// SPDX-License-Identifier: GPL-2.0-only
/*
 * User interface for Resource Allocation in Resource Director Technology(RDT)
 *
 * Copyright (C) 2016 Intel Corporation
 *
 * Author: Fenghua Yu <fenghua.yu@intel.com>
 *
 * More information about RDT be found in the Intel (R) x86 Architecture
 * Software Developer Manual.
 */

#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt

#include <linux/cpu.h>
#include <linux/debugfs.h>
#include <linux/fs.h>
#include <linux/fs_parser.h>
#include <linux/sysfs.h>
#include <linux/kernfs.h>
#include <linux/once.h>
#include <linux/resctrl.h>
#include <linux/seq_buf.h>
#include <linux/seq_file.h>
#include <linux/sched/task.h>
#include <linux/slab.h>
#include <linux/user_namespace.h>

#include <uapi/linux/magic.h>

#include "internal.h"

/* Mutex to protect rdtgroup access. */
DEFINE_MUTEX(rdtgroup_mutex);

static struct kernfs_root *rdt_root;

struct rdtgroup rdtgroup_default;

LIST_HEAD(rdt_all_groups);

/* list of entries for the schemata file */
LIST_HEAD(resctrl_schema_all);

/*
 * List of struct mon_data containing private data of event files for use by
 * rdtgroup_mondata_show(). Protected by rdtgroup_mutex.
 */
static LIST_HEAD(mon_data_kn_priv_list);

/* The filesystem can only be mounted once. */
bool resctrl_mounted;

/* Kernel fs node for "info" directory under root */
static struct kernfs_node *kn_info;

/* Kernel fs node for "mon_groups" directory under root */
static struct kernfs_node *kn_mongrp;

/* Kernel fs node for "mon_data" directory under root */
static struct kernfs_node *kn_mondata;

/*
 * Used to store the max resource name width to display the schemata names in
 * a tabular format.
 */
int max_name_width;

static struct seq_buf last_cmd_status;

static char last_cmd_status_buf[512];

static int rdtgroup_setup_root(struct rdt_fs_context *ctx);

static void rdtgroup_destroy_root(void);

struct dentry *debugfs_resctrl;

/*
 * Memory bandwidth monitoring event to use for the default CTRL_MON group
 * and each new CTRL_MON group created by the user.  Only relevant when
 * the filesystem is mounted with the "mba_MBps" option so it does not
 * matter that it remains uninitialized on systems that do not support
 * the "mba_MBps" option.
 */
enum resctrl_event_id mba_mbps_default_event;

static bool resctrl_debug;

void rdt_last_cmd_clear(void)
{
        lockdep_assert_held(&rdtgroup_mutex);
        seq_buf_clear(&last_cmd_status);
}

void rdt_last_cmd_puts(const char *s)
{
        lockdep_assert_held(&rdtgroup_mutex);
        seq_buf_puts(&last_cmd_status, s);
}

void rdt_last_cmd_printf(const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        lockdep_assert_held(&rdtgroup_mutex);
        seq_buf_vprintf(&last_cmd_status, fmt, ap);
        va_end(ap);
}

void rdt_staged_configs_clear(void)
{
        struct rdt_ctrl_domain *dom;
        struct rdt_resource *r;

        lockdep_assert_held(&rdtgroup_mutex);

        for_each_alloc_capable_rdt_resource(r) {
                list_for_each_entry(dom, &r->ctrl_domains, hdr.list)
                        memset(dom->staged_config, 0, sizeof(dom->staged_config));
        }
}

static bool resctrl_is_mbm_enabled(void)
{
        return (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID) ||
                resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID));
}

/*
 * Trivial allocator for CLOSIDs. Use BITMAP APIs to manipulate a bitmap
 * of free CLOSIDs.
 *
 * Using a global CLOSID across all resources has some advantages and
 * some drawbacks:
 * + We can simply set current's closid to assign a task to a resource
 *   group.
 * + Context switch code can avoid extra memory references deciding which
 *   CLOSID to load into the PQR_ASSOC MSR
 * - We give up some options in configuring resource groups across multi-socket
 *   systems.
 * - Our choices on how to configure each resource become progressively more
 *   limited as the number of resources grows.
 */
static unsigned long *closid_free_map;

static int closid_free_map_len;

int closids_supported(void)
{
        return closid_free_map_len;
}

static int closid_init(void)
{
        struct resctrl_schema *s;
        u32 rdt_min_closid = ~0;

        /* Monitor only platforms still call closid_init() */
        if (list_empty(&resctrl_schema_all))
                return 0;

        /* Compute rdt_min_closid across all resources */
        list_for_each_entry(s, &resctrl_schema_all, list)
                rdt_min_closid = min(rdt_min_closid, s->num_closid);

        closid_free_map = bitmap_alloc(rdt_min_closid, GFP_KERNEL);
        if (!closid_free_map)
                return -ENOMEM;
        bitmap_fill(closid_free_map, rdt_min_closid);

        /* RESCTRL_RESERVED_CLOSID is always reserved for the default group */
        __clear_bit(RESCTRL_RESERVED_CLOSID, closid_free_map);
        closid_free_map_len = rdt_min_closid;

        return 0;
}

static void closid_exit(void)
{
        bitmap_free(closid_free_map);
        closid_free_map = NULL;
}

static int closid_alloc(void)
{
        int cleanest_closid;
        u32 closid;

        lockdep_assert_held(&rdtgroup_mutex);

        if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID) &&
            resctrl_is_mon_event_enabled(QOS_L3_OCCUP_EVENT_ID)) {
                cleanest_closid = resctrl_find_cleanest_closid();
                if (cleanest_closid < 0)
                        return cleanest_closid;
                closid = cleanest_closid;
        } else {
                closid = find_first_bit(closid_free_map, closid_free_map_len);
                if (closid == closid_free_map_len)
                        return -ENOSPC;
        }
        __clear_bit(closid, closid_free_map);

        return closid;
}

void closid_free(int closid)
{
        lockdep_assert_held(&rdtgroup_mutex);

        __set_bit(closid, closid_free_map);
}

/**
 * closid_allocated - test if provided closid is in use
 * @closid: closid to be tested
 *
 * Return: true if @closid is currently associated with a resource group,
 * false if @closid is free
 */
bool closid_allocated(unsigned int closid)
{
        lockdep_assert_held(&rdtgroup_mutex);

        return !test_bit(closid, closid_free_map);
}

bool closid_alloc_fixed(u32 closid)
{
        return __test_and_clear_bit(closid, closid_free_map);
}

/**
 * rdtgroup_mode_by_closid - Return mode of resource group with closid
 * @closid: closid if the resource group
 *
 * Each resource group is associated with a @closid. Here the mode
 * of a resource group can be queried by searching for it using its closid.
 *
 * Return: mode as &enum rdtgrp_mode of resource group with closid @closid
 */
enum rdtgrp_mode rdtgroup_mode_by_closid(int closid)
{
        struct rdtgroup *rdtgrp;

        list_for_each_entry(rdtgrp, &rdt_all_groups, rdtgroup_list) {
                if (rdtgrp->closid == closid)
                        return rdtgrp->mode;
        }

        return RDT_NUM_MODES;
}

static const char * const rdt_mode_str[] = {
        [RDT_MODE_SHAREABLE]            = "shareable",
        [RDT_MODE_EXCLUSIVE]            = "exclusive",
        [RDT_MODE_PSEUDO_LOCKSETUP]     = "pseudo-locksetup",
        [RDT_MODE_PSEUDO_LOCKED]        = "pseudo-locked",
};

/**
 * rdtgroup_mode_str - Return the string representation of mode
 * @mode: the resource group mode as &enum rdtgroup_mode
 *
 * Return: string representation of valid mode, "unknown" otherwise
 */
static const char *rdtgroup_mode_str(enum rdtgrp_mode mode)
{
        if (mode < RDT_MODE_SHAREABLE || mode >= RDT_NUM_MODES)
                return "unknown";

        return rdt_mode_str[mode];
}

/* set uid and gid of rdtgroup dirs and files to that of the creator */
static int rdtgroup_kn_set_ugid(struct kernfs_node *kn)
{
        struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID,
                                .ia_uid = current_fsuid(),
                                .ia_gid = current_fsgid(), };

        if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) &&
            gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID))
                return 0;

        return kernfs_setattr(kn, &iattr);
}

static int rdtgroup_add_file(struct kernfs_node *parent_kn, struct rftype *rft)
{
        struct kernfs_node *kn;
        int ret;

        kn = __kernfs_create_file(parent_kn, rft->name, rft->mode,
                                  GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
                                  0, rft->kf_ops, rft, NULL, NULL);
        if (IS_ERR(kn))
                return PTR_ERR(kn);

        ret = rdtgroup_kn_set_ugid(kn);
        if (ret) {
                kernfs_remove(kn);
                return ret;
        }

        return 0;
}

static int rdtgroup_seqfile_show(struct seq_file *m, void *arg)
{
        struct kernfs_open_file *of = m->private;
        struct rftype *rft = of->kn->priv;

        if (rft->seq_show)
                return rft->seq_show(of, m, arg);
        return 0;
}

static ssize_t rdtgroup_file_write(struct kernfs_open_file *of, char *buf,
                                   size_t nbytes, loff_t off)
{
        struct rftype *rft = of->kn->priv;

        if (rft->write)
                return rft->write(of, buf, nbytes, off);

        return -EINVAL;
}

static const struct kernfs_ops rdtgroup_kf_single_ops = {
        .atomic_write_len       = PAGE_SIZE,
        .write                  = rdtgroup_file_write,
        .seq_show               = rdtgroup_seqfile_show,
};

static const struct kernfs_ops kf_mondata_ops = {
        .atomic_write_len       = PAGE_SIZE,
        .seq_show               = rdtgroup_mondata_show,
};

static bool is_cpu_list(struct kernfs_open_file *of)
{
        struct rftype *rft = of->kn->priv;

        return rft->flags & RFTYPE_FLAGS_CPUS_LIST;
}

static int rdtgroup_cpus_show(struct kernfs_open_file *of,
                              struct seq_file *s, void *v)
{
        struct rdtgroup *rdtgrp;
        struct cpumask *mask;
        int ret = 0;

        rdtgrp = rdtgroup_kn_lock_live(of->kn);

        if (rdtgrp) {
                if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
                        if (!rdtgrp->plr->d) {
                                rdt_last_cmd_clear();
                                rdt_last_cmd_puts("Cache domain offline\n");
                                ret = -ENODEV;
                        } else {
                                mask = &rdtgrp->plr->d->hdr.cpu_mask;
                                seq_printf(s, is_cpu_list(of) ?
                                           "%*pbl\n" : "%*pb\n",
                                           cpumask_pr_args(mask));
                        }
                } else {
                        seq_printf(s, is_cpu_list(of) ? "%*pbl\n" : "%*pb\n",
                                   cpumask_pr_args(&rdtgrp->cpu_mask));
                }
        } else {
                ret = -ENOENT;
        }
        rdtgroup_kn_unlock(of->kn);

        return ret;
}

/*
 * Update the PGR_ASSOC MSR on all cpus in @cpu_mask,
 *
 * Per task closids/rmids must have been set up before calling this function.
 * @r may be NULL.
 */
static void
update_closid_rmid(const struct cpumask *cpu_mask, struct rdtgroup *r)
{
        struct resctrl_cpu_defaults defaults, *p = NULL;

        if (r) {
                defaults.closid = r->closid;
                defaults.rmid = r->mon.rmid;
                p = &defaults;
        }

        on_each_cpu_mask(cpu_mask, resctrl_arch_sync_cpu_closid_rmid, p, 1);
}

static int cpus_mon_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,
                          cpumask_var_t tmpmask)
{
        struct rdtgroup *prgrp = rdtgrp->mon.parent, *crgrp;
        struct list_head *head;

        /* Check whether cpus belong to parent ctrl group */
        cpumask_andnot(tmpmask, newmask, &prgrp->cpu_mask);
        if (!cpumask_empty(tmpmask)) {
                rdt_last_cmd_puts("Can only add CPUs to mongroup that belong to parent\n");
                return -EINVAL;
        }

        /* Check whether cpus are dropped from this group */
        cpumask_andnot(tmpmask, &rdtgrp->cpu_mask, newmask);
        if (!cpumask_empty(tmpmask)) {
                /* Give any dropped cpus to parent rdtgroup */
                cpumask_or(&prgrp->cpu_mask, &prgrp->cpu_mask, tmpmask);
                update_closid_rmid(tmpmask, prgrp);
        }

        /*
         * If we added cpus, remove them from previous group that owned them
         * and update per-cpu rmid
         */
        cpumask_andnot(tmpmask, newmask, &rdtgrp->cpu_mask);
        if (!cpumask_empty(tmpmask)) {
                head = &prgrp->mon.crdtgrp_list;
                list_for_each_entry(crgrp, head, mon.crdtgrp_list) {
                        if (crgrp == rdtgrp)
                                continue;
                        cpumask_andnot(&crgrp->cpu_mask, &crgrp->cpu_mask,
                                       tmpmask);
                }
                update_closid_rmid(tmpmask, rdtgrp);
        }

        /* Done pushing/pulling - update this group with new mask */
        cpumask_copy(&rdtgrp->cpu_mask, newmask);

        return 0;
}

static void cpumask_rdtgrp_clear(struct rdtgroup *r, struct cpumask *m)
{
        struct rdtgroup *crgrp;

        cpumask_andnot(&r->cpu_mask, &r->cpu_mask, m);
        /* update the child mon group masks as well*/
        list_for_each_entry(crgrp, &r->mon.crdtgrp_list, mon.crdtgrp_list)
                cpumask_and(&crgrp->cpu_mask, &r->cpu_mask, &crgrp->cpu_mask);
}

static int cpus_ctrl_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,
                           cpumask_var_t tmpmask, cpumask_var_t tmpmask1)
{
        struct rdtgroup *r, *crgrp;
        struct list_head *head;

        /* Check whether cpus are dropped from this group */
        cpumask_andnot(tmpmask, &rdtgrp->cpu_mask, newmask);
        if (!cpumask_empty(tmpmask)) {
                /* Can't drop from default group */
                if (rdtgrp == &rdtgroup_default) {
                        rdt_last_cmd_puts("Can't drop CPUs from default group\n");
                        return -EINVAL;
                }

                /* Give any dropped cpus to rdtgroup_default */
                cpumask_or(&rdtgroup_default.cpu_mask,
                           &rdtgroup_default.cpu_mask, tmpmask);
                update_closid_rmid(tmpmask, &rdtgroup_default);
        }

        /*
         * If we added cpus, remove them from previous group and
         * the prev group's child groups that owned them
         * and update per-cpu closid/rmid.
         */
        cpumask_andnot(tmpmask, newmask, &rdtgrp->cpu_mask);
        if (!cpumask_empty(tmpmask)) {
                list_for_each_entry(r, &rdt_all_groups, rdtgroup_list) {
                        if (r == rdtgrp)
                                continue;
                        cpumask_and(tmpmask1, &r->cpu_mask, tmpmask);
                        if (!cpumask_empty(tmpmask1))
                                cpumask_rdtgrp_clear(r, tmpmask1);
                }
                update_closid_rmid(tmpmask, rdtgrp);
        }

        /* Done pushing/pulling - update this group with new mask */
        cpumask_copy(&rdtgrp->cpu_mask, newmask);

        /*
         * Clear child mon group masks since there is a new parent mask
         * now and update the rmid for the cpus the child lost.
         */
        head = &rdtgrp->mon.crdtgrp_list;
        list_for_each_entry(crgrp, head, mon.crdtgrp_list) {
                cpumask_and(tmpmask, &rdtgrp->cpu_mask, &crgrp->cpu_mask);
                update_closid_rmid(tmpmask, rdtgrp);
                cpumask_clear(&crgrp->cpu_mask);
        }

        return 0;
}

static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
                                   char *buf, size_t nbytes, loff_t off)
{
        cpumask_var_t tmpmask, newmask, tmpmask1;
        struct rdtgroup *rdtgrp;
        int ret;

        if (!buf)
                return -EINVAL;

        if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL))
                return -ENOMEM;
        if (!zalloc_cpumask_var(&newmask, GFP_KERNEL)) {
                free_cpumask_var(tmpmask);
                return -ENOMEM;
        }
        if (!zalloc_cpumask_var(&tmpmask1, GFP_KERNEL)) {
                free_cpumask_var(tmpmask);
                free_cpumask_var(newmask);
                return -ENOMEM;
        }

        rdtgrp = rdtgroup_kn_lock_live(of->kn);
        if (!rdtgrp) {
                ret = -ENOENT;
                goto unlock;
        }

        rdt_last_cmd_clear();

        if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED ||
            rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
                ret = -EINVAL;
                rdt_last_cmd_puts("Pseudo-locking in progress\n");
                goto unlock;
        }

        if (is_cpu_list(of))
                ret = cpulist_parse(buf, newmask);
        else
                ret = cpumask_parse(buf, newmask);

        if (ret) {
                rdt_last_cmd_puts("Bad CPU list/mask\n");
                goto unlock;
        }

        /* check that user didn't specify any offline cpus */
        cpumask_andnot(tmpmask, newmask, cpu_online_mask);
        if (!cpumask_empty(tmpmask)) {
                ret = -EINVAL;
                rdt_last_cmd_puts("Can only assign online CPUs\n");
                goto unlock;
        }

        if (rdtgrp->type == RDTCTRL_GROUP)
                ret = cpus_ctrl_write(rdtgrp, newmask, tmpmask, tmpmask1);
        else if (rdtgrp->type == RDTMON_GROUP)
                ret = cpus_mon_write(rdtgrp, newmask, tmpmask);
        else
                ret = -EINVAL;

unlock:
        rdtgroup_kn_unlock(of->kn);
        free_cpumask_var(tmpmask);
        free_cpumask_var(newmask);
        free_cpumask_var(tmpmask1);

        return ret ?: nbytes;
}

/**
 * rdtgroup_remove - the helper to remove resource group safely
 * @rdtgrp: resource group to remove
 *
 * On resource group creation via a mkdir, an extra kernfs_node reference is
 * taken to ensure that the rdtgroup structure remains accessible for the
 * rdtgroup_kn_unlock() calls where it is removed.
 *
 * Drop the extra reference here, then free the rdtgroup structure.
 *
 * Return: void
 */
static void rdtgroup_remove(struct rdtgroup *rdtgrp)
{
        kernfs_put(rdtgrp->kn);
        kfree(rdtgrp);
}

static void _update_task_closid_rmid(void *task)
{
        /*
         * If the task is still current on this CPU, update PQR_ASSOC MSR.
         * Otherwise, the MSR is updated when the task is scheduled in.
         */
        if (task == current)
                resctrl_arch_sched_in(task);
}

static void update_task_closid_rmid(struct task_struct *t)
{
        if (IS_ENABLED(CONFIG_SMP) && task_curr(t))
                smp_call_function_single(task_cpu(t), _update_task_closid_rmid, t, 1);
        else
                _update_task_closid_rmid(t);
}

static bool task_in_rdtgroup(struct task_struct *tsk, struct rdtgroup *rdtgrp)
{
        u32 closid, rmid = rdtgrp->mon.rmid;

        if (rdtgrp->type == RDTCTRL_GROUP)
                closid = rdtgrp->closid;
        else if (rdtgrp->type == RDTMON_GROUP)
                closid = rdtgrp->mon.parent->closid;
        else
                return false;

        return resctrl_arch_match_closid(tsk, closid) &&
               resctrl_arch_match_rmid(tsk, closid, rmid);
}

static int __rdtgroup_move_task(struct task_struct *tsk,
                                struct rdtgroup *rdtgrp)
{
        /* If the task is already in rdtgrp, no need to move the task. */
        if (task_in_rdtgroup(tsk, rdtgrp))
                return 0;

        /*
         * Set the task's closid/rmid before the PQR_ASSOC MSR can be
         * updated by them.
         *
         * For ctrl_mon groups, move both closid and rmid.
         * For monitor groups, can move the tasks only from
         * their parent CTRL group.
         */
        if (rdtgrp->type == RDTMON_GROUP &&
            !resctrl_arch_match_closid(tsk, rdtgrp->mon.parent->closid)) {
                rdt_last_cmd_puts("Can't move task to different control group\n");
                return -EINVAL;
        }

        if (rdtgrp->type == RDTMON_GROUP)
                resctrl_arch_set_closid_rmid(tsk, rdtgrp->mon.parent->closid,
                                             rdtgrp->mon.rmid);
        else
                resctrl_arch_set_closid_rmid(tsk, rdtgrp->closid,
                                             rdtgrp->mon.rmid);

        /*
         * Ensure the task's closid and rmid are written before determining if
         * the task is current that will decide if it will be interrupted.
         * This pairs with the full barrier between the rq->curr update and
         * resctrl_arch_sched_in() during context switch.
         */
        smp_mb();

        /*
         * By now, the task's closid and rmid are set. If the task is current
         * on a CPU, the PQR_ASSOC MSR needs to be updated to make the resource
         * group go into effect. If the task is not current, the MSR will be
         * updated when the task is scheduled in.
         */
        update_task_closid_rmid(tsk);

        return 0;
}

static bool is_closid_match(struct task_struct *t, struct rdtgroup *r)
{
        return (resctrl_arch_alloc_capable() && (r->type == RDTCTRL_GROUP) &&
                resctrl_arch_match_closid(t, r->closid));
}

static bool is_rmid_match(struct task_struct *t, struct rdtgroup *r)
{
        return (resctrl_arch_mon_capable() && (r->type == RDTMON_GROUP) &&
                resctrl_arch_match_rmid(t, r->mon.parent->closid,
                                        r->mon.rmid));
}

/**
 * rdtgroup_tasks_assigned - Test if tasks have been assigned to resource group
 * @r: Resource group
 *
 * Return: 1 if tasks have been assigned to @r, 0 otherwise
 */
int rdtgroup_tasks_assigned(struct rdtgroup *r)
{
        struct task_struct *p, *t;
        int ret = 0;

        lockdep_assert_held(&rdtgroup_mutex);

        rcu_read_lock();
        for_each_process_thread(p, t) {
                if (is_closid_match(t, r) || is_rmid_match(t, r)) {
                        ret = 1;
                        break;
                }
        }
        rcu_read_unlock();

        return ret;
}

static int rdtgroup_task_write_permission(struct task_struct *task,
                                          struct kernfs_open_file *of)
{
        const struct cred *tcred = get_task_cred(task);
        const struct cred *cred = current_cred();
        int ret = 0;

        /*
         * Even if we're attaching all tasks in the thread group, we only
         * need to check permissions on one of them.
         */
        if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
            !uid_eq(cred->euid, tcred->uid) &&
            !uid_eq(cred->euid, tcred->suid)) {
                rdt_last_cmd_printf("No permission to move task %d\n", task->pid);
                ret = -EPERM;
        }

        put_cred(tcred);
        return ret;
}

static int rdtgroup_move_task(pid_t pid, struct rdtgroup *rdtgrp,
                              struct kernfs_open_file *of)
{
        struct task_struct *tsk;
        int ret;

        rcu_read_lock();
        if (pid) {
                tsk = find_task_by_vpid(pid);
                if (!tsk) {
                        rcu_read_unlock();
                        rdt_last_cmd_printf("No task %d\n", pid);
                        return -ESRCH;
                }
        } else {
                tsk = current;
        }

        get_task_struct(tsk);
        rcu_read_unlock();

        ret = rdtgroup_task_write_permission(tsk, of);
        if (!ret)
                ret = __rdtgroup_move_task(tsk, rdtgrp);

        put_task_struct(tsk);
        return ret;
}

static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
                                    char *buf, size_t nbytes, loff_t off)
{
        struct rdtgroup *rdtgrp;
        char *pid_str;
        int ret = 0;
        pid_t pid;

        rdtgrp = rdtgroup_kn_lock_live(of->kn);
        if (!rdtgrp) {
                rdtgroup_kn_unlock(of->kn);
                return -ENOENT;
        }
        rdt_last_cmd_clear();

        if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED ||
            rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
                ret = -EINVAL;
                rdt_last_cmd_puts("Pseudo-locking in progress\n");
                goto unlock;
        }

        while (buf && buf[0] != '\0' && buf[0] != '\n') {
                pid_str = strim(strsep(&buf, ","));

                if (kstrtoint(pid_str, 0, &pid)) {
                        rdt_last_cmd_printf("Task list parsing error pid %s\n", pid_str);
                        ret = -EINVAL;
                        break;
                }

                if (pid < 0) {
                        rdt_last_cmd_printf("Invalid pid %d\n", pid);
                        ret = -EINVAL;
                        break;
                }

                ret = rdtgroup_move_task(pid, rdtgrp, of);
                if (ret) {
                        rdt_last_cmd_printf("Error while processing task %d\n", pid);
                        break;
                }
        }

unlock:
        rdtgroup_kn_unlock(of->kn);

        return ret ?: nbytes;
}

static void show_rdt_tasks(struct rdtgroup *r, struct seq_file *s)
{
        struct task_struct *p, *t;
        pid_t pid;

        rcu_read_lock();
        for_each_process_thread(p, t) {
                if (is_closid_match(t, r) || is_rmid_match(t, r)) {
                        pid = task_pid_vnr(t);
                        if (pid)
                                seq_printf(s, "%d\n", pid);
                }
        }
        rcu_read_unlock();
}

static int rdtgroup_tasks_show(struct kernfs_open_file *of,
                               struct seq_file *s, void *v)
{
        struct rdtgroup *rdtgrp;
        int ret = 0;

        rdtgrp = rdtgroup_kn_lock_live(of->kn);
        if (rdtgrp)
                show_rdt_tasks(rdtgrp, s);
        else
                ret = -ENOENT;
        rdtgroup_kn_unlock(of->kn);

        return ret;
}

static int rdtgroup_closid_show(struct kernfs_open_file *of,
                                struct seq_file *s, void *v)
{
        struct rdtgroup *rdtgrp;
        int ret = 0;

        rdtgrp = rdtgroup_kn_lock_live(of->kn);
        if (rdtgrp)
                seq_printf(s, "%u\n", rdtgrp->closid);
        else
                ret = -ENOENT;
        rdtgroup_kn_unlock(of->kn);

        return ret;
}

static int rdtgroup_rmid_show(struct kernfs_open_file *of,
                              struct seq_file *s, void *v)
{
        struct rdtgroup *rdtgrp;
        int ret = 0;

        rdtgrp = rdtgroup_kn_lock_live(of->kn);
        if (rdtgrp)
                seq_printf(s, "%u\n", rdtgrp->mon.rmid);
        else
                ret = -ENOENT;
        rdtgroup_kn_unlock(of->kn);

        return ret;
}

#ifdef CONFIG_PROC_CPU_RESCTRL
/*
 * A task can only be part of one resctrl control group and of one monitor
 * group which is associated to that control group.
 *
 * 1)   res:
 *      mon:
 *
 *    resctrl is not available.
 *
 * 2)   res:/
 *      mon:
 *
 *    Task is part of the root resctrl control group, and it is not associated
 *    to any monitor group.
 *
 * 3)  res:/
 *     mon:mon0
 *
 *    Task is part of the root resctrl control group and monitor group mon0.
 *
 * 4)  res:group0
 *     mon:
 *
 *    Task is part of resctrl control group group0, and it is not associated
 *    to any monitor group.
 *
 * 5) res:group0
 *    mon:mon1
 *
 *    Task is part of resctrl control group group0 and monitor group mon1.
 */
int proc_resctrl_show(struct seq_file *s, struct pid_namespace *ns,
                      struct pid *pid, struct task_struct *tsk)
{
        struct rdtgroup *rdtg;
        int ret = 0;

        mutex_lock(&rdtgroup_mutex);

        /* Return empty if resctrl has not been mounted. */
        if (!resctrl_mounted) {
                seq_puts(s, "res:\nmon:\n");
                goto unlock;
        }

        list_for_each_entry(rdtg, &rdt_all_groups, rdtgroup_list) {
                struct rdtgroup *crg;

                /*
                 * Task information is only relevant for shareable
                 * and exclusive groups.
                 */
                if (rdtg->mode != RDT_MODE_SHAREABLE &&
                    rdtg->mode != RDT_MODE_EXCLUSIVE)
                        continue;

                if (!resctrl_arch_match_closid(tsk, rdtg->closid))
                        continue;

                seq_printf(s, "res:%s%s\n", (rdtg == &rdtgroup_default) ? "/" : "",
                           rdt_kn_name(rdtg->kn));
                seq_puts(s, "mon:");
                list_for_each_entry(crg, &rdtg->mon.crdtgrp_list,
                                    mon.crdtgrp_list) {
                        if (!resctrl_arch_match_rmid(tsk, crg->mon.parent->closid,
                                                     crg->mon.rmid))
                                continue;
                        seq_printf(s, "%s", rdt_kn_name(crg->kn));
                        break;
                }
                seq_putc(s, '\n');
                goto unlock;
        }
        /*
         * The above search should succeed. Otherwise return
         * with an error.
         */
        ret = -ENOENT;
unlock:
        mutex_unlock(&rdtgroup_mutex);

        return ret;
}
#endif

static int rdt_last_cmd_status_show(struct kernfs_open_file *of,
                                    struct seq_file *seq, void *v)
{
        int len;

        mutex_lock(&rdtgroup_mutex);
        len = seq_buf_used(&last_cmd_status);
        if (len)
                seq_printf(seq, "%.*s", len, last_cmd_status_buf);
        else
                seq_puts(seq, "ok\n");
        mutex_unlock(&rdtgroup_mutex);
        return 0;
}

void *rdt_kn_parent_priv(struct kernfs_node *kn)
{
        /*
         * The parent pointer is only valid within RCU section since it can be
         * replaced.
         */
        guard(rcu)();
        return rcu_dereference(kn->__parent)->priv;
}

static int rdt_num_closids_show(struct kernfs_open_file *of,
                                struct seq_file *seq, void *v)
{
        struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);

        seq_printf(seq, "%u\n", s->num_closid);
        return 0;
}

static int rdt_default_ctrl_show(struct kernfs_open_file *of,
                                 struct seq_file *seq, void *v)
{
        struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
        struct rdt_resource *r = s->res;

        seq_printf(seq, "%x\n", resctrl_get_default_ctrl(r));
        return 0;
}

static int rdt_min_cbm_bits_show(struct kernfs_open_file *of,
                                 struct seq_file *seq, void *v)
{
        struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
        struct rdt_resource *r = s->res;

        seq_printf(seq, "%u\n", r->cache.min_cbm_bits);
        return 0;
}

static int rdt_shareable_bits_show(struct kernfs_open_file *of,
                                   struct seq_file *seq, void *v)
{
        struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
        struct rdt_resource *r = s->res;

        seq_printf(seq, "%x\n", r->cache.shareable_bits);
        return 0;
}

/*
 * rdt_bit_usage_show - Display current usage of resources
 *
 * A domain is a shared resource that can now be allocated differently. Here
 * we display the current regions of the domain as an annotated bitmask.
 * For each domain of this resource its allocation bitmask
 * is annotated as below to indicate the current usage of the corresponding bit:
 *   0 - currently unused
 *   X - currently available for sharing and used by software and hardware
 *   H - currently used by hardware only but available for software use
 *   S - currently used and shareable by software only
 *   E - currently used exclusively by one resource group
 *   P - currently pseudo-locked by one resource group
 */
static int rdt_bit_usage_show(struct kernfs_open_file *of,
                              struct seq_file *seq, void *v)
{
        struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
        /*
         * Use unsigned long even though only 32 bits are used to ensure
         * test_bit() is used safely.
         */
        unsigned long sw_shareable = 0, hw_shareable = 0;
        unsigned long exclusive = 0, pseudo_locked = 0;
        struct rdt_resource *r = s->res;
        struct rdt_ctrl_domain *dom;
        int i, hwb, swb, excl, psl;
        enum rdtgrp_mode mode;
        bool sep = false;
        u32 ctrl_val;

        cpus_read_lock();
        mutex_lock(&rdtgroup_mutex);
        list_for_each_entry(dom, &r->ctrl_domains, hdr.list) {
                if (sep)
                        seq_putc(seq, ';');
                hw_shareable = r->cache.shareable_bits;
                sw_shareable = 0;
                exclusive = 0;
                seq_printf(seq, "%d=", dom->hdr.id);
                for (i = 0; i < closids_supported(); i++) {
                        if (!closid_allocated(i) ||
                            (resctrl_arch_get_io_alloc_enabled(r) &&
                             i == resctrl_io_alloc_closid(r)))
                                continue;
                        ctrl_val = resctrl_arch_get_config(r, dom, i,
                                                           s->conf_type);
                        mode = rdtgroup_mode_by_closid(i);
                        switch (mode) {
                        case RDT_MODE_SHAREABLE:
                                sw_shareable |= ctrl_val;
                                break;
                        case RDT_MODE_EXCLUSIVE:
                                exclusive |= ctrl_val;
                                break;
                        case RDT_MODE_PSEUDO_LOCKSETUP:
                        /*
                         * RDT_MODE_PSEUDO_LOCKSETUP is possible
                         * here but not included since the CBM
                         * associated with this CLOSID in this mode
                         * is not initialized and no task or cpu can be
                         * assigned this CLOSID.
                         */
                                break;
                        case RDT_MODE_PSEUDO_LOCKED:
                        case RDT_NUM_MODES:
                                WARN(1,
                                     "invalid mode for closid %d\n", i);
                                break;
                        }
                }

                /*
                 * When the "io_alloc" feature is enabled, a portion of the cache
                 * is configured for shared use between hardware and software.
                 * Also, when CDP is enabled the CBMs of CDP_CODE and CDP_DATA
                 * resources are kept in sync. So, the CBMs for "io_alloc" can
                 * be accessed through either resource.
                 */
                if (resctrl_arch_get_io_alloc_enabled(r)) {
                        ctrl_val = resctrl_arch_get_config(r, dom,
                                                           resctrl_io_alloc_closid(r),
                                                           s->conf_type);
                        hw_shareable |= ctrl_val;
                }

                for (i = r->cache.cbm_len - 1; i >= 0; i--) {
                        pseudo_locked = dom->plr ? dom->plr->cbm : 0;
                        hwb = test_bit(i, &hw_shareable);
                        swb = test_bit(i, &sw_shareable);
                        excl = test_bit(i, &exclusive);
                        psl = test_bit(i, &pseudo_locked);
                        if (hwb && swb)
                                seq_putc(seq, 'X');
                        else if (hwb && !swb)
                                seq_putc(seq, 'H');
                        else if (!hwb && swb)
                                seq_putc(seq, 'S');
                        else if (excl)
                                seq_putc(seq, 'E');
                        else if (psl)
                                seq_putc(seq, 'P');
                        else /* Unused bits remain */
                                seq_putc(seq, '0');
                }
                sep = true;
        }
        seq_putc(seq, '\n');
        mutex_unlock(&rdtgroup_mutex);
        cpus_read_unlock();
        return 0;
}

static int rdt_min_bw_show(struct kernfs_open_file *of,
                           struct seq_file *seq, void *v)
{
        struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
        struct rdt_resource *r = s->res;

        seq_printf(seq, "%u\n", r->membw.min_bw);
        return 0;
}

static int rdt_num_rmids_show(struct kernfs_open_file *of,
                              struct seq_file *seq, void *v)
{
        struct rdt_resource *r = rdt_kn_parent_priv(of->kn);

        seq_printf(seq, "%u\n", r->mon.num_rmid);

        return 0;
}

static int rdt_mon_features_show(struct kernfs_open_file *of,
                                 struct seq_file *seq, void *v)
{
        struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
        struct mon_evt *mevt;

        for_each_mon_event(mevt) {
                if (mevt->rid != r->rid || !mevt->enabled)
                        continue;
                seq_printf(seq, "%s\n", mevt->name);
                if (mevt->configurable &&
                    !resctrl_arch_mbm_cntr_assign_enabled(r))
                        seq_printf(seq, "%s_config\n", mevt->name);
        }

        return 0;
}

static int rdt_bw_gran_show(struct kernfs_open_file *of,
                            struct seq_file *seq, void *v)
{
        struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
        struct rdt_resource *r = s->res;

        seq_printf(seq, "%u\n", r->membw.bw_gran);
        return 0;
}

static int rdt_delay_linear_show(struct kernfs_open_file *of,
                                 struct seq_file *seq, void *v)
{
        struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
        struct rdt_resource *r = s->res;

        seq_printf(seq, "%u\n", r->membw.delay_linear);
        return 0;
}

static int max_threshold_occ_show(struct kernfs_open_file *of,
                                  struct seq_file *seq, void *v)
{
        seq_printf(seq, "%u\n", resctrl_rmid_realloc_threshold);

        return 0;
}

static int rdt_thread_throttle_mode_show(struct kernfs_open_file *of,
                                         struct seq_file *seq, void *v)
{
        struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
        struct rdt_resource *r = s->res;

        switch (r->membw.throttle_mode) {
        case THREAD_THROTTLE_PER_THREAD:
                seq_puts(seq, "per-thread\n");
                return 0;
        case THREAD_THROTTLE_MAX:
                seq_puts(seq, "max\n");
                return 0;
        case THREAD_THROTTLE_UNDEFINED:
                seq_puts(seq, "undefined\n");
                return 0;
        }

        WARN_ON_ONCE(1);

        return 0;
}

static ssize_t max_threshold_occ_write(struct kernfs_open_file *of,
                                       char *buf, size_t nbytes, loff_t off)
{
        unsigned int bytes;
        int ret;

        ret = kstrtouint(buf, 0, &bytes);
        if (ret)
                return ret;

        if (bytes > resctrl_rmid_realloc_limit)
                return -EINVAL;

        resctrl_rmid_realloc_threshold = resctrl_arch_round_mon_val(bytes);

        return nbytes;
}

/*
 * rdtgroup_mode_show - Display mode of this resource group
 */
static int rdtgroup_mode_show(struct kernfs_open_file *of,
                              struct seq_file *s, void *v)
{
        struct rdtgroup *rdtgrp;

        rdtgrp = rdtgroup_kn_lock_live(of->kn);
        if (!rdtgrp) {
                rdtgroup_kn_unlock(of->kn);
                return -ENOENT;
        }

        seq_printf(s, "%s\n", rdtgroup_mode_str(rdtgrp->mode));

        rdtgroup_kn_unlock(of->kn);
        return 0;
}

enum resctrl_conf_type resctrl_peer_type(enum resctrl_conf_type my_type)
{
        switch (my_type) {
        case CDP_CODE:
                return CDP_DATA;
        case CDP_DATA:
                return CDP_CODE;
        default:
        case CDP_NONE:
                return CDP_NONE;
        }
}

static int rdt_has_sparse_bitmasks_show(struct kernfs_open_file *of,
                                        struct seq_file *seq, void *v)
{
        struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
        struct rdt_resource *r = s->res;

        seq_printf(seq, "%u\n", r->cache.arch_has_sparse_bitmasks);

        return 0;
}

/**
 * __rdtgroup_cbm_overlaps - Does CBM for intended closid overlap with other
 * @r: Resource to which domain instance @d belongs.
 * @d: The domain instance for which @closid is being tested.
 * @cbm: Capacity bitmask being tested.
 * @closid: Intended closid for @cbm.
 * @type: CDP type of @r.
 * @exclusive: Only check if overlaps with exclusive resource groups
 *
 * Checks if provided @cbm intended to be used for @closid on domain
 * @d overlaps with any other closids or other hardware usage associated
 * with this domain. If @exclusive is true then only overlaps with
 * resource groups in exclusive mode will be considered. If @exclusive
 * is false then overlaps with any resource group or hardware entities
 * will be considered.
 *
 * @cbm is unsigned long, even if only 32 bits are used, to make the
 * bitmap functions work correctly.
 *
 * Return: false if CBM does not overlap, true if it does.
 */
static bool __rdtgroup_cbm_overlaps(struct rdt_resource *r, struct rdt_ctrl_domain *d,
                                    unsigned long cbm, int closid,
                                    enum resctrl_conf_type type, bool exclusive)
{
        enum rdtgrp_mode mode;
        unsigned long ctrl_b;
        int i;

        /* Check for any overlap with regions used by hardware directly */
        if (!exclusive) {
                ctrl_b = r->cache.shareable_bits;
                if (bitmap_intersects(&cbm, &ctrl_b, r->cache.cbm_len))
                        return true;
        }

        /* Check for overlap with other resource groups */
        for (i = 0; i < closids_supported(); i++) {
                ctrl_b = resctrl_arch_get_config(r, d, i, type);
                mode = rdtgroup_mode_by_closid(i);
                if (closid_allocated(i) && i != closid &&
                    mode != RDT_MODE_PSEUDO_LOCKSETUP) {
                        if (bitmap_intersects(&cbm, &ctrl_b, r->cache.cbm_len)) {
                                if (exclusive) {
                                        if (mode == RDT_MODE_EXCLUSIVE)
                                                return true;
                                        continue;
                                }
                                return true;
                        }
                }
        }

        return false;
}

/**
 * rdtgroup_cbm_overlaps - Does CBM overlap with other use of hardware
 * @s: Schema for the resource to which domain instance @d belongs.
 * @d: The domain instance for which @closid is being tested.
 * @cbm: Capacity bitmask being tested.
 * @closid: Intended closid for @cbm.
 * @exclusive: Only check if overlaps with exclusive resource groups
 *
 * Resources that can be allocated using a CBM can use the CBM to control
 * the overlap of these allocations. rdtgroup_cmb_overlaps() is the test
 * for overlap. Overlap test is not limited to the specific resource for
 * which the CBM is intended though - when dealing with CDP resources that
 * share the underlying hardware the overlap check should be performed on
 * the CDP resource sharing the hardware also.
 *
 * Refer to description of __rdtgroup_cbm_overlaps() for the details of the
 * overlap test.
 *
 * Return: true if CBM overlap detected, false if there is no overlap
 */
bool rdtgroup_cbm_overlaps(struct resctrl_schema *s, struct rdt_ctrl_domain *d,
                           unsigned long cbm, int closid, bool exclusive)
{
        enum resctrl_conf_type peer_type = resctrl_peer_type(s->conf_type);
        struct rdt_resource *r = s->res;

        if (__rdtgroup_cbm_overlaps(r, d, cbm, closid, s->conf_type,
                                    exclusive))
                return true;

        if (!resctrl_arch_get_cdp_enabled(r->rid))
                return false;
        return  __rdtgroup_cbm_overlaps(r, d, cbm, closid, peer_type, exclusive);
}

/**
 * rdtgroup_mode_test_exclusive - Test if this resource group can be exclusive
 * @rdtgrp: Resource group identified through its closid.
 *
 * An exclusive resource group implies that there should be no sharing of
 * its allocated resources. At the time this group is considered to be
 * exclusive this test can determine if its current schemata supports this
 * setting by testing for overlap with all other resource groups.
 *
 * Return: true if resource group can be exclusive, false if there is overlap
 * with allocations of other resource groups and thus this resource group
 * cannot be exclusive.
 */
static bool rdtgroup_mode_test_exclusive(struct rdtgroup *rdtgrp)
{
        int closid = rdtgrp->closid;
        struct rdt_ctrl_domain *d;
        struct resctrl_schema *s;
        struct rdt_resource *r;
        bool has_cache = false;
        u32 ctrl;

        /* Walking r->domains, ensure it can't race with cpuhp */
        lockdep_assert_cpus_held();

        list_for_each_entry(s, &resctrl_schema_all, list) {
                r = s->res;
                if (r->rid == RDT_RESOURCE_MBA || r->rid == RDT_RESOURCE_SMBA)
                        continue;
                has_cache = true;
                list_for_each_entry(d, &r->ctrl_domains, hdr.list) {
                        ctrl = resctrl_arch_get_config(r, d, closid,
                                                       s->conf_type);
                        if (rdtgroup_cbm_overlaps(s, d, ctrl, closid, false)) {
                                rdt_last_cmd_puts("Schemata overlaps\n");
                                return false;
                        }
                }
        }

        if (!has_cache) {
                rdt_last_cmd_puts("Cannot be exclusive without CAT/CDP\n");
                return false;
        }

        return true;
}

/*
 * rdtgroup_mode_write - Modify the resource group's mode
 */
static ssize_t rdtgroup_mode_write(struct kernfs_open_file *of,
                                   char *buf, size_t nbytes, loff_t off)
{
        struct rdtgroup *rdtgrp;
        enum rdtgrp_mode mode;
        int ret = 0;

        /* Valid input requires a trailing newline */
        if (nbytes == 0 || buf[nbytes - 1] != '\n')
                return -EINVAL;
        buf[nbytes - 1] = '\0';

        rdtgrp = rdtgroup_kn_lock_live(of->kn);
        if (!rdtgrp) {
                rdtgroup_kn_unlock(of->kn);
                return -ENOENT;
        }

        rdt_last_cmd_clear();

        mode = rdtgrp->mode;

        if ((!strcmp(buf, "shareable") && mode == RDT_MODE_SHAREABLE) ||
            (!strcmp(buf, "exclusive") && mode == RDT_MODE_EXCLUSIVE) ||
            (!strcmp(buf, "pseudo-locksetup") &&
             mode == RDT_MODE_PSEUDO_LOCKSETUP) ||
            (!strcmp(buf, "pseudo-locked") && mode == RDT_MODE_PSEUDO_LOCKED))
                goto out;

        if (mode == RDT_MODE_PSEUDO_LOCKED) {
                rdt_last_cmd_puts("Cannot change pseudo-locked group\n");
                ret = -EINVAL;
                goto out;
        }

        if (!strcmp(buf, "shareable")) {
                if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
                        ret = rdtgroup_locksetup_exit(rdtgrp);
                        if (ret)
                                goto out;
                }
                rdtgrp->mode = RDT_MODE_SHAREABLE;
        } else if (!strcmp(buf, "exclusive")) {
                if (!rdtgroup_mode_test_exclusive(rdtgrp)) {
                        ret = -EINVAL;
                        goto out;
                }
                if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
                        ret = rdtgroup_locksetup_exit(rdtgrp);
                        if (ret)
                                goto out;
                }
                rdtgrp->mode = RDT_MODE_EXCLUSIVE;
        } else if (IS_ENABLED(CONFIG_RESCTRL_FS_PSEUDO_LOCK) &&
                   !strcmp(buf, "pseudo-locksetup")) {
                ret = rdtgroup_locksetup_enter(rdtgrp);
                if (ret)
                        goto out;
                rdtgrp->mode = RDT_MODE_PSEUDO_LOCKSETUP;
        } else {
                rdt_last_cmd_puts("Unknown or unsupported mode\n");
                ret = -EINVAL;
        }

out:
        rdtgroup_kn_unlock(of->kn);
        return ret ?: nbytes;
}

/**
 * rdtgroup_cbm_to_size - Translate CBM to size in bytes
 * @r: RDT resource to which @d belongs.
 * @d: RDT domain instance.
 * @cbm: bitmask for which the size should be computed.
 *
 * The bitmask provided associated with the RDT domain instance @d will be
 * translated into how many bytes it represents. The size in bytes is
 * computed by first dividing the total cache size by the CBM length to
 * determine how many bytes each bit in the bitmask represents. The result
 * is multiplied with the number of bits set in the bitmask.
 *
 * @cbm is unsigned long, even if only 32 bits are used to make the
 * bitmap functions work correctly.
 */
unsigned int rdtgroup_cbm_to_size(struct rdt_resource *r,
                                  struct rdt_ctrl_domain *d, unsigned long cbm)
{
        unsigned int size = 0;
        struct cacheinfo *ci;
        int num_b;

        if (WARN_ON_ONCE(r->ctrl_scope != RESCTRL_L2_CACHE && r->ctrl_scope != RESCTRL_L3_CACHE))
                return size;

        num_b = bitmap_weight(&cbm, r->cache.cbm_len);
        ci = get_cpu_cacheinfo_level(cpumask_any(&d->hdr.cpu_mask), r->ctrl_scope);
        if (ci)
                size = ci->size / r->cache.cbm_len * num_b;

        return size;
}

bool is_mba_sc(struct rdt_resource *r)
{
        if (!r)
                r = resctrl_arch_get_resource(RDT_RESOURCE_MBA);

        /*
         * The software controller support is only applicable to MBA resource.
         * Make sure to check for resource type.
         */
        if (r->rid != RDT_RESOURCE_MBA)
                return false;

        return r->membw.mba_sc;
}

/*
 * rdtgroup_size_show - Display size in bytes of allocated regions
 *
 * The "size" file mirrors the layout of the "schemata" file, printing the
 * size in bytes of each region instead of the capacity bitmask.
 */
static int rdtgroup_size_show(struct kernfs_open_file *of,
                              struct seq_file *s, void *v)
{
        struct resctrl_schema *schema;
        enum resctrl_conf_type type;
        struct rdt_ctrl_domain *d;
        struct rdtgroup *rdtgrp;
        struct rdt_resource *r;
        unsigned int size;
        int ret = 0;
        u32 closid;
        bool sep;
        u32 ctrl;

        rdtgrp = rdtgroup_kn_lock_live(of->kn);
        if (!rdtgrp) {
                rdtgroup_kn_unlock(of->kn);
                return -ENOENT;
        }

        if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
                if (!rdtgrp->plr->d) {
                        rdt_last_cmd_clear();
                        rdt_last_cmd_puts("Cache domain offline\n");
                        ret = -ENODEV;
                } else {
                        seq_printf(s, "%*s:", max_name_width,
                                   rdtgrp->plr->s->name);
                        size = rdtgroup_cbm_to_size(rdtgrp->plr->s->res,
                                                    rdtgrp->plr->d,
                                                    rdtgrp->plr->cbm);
                        seq_printf(s, "%d=%u\n", rdtgrp->plr->d->hdr.id, size);
                }
                goto out;
        }

        closid = rdtgrp->closid;

        list_for_each_entry(schema, &resctrl_schema_all, list) {
                r = schema->res;
                type = schema->conf_type;
                sep = false;
                seq_printf(s, "%*s:", max_name_width, schema->name);
                list_for_each_entry(d, &r->ctrl_domains, hdr.list) {
                        if (sep)
                                seq_putc(s, ';');
                        if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
                                size = 0;
                        } else {
                                if (is_mba_sc(r))
                                        ctrl = d->mbps_val[closid];
                                else
                                        ctrl = resctrl_arch_get_config(r, d,
                                                                       closid,
                                                                       type);
                                if (r->rid == RDT_RESOURCE_MBA ||
                                    r->rid == RDT_RESOURCE_SMBA)
                                        size = ctrl;
                                else
                                        size = rdtgroup_cbm_to_size(r, d, ctrl);
                        }
                        seq_printf(s, "%d=%u", d->hdr.id, size);
                        sep = true;
                }
                seq_putc(s, '\n');
        }

out:
        rdtgroup_kn_unlock(of->kn);

        return ret;
}

static void mondata_config_read(struct resctrl_mon_config_info *mon_info)
{
        smp_call_function_any(&mon_info->d->hdr.cpu_mask,
                              resctrl_arch_mon_event_config_read, mon_info, 1);
}

static int mbm_config_show(struct seq_file *s, struct rdt_resource *r, u32 evtid)
{
        struct resctrl_mon_config_info mon_info;
        struct rdt_l3_mon_domain *dom;
        bool sep = false;

        cpus_read_lock();
        mutex_lock(&rdtgroup_mutex);

        list_for_each_entry(dom, &r->mon_domains, hdr.list) {
                if (sep)
                        seq_puts(s, ";");

                memset(&mon_info, 0, sizeof(struct resctrl_mon_config_info));
                mon_info.r = r;
                mon_info.d = dom;
                mon_info.evtid = evtid;
                mondata_config_read(&mon_info);

                seq_printf(s, "%d=0x%02x", dom->hdr.id, mon_info.mon_config);
                sep = true;
        }
        seq_puts(s, "\n");

        mutex_unlock(&rdtgroup_mutex);
        cpus_read_unlock();

        return 0;
}

static int mbm_total_bytes_config_show(struct kernfs_open_file *of,
                                       struct seq_file *seq, void *v)
{
        struct rdt_resource *r = rdt_kn_parent_priv(of->kn);

        mbm_config_show(seq, r, QOS_L3_MBM_TOTAL_EVENT_ID);

        return 0;
}

static int mbm_local_bytes_config_show(struct kernfs_open_file *of,
                                       struct seq_file *seq, void *v)
{
        struct rdt_resource *r = rdt_kn_parent_priv(of->kn);

        mbm_config_show(seq, r, QOS_L3_MBM_LOCAL_EVENT_ID);

        return 0;
}

static void mbm_config_write_domain(struct rdt_resource *r,
                                    struct rdt_l3_mon_domain *d, u32 evtid, u32 val)
{
        struct resctrl_mon_config_info mon_info = {0};

        /*
         * Read the current config value first. If both are the same then
         * no need to write it again.
         */
        mon_info.r = r;
        mon_info.d = d;
        mon_info.evtid = evtid;
        mondata_config_read(&mon_info);
        if (mon_info.mon_config == val)
                return;

        mon_info.mon_config = val;

        /*
         * Update MSR_IA32_EVT_CFG_BASE MSR on one of the CPUs in the
         * domain. The MSRs offset from MSR MSR_IA32_EVT_CFG_BASE
         * are scoped at the domain level. Writing any of these MSRs
         * on one CPU is observed by all the CPUs in the domain.
         */
        smp_call_function_any(&d->hdr.cpu_mask, resctrl_arch_mon_event_config_write,
                              &mon_info, 1);

        /*
         * When an Event Configuration is changed, the bandwidth counters
         * for all RMIDs and Events will be cleared by the hardware. The
         * hardware also sets MSR_IA32_QM_CTR.Unavailable (bit 62) for
         * every RMID on the next read to any event for every RMID.
         * Subsequent reads will have MSR_IA32_QM_CTR.Unavailable (bit 62)
         * cleared while it is tracked by the hardware. Clear the
         * mbm_local and mbm_total counts for all the RMIDs.
         */
        resctrl_arch_reset_rmid_all(r, d);
}

static int mon_config_write(struct rdt_resource *r, char *tok, u32 evtid)
{
        char *dom_str = NULL, *id_str;
        struct rdt_l3_mon_domain *d;
        unsigned long dom_id, val;

        /* Walking r->domains, ensure it can't race with cpuhp */
        lockdep_assert_cpus_held();

next:
        if (!tok || tok[0] == '\0')
                return 0;

        /* Start processing the strings for each domain */
        dom_str = strim(strsep(&tok, ";"));
        id_str = strsep(&dom_str, "=");

        if (!id_str || kstrtoul(id_str, 10, &dom_id)) {
                rdt_last_cmd_puts("Missing '=' or non-numeric domain id\n");
                return -EINVAL;
        }

        if (!dom_str || kstrtoul(dom_str, 16, &val)) {
                rdt_last_cmd_puts("Non-numeric event configuration value\n");
                return -EINVAL;
        }

        /* Value from user cannot be more than the supported set of events */
        if ((val & r->mon.mbm_cfg_mask) != val) {
                rdt_last_cmd_printf("Invalid event configuration: max valid mask is 0x%02x\n",
                                    r->mon.mbm_cfg_mask);
                return -EINVAL;
        }

        list_for_each_entry(d, &r->mon_domains, hdr.list) {
                if (d->hdr.id == dom_id) {
                        mbm_config_write_domain(r, d, evtid, val);
                        goto next;
                }
        }

        return -EINVAL;
}

static ssize_t mbm_total_bytes_config_write(struct kernfs_open_file *of,
                                            char *buf, size_t nbytes,
                                            loff_t off)
{
        struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
        int ret;

        /* Valid input requires a trailing newline */
        if (nbytes == 0 || buf[nbytes - 1] != '\n')
                return -EINVAL;

        cpus_read_lock();
        mutex_lock(&rdtgroup_mutex);

        rdt_last_cmd_clear();

        buf[nbytes - 1] = '\0';

        ret = mon_config_write(r, buf, QOS_L3_MBM_TOTAL_EVENT_ID);

        mutex_unlock(&rdtgroup_mutex);
        cpus_read_unlock();

        return ret ?: nbytes;
}

static ssize_t mbm_local_bytes_config_write(struct kernfs_open_file *of,
                                            char *buf, size_t nbytes,
                                            loff_t off)
{
        struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
        int ret;

        /* Valid input requires a trailing newline */
        if (nbytes == 0 || buf[nbytes - 1] != '\n')
                return -EINVAL;

        cpus_read_lock();
        mutex_lock(&rdtgroup_mutex);

        rdt_last_cmd_clear();

        buf[nbytes - 1] = '\0';

        ret = mon_config_write(r, buf, QOS_L3_MBM_LOCAL_EVENT_ID);

        mutex_unlock(&rdtgroup_mutex);
        cpus_read_unlock();

        return ret ?: nbytes;
}

/*
 * resctrl_bmec_files_show() — Controls the visibility of BMEC-related resctrl
 * files. When @show is true, the files are displayed; when false, the files
 * are hidden.
 * Don't treat kernfs_find_and_get failure as an error, since this function may
 * be called regardless of whether BMEC is supported or the event is enabled.
 */
void resctrl_bmec_files_show(struct rdt_resource *r, struct kernfs_node *l3_mon_kn,
                             bool show)
{
        struct kernfs_node *kn_config, *mon_kn = NULL;
        char name[32];

        if (!l3_mon_kn) {
                sprintf(name, "%s_MON", r->name);
                mon_kn = kernfs_find_and_get(kn_info, name);
                if (!mon_kn)
                        return;
                l3_mon_kn = mon_kn;
        }

        kn_config = kernfs_find_and_get(l3_mon_kn, "mbm_total_bytes_config");
        if (kn_config) {
                kernfs_show(kn_config, show);
                kernfs_put(kn_config);
        }

        kn_config = kernfs_find_and_get(l3_mon_kn, "mbm_local_bytes_config");
        if (kn_config) {
                kernfs_show(kn_config, show);
                kernfs_put(kn_config);
        }

        /* Release the reference only if it was acquired */
        if (mon_kn)
                kernfs_put(mon_kn);
}

const char *rdtgroup_name_by_closid(u32 closid)
{
        struct rdtgroup *rdtgrp;

        list_for_each_entry(rdtgrp, &rdt_all_groups, rdtgroup_list) {
                if (rdtgrp->closid == closid)
                        return rdt_kn_name(rdtgrp->kn);
        }

        return NULL;
}

/* rdtgroup information files for one cache resource. */
static struct rftype res_common_files[] = {
        {
                .name           = "last_cmd_status",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdt_last_cmd_status_show,
                .fflags         = RFTYPE_TOP_INFO,
        },
        {
                .name           = "mbm_assign_on_mkdir",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = resctrl_mbm_assign_on_mkdir_show,
                .write          = resctrl_mbm_assign_on_mkdir_write,
        },
        {
                .name           = "num_closids",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdt_num_closids_show,
                .fflags         = RFTYPE_CTRL_INFO,
        },
        {
                .name           = "mon_features",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdt_mon_features_show,
                .fflags         = RFTYPE_MON_INFO,
        },
        {
                .name           = "available_mbm_cntrs",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = resctrl_available_mbm_cntrs_show,
        },
        {
                .name           = "num_rmids",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdt_num_rmids_show,
                .fflags         = RFTYPE_MON_INFO,
        },
        {
                .name           = "cbm_mask",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdt_default_ctrl_show,
                .fflags         = RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE,
        },
        {
                .name           = "num_mbm_cntrs",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = resctrl_num_mbm_cntrs_show,
        },
        {
                .name           = "min_cbm_bits",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdt_min_cbm_bits_show,
                .fflags         = RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE,
        },
        {
                .name           = "shareable_bits",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdt_shareable_bits_show,
                .fflags         = RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE,
        },
        {
                .name           = "bit_usage",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdt_bit_usage_show,
                .fflags         = RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE,
        },
        {
                .name           = "min_bandwidth",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdt_min_bw_show,
                .fflags         = RFTYPE_CTRL_INFO | RFTYPE_RES_MB,
        },
        {
                .name           = "bandwidth_gran",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdt_bw_gran_show,
                .fflags         = RFTYPE_CTRL_INFO | RFTYPE_RES_MB,
        },
        {
                .name           = "delay_linear",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdt_delay_linear_show,
                .fflags         = RFTYPE_CTRL_INFO | RFTYPE_RES_MB,
        },
        /*
         * Platform specific which (if any) capabilities are provided by
         * thread_throttle_mode. Defer "fflags" initialization to platform
         * discovery.
         */
        {
                .name           = "thread_throttle_mode",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdt_thread_throttle_mode_show,
        },
        {
                .name           = "io_alloc",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = resctrl_io_alloc_show,
                .write          = resctrl_io_alloc_write,
        },
        {
                .name           = "io_alloc_cbm",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = resctrl_io_alloc_cbm_show,
                .write          = resctrl_io_alloc_cbm_write,
        },
        {
                .name           = "max_threshold_occupancy",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .write          = max_threshold_occ_write,
                .seq_show       = max_threshold_occ_show,
                .fflags         = RFTYPE_MON_INFO | RFTYPE_RES_CACHE,
        },
        {
                .name           = "mbm_total_bytes_config",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = mbm_total_bytes_config_show,
                .write          = mbm_total_bytes_config_write,
        },
        {
                .name           = "mbm_local_bytes_config",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = mbm_local_bytes_config_show,
                .write          = mbm_local_bytes_config_write,
        },
        {
                .name           = "event_filter",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = event_filter_show,
                .write          = event_filter_write,
        },
        {
                .name           = "mbm_L3_assignments",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = mbm_L3_assignments_show,
                .write          = mbm_L3_assignments_write,
        },
        {
                .name           = "mbm_assign_mode",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = resctrl_mbm_assign_mode_show,
                .write          = resctrl_mbm_assign_mode_write,
                .fflags         = RFTYPE_MON_INFO | RFTYPE_RES_CACHE,
        },
        {
                .name           = "cpus",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .write          = rdtgroup_cpus_write,
                .seq_show       = rdtgroup_cpus_show,
                .fflags         = RFTYPE_BASE,
        },
        {
                .name           = "cpus_list",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .write          = rdtgroup_cpus_write,
                .seq_show       = rdtgroup_cpus_show,
                .flags          = RFTYPE_FLAGS_CPUS_LIST,
                .fflags         = RFTYPE_BASE,
        },
        {
                .name           = "tasks",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .write          = rdtgroup_tasks_write,
                .seq_show       = rdtgroup_tasks_show,
                .fflags         = RFTYPE_BASE,
        },
        {
                .name           = "mon_hw_id",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdtgroup_rmid_show,
                .fflags         = RFTYPE_MON_BASE | RFTYPE_DEBUG,
        },
        {
                .name           = "schemata",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .write          = rdtgroup_schemata_write,
                .seq_show       = rdtgroup_schemata_show,
                .fflags         = RFTYPE_CTRL_BASE,
        },
        {
                .name           = "mba_MBps_event",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .write          = rdtgroup_mba_mbps_event_write,
                .seq_show       = rdtgroup_mba_mbps_event_show,
        },
        {
                .name           = "mode",
                .mode           = 0644,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .write          = rdtgroup_mode_write,
                .seq_show       = rdtgroup_mode_show,
                .fflags         = RFTYPE_CTRL_BASE,
        },
        {
                .name           = "size",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdtgroup_size_show,
                .fflags         = RFTYPE_CTRL_BASE,
        },
        {
                .name           = "sparse_masks",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdt_has_sparse_bitmasks_show,
                .fflags         = RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE,
        },
        {
                .name           = "ctrl_hw_id",
                .mode           = 0444,
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdtgroup_closid_show,
                .fflags         = RFTYPE_CTRL_BASE | RFTYPE_DEBUG,
        },
};

static int rdtgroup_add_files(struct kernfs_node *kn, unsigned long fflags)
{
        struct rftype *rfts, *rft;
        int ret, len;

        rfts = res_common_files;
        len = ARRAY_SIZE(res_common_files);

        lockdep_assert_held(&rdtgroup_mutex);

        if (resctrl_debug)
                fflags |= RFTYPE_DEBUG;

        for (rft = rfts; rft < rfts + len; rft++) {
                if (rft->fflags && ((fflags & rft->fflags) == rft->fflags)) {
                        ret = rdtgroup_add_file(kn, rft);
                        if (ret)
                                goto error;
                }
        }

        return 0;
error:
        pr_warn("Failed to add %s, err=%d\n", rft->name, ret);
        while (--rft >= rfts) {
                if ((fflags & rft->fflags) == rft->fflags)
                        kernfs_remove_by_name(kn, rft->name);
        }
        return ret;
}

static struct rftype *rdtgroup_get_rftype_by_name(const char *name)
{
        struct rftype *rfts, *rft;
        int len;

        rfts = res_common_files;
        len = ARRAY_SIZE(res_common_files);

        for (rft = rfts; rft < rfts + len; rft++) {
                if (!strcmp(rft->name, name))
                        return rft;
        }

        return NULL;
}

static void thread_throttle_mode_init(void)
{
        enum membw_throttle_mode throttle_mode = THREAD_THROTTLE_UNDEFINED;
        struct rdt_resource *r_mba, *r_smba;

        r_mba = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
        if (r_mba->alloc_capable &&
            r_mba->membw.throttle_mode != THREAD_THROTTLE_UNDEFINED)
                throttle_mode = r_mba->membw.throttle_mode;

        r_smba = resctrl_arch_get_resource(RDT_RESOURCE_SMBA);
        if (r_smba->alloc_capable &&
            r_smba->membw.throttle_mode != THREAD_THROTTLE_UNDEFINED)
                throttle_mode = r_smba->membw.throttle_mode;

        if (throttle_mode == THREAD_THROTTLE_UNDEFINED)
                return;

        resctrl_file_fflags_init("thread_throttle_mode",
                                 RFTYPE_CTRL_INFO | RFTYPE_RES_MB);
}

/*
 * The resctrl file "io_alloc" is added using L3 resource. However, it results
 * in this file being visible for *all* cache resources (eg. L2 cache),
 * whether it supports "io_alloc" or not.
 */
static void io_alloc_init(void)
{
        struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);

        if (r->cache.io_alloc_capable) {
                resctrl_file_fflags_init("io_alloc", RFTYPE_CTRL_INFO |
                                         RFTYPE_RES_CACHE);
                resctrl_file_fflags_init("io_alloc_cbm",
                                         RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE);
        }
}

void resctrl_file_fflags_init(const char *config, unsigned long fflags)
{
        struct rftype *rft;

        rft = rdtgroup_get_rftype_by_name(config);
        if (rft)
                rft->fflags = fflags;
}

/**
 * rdtgroup_kn_mode_restrict - Restrict user access to named resctrl file
 * @r: The resource group with which the file is associated.
 * @name: Name of the file
 *
 * The permissions of named resctrl file, directory, or link are modified
 * to not allow read, write, or execute by any user.
 *
 * WARNING: This function is intended to communicate to the user that the
 * resctrl file has been locked down - that it is not relevant to the
 * particular state the system finds itself in. It should not be relied
 * on to protect from user access because after the file's permissions
 * are restricted the user can still change the permissions using chmod
 * from the command line.
 *
 * Return: 0 on success, <0 on failure.
 */
int rdtgroup_kn_mode_restrict(struct rdtgroup *r, const char *name)
{
        struct iattr iattr = {.ia_valid = ATTR_MODE,};
        struct kernfs_node *kn;
        int ret = 0;

        kn = kernfs_find_and_get_ns(r->kn, name, NULL);
        if (!kn)
                return -ENOENT;

        switch (kernfs_type(kn)) {
        case KERNFS_DIR:
                iattr.ia_mode = S_IFDIR;
                break;
        case KERNFS_FILE:
                iattr.ia_mode = S_IFREG;
                break;
        case KERNFS_LINK:
                iattr.ia_mode = S_IFLNK;
                break;
        }

        ret = kernfs_setattr(kn, &iattr);
        kernfs_put(kn);
        return ret;
}

/**
 * rdtgroup_kn_mode_restore - Restore user access to named resctrl file
 * @r: The resource group with which the file is associated.
 * @name: Name of the file
 * @mask: Mask of permissions that should be restored
 *
 * Restore the permissions of the named file. If @name is a directory the
 * permissions of its parent will be used.
 *
 * Return: 0 on success, <0 on failure.
 */
int rdtgroup_kn_mode_restore(struct rdtgroup *r, const char *name,
                             umode_t mask)
{
        struct iattr iattr = {.ia_valid = ATTR_MODE,};
        struct kernfs_node *kn, *parent;
        struct rftype *rfts, *rft;
        int ret, len;

        rfts = res_common_files;
        len = ARRAY_SIZE(res_common_files);

        for (rft = rfts; rft < rfts + len; rft++) {
                if (!strcmp(rft->name, name))
                        iattr.ia_mode = rft->mode & mask;
        }

        kn = kernfs_find_and_get_ns(r->kn, name, NULL);
        if (!kn)
                return -ENOENT;

        switch (kernfs_type(kn)) {
        case KERNFS_DIR:
                parent = kernfs_get_parent(kn);
                if (parent) {
                        iattr.ia_mode |= parent->mode;
                        kernfs_put(parent);
                }
                iattr.ia_mode |= S_IFDIR;
                break;
        case KERNFS_FILE:
                iattr.ia_mode |= S_IFREG;
                break;
        case KERNFS_LINK:
                iattr.ia_mode |= S_IFLNK;
                break;
        }

        ret = kernfs_setattr(kn, &iattr);
        kernfs_put(kn);
        return ret;
}

static int resctrl_mkdir_event_configs(struct rdt_resource *r, struct kernfs_node *l3_mon_kn)
{
        struct kernfs_node *kn_subdir, *kn_subdir2;
        struct mon_evt *mevt;
        int ret;

        kn_subdir = kernfs_create_dir(l3_mon_kn, "event_configs", l3_mon_kn->mode, NULL);
        if (IS_ERR(kn_subdir))
                return PTR_ERR(kn_subdir);

        ret = rdtgroup_kn_set_ugid(kn_subdir);
        if (ret)
                return ret;

        for_each_mon_event(mevt) {
                if (mevt->rid != r->rid || !mevt->enabled || !resctrl_is_mbm_event(mevt->evtid))
                        continue;

                kn_subdir2 = kernfs_create_dir(kn_subdir, mevt->name, kn_subdir->mode, mevt);
                if (IS_ERR(kn_subdir2)) {
                        ret = PTR_ERR(kn_subdir2);
                        goto out;
                }

                ret = rdtgroup_kn_set_ugid(kn_subdir2);
                if (ret)
                        goto out;

                ret = rdtgroup_add_files(kn_subdir2, RFTYPE_ASSIGN_CONFIG);
                if (ret)
                        break;
        }

out:
        return ret;
}

static int rdtgroup_mkdir_info_resdir(void *priv, char *name,
                                      unsigned long fflags)
{
        struct kernfs_node *kn_subdir;
        struct rdt_resource *r;
        int ret;

        kn_subdir = kernfs_create_dir(kn_info, name,
                                      kn_info->mode, priv);
        if (IS_ERR(kn_subdir))
                return PTR_ERR(kn_subdir);

        ret = rdtgroup_kn_set_ugid(kn_subdir);
        if (ret)
                return ret;

        ret = rdtgroup_add_files(kn_subdir, fflags);
        if (ret)
                return ret;

        if ((fflags & RFTYPE_MON_INFO) == RFTYPE_MON_INFO) {
                r = priv;
                if (r->mon.mbm_cntr_assignable) {
                        ret = resctrl_mkdir_event_configs(r, kn_subdir);
                        if (ret)
                                return ret;
                        /*
                         * Hide BMEC related files if mbm_event mode
                         * is enabled.
                         */
                        if (resctrl_arch_mbm_cntr_assign_enabled(r))
                                resctrl_bmec_files_show(r, kn_subdir, false);
                }
        }

        kernfs_activate(kn_subdir);

        return ret;
}

static unsigned long fflags_from_resource(struct rdt_resource *r)
{
        switch (r->rid) {
        case RDT_RESOURCE_L3:
        case RDT_RESOURCE_L2:
                return RFTYPE_RES_CACHE;
        case RDT_RESOURCE_MBA:
        case RDT_RESOURCE_SMBA:
                return RFTYPE_RES_MB;
        case RDT_RESOURCE_PERF_PKG:
                return RFTYPE_RES_PERF_PKG;
        }

        return WARN_ON_ONCE(1);
}

static int rdtgroup_create_info_dir(struct kernfs_node *parent_kn)
{
        struct resctrl_schema *s;
        struct rdt_resource *r;
        unsigned long fflags;
        char name[32];
        int ret;

        /* create the directory */
        kn_info = kernfs_create_dir(parent_kn, "info", parent_kn->mode, NULL);
        if (IS_ERR(kn_info))
                return PTR_ERR(kn_info);

        ret = rdtgroup_add_files(kn_info, RFTYPE_TOP_INFO);
        if (ret)
                goto out_destroy;

        /* loop over enabled controls, these are all alloc_capable */
        list_for_each_entry(s, &resctrl_schema_all, list) {
                r = s->res;
                fflags = fflags_from_resource(r) | RFTYPE_CTRL_INFO;
                ret = rdtgroup_mkdir_info_resdir(s, s->name, fflags);
                if (ret)
                        goto out_destroy;
        }

        for_each_mon_capable_rdt_resource(r) {
                fflags = fflags_from_resource(r) | RFTYPE_MON_INFO;
                sprintf(name, "%s_MON", r->name);
                ret = rdtgroup_mkdir_info_resdir(r, name, fflags);
                if (ret)
                        goto out_destroy;
        }

        ret = rdtgroup_kn_set_ugid(kn_info);
        if (ret)
                goto out_destroy;

        kernfs_activate(kn_info);

        return 0;

out_destroy:
        kernfs_remove(kn_info);
        return ret;
}

static int
mongroup_create_dir(struct kernfs_node *parent_kn, struct rdtgroup *prgrp,
                    char *name, struct kernfs_node **dest_kn)
{
        struct kernfs_node *kn;
        int ret;

        /* create the directory */
        kn = kernfs_create_dir(parent_kn, name, parent_kn->mode, prgrp);
        if (IS_ERR(kn))
                return PTR_ERR(kn);

        if (dest_kn)
                *dest_kn = kn;

        ret = rdtgroup_kn_set_ugid(kn);
        if (ret)
                goto out_destroy;

        kernfs_activate(kn);

        return 0;

out_destroy:
        kernfs_remove(kn);
        return ret;
}

static inline bool is_mba_linear(void)
{
        return resctrl_arch_get_resource(RDT_RESOURCE_MBA)->membw.delay_linear;
}

static int mba_sc_domain_allocate(struct rdt_resource *r, struct rdt_ctrl_domain *d)
{
        u32 num_closid = resctrl_arch_get_num_closid(r);
        int cpu = cpumask_any(&d->hdr.cpu_mask);
        int i;

        d->mbps_val = kcalloc_node(num_closid, sizeof(*d->mbps_val),
                                   GFP_KERNEL, cpu_to_node(cpu));
        if (!d->mbps_val)
                return -ENOMEM;

        for (i = 0; i < num_closid; i++)
                d->mbps_val[i] = MBA_MAX_MBPS;

        return 0;
}

static void mba_sc_domain_destroy(struct rdt_resource *r,
                                  struct rdt_ctrl_domain *d)
{
        kfree(d->mbps_val);
        d->mbps_val = NULL;
}

/*
 * MBA software controller is supported only if
 * MBM is supported and MBA is in linear scale,
 * and the MBM monitor scope is the same as MBA
 * control scope.
 */
static bool supports_mba_mbps(void)
{
        struct rdt_resource *rmbm = resctrl_arch_get_resource(RDT_RESOURCE_L3);
        struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_MBA);

        return (resctrl_is_mbm_enabled() &&
                r->alloc_capable && is_mba_linear() &&
                r->ctrl_scope == rmbm->mon_scope);
}

/*
 * Enable or disable the MBA software controller
 * which helps user specify bandwidth in MBps.
 */
static int set_mba_sc(bool mba_sc)
{
        struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
        u32 num_closid = resctrl_arch_get_num_closid(r);
        struct rdt_ctrl_domain *d;
        unsigned long fflags;
        int i;

        if (!supports_mba_mbps() || mba_sc == is_mba_sc(r))
                return -EINVAL;

        r->membw.mba_sc = mba_sc;

        rdtgroup_default.mba_mbps_event = mba_mbps_default_event;

        list_for_each_entry(d, &r->ctrl_domains, hdr.list) {
                for (i = 0; i < num_closid; i++)
                        d->mbps_val[i] = MBA_MAX_MBPS;
        }

        fflags = mba_sc ? RFTYPE_CTRL_BASE | RFTYPE_MON_BASE : 0;
        resctrl_file_fflags_init("mba_MBps_event", fflags);

        return 0;
}

/*
 * We don't allow rdtgroup directories to be created anywhere
 * except the root directory. Thus when looking for the rdtgroup
 * structure for a kernfs node we are either looking at a directory,
 * in which case the rdtgroup structure is pointed at by the "priv"
 * field, otherwise we have a file, and need only look to the parent
 * to find the rdtgroup.
 */
static struct rdtgroup *kernfs_to_rdtgroup(struct kernfs_node *kn)
{
        if (kernfs_type(kn) == KERNFS_DIR) {
                /*
                 * All the resource directories use "kn->priv"
                 * to point to the "struct rdtgroup" for the
                 * resource. "info" and its subdirectories don't
                 * have rdtgroup structures, so return NULL here.
                 */
                if (kn == kn_info ||
                    rcu_access_pointer(kn->__parent) == kn_info)
                        return NULL;
                else
                        return kn->priv;
        } else {
                return rdt_kn_parent_priv(kn);
        }
}

static void rdtgroup_kn_get(struct rdtgroup *rdtgrp, struct kernfs_node *kn)
{
        atomic_inc(&rdtgrp->waitcount);
        kernfs_break_active_protection(kn);
}

static void rdtgroup_kn_put(struct rdtgroup *rdtgrp, struct kernfs_node *kn)
{
        if (atomic_dec_and_test(&rdtgrp->waitcount) &&
            (rdtgrp->flags & RDT_DELETED)) {
                if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
                    rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED)
                        rdtgroup_pseudo_lock_remove(rdtgrp);
                kernfs_unbreak_active_protection(kn);
                rdtgroup_remove(rdtgrp);
        } else {
                kernfs_unbreak_active_protection(kn);
        }
}

struct rdtgroup *rdtgroup_kn_lock_live(struct kernfs_node *kn)
{
        struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn);

        if (!rdtgrp)
                return NULL;

        rdtgroup_kn_get(rdtgrp, kn);

        cpus_read_lock();
        mutex_lock(&rdtgroup_mutex);

        /* Was this group deleted while we waited? */
        if (rdtgrp->flags & RDT_DELETED)
                return NULL;

        return rdtgrp;
}

void rdtgroup_kn_unlock(struct kernfs_node *kn)
{
        struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn);

        if (!rdtgrp)
                return;

        mutex_unlock(&rdtgroup_mutex);
        cpus_read_unlock();

        rdtgroup_kn_put(rdtgrp, kn);
}

static int mkdir_mondata_all(struct kernfs_node *parent_kn,
                             struct rdtgroup *prgrp,
                             struct kernfs_node **mon_data_kn);

static void rdt_disable_ctx(void)
{
        resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, false);
        resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, false);
        set_mba_sc(false);

        resctrl_debug = false;
}

static int rdt_enable_ctx(struct rdt_fs_context *ctx)
{
        int ret = 0;

        if (ctx->enable_cdpl2) {
                ret = resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, true);
                if (ret)
                        goto out_done;
        }

        if (ctx->enable_cdpl3) {
                ret = resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, true);
                if (ret)
                        goto out_cdpl2;
        }

        if (ctx->enable_mba_mbps) {
                ret = set_mba_sc(true);
                if (ret)
                        goto out_cdpl3;
        }

        if (ctx->enable_debug)
                resctrl_debug = true;

        return 0;

out_cdpl3:
        resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, false);
out_cdpl2:
        resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, false);
out_done:
        return ret;
}

static int schemata_list_add(struct rdt_resource *r, enum resctrl_conf_type type)
{
        struct resctrl_schema *s;
        const char *suffix = "";
        int ret, cl;

        s = kzalloc_obj(*s);
        if (!s)
                return -ENOMEM;

        s->res = r;
        s->num_closid = resctrl_arch_get_num_closid(r);
        if (resctrl_arch_get_cdp_enabled(r->rid))
                s->num_closid /= 2;

        s->conf_type = type;
        switch (type) {
        case CDP_CODE:
                suffix = "CODE";
                break;
        case CDP_DATA:
                suffix = "DATA";
                break;
        case CDP_NONE:
                suffix = "";
                break;
        }

        ret = snprintf(s->name, sizeof(s->name), "%s%s", r->name, suffix);
        if (ret >= sizeof(s->name)) {
                kfree(s);
                return -EINVAL;
        }

        cl = strlen(s->name);

        /*
         * If CDP is supported by this resource, but not enabled,
         * include the suffix. This ensures the tabular format of the
         * schemata file does not change between mounts of the filesystem.
         */
        if (r->cdp_capable && !resctrl_arch_get_cdp_enabled(r->rid))
                cl += 4;

        if (cl > max_name_width)
                max_name_width = cl;

        switch (r->schema_fmt) {
        case RESCTRL_SCHEMA_BITMAP:
                s->fmt_str = "%d=%x";
                break;
        case RESCTRL_SCHEMA_RANGE:
                s->fmt_str = "%d=%u";
                break;
        }

        if (WARN_ON_ONCE(!s->fmt_str)) {
                kfree(s);
                return -EINVAL;
        }

        INIT_LIST_HEAD(&s->list);
        list_add(&s->list, &resctrl_schema_all);

        return 0;
}

static int schemata_list_create(void)
{
        struct rdt_resource *r;
        int ret = 0;

        for_each_alloc_capable_rdt_resource(r) {
                if (resctrl_arch_get_cdp_enabled(r->rid)) {
                        ret = schemata_list_add(r, CDP_CODE);
                        if (ret)
                                break;

                        ret = schemata_list_add(r, CDP_DATA);
                } else {
                        ret = schemata_list_add(r, CDP_NONE);
                }

                if (ret)
                        break;
        }

        return ret;
}

static void schemata_list_destroy(void)
{
        struct resctrl_schema *s, *tmp;

        list_for_each_entry_safe(s, tmp, &resctrl_schema_all, list) {
                list_del(&s->list);
                kfree(s);
        }
}

static int rdt_get_tree(struct fs_context *fc)
{
        struct rdt_fs_context *ctx = rdt_fc2context(fc);
        unsigned long flags = RFTYPE_CTRL_BASE;
        struct rdt_l3_mon_domain *dom;
        struct rdt_resource *r;
        int ret;

        DO_ONCE_SLEEPABLE(resctrl_arch_pre_mount);

        cpus_read_lock();
        mutex_lock(&rdtgroup_mutex);
        /*
         * resctrl file system can only be mounted once.
         */
        if (resctrl_mounted) {
                ret = -EBUSY;
                goto out;
        }

        ret = setup_rmid_lru_list();
        if (ret)
                goto out;

        ret = rdtgroup_setup_root(ctx);
        if (ret)
                goto out;

        ret = rdt_enable_ctx(ctx);
        if (ret)
                goto out_root;

        ret = schemata_list_create();
        if (ret)
                goto out_schemata_free;

        ret = closid_init();
        if (ret)
                goto out_schemata_free;

        if (resctrl_arch_mon_capable())
                flags |= RFTYPE_MON;

        ret = rdtgroup_add_files(rdtgroup_default.kn, flags);
        if (ret)
                goto out_closid_exit;

        kernfs_activate(rdtgroup_default.kn);

        ret = rdtgroup_create_info_dir(rdtgroup_default.kn);
        if (ret < 0)
                goto out_closid_exit;

        if (resctrl_arch_mon_capable()) {
                ret = mongroup_create_dir(rdtgroup_default.kn,
                                          &rdtgroup_default, "mon_groups",
                                          &kn_mongrp);
                if (ret < 0)
                        goto out_info;

                rdtgroup_assign_cntrs(&rdtgroup_default);

                ret = mkdir_mondata_all(rdtgroup_default.kn,
                                        &rdtgroup_default, &kn_mondata);
                if (ret < 0)
                        goto out_mongrp;
                rdtgroup_default.mon.mon_data_kn = kn_mondata;
        }

        ret = rdt_pseudo_lock_init();
        if (ret)
                goto out_mondata;

        ret = kernfs_get_tree(fc);
        if (ret < 0)
                goto out_psl;

        if (resctrl_arch_alloc_capable())
                resctrl_arch_enable_alloc();
        if (resctrl_arch_mon_capable())
                resctrl_arch_enable_mon();

        if (resctrl_arch_alloc_capable() || resctrl_arch_mon_capable())
                resctrl_mounted = true;

        if (resctrl_is_mbm_enabled()) {
                r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
                list_for_each_entry(dom, &r->mon_domains, hdr.list)
                        mbm_setup_overflow_handler(dom, MBM_OVERFLOW_INTERVAL,
                                                   RESCTRL_PICK_ANY_CPU);
        }

        goto out;

out_psl:
        rdt_pseudo_lock_release();
out_mondata:
        if (resctrl_arch_mon_capable())
                kernfs_remove(kn_mondata);
out_mongrp:
        if (resctrl_arch_mon_capable()) {
                rdtgroup_unassign_cntrs(&rdtgroup_default);
                kernfs_remove(kn_mongrp);
        }
out_info:
        kernfs_remove(kn_info);
out_closid_exit:
        closid_exit();
out_schemata_free:
        schemata_list_destroy();
        rdt_disable_ctx();
out_root:
        rdtgroup_destroy_root();
out:
        rdt_last_cmd_clear();
        mutex_unlock(&rdtgroup_mutex);
        cpus_read_unlock();
        return ret;
}

enum rdt_param {
        Opt_cdp,
        Opt_cdpl2,
        Opt_mba_mbps,
        Opt_debug,
        nr__rdt_params
};

static const struct fs_parameter_spec rdt_fs_parameters[] = {
        fsparam_flag("cdp",             Opt_cdp),
        fsparam_flag("cdpl2",           Opt_cdpl2),
        fsparam_flag("mba_MBps",        Opt_mba_mbps),
        fsparam_flag("debug",           Opt_debug),
        {}
};

static int rdt_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
        struct rdt_fs_context *ctx = rdt_fc2context(fc);
        struct fs_parse_result result;
        const char *msg;
        int opt;

        opt = fs_parse(fc, rdt_fs_parameters, param, &result);
        if (opt < 0)
                return opt;

        switch (opt) {
        case Opt_cdp:
                ctx->enable_cdpl3 = true;
                return 0;
        case Opt_cdpl2:
                ctx->enable_cdpl2 = true;
                return 0;
        case Opt_mba_mbps:
                msg = "mba_MBps requires MBM and linear scale MBA at L3 scope";
                if (!supports_mba_mbps())
                        return invalfc(fc, msg);
                ctx->enable_mba_mbps = true;
                return 0;
        case Opt_debug:
                ctx->enable_debug = true;
                return 0;
        }

        return -EINVAL;
}

static void rdt_fs_context_free(struct fs_context *fc)
{
        struct rdt_fs_context *ctx = rdt_fc2context(fc);

        kernfs_free_fs_context(fc);
        kfree(ctx);
}

static const struct fs_context_operations rdt_fs_context_ops = {
        .free           = rdt_fs_context_free,
        .parse_param    = rdt_parse_param,
        .get_tree       = rdt_get_tree,
};

static int rdt_init_fs_context(struct fs_context *fc)
{
        struct rdt_fs_context *ctx;

        ctx = kzalloc_obj(*ctx);
        if (!ctx)
                return -ENOMEM;

        ctx->kfc.magic = RDTGROUP_SUPER_MAGIC;
        fc->fs_private = &ctx->kfc;
        fc->ops = &rdt_fs_context_ops;
        put_user_ns(fc->user_ns);
        fc->user_ns = get_user_ns(&init_user_ns);
        fc->global = true;
        return 0;
}

/*
 * Move tasks from one to the other group. If @from is NULL, then all tasks
 * in the systems are moved unconditionally (used for teardown).
 *
 * If @mask is not NULL the cpus on which moved tasks are running are set
 * in that mask so the update smp function call is restricted to affected
 * cpus.
 */
static void rdt_move_group_tasks(struct rdtgroup *from, struct rdtgroup *to,
                                 struct cpumask *mask)
{
        struct task_struct *p, *t;

        read_lock(&tasklist_lock);
        for_each_process_thread(p, t) {
                if (!from || is_closid_match(t, from) ||
                    is_rmid_match(t, from)) {
                        resctrl_arch_set_closid_rmid(t, to->closid,
                                                     to->mon.rmid);

                        /*
                         * Order the closid/rmid stores above before the loads
                         * in task_curr(). This pairs with the full barrier
                         * between the rq->curr update and
                         * resctrl_arch_sched_in() during context switch.
                         */
                        smp_mb();

                        /*
                         * If the task is on a CPU, set the CPU in the mask.
                         * The detection is inaccurate as tasks might move or
                         * schedule before the smp function call takes place.
                         * In such a case the function call is pointless, but
                         * there is no other side effect.
                         */
                        if (IS_ENABLED(CONFIG_SMP) && mask && task_curr(t))
                                cpumask_set_cpu(task_cpu(t), mask);
                }
        }
        read_unlock(&tasklist_lock);
}

static void free_all_child_rdtgrp(struct rdtgroup *rdtgrp)
{
        struct rdtgroup *sentry, *stmp;
        struct list_head *head;

        head = &rdtgrp->mon.crdtgrp_list;
        list_for_each_entry_safe(sentry, stmp, head, mon.crdtgrp_list) {
                rdtgroup_unassign_cntrs(sentry);
                free_rmid(sentry->closid, sentry->mon.rmid);
                list_del(&sentry->mon.crdtgrp_list);

                if (atomic_read(&sentry->waitcount) != 0)
                        sentry->flags = RDT_DELETED;
                else
                        rdtgroup_remove(sentry);
        }
}

/*
 * Forcibly remove all of subdirectories under root.
 */
static void rmdir_all_sub(void)
{
        struct rdtgroup *rdtgrp, *tmp;

        /* Move all tasks to the default resource group */
        rdt_move_group_tasks(NULL, &rdtgroup_default, NULL);

        list_for_each_entry_safe(rdtgrp, tmp, &rdt_all_groups, rdtgroup_list) {
                /* Free any child rmids */
                free_all_child_rdtgrp(rdtgrp);

                /* Remove each rdtgroup other than root */
                if (rdtgrp == &rdtgroup_default)
                        continue;

                if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
                    rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED)
                        rdtgroup_pseudo_lock_remove(rdtgrp);

                /*
                 * Give any CPUs back to the default group. We cannot copy
                 * cpu_online_mask because a CPU might have executed the
                 * offline callback already, but is still marked online.
                 */
                cpumask_or(&rdtgroup_default.cpu_mask,
                           &rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);

                rdtgroup_unassign_cntrs(rdtgrp);

                free_rmid(rdtgrp->closid, rdtgrp->mon.rmid);

                kernfs_remove(rdtgrp->kn);
                list_del(&rdtgrp->rdtgroup_list);

                if (atomic_read(&rdtgrp->waitcount) != 0)
                        rdtgrp->flags = RDT_DELETED;
                else
                        rdtgroup_remove(rdtgrp);
        }
        /* Notify online CPUs to update per cpu storage and PQR_ASSOC MSR */
        update_closid_rmid(cpu_online_mask, &rdtgroup_default);

        kernfs_remove(kn_info);
        kernfs_remove(kn_mongrp);
        kernfs_remove(kn_mondata);
}

/**
 * mon_get_kn_priv() - Get the mon_data priv data for this event.
 *
 * The same values are used across the mon_data directories of all control and
 * monitor groups for the same event in the same domain. Keep a list of
 * allocated structures and re-use an existing one with the same values for
 * @rid, @domid, etc.
 *
 * @rid:    The resource id for the event file being created.
 * @domid:  The domain id for the event file being created.
 * @mevt:   The type of event file being created.
 * @do_sum: Whether SNC summing monitors are being created. Only set
 *          when @rid == RDT_RESOURCE_L3.
 */
static struct mon_data *mon_get_kn_priv(enum resctrl_res_level rid, int domid,
                                        struct mon_evt *mevt,
                                        bool do_sum)
{
        struct mon_data *priv;

        lockdep_assert_held(&rdtgroup_mutex);

        list_for_each_entry(priv, &mon_data_kn_priv_list, list) {
                if (priv->rid == rid && priv->domid == domid &&
                    priv->sum == do_sum && priv->evt == mevt)
                        return priv;
        }

        priv = kzalloc_obj(*priv);
        if (!priv)
                return NULL;

        priv->rid = rid;
        priv->domid = domid;
        priv->sum = do_sum;
        priv->evt = mevt;
        list_add_tail(&priv->list, &mon_data_kn_priv_list);

        return priv;
}

/**
 * mon_put_kn_priv() - Free all allocated mon_data structures.
 *
 * Called when resctrl file system is unmounted.
 */
static void mon_put_kn_priv(void)
{
        struct mon_data *priv, *tmp;

        lockdep_assert_held(&rdtgroup_mutex);

        list_for_each_entry_safe(priv, tmp, &mon_data_kn_priv_list, list) {
                list_del(&priv->list);
                kfree(priv);
        }
}

static void resctrl_fs_teardown(void)
{
        lockdep_assert_held(&rdtgroup_mutex);

        /* Cleared by rdtgroup_destroy_root() */
        if (!rdtgroup_default.kn)
                return;

        rmdir_all_sub();
        rdtgroup_unassign_cntrs(&rdtgroup_default);
        mon_put_kn_priv();
        rdt_pseudo_lock_release();
        rdtgroup_default.mode = RDT_MODE_SHAREABLE;
        closid_exit();
        schemata_list_destroy();
        rdtgroup_destroy_root();
}

static void rdt_kill_sb(struct super_block *sb)
{
        struct rdt_resource *r;

        cpus_read_lock();
        mutex_lock(&rdtgroup_mutex);

        rdt_disable_ctx();

        /* Put everything back to default values. */
        for_each_alloc_capable_rdt_resource(r)
                resctrl_arch_reset_all_ctrls(r);

        resctrl_fs_teardown();
        if (resctrl_arch_alloc_capable())
                resctrl_arch_disable_alloc();
        if (resctrl_arch_mon_capable())
                resctrl_arch_disable_mon();
        resctrl_mounted = false;
        kernfs_kill_sb(sb);
        mutex_unlock(&rdtgroup_mutex);
        cpus_read_unlock();
}

static struct file_system_type rdt_fs_type = {
        .name                   = "resctrl",
        .init_fs_context        = rdt_init_fs_context,
        .parameters             = rdt_fs_parameters,
        .kill_sb                = rdt_kill_sb,
};

static int mon_addfile(struct kernfs_node *parent_kn, const char *name,
                       void *priv)
{
        struct kernfs_node *kn;
        int ret = 0;

        kn = __kernfs_create_file(parent_kn, name, 0444,
                                  GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, 0,
                                  &kf_mondata_ops, priv, NULL, NULL);
        if (IS_ERR(kn))
                return PTR_ERR(kn);

        ret = rdtgroup_kn_set_ugid(kn);
        if (ret) {
                kernfs_remove(kn);
                return ret;
        }

        return ret;
}

static void mon_rmdir_one_subdir(struct kernfs_node *pkn, char *name, char *subname)
{
        struct kernfs_node *kn;

        kn = kernfs_find_and_get(pkn, name);
        if (!kn)
                return;
        kernfs_put(kn);

        if (kn->dir.subdirs <= 1)
                kernfs_remove(kn);
        else
                kernfs_remove_by_name(kn, subname);
}

/*
 * Remove files and directories for one SNC node. If it is the last node
 * sharing an L3 cache, then remove the upper level directory containing
 * the "sum" files too.
 */
static void rmdir_mondata_subdir_allrdtgrp_snc(struct rdt_resource *r,
                                               struct rdt_domain_hdr *hdr)
{
        struct rdtgroup *prgrp, *crgrp;
        struct rdt_l3_mon_domain *d;
        char subname[32];
        char name[32];

        if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_L3))
                return;

        d = container_of(hdr, struct rdt_l3_mon_domain, hdr);
        sprintf(name, "mon_%s_%02d", r->name, d->ci_id);
        sprintf(subname, "mon_sub_%s_%02d", r->name, hdr->id);

        list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
                mon_rmdir_one_subdir(prgrp->mon.mon_data_kn, name, subname);

                list_for_each_entry(crgrp, &prgrp->mon.crdtgrp_list, mon.crdtgrp_list)
                        mon_rmdir_one_subdir(crgrp->mon.mon_data_kn, name, subname);
        }
}

/*
 * Remove all subdirectories of mon_data of ctrl_mon groups
 * and monitor groups for the given domain.
 */
static void rmdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
                                           struct rdt_domain_hdr *hdr)
{
        struct rdtgroup *prgrp, *crgrp;
        char name[32];

        if (r->rid == RDT_RESOURCE_L3 && r->mon_scope == RESCTRL_L3_NODE) {
                rmdir_mondata_subdir_allrdtgrp_snc(r, hdr);
                return;
        }

        sprintf(name, "mon_%s_%02d", r->name, hdr->id);
        list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
                kernfs_remove_by_name(prgrp->mon.mon_data_kn, name);

                list_for_each_entry(crgrp, &prgrp->mon.crdtgrp_list, mon.crdtgrp_list)
                        kernfs_remove_by_name(crgrp->mon.mon_data_kn, name);
        }
}

/*
 * Create a directory for a domain and populate it with monitor files. Create
 * summing monitors when @hdr is NULL. No need to initialize summing monitors.
 */
static struct kernfs_node *_mkdir_mondata_subdir(struct kernfs_node *parent_kn, char *name,
                                                 struct rdt_domain_hdr *hdr,
                                                 struct rdt_resource *r,
                                                 struct rdtgroup *prgrp, int domid)
{
        struct rmid_read rr = {0};
        struct kernfs_node *kn;
        struct mon_data *priv;
        struct mon_evt *mevt;
        int ret;

        kn = kernfs_create_dir(parent_kn, name, parent_kn->mode, prgrp);
        if (IS_ERR(kn))
                return kn;

        ret = rdtgroup_kn_set_ugid(kn);
        if (ret)
                goto out_destroy;

        for_each_mon_event(mevt) {
                if (mevt->rid != r->rid || !mevt->enabled)
                        continue;
                priv = mon_get_kn_priv(r->rid, domid, mevt, !hdr);
                if (WARN_ON_ONCE(!priv)) {
                        ret = -EINVAL;
                        goto out_destroy;
                }

                ret = mon_addfile(kn, mevt->name, priv);
                if (ret)
                        goto out_destroy;

                if (hdr && resctrl_is_mbm_event(mevt->evtid))
                        mon_event_read(&rr, r, hdr, prgrp, &hdr->cpu_mask, mevt, true);
        }

        return kn;
out_destroy:
        kernfs_remove(kn);
        return ERR_PTR(ret);
}

static int mkdir_mondata_subdir_snc(struct kernfs_node *parent_kn,
                                    struct rdt_domain_hdr *hdr,
                                    struct rdt_resource *r, struct rdtgroup *prgrp)
{
        struct kernfs_node *ckn, *kn;
        struct rdt_l3_mon_domain *d;
        char name[32];

        if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_L3))
                return -EINVAL;

        d = container_of(hdr, struct rdt_l3_mon_domain, hdr);
        sprintf(name, "mon_%s_%02d", r->name, d->ci_id);
        kn = kernfs_find_and_get(parent_kn, name);
        if (kn) {
                /*
                 * rdtgroup_mutex will prevent this directory from being
                 * removed. No need to keep this hold.
                 */
                kernfs_put(kn);
        } else {
                kn = _mkdir_mondata_subdir(parent_kn, name, NULL, r, prgrp, d->ci_id);
                if (IS_ERR(kn))
                        return PTR_ERR(kn);
        }

        sprintf(name, "mon_sub_%s_%02d", r->name, hdr->id);
        ckn = _mkdir_mondata_subdir(kn, name, hdr, r, prgrp, hdr->id);
        if (IS_ERR(ckn)) {
                kernfs_remove(kn);
                return PTR_ERR(ckn);
        }

        kernfs_activate(kn);
        return 0;
}

static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
                                struct rdt_domain_hdr *hdr,
                                struct rdt_resource *r, struct rdtgroup *prgrp)
{
        struct kernfs_node *kn;
        char name[32];

        lockdep_assert_held(&rdtgroup_mutex);

        if (r->rid == RDT_RESOURCE_L3 && r->mon_scope == RESCTRL_L3_NODE)
                return mkdir_mondata_subdir_snc(parent_kn, hdr, r, prgrp);

        sprintf(name, "mon_%s_%02d", r->name, hdr->id);
        kn = _mkdir_mondata_subdir(parent_kn, name, hdr, r, prgrp, hdr->id);
        if (IS_ERR(kn))
                return PTR_ERR(kn);

        kernfs_activate(kn);
        return 0;
}

/*
 * Add all subdirectories of mon_data for "ctrl_mon" groups
 * and "monitor" groups with given domain id.
 */
static void mkdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
                                           struct rdt_domain_hdr *hdr)
{
        struct kernfs_node *parent_kn;
        struct rdtgroup *prgrp, *crgrp;
        struct list_head *head;

        list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
                parent_kn = prgrp->mon.mon_data_kn;
                mkdir_mondata_subdir(parent_kn, hdr, r, prgrp);

                head = &prgrp->mon.crdtgrp_list;
                list_for_each_entry(crgrp, head, mon.crdtgrp_list) {
                        parent_kn = crgrp->mon.mon_data_kn;
                        mkdir_mondata_subdir(parent_kn, hdr, r, crgrp);
                }
        }
}

static int mkdir_mondata_subdir_alldom(struct kernfs_node *parent_kn,
                                       struct rdt_resource *r,
                                       struct rdtgroup *prgrp)
{
        struct rdt_domain_hdr *hdr;
        int ret;

        /* Walking r->domains, ensure it can't race with cpuhp */
        lockdep_assert_cpus_held();

        list_for_each_entry(hdr, &r->mon_domains, list) {
                ret = mkdir_mondata_subdir(parent_kn, hdr, r, prgrp);
                if (ret)
                        return ret;
        }

        return 0;
}

/*
 * This creates a directory mon_data which contains the monitored data.
 *
 * mon_data has one directory for each domain which are named
 * in the format mon_<domain_name>_<domain_id>. For ex: A mon_data
 * with L3 domain looks as below:
 * ./mon_data:
 * mon_L3_00
 * mon_L3_01
 * mon_L3_02
 * ...
 *
 * Each domain directory has one file per event:
 * ./mon_L3_00/:
 * llc_occupancy
 *
 */
static int mkdir_mondata_all(struct kernfs_node *parent_kn,
                             struct rdtgroup *prgrp,
                             struct kernfs_node **dest_kn)
{
        struct rdt_resource *r;
        struct kernfs_node *kn;
        int ret;

        /*
         * Create the mon_data directory first.
         */
        ret = mongroup_create_dir(parent_kn, prgrp, "mon_data", &kn);
        if (ret)
                return ret;

        if (dest_kn)
                *dest_kn = kn;

        /*
         * Create the subdirectories for each domain. Note that all events
         * in a domain like L3 are grouped into a resource whose domain is L3
         */
        for_each_mon_capable_rdt_resource(r) {
                ret = mkdir_mondata_subdir_alldom(kn, r, prgrp);
                if (ret)
                        goto out_destroy;
        }

        return 0;

out_destroy:
        kernfs_remove(kn);
        return ret;
}

/**
 * cbm_ensure_valid - Enforce validity on provided CBM
 * @_val:       Candidate CBM
 * @r:          RDT resource to which the CBM belongs
 *
 * The provided CBM represents all cache portions available for use. This
 * may be represented by a bitmap that does not consist of contiguous ones
 * and thus be an invalid CBM.
 * Here the provided CBM is forced to be a valid CBM by only considering
 * the first set of contiguous bits as valid and clearing all bits.
 * The intention here is to provide a valid default CBM with which a new
 * resource group is initialized. The user can follow this with a
 * modification to the CBM if the default does not satisfy the
 * requirements.
 */
static u32 cbm_ensure_valid(u32 _val, struct rdt_resource *r)
{
        unsigned int cbm_len = r->cache.cbm_len;
        unsigned long first_bit, zero_bit;
        unsigned long val;

        if (!_val || r->cache.arch_has_sparse_bitmasks)
                return _val;

        val = _val;
        first_bit = find_first_bit(&val, cbm_len);
        zero_bit = find_next_zero_bit(&val, cbm_len, first_bit);

        /* Clear any remaining bits to ensure contiguous region */
        bitmap_clear(&val, zero_bit, cbm_len - zero_bit);
        return (u32)val;
}

/*
 * Initialize cache resources per RDT domain
 *
 * Set the RDT domain up to start off with all usable allocations. That is,
 * all shareable and unused bits. All-zero CBM is invalid.
 */
static int __init_one_rdt_domain(struct rdt_ctrl_domain *d, struct resctrl_schema *s,
                                 u32 closid)
{
        enum resctrl_conf_type peer_type = resctrl_peer_type(s->conf_type);
        enum resctrl_conf_type t = s->conf_type;
        struct resctrl_staged_config *cfg;
        struct rdt_resource *r = s->res;
        u32 used_b = 0, unused_b = 0;
        unsigned long tmp_cbm;
        enum rdtgrp_mode mode;
        u32 peer_ctl, ctrl_val;
        int i;

        cfg = &d->staged_config[t];
        cfg->have_new_ctrl = false;
        cfg->new_ctrl = r->cache.shareable_bits;
        used_b = r->cache.shareable_bits;
        for (i = 0; i < closids_supported(); i++) {
                if (closid_allocated(i) && i != closid) {
                        mode = rdtgroup_mode_by_closid(i);
                        if (mode == RDT_MODE_PSEUDO_LOCKSETUP)
                                /*
                                 * ctrl values for locksetup aren't relevant
                                 * until the schemata is written, and the mode
                                 * becomes RDT_MODE_PSEUDO_LOCKED.
                                 */
                                continue;
                        /*
                         * If CDP is active include peer domain's
                         * usage to ensure there is no overlap
                         * with an exclusive group.
                         */
                        if (resctrl_arch_get_cdp_enabled(r->rid))
                                peer_ctl = resctrl_arch_get_config(r, d, i,
                                                                   peer_type);
                        else
                                peer_ctl = 0;
                        ctrl_val = resctrl_arch_get_config(r, d, i,
                                                           s->conf_type);
                        used_b |= ctrl_val | peer_ctl;
                        if (mode == RDT_MODE_SHAREABLE)
                                cfg->new_ctrl |= ctrl_val | peer_ctl;
                }
        }
        if (d->plr && d->plr->cbm > 0)
                used_b |= d->plr->cbm;
        unused_b = used_b ^ (BIT_MASK(r->cache.cbm_len) - 1);
        unused_b &= BIT_MASK(r->cache.cbm_len) - 1;
        cfg->new_ctrl |= unused_b;
        /*
         * Force the initial CBM to be valid, user can
         * modify the CBM based on system availability.
         */
        cfg->new_ctrl = cbm_ensure_valid(cfg->new_ctrl, r);
        /*
         * Assign the u32 CBM to an unsigned long to ensure that
         * bitmap_weight() does not access out-of-bound memory.
         */
        tmp_cbm = cfg->new_ctrl;
        if (bitmap_weight(&tmp_cbm, r->cache.cbm_len) < r->cache.min_cbm_bits) {
                rdt_last_cmd_printf("No space on %s:%d\n", s->name, d->hdr.id);
                return -ENOSPC;
        }
        cfg->have_new_ctrl = true;

        return 0;
}

/*
 * Initialize cache resources with default values.
 *
 * A new RDT group is being created on an allocation capable (CAT)
 * supporting system. Set this group up to start off with all usable
 * allocations.
 *
 * If there are no more shareable bits available on any domain then
 * the entire allocation will fail.
 */
int rdtgroup_init_cat(struct resctrl_schema *s, u32 closid)
{
        struct rdt_ctrl_domain *d;
        int ret;

        list_for_each_entry(d, &s->res->ctrl_domains, hdr.list) {
                ret = __init_one_rdt_domain(d, s, closid);
                if (ret < 0)
                        return ret;
        }

        return 0;
}

/* Initialize MBA resource with default values. */
static void rdtgroup_init_mba(struct rdt_resource *r, u32 closid)
{
        struct resctrl_staged_config *cfg;
        struct rdt_ctrl_domain *d;

        list_for_each_entry(d, &r->ctrl_domains, hdr.list) {
                if (is_mba_sc(r)) {
                        d->mbps_val[closid] = MBA_MAX_MBPS;
                        continue;
                }

                cfg = &d->staged_config[CDP_NONE];
                cfg->new_ctrl = resctrl_get_default_ctrl(r);
                cfg->have_new_ctrl = true;
        }
}

/* Initialize the RDT group's allocations. */
static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
{
        struct resctrl_schema *s;
        struct rdt_resource *r;
        int ret = 0;

        rdt_staged_configs_clear();

        list_for_each_entry(s, &resctrl_schema_all, list) {
                r = s->res;
                if (r->rid == RDT_RESOURCE_MBA ||
                    r->rid == RDT_RESOURCE_SMBA) {
                        rdtgroup_init_mba(r, rdtgrp->closid);
                        if (is_mba_sc(r))
                                continue;
                } else {
                        ret = rdtgroup_init_cat(s, rdtgrp->closid);
                        if (ret < 0)
                                goto out;
                }

                ret = resctrl_arch_update_domains(r, rdtgrp->closid);
                if (ret < 0) {
                        rdt_last_cmd_puts("Failed to initialize allocations\n");
                        goto out;
                }
        }

        rdtgrp->mode = RDT_MODE_SHAREABLE;

out:
        rdt_staged_configs_clear();
        return ret;
}

static int mkdir_rdt_prepare_rmid_alloc(struct rdtgroup *rdtgrp)
{
        int ret;

        if (!resctrl_arch_mon_capable())
                return 0;

        ret = alloc_rmid(rdtgrp->closid);
        if (ret < 0) {
                rdt_last_cmd_puts("Out of RMIDs\n");
                return ret;
        }
        rdtgrp->mon.rmid = ret;

        rdtgroup_assign_cntrs(rdtgrp);

        ret = mkdir_mondata_all(rdtgrp->kn, rdtgrp, &rdtgrp->mon.mon_data_kn);
        if (ret) {
                rdt_last_cmd_puts("kernfs subdir error\n");
                rdtgroup_unassign_cntrs(rdtgrp);
                free_rmid(rdtgrp->closid, rdtgrp->mon.rmid);
                return ret;
        }

        return 0;
}

static void mkdir_rdt_prepare_rmid_free(struct rdtgroup *rgrp)
{
        if (resctrl_arch_mon_capable()) {
                rdtgroup_unassign_cntrs(rgrp);
                free_rmid(rgrp->closid, rgrp->mon.rmid);
        }
}

/*
 * We allow creating mon groups only with in a directory called "mon_groups"
 * which is present in every ctrl_mon group. Check if this is a valid
 * "mon_groups" directory.
 *
 * 1. The directory should be named "mon_groups".
 * 2. The mon group itself should "not" be named "mon_groups".
 *   This makes sure "mon_groups" directory always has a ctrl_mon group
 *   as parent.
 */
static bool is_mon_groups(struct kernfs_node *kn, const char *name)
{
        return (!strcmp(rdt_kn_name(kn), "mon_groups") &&
                strcmp(name, "mon_groups"));
}

static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
                             const char *name, umode_t mode,
                             enum rdt_group_type rtype, struct rdtgroup **r)
{
        struct rdtgroup *prdtgrp, *rdtgrp;
        unsigned long files = 0;
        struct kernfs_node *kn;
        int ret;

        prdtgrp = rdtgroup_kn_lock_live(parent_kn);
        if (!prdtgrp) {
                ret = -ENODEV;
                goto out_unlock;
        }

        rdt_last_cmd_clear();

        /*
         * Check that the parent directory for a monitor group is a "mon_groups"
         * directory.
         */
        if (rtype == RDTMON_GROUP && !is_mon_groups(parent_kn, name)) {
                ret = -EPERM;
                goto out_unlock;
        }

        if (rtype == RDTMON_GROUP &&
            (prdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
             prdtgrp->mode == RDT_MODE_PSEUDO_LOCKED)) {
                ret = -EINVAL;
                rdt_last_cmd_puts("Pseudo-locking in progress\n");
                goto out_unlock;
        }

        /* allocate the rdtgroup. */
        rdtgrp = kzalloc_obj(*rdtgrp);
        if (!rdtgrp) {
                ret = -ENOSPC;
                rdt_last_cmd_puts("Kernel out of memory\n");
                goto out_unlock;
        }
        *r = rdtgrp;
        rdtgrp->mon.parent = prdtgrp;
        rdtgrp->type = rtype;
        INIT_LIST_HEAD(&rdtgrp->mon.crdtgrp_list);

        /* kernfs creates the directory for rdtgrp */
        kn = kernfs_create_dir(parent_kn, name, mode, rdtgrp);
        if (IS_ERR(kn)) {
                ret = PTR_ERR(kn);
                rdt_last_cmd_puts("kernfs create error\n");
                goto out_free_rgrp;
        }
        rdtgrp->kn = kn;

        /*
         * kernfs_remove() will drop the reference count on "kn" which
         * will free it. But we still need it to stick around for the
         * rdtgroup_kn_unlock(kn) call. Take one extra reference here,
         * which will be dropped by kernfs_put() in rdtgroup_remove().
         */
        kernfs_get(kn);

        ret = rdtgroup_kn_set_ugid(kn);
        if (ret) {
                rdt_last_cmd_puts("kernfs perm error\n");
                goto out_destroy;
        }

        if (rtype == RDTCTRL_GROUP) {
                files = RFTYPE_BASE | RFTYPE_CTRL;
                if (resctrl_arch_mon_capable())
                        files |= RFTYPE_MON;
        } else {
                files = RFTYPE_BASE | RFTYPE_MON;
        }

        ret = rdtgroup_add_files(kn, files);
        if (ret) {
                rdt_last_cmd_puts("kernfs fill error\n");
                goto out_destroy;
        }

        /*
         * The caller unlocks the parent_kn upon success.
         */
        return 0;

out_destroy:
        kernfs_put(rdtgrp->kn);
        kernfs_remove(rdtgrp->kn);
out_free_rgrp:
        kfree(rdtgrp);
out_unlock:
        rdtgroup_kn_unlock(parent_kn);
        return ret;
}

static void mkdir_rdt_prepare_clean(struct rdtgroup *rgrp)
{
        kernfs_remove(rgrp->kn);
        rdtgroup_remove(rgrp);
}

/*
 * Create a monitor group under "mon_groups" directory of a control
 * and monitor group(ctrl_mon). This is a resource group
 * to monitor a subset of tasks and cpus in its parent ctrl_mon group.
 */
static int rdtgroup_mkdir_mon(struct kernfs_node *parent_kn,
                              const char *name, umode_t mode)
{
        struct rdtgroup *rdtgrp, *prgrp;
        int ret;

        ret = mkdir_rdt_prepare(parent_kn, name, mode, RDTMON_GROUP, &rdtgrp);
        if (ret)
                return ret;

        prgrp = rdtgrp->mon.parent;
        rdtgrp->closid = prgrp->closid;

        ret = mkdir_rdt_prepare_rmid_alloc(rdtgrp);
        if (ret) {
                mkdir_rdt_prepare_clean(rdtgrp);
                goto out_unlock;
        }

        kernfs_activate(rdtgrp->kn);

        /*
         * Add the rdtgrp to the list of rdtgrps the parent
         * ctrl_mon group has to track.
         */
        list_add_tail(&rdtgrp->mon.crdtgrp_list, &prgrp->mon.crdtgrp_list);

out_unlock:
        rdtgroup_kn_unlock(parent_kn);
        return ret;
}

/*
 * These are rdtgroups created under the root directory. Can be used
 * to allocate and monitor resources.
 */
static int rdtgroup_mkdir_ctrl_mon(struct kernfs_node *parent_kn,
                                   const char *name, umode_t mode)
{
        struct rdtgroup *rdtgrp;
        struct kernfs_node *kn;
        u32 closid;
        int ret;

        ret = mkdir_rdt_prepare(parent_kn, name, mode, RDTCTRL_GROUP, &rdtgrp);
        if (ret)
                return ret;

        kn = rdtgrp->kn;
        ret = closid_alloc();
        if (ret < 0) {
                rdt_last_cmd_puts("Out of CLOSIDs\n");
                goto out_common_fail;
        }
        closid = ret;
        ret = 0;

        rdtgrp->closid = closid;

        ret = mkdir_rdt_prepare_rmid_alloc(rdtgrp);
        if (ret)
                goto out_closid_free;

        kernfs_activate(rdtgrp->kn);

        ret = rdtgroup_init_alloc(rdtgrp);
        if (ret < 0)
                goto out_rmid_free;

        list_add(&rdtgrp->rdtgroup_list, &rdt_all_groups);

        if (resctrl_arch_mon_capable()) {
                /*
                 * Create an empty mon_groups directory to hold the subset
                 * of tasks and cpus to monitor.
                 */
                ret = mongroup_create_dir(kn, rdtgrp, "mon_groups", NULL);
                if (ret) {
                        rdt_last_cmd_puts("kernfs subdir error\n");
                        goto out_del_list;
                }
                if (is_mba_sc(NULL))
                        rdtgrp->mba_mbps_event = mba_mbps_default_event;
        }

        goto out_unlock;

out_del_list:
        list_del(&rdtgrp->rdtgroup_list);
out_rmid_free:
        mkdir_rdt_prepare_rmid_free(rdtgrp);
out_closid_free:
        closid_free(closid);
out_common_fail:
        mkdir_rdt_prepare_clean(rdtgrp);
out_unlock:
        rdtgroup_kn_unlock(parent_kn);
        return ret;
}

static int rdtgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
                          umode_t mode)
{
        /* Do not accept '\n' to avoid unparsable situation. */
        if (strchr(name, '\n'))
                return -EINVAL;

        /*
         * If the parent directory is the root directory and RDT
         * allocation is supported, add a control and monitoring
         * subdirectory
         */
        if (resctrl_arch_alloc_capable() && parent_kn == rdtgroup_default.kn)
                return rdtgroup_mkdir_ctrl_mon(parent_kn, name, mode);

        /* Else, attempt to add a monitoring subdirectory. */
        if (resctrl_arch_mon_capable())
                return rdtgroup_mkdir_mon(parent_kn, name, mode);

        return -EPERM;
}

static int rdtgroup_rmdir_mon(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
{
        struct rdtgroup *prdtgrp = rdtgrp->mon.parent;
        u32 closid, rmid;
        int cpu;

        /* Give any tasks back to the parent group */
        rdt_move_group_tasks(rdtgrp, prdtgrp, tmpmask);

        /*
         * Update per cpu closid/rmid of the moved CPUs first.
         * Note: the closid will not change, but the arch code still needs it.
         */
        closid = prdtgrp->closid;
        rmid = prdtgrp->mon.rmid;
        for_each_cpu(cpu, &rdtgrp->cpu_mask)
                resctrl_arch_set_cpu_default_closid_rmid(cpu, closid, rmid);

        /*
         * Update the MSR on moved CPUs and CPUs which have moved
         * task running on them.
         */
        cpumask_or(tmpmask, tmpmask, &rdtgrp->cpu_mask);
        update_closid_rmid(tmpmask, NULL);

        rdtgrp->flags = RDT_DELETED;

        rdtgroup_unassign_cntrs(rdtgrp);

        free_rmid(rdtgrp->closid, rdtgrp->mon.rmid);

        /*
         * Remove the rdtgrp from the parent ctrl_mon group's list
         */
        WARN_ON(list_empty(&prdtgrp->mon.crdtgrp_list));
        list_del(&rdtgrp->mon.crdtgrp_list);

        kernfs_remove(rdtgrp->kn);

        return 0;
}

static int rdtgroup_ctrl_remove(struct rdtgroup *rdtgrp)
{
        rdtgrp->flags = RDT_DELETED;
        list_del(&rdtgrp->rdtgroup_list);

        kernfs_remove(rdtgrp->kn);
        return 0;
}

static int rdtgroup_rmdir_ctrl(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
{
        u32 closid, rmid;
        int cpu;

        /* Give any tasks back to the default group */
        rdt_move_group_tasks(rdtgrp, &rdtgroup_default, tmpmask);

        /* Give any CPUs back to the default group */
        cpumask_or(&rdtgroup_default.cpu_mask,
                   &rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);

        /* Update per cpu closid and rmid of the moved CPUs first */
        closid = rdtgroup_default.closid;
        rmid = rdtgroup_default.mon.rmid;
        for_each_cpu(cpu, &rdtgrp->cpu_mask)
                resctrl_arch_set_cpu_default_closid_rmid(cpu, closid, rmid);

        /*
         * Update the MSR on moved CPUs and CPUs which have moved
         * task running on them.
         */
        cpumask_or(tmpmask, tmpmask, &rdtgrp->cpu_mask);
        update_closid_rmid(tmpmask, NULL);

        rdtgroup_unassign_cntrs(rdtgrp);

        free_rmid(rdtgrp->closid, rdtgrp->mon.rmid);
        closid_free(rdtgrp->closid);

        rdtgroup_ctrl_remove(rdtgrp);

        /*
         * Free all the child monitor group rmids.
         */
        free_all_child_rdtgrp(rdtgrp);

        return 0;
}

static struct kernfs_node *rdt_kn_parent(struct kernfs_node *kn)
{
        /*
         * Valid within the RCU section it was obtained or while rdtgroup_mutex
         * is held.
         */
        return rcu_dereference_check(kn->__parent, lockdep_is_held(&rdtgroup_mutex));
}

static int rdtgroup_rmdir(struct kernfs_node *kn)
{
        struct kernfs_node *parent_kn;
        struct rdtgroup *rdtgrp;
        cpumask_var_t tmpmask;
        int ret = 0;

        if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL))
                return -ENOMEM;

        rdtgrp = rdtgroup_kn_lock_live(kn);
        if (!rdtgrp) {
                ret = -EPERM;
                goto out;
        }
        parent_kn = rdt_kn_parent(kn);

        /*
         * If the rdtgroup is a ctrl_mon group and parent directory
         * is the root directory, remove the ctrl_mon group.
         *
         * If the rdtgroup is a mon group and parent directory
         * is a valid "mon_groups" directory, remove the mon group.
         */
        if (rdtgrp->type == RDTCTRL_GROUP && parent_kn == rdtgroup_default.kn &&
            rdtgrp != &rdtgroup_default) {
                if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
                    rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
                        ret = rdtgroup_ctrl_remove(rdtgrp);
                } else {
                        ret = rdtgroup_rmdir_ctrl(rdtgrp, tmpmask);
                }
        } else if (rdtgrp->type == RDTMON_GROUP &&
                 is_mon_groups(parent_kn, rdt_kn_name(kn))) {
                ret = rdtgroup_rmdir_mon(rdtgrp, tmpmask);
        } else {
                ret = -EPERM;
        }

out:
        rdtgroup_kn_unlock(kn);
        free_cpumask_var(tmpmask);
        return ret;
}

/**
 * mongrp_reparent() - replace parent CTRL_MON group of a MON group
 * @rdtgrp:             the MON group whose parent should be replaced
 * @new_prdtgrp:        replacement parent CTRL_MON group for @rdtgrp
 * @cpus:               cpumask provided by the caller for use during this call
 *
 * Replaces the parent CTRL_MON group for a MON group, resulting in all member
 * tasks' CLOSID immediately changing to that of the new parent group.
 * Monitoring data for the group is unaffected by this operation.
 */
static void mongrp_reparent(struct rdtgroup *rdtgrp,
                            struct rdtgroup *new_prdtgrp,
                            cpumask_var_t cpus)
{
        struct rdtgroup *prdtgrp = rdtgrp->mon.parent;

        WARN_ON(rdtgrp->type != RDTMON_GROUP);
        WARN_ON(new_prdtgrp->type != RDTCTRL_GROUP);

        /* Nothing to do when simply renaming a MON group. */
        if (prdtgrp == new_prdtgrp)
                return;

        WARN_ON(list_empty(&prdtgrp->mon.crdtgrp_list));
        list_move_tail(&rdtgrp->mon.crdtgrp_list,
                       &new_prdtgrp->mon.crdtgrp_list);

        rdtgrp->mon.parent = new_prdtgrp;
        rdtgrp->closid = new_prdtgrp->closid;

        /* Propagate updated closid to all tasks in this group. */
        rdt_move_group_tasks(rdtgrp, rdtgrp, cpus);

        update_closid_rmid(cpus, NULL);
}

static int rdtgroup_rename(struct kernfs_node *kn,
                           struct kernfs_node *new_parent, const char *new_name)
{
        struct kernfs_node *kn_parent;
        struct rdtgroup *new_prdtgrp;
        struct rdtgroup *rdtgrp;
        cpumask_var_t tmpmask;
        int ret;

        rdtgrp = kernfs_to_rdtgroup(kn);
        new_prdtgrp = kernfs_to_rdtgroup(new_parent);
        if (!rdtgrp || !new_prdtgrp)
                return -ENOENT;

        /* Release both kernfs active_refs before obtaining rdtgroup mutex. */
        rdtgroup_kn_get(rdtgrp, kn);
        rdtgroup_kn_get(new_prdtgrp, new_parent);

        mutex_lock(&rdtgroup_mutex);

        rdt_last_cmd_clear();

        /*
         * Don't allow kernfs_to_rdtgroup() to return a parent rdtgroup if
         * either kernfs_node is a file.
         */
        if (kernfs_type(kn) != KERNFS_DIR ||
            kernfs_type(new_parent) != KERNFS_DIR) {
                rdt_last_cmd_puts("Source and destination must be directories");
                ret = -EPERM;
                goto out;
        }

        if ((rdtgrp->flags & RDT_DELETED) || (new_prdtgrp->flags & RDT_DELETED)) {
                ret = -ENOENT;
                goto out;
        }

        kn_parent = rdt_kn_parent(kn);
        if (rdtgrp->type != RDTMON_GROUP || !kn_parent ||
            !is_mon_groups(kn_parent, rdt_kn_name(kn))) {
                rdt_last_cmd_puts("Source must be a MON group\n");
                ret = -EPERM;
                goto out;
        }

        if (!is_mon_groups(new_parent, new_name)) {
                rdt_last_cmd_puts("Destination must be a mon_groups subdirectory\n");
                ret = -EPERM;
                goto out;
        }

        /*
         * If the MON group is monitoring CPUs, the CPUs must be assigned to the
         * current parent CTRL_MON group and therefore cannot be assigned to
         * the new parent, making the move illegal.
         */
        if (!cpumask_empty(&rdtgrp->cpu_mask) &&
            rdtgrp->mon.parent != new_prdtgrp) {
                rdt_last_cmd_puts("Cannot move a MON group that monitors CPUs\n");
                ret = -EPERM;
                goto out;
        }

        /*
         * Allocate the cpumask for use in mongrp_reparent() to avoid the
         * possibility of failing to allocate it after kernfs_rename() has
         * succeeded.
         */
        if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL)) {
                ret = -ENOMEM;
                goto out;
        }

        /*
         * Perform all input validation and allocations needed to ensure
         * mongrp_reparent() will succeed before calling kernfs_rename(),
         * otherwise it would be necessary to revert this call if
         * mongrp_reparent() failed.
         */
        ret = kernfs_rename(kn, new_parent, new_name);
        if (!ret)
                mongrp_reparent(rdtgrp, new_prdtgrp, tmpmask);

        free_cpumask_var(tmpmask);

out:
        mutex_unlock(&rdtgroup_mutex);
        rdtgroup_kn_put(rdtgrp, kn);
        rdtgroup_kn_put(new_prdtgrp, new_parent);
        return ret;
}

static int rdtgroup_show_options(struct seq_file *seq, struct kernfs_root *kf)
{
        if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L3))
                seq_puts(seq, ",cdp");

        if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L2))
                seq_puts(seq, ",cdpl2");

        if (is_mba_sc(resctrl_arch_get_resource(RDT_RESOURCE_MBA)))
                seq_puts(seq, ",mba_MBps");

        if (resctrl_debug)
                seq_puts(seq, ",debug");

        return 0;
}

static struct kernfs_syscall_ops rdtgroup_kf_syscall_ops = {
        .mkdir          = rdtgroup_mkdir,
        .rmdir          = rdtgroup_rmdir,
        .rename         = rdtgroup_rename,
        .show_options   = rdtgroup_show_options,
};

static int rdtgroup_setup_root(struct rdt_fs_context *ctx)
{
        rdt_root = kernfs_create_root(&rdtgroup_kf_syscall_ops,
                                      KERNFS_ROOT_CREATE_DEACTIVATED |
                                      KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK,
                                      &rdtgroup_default);
        if (IS_ERR(rdt_root))
                return PTR_ERR(rdt_root);

        ctx->kfc.root = rdt_root;
        rdtgroup_default.kn = kernfs_root_to_node(rdt_root);

        return 0;
}

static void rdtgroup_destroy_root(void)
{
        lockdep_assert_held(&rdtgroup_mutex);

        kernfs_destroy_root(rdt_root);
        rdtgroup_default.kn = NULL;
}

static void rdtgroup_setup_default(void)
{
        mutex_lock(&rdtgroup_mutex);

        rdtgroup_default.closid = RESCTRL_RESERVED_CLOSID;
        rdtgroup_default.mon.rmid = RESCTRL_RESERVED_RMID;
        rdtgroup_default.type = RDTCTRL_GROUP;
        INIT_LIST_HEAD(&rdtgroup_default.mon.crdtgrp_list);

        list_add(&rdtgroup_default.rdtgroup_list, &rdt_all_groups);

        mutex_unlock(&rdtgroup_mutex);
}

static void domain_destroy_l3_mon_state(struct rdt_l3_mon_domain *d)
{
        int idx;

        kfree(d->cntr_cfg);
        bitmap_free(d->rmid_busy_llc);
        for_each_mbm_idx(idx) {
                kfree(d->mbm_states[idx]);
                d->mbm_states[idx] = NULL;
        }
}

void resctrl_offline_ctrl_domain(struct rdt_resource *r, struct rdt_ctrl_domain *d)
{
        mutex_lock(&rdtgroup_mutex);

        if (supports_mba_mbps() && r->rid == RDT_RESOURCE_MBA)
                mba_sc_domain_destroy(r, d);

        mutex_unlock(&rdtgroup_mutex);
}

void resctrl_offline_mon_domain(struct rdt_resource *r, struct rdt_domain_hdr *hdr)
{
        struct rdt_l3_mon_domain *d;

        mutex_lock(&rdtgroup_mutex);

        /*
         * If resctrl is mounted, remove all the
         * per domain monitor data directories.
         */
        if (resctrl_mounted && resctrl_arch_mon_capable())
                rmdir_mondata_subdir_allrdtgrp(r, hdr);

        if (r->rid != RDT_RESOURCE_L3)
                goto out_unlock;

        if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_L3))
                goto out_unlock;

        d = container_of(hdr, struct rdt_l3_mon_domain, hdr);
        if (resctrl_is_mbm_enabled())
                cancel_delayed_work(&d->mbm_over);
        if (resctrl_is_mon_event_enabled(QOS_L3_OCCUP_EVENT_ID) && has_busy_rmid(d)) {
                /*
                 * When a package is going down, forcefully
                 * decrement rmid->ebusy. There is no way to know
                 * that the L3 was flushed and hence may lead to
                 * incorrect counts in rare scenarios, but leaving
                 * the RMID as busy creates RMID leaks if the
                 * package never comes back.
                 */
                __check_limbo(d, true);
                cancel_delayed_work(&d->cqm_limbo);
        }

        domain_destroy_l3_mon_state(d);
out_unlock:
        mutex_unlock(&rdtgroup_mutex);
}

/**
 * domain_setup_l3_mon_state() -  Initialise domain monitoring structures.
 * @r:  The resource for the newly online domain.
 * @d:  The newly online domain.
 *
 * Allocate monitor resources that belong to this domain.
 * Called when the first CPU of a domain comes online, regardless of whether
 * the filesystem is mounted.
 * During boot this may be called before global allocations have been made by
 * resctrl_l3_mon_resource_init().
 *
 * Called during CPU online that may run as soon as CPU online callbacks
 * are set up during resctrl initialization. The number of supported RMIDs
 * may be reduced if additional mon_capable resources are enumerated
 * at mount time. This means the rdt_l3_mon_domain::mbm_states[] and
 * rdt_l3_mon_domain::rmid_busy_llc allocations may be larger than needed.
 *
 * Return: 0 for success, or -ENOMEM.
 */
static int domain_setup_l3_mon_state(struct rdt_resource *r, struct rdt_l3_mon_domain *d)
{
        u32 idx_limit = resctrl_arch_system_num_rmid_idx();
        size_t tsize = sizeof(*d->mbm_states[0]);
        enum resctrl_event_id eventid;
        int idx;

        if (resctrl_is_mon_event_enabled(QOS_L3_OCCUP_EVENT_ID)) {
                d->rmid_busy_llc = bitmap_zalloc(idx_limit, GFP_KERNEL);
                if (!d->rmid_busy_llc)
                        return -ENOMEM;
        }

        for_each_mbm_event_id(eventid) {
                if (!resctrl_is_mon_event_enabled(eventid))
                        continue;
                idx = MBM_STATE_IDX(eventid);
                d->mbm_states[idx] = kcalloc(idx_limit, tsize, GFP_KERNEL);
                if (!d->mbm_states[idx])
                        goto cleanup;
        }

        if (resctrl_is_mbm_enabled() && r->mon.mbm_cntr_assignable) {
                tsize = sizeof(*d->cntr_cfg);
                d->cntr_cfg = kcalloc(r->mon.num_mbm_cntrs, tsize, GFP_KERNEL);
                if (!d->cntr_cfg)
                        goto cleanup;
        }

        return 0;
cleanup:
        bitmap_free(d->rmid_busy_llc);
        for_each_mbm_idx(idx) {
                kfree(d->mbm_states[idx]);
                d->mbm_states[idx] = NULL;
        }

        return -ENOMEM;
}

int resctrl_online_ctrl_domain(struct rdt_resource *r, struct rdt_ctrl_domain *d)
{
        int err = 0;

        mutex_lock(&rdtgroup_mutex);

        if (supports_mba_mbps() && r->rid == RDT_RESOURCE_MBA) {
                /* RDT_RESOURCE_MBA is never mon_capable */
                err = mba_sc_domain_allocate(r, d);
        }

        mutex_unlock(&rdtgroup_mutex);

        return err;
}

int resctrl_online_mon_domain(struct rdt_resource *r, struct rdt_domain_hdr *hdr)
{
        struct rdt_l3_mon_domain *d;
        int err = -EINVAL;

        mutex_lock(&rdtgroup_mutex);

        if (r->rid != RDT_RESOURCE_L3)
                goto mkdir;

        if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_L3))
                goto out_unlock;

        d = container_of(hdr, struct rdt_l3_mon_domain, hdr);
        err = domain_setup_l3_mon_state(r, d);
        if (err)
                goto out_unlock;

        if (resctrl_is_mbm_enabled()) {
                INIT_DELAYED_WORK(&d->mbm_over, mbm_handle_overflow);
                mbm_setup_overflow_handler(d, MBM_OVERFLOW_INTERVAL,
                                           RESCTRL_PICK_ANY_CPU);
        }

        if (resctrl_is_mon_event_enabled(QOS_L3_OCCUP_EVENT_ID))
                INIT_DELAYED_WORK(&d->cqm_limbo, cqm_handle_limbo);

mkdir:
        err = 0;
        /*
         * If the filesystem is not mounted then only the default resource group
         * exists. Creation of its directories is deferred until mount time
         * by rdt_get_tree() calling mkdir_mondata_all().
         * If resctrl is mounted, add per domain monitor data directories.
         */
        if (resctrl_mounted && resctrl_arch_mon_capable())
                mkdir_mondata_subdir_allrdtgrp(r, hdr);

out_unlock:
        mutex_unlock(&rdtgroup_mutex);

        return err;
}

void resctrl_online_cpu(unsigned int cpu)
{
        mutex_lock(&rdtgroup_mutex);
        /* The CPU is set in default rdtgroup after online. */
        cpumask_set_cpu(cpu, &rdtgroup_default.cpu_mask);
        mutex_unlock(&rdtgroup_mutex);
}

static void clear_childcpus(struct rdtgroup *r, unsigned int cpu)
{
        struct rdtgroup *cr;

        list_for_each_entry(cr, &r->mon.crdtgrp_list, mon.crdtgrp_list) {
                if (cpumask_test_and_clear_cpu(cpu, &cr->cpu_mask))
                        break;
        }
}

static struct rdt_l3_mon_domain *get_mon_domain_from_cpu(int cpu,
                                                         struct rdt_resource *r)
{
        struct rdt_l3_mon_domain *d;

        lockdep_assert_cpus_held();

        list_for_each_entry(d, &r->mon_domains, hdr.list) {
                /* Find the domain that contains this CPU */
                if (cpumask_test_cpu(cpu, &d->hdr.cpu_mask))
                        return d;
        }

        return NULL;
}

void resctrl_offline_cpu(unsigned int cpu)
{
        struct rdt_resource *l3 = resctrl_arch_get_resource(RDT_RESOURCE_L3);
        struct rdt_l3_mon_domain *d;
        struct rdtgroup *rdtgrp;

        mutex_lock(&rdtgroup_mutex);
        list_for_each_entry(rdtgrp, &rdt_all_groups, rdtgroup_list) {
                if (cpumask_test_and_clear_cpu(cpu, &rdtgrp->cpu_mask)) {
                        clear_childcpus(rdtgrp, cpu);
                        break;
                }
        }

        if (!l3->mon_capable)
                goto out_unlock;

        d = get_mon_domain_from_cpu(cpu, l3);
        if (d) {
                if (resctrl_is_mbm_enabled() && cpu == d->mbm_work_cpu) {
                        cancel_delayed_work(&d->mbm_over);
                        mbm_setup_overflow_handler(d, 0, cpu);
                }
                if (resctrl_is_mon_event_enabled(QOS_L3_OCCUP_EVENT_ID) &&
                    cpu == d->cqm_work_cpu && has_busy_rmid(d)) {
                        cancel_delayed_work(&d->cqm_limbo);
                        cqm_setup_limbo_handler(d, 0, cpu);
                }
        }

out_unlock:
        mutex_unlock(&rdtgroup_mutex);
}

/*
 * resctrl_init - resctrl filesystem initialization
 *
 * Setup resctrl file system including set up root, create mount point,
 * register resctrl filesystem, and initialize files under root directory.
 *
 * Return: 0 on success or -errno
 */
int resctrl_init(void)
{
        int ret = 0;

        seq_buf_init(&last_cmd_status, last_cmd_status_buf,
                     sizeof(last_cmd_status_buf));

        rdtgroup_setup_default();

        thread_throttle_mode_init();

        io_alloc_init();

        ret = resctrl_l3_mon_resource_init();
        if (ret)
                return ret;

        ret = sysfs_create_mount_point(fs_kobj, "resctrl");
        if (ret) {
                resctrl_l3_mon_resource_exit();
                return ret;
        }

        ret = register_filesystem(&rdt_fs_type);
        if (ret)
                goto cleanup_mountpoint;

        /*
         * Adding the resctrl debugfs directory here may not be ideal since
         * it would let the resctrl debugfs directory appear on the debugfs
         * filesystem before the resctrl filesystem is mounted.
         * It may also be ok since that would enable debugging of RDT before
         * resctrl is mounted.
         * The reason why the debugfs directory is created here and not in
         * rdt_get_tree() is because rdt_get_tree() takes rdtgroup_mutex and
         * during the debugfs directory creation also &sb->s_type->i_mutex_key
         * (the lockdep class of inode->i_rwsem). Other filesystem
         * interactions (eg. SyS_getdents) have the lock ordering:
         * &sb->s_type->i_mutex_key --> &mm->mmap_lock
         * During mmap(), called with &mm->mmap_lock, the rdtgroup_mutex
         * is taken, thus creating dependency:
         * &mm->mmap_lock --> rdtgroup_mutex for the latter that can cause
         * issues considering the other two lock dependencies.
         * By creating the debugfs directory here we avoid a dependency
         * that may cause deadlock (even though file operations cannot
         * occur until the filesystem is mounted, but I do not know how to
         * tell lockdep that).
         */
        debugfs_resctrl = debugfs_create_dir("resctrl", NULL);

        return 0;

cleanup_mountpoint:
        sysfs_remove_mount_point(fs_kobj, "resctrl");
        resctrl_l3_mon_resource_exit();

        return ret;
}

static bool resctrl_online_domains_exist(void)
{
        struct rdt_resource *r;

        /*
         * Only walk capable resources to allow resctrl_arch_get_resource()
         * to return dummy 'not capable' resources.
         */
        for_each_alloc_capable_rdt_resource(r) {
                if (!list_empty(&r->ctrl_domains))
                        return true;
        }

        for_each_mon_capable_rdt_resource(r) {
                if (!list_empty(&r->mon_domains))
                        return true;
        }

        return false;
}

/**
 * resctrl_exit() - Remove the resctrl filesystem and free resources.
 *
 * Called by the architecture code in response to a fatal error.
 * Removes resctrl files and structures from kernfs to prevent further
 * configuration.
 *
 * When called by the architecture code, all CPUs and resctrl domains must be
 * offline. This ensures the limbo and overflow handlers are not scheduled to
 * run, meaning the data structures they access can be freed by
 * resctrl_l3_mon_resource_exit().
 *
 * After resctrl_exit() returns, the architecture code should return an
 * error from all resctrl_arch_ functions that can do this.
 * resctrl_arch_get_resource() must continue to return struct rdt_resources
 * with the correct rid field to ensure the filesystem can be unmounted.
 */
void resctrl_exit(void)
{
        cpus_read_lock();
        WARN_ON_ONCE(resctrl_online_domains_exist());

        mutex_lock(&rdtgroup_mutex);
        resctrl_fs_teardown();
        mutex_unlock(&rdtgroup_mutex);

        cpus_read_unlock();

        debugfs_remove_recursive(debugfs_resctrl);
        debugfs_resctrl = NULL;
        unregister_filesystem(&rdt_fs_type);

        /*
         * Do not remove the sysfs mount point added by resctrl_init() so that
         * it can be used to umount resctrl.
         */

        resctrl_l3_mon_resource_exit();
        free_rmid_lru_list();
}