entry->busy)
206 		rmid_limbo_count++;
207 	else
208 		list_add_tail(&entry->list, &rmid_free_lru);
209 }
210 
free_rmid(u32 rmid)211 void free_rmid(u32 rmid)
212 {
213 	struct rmid_entry *entry;
214 
215 	if (!rmid)
216 		return;
217 
218 	lockdep_assert_held(&rdtgroup_mutex);
219 
220 	entry = __rmid_entry(rmid);
221 
222 	if (is_llc_occupancy_enabled())
223 		add_rmid_to_limbo(entry);
224 	else
225 		list_add_tail(&entry->list, &rmid_free_lru);
226 }
227 
mbm_overflow_count(u64 prev_msr,u64 cur_msr)228 static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr)
229 {
230 	u64 shift = 64 - MBM_CNTR_WIDTH, chunks;
231 
232 	chunks = (cur_msr << shift) - (prev_msr << shift);
233 	return chunks >>= shift;
234 }
235 
__mon_event_count(u32 rmid,struct rmid_read * rr)236 static int __mon_event_count(u32 rmid, struct rmid_read *rr)
237 {
238 	struct mbm_state *m;
239 	u64 chunks, tval;
240 
241 	tval = __rmid_read(rmid, rr->evtid);
242 	if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL)) {
243 		rr->val = tval;
244 		return -EINVAL;
245 	}
246 	switch (rr->evtid) {
247 	case QOS_L3_OCCUP_EVENT_ID:
248 		rr->val += tval;
249 		return 0;
250 	case QOS_L3_MBM_TOTAL_EVENT_ID:
251 		m = &rr->d->mbm_total[rmid];
252 		break;
253 	case QOS_L3_MBM_LOCAL_EVENT_ID:
254 		m = &rr->d->mbm_local[rmid];
255 		break;
256 	default:
257 		/*
258 		 * Code would never reach here because
259 		 * an invalid event id would fail the __rmid_read.
260 		 */
261 		return -EINVAL;
262 	}
263 
264 	if (rr->first) {
265 		memset(m, 0, sizeof(struct mbm_state));
266 		m->prev_bw_msr = m->prev_msr = tval;
267 		return 0;
268 	}
269 
270 	chunks = mbm_overflow_count(m->prev_msr, tval);
271 	m->chunks += chunks;
272 	m->prev_msr = tval;
273 
274 	rr->val += m->chunks;
275 	return 0;
276 }
277 
278 /*
279  * Supporting function to calculate the memory bandwidth
280  * and delta bandwidth in MBps.
281  */
mbm_bw_count(u32 rmid,struct rmid_read * rr)282 static void mbm_bw_count(u32 rmid, struct rmid_read *rr)
283 {
284 	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3];
285 	struct mbm_state *m = &rr->d->mbm_local[rmid];
286 	u64 tval, cur_bw, chunks;
287 
288 	tval = __rmid_read(rmid, rr->evtid);
289 	if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL))
290 		return;
291 
292 	chunks = mbm_overflow_count(m->prev_bw_msr, tval);
293 	m->chunks_bw += chunks;
294 	m->chunks = m->chunks_bw;
295 	cur_bw = (chunks * r->mon_scale) >> 20;
296 
297 	if (m->delta_comp)
298 		m->delta_bw = abs(cur_bw - m->prev_bw);
299 	m->delta_comp = false;
300 	m->prev_bw = cur_bw;
301 	m->prev_bw_msr = tval;
302 }
303 
304 /*
305  * This is called via IPI to read the CQM/MBM counters
306  * on a domain.
307  */
mon_event_count(void * info)308 void mon_event_count(void *info)
309 {
310 	struct rdtgroup *rdtgrp, *entry;
311 	struct rmid_read *rr = info;
312 	struct list_head *head;
313 
314 	rdtgrp = rr->rgrp;
315 
316 	if (__mon_event_count(rdtgrp->mon.rmid, rr))
317 		return;
318 
319 	/*
320 	 * For Ctrl groups read data from child monitor groups.
321 	 */
322 	head = &rdtgrp->mon.crdtgrp_list;
323 
324 	if (rdtgrp->type == RDTCTRL_GROUP) {
325 		list_for_each_entry(entry, head, mon.crdtgrp_list) {
326 			if (__mon_event_count(entry->mon.rmid, rr))
327 				return;
328 		}
329 	}
330 }
331 
332 /*
333  * Feedback loop for MBA software controller (mba_sc)
334  *
335  * mba_sc is a feedback loop where we periodically read MBM counters and
336  * adjust the bandwidth percentage values via the IA32_MBA_THRTL_MSRs so
337  * that:
338  *
339  *   current bandwdith(cur_bw) < user specified bandwidth(user_bw)
340  *
341  * This uses the MBM counters to measure the bandwidth and MBA throttle
342  * MSRs to control the bandwidth for a particular rdtgrp. It builds on the
343  * fact that resctrl rdtgroups have both monitoring and control.
344  *
345  * The frequency of the checks is 1s and we just tag along the MBM overflow
346  * timer. Having 1s interval makes the calculation of bandwidth simpler.
347  *
348  * Although MBA's goal is to restrict the bandwidth to a maximum, there may
349  * be a need to increase the bandwidth to avoid uncecessarily restricting
350  * the L2 <-> L3 traffic.
351  *
352  * Since MBA controls the L2 external bandwidth where as MBM measures the
353  * L3 external bandwidth the following sequence could lead to such a
354  * situation.
355  *
356  * Consider an rdtgroup which had high L3 <-> memory traffic in initial
357  * phases -> mba_sc kicks in and reduced bandwidth percentage values -> but
358  * after some time rdtgroup has mostly L2 <-> L3 traffic.
359  *
360  * In this case we may restrict the rdtgroup's L2 <-> L3 traffic as its
361  * throttle MSRs already have low percentage values.  To avoid
362  * unnecessarily restricting such rdtgroups, we also increase the bandwidth.
363  */
update_mba_bw(struct rdtgroup * rgrp,struct rdt_domain * dom_mbm)364 static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_domain *dom_mbm)
365 {
366 	u32 closid, rmid, cur_msr, cur_msr_val, new_msr_val;
367 	struct mbm_state *pmbm_data, *cmbm_data;
368 	u32 cur_bw, delta_bw, user_bw;
369 	struct rdt_resource *r_mba;
370 	struct rdt_domain *dom_mba;
371 	struct list_head *head;
372 	struct rdtgroup *entry;
373 
374 	r_mba = &rdt_resources_all[RDT_RESOURCE_MBA];
375 	closid = rgrp->closid;
376 	rmid = rgrp->mon.rmid;
377 	pmbm_data = &dom_mbm->mbm_local[rmid];
378 
379 	dom_mba = get_domain_from_cpu(smp_processor_id(), r_mba);
380 	if (!dom_mba) {
381 		pr_warn_once("Failure to get domain for MBA update\n");
382 		return;
383 	}
384 
385 	cur_bw = pmbm_data->prev_bw;
386 	user_bw = dom_mba->mbps_val[closid];
387 	delta_bw = pmbm_data->delta_bw;
388 	cur_msr_val = dom_mba->ctrl_val[closid];
389 
390 	/*
391 	 * For Ctrl groups read data from child monitor groups.
392 	 */
393 	head = &rgrp->mon.crdtgrp_list;
394 	list_for_each_entry(entry, head, mon.crdtgrp_list) {
395 		cmbm_data = &dom_mbm->mbm_local[entry->mon.rmid];
396 		cur_bw += cmbm_data->prev_bw;
397 		delta_bw += cmbm_data->delta_bw;
398 	}
399 
400 	/*
401 	 * Scale up/down the bandwidth linearly for the ctrl group.  The
402 	 * bandwidth step is the bandwidth granularity specified by the
403 	 * hardware.
404 	 *
405 	 * The delta_bw is used when increasing the bandwidth so that we
406 	 * dont alternately increase and decrease the control values
407 	 * continuously.
408 	 *
409 	 * For ex: consider cur_bw = 90MBps, user_bw = 100MBps and if
410 	 * bandwidth step is 20MBps(> user_bw - cur_bw), we would keep
411 	 * switching between 90 and 110 continuously if we only check
412 	 * cur_bw < user_bw.
413 	 */
414 	if (cur_msr_val > r_mba->membw.min_bw && user_bw < cur_bw) {
415 		new_msr_val = cur_msr_val - r_mba->membw.bw_gran;
416 	} else if (cur_msr_val < MAX_MBA_BW &&
417 		   (user_bw > (cur_bw + delta_bw))) {
418 		new_msr_val = cur_msr_val + r_mba->membw.bw_gran;
419 	} else {
420 		return;
421 	}
422 
423 	cur_msr = r_mba->msr_base + closid;
424 	wrmsrl(cur_msr, delay_bw_map(new_msr_val, r_mba));
425 	dom_mba->ctrl_val[closid] = new_msr_val;
426 
427 	/*
428 	 * Delta values are updated dynamically package wise for each
429 	 * rdtgrp everytime the throttle MSR changes value.
430 	 *
431 	 * This is because (1)the increase in bandwidth is not perfectly
432 	 * linear and only "approximately" linear even when the hardware
433 	 * says it is linear.(2)Also since MBA is a core specific
434 	 * mechanism, the delta values vary based on number of cores used
435 	 * by the rdtgrp.
436 	 */
437 	pmbm_data->delta_comp = true;
438 	list_for_each_entry(entry, head, mon.crdtgrp_list) {
439 		cmbm_data = &dom_mbm->mbm_local[entry->mon.rmid];
440 		cmbm_data->delta_comp = true;
441 	}
442 }
443 
mbm_update(struct rdt_domain * d,int rmid)444 static void mbm_update(struct rdt_domain *d, int rmid)
445 {
446 	struct rmid_read rr;
447 
448 	rr.first = false;
449 	rr.d = d;
450 
451 	/*
452 	 * This is protected from concurrent reads from user
453 	 * as both the user and we hold the global mutex.
454 	 */
455 	if (is_mbm_total_enabled()) {
456 		rr.evtid = QOS_L3_MBM_TOTAL_EVENT_ID;
457 		__mon_event_count(rmid, &rr);
458 	}
459 	if (is_mbm_local_enabled()) {
460 		rr.evtid = QOS_L3_MBM_LOCAL_EVENT_ID;
461 
462 		/*
463 		 * Call the MBA software controller only for the
464 		 * control groups and when user has enabled
465 		 * the software controller explicitly.
466 		 */
467 		if (!is_mba_sc(NULL))
468 			__mon_event_count(rmid, &rr);
469 		else
470 			mbm_bw_count(rmid, &rr);
471 	}
472 }
473 
474 /*
475  * Handler to scan the limbo list and move the RMIDs
476  * to free list whose occupancy < threshold_occupancy.
477  */
cqm_handle_limbo(struct work_struct * work)478 void cqm_handle_limbo(struct work_struct *work)
479 {
480 	unsigned long delay = msecs_to_jiffies(CQM_LIMBOCHECK_INTERVAL);
481 	int cpu = smp_processor_id();
482 	struct rdt_resource *r;
483 	struct rdt_domain *d;
484 
485 	mutex_lock(&rdtgroup_mutex);
486 
487 	r = &rdt_resources_all[RDT_RESOURCE_L3];
488 	d = get_domain_from_cpu(cpu, r);
489 
490 	if (!d) {
491 		pr_warn_once("Failure to get domain for limbo worker\n");
492 		goto out_unlock;
493 	}
494 
495 	__check_limbo(d, false);
496 
497 	if (has_busy_rmid(r, d))
498 		schedule_delayed_work_on(cpu, &d->cqm_limbo, delay);
499 
500 out_unlock:
501 	mutex_unlock(&rdtgroup_mutex);
502 }
503 
cqm_setup_limbo_handler(struct rdt_domain * dom,unsigned long delay_ms)504 void cqm_setup_limbo_handler(struct rdt_domain *dom, unsigned long delay_ms)
505 {
506 	unsigned long delay = msecs_to_jiffies(delay_ms);
507 	struct rdt_resource *r;
508 	int cpu;
509 
510 	r = &rdt_resources_all[RDT_RESOURCE_L3];
511 
512 	cpu = cpumask_any(&dom->cpu_mask);
513 	dom->cqm_work_cpu = cpu;
514 
515 	schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay);
516 }
517 
mbm_handle_overflow(struct work_struct * work)518 void mbm_handle_overflow(struct work_struct *work)
519 {
520 	unsigned long delay = msecs_to_jiffies(MBM_OVERFLOW_INTERVAL);
521 	struct rdtgroup *prgrp, *crgrp;
522 	int cpu = smp_processor_id();
523 	struct list_head *head;
524 	struct rdt_domain *d;
525 
526 	mutex_lock(&rdtgroup_mutex);
527 
528 	if (!static_branch_likely(&rdt_enable_key))
529 		goto out_unlock;
530 
531 	d = get_domain_from_cpu(cpu, &rdt_resources_all[RDT_RESOURCE_L3]);
532 	if (!d)
533 		goto out_unlock;
534 
535 	list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
536 		mbm_update(d, prgrp->mon.rmid);
537 
538 		head = &prgrp->mon.crdtgrp_list;
539 		list_for_each_entry(crgrp, head, mon.crdtgrp_list)
540 			mbm_update(d, crgrp->mon.rmid);
541 
542 		if (is_mba_sc(NULL))
543 			update_mba_bw(prgrp, d);
544 	}
545 
546 	schedule_delayed_work_on(cpu, &d->mbm_over, delay);
547 
548 out_unlock:
549 	mutex_unlock(&rdtgroup_mutex);
550 }
551 
mbm_setup_overflow_handler(struct rdt_domain * dom,unsigned long delay_ms)552 void mbm_setup_overflow_handler(struct rdt_domain *dom, unsigned long delay_ms)
553 {
554 	unsigned long delay = msecs_to_jiffies(delay_ms);
555 	int cpu;
556 
557 	if (!static_branch_likely(&rdt_enable_key))
558 		return;
559 	cpu = cpumask_any(&dom->cpu_mask);
560 	dom->mbm_work_cpu = cpu;
561 	schedule_delayed_work_on(cpu, &dom->mbm_over, delay);
562 }
563 
dom_data_init(struct rdt_resource * r)564 static int dom_data_init(struct rdt_resource *r)
565 {
566 	struct rmid_entry *entry = NULL;
567 	int i, nr_rmids;
568 
569 	nr_rmids = r->num_rmid;
570 	rmid_ptrs = kcalloc(nr_rmids, sizeof(struct rmid_entry), GFP_KERNEL);
571 	if (!rmid_ptrs)
572 		return -ENOMEM;
573 
574 	for (i = 0; i < nr_rmids; i++) {
575 		entry = &rmid_ptrs[i];
576 		INIT_LIST_HEAD(&entry->list);
577 
578 		entry->rmid = i;
579 		list_add_tail(&entry->list, &rmid_free_lru);
580 	}
581 
582 	/*
583 	 * RMID 0 is special and is always allocated. It's used for all
584 	 * tasks that are not monitored.
585 	 */
586 	entry = __rmid_entry(0);
587 	list_del(&entry->list);
588 
589 	return 0;
590 }
591 
592 static struct mon_evt llc_occupancy_event = {
593 	.name		= "llc_occupancy",
594 	.evtid		= QOS_L3_OCCUP_EVENT_ID,
595 };
596 
597 static struct mon_evt mbm_total_event = {
598 	.name		= "mbm_total_bytes",
599 	.evtid		= QOS_L3_MBM_TOTAL_EVENT_ID,
600 };
601 
602 static struct mon_evt mbm_local_event = {
603 	.name		= "mbm_local_bytes",
604 	.evtid		= QOS_L3_MBM_LOCAL_EVENT_ID,
605 };
606 
607 /*
608  * Initialize the event list for the resource.
609  *
610  * Note that MBM events are also part of RDT_RESOURCE_L3 resource
611  * because as per the SDM the total and local memory bandwidth
612  * are enumerated as part of L3 monitoring.
613  */
l3_mon_evt_init(struct rdt_resource * r)614 static void l3_mon_evt_init(struct rdt_resource *r)
615 {
616 	INIT_LIST_HEAD(&r->evt_list);
617 
618 	if (is_llc_occupancy_enabled())
619 		list_add_tail(&llc_occupancy_event.list, &r->evt_list);
620 	if (is_mbm_total_enabled())
621 		list_add_tail(&mbm_total_event.list, &r->evt_list);
622 	if (is_mbm_local_enabled())
623 		list_add_tail(&mbm_local_event.list, &r->evt_list);
624 }
625 
rdt_get_mon_l3_config(struct rdt_resource * r)626 int rdt_get_mon_l3_config(struct rdt_resource *r)
627 {
628 	int ret;
629 
630 	r->mon_scale = boot_cpu_data.x86_cache_occ_scale;
631 	r->num_rmid = boot_cpu_data.x86_cache_max_rmid + 1;
632 
633 	/*
634 	 * A reasonable upper limit on the max threshold is the number
635 	 * of lines tagged per RMID if all RMIDs have the same number of
636 	 * lines tagged in the LLC.
637 	 *
638 	 * For a 35MB LLC and 56 RMIDs, this is ~1.8% of the LLC.
639 	 */
640 	intel_cqm_threshold = boot_cpu_data.x86_cache_size * 1024 / r->num_rmid;
641 
642 	/* h/w works in units of "boot_cpu_data.x86_cache_occ_scale" */
643 	intel_cqm_threshold /= r->mon_scale;
644 
645 	ret = dom_data_init(r);
646 	if (ret)
647 		return ret;
648 
649 	l3_mon_evt_init(r);
650 
651 	r->mon_capable = true;
652 	r->mon_enabled = true;
653 
654 	return 0;
655 }
656