// SPDX-License-Identifier: GPL-2.0-only /* * Resource Director Technology(RDT) * - Monitoring code * * Copyright (C) 2017 Intel Corporation * * Author: * Vikas Shivappa * * This replaces the cqm.c based on perf but we reuse a lot of * code and datastructures originally from Peter Zijlstra and Matt Fleming. * * More information about RDT be found in the Intel (R) x86 Architecture * Software Developer Manual June 2016, volume 3, section 17.17. */ #include #include #include #include "internal.h" struct rmid_entry { u32 rmid; int busy; struct list_head list; }; /** * @rmid_free_lru A least recently used list of free RMIDs * These RMIDs are guaranteed to have an occupancy less than the * threshold occupancy */ static LIST_HEAD(rmid_free_lru); /** * @rmid_limbo_count count of currently unused but (potentially) * dirty RMIDs. * This counts RMIDs that no one is currently using but that * may have a occupancy value > intel_cqm_threshold. User can change * the threshold occupancy value. */ static unsigned int rmid_limbo_count; /** * @rmid_entry - The entry in the limbo and free lists. */ static struct rmid_entry *rmid_ptrs; /* * Global boolean for rdt_monitor which is true if any * resource monitoring is enabled. */ bool rdt_mon_capable; /* * Global to indicate which monitoring events are enabled. */ unsigned int rdt_mon_features; /* * This is the threshold cache occupancy at which we will consider an * RMID available for re-allocation. */ unsigned int resctrl_cqm_threshold; #define CF(cf) ((unsigned long)(1048576 * (cf) + 0.5)) /* * The correction factor table is documented in Documentation/x86/resctrl.rst. * If rmid > rmid threshold, MBM total and local values should be multiplied * by the correction factor. * * The original table is modified for better code: * * 1. The threshold 0 is changed to rmid count - 1 so don't do correction * for the case. * 2. MBM total and local correction table indexed by core counter which is * equal to (x86_cache_max_rmid + 1) / 8 - 1 and is from 0 up to 27. * 3. The correction factor is normalized to 2^20 (1048576) so it's faster * to calculate corrected value by shifting: * corrected_value = (original_value * correction_factor) >> 20 */ static const struct mbm_correction_factor_table { u32 rmidthreshold; u64 cf; } mbm_cf_table[] __initconst = { {7, CF(1.000000)}, {15, CF(1.000000)}, {15, CF(0.969650)}, {31, CF(1.000000)}, {31, CF(1.066667)}, {31, CF(0.969650)}, {47, CF(1.142857)}, {63, CF(1.000000)}, {63, CF(1.185115)}, {63, CF(1.066553)}, {79, CF(1.454545)}, {95, CF(1.000000)}, {95, CF(1.230769)}, {95, CF(1.142857)}, {95, CF(1.066667)}, {127, CF(1.000000)}, {127, CF(1.254863)}, {127, CF(1.185255)}, {151, CF(1.000000)}, {127, CF(1.066667)}, {167, CF(1.000000)}, {159, CF(1.454334)}, {183, CF(1.000000)}, {127, CF(0.969744)}, {191, CF(1.280246)}, {191, CF(1.230921)}, {215, CF(1.000000)}, {191, CF(1.143118)}, }; static u32 mbm_cf_rmidthreshold __read_mostly = UINT_MAX; static u64 mbm_cf __read_mostly; static inline u64 get_corrected_mbm_count(u32 rmid, unsigned long val) { /* Correct MBM value. */ if (rmid > mbm_cf_rmidthreshold) val = (val * mbm_cf) >> 20; return val; } static inline struct rmid_entry *__rmid_entry(u32 rmid) { struct rmid_entry *entry; entry = &rmid_ptrs[rmid]; WARN_ON(entry->rmid != rmid); return entry; } static u64 __rmid_read(u32 rmid, u32 eventid) { u64 val; /* * As per the SDM, when IA32_QM_EVTSEL.EvtID (bits 7:0) is configured * with a valid event code for supported resource type and the bits * IA32_QM_EVTSEL.RMID (bits 41:32) are configured with valid RMID, * IA32_QM_CTR.data (bits 61:0) reports the monitored data. * IA32_QM_CTR.Error (bit 63) and IA32_QM_CTR.Unavailable (bit 62) * are error bits. */ wrmsr(MSR_IA32_QM_EVTSEL, eventid, rmid); rdmsrl(MSR_IA32_QM_CTR, val); return val; } static bool rmid_dirty(struct rmid_entry *entry) { u64 val = __rmid_read(entry->rmid, QOS_L3_OCCUP_EVENT_ID); return val >= resctrl_cqm_threshold; } /* * Check the RMIDs that are marked as busy for this domain. If the * reported LLC occupancy is below the threshold clear the busy bit and * decrement the count. If the busy count gets to zero on an RMID, we * free the RMID */ void __check_limbo(struct rdt_domain *d, bool force_free) { struct rmid_entry *entry; struct rdt_resource *r; u32 crmid = 1, nrmid; r = &rdt_resources_all[RDT_RESOURCE_L3]; /* * Skip RMID 0 and start from RMID 1 and check all the RMIDs that * are marked as busy for occupancy < threshold. If the occupancy * is less than the threshold decrement the busy counter of the * RMID and move it to the free list when the counter reaches 0. */ for (;;) { nrmid = find_next_bit(d->rmid_busy_llc, r->num_rmid, crmid); if (nrmid >= r->num_rmid) break; entry = __rmid_entry(nrmid); if (force_free || !rmid_dirty(entry)) { clear_bit(entry->rmid, d->rmid_busy_llc); if (!--entry->busy) { rmid_limbo_count--; list_add_tail(&entry->list, &rmid_free_lru); } } crmid = nrmid + 1; } } bool has_busy_rmid(struct rdt_resource *r, struct rdt_domain *d) { return find_first_bit(d->rmid_busy_llc, r->num_rmid) != r->num_rmid; } /* * As of now the RMIDs allocation is global. * However we keep track of which packages the RMIDs * are used to optimize the limbo list management. */ int alloc_rmid(void) { struct rmid_entry *entry; lockdep_assert_held(&rdtgroup_mutex); if (list_empty(&rmid_free_lru)) return rmid_limbo_count ? -EBUSY : -ENOSPC; entry = list_first_entry(&rmid_free_lru, struct rmid_entry, list); list_del(&entry->list); return entry->rmid; } static void add_rmid_to_limbo(struct rmid_entry *entry) { struct rdt_resource *r; struct rdt_domain *d; int cpu; u64 val; r = &rdt_resources_all[RDT_RESOURCE_L3]; entry->busy = 0; cpu = get_cpu(); list_for_each_entry(d, &r->domains, list) { if (cpumask_test_cpu(cpu, &d->cpu_mask)) { val = __rmid_read(entry->rmid, QOS_L3_OCCUP_EVENT_ID); if (val <= resctrl_cqm_threshold) continue; } /* * For the first limbo RMID in the domain, * setup up the limbo worker. */ if (!has_busy_rmid(r, d)) cqm_setup_limbo_handler(d, CQM_LIMBOCHECK_INTERVAL); set_bit(entry->rmid, d->rmid_busy_llc); entry->busy++; } put_cpu(); if (entry->busy) rmid_limbo_count++; else list_add_tail(&entry->list, &rmid_free_lru); } void free_rmid(u32 rmid) { struct rmid_entry *entry; if (!rmid) return; lockdep_assert_held(&rdtgroup_mutex); entry = __rmid_entry(rmid); if (is_llc_occupancy_enabled()) add_rmid_to_limbo(entry); else list_add_tail(&entry->list, &rmid_free_lru); } static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width) { u64 shift = 64 - width, chunks; chunks = (cur_msr << shift) - (prev_msr << shift); return chunks >>= shift; } static u64 __mon_event_count(u32 rmid, struct rmid_read *rr) { struct mbm_state *m; u64 chunks, tval; tval = __rmid_read(rmid, rr->evtid); if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL)) { return tval; } switch (rr->evtid) { case QOS_L3_OCCUP_EVENT_ID: rr->val += tval; return 0; case QOS_L3_MBM_TOTAL_EVENT_ID: m = &rr->d->mbm_total[rmid]; break; case QOS_L3_MBM_LOCAL_EVENT_ID: m = &rr->d->mbm_local[rmid]; break; } if (rr->first) { memset(m, 0, sizeof(struct mbm_state)); m->prev_bw_msr = m->prev_msr = tval; return 0; } chunks = mbm_overflow_count(m->prev_msr, tval, rr->r->mbm_width); m->chunks += chunks; m->prev_msr = tval; rr->val += get_corrected_mbm_count(rmid, m->chunks); return 0; } /* * Supporting function to calculate the memory bandwidth * and delta bandwidth in MBps. */ static void mbm_bw_count(u32 rmid, struct rmid_read *rr) { struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3]; struct mbm_state *m = &rr->d->mbm_local[rmid]; u64 tval, cur_bw, chunks; tval = __rmid_read(rmid, rr->evtid); if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL)) return; chunks = mbm_overflow_count(m->prev_bw_msr, tval, rr->r->mbm_width); cur_bw = (get_corrected_mbm_count(rmid, chunks) * r->mon_scale) >> 20; if (m->delta_comp) m->delta_bw = abs(cur_bw - m->prev_bw); m->delta_comp = false; m->prev_bw = cur_bw; m->prev_bw_msr = tval; } /* * This is called via IPI to read the CQM/MBM counters * on a domain. */ void mon_event_count(void *info) { struct rdtgroup *rdtgrp, *entry; struct rmid_read *rr = info; struct list_head *head; u64 ret_val; rdtgrp = rr->rgrp; ret_val = __mon_event_count(rdtgrp->mon.rmid, rr); /* * For Ctrl groups read data from child monitor groups and * add them together. Count events which are read successfully. * Discard the rmid_read's reporting errors. */ head = &rdtgrp->mon.crdtgrp_list; if (rdtgrp->type == RDTCTRL_GROUP) { list_for_each_entry(entry, head, mon.crdtgrp_list) { if (__mon_event_count(entry->mon.rmid, rr) == 0) ret_val = 0; } } /* Report error if none of rmid_reads are successful */ if (ret_val) rr->val = ret_val; } /* * Feedback loop for MBA software controller (mba_sc) * * mba_sc is a feedback loop where we periodically read MBM counters and * adjust the bandwidth percentage values via the IA32_MBA_THRTL_MSRs so * that: * * current bandwidth(cur_bw) < user specified bandwidth(user_bw) * * This uses the MBM counters to measure the bandwidth and MBA throttle * MSRs to control the bandwidth for a particular rdtgrp. It builds on the * fact that resctrl rdtgroups have both monitoring and control. * * The frequency of the checks is 1s and we just tag along the MBM overflow * timer. Having 1s interval makes the calculation of bandwidth simpler. * * Although MBA's goal is to restrict the bandwidth to a maximum, there may * be a need to increase the bandwidth to avoid unnecessarily restricting * the L2 <-> L3 traffic. * * Since MBA controls the L2 external bandwidth where as MBM measures the * L3 external bandwidth the following sequence could lead to such a * situation. * * Consider an rdtgroup which had high L3 <-> memory traffic in initial * phases -> mba_sc kicks in and reduced bandwidth percentage values -> but * after some time rdtgroup has mostly L2 <-> L3 traffic. * * In this case we may restrict the rdtgroup's L2 <-> L3 traffic as its * throttle MSRs already have low percentage values. To avoid * unnecessarily restricting such rdtgroups, we also increase the bandwidth. */ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_domain *dom_mbm) { u32 closid, rmid, cur_msr, cur_msr_val, new_msr_val; struct mbm_state *pmbm_data, *cmbm_data; u32 cur_bw, delta_bw, user_bw; struct rdt_resource *r_mba; struct rdt_domain *dom_mba; struct list_head *head; struct rdtgroup *entry; if (!is_mbm_local_enabled()) return; r_mba = &rdt_resources_all[RDT_RESOURCE_MBA]; closid = rgrp->closid; rmid = rgrp->mon.rmid; pmbm_data = &dom_mbm->mbm_local[rmid]; dom_mba = get_domain_from_cpu(smp_processor_id(), r_mba); if (!dom_mba) { pr_warn_once("Failure to get domain for MBA update\n"); return; } cur_bw = pmbm_data->prev_bw; user_bw = dom_mba->mbps_val[closid]; delta_bw = pmbm_data->delta_bw; cur_msr_val = dom_mba->ctrl_val[closid]; /* * For Ctrl groups read data from child monitor groups. */ head = &rgrp->mon.crdtgrp_list; list_for_each_entry(entry, head, mon.crdtgrp_list) { cmbm_data = &dom_mbm->mbm_local[entry->mon.rmid]; cur_bw += cmbm_data->prev_bw; delta_bw += cmbm_data->delta_bw; } /* * Scale up/down the bandwidth linearly for the ctrl group. The * bandwidth step is the bandwidth granularity specified by the * hardware. * * The delta_bw is used when increasing the bandwidth so that we * dont alternately increase and decrease the control values * continuously. * * For ex: consider cur_bw = 90MBps, user_bw = 100MBps and if * bandwidth step is 20MBps(> user_bw - cur_bw), we would keep * switching between 90 and 110 continuously if we only check * cur_bw < user_bw. */ if (cur_msr_val > r_mba->membw.min_bw && user_bw < cur_bw) { new_msr_val = cur_msr_val - r_mba->membw.bw_gran; } else if (cur_msr_val < MAX_MBA_BW && (user_bw > (cur_bw + delta_bw))) { new_msr_val = cur_msr_val + r_mba->membw.bw_gran; } else { return; } cur_msr = r_mba->msr_base + closid; wrmsrl(cur_msr, delay_bw_map(new_msr_val, r_mba)); dom_mba->ctrl_val[closid] = new_msr_val; /* * Delta values are updated dynamically package wise for each * rdtgrp every time the throttle MSR changes value. * * This is because (1)the increase in bandwidth is not perfectly * linear and only "approximately" linear even when the hardware * says it is linear.(2)Also since MBA is a core specific * mechanism, the delta values vary based on number of cores used * by the rdtgrp. */ pmbm_data->delta_comp = true; list_for_each_entry(entry, head, mon.crdtgrp_list) { cmbm_data = &dom_mbm->mbm_local[entry->mon.rmid]; cmbm_data->delta_comp = true; } } static void mbm_update(struct rdt_resource *r, struct rdt_domain *d, int rmid) { struct rmid_read rr; rr.first = false; rr.r = r; rr.d = d; /* * This is protected from concurrent reads from user * as both the user and we hold the global mutex. */ if (is_mbm_total_enabled()) { rr.evtid = QOS_L3_MBM_TOTAL_EVENT_ID; __mon_event_count(rmid, &rr); } if (is_mbm_local_enabled()) { rr.evtid = QOS_L3_MBM_LOCAL_EVENT_ID; __mon_event_count(rmid, &rr); /* * Call the MBA software controller only for the * control groups and when user has enabled * the software controller explicitly. */ if (is_mba_sc(NULL)) mbm_bw_count(rmid, &rr); } } /* * Handler to scan the limbo list and move the RMIDs * to free list whose occupancy < threshold_occupancy. */ void cqm_handle_limbo(struct work_struct *work) { unsigned long delay = msecs_to_jiffies(CQM_LIMBOCHECK_INTERVAL); int cpu = smp_processor_id(); struct rdt_resource *r; struct rdt_domain *d; mutex_lock(&rdtgroup_mutex); r = &rdt_resources_all[RDT_RESOURCE_L3]; d = container_of(work, struct rdt_domain, cqm_limbo.work); __check_limbo(d, false); if (has_busy_rmid(r, d)) schedule_delayed_work_on(cpu, &d->cqm_limbo, delay); mutex_unlock(&rdtgroup_mutex); } void cqm_setup_limbo_handler(struct rdt_domain *dom, unsigned long delay_ms) { unsigned long delay = msecs_to_jiffies(delay_ms); int cpu; cpu = cpumask_any(&dom->cpu_mask); dom->cqm_work_cpu = cpu; schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay); } void mbm_handle_overflow(struct work_struct *work) { unsigned long delay = msecs_to_jiffies(MBM_OVERFLOW_INTERVAL); struct rdtgroup *prgrp, *crgrp; int cpu = smp_processor_id(); struct list_head *head; struct rdt_resource *r; struct rdt_domain *d; mutex_lock(&rdtgroup_mutex); if (!static_branch_likely(&rdt_mon_enable_key)) goto out_unlock; r = &rdt_resources_all[RDT_RESOURCE_L3]; d = container_of(work, struct rdt_domain, mbm_over.work); list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) { mbm_update(r, d, prgrp->mon.rmid); head = &prgrp->mon.crdtgrp_list; list_for_each_entry(crgrp, head, mon.crdtgrp_list) mbm_update(r, d, crgrp->mon.rmid); if (is_mba_sc(NULL)) update_mba_bw(prgrp, d); } schedule_delayed_work_on(cpu, &d->mbm_over, delay); out_unlock: mutex_unlock(&rdtgroup_mutex); } void mbm_setup_overflow_handler(struct rdt_domain *dom, unsigned long delay_ms) { unsigned long delay = msecs_to_jiffies(delay_ms); int cpu; if (!static_branch_likely(&rdt_mon_enable_key)) return; cpu = cpumask_any(&dom->cpu_mask); dom->mbm_work_cpu = cpu; schedule_delayed_work_on(cpu, &dom->mbm_over, delay); } static int dom_data_init(struct rdt_resource *r) { struct rmid_entry *entry = NULL; int i, nr_rmids; nr_rmids = r->num_rmid; rmid_ptrs = kcalloc(nr_rmids, sizeof(struct rmid_entry), GFP_KERNEL); if (!rmid_ptrs) return -ENOMEM; for (i = 0; i < nr_rmids; i++) { entry = &rmid_ptrs[i]; INIT_LIST_HEAD(&entry->list); entry->rmid = i; list_add_tail(&entry->list, &rmid_free_lru); } /* * RMID 0 is special and is always allocated. It's used for all * tasks that are not monitored. */ entry = __rmid_entry(0); list_del(&entry->list); return 0; } static struct mon_evt llc_occupancy_event = { .name = "llc_occupancy", .evtid = QOS_L3_OCCUP_EVENT_ID, }; static struct mon_evt mbm_total_event = { .name = "mbm_total_bytes", .evtid = QOS_L3_MBM_TOTAL_EVENT_ID, }; static struct mon_evt mbm_local_event = { .name = "mbm_local_bytes", .evtid = QOS_L3_MBM_LOCAL_EVENT_ID, }; /* * Initialize the event list for the resource. * * Note that MBM events are also part of RDT_RESOURCE_L3 resource * because as per the SDM the total and local memory bandwidth * are enumerated as part of L3 monitoring. */ static void l3_mon_evt_init(struct rdt_resource *r) { INIT_LIST_HEAD(&r->evt_list); if (is_llc_occupancy_enabled()) list_add_tail(&llc_occupancy_event.list, &r->evt_list); if (is_mbm_total_enabled()) list_add_tail(&mbm_total_event.list, &r->evt_list); if (is_mbm_local_enabled()) list_add_tail(&mbm_local_event.list, &r->evt_list); } int rdt_get_mon_l3_config(struct rdt_resource *r) { unsigned int mbm_offset = boot_cpu_data.x86_cache_mbm_width_offset; unsigned int cl_size = boot_cpu_data.x86_cache_size; int ret; r->mon_scale = boot_cpu_data.x86_cache_occ_scale; r->num_rmid = boot_cpu_data.x86_cache_max_rmid + 1; r->mbm_width = MBM_CNTR_WIDTH_BASE; if (mbm_offset > 0 && mbm_offset <= MBM_CNTR_WIDTH_OFFSET_MAX) r->mbm_width += mbm_offset; else if (mbm_offset > MBM_CNTR_WIDTH_OFFSET_MAX) pr_warn("Ignoring impossible MBM counter offset\n"); /* * A reasonable upper limit on the max threshold is the number * of lines tagged per RMID if all RMIDs have the same number of * lines tagged in the LLC. * * For a 35MB LLC and 56 RMIDs, this is ~1.8% of the LLC. */ resctrl_cqm_threshold = cl_size * 1024 / r->num_rmid; /* h/w works in units of "boot_cpu_data.x86_cache_occ_scale" */ resctrl_cqm_threshold /= r->mon_scale; ret = dom_data_init(r); if (ret) return ret; l3_mon_evt_init(r); r->mon_capable = true; r->mon_enabled = true; return 0; } void __init intel_rdt_mbm_apply_quirk(void) { int cf_index; cf_index = (boot_cpu_data.x86_cache_max_rmid + 1) / 8 - 1; if (cf_index >= ARRAY_SIZE(mbm_cf_table)) { pr_info("No MBM correction factor available\n"); return; } mbm_cf_rmidthreshold = mbm_cf_table[cf_index].rmidthreshold; mbm_cf = mbm_cf_table[cf_index].cf; }