path: root/arch/x86/kernel/cpu/resctrl/monitor.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Resource Director Technology(RDT)
 * - Monitoring code
 *
 * Copyright (C) 2017 Intel Corporation
 *
 * Author:
 *    Vikas Shivappa <vikas.shivappa@intel.com>
 *
 * 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.
 */

#define pr_fmt(fmt)	"resctrl: " fmt

#include <linux/cpu.h>
#include <linux/module.h>
#include <linux/sizes.h>
#include <linux/slab.h>

#include <asm/cpu_device_id.h>
#include <asm/resctrl.h>

#include "internal.h"
#include "trace.h"

/**
 * struct rmid_entry - dirty tracking for all RMID.
 * @closid:	The CLOSID for this entry.
 * @rmid:	The RMID for this entry.
 * @busy:	The number of domains with cached data using this RMID.
 * @list:	Member of the rmid_free_lru list when busy == 0.
 *
 * Depending on the architecture the correct monitor is accessed using
 * both @closid and @rmid, or @rmid only.
 *
 * Take the rdtgroup_mutex when accessing.
 */
struct rmid_entry {
	u32				closid;
	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);

/*
 * @closid_num_dirty_rmid    The number of dirty RMID each CLOSID has.
 *     Only allocated when CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID is defined.
 *     Indexed by CLOSID. Protected by rdtgroup_mutex.
 */
static u32 *closid_num_dirty_rmid;

/*
 * @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 > resctrl_rmid_realloc_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 in bytes at which we will consider an
 * RMID available for re-allocation.
 */
unsigned int resctrl_rmid_realloc_threshold;

/*
 * This is the maximum value for the reallocation threshold, in bytes.
 */
unsigned int resctrl_rmid_realloc_limit;

#define CF(cf)	((unsigned long)(1048576 * (cf) + 0.5))

static int snc_nodes_per_l3_cache = 1;

/*
 * The correction factor table is documented in Documentation/arch/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