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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Resource Director Technology(RDT)
4 * - Monitoring code
5 *
6 * Copyright (C) 2017 Intel Corporation
7 *
8 * Author:
9 * Vikas Shivappa <vikas.shivappa@intel.com>
10 *
11 * This replaces the cqm.c based on perf but we reuse a lot of
12 * code and datastructures originally from Peter Zijlstra and Matt Fleming.
13 *
14 * More information about RDT be found in the Intel (R) x86 Architecture
15 * Software Developer Manual June 2016, volume 3, section 17.17.
16 */
17
18#include <linux/module.h>
19#include <linux/slab.h>
20#include <asm/cpu_device_id.h>
21#include "internal.h"
22
23struct rmid_entry {
24 u32 rmid;
25 int busy;
26 struct list_head list;
27};
28
29/**
30 * @rmid_free_lru A least recently used list of free RMIDs
31 * These RMIDs are guaranteed to have an occupancy less than the
32 * threshold occupancy
33 */
34static LIST_HEAD(rmid_free_lru);
35
36/**
37 * @rmid_limbo_count count of currently unused but (potentially)
38 * dirty RMIDs.
39 * This counts RMIDs that no one is currently using but that
40 * may have a occupancy value > intel_cqm_threshold. User can change
41 * the threshold occupancy value.
42 */
43static unsigned int rmid_limbo_count;
44
45/**
46 * @rmid_entry - The entry in the limbo and free lists.
47 */
48static struct rmid_entry *rmid_ptrs;
49
50/*
51 * Global boolean for rdt_monitor which is true if any
52 * resource monitoring is enabled.
53 */
54bool rdt_mon_capable;
55
56/*
57 * Global to indicate which monitoring events are enabled.
58 */
59unsigned int rdt_mon_features;
60
61/*
62 * This is the threshold cache occupancy at which we will consider an
63 * RMID available for re-allocation.
64 */
65unsigned int resctrl_cqm_threshold;
66
67static inline struct rmid_entry *__rmid_entry(u32 rmid)
68{
69 struct rmid_entry *entry;
70
71 entry = &rmid_ptrs[rmid];
72 WARN_ON(entry->rmid != rmid);
73
74 return entry;
75}
76
77static u64 __rmid_read(u32 rmid, u32 eventid)
78{
79 u64 val;
80
81 /*
82 * As per the SDM, when IA32_QM_EVTSEL.EvtID (bits 7:0) is configured
83 * with a valid event code for supported resource type and the bits
84 * IA32_QM_EVTSEL.RMID (bits 41:32) are configured with valid RMID,
85 * IA32_QM_CTR.data (bits 61:0) reports the monitored data.
86 * IA32_QM_CTR.Error (bit 63) and IA32_QM_CTR.Unavailable (bit 62)
87 * are error bits.
88 */
89 wrmsr(MSR_IA32_QM_EVTSEL, eventid, rmid);
90 rdmsrl(MSR_IA32_QM_CTR, val);
91
92 return val;
93}
94
95static bool rmid_dirty(struct rmid_entry *entry)
96{
97 u64 val = __rmid_read(entry->rmid, QOS_L3_OCCUP_EVENT_ID);
98
99 return val >= resctrl_cqm_threshold;
100}
101
102/*
103 * Check the RMIDs that are marked as busy for this domain. If the
104 * reported LLC occupancy is below the threshold clear the busy bit and
105 * decrement the count. If the busy count gets to zero on an RMID, we
106 * free the RMID
107 */
108void __check_limbo(struct rdt_domain *d, bool force_free)
109{
110 struct rmid_entry *entry;
111 struct rdt_resource *r;
112 u32 crmid = 1, nrmid;
113
114 r = &rdt_resources_all[RDT_RESOURCE_L3];
115
116 /*
117 * Skip RMID 0 and start from RMID 1 and check all the RMIDs that
118 * are marked as busy for occupancy < threshold. If the occupancy
119 * is less than the threshold decrement the busy counter of the
120 * RMID and move it to the free list when the counter reaches 0.
121 */
122 for (;;) {
123 nrmid = find_next_bit(d->rmid_busy_llc, r->num_rmid, crmid);
124 if (nrmid >= r->num_rmid)
125 break;
126
127 entry = __rmid_entry(nrmid);
128 if (force_free || !rmid_dirty(entry)) {
129 clear_bit(entry->rmid, d->rmid_busy_llc);
130 if (!--entry->busy) {
131 rmid_limbo_count--;
132 list_add_tail(&entry->list, &rmid_free_lru);
133 }
134 }
135 crmid = nrmid + 1;
136 }
137}
138
139bool has_busy_rmid(struct rdt_resource *r, struct rdt_domain *d)
140{
141 return find_first_bit(d->rmid_busy_llc, r->num_rmid) != r->num_rmid;
142}
143
144/*
145 * As of now the RMIDs allocation is global.
146 * However we keep track of which packages the RMIDs
147 * are used to optimize the limbo list management.
148 */
149int alloc_rmid(void)
150{
151 struct rmid_entry *entry;
152
153 lockdep_assert_held(&rdtgroup_mutex);
154
155 if (list_empty(&rmid_free_lru))
156 return rmid_limbo_count ? -EBUSY : -ENOSPC;
157
158 entry = list_first_entry(&rmid_free_lru,
159 struct rmid_entry, list);
160 list_del(&entry->list);
161
162 return entry->rmid;
163}
164
165static void add_rmid_to_limbo(struct rmid_entry *entry)
166{
167 struct rdt_resource *r;
168 struct rdt_domain *d;
169 int cpu;
170 u64 val;
171
172 r = &rdt_resources_all[RDT_RESOURCE_L3];
173
174 entry->busy = 0;
175 cpu = get_cpu();
176 list_for_each_entry(d, &r->domains, list) {
177 if (cpumask_test_cpu(cpu, &d->cpu_mask)) {
178 val = __rmid_read(entry->rmid, QOS_L3_OCCUP_EVENT_ID);
179 if (val <= resctrl_cqm_threshold)
180 continue;
181 }
182
183 /*
184 * For the first limbo RMID in the domain,
185 * setup up the limbo worker.
186 */
187 if (!has_busy_rmid(r, d))
188 cqm_setup_limbo_handler(d, CQM_LIMBOCHECK_INTERVAL);
189 set_bit(entry->rmid, d->rmid_busy_llc);
190 entry->busy++;
191 }
192 put_cpu();
193
194 if (entry->busy)
195 rmid_limbo_count++;
196 else
197 list_add_tail(&entry->list, &rmid_free_lru);
198}
199
200void free_rmid(u32 rmid)
201{
202 struct rmid_entry *entry;
203
204 if (!rmid)
205 return;
206
207 lockdep_assert_held(&rdtgroup_mutex);
208
209 entry = __rmid_entry(rmid);
210
211 if (is_llc_occupancy_enabled())
212 add_rmid_to_limbo(entry);
213 else
214 list_add_tail(&entry->list, &rmid_free_lru);
215}
216
217static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr)
218{
219 u64 shift = 64 - MBM_CNTR_WIDTH, chunks;
220
221 chunks = (cur_msr << shift) - (prev_msr << shift);
222 return chunks >>= shift;
223}
224
225static int __mon_event_count(u32 rmid, struct rmid_read *rr)
226{
227 struct mbm_state *m;
228 u64 chunks, tval;
229
230 tval = __rmid_read(rmid, rr->evtid);
231 if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL)) {
232 rr->val = tval;
233 return -EINVAL;
234 }
235 switch (rr->evtid) {
236 case QOS_L3_OCCUP_EVENT_ID:
237 rr->val += tval;
238 return 0;
239 case QOS_L3_MBM_TOTAL_EVENT_ID:
240 m = &rr->d->mbm_total[rmid];
241 break;
242 case QOS_L3_MBM_LOCAL_EVENT_ID:
243 m = &rr->d->mbm_local[rmid];
244 break;
245 default:
246 /*
247 * Code would never reach here because
248 * an invalid event id would fail the __rmid_read.
249 */
250 return -EINVAL;
251 }
252
253 if (rr->first) {
254 memset(m, 0, sizeof(struct mbm_state));
255 m->prev_bw_msr = m->prev_msr = tval;
256 return 0;
257 }
258
259 chunks = mbm_overflow_count(m->prev_msr, tval);
260 m->chunks += chunks;
261 m->prev_msr = tval;
262
263 rr->val += m->chunks;
264 return 0;
265}
266
267/*
268 * Supporting function to calculate the memory bandwidth
269 * and delta bandwidth in MBps.
270 */
271static void mbm_bw_count(u32 rmid, struct rmid_read *rr)
272{
273 struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3];
274 struct mbm_state *m = &rr->d->mbm_local[rmid];
275 u64 tval, cur_bw, chunks;
276
277 tval = __rmid_read(rmid, rr->evtid);
278 if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL))
279 return;
280
281 chunks = mbm_overflow_count(m->prev_bw_msr, tval);
282 m->chunks_bw += chunks;
283 m->chunks = m->chunks_bw;
284 cur_bw = (chunks * r->mon_scale) >> 20;
285
286 if (m->delta_comp)
287 m->delta_bw = abs(cur_bw - m->prev_bw);
288 m->delta_comp = false;
289 m->prev_bw = cur_bw;
290 m->prev_bw_msr = tval;
291}
292
293/*
294 * This is called via IPI to read the CQM/MBM counters
295 * on a domain.
296 */
297void mon_event_count(void *info)
298{
299 struct rdtgroup *rdtgrp, *entry;
300 struct rmid_read *rr = info;
301 struct list_head *head;
302
303 rdtgrp = rr->rgrp;
304
305 if (__mon_event_count(rdtgrp->mon.rmid, rr))
306 return;
307
308 /*
309 * For Ctrl groups read data from child monitor groups.
310 */
311 head = &rdtgrp->mon.crdtgrp_list;
312
313 if (rdtgrp->type == RDTCTRL_GROUP) {
314 list_for_each_entry(entry, head, mon.crdtgrp_list) {
315 if (__mon_event_count(entry->mon.rmid, rr))
316 return;
317 }
318 }
319}
320
321/*
322 * Feedback loop for MBA software controller (mba_sc)
323 *
324 * mba_sc is a feedback loop where we periodically read MBM counters and
325 * adjust the bandwidth percentage values via the IA32_MBA_THRTL_MSRs so
326 * that:
327 *
328 * current bandwdith(cur_bw) < user specified bandwidth(user_bw)
329 *
330 * This uses the MBM counters to measure the bandwidth and MBA throttle
331 * MSRs to control the bandwidth for a particular rdtgrp. It builds on the
332 * fact that resctrl rdtgroups have both monitoring and control.
333 *
334 * The frequency of the checks is 1s and we just tag along the MBM overflow
335 * timer. Having 1s interval makes the calculation of bandwidth simpler.
336 *
337 * Although MBA's goal is to restrict the bandwidth to a maximum, there may
338 * be a need to increase the bandwidth to avoid uncecessarily restricting
339 * the L2 <-> L3 traffic.
340 *
341 * Since MBA controls the L2 external bandwidth where as MBM measures the
342 * L3 external bandwidth the following sequence could lead to such a
343 * situation.
344 *
345 * Consider an rdtgroup which had high L3 <-> memory traffic in initial
346 * phases -> mba_sc kicks in and reduced bandwidth percentage values -> but
347 * after some time rdtgroup has mostly L2 <-> L3 traffic.
348 *
349 * In this case we may restrict the rdtgroup's L2 <-> L3 traffic as its
350 * throttle MSRs already have low percentage values. To avoid
351 * unnecessarily restricting such rdtgroups, we also increase the bandwidth.
352 */
353static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_domain *dom_mbm)
354{
355 u32 closid, rmid, cur_msr, cur_msr_val, new_msr_val;
356 struct mbm_state *pmbm_data, *cmbm_data;
357 u32 cur_bw, delta_bw, user_bw;
358 struct rdt_resource *r_mba;
359 struct rdt_domain *dom_mba;
360 struct list_head *head;
361 struct rdtgroup *entry;
362
363 if (!is_mbm_local_enabled())
364 return;
365
366 r_mba = &rdt_resources_all[RDT_RESOURCE_MBA];
367 closid = rgrp->closid;
368 rmid = rgrp->mon.rmid;
369 pmbm_data = &dom_mbm->mbm_local[rmid];
370
371 dom_mba = get_domain_from_cpu(smp_processor_id(), r_mba);
372 if (!dom_mba) {
373 pr_warn_once("Failure to get domain for MBA update\n");
374 return;
375 }
376
377 cur_bw = pmbm_data->prev_bw;
378 user_bw = dom_mba->mbps_val[closid];
379 delta_bw = pmbm_data->delta_bw;
380 cur_msr_val = dom_mba->ctrl_val[closid];
381
382 /*
383 * For Ctrl groups read data from child monitor groups.
384 */
385 head = &rgrp->mon.crdtgrp_list;
386 list_for_each_entry(entry, head, mon.crdtgrp_list) {
387 cmbm_data = &dom_mbm->mbm_local[entry->mon.rmid];
388 cur_bw += cmbm_data->prev_bw;
389 delta_bw += cmbm_data->delta_bw;
390 }
391
392 /*
393 * Scale up/down the bandwidth linearly for the ctrl group. The
394 * bandwidth step is the bandwidth granularity specified by the
395 * hardware.
396 *
397 * The delta_bw is used when increasing the bandwidth so that we
398 * dont alternately increase and decrease the control values
399 * continuously.
400 *
401 * For ex: consider cur_bw = 90MBps, user_bw = 100MBps and if
402 * bandwidth step is 20MBps(> user_bw - cur_bw), we would keep
403 * switching between 90 and 110 continuously if we only check
404 * cur_bw < user_bw.
405 */
406 if (cur_msr_val > r_mba->membw.min_bw && user_bw < cur_bw) {
407 new_msr_val = cur_msr_val - r_mba->membw.bw_gran;
408 } else if (cur_msr_val < MAX_MBA_BW &&
409 (user_bw > (cur_bw + delta_bw))) {
410 new_msr_val = cur_msr_val + r_mba->membw.bw_gran;
411 } else {
412 return;
413 }
414
415 cur_msr = r_mba->msr_base + closid;
416 wrmsrl(cur_msr, delay_bw_map(new_msr_val, r_mba));
417 dom_mba->ctrl_val[closid] = new_msr_val;
418
419 /*
420 * Delta values are updated dynamically package wise for each
421 * rdtgrp everytime the throttle MSR changes value.
422 *
423 * This is because (1)the increase in bandwidth is not perfectly
424 * linear and only "approximately" linear even when the hardware
425 * says it is linear.(2)Also since MBA is a core specific
426 * mechanism, the delta values vary based on number of cores used
427 * by the rdtgrp.
428 */
429 pmbm_data->delta_comp = true;
430 list_for_each_entry(entry, head, mon.crdtgrp_list) {
431 cmbm_data = &dom_mbm->mbm_local[entry->mon.rmid];
432 cmbm_data->delta_comp = true;
433 }
434}
435
436static void mbm_update(struct rdt_domain *d, int rmid)
437{
438 struct rmid_read rr;
439
440 rr.first = false;
441 rr.d = d;
442
443 /*
444 * This is protected from concurrent reads from user
445 * as both the user and we hold the global mutex.
446 */
447 if (is_mbm_total_enabled()) {
448 rr.evtid = QOS_L3_MBM_TOTAL_EVENT_ID;
449 __mon_event_count(rmid, &rr);
450 }
451 if (is_mbm_local_enabled()) {
452 rr.evtid = QOS_L3_MBM_LOCAL_EVENT_ID;
453
454 /*
455 * Call the MBA software controller only for the
456 * control groups and when user has enabled
457 * the software controller explicitly.
458 */
459 if (!is_mba_sc(NULL))
460 __mon_event_count(rmid, &rr);
461 else
462 mbm_bw_count(rmid, &rr);
463 }
464}
465
466/*
467 * Handler to scan the limbo list and move the RMIDs
468 * to free list whose occupancy < threshold_occupancy.
469 */
470void cqm_handle_limbo(struct work_struct *work)
471{
472 unsigned long delay = msecs_to_jiffies(CQM_LIMBOCHECK_INTERVAL);
473 int cpu = smp_processor_id();
474 struct rdt_resource *r;
475 struct rdt_domain *d;
476
477 mutex_lock(&rdtgroup_mutex);
478
479 r = &rdt_resources_all[RDT_RESOURCE_L3];
480 d = get_domain_from_cpu(cpu, r);
481
482 if (!d) {
483 pr_warn_once("Failure to get domain for limbo worker\n");
484 goto out_unlock;
485 }
486
487 __check_limbo(d, false);
488
489 if (has_busy_rmid(r, d))
490 schedule_delayed_work_on(cpu, &d->cqm_limbo, delay);
491
492out_unlock:
493 mutex_unlock(&rdtgroup_mutex);
494}
495
496void cqm_setup_limbo_handler(struct rdt_domain *dom, unsigned long delay_ms)
497{
498 unsigned long delay = msecs_to_jiffies(delay_ms);
499 int cpu;
500
501 cpu = cpumask_any(&dom->cpu_mask);
502 dom->cqm_work_cpu = cpu;
503
504 schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay);
505}
506
507void mbm_handle_overflow(struct work_struct *work)
508{
509 unsigned long delay = msecs_to_jiffies(MBM_OVERFLOW_INTERVAL);
510 struct rdtgroup *prgrp, *crgrp;
511 int cpu = smp_processor_id();
512 struct list_head *head;
513 struct rdt_domain *d;
514
515 mutex_lock(&rdtgroup_mutex);
516
517 if (!static_branch_likely(&rdt_enable_key))
518 goto out_unlock;
519
520 d = get_domain_from_cpu(cpu, &rdt_resources_all[RDT_RESOURCE_L3]);
521 if (!d)
522 goto out_unlock;
523
524 list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
525 mbm_update(d, prgrp->mon.rmid);
526
527 head = &prgrp->mon.crdtgrp_list;
528 list_for_each_entry(crgrp, head, mon.crdtgrp_list)
529 mbm_update(d, crgrp->mon.rmid);
530
531 if (is_mba_sc(NULL))
532 update_mba_bw(prgrp, d);
533 }
534
535 schedule_delayed_work_on(cpu, &d->mbm_over, delay);
536
537out_unlock:
538 mutex_unlock(&rdtgroup_mutex);
539}
540
541void mbm_setup_overflow_handler(struct rdt_domain *dom, unsigned long delay_ms)
542{
543 unsigned long delay = msecs_to_jiffies(delay_ms);
544 int cpu;
545
546 if (!static_branch_likely(&rdt_enable_key))
547 return;
548 cpu = cpumask_any(&dom->cpu_mask);
549 dom->mbm_work_cpu = cpu;
550 schedule_delayed_work_on(cpu, &dom->mbm_over, delay);
551}
552
553static int dom_data_init(struct rdt_resource *r)
554{
555 struct rmid_entry *entry = NULL;
556 int i, nr_rmids;
557
558 nr_rmids = r->num_rmid;
559 rmid_ptrs = kcalloc(nr_rmids, sizeof(struct rmid_entry), GFP_KERNEL);
560 if (!rmid_ptrs)
561 return -ENOMEM;
562
563 for (i = 0; i < nr_rmids; i++) {
564 entry = &rmid_ptrs[i];
565 INIT_LIST_HEAD(&entry->list);
566
567 entry->rmid = i;
568 list_add_tail(&entry->list, &rmid_free_lru);
569 }
570
571 /*
572 * RMID 0 is special and is always allocated. It's used for all
573 * tasks that are not monitored.
574 */
575 entry = __rmid_entry(0);
576 list_del(&entry->list);
577
578 return 0;
579}
580
581static struct mon_evt llc_occupancy_event = {
582 .name = "llc_occupancy",
583 .evtid = QOS_L3_OCCUP_EVENT_ID,
584};
585
586static struct mon_evt mbm_total_event = {
587 .name = "mbm_total_bytes",
588 .evtid = QOS_L3_MBM_TOTAL_EVENT_ID,
589};
590
591static struct mon_evt mbm_local_event = {
592 .name = "mbm_local_bytes",
593 .evtid = QOS_L3_MBM_LOCAL_EVENT_ID,
594};
595
596/*
597 * Initialize the event list for the resource.
598 *
599 * Note that MBM events are also part of RDT_RESOURCE_L3 resource
600 * because as per the SDM the total and local memory bandwidth
601 * are enumerated as part of L3 monitoring.
602 */
603static void l3_mon_evt_init(struct rdt_resource *r)
604{
605 INIT_LIST_HEAD(&r->evt_list);
606
607 if (is_llc_occupancy_enabled())
608 list_add_tail(&llc_occupancy_event.list, &r->evt_list);
609 if (is_mbm_total_enabled())
610 list_add_tail(&mbm_total_event.list, &r->evt_list);
611 if (is_mbm_local_enabled())
612 list_add_tail(&mbm_local_event.list, &r->evt_list);
613}
614
615int rdt_get_mon_l3_config(struct rdt_resource *r)
616{
617 unsigned int cl_size = boot_cpu_data.x86_cache_size;
618 int ret;
619
620 r->mon_scale = boot_cpu_data.x86_cache_occ_scale;
621 r->num_rmid = boot_cpu_data.x86_cache_max_rmid + 1;
622
623 /*
624 * A reasonable upper limit on the max threshold is the number
625 * of lines tagged per RMID if all RMIDs have the same number of
626 * lines tagged in the LLC.
627 *
628 * For a 35MB LLC and 56 RMIDs, this is ~1.8% of the LLC.
629 */
630 resctrl_cqm_threshold = cl_size * 1024 / r->num_rmid;
631
632 /* h/w works in units of "boot_cpu_data.x86_cache_occ_scale" */
633 resctrl_cqm_threshold /= r->mon_scale;
634
635 ret = dom_data_init(r);
636 if (ret)
637 return ret;
638
639 l3_mon_evt_init(r);
640
641 r->mon_capable = true;
642 r->mon_enabled = true;
643
644 return 0;
645}