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0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * User interface for Resource Allocation in Resource Director Technology(RDT)
0004  *
0005  * Copyright (C) 2016 Intel Corporation
0006  *
0007  * Author: Fenghua Yu <fenghua.yu@intel.com>
0008  *
0009  * More information about RDT be found in the Intel (R) x86 Architecture
0010  * Software Developer Manual.
0011  */
0012 
0013 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0014 
0015 #include <linux/cacheinfo.h>
0016 #include <linux/cpu.h>
0017 #include <linux/debugfs.h>
0018 #include <linux/fs.h>
0019 #include <linux/fs_parser.h>
0020 #include <linux/sysfs.h>
0021 #include <linux/kernfs.h>
0022 #include <linux/seq_buf.h>
0023 #include <linux/seq_file.h>
0024 #include <linux/sched/signal.h>
0025 #include <linux/sched/task.h>
0026 #include <linux/slab.h>
0027 #include <linux/task_work.h>
0028 #include <linux/user_namespace.h>
0029 
0030 #include <uapi/linux/magic.h>
0031 
0032 #include <asm/resctrl.h>
0033 #include "internal.h"
0034 
0035 DEFINE_STATIC_KEY_FALSE(rdt_enable_key);
0036 DEFINE_STATIC_KEY_FALSE(rdt_mon_enable_key);
0037 DEFINE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
0038 static struct kernfs_root *rdt_root;
0039 struct rdtgroup rdtgroup_default;
0040 LIST_HEAD(rdt_all_groups);
0041 
0042 /* list of entries for the schemata file */
0043 LIST_HEAD(resctrl_schema_all);
0044 
0045 /* Kernel fs node for "info" directory under root */
0046 static struct kernfs_node *kn_info;
0047 
0048 /* Kernel fs node for "mon_groups" directory under root */
0049 static struct kernfs_node *kn_mongrp;
0050 
0051 /* Kernel fs node for "mon_data" directory under root */
0052 static struct kernfs_node *kn_mondata;
0053 
0054 static struct seq_buf last_cmd_status;
0055 static char last_cmd_status_buf[512];
0056 
0057 struct dentry *debugfs_resctrl;
0058 
0059 void rdt_last_cmd_clear(void)
0060 {
0061     lockdep_assert_held(&rdtgroup_mutex);
0062     seq_buf_clear(&last_cmd_status);
0063 }
0064 
0065 void rdt_last_cmd_puts(const char *s)
0066 {
0067     lockdep_assert_held(&rdtgroup_mutex);
0068     seq_buf_puts(&last_cmd_status, s);
0069 }
0070 
0071 void rdt_last_cmd_printf(const char *fmt, ...)
0072 {
0073     va_list ap;
0074 
0075     va_start(ap, fmt);
0076     lockdep_assert_held(&rdtgroup_mutex);
0077     seq_buf_vprintf(&last_cmd_status, fmt, ap);
0078     va_end(ap);
0079 }
0080 
0081 /*
0082  * Trivial allocator for CLOSIDs. Since h/w only supports a small number,
0083  * we can keep a bitmap of free CLOSIDs in a single integer.
0084  *
0085  * Using a global CLOSID across all resources has some advantages and
0086  * some drawbacks:
0087  * + We can simply set "current->closid" to assign a task to a resource
0088  *   group.
0089  * + Context switch code can avoid extra memory references deciding which
0090  *   CLOSID to load into the PQR_ASSOC MSR
0091  * - We give up some options in configuring resource groups across multi-socket
0092  *   systems.
0093  * - Our choices on how to configure each resource become progressively more
0094  *   limited as the number of resources grows.
0095  */
0096 static int closid_free_map;
0097 static int closid_free_map_len;
0098 
0099 int closids_supported(void)
0100 {
0101     return closid_free_map_len;
0102 }
0103 
0104 static void closid_init(void)
0105 {
0106     struct resctrl_schema *s;
0107     u32 rdt_min_closid = 32;
0108 
0109     /* Compute rdt_min_closid across all resources */
0110     list_for_each_entry(s, &resctrl_schema_all, list)
0111         rdt_min_closid = min(rdt_min_closid, s->num_closid);
0112 
0113     closid_free_map = BIT_MASK(rdt_min_closid) - 1;
0114 
0115     /* CLOSID 0 is always reserved for the default group */
0116     closid_free_map &= ~1;
0117     closid_free_map_len = rdt_min_closid;
0118 }
0119 
0120 static int closid_alloc(void)
0121 {
0122     u32 closid = ffs(closid_free_map);
0123 
0124     if (closid == 0)
0125         return -ENOSPC;
0126     closid--;
0127     closid_free_map &= ~(1 << closid);
0128 
0129     return closid;
0130 }
0131 
0132 void closid_free(int closid)
0133 {
0134     closid_free_map |= 1 << closid;
0135 }
0136 
0137 /**
0138  * closid_allocated - test if provided closid is in use
0139  * @closid: closid to be tested
0140  *
0141  * Return: true if @closid is currently associated with a resource group,
0142  * false if @closid is free
0143  */
0144 static bool closid_allocated(unsigned int closid)
0145 {
0146     return (closid_free_map & (1 << closid)) == 0;
0147 }
0148 
0149 /**
0150  * rdtgroup_mode_by_closid - Return mode of resource group with closid
0151  * @closid: closid if the resource group
0152  *
0153  * Each resource group is associated with a @closid. Here the mode
0154  * of a resource group can be queried by searching for it using its closid.
0155  *
0156  * Return: mode as &enum rdtgrp_mode of resource group with closid @closid
0157  */
0158 enum rdtgrp_mode rdtgroup_mode_by_closid(int closid)
0159 {
0160     struct rdtgroup *rdtgrp;
0161 
0162     list_for_each_entry(rdtgrp, &rdt_all_groups, rdtgroup_list) {
0163         if (rdtgrp->closid == closid)
0164             return rdtgrp->mode;
0165     }
0166 
0167     return RDT_NUM_MODES;
0168 }
0169 
0170 static const char * const rdt_mode_str[] = {
0171     [RDT_MODE_SHAREABLE]        = "shareable",
0172     [RDT_MODE_EXCLUSIVE]        = "exclusive",
0173     [RDT_MODE_PSEUDO_LOCKSETUP] = "pseudo-locksetup",
0174     [RDT_MODE_PSEUDO_LOCKED]    = "pseudo-locked",
0175 };
0176 
0177 /**
0178  * rdtgroup_mode_str - Return the string representation of mode
0179  * @mode: the resource group mode as &enum rdtgroup_mode
0180  *
0181  * Return: string representation of valid mode, "unknown" otherwise
0182  */
0183 static const char *rdtgroup_mode_str(enum rdtgrp_mode mode)
0184 {
0185     if (mode < RDT_MODE_SHAREABLE || mode >= RDT_NUM_MODES)
0186         return "unknown";
0187 
0188     return rdt_mode_str[mode];
0189 }
0190 
0191 /* set uid and gid of rdtgroup dirs and files to that of the creator */
0192 static int rdtgroup_kn_set_ugid(struct kernfs_node *kn)
0193 {
0194     struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID,
0195                 .ia_uid = current_fsuid(),
0196                 .ia_gid = current_fsgid(), };
0197 
0198     if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) &&
0199         gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID))
0200         return 0;
0201 
0202     return kernfs_setattr(kn, &iattr);
0203 }
0204 
0205 static int rdtgroup_add_file(struct kernfs_node *parent_kn, struct rftype *rft)
0206 {
0207     struct kernfs_node *kn;
0208     int ret;
0209 
0210     kn = __kernfs_create_file(parent_kn, rft->name, rft->mode,
0211                   GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
0212                   0, rft->kf_ops, rft, NULL, NULL);
0213     if (IS_ERR(kn))
0214         return PTR_ERR(kn);
0215 
0216     ret = rdtgroup_kn_set_ugid(kn);
0217     if (ret) {
0218         kernfs_remove(kn);
0219         return ret;
0220     }
0221 
0222     return 0;
0223 }
0224 
0225 static int rdtgroup_seqfile_show(struct seq_file *m, void *arg)
0226 {
0227     struct kernfs_open_file *of = m->private;
0228     struct rftype *rft = of->kn->priv;
0229 
0230     if (rft->seq_show)
0231         return rft->seq_show(of, m, arg);
0232     return 0;
0233 }
0234 
0235 static ssize_t rdtgroup_file_write(struct kernfs_open_file *of, char *buf,
0236                    size_t nbytes, loff_t off)
0237 {
0238     struct rftype *rft = of->kn->priv;
0239 
0240     if (rft->write)
0241         return rft->write(of, buf, nbytes, off);
0242 
0243     return -EINVAL;
0244 }
0245 
0246 static const struct kernfs_ops rdtgroup_kf_single_ops = {
0247     .atomic_write_len   = PAGE_SIZE,
0248     .write          = rdtgroup_file_write,
0249     .seq_show       = rdtgroup_seqfile_show,
0250 };
0251 
0252 static const struct kernfs_ops kf_mondata_ops = {
0253     .atomic_write_len   = PAGE_SIZE,
0254     .seq_show       = rdtgroup_mondata_show,
0255 };
0256 
0257 static bool is_cpu_list(struct kernfs_open_file *of)
0258 {
0259     struct rftype *rft = of->kn->priv;
0260 
0261     return rft->flags & RFTYPE_FLAGS_CPUS_LIST;
0262 }
0263 
0264 static int rdtgroup_cpus_show(struct kernfs_open_file *of,
0265                   struct seq_file *s, void *v)
0266 {
0267     struct rdtgroup *rdtgrp;
0268     struct cpumask *mask;
0269     int ret = 0;
0270 
0271     rdtgrp = rdtgroup_kn_lock_live(of->kn);
0272 
0273     if (rdtgrp) {
0274         if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
0275             if (!rdtgrp->plr->d) {
0276                 rdt_last_cmd_clear();
0277                 rdt_last_cmd_puts("Cache domain offline\n");
0278                 ret = -ENODEV;
0279             } else {
0280                 mask = &rdtgrp->plr->d->cpu_mask;
0281                 seq_printf(s, is_cpu_list(of) ?
0282                        "%*pbl\n" : "%*pb\n",
0283                        cpumask_pr_args(mask));
0284             }
0285         } else {
0286             seq_printf(s, is_cpu_list(of) ? "%*pbl\n" : "%*pb\n",
0287                    cpumask_pr_args(&rdtgrp->cpu_mask));
0288         }
0289     } else {
0290         ret = -ENOENT;
0291     }
0292     rdtgroup_kn_unlock(of->kn);
0293 
0294     return ret;
0295 }
0296 
0297 /*
0298  * This is safe against resctrl_sched_in() called from __switch_to()
0299  * because __switch_to() is executed with interrupts disabled. A local call
0300  * from update_closid_rmid() is protected against __switch_to() because
0301  * preemption is disabled.
0302  */
0303 static void update_cpu_closid_rmid(void *info)
0304 {
0305     struct rdtgroup *r = info;
0306 
0307     if (r) {
0308         this_cpu_write(pqr_state.default_closid, r->closid);
0309         this_cpu_write(pqr_state.default_rmid, r->mon.rmid);
0310     }
0311 
0312     /*
0313      * We cannot unconditionally write the MSR because the current
0314      * executing task might have its own closid selected. Just reuse
0315      * the context switch code.
0316      */
0317     resctrl_sched_in();
0318 }
0319 
0320 /*
0321  * Update the PGR_ASSOC MSR on all cpus in @cpu_mask,
0322  *
0323  * Per task closids/rmids must have been set up before calling this function.
0324  */
0325 static void
0326 update_closid_rmid(const struct cpumask *cpu_mask, struct rdtgroup *r)
0327 {
0328     int cpu = get_cpu();
0329 
0330     if (cpumask_test_cpu(cpu, cpu_mask))
0331         update_cpu_closid_rmid(r);
0332     smp_call_function_many(cpu_mask, update_cpu_closid_rmid, r, 1);
0333     put_cpu();
0334 }
0335 
0336 static int cpus_mon_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,
0337               cpumask_var_t tmpmask)
0338 {
0339     struct rdtgroup *prgrp = rdtgrp->mon.parent, *crgrp;
0340     struct list_head *head;
0341 
0342     /* Check whether cpus belong to parent ctrl group */
0343     cpumask_andnot(tmpmask, newmask, &prgrp->cpu_mask);
0344     if (!cpumask_empty(tmpmask)) {
0345         rdt_last_cmd_puts("Can only add CPUs to mongroup that belong to parent\n");
0346         return -EINVAL;
0347     }
0348 
0349     /* Check whether cpus are dropped from this group */
0350     cpumask_andnot(tmpmask, &rdtgrp->cpu_mask, newmask);
0351     if (!cpumask_empty(tmpmask)) {
0352         /* Give any dropped cpus to parent rdtgroup */
0353         cpumask_or(&prgrp->cpu_mask, &prgrp->cpu_mask, tmpmask);
0354         update_closid_rmid(tmpmask, prgrp);
0355     }
0356 
0357     /*
0358      * If we added cpus, remove them from previous group that owned them
0359      * and update per-cpu rmid
0360      */
0361     cpumask_andnot(tmpmask, newmask, &rdtgrp->cpu_mask);
0362     if (!cpumask_empty(tmpmask)) {
0363         head = &prgrp->mon.crdtgrp_list;
0364         list_for_each_entry(crgrp, head, mon.crdtgrp_list) {
0365             if (crgrp == rdtgrp)
0366                 continue;
0367             cpumask_andnot(&crgrp->cpu_mask, &crgrp->cpu_mask,
0368                        tmpmask);
0369         }
0370         update_closid_rmid(tmpmask, rdtgrp);
0371     }
0372 
0373     /* Done pushing/pulling - update this group with new mask */
0374     cpumask_copy(&rdtgrp->cpu_mask, newmask);
0375 
0376     return 0;
0377 }
0378 
0379 static void cpumask_rdtgrp_clear(struct rdtgroup *r, struct cpumask *m)
0380 {
0381     struct rdtgroup *crgrp;
0382 
0383     cpumask_andnot(&r->cpu_mask, &r->cpu_mask, m);
0384     /* update the child mon group masks as well*/
0385     list_for_each_entry(crgrp, &r->mon.crdtgrp_list, mon.crdtgrp_list)
0386         cpumask_and(&crgrp->cpu_mask, &r->cpu_mask, &crgrp->cpu_mask);
0387 }
0388 
0389 static int cpus_ctrl_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,
0390                cpumask_var_t tmpmask, cpumask_var_t tmpmask1)
0391 {
0392     struct rdtgroup *r, *crgrp;
0393     struct list_head *head;
0394 
0395     /* Check whether cpus are dropped from this group */
0396     cpumask_andnot(tmpmask, &rdtgrp->cpu_mask, newmask);
0397     if (!cpumask_empty(tmpmask)) {
0398         /* Can't drop from default group */
0399         if (rdtgrp == &rdtgroup_default) {
0400             rdt_last_cmd_puts("Can't drop CPUs from default group\n");
0401             return -EINVAL;
0402         }
0403 
0404         /* Give any dropped cpus to rdtgroup_default */
0405         cpumask_or(&rdtgroup_default.cpu_mask,
0406                &rdtgroup_default.cpu_mask, tmpmask);
0407         update_closid_rmid(tmpmask, &rdtgroup_default);
0408     }
0409 
0410     /*
0411      * If we added cpus, remove them from previous group and
0412      * the prev group's child groups that owned them
0413      * and update per-cpu closid/rmid.
0414      */
0415     cpumask_andnot(tmpmask, newmask, &rdtgrp->cpu_mask);
0416     if (!cpumask_empty(tmpmask)) {
0417         list_for_each_entry(r, &rdt_all_groups, rdtgroup_list) {
0418             if (r == rdtgrp)
0419                 continue;
0420             cpumask_and(tmpmask1, &r->cpu_mask, tmpmask);
0421             if (!cpumask_empty(tmpmask1))
0422                 cpumask_rdtgrp_clear(r, tmpmask1);
0423         }
0424         update_closid_rmid(tmpmask, rdtgrp);
0425     }
0426 
0427     /* Done pushing/pulling - update this group with new mask */
0428     cpumask_copy(&rdtgrp->cpu_mask, newmask);
0429 
0430     /*
0431      * Clear child mon group masks since there is a new parent mask
0432      * now and update the rmid for the cpus the child lost.
0433      */
0434     head = &rdtgrp->mon.crdtgrp_list;
0435     list_for_each_entry(crgrp, head, mon.crdtgrp_list) {
0436         cpumask_and(tmpmask, &rdtgrp->cpu_mask, &crgrp->cpu_mask);
0437         update_closid_rmid(tmpmask, rdtgrp);
0438         cpumask_clear(&crgrp->cpu_mask);
0439     }
0440 
0441     return 0;
0442 }
0443 
0444 static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
0445                    char *buf, size_t nbytes, loff_t off)
0446 {
0447     cpumask_var_t tmpmask, newmask, tmpmask1;
0448     struct rdtgroup *rdtgrp;
0449     int ret;
0450 
0451     if (!buf)
0452         return -EINVAL;
0453 
0454     if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL))
0455         return -ENOMEM;
0456     if (!zalloc_cpumask_var(&newmask, GFP_KERNEL)) {
0457         free_cpumask_var(tmpmask);
0458         return -ENOMEM;
0459     }
0460     if (!zalloc_cpumask_var(&tmpmask1, GFP_KERNEL)) {
0461         free_cpumask_var(tmpmask);
0462         free_cpumask_var(newmask);
0463         return -ENOMEM;
0464     }
0465 
0466     rdtgrp = rdtgroup_kn_lock_live(of->kn);
0467     if (!rdtgrp) {
0468         ret = -ENOENT;
0469         goto unlock;
0470     }
0471 
0472     if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED ||
0473         rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
0474         ret = -EINVAL;
0475         rdt_last_cmd_puts("Pseudo-locking in progress\n");
0476         goto unlock;
0477     }
0478 
0479     if (is_cpu_list(of))
0480         ret = cpulist_parse(buf, newmask);
0481     else
0482         ret = cpumask_parse(buf, newmask);
0483 
0484     if (ret) {
0485         rdt_last_cmd_puts("Bad CPU list/mask\n");
0486         goto unlock;
0487     }
0488 
0489     /* check that user didn't specify any offline cpus */
0490     cpumask_andnot(tmpmask, newmask, cpu_online_mask);
0491     if (!cpumask_empty(tmpmask)) {
0492         ret = -EINVAL;
0493         rdt_last_cmd_puts("Can only assign online CPUs\n");
0494         goto unlock;
0495     }
0496 
0497     if (rdtgrp->type == RDTCTRL_GROUP)
0498         ret = cpus_ctrl_write(rdtgrp, newmask, tmpmask, tmpmask1);
0499     else if (rdtgrp->type == RDTMON_GROUP)
0500         ret = cpus_mon_write(rdtgrp, newmask, tmpmask);
0501     else
0502         ret = -EINVAL;
0503 
0504 unlock:
0505     rdtgroup_kn_unlock(of->kn);
0506     free_cpumask_var(tmpmask);
0507     free_cpumask_var(newmask);
0508     free_cpumask_var(tmpmask1);
0509 
0510     return ret ?: nbytes;
0511 }
0512 
0513 /**
0514  * rdtgroup_remove - the helper to remove resource group safely
0515  * @rdtgrp: resource group to remove
0516  *
0517  * On resource group creation via a mkdir, an extra kernfs_node reference is
0518  * taken to ensure that the rdtgroup structure remains accessible for the
0519  * rdtgroup_kn_unlock() calls where it is removed.
0520  *
0521  * Drop the extra reference here, then free the rdtgroup structure.
0522  *
0523  * Return: void
0524  */
0525 static void rdtgroup_remove(struct rdtgroup *rdtgrp)
0526 {
0527     kernfs_put(rdtgrp->kn);
0528     kfree(rdtgrp);
0529 }
0530 
0531 static void _update_task_closid_rmid(void *task)
0532 {
0533     /*
0534      * If the task is still current on this CPU, update PQR_ASSOC MSR.
0535      * Otherwise, the MSR is updated when the task is scheduled in.
0536      */
0537     if (task == current)
0538         resctrl_sched_in();
0539 }
0540 
0541 static void update_task_closid_rmid(struct task_struct *t)
0542 {
0543     if (IS_ENABLED(CONFIG_SMP) && task_curr(t))
0544         smp_call_function_single(task_cpu(t), _update_task_closid_rmid, t, 1);
0545     else
0546         _update_task_closid_rmid(t);
0547 }
0548 
0549 static int __rdtgroup_move_task(struct task_struct *tsk,
0550                 struct rdtgroup *rdtgrp)
0551 {
0552     /* If the task is already in rdtgrp, no need to move the task. */
0553     if ((rdtgrp->type == RDTCTRL_GROUP && tsk->closid == rdtgrp->closid &&
0554          tsk->rmid == rdtgrp->mon.rmid) ||
0555         (rdtgrp->type == RDTMON_GROUP && tsk->rmid == rdtgrp->mon.rmid &&
0556          tsk->closid == rdtgrp->mon.parent->closid))
0557         return 0;
0558 
0559     /*
0560      * Set the task's closid/rmid before the PQR_ASSOC MSR can be
0561      * updated by them.
0562      *
0563      * For ctrl_mon groups, move both closid and rmid.
0564      * For monitor groups, can move the tasks only from
0565      * their parent CTRL group.
0566      */
0567 
0568     if (rdtgrp->type == RDTCTRL_GROUP) {
0569         WRITE_ONCE(tsk->closid, rdtgrp->closid);
0570         WRITE_ONCE(tsk->rmid, rdtgrp->mon.rmid);
0571     } else if (rdtgrp->type == RDTMON_GROUP) {
0572         if (rdtgrp->mon.parent->closid == tsk->closid) {
0573             WRITE_ONCE(tsk->rmid, rdtgrp->mon.rmid);
0574         } else {
0575             rdt_last_cmd_puts("Can't move task to different control group\n");
0576             return -EINVAL;
0577         }
0578     }
0579 
0580     /*
0581      * Ensure the task's closid and rmid are written before determining if
0582      * the task is current that will decide if it will be interrupted.
0583      */
0584     barrier();
0585 
0586     /*
0587      * By now, the task's closid and rmid are set. If the task is current
0588      * on a CPU, the PQR_ASSOC MSR needs to be updated to make the resource
0589      * group go into effect. If the task is not current, the MSR will be
0590      * updated when the task is scheduled in.
0591      */
0592     update_task_closid_rmid(tsk);
0593 
0594     return 0;
0595 }
0596 
0597 static bool is_closid_match(struct task_struct *t, struct rdtgroup *r)
0598 {
0599     return (rdt_alloc_capable &&
0600            (r->type == RDTCTRL_GROUP) && (t->closid == r->closid));
0601 }
0602 
0603 static bool is_rmid_match(struct task_struct *t, struct rdtgroup *r)
0604 {
0605     return (rdt_mon_capable &&
0606            (r->type == RDTMON_GROUP) && (t->rmid == r->mon.rmid));
0607 }
0608 
0609 /**
0610  * rdtgroup_tasks_assigned - Test if tasks have been assigned to resource group
0611  * @r: Resource group
0612  *
0613  * Return: 1 if tasks have been assigned to @r, 0 otherwise
0614  */
0615 int rdtgroup_tasks_assigned(struct rdtgroup *r)
0616 {
0617     struct task_struct *p, *t;
0618     int ret = 0;
0619 
0620     lockdep_assert_held(&rdtgroup_mutex);
0621 
0622     rcu_read_lock();
0623     for_each_process_thread(p, t) {
0624         if (is_closid_match(t, r) || is_rmid_match(t, r)) {
0625             ret = 1;
0626             break;
0627         }
0628     }
0629     rcu_read_unlock();
0630 
0631     return ret;
0632 }
0633 
0634 static int rdtgroup_task_write_permission(struct task_struct *task,
0635                       struct kernfs_open_file *of)
0636 {
0637     const struct cred *tcred = get_task_cred(task);
0638     const struct cred *cred = current_cred();
0639     int ret = 0;
0640 
0641     /*
0642      * Even if we're attaching all tasks in the thread group, we only
0643      * need to check permissions on one of them.
0644      */
0645     if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
0646         !uid_eq(cred->euid, tcred->uid) &&
0647         !uid_eq(cred->euid, tcred->suid)) {
0648         rdt_last_cmd_printf("No permission to move task %d\n", task->pid);
0649         ret = -EPERM;
0650     }
0651 
0652     put_cred(tcred);
0653     return ret;
0654 }
0655 
0656 static int rdtgroup_move_task(pid_t pid, struct rdtgroup *rdtgrp,
0657                   struct kernfs_open_file *of)
0658 {
0659     struct task_struct *tsk;
0660     int ret;
0661 
0662     rcu_read_lock();
0663     if (pid) {
0664         tsk = find_task_by_vpid(pid);
0665         if (!tsk) {
0666             rcu_read_unlock();
0667             rdt_last_cmd_printf("No task %d\n", pid);
0668             return -ESRCH;
0669         }
0670     } else {
0671         tsk = current;
0672     }
0673 
0674     get_task_struct(tsk);
0675     rcu_read_unlock();
0676 
0677     ret = rdtgroup_task_write_permission(tsk, of);
0678     if (!ret)
0679         ret = __rdtgroup_move_task(tsk, rdtgrp);
0680 
0681     put_task_struct(tsk);
0682     return ret;
0683 }
0684 
0685 static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
0686                     char *buf, size_t nbytes, loff_t off)
0687 {
0688     struct rdtgroup *rdtgrp;
0689     int ret = 0;
0690     pid_t pid;
0691 
0692     if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
0693         return -EINVAL;
0694     rdtgrp = rdtgroup_kn_lock_live(of->kn);
0695     if (!rdtgrp) {
0696         rdtgroup_kn_unlock(of->kn);
0697         return -ENOENT;
0698     }
0699     rdt_last_cmd_clear();
0700 
0701     if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED ||
0702         rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
0703         ret = -EINVAL;
0704         rdt_last_cmd_puts("Pseudo-locking in progress\n");
0705         goto unlock;
0706     }
0707 
0708     ret = rdtgroup_move_task(pid, rdtgrp, of);
0709 
0710 unlock:
0711     rdtgroup_kn_unlock(of->kn);
0712 
0713     return ret ?: nbytes;
0714 }
0715 
0716 static void show_rdt_tasks(struct rdtgroup *r, struct seq_file *s)
0717 {
0718     struct task_struct *p, *t;
0719 
0720     rcu_read_lock();
0721     for_each_process_thread(p, t) {
0722         if (is_closid_match(t, r) || is_rmid_match(t, r))
0723             seq_printf(s, "%d\n", t->pid);
0724     }
0725     rcu_read_unlock();
0726 }
0727 
0728 static int rdtgroup_tasks_show(struct kernfs_open_file *of,
0729                    struct seq_file *s, void *v)
0730 {
0731     struct rdtgroup *rdtgrp;
0732     int ret = 0;
0733 
0734     rdtgrp = rdtgroup_kn_lock_live(of->kn);
0735     if (rdtgrp)
0736         show_rdt_tasks(rdtgrp, s);
0737     else
0738         ret = -ENOENT;
0739     rdtgroup_kn_unlock(of->kn);
0740 
0741     return ret;
0742 }
0743 
0744 #ifdef CONFIG_PROC_CPU_RESCTRL
0745 
0746 /*
0747  * A task can only be part of one resctrl control group and of one monitor
0748  * group which is associated to that control group.
0749  *
0750  * 1)   res:
0751  *      mon:
0752  *
0753  *    resctrl is not available.
0754  *
0755  * 2)   res:/
0756  *      mon:
0757  *
0758  *    Task is part of the root resctrl control group, and it is not associated
0759  *    to any monitor group.
0760  *
0761  * 3)  res:/
0762  *     mon:mon0
0763  *
0764  *    Task is part of the root resctrl control group and monitor group mon0.
0765  *
0766  * 4)  res:group0
0767  *     mon:
0768  *
0769  *    Task is part of resctrl control group group0, and it is not associated
0770  *    to any monitor group.
0771  *
0772  * 5) res:group0
0773  *    mon:mon1
0774  *
0775  *    Task is part of resctrl control group group0 and monitor group mon1.
0776  */
0777 int proc_resctrl_show(struct seq_file *s, struct pid_namespace *ns,
0778               struct pid *pid, struct task_struct *tsk)
0779 {
0780     struct rdtgroup *rdtg;
0781     int ret = 0;
0782 
0783     mutex_lock(&rdtgroup_mutex);
0784 
0785     /* Return empty if resctrl has not been mounted. */
0786     if (!static_branch_unlikely(&rdt_enable_key)) {
0787         seq_puts(s, "res:\nmon:\n");
0788         goto unlock;
0789     }
0790 
0791     list_for_each_entry(rdtg, &rdt_all_groups, rdtgroup_list) {
0792         struct rdtgroup *crg;
0793 
0794         /*
0795          * Task information is only relevant for shareable
0796          * and exclusive groups.
0797          */
0798         if (rdtg->mode != RDT_MODE_SHAREABLE &&
0799             rdtg->mode != RDT_MODE_EXCLUSIVE)
0800             continue;
0801 
0802         if (rdtg->closid != tsk->closid)
0803             continue;
0804 
0805         seq_printf(s, "res:%s%s\n", (rdtg == &rdtgroup_default) ? "/" : "",
0806                rdtg->kn->name);
0807         seq_puts(s, "mon:");
0808         list_for_each_entry(crg, &rdtg->mon.crdtgrp_list,
0809                     mon.crdtgrp_list) {
0810             if (tsk->rmid != crg->mon.rmid)
0811                 continue;
0812             seq_printf(s, "%s", crg->kn->name);
0813             break;
0814         }
0815         seq_putc(s, '\n');
0816         goto unlock;
0817     }
0818     /*
0819      * The above search should succeed. Otherwise return
0820      * with an error.
0821      */
0822     ret = -ENOENT;
0823 unlock:
0824     mutex_unlock(&rdtgroup_mutex);
0825 
0826     return ret;
0827 }
0828 #endif
0829 
0830 static int rdt_last_cmd_status_show(struct kernfs_open_file *of,
0831                     struct seq_file *seq, void *v)
0832 {
0833     int len;
0834 
0835     mutex_lock(&rdtgroup_mutex);
0836     len = seq_buf_used(&last_cmd_status);
0837     if (len)
0838         seq_printf(seq, "%.*s", len, last_cmd_status_buf);
0839     else
0840         seq_puts(seq, "ok\n");
0841     mutex_unlock(&rdtgroup_mutex);
0842     return 0;
0843 }
0844 
0845 static int rdt_num_closids_show(struct kernfs_open_file *of,
0846                 struct seq_file *seq, void *v)
0847 {
0848     struct resctrl_schema *s = of->kn->parent->priv;
0849 
0850     seq_printf(seq, "%u\n", s->num_closid);
0851     return 0;
0852 }
0853 
0854 static int rdt_default_ctrl_show(struct kernfs_open_file *of,
0855                  struct seq_file *seq, void *v)
0856 {
0857     struct resctrl_schema *s = of->kn->parent->priv;
0858     struct rdt_resource *r = s->res;
0859 
0860     seq_printf(seq, "%x\n", r->default_ctrl);
0861     return 0;
0862 }
0863 
0864 static int rdt_min_cbm_bits_show(struct kernfs_open_file *of,
0865                  struct seq_file *seq, void *v)
0866 {
0867     struct resctrl_schema *s = of->kn->parent->priv;
0868     struct rdt_resource *r = s->res;
0869 
0870     seq_printf(seq, "%u\n", r->cache.min_cbm_bits);
0871     return 0;
0872 }
0873 
0874 static int rdt_shareable_bits_show(struct kernfs_open_file *of,
0875                    struct seq_file *seq, void *v)
0876 {
0877     struct resctrl_schema *s = of->kn->parent->priv;
0878     struct rdt_resource *r = s->res;
0879 
0880     seq_printf(seq, "%x\n", r->cache.shareable_bits);
0881     return 0;
0882 }
0883 
0884 /**
0885  * rdt_bit_usage_show - Display current usage of resources
0886  *
0887  * A domain is a shared resource that can now be allocated differently. Here
0888  * we display the current regions of the domain as an annotated bitmask.
0889  * For each domain of this resource its allocation bitmask
0890  * is annotated as below to indicate the current usage of the corresponding bit:
0891  *   0 - currently unused
0892  *   X - currently available for sharing and used by software and hardware
0893  *   H - currently used by hardware only but available for software use
0894  *   S - currently used and shareable by software only
0895  *   E - currently used exclusively by one resource group
0896  *   P - currently pseudo-locked by one resource group
0897  */
0898 static int rdt_bit_usage_show(struct kernfs_open_file *of,
0899                   struct seq_file *seq, void *v)
0900 {
0901     struct resctrl_schema *s = of->kn->parent->priv;
0902     /*
0903      * Use unsigned long even though only 32 bits are used to ensure
0904      * test_bit() is used safely.
0905      */
0906     unsigned long sw_shareable = 0, hw_shareable = 0;
0907     unsigned long exclusive = 0, pseudo_locked = 0;
0908     struct rdt_resource *r = s->res;
0909     struct rdt_domain *dom;
0910     int i, hwb, swb, excl, psl;
0911     enum rdtgrp_mode mode;
0912     bool sep = false;
0913     u32 ctrl_val;
0914 
0915     mutex_lock(&rdtgroup_mutex);
0916     hw_shareable = r->cache.shareable_bits;
0917     list_for_each_entry(dom, &r->domains, list) {
0918         if (sep)
0919             seq_putc(seq, ';');
0920         sw_shareable = 0;
0921         exclusive = 0;
0922         seq_printf(seq, "%d=", dom->id);
0923         for (i = 0; i < closids_supported(); i++) {
0924             if (!closid_allocated(i))
0925                 continue;
0926             ctrl_val = resctrl_arch_get_config(r, dom, i,
0927                                s->conf_type);
0928             mode = rdtgroup_mode_by_closid(i);
0929             switch (mode) {
0930             case RDT_MODE_SHAREABLE:
0931                 sw_shareable |= ctrl_val;
0932                 break;
0933             case RDT_MODE_EXCLUSIVE:
0934                 exclusive |= ctrl_val;
0935                 break;
0936             case RDT_MODE_PSEUDO_LOCKSETUP:
0937             /*
0938              * RDT_MODE_PSEUDO_LOCKSETUP is possible
0939              * here but not included since the CBM
0940              * associated with this CLOSID in this mode
0941              * is not initialized and no task or cpu can be
0942              * assigned this CLOSID.
0943              */
0944                 break;
0945             case RDT_MODE_PSEUDO_LOCKED:
0946             case RDT_NUM_MODES:
0947                 WARN(1,
0948                      "invalid mode for closid %d\n", i);
0949                 break;
0950             }
0951         }
0952         for (i = r->cache.cbm_len - 1; i >= 0; i--) {
0953             pseudo_locked = dom->plr ? dom->plr->cbm : 0;
0954             hwb = test_bit(i, &hw_shareable);
0955             swb = test_bit(i, &sw_shareable);
0956             excl = test_bit(i, &exclusive);
0957             psl = test_bit(i, &pseudo_locked);
0958             if (hwb && swb)
0959                 seq_putc(seq, 'X');
0960             else if (hwb && !swb)
0961                 seq_putc(seq, 'H');
0962             else if (!hwb && swb)
0963                 seq_putc(seq, 'S');
0964             else if (excl)
0965                 seq_putc(seq, 'E');
0966             else if (psl)
0967                 seq_putc(seq, 'P');
0968             else /* Unused bits remain */
0969                 seq_putc(seq, '0');
0970         }
0971         sep = true;
0972     }
0973     seq_putc(seq, '\n');
0974     mutex_unlock(&rdtgroup_mutex);
0975     return 0;
0976 }
0977 
0978 static int rdt_min_bw_show(struct kernfs_open_file *of,
0979                  struct seq_file *seq, void *v)
0980 {
0981     struct resctrl_schema *s = of->kn->parent->priv;
0982     struct rdt_resource *r = s->res;
0983 
0984     seq_printf(seq, "%u\n", r->membw.min_bw);
0985     return 0;
0986 }
0987 
0988 static int rdt_num_rmids_show(struct kernfs_open_file *of,
0989                   struct seq_file *seq, void *v)
0990 {
0991     struct rdt_resource *r = of->kn->parent->priv;
0992 
0993     seq_printf(seq, "%d\n", r->num_rmid);
0994 
0995     return 0;
0996 }
0997 
0998 static int rdt_mon_features_show(struct kernfs_open_file *of,
0999                  struct seq_file *seq, void *v)
1000 {
1001     struct rdt_resource *r = of->kn->parent->priv;
1002     struct mon_evt *mevt;
1003 
1004     list_for_each_entry(mevt, &r->evt_list, list)
1005         seq_printf(seq, "%s\n", mevt->name);
1006 
1007     return 0;
1008 }
1009 
1010 static int rdt_bw_gran_show(struct kernfs_open_file *of,
1011                  struct seq_file *seq, void *v)
1012 {
1013     struct resctrl_schema *s = of->kn->parent->priv;
1014     struct rdt_resource *r = s->res;
1015 
1016     seq_printf(seq, "%u\n", r->membw.bw_gran);
1017     return 0;
1018 }
1019 
1020 static int rdt_delay_linear_show(struct kernfs_open_file *of,
1021                  struct seq_file *seq, void *v)
1022 {
1023     struct resctrl_schema *s = of->kn->parent->priv;
1024     struct rdt_resource *r = s->res;
1025 
1026     seq_printf(seq, "%u\n", r->membw.delay_linear);
1027     return 0;
1028 }
1029 
1030 static int max_threshold_occ_show(struct kernfs_open_file *of,
1031                   struct seq_file *seq, void *v)
1032 {
1033     struct rdt_resource *r = of->kn->parent->priv;
1034     struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
1035 
1036     seq_printf(seq, "%u\n", resctrl_cqm_threshold * hw_res->mon_scale);
1037 
1038     return 0;
1039 }
1040 
1041 static int rdt_thread_throttle_mode_show(struct kernfs_open_file *of,
1042                      struct seq_file *seq, void *v)
1043 {
1044     struct resctrl_schema *s = of->kn->parent->priv;
1045     struct rdt_resource *r = s->res;
1046 
1047     if (r->membw.throttle_mode == THREAD_THROTTLE_PER_THREAD)
1048         seq_puts(seq, "per-thread\n");
1049     else
1050         seq_puts(seq, "max\n");
1051 
1052     return 0;
1053 }
1054 
1055 static ssize_t max_threshold_occ_write(struct kernfs_open_file *of,
1056                        char *buf, size_t nbytes, loff_t off)
1057 {
1058     struct rdt_hw_resource *hw_res;
1059     unsigned int bytes;
1060     int ret;
1061 
1062     ret = kstrtouint(buf, 0, &bytes);
1063     if (ret)
1064         return ret;
1065 
1066     if (bytes > (boot_cpu_data.x86_cache_size * 1024))
1067         return -EINVAL;
1068 
1069     hw_res = resctrl_to_arch_res(of->kn->parent->priv);
1070     resctrl_cqm_threshold = bytes / hw_res->mon_scale;
1071 
1072     return nbytes;
1073 }
1074 
1075 /*
1076  * rdtgroup_mode_show - Display mode of this resource group
1077  */
1078 static int rdtgroup_mode_show(struct kernfs_open_file *of,
1079                   struct seq_file *s, void *v)
1080 {
1081     struct rdtgroup *rdtgrp;
1082 
1083     rdtgrp = rdtgroup_kn_lock_live(of->kn);
1084     if (!rdtgrp) {
1085         rdtgroup_kn_unlock(of->kn);
1086         return -ENOENT;
1087     }
1088 
1089     seq_printf(s, "%s\n", rdtgroup_mode_str(rdtgrp->mode));
1090 
1091     rdtgroup_kn_unlock(of->kn);
1092     return 0;
1093 }
1094 
1095 static enum resctrl_conf_type resctrl_peer_type(enum resctrl_conf_type my_type)
1096 {
1097     switch (my_type) {
1098     case CDP_CODE:
1099         return CDP_DATA;
1100     case CDP_DATA:
1101         return CDP_CODE;
1102     default:
1103     case CDP_NONE:
1104         return CDP_NONE;
1105     }
1106 }
1107 
1108 /**
1109  * __rdtgroup_cbm_overlaps - Does CBM for intended closid overlap with other
1110  * @r: Resource to which domain instance @d belongs.
1111  * @d: The domain instance for which @closid is being tested.
1112  * @cbm: Capacity bitmask being tested.
1113  * @closid: Intended closid for @cbm.
1114  * @exclusive: Only check if overlaps with exclusive resource groups
1115  *
1116  * Checks if provided @cbm intended to be used for @closid on domain
1117  * @d overlaps with any other closids or other hardware usage associated
1118  * with this domain. If @exclusive is true then only overlaps with
1119  * resource groups in exclusive mode will be considered. If @exclusive
1120  * is false then overlaps with any resource group or hardware entities
1121  * will be considered.
1122  *
1123  * @cbm is unsigned long, even if only 32 bits are used, to make the
1124  * bitmap functions work correctly.
1125  *
1126  * Return: false if CBM does not overlap, true if it does.
1127  */
1128 static bool __rdtgroup_cbm_overlaps(struct rdt_resource *r, struct rdt_domain *d,
1129                     unsigned long cbm, int closid,
1130                     enum resctrl_conf_type type, bool exclusive)
1131 {
1132     enum rdtgrp_mode mode;
1133     unsigned long ctrl_b;
1134     int i;
1135 
1136     /* Check for any overlap with regions used by hardware directly */
1137     if (!exclusive) {
1138         ctrl_b = r->cache.shareable_bits;
1139         if (bitmap_intersects(&cbm, &ctrl_b, r->cache.cbm_len))
1140             return true;
1141     }
1142 
1143     /* Check for overlap with other resource groups */
1144     for (i = 0; i < closids_supported(); i++) {
1145         ctrl_b = resctrl_arch_get_config(r, d, i, type);
1146         mode = rdtgroup_mode_by_closid(i);
1147         if (closid_allocated(i) && i != closid &&
1148             mode != RDT_MODE_PSEUDO_LOCKSETUP) {
1149             if (bitmap_intersects(&cbm, &ctrl_b, r->cache.cbm_len)) {
1150                 if (exclusive) {
1151                     if (mode == RDT_MODE_EXCLUSIVE)
1152                         return true;
1153                     continue;
1154                 }
1155                 return true;
1156             }
1157         }
1158     }
1159 
1160     return false;
1161 }
1162 
1163 /**
1164  * rdtgroup_cbm_overlaps - Does CBM overlap with other use of hardware
1165  * @s: Schema for the resource to which domain instance @d belongs.
1166  * @d: The domain instance for which @closid is being tested.
1167  * @cbm: Capacity bitmask being tested.
1168  * @closid: Intended closid for @cbm.
1169  * @exclusive: Only check if overlaps with exclusive resource groups
1170  *
1171  * Resources that can be allocated using a CBM can use the CBM to control
1172  * the overlap of these allocations. rdtgroup_cmb_overlaps() is the test
1173  * for overlap. Overlap test is not limited to the specific resource for
1174  * which the CBM is intended though - when dealing with CDP resources that
1175  * share the underlying hardware the overlap check should be performed on
1176  * the CDP resource sharing the hardware also.
1177  *
1178  * Refer to description of __rdtgroup_cbm_overlaps() for the details of the
1179  * overlap test.
1180  *
1181  * Return: true if CBM overlap detected, false if there is no overlap
1182  */
1183 bool rdtgroup_cbm_overlaps(struct resctrl_schema *s, struct rdt_domain *d,
1184                unsigned long cbm, int closid, bool exclusive)
1185 {
1186     enum resctrl_conf_type peer_type = resctrl_peer_type(s->conf_type);
1187     struct rdt_resource *r = s->res;
1188 
1189     if (__rdtgroup_cbm_overlaps(r, d, cbm, closid, s->conf_type,
1190                     exclusive))
1191         return true;
1192 
1193     if (!resctrl_arch_get_cdp_enabled(r->rid))
1194         return false;
1195     return  __rdtgroup_cbm_overlaps(r, d, cbm, closid, peer_type, exclusive);
1196 }
1197 
1198 /**
1199  * rdtgroup_mode_test_exclusive - Test if this resource group can be exclusive
1200  *
1201  * An exclusive resource group implies that there should be no sharing of
1202  * its allocated resources. At the time this group is considered to be
1203  * exclusive this test can determine if its current schemata supports this
1204  * setting by testing for overlap with all other resource groups.
1205  *
1206  * Return: true if resource group can be exclusive, false if there is overlap
1207  * with allocations of other resource groups and thus this resource group
1208  * cannot be exclusive.
1209  */
1210 static bool rdtgroup_mode_test_exclusive(struct rdtgroup *rdtgrp)
1211 {
1212     int closid = rdtgrp->closid;
1213     struct resctrl_schema *s;
1214     struct rdt_resource *r;
1215     bool has_cache = false;
1216     struct rdt_domain *d;
1217     u32 ctrl;
1218 
1219     list_for_each_entry(s, &resctrl_schema_all, list) {
1220         r = s->res;
1221         if (r->rid == RDT_RESOURCE_MBA)
1222             continue;
1223         has_cache = true;
1224         list_for_each_entry(d, &r->domains, list) {
1225             ctrl = resctrl_arch_get_config(r, d, closid,
1226                                s->conf_type);
1227             if (rdtgroup_cbm_overlaps(s, d, ctrl, closid, false)) {
1228                 rdt_last_cmd_puts("Schemata overlaps\n");
1229                 return false;
1230             }
1231         }
1232     }
1233 
1234     if (!has_cache) {
1235         rdt_last_cmd_puts("Cannot be exclusive without CAT/CDP\n");
1236         return false;
1237     }
1238 
1239     return true;
1240 }
1241 
1242 /**
1243  * rdtgroup_mode_write - Modify the resource group's mode
1244  *
1245  */
1246 static ssize_t rdtgroup_mode_write(struct kernfs_open_file *of,
1247                    char *buf, size_t nbytes, loff_t off)
1248 {
1249     struct rdtgroup *rdtgrp;
1250     enum rdtgrp_mode mode;
1251     int ret = 0;
1252 
1253     /* Valid input requires a trailing newline */
1254     if (nbytes == 0 || buf[nbytes - 1] != '\n')
1255         return -EINVAL;
1256     buf[nbytes - 1] = '\0';
1257 
1258     rdtgrp = rdtgroup_kn_lock_live(of->kn);
1259     if (!rdtgrp) {
1260         rdtgroup_kn_unlock(of->kn);
1261         return -ENOENT;
1262     }
1263 
1264     rdt_last_cmd_clear();
1265 
1266     mode = rdtgrp->mode;
1267 
1268     if ((!strcmp(buf, "shareable") && mode == RDT_MODE_SHAREABLE) ||
1269         (!strcmp(buf, "exclusive") && mode == RDT_MODE_EXCLUSIVE) ||
1270         (!strcmp(buf, "pseudo-locksetup") &&
1271          mode == RDT_MODE_PSEUDO_LOCKSETUP) ||
1272         (!strcmp(buf, "pseudo-locked") && mode == RDT_MODE_PSEUDO_LOCKED))
1273         goto out;
1274 
1275     if (mode == RDT_MODE_PSEUDO_LOCKED) {
1276         rdt_last_cmd_puts("Cannot change pseudo-locked group\n");
1277         ret = -EINVAL;
1278         goto out;
1279     }
1280 
1281     if (!strcmp(buf, "shareable")) {
1282         if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
1283             ret = rdtgroup_locksetup_exit(rdtgrp);
1284             if (ret)
1285                 goto out;
1286         }
1287         rdtgrp->mode = RDT_MODE_SHAREABLE;
1288     } else if (!strcmp(buf, "exclusive")) {
1289         if (!rdtgroup_mode_test_exclusive(rdtgrp)) {
1290             ret = -EINVAL;
1291             goto out;
1292         }
1293         if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
1294             ret = rdtgroup_locksetup_exit(rdtgrp);
1295             if (ret)
1296                 goto out;
1297         }
1298         rdtgrp->mode = RDT_MODE_EXCLUSIVE;
1299     } else if (!strcmp(buf, "pseudo-locksetup")) {
1300         ret = rdtgroup_locksetup_enter(rdtgrp);
1301         if (ret)
1302             goto out;
1303         rdtgrp->mode = RDT_MODE_PSEUDO_LOCKSETUP;
1304     } else {
1305         rdt_last_cmd_puts("Unknown or unsupported mode\n");
1306         ret = -EINVAL;
1307     }
1308 
1309 out:
1310     rdtgroup_kn_unlock(of->kn);
1311     return ret ?: nbytes;
1312 }
1313 
1314 /**
1315  * rdtgroup_cbm_to_size - Translate CBM to size in bytes
1316  * @r: RDT resource to which @d belongs.
1317  * @d: RDT domain instance.
1318  * @cbm: bitmask for which the size should be computed.
1319  *
1320  * The bitmask provided associated with the RDT domain instance @d will be
1321  * translated into how many bytes it represents. The size in bytes is
1322  * computed by first dividing the total cache size by the CBM length to
1323  * determine how many bytes each bit in the bitmask represents. The result
1324  * is multiplied with the number of bits set in the bitmask.
1325  *
1326  * @cbm is unsigned long, even if only 32 bits are used to make the
1327  * bitmap functions work correctly.
1328  */
1329 unsigned int rdtgroup_cbm_to_size(struct rdt_resource *r,
1330                   struct rdt_domain *d, unsigned long cbm)
1331 {
1332     struct cpu_cacheinfo *ci;
1333     unsigned int size = 0;
1334     int num_b, i;
1335 
1336     num_b = bitmap_weight(&cbm, r->cache.cbm_len);
1337     ci = get_cpu_cacheinfo(cpumask_any(&d->cpu_mask));
1338     for (i = 0; i < ci->num_leaves; i++) {
1339         if (ci->info_list[i].level == r->cache_level) {
1340             size = ci->info_list[i].size / r->cache.cbm_len * num_b;
1341             break;
1342         }
1343     }
1344 
1345     return size;
1346 }
1347 
1348 /**
1349  * rdtgroup_size_show - Display size in bytes of allocated regions
1350  *
1351  * The "size" file mirrors the layout of the "schemata" file, printing the
1352  * size in bytes of each region instead of the capacity bitmask.
1353  *
1354  */
1355 static int rdtgroup_size_show(struct kernfs_open_file *of,
1356                   struct seq_file *s, void *v)
1357 {
1358     struct resctrl_schema *schema;
1359     struct rdtgroup *rdtgrp;
1360     struct rdt_resource *r;
1361     struct rdt_domain *d;
1362     unsigned int size;
1363     int ret = 0;
1364     bool sep;
1365     u32 ctrl;
1366 
1367     rdtgrp = rdtgroup_kn_lock_live(of->kn);
1368     if (!rdtgrp) {
1369         rdtgroup_kn_unlock(of->kn);
1370         return -ENOENT;
1371     }
1372 
1373     if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
1374         if (!rdtgrp->plr->d) {
1375             rdt_last_cmd_clear();
1376             rdt_last_cmd_puts("Cache domain offline\n");
1377             ret = -ENODEV;
1378         } else {
1379             seq_printf(s, "%*s:", max_name_width,
1380                    rdtgrp->plr->s->name);
1381             size = rdtgroup_cbm_to_size(rdtgrp->plr->s->res,
1382                             rdtgrp->plr->d,
1383                             rdtgrp->plr->cbm);
1384             seq_printf(s, "%d=%u\n", rdtgrp->plr->d->id, size);
1385         }
1386         goto out;
1387     }
1388 
1389     list_for_each_entry(schema, &resctrl_schema_all, list) {
1390         r = schema->res;
1391         sep = false;
1392         seq_printf(s, "%*s:", max_name_width, schema->name);
1393         list_for_each_entry(d, &r->domains, list) {
1394             if (sep)
1395                 seq_putc(s, ';');
1396             if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
1397                 size = 0;
1398             } else {
1399                 ctrl = resctrl_arch_get_config(r, d,
1400                                    rdtgrp->closid,
1401                                    schema->conf_type);
1402                 if (r->rid == RDT_RESOURCE_MBA)
1403                     size = ctrl;
1404                 else
1405                     size = rdtgroup_cbm_to_size(r, d, ctrl);
1406             }
1407             seq_printf(s, "%d=%u", d->id, size);
1408             sep = true;
1409         }
1410         seq_putc(s, '\n');
1411     }
1412 
1413 out:
1414     rdtgroup_kn_unlock(of->kn);
1415 
1416     return ret;
1417 }
1418 
1419 /* rdtgroup information files for one cache resource. */
1420 static struct rftype res_common_files[] = {
1421     {
1422         .name       = "last_cmd_status",
1423         .mode       = 0444,
1424         .kf_ops     = &rdtgroup_kf_single_ops,
1425         .seq_show   = rdt_last_cmd_status_show,
1426         .fflags     = RF_TOP_INFO,
1427     },
1428     {
1429         .name       = "num_closids",
1430         .mode       = 0444,
1431         .kf_ops     = &rdtgroup_kf_single_ops,
1432         .seq_show   = rdt_num_closids_show,
1433         .fflags     = RF_CTRL_INFO,
1434     },
1435     {
1436         .name       = "mon_features",
1437         .mode       = 0444,
1438         .kf_ops     = &rdtgroup_kf_single_ops,
1439         .seq_show   = rdt_mon_features_show,
1440         .fflags     = RF_MON_INFO,
1441     },
1442     {
1443         .name       = "num_rmids",
1444         .mode       = 0444,
1445         .kf_ops     = &rdtgroup_kf_single_ops,
1446         .seq_show   = rdt_num_rmids_show,
1447         .fflags     = RF_MON_INFO,
1448     },
1449     {
1450         .name       = "cbm_mask",
1451         .mode       = 0444,
1452         .kf_ops     = &rdtgroup_kf_single_ops,
1453         .seq_show   = rdt_default_ctrl_show,
1454         .fflags     = RF_CTRL_INFO | RFTYPE_RES_CACHE,
1455     },
1456     {
1457         .name       = "min_cbm_bits",
1458         .mode       = 0444,
1459         .kf_ops     = &rdtgroup_kf_single_ops,
1460         .seq_show   = rdt_min_cbm_bits_show,
1461         .fflags     = RF_CTRL_INFO | RFTYPE_RES_CACHE,
1462     },
1463     {
1464         .name       = "shareable_bits",
1465         .mode       = 0444,
1466         .kf_ops     = &rdtgroup_kf_single_ops,
1467         .seq_show   = rdt_shareable_bits_show,
1468         .fflags     = RF_CTRL_INFO | RFTYPE_RES_CACHE,
1469     },
1470     {
1471         .name       = "bit_usage",
1472         .mode       = 0444,
1473         .kf_ops     = &rdtgroup_kf_single_ops,
1474         .seq_show   = rdt_bit_usage_show,
1475         .fflags     = RF_CTRL_INFO | RFTYPE_RES_CACHE,
1476     },
1477     {
1478         .name       = "min_bandwidth",
1479         .mode       = 0444,
1480         .kf_ops     = &rdtgroup_kf_single_ops,
1481         .seq_show   = rdt_min_bw_show,
1482         .fflags     = RF_CTRL_INFO | RFTYPE_RES_MB,
1483     },
1484     {
1485         .name       = "bandwidth_gran",
1486         .mode       = 0444,
1487         .kf_ops     = &rdtgroup_kf_single_ops,
1488         .seq_show   = rdt_bw_gran_show,
1489         .fflags     = RF_CTRL_INFO | RFTYPE_RES_MB,
1490     },
1491     {
1492         .name       = "delay_linear",
1493         .mode       = 0444,
1494         .kf_ops     = &rdtgroup_kf_single_ops,
1495         .seq_show   = rdt_delay_linear_show,
1496         .fflags     = RF_CTRL_INFO | RFTYPE_RES_MB,
1497     },
1498     /*
1499      * Platform specific which (if any) capabilities are provided by
1500      * thread_throttle_mode. Defer "fflags" initialization to platform
1501      * discovery.
1502      */
1503     {
1504         .name       = "thread_throttle_mode",
1505         .mode       = 0444,
1506         .kf_ops     = &rdtgroup_kf_single_ops,
1507         .seq_show   = rdt_thread_throttle_mode_show,
1508     },
1509     {
1510         .name       = "max_threshold_occupancy",
1511         .mode       = 0644,
1512         .kf_ops     = &rdtgroup_kf_single_ops,
1513         .write      = max_threshold_occ_write,
1514         .seq_show   = max_threshold_occ_show,
1515         .fflags     = RF_MON_INFO | RFTYPE_RES_CACHE,
1516     },
1517     {
1518         .name       = "cpus",
1519         .mode       = 0644,
1520         .kf_ops     = &rdtgroup_kf_single_ops,
1521         .write      = rdtgroup_cpus_write,
1522         .seq_show   = rdtgroup_cpus_show,
1523         .fflags     = RFTYPE_BASE,
1524     },
1525     {
1526         .name       = "cpus_list",
1527         .mode       = 0644,
1528         .kf_ops     = &rdtgroup_kf_single_ops,
1529         .write      = rdtgroup_cpus_write,
1530         .seq_show   = rdtgroup_cpus_show,
1531         .flags      = RFTYPE_FLAGS_CPUS_LIST,
1532         .fflags     = RFTYPE_BASE,
1533     },
1534     {
1535         .name       = "tasks",
1536         .mode       = 0644,
1537         .kf_ops     = &rdtgroup_kf_single_ops,
1538         .write      = rdtgroup_tasks_write,
1539         .seq_show   = rdtgroup_tasks_show,
1540         .fflags     = RFTYPE_BASE,
1541     },
1542     {
1543         .name       = "schemata",
1544         .mode       = 0644,
1545         .kf_ops     = &rdtgroup_kf_single_ops,
1546         .write      = rdtgroup_schemata_write,
1547         .seq_show   = rdtgroup_schemata_show,
1548         .fflags     = RF_CTRL_BASE,
1549     },
1550     {
1551         .name       = "mode",
1552         .mode       = 0644,
1553         .kf_ops     = &rdtgroup_kf_single_ops,
1554         .write      = rdtgroup_mode_write,
1555         .seq_show   = rdtgroup_mode_show,
1556         .fflags     = RF_CTRL_BASE,
1557     },
1558     {
1559         .name       = "size",
1560         .mode       = 0444,
1561         .kf_ops     = &rdtgroup_kf_single_ops,
1562         .seq_show   = rdtgroup_size_show,
1563         .fflags     = RF_CTRL_BASE,
1564     },
1565 
1566 };
1567 
1568 static int rdtgroup_add_files(struct kernfs_node *kn, unsigned long fflags)
1569 {
1570     struct rftype *rfts, *rft;
1571     int ret, len;
1572 
1573     rfts = res_common_files;
1574     len = ARRAY_SIZE(res_common_files);
1575 
1576     lockdep_assert_held(&rdtgroup_mutex);
1577 
1578     for (rft = rfts; rft < rfts + len; rft++) {
1579         if (rft->fflags && ((fflags & rft->fflags) == rft->fflags)) {
1580             ret = rdtgroup_add_file(kn, rft);
1581             if (ret)
1582                 goto error;
1583         }
1584     }
1585 
1586     return 0;
1587 error:
1588     pr_warn("Failed to add %s, err=%d\n", rft->name, ret);
1589     while (--rft >= rfts) {
1590         if ((fflags & rft->fflags) == rft->fflags)
1591             kernfs_remove_by_name(kn, rft->name);
1592     }
1593     return ret;
1594 }
1595 
1596 static struct rftype *rdtgroup_get_rftype_by_name(const char *name)
1597 {
1598     struct rftype *rfts, *rft;
1599     int len;
1600 
1601     rfts = res_common_files;
1602     len = ARRAY_SIZE(res_common_files);
1603 
1604     for (rft = rfts; rft < rfts + len; rft++) {
1605         if (!strcmp(rft->name, name))
1606             return rft;
1607     }
1608 
1609     return NULL;
1610 }
1611 
1612 void __init thread_throttle_mode_init(void)
1613 {
1614     struct rftype *rft;
1615 
1616     rft = rdtgroup_get_rftype_by_name("thread_throttle_mode");
1617     if (!rft)
1618         return;
1619 
1620     rft->fflags = RF_CTRL_INFO | RFTYPE_RES_MB;
1621 }
1622 
1623 /**
1624  * rdtgroup_kn_mode_restrict - Restrict user access to named resctrl file
1625  * @r: The resource group with which the file is associated.
1626  * @name: Name of the file
1627  *
1628  * The permissions of named resctrl file, directory, or link are modified
1629  * to not allow read, write, or execute by any user.
1630  *
1631  * WARNING: This function is intended to communicate to the user that the
1632  * resctrl file has been locked down - that it is not relevant to the
1633  * particular state the system finds itself in. It should not be relied
1634  * on to protect from user access because after the file's permissions
1635  * are restricted the user can still change the permissions using chmod
1636  * from the command line.
1637  *
1638  * Return: 0 on success, <0 on failure.
1639  */
1640 int rdtgroup_kn_mode_restrict(struct rdtgroup *r, const char *name)
1641 {
1642     struct iattr iattr = {.ia_valid = ATTR_MODE,};
1643     struct kernfs_node *kn;
1644     int ret = 0;
1645 
1646     kn = kernfs_find_and_get_ns(r->kn, name, NULL);
1647     if (!kn)
1648         return -ENOENT;
1649 
1650     switch (kernfs_type(kn)) {
1651     case KERNFS_DIR:
1652         iattr.ia_mode = S_IFDIR;
1653         break;
1654     case KERNFS_FILE:
1655         iattr.ia_mode = S_IFREG;
1656         break;
1657     case KERNFS_LINK:
1658         iattr.ia_mode = S_IFLNK;
1659         break;
1660     }
1661 
1662     ret = kernfs_setattr(kn, &iattr);
1663     kernfs_put(kn);
1664     return ret;
1665 }
1666 
1667 /**
1668  * rdtgroup_kn_mode_restore - Restore user access to named resctrl file
1669  * @r: The resource group with which the file is associated.
1670  * @name: Name of the file
1671  * @mask: Mask of permissions that should be restored
1672  *
1673  * Restore the permissions of the named file. If @name is a directory the
1674  * permissions of its parent will be used.
1675  *
1676  * Return: 0 on success, <0 on failure.
1677  */
1678 int rdtgroup_kn_mode_restore(struct rdtgroup *r, const char *name,
1679                  umode_t mask)
1680 {
1681     struct iattr iattr = {.ia_valid = ATTR_MODE,};
1682     struct kernfs_node *kn, *parent;
1683     struct rftype *rfts, *rft;
1684     int ret, len;
1685 
1686     rfts = res_common_files;
1687     len = ARRAY_SIZE(res_common_files);
1688 
1689     for (rft = rfts; rft < rfts + len; rft++) {
1690         if (!strcmp(rft->name, name))
1691             iattr.ia_mode = rft->mode & mask;
1692     }
1693 
1694     kn = kernfs_find_and_get_ns(r->kn, name, NULL);
1695     if (!kn)
1696         return -ENOENT;
1697 
1698     switch (kernfs_type(kn)) {
1699     case KERNFS_DIR:
1700         parent = kernfs_get_parent(kn);
1701         if (parent) {
1702             iattr.ia_mode |= parent->mode;
1703             kernfs_put(parent);
1704         }
1705         iattr.ia_mode |= S_IFDIR;
1706         break;
1707     case KERNFS_FILE:
1708         iattr.ia_mode |= S_IFREG;
1709         break;
1710     case KERNFS_LINK:
1711         iattr.ia_mode |= S_IFLNK;
1712         break;
1713     }
1714 
1715     ret = kernfs_setattr(kn, &iattr);
1716     kernfs_put(kn);
1717     return ret;
1718 }
1719 
1720 static int rdtgroup_mkdir_info_resdir(void *priv, char *name,
1721                       unsigned long fflags)
1722 {
1723     struct kernfs_node *kn_subdir;
1724     int ret;
1725 
1726     kn_subdir = kernfs_create_dir(kn_info, name,
1727                       kn_info->mode, priv);
1728     if (IS_ERR(kn_subdir))
1729         return PTR_ERR(kn_subdir);
1730 
1731     ret = rdtgroup_kn_set_ugid(kn_subdir);
1732     if (ret)
1733         return ret;
1734 
1735     ret = rdtgroup_add_files(kn_subdir, fflags);
1736     if (!ret)
1737         kernfs_activate(kn_subdir);
1738 
1739     return ret;
1740 }
1741 
1742 static int rdtgroup_create_info_dir(struct kernfs_node *parent_kn)
1743 {
1744     struct resctrl_schema *s;
1745     struct rdt_resource *r;
1746     unsigned long fflags;
1747     char name[32];
1748     int ret;
1749 
1750     /* create the directory */
1751     kn_info = kernfs_create_dir(parent_kn, "info", parent_kn->mode, NULL);
1752     if (IS_ERR(kn_info))
1753         return PTR_ERR(kn_info);
1754 
1755     ret = rdtgroup_add_files(kn_info, RF_TOP_INFO);
1756     if (ret)
1757         goto out_destroy;
1758 
1759     /* loop over enabled controls, these are all alloc_enabled */
1760     list_for_each_entry(s, &resctrl_schema_all, list) {
1761         r = s->res;
1762         fflags =  r->fflags | RF_CTRL_INFO;
1763         ret = rdtgroup_mkdir_info_resdir(s, s->name, fflags);
1764         if (ret)
1765             goto out_destroy;
1766     }
1767 
1768     for_each_mon_enabled_rdt_resource(r) {
1769         fflags =  r->fflags | RF_MON_INFO;
1770         sprintf(name, "%s_MON", r->name);
1771         ret = rdtgroup_mkdir_info_resdir(r, name, fflags);
1772         if (ret)
1773             goto out_destroy;
1774     }
1775 
1776     ret = rdtgroup_kn_set_ugid(kn_info);
1777     if (ret)
1778         goto out_destroy;
1779 
1780     kernfs_activate(kn_info);
1781 
1782     return 0;
1783 
1784 out_destroy:
1785     kernfs_remove(kn_info);
1786     return ret;
1787 }
1788 
1789 static int
1790 mongroup_create_dir(struct kernfs_node *parent_kn, struct rdtgroup *prgrp,
1791             char *name, struct kernfs_node **dest_kn)
1792 {
1793     struct kernfs_node *kn;
1794     int ret;
1795 
1796     /* create the directory */
1797     kn = kernfs_create_dir(parent_kn, name, parent_kn->mode, prgrp);
1798     if (IS_ERR(kn))
1799         return PTR_ERR(kn);
1800 
1801     if (dest_kn)
1802         *dest_kn = kn;
1803 
1804     ret = rdtgroup_kn_set_ugid(kn);
1805     if (ret)
1806         goto out_destroy;
1807 
1808     kernfs_activate(kn);
1809 
1810     return 0;
1811 
1812 out_destroy:
1813     kernfs_remove(kn);
1814     return ret;
1815 }
1816 
1817 static void l3_qos_cfg_update(void *arg)
1818 {
1819     bool *enable = arg;
1820 
1821     wrmsrl(MSR_IA32_L3_QOS_CFG, *enable ? L3_QOS_CDP_ENABLE : 0ULL);
1822 }
1823 
1824 static void l2_qos_cfg_update(void *arg)
1825 {
1826     bool *enable = arg;
1827 
1828     wrmsrl(MSR_IA32_L2_QOS_CFG, *enable ? L2_QOS_CDP_ENABLE : 0ULL);
1829 }
1830 
1831 static inline bool is_mba_linear(void)
1832 {
1833     return rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl.membw.delay_linear;
1834 }
1835 
1836 static int set_cache_qos_cfg(int level, bool enable)
1837 {
1838     void (*update)(void *arg);
1839     struct rdt_resource *r_l;
1840     cpumask_var_t cpu_mask;
1841     struct rdt_domain *d;
1842     int cpu;
1843 
1844     if (level == RDT_RESOURCE_L3)
1845         update = l3_qos_cfg_update;
1846     else if (level == RDT_RESOURCE_L2)
1847         update = l2_qos_cfg_update;
1848     else
1849         return -EINVAL;
1850 
1851     if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL))
1852         return -ENOMEM;
1853 
1854     r_l = &rdt_resources_all[level].r_resctrl;
1855     list_for_each_entry(d, &r_l->domains, list) {
1856         if (r_l->cache.arch_has_per_cpu_cfg)
1857             /* Pick all the CPUs in the domain instance */
1858             for_each_cpu(cpu, &d->cpu_mask)
1859                 cpumask_set_cpu(cpu, cpu_mask);
1860         else
1861             /* Pick one CPU from each domain instance to update MSR */
1862             cpumask_set_cpu(cpumask_any(&d->cpu_mask), cpu_mask);
1863     }
1864     cpu = get_cpu();
1865     /* Update QOS_CFG MSR on this cpu if it's in cpu_mask. */
1866     if (cpumask_test_cpu(cpu, cpu_mask))
1867         update(&enable);
1868     /* Update QOS_CFG MSR on all other cpus in cpu_mask. */
1869     smp_call_function_many(cpu_mask, update, &enable, 1);
1870     put_cpu();
1871 
1872     free_cpumask_var(cpu_mask);
1873 
1874     return 0;
1875 }
1876 
1877 /* Restore the qos cfg state when a domain comes online */
1878 void rdt_domain_reconfigure_cdp(struct rdt_resource *r)
1879 {
1880     struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
1881 
1882     if (!r->cdp_capable)
1883         return;
1884 
1885     if (r->rid == RDT_RESOURCE_L2)
1886         l2_qos_cfg_update(&hw_res->cdp_enabled);
1887 
1888     if (r->rid == RDT_RESOURCE_L3)
1889         l3_qos_cfg_update(&hw_res->cdp_enabled);
1890 }
1891 
1892 /*
1893  * Enable or disable the MBA software controller
1894  * which helps user specify bandwidth in MBps.
1895  * MBA software controller is supported only if
1896  * MBM is supported and MBA is in linear scale.
1897  */
1898 static int set_mba_sc(bool mba_sc)
1899 {
1900     struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
1901     struct rdt_hw_domain *hw_dom;
1902     struct rdt_domain *d;
1903 
1904     if (!is_mbm_enabled() || !is_mba_linear() ||
1905         mba_sc == is_mba_sc(r))
1906         return -EINVAL;
1907 
1908     r->membw.mba_sc = mba_sc;
1909     list_for_each_entry(d, &r->domains, list) {
1910         hw_dom = resctrl_to_arch_dom(d);
1911         setup_default_ctrlval(r, hw_dom->ctrl_val, hw_dom->mbps_val);
1912     }
1913 
1914     return 0;
1915 }
1916 
1917 static int cdp_enable(int level)
1918 {
1919     struct rdt_resource *r_l = &rdt_resources_all[level].r_resctrl;
1920     int ret;
1921 
1922     if (!r_l->alloc_capable)
1923         return -EINVAL;
1924 
1925     ret = set_cache_qos_cfg(level, true);
1926     if (!ret)
1927         rdt_resources_all[level].cdp_enabled = true;
1928 
1929     return ret;
1930 }
1931 
1932 static void cdp_disable(int level)
1933 {
1934     struct rdt_hw_resource *r_hw = &rdt_resources_all[level];
1935 
1936     if (r_hw->cdp_enabled) {
1937         set_cache_qos_cfg(level, false);
1938         r_hw->cdp_enabled = false;
1939     }
1940 }
1941 
1942 int resctrl_arch_set_cdp_enabled(enum resctrl_res_level l, bool enable)
1943 {
1944     struct rdt_hw_resource *hw_res = &rdt_resources_all[l];
1945 
1946     if (!hw_res->r_resctrl.cdp_capable)
1947         return -EINVAL;
1948 
1949     if (enable)
1950         return cdp_enable(l);
1951 
1952     cdp_disable(l);
1953 
1954     return 0;
1955 }
1956 
1957 static void cdp_disable_all(void)
1958 {
1959     if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L3))
1960         resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, false);
1961     if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L2))
1962         resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, false);
1963 }
1964 
1965 /*
1966  * We don't allow rdtgroup directories to be created anywhere
1967  * except the root directory. Thus when looking for the rdtgroup
1968  * structure for a kernfs node we are either looking at a directory,
1969  * in which case the rdtgroup structure is pointed at by the "priv"
1970  * field, otherwise we have a file, and need only look to the parent
1971  * to find the rdtgroup.
1972  */
1973 static struct rdtgroup *kernfs_to_rdtgroup(struct kernfs_node *kn)
1974 {
1975     if (kernfs_type(kn) == KERNFS_DIR) {
1976         /*
1977          * All the resource directories use "kn->priv"
1978          * to point to the "struct rdtgroup" for the
1979          * resource. "info" and its subdirectories don't
1980          * have rdtgroup structures, so return NULL here.
1981          */
1982         if (kn == kn_info || kn->parent == kn_info)
1983             return NULL;
1984         else
1985             return kn->priv;
1986     } else {
1987         return kn->parent->priv;
1988     }
1989 }
1990 
1991 struct rdtgroup *rdtgroup_kn_lock_live(struct kernfs_node *kn)
1992 {
1993     struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn);
1994 
1995     if (!rdtgrp)
1996         return NULL;
1997 
1998     atomic_inc(&rdtgrp->waitcount);
1999     kernfs_break_active_protection(kn);
2000 
2001     mutex_lock(&rdtgroup_mutex);
2002 
2003     /* Was this group deleted while we waited? */
2004     if (rdtgrp->flags & RDT_DELETED)
2005         return NULL;
2006 
2007     return rdtgrp;
2008 }
2009 
2010 void rdtgroup_kn_unlock(struct kernfs_node *kn)
2011 {
2012     struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn);
2013 
2014     if (!rdtgrp)
2015         return;
2016 
2017     mutex_unlock(&rdtgroup_mutex);
2018 
2019     if (atomic_dec_and_test(&rdtgrp->waitcount) &&
2020         (rdtgrp->flags & RDT_DELETED)) {
2021         if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
2022             rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED)
2023             rdtgroup_pseudo_lock_remove(rdtgrp);
2024         kernfs_unbreak_active_protection(kn);
2025         rdtgroup_remove(rdtgrp);
2026     } else {
2027         kernfs_unbreak_active_protection(kn);
2028     }
2029 }
2030 
2031 static int mkdir_mondata_all(struct kernfs_node *parent_kn,
2032                  struct rdtgroup *prgrp,
2033                  struct kernfs_node **mon_data_kn);
2034 
2035 static int rdt_enable_ctx(struct rdt_fs_context *ctx)
2036 {
2037     int ret = 0;
2038 
2039     if (ctx->enable_cdpl2)
2040         ret = resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, true);
2041 
2042     if (!ret && ctx->enable_cdpl3)
2043         ret = resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, true);
2044 
2045     if (!ret && ctx->enable_mba_mbps)
2046         ret = set_mba_sc(true);
2047 
2048     return ret;
2049 }
2050 
2051 static int schemata_list_add(struct rdt_resource *r, enum resctrl_conf_type type)
2052 {
2053     struct resctrl_schema *s;
2054     const char *suffix = "";
2055     int ret, cl;
2056 
2057     s = kzalloc(sizeof(*s), GFP_KERNEL);
2058     if (!s)
2059         return -ENOMEM;
2060 
2061     s->res = r;
2062     s->num_closid = resctrl_arch_get_num_closid(r);
2063     if (resctrl_arch_get_cdp_enabled(r->rid))
2064         s->num_closid /= 2;
2065 
2066     s->conf_type = type;
2067     switch (type) {
2068     case CDP_CODE:
2069         suffix = "CODE";
2070         break;
2071     case CDP_DATA:
2072         suffix = "DATA";
2073         break;
2074     case CDP_NONE:
2075         suffix = "";
2076         break;
2077     }
2078 
2079     ret = snprintf(s->name, sizeof(s->name), "%s%s", r->name, suffix);
2080     if (ret >= sizeof(s->name)) {
2081         kfree(s);
2082         return -EINVAL;
2083     }
2084 
2085     cl = strlen(s->name);
2086 
2087     /*
2088      * If CDP is supported by this resource, but not enabled,
2089      * include the suffix. This ensures the tabular format of the
2090      * schemata file does not change between mounts of the filesystem.
2091      */
2092     if (r->cdp_capable && !resctrl_arch_get_cdp_enabled(r->rid))
2093         cl += 4;
2094 
2095     if (cl > max_name_width)
2096         max_name_width = cl;
2097 
2098     INIT_LIST_HEAD(&s->list);
2099     list_add(&s->list, &resctrl_schema_all);
2100 
2101     return 0;
2102 }
2103 
2104 static int schemata_list_create(void)
2105 {
2106     struct rdt_resource *r;
2107     int ret = 0;
2108 
2109     for_each_alloc_enabled_rdt_resource(r) {
2110         if (resctrl_arch_get_cdp_enabled(r->rid)) {
2111             ret = schemata_list_add(r, CDP_CODE);
2112             if (ret)
2113                 break;
2114 
2115             ret = schemata_list_add(r, CDP_DATA);
2116         } else {
2117             ret = schemata_list_add(r, CDP_NONE);
2118         }
2119 
2120         if (ret)
2121             break;
2122     }
2123 
2124     return ret;
2125 }
2126 
2127 static void schemata_list_destroy(void)
2128 {
2129     struct resctrl_schema *s, *tmp;
2130 
2131     list_for_each_entry_safe(s, tmp, &resctrl_schema_all, list) {
2132         list_del(&s->list);
2133         kfree(s);
2134     }
2135 }
2136 
2137 static int rdt_get_tree(struct fs_context *fc)
2138 {
2139     struct rdt_fs_context *ctx = rdt_fc2context(fc);
2140     struct rdt_domain *dom;
2141     struct rdt_resource *r;
2142     int ret;
2143 
2144     cpus_read_lock();
2145     mutex_lock(&rdtgroup_mutex);
2146     /*
2147      * resctrl file system can only be mounted once.
2148      */
2149     if (static_branch_unlikely(&rdt_enable_key)) {
2150         ret = -EBUSY;
2151         goto out;
2152     }
2153 
2154     ret = rdt_enable_ctx(ctx);
2155     if (ret < 0)
2156         goto out_cdp;
2157 
2158     ret = schemata_list_create();
2159     if (ret) {
2160         schemata_list_destroy();
2161         goto out_mba;
2162     }
2163 
2164     closid_init();
2165 
2166     ret = rdtgroup_create_info_dir(rdtgroup_default.kn);
2167     if (ret < 0)
2168         goto out_schemata_free;
2169 
2170     if (rdt_mon_capable) {
2171         ret = mongroup_create_dir(rdtgroup_default.kn,
2172                       &rdtgroup_default, "mon_groups",
2173                       &kn_mongrp);
2174         if (ret < 0)
2175             goto out_info;
2176 
2177         ret = mkdir_mondata_all(rdtgroup_default.kn,
2178                     &rdtgroup_default, &kn_mondata);
2179         if (ret < 0)
2180             goto out_mongrp;
2181         rdtgroup_default.mon.mon_data_kn = kn_mondata;
2182     }
2183 
2184     ret = rdt_pseudo_lock_init();
2185     if (ret)
2186         goto out_mondata;
2187 
2188     ret = kernfs_get_tree(fc);
2189     if (ret < 0)
2190         goto out_psl;
2191 
2192     if (rdt_alloc_capable)
2193         static_branch_enable_cpuslocked(&rdt_alloc_enable_key);
2194     if (rdt_mon_capable)
2195         static_branch_enable_cpuslocked(&rdt_mon_enable_key);
2196 
2197     if (rdt_alloc_capable || rdt_mon_capable)
2198         static_branch_enable_cpuslocked(&rdt_enable_key);
2199 
2200     if (is_mbm_enabled()) {
2201         r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
2202         list_for_each_entry(dom, &r->domains, list)
2203             mbm_setup_overflow_handler(dom, MBM_OVERFLOW_INTERVAL);
2204     }
2205 
2206     goto out;
2207 
2208 out_psl:
2209     rdt_pseudo_lock_release();
2210 out_mondata:
2211     if (rdt_mon_capable)
2212         kernfs_remove(kn_mondata);
2213 out_mongrp:
2214     if (rdt_mon_capable)
2215         kernfs_remove(kn_mongrp);
2216 out_info:
2217     kernfs_remove(kn_info);
2218 out_schemata_free:
2219     schemata_list_destroy();
2220 out_mba:
2221     if (ctx->enable_mba_mbps)
2222         set_mba_sc(false);
2223 out_cdp:
2224     cdp_disable_all();
2225 out:
2226     rdt_last_cmd_clear();
2227     mutex_unlock(&rdtgroup_mutex);
2228     cpus_read_unlock();
2229     return ret;
2230 }
2231 
2232 enum rdt_param {
2233     Opt_cdp,
2234     Opt_cdpl2,
2235     Opt_mba_mbps,
2236     nr__rdt_params
2237 };
2238 
2239 static const struct fs_parameter_spec rdt_fs_parameters[] = {
2240     fsparam_flag("cdp",     Opt_cdp),
2241     fsparam_flag("cdpl2",       Opt_cdpl2),
2242     fsparam_flag("mba_MBps",    Opt_mba_mbps),
2243     {}
2244 };
2245 
2246 static int rdt_parse_param(struct fs_context *fc, struct fs_parameter *param)
2247 {
2248     struct rdt_fs_context *ctx = rdt_fc2context(fc);
2249     struct fs_parse_result result;
2250     int opt;
2251 
2252     opt = fs_parse(fc, rdt_fs_parameters, param, &result);
2253     if (opt < 0)
2254         return opt;
2255 
2256     switch (opt) {
2257     case Opt_cdp:
2258         ctx->enable_cdpl3 = true;
2259         return 0;
2260     case Opt_cdpl2:
2261         ctx->enable_cdpl2 = true;
2262         return 0;
2263     case Opt_mba_mbps:
2264         if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
2265             return -EINVAL;
2266         ctx->enable_mba_mbps = true;
2267         return 0;
2268     }
2269 
2270     return -EINVAL;
2271 }
2272 
2273 static void rdt_fs_context_free(struct fs_context *fc)
2274 {
2275     struct rdt_fs_context *ctx = rdt_fc2context(fc);
2276 
2277     kernfs_free_fs_context(fc);
2278     kfree(ctx);
2279 }
2280 
2281 static const struct fs_context_operations rdt_fs_context_ops = {
2282     .free       = rdt_fs_context_free,
2283     .parse_param    = rdt_parse_param,
2284     .get_tree   = rdt_get_tree,
2285 };
2286 
2287 static int rdt_init_fs_context(struct fs_context *fc)
2288 {
2289     struct rdt_fs_context *ctx;
2290 
2291     ctx = kzalloc(sizeof(struct rdt_fs_context), GFP_KERNEL);
2292     if (!ctx)
2293         return -ENOMEM;
2294 
2295     ctx->kfc.root = rdt_root;
2296     ctx->kfc.magic = RDTGROUP_SUPER_MAGIC;
2297     fc->fs_private = &ctx->kfc;
2298     fc->ops = &rdt_fs_context_ops;
2299     put_user_ns(fc->user_ns);
2300     fc->user_ns = get_user_ns(&init_user_ns);
2301     fc->global = true;
2302     return 0;
2303 }
2304 
2305 static int reset_all_ctrls(struct rdt_resource *r)
2306 {
2307     struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
2308     struct rdt_hw_domain *hw_dom;
2309     struct msr_param msr_param;
2310     cpumask_var_t cpu_mask;
2311     struct rdt_domain *d;
2312     int i, cpu;
2313 
2314     if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL))
2315         return -ENOMEM;
2316 
2317     msr_param.res = r;
2318     msr_param.low = 0;
2319     msr_param.high = hw_res->num_closid;
2320 
2321     /*
2322      * Disable resource control for this resource by setting all
2323      * CBMs in all domains to the maximum mask value. Pick one CPU
2324      * from each domain to update the MSRs below.
2325      */
2326     list_for_each_entry(d, &r->domains, list) {
2327         hw_dom = resctrl_to_arch_dom(d);
2328         cpumask_set_cpu(cpumask_any(&d->cpu_mask), cpu_mask);
2329 
2330         for (i = 0; i < hw_res->num_closid; i++)
2331             hw_dom->ctrl_val[i] = r->default_ctrl;
2332     }
2333     cpu = get_cpu();
2334     /* Update CBM on this cpu if it's in cpu_mask. */
2335     if (cpumask_test_cpu(cpu, cpu_mask))
2336         rdt_ctrl_update(&msr_param);
2337     /* Update CBM on all other cpus in cpu_mask. */
2338     smp_call_function_many(cpu_mask, rdt_ctrl_update, &msr_param, 1);
2339     put_cpu();
2340 
2341     free_cpumask_var(cpu_mask);
2342 
2343     return 0;
2344 }
2345 
2346 /*
2347  * Move tasks from one to the other group. If @from is NULL, then all tasks
2348  * in the systems are moved unconditionally (used for teardown).
2349  *
2350  * If @mask is not NULL the cpus on which moved tasks are running are set
2351  * in that mask so the update smp function call is restricted to affected
2352  * cpus.
2353  */
2354 static void rdt_move_group_tasks(struct rdtgroup *from, struct rdtgroup *to,
2355                  struct cpumask *mask)
2356 {
2357     struct task_struct *p, *t;
2358 
2359     read_lock(&tasklist_lock);
2360     for_each_process_thread(p, t) {
2361         if (!from || is_closid_match(t, from) ||
2362             is_rmid_match(t, from)) {
2363             WRITE_ONCE(t->closid, to->closid);
2364             WRITE_ONCE(t->rmid, to->mon.rmid);
2365 
2366             /*
2367              * If the task is on a CPU, set the CPU in the mask.
2368              * The detection is inaccurate as tasks might move or
2369              * schedule before the smp function call takes place.
2370              * In such a case the function call is pointless, but
2371              * there is no other side effect.
2372              */
2373             if (IS_ENABLED(CONFIG_SMP) && mask && task_curr(t))
2374                 cpumask_set_cpu(task_cpu(t), mask);
2375         }
2376     }
2377     read_unlock(&tasklist_lock);
2378 }
2379 
2380 static void free_all_child_rdtgrp(struct rdtgroup *rdtgrp)
2381 {
2382     struct rdtgroup *sentry, *stmp;
2383     struct list_head *head;
2384 
2385     head = &rdtgrp->mon.crdtgrp_list;
2386     list_for_each_entry_safe(sentry, stmp, head, mon.crdtgrp_list) {
2387         free_rmid(sentry->mon.rmid);
2388         list_del(&sentry->mon.crdtgrp_list);
2389 
2390         if (atomic_read(&sentry->waitcount) != 0)
2391             sentry->flags = RDT_DELETED;
2392         else
2393             rdtgroup_remove(sentry);
2394     }
2395 }
2396 
2397 /*
2398  * Forcibly remove all of subdirectories under root.
2399  */
2400 static void rmdir_all_sub(void)
2401 {
2402     struct rdtgroup *rdtgrp, *tmp;
2403 
2404     /* Move all tasks to the default resource group */
2405     rdt_move_group_tasks(NULL, &rdtgroup_default, NULL);
2406 
2407     list_for_each_entry_safe(rdtgrp, tmp, &rdt_all_groups, rdtgroup_list) {
2408         /* Free any child rmids */
2409         free_all_child_rdtgrp(rdtgrp);
2410 
2411         /* Remove each rdtgroup other than root */
2412         if (rdtgrp == &rdtgroup_default)
2413             continue;
2414 
2415         if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
2416             rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED)
2417             rdtgroup_pseudo_lock_remove(rdtgrp);
2418 
2419         /*
2420          * Give any CPUs back to the default group. We cannot copy
2421          * cpu_online_mask because a CPU might have executed the
2422          * offline callback already, but is still marked online.
2423          */
2424         cpumask_or(&rdtgroup_default.cpu_mask,
2425                &rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);
2426 
2427         free_rmid(rdtgrp->mon.rmid);
2428 
2429         kernfs_remove(rdtgrp->kn);
2430         list_del(&rdtgrp->rdtgroup_list);
2431 
2432         if (atomic_read(&rdtgrp->waitcount) != 0)
2433             rdtgrp->flags = RDT_DELETED;
2434         else
2435             rdtgroup_remove(rdtgrp);
2436     }
2437     /* Notify online CPUs to update per cpu storage and PQR_ASSOC MSR */
2438     update_closid_rmid(cpu_online_mask, &rdtgroup_default);
2439 
2440     kernfs_remove(kn_info);
2441     kernfs_remove(kn_mongrp);
2442     kernfs_remove(kn_mondata);
2443 }
2444 
2445 static void rdt_kill_sb(struct super_block *sb)
2446 {
2447     struct rdt_resource *r;
2448 
2449     cpus_read_lock();
2450     mutex_lock(&rdtgroup_mutex);
2451 
2452     set_mba_sc(false);
2453 
2454     /*Put everything back to default values. */
2455     for_each_alloc_enabled_rdt_resource(r)
2456         reset_all_ctrls(r);
2457     cdp_disable_all();
2458     rmdir_all_sub();
2459     rdt_pseudo_lock_release();
2460     rdtgroup_default.mode = RDT_MODE_SHAREABLE;
2461     schemata_list_destroy();
2462     static_branch_disable_cpuslocked(&rdt_alloc_enable_key);
2463     static_branch_disable_cpuslocked(&rdt_mon_enable_key);
2464     static_branch_disable_cpuslocked(&rdt_enable_key);
2465     kernfs_kill_sb(sb);
2466     mutex_unlock(&rdtgroup_mutex);
2467     cpus_read_unlock();
2468 }
2469 
2470 static struct file_system_type rdt_fs_type = {
2471     .name           = "resctrl",
2472     .init_fs_context    = rdt_init_fs_context,
2473     .parameters     = rdt_fs_parameters,
2474     .kill_sb        = rdt_kill_sb,
2475 };
2476 
2477 static int mon_addfile(struct kernfs_node *parent_kn, const char *name,
2478                void *priv)
2479 {
2480     struct kernfs_node *kn;
2481     int ret = 0;
2482 
2483     kn = __kernfs_create_file(parent_kn, name, 0444,
2484                   GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, 0,
2485                   &kf_mondata_ops, priv, NULL, NULL);
2486     if (IS_ERR(kn))
2487         return PTR_ERR(kn);
2488 
2489     ret = rdtgroup_kn_set_ugid(kn);
2490     if (ret) {
2491         kernfs_remove(kn);
2492         return ret;
2493     }
2494 
2495     return ret;
2496 }
2497 
2498 /*
2499  * Remove all subdirectories of mon_data of ctrl_mon groups
2500  * and monitor groups with given domain id.
2501  */
2502 void rmdir_mondata_subdir_allrdtgrp(struct rdt_resource *r, unsigned int dom_id)
2503 {
2504     struct rdtgroup *prgrp, *crgrp;
2505     char name[32];
2506 
2507     if (!r->mon_enabled)
2508         return;
2509 
2510     list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
2511         sprintf(name, "mon_%s_%02d", r->name, dom_id);
2512         kernfs_remove_by_name(prgrp->mon.mon_data_kn, name);
2513 
2514         list_for_each_entry(crgrp, &prgrp->mon.crdtgrp_list, mon.crdtgrp_list)
2515             kernfs_remove_by_name(crgrp->mon.mon_data_kn, name);
2516     }
2517 }
2518 
2519 static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
2520                 struct rdt_domain *d,
2521                 struct rdt_resource *r, struct rdtgroup *prgrp)
2522 {
2523     union mon_data_bits priv;
2524     struct kernfs_node *kn;
2525     struct mon_evt *mevt;
2526     struct rmid_read rr;
2527     char name[32];
2528     int ret;
2529 
2530     sprintf(name, "mon_%s_%02d", r->name, d->id);
2531     /* create the directory */
2532     kn = kernfs_create_dir(parent_kn, name, parent_kn->mode, prgrp);
2533     if (IS_ERR(kn))
2534         return PTR_ERR(kn);
2535 
2536     ret = rdtgroup_kn_set_ugid(kn);
2537     if (ret)
2538         goto out_destroy;
2539 
2540     if (WARN_ON(list_empty(&r->evt_list))) {
2541         ret = -EPERM;
2542         goto out_destroy;
2543     }
2544 
2545     priv.u.rid = r->rid;
2546     priv.u.domid = d->id;
2547     list_for_each_entry(mevt, &r->evt_list, list) {
2548         priv.u.evtid = mevt->evtid;
2549         ret = mon_addfile(kn, mevt->name, priv.priv);
2550         if (ret)
2551             goto out_destroy;
2552 
2553         if (is_mbm_event(mevt->evtid))
2554             mon_event_read(&rr, r, d, prgrp, mevt->evtid, true);
2555     }
2556     kernfs_activate(kn);
2557     return 0;
2558 
2559 out_destroy:
2560     kernfs_remove(kn);
2561     return ret;
2562 }
2563 
2564 /*
2565  * Add all subdirectories of mon_data for "ctrl_mon" groups
2566  * and "monitor" groups with given domain id.
2567  */
2568 void mkdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
2569                     struct rdt_domain *d)
2570 {
2571     struct kernfs_node *parent_kn;
2572     struct rdtgroup *prgrp, *crgrp;
2573     struct list_head *head;
2574 
2575     if (!r->mon_enabled)
2576         return;
2577 
2578     list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
2579         parent_kn = prgrp->mon.mon_data_kn;
2580         mkdir_mondata_subdir(parent_kn, d, r, prgrp);
2581 
2582         head = &prgrp->mon.crdtgrp_list;
2583         list_for_each_entry(crgrp, head, mon.crdtgrp_list) {
2584             parent_kn = crgrp->mon.mon_data_kn;
2585             mkdir_mondata_subdir(parent_kn, d, r, crgrp);
2586         }
2587     }
2588 }
2589 
2590 static int mkdir_mondata_subdir_alldom(struct kernfs_node *parent_kn,
2591                        struct rdt_resource *r,
2592                        struct rdtgroup *prgrp)
2593 {
2594     struct rdt_domain *dom;
2595     int ret;
2596 
2597     list_for_each_entry(dom, &r->domains, list) {
2598         ret = mkdir_mondata_subdir(parent_kn, dom, r, prgrp);
2599         if (ret)
2600             return ret;
2601     }
2602 
2603     return 0;
2604 }
2605 
2606 /*
2607  * This creates a directory mon_data which contains the monitored data.
2608  *
2609  * mon_data has one directory for each domain which are named
2610  * in the format mon_<domain_name>_<domain_id>. For ex: A mon_data
2611  * with L3 domain looks as below:
2612  * ./mon_data:
2613  * mon_L3_00
2614  * mon_L3_01
2615  * mon_L3_02
2616  * ...
2617  *
2618  * Each domain directory has one file per event:
2619  * ./mon_L3_00/:
2620  * llc_occupancy
2621  *
2622  */
2623 static int mkdir_mondata_all(struct kernfs_node *parent_kn,
2624                  struct rdtgroup *prgrp,
2625                  struct kernfs_node **dest_kn)
2626 {
2627     struct rdt_resource *r;
2628     struct kernfs_node *kn;
2629     int ret;
2630 
2631     /*
2632      * Create the mon_data directory first.
2633      */
2634     ret = mongroup_create_dir(parent_kn, prgrp, "mon_data", &kn);
2635     if (ret)
2636         return ret;
2637 
2638     if (dest_kn)
2639         *dest_kn = kn;
2640 
2641     /*
2642      * Create the subdirectories for each domain. Note that all events
2643      * in a domain like L3 are grouped into a resource whose domain is L3
2644      */
2645     for_each_mon_enabled_rdt_resource(r) {
2646         ret = mkdir_mondata_subdir_alldom(kn, r, prgrp);
2647         if (ret)
2648             goto out_destroy;
2649     }
2650 
2651     return 0;
2652 
2653 out_destroy:
2654     kernfs_remove(kn);
2655     return ret;
2656 }
2657 
2658 /**
2659  * cbm_ensure_valid - Enforce validity on provided CBM
2660  * @_val:   Candidate CBM
2661  * @r:      RDT resource to which the CBM belongs
2662  *
2663  * The provided CBM represents all cache portions available for use. This
2664  * may be represented by a bitmap that does not consist of contiguous ones
2665  * and thus be an invalid CBM.
2666  * Here the provided CBM is forced to be a valid CBM by only considering
2667  * the first set of contiguous bits as valid and clearing all bits.
2668  * The intention here is to provide a valid default CBM with which a new
2669  * resource group is initialized. The user can follow this with a
2670  * modification to the CBM if the default does not satisfy the
2671  * requirements.
2672  */
2673 static u32 cbm_ensure_valid(u32 _val, struct rdt_resource *r)
2674 {
2675     unsigned int cbm_len = r->cache.cbm_len;
2676     unsigned long first_bit, zero_bit;
2677     unsigned long val = _val;
2678 
2679     if (!val)
2680         return 0;
2681 
2682     first_bit = find_first_bit(&val, cbm_len);
2683     zero_bit = find_next_zero_bit(&val, cbm_len, first_bit);
2684 
2685     /* Clear any remaining bits to ensure contiguous region */
2686     bitmap_clear(&val, zero_bit, cbm_len - zero_bit);
2687     return (u32)val;
2688 }
2689 
2690 /*
2691  * Initialize cache resources per RDT domain
2692  *
2693  * Set the RDT domain up to start off with all usable allocations. That is,
2694  * all shareable and unused bits. All-zero CBM is invalid.
2695  */
2696 static int __init_one_rdt_domain(struct rdt_domain *d, struct resctrl_schema *s,
2697                  u32 closid)
2698 {
2699     enum resctrl_conf_type peer_type = resctrl_peer_type(s->conf_type);
2700     enum resctrl_conf_type t = s->conf_type;
2701     struct resctrl_staged_config *cfg;
2702     struct rdt_resource *r = s->res;
2703     u32 used_b = 0, unused_b = 0;
2704     unsigned long tmp_cbm;
2705     enum rdtgrp_mode mode;
2706     u32 peer_ctl, ctrl_val;
2707     int i;
2708 
2709     cfg = &d->staged_config[t];
2710     cfg->have_new_ctrl = false;
2711     cfg->new_ctrl = r->cache.shareable_bits;
2712     used_b = r->cache.shareable_bits;
2713     for (i = 0; i < closids_supported(); i++) {
2714         if (closid_allocated(i) && i != closid) {
2715             mode = rdtgroup_mode_by_closid(i);
2716             if (mode == RDT_MODE_PSEUDO_LOCKSETUP)
2717                 /*
2718                  * ctrl values for locksetup aren't relevant
2719                  * until the schemata is written, and the mode
2720                  * becomes RDT_MODE_PSEUDO_LOCKED.
2721                  */
2722                 continue;
2723             /*
2724              * If CDP is active include peer domain's
2725              * usage to ensure there is no overlap
2726              * with an exclusive group.
2727              */
2728             if (resctrl_arch_get_cdp_enabled(r->rid))
2729                 peer_ctl = resctrl_arch_get_config(r, d, i,
2730                                    peer_type);
2731             else
2732                 peer_ctl = 0;
2733             ctrl_val = resctrl_arch_get_config(r, d, i,
2734                                s->conf_type);
2735             used_b |= ctrl_val | peer_ctl;
2736             if (mode == RDT_MODE_SHAREABLE)
2737                 cfg->new_ctrl |= ctrl_val | peer_ctl;
2738         }
2739     }
2740     if (d->plr && d->plr->cbm > 0)
2741         used_b |= d->plr->cbm;
2742     unused_b = used_b ^ (BIT_MASK(r->cache.cbm_len) - 1);
2743     unused_b &= BIT_MASK(r->cache.cbm_len) - 1;
2744     cfg->new_ctrl |= unused_b;
2745     /*
2746      * Force the initial CBM to be valid, user can
2747      * modify the CBM based on system availability.
2748      */
2749     cfg->new_ctrl = cbm_ensure_valid(cfg->new_ctrl, r);
2750     /*
2751      * Assign the u32 CBM to an unsigned long to ensure that
2752      * bitmap_weight() does not access out-of-bound memory.
2753      */
2754     tmp_cbm = cfg->new_ctrl;
2755     if (bitmap_weight(&tmp_cbm, r->cache.cbm_len) < r->cache.min_cbm_bits) {
2756         rdt_last_cmd_printf("No space on %s:%d\n", s->name, d->id);
2757         return -ENOSPC;
2758     }
2759     cfg->have_new_ctrl = true;
2760 
2761     return 0;
2762 }
2763 
2764 /*
2765  * Initialize cache resources with default values.
2766  *
2767  * A new RDT group is being created on an allocation capable (CAT)
2768  * supporting system. Set this group up to start off with all usable
2769  * allocations.
2770  *
2771  * If there are no more shareable bits available on any domain then
2772  * the entire allocation will fail.
2773  */
2774 static int rdtgroup_init_cat(struct resctrl_schema *s, u32 closid)
2775 {
2776     struct rdt_domain *d;
2777     int ret;
2778 
2779     list_for_each_entry(d, &s->res->domains, list) {
2780         ret = __init_one_rdt_domain(d, s, closid);
2781         if (ret < 0)
2782             return ret;
2783     }
2784 
2785     return 0;
2786 }
2787 
2788 /* Initialize MBA resource with default values. */
2789 static void rdtgroup_init_mba(struct rdt_resource *r)
2790 {
2791     struct resctrl_staged_config *cfg;
2792     struct rdt_domain *d;
2793 
2794     list_for_each_entry(d, &r->domains, list) {
2795         cfg = &d->staged_config[CDP_NONE];
2796         cfg->new_ctrl = is_mba_sc(r) ? MBA_MAX_MBPS : r->default_ctrl;
2797         cfg->have_new_ctrl = true;
2798     }
2799 }
2800 
2801 /* Initialize the RDT group's allocations. */
2802 static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
2803 {
2804     struct resctrl_schema *s;
2805     struct rdt_resource *r;
2806     int ret;
2807 
2808     list_for_each_entry(s, &resctrl_schema_all, list) {
2809         r = s->res;
2810         if (r->rid == RDT_RESOURCE_MBA) {
2811             rdtgroup_init_mba(r);
2812         } else {
2813             ret = rdtgroup_init_cat(s, rdtgrp->closid);
2814             if (ret < 0)
2815                 return ret;
2816         }
2817 
2818         ret = resctrl_arch_update_domains(r, rdtgrp->closid);
2819         if (ret < 0) {
2820             rdt_last_cmd_puts("Failed to initialize allocations\n");
2821             return ret;
2822         }
2823 
2824     }
2825 
2826     rdtgrp->mode = RDT_MODE_SHAREABLE;
2827 
2828     return 0;
2829 }
2830 
2831 static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
2832                  const char *name, umode_t mode,
2833                  enum rdt_group_type rtype, struct rdtgroup **r)
2834 {
2835     struct rdtgroup *prdtgrp, *rdtgrp;
2836     struct kernfs_node *kn;
2837     uint files = 0;
2838     int ret;
2839 
2840     prdtgrp = rdtgroup_kn_lock_live(parent_kn);
2841     if (!prdtgrp) {
2842         ret = -ENODEV;
2843         goto out_unlock;
2844     }
2845 
2846     if (rtype == RDTMON_GROUP &&
2847         (prdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
2848          prdtgrp->mode == RDT_MODE_PSEUDO_LOCKED)) {
2849         ret = -EINVAL;
2850         rdt_last_cmd_puts("Pseudo-locking in progress\n");
2851         goto out_unlock;
2852     }
2853 
2854     /* allocate the rdtgroup. */
2855     rdtgrp = kzalloc(sizeof(*rdtgrp), GFP_KERNEL);
2856     if (!rdtgrp) {
2857         ret = -ENOSPC;
2858         rdt_last_cmd_puts("Kernel out of memory\n");
2859         goto out_unlock;
2860     }
2861     *r = rdtgrp;
2862     rdtgrp->mon.parent = prdtgrp;
2863     rdtgrp->type = rtype;
2864     INIT_LIST_HEAD(&rdtgrp->mon.crdtgrp_list);
2865 
2866     /* kernfs creates the directory for rdtgrp */
2867     kn = kernfs_create_dir(parent_kn, name, mode, rdtgrp);
2868     if (IS_ERR(kn)) {
2869         ret = PTR_ERR(kn);
2870         rdt_last_cmd_puts("kernfs create error\n");
2871         goto out_free_rgrp;
2872     }
2873     rdtgrp->kn = kn;
2874 
2875     /*
2876      * kernfs_remove() will drop the reference count on "kn" which
2877      * will free it. But we still need it to stick around for the
2878      * rdtgroup_kn_unlock(kn) call. Take one extra reference here,
2879      * which will be dropped by kernfs_put() in rdtgroup_remove().
2880      */
2881     kernfs_get(kn);
2882 
2883     ret = rdtgroup_kn_set_ugid(kn);
2884     if (ret) {
2885         rdt_last_cmd_puts("kernfs perm error\n");
2886         goto out_destroy;
2887     }
2888 
2889     files = RFTYPE_BASE | BIT(RF_CTRLSHIFT + rtype);
2890     ret = rdtgroup_add_files(kn, files);
2891     if (ret) {
2892         rdt_last_cmd_puts("kernfs fill error\n");
2893         goto out_destroy;
2894     }
2895 
2896     if (rdt_mon_capable) {
2897         ret = alloc_rmid();
2898         if (ret < 0) {
2899             rdt_last_cmd_puts("Out of RMIDs\n");
2900             goto out_destroy;
2901         }
2902         rdtgrp->mon.rmid = ret;
2903 
2904         ret = mkdir_mondata_all(kn, rdtgrp, &rdtgrp->mon.mon_data_kn);
2905         if (ret) {
2906             rdt_last_cmd_puts("kernfs subdir error\n");
2907             goto out_idfree;
2908         }
2909     }
2910     kernfs_activate(kn);
2911 
2912     /*
2913      * The caller unlocks the parent_kn upon success.
2914      */
2915     return 0;
2916 
2917 out_idfree:
2918     free_rmid(rdtgrp->mon.rmid);
2919 out_destroy:
2920     kernfs_put(rdtgrp->kn);
2921     kernfs_remove(rdtgrp->kn);
2922 out_free_rgrp:
2923     kfree(rdtgrp);
2924 out_unlock:
2925     rdtgroup_kn_unlock(parent_kn);
2926     return ret;
2927 }
2928 
2929 static void mkdir_rdt_prepare_clean(struct rdtgroup *rgrp)
2930 {
2931     kernfs_remove(rgrp->kn);
2932     free_rmid(rgrp->mon.rmid);
2933     rdtgroup_remove(rgrp);
2934 }
2935 
2936 /*
2937  * Create a monitor group under "mon_groups" directory of a control
2938  * and monitor group(ctrl_mon). This is a resource group
2939  * to monitor a subset of tasks and cpus in its parent ctrl_mon group.
2940  */
2941 static int rdtgroup_mkdir_mon(struct kernfs_node *parent_kn,
2942                   const char *name, umode_t mode)
2943 {
2944     struct rdtgroup *rdtgrp, *prgrp;
2945     int ret;
2946 
2947     ret = mkdir_rdt_prepare(parent_kn, name, mode, RDTMON_GROUP, &rdtgrp);
2948     if (ret)
2949         return ret;
2950 
2951     prgrp = rdtgrp->mon.parent;
2952     rdtgrp->closid = prgrp->closid;
2953 
2954     /*
2955      * Add the rdtgrp to the list of rdtgrps the parent
2956      * ctrl_mon group has to track.
2957      */
2958     list_add_tail(&rdtgrp->mon.crdtgrp_list, &prgrp->mon.crdtgrp_list);
2959 
2960     rdtgroup_kn_unlock(parent_kn);
2961     return ret;
2962 }
2963 
2964 /*
2965  * These are rdtgroups created under the root directory. Can be used
2966  * to allocate and monitor resources.
2967  */
2968 static int rdtgroup_mkdir_ctrl_mon(struct kernfs_node *parent_kn,
2969                    const char *name, umode_t mode)
2970 {
2971     struct rdtgroup *rdtgrp;
2972     struct kernfs_node *kn;
2973     u32 closid;
2974     int ret;
2975 
2976     ret = mkdir_rdt_prepare(parent_kn, name, mode, RDTCTRL_GROUP, &rdtgrp);
2977     if (ret)
2978         return ret;
2979 
2980     kn = rdtgrp->kn;
2981     ret = closid_alloc();
2982     if (ret < 0) {
2983         rdt_last_cmd_puts("Out of CLOSIDs\n");
2984         goto out_common_fail;
2985     }
2986     closid = ret;
2987     ret = 0;
2988 
2989     rdtgrp->closid = closid;
2990     ret = rdtgroup_init_alloc(rdtgrp);
2991     if (ret < 0)
2992         goto out_id_free;
2993 
2994     list_add(&rdtgrp->rdtgroup_list, &rdt_all_groups);
2995 
2996     if (rdt_mon_capable) {
2997         /*
2998          * Create an empty mon_groups directory to hold the subset
2999          * of tasks and cpus to monitor.
3000          */
3001         ret = mongroup_create_dir(kn, rdtgrp, "mon_groups", NULL);
3002         if (ret) {
3003             rdt_last_cmd_puts("kernfs subdir error\n");
3004             goto out_del_list;
3005         }
3006     }
3007 
3008     goto out_unlock;
3009 
3010 out_del_list:
3011     list_del(&rdtgrp->rdtgroup_list);
3012 out_id_free:
3013     closid_free(closid);
3014 out_common_fail:
3015     mkdir_rdt_prepare_clean(rdtgrp);
3016 out_unlock:
3017     rdtgroup_kn_unlock(parent_kn);
3018     return ret;
3019 }
3020 
3021 /*
3022  * We allow creating mon groups only with in a directory called "mon_groups"
3023  * which is present in every ctrl_mon group. Check if this is a valid
3024  * "mon_groups" directory.
3025  *
3026  * 1. The directory should be named "mon_groups".
3027  * 2. The mon group itself should "not" be named "mon_groups".
3028  *   This makes sure "mon_groups" directory always has a ctrl_mon group
3029  *   as parent.
3030  */
3031 static bool is_mon_groups(struct kernfs_node *kn, const char *name)
3032 {
3033     return (!strcmp(kn->name, "mon_groups") &&
3034         strcmp(name, "mon_groups"));
3035 }
3036 
3037 static int rdtgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
3038               umode_t mode)
3039 {
3040     /* Do not accept '\n' to avoid unparsable situation. */
3041     if (strchr(name, '\n'))
3042         return -EINVAL;
3043 
3044     /*
3045      * If the parent directory is the root directory and RDT
3046      * allocation is supported, add a control and monitoring
3047      * subdirectory
3048      */
3049     if (rdt_alloc_capable && parent_kn == rdtgroup_default.kn)
3050         return rdtgroup_mkdir_ctrl_mon(parent_kn, name, mode);
3051 
3052     /*
3053      * If RDT monitoring is supported and the parent directory is a valid
3054      * "mon_groups" directory, add a monitoring subdirectory.
3055      */
3056     if (rdt_mon_capable && is_mon_groups(parent_kn, name))
3057         return rdtgroup_mkdir_mon(parent_kn, name, mode);
3058 
3059     return -EPERM;
3060 }
3061 
3062 static int rdtgroup_rmdir_mon(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
3063 {
3064     struct rdtgroup *prdtgrp = rdtgrp->mon.parent;
3065     int cpu;
3066 
3067     /* Give any tasks back to the parent group */
3068     rdt_move_group_tasks(rdtgrp, prdtgrp, tmpmask);
3069 
3070     /* Update per cpu rmid of the moved CPUs first */
3071     for_each_cpu(cpu, &rdtgrp->cpu_mask)
3072         per_cpu(pqr_state.default_rmid, cpu) = prdtgrp->mon.rmid;
3073     /*
3074      * Update the MSR on moved CPUs and CPUs which have moved
3075      * task running on them.
3076      */
3077     cpumask_or(tmpmask, tmpmask, &rdtgrp->cpu_mask);
3078     update_closid_rmid(tmpmask, NULL);
3079 
3080     rdtgrp->flags = RDT_DELETED;
3081     free_rmid(rdtgrp->mon.rmid);
3082 
3083     /*
3084      * Remove the rdtgrp from the parent ctrl_mon group's list
3085      */
3086     WARN_ON(list_empty(&prdtgrp->mon.crdtgrp_list));
3087     list_del(&rdtgrp->mon.crdtgrp_list);
3088 
3089     kernfs_remove(rdtgrp->kn);
3090 
3091     return 0;
3092 }
3093 
3094 static int rdtgroup_ctrl_remove(struct rdtgroup *rdtgrp)
3095 {
3096     rdtgrp->flags = RDT_DELETED;
3097     list_del(&rdtgrp->rdtgroup_list);
3098 
3099     kernfs_remove(rdtgrp->kn);
3100     return 0;
3101 }
3102 
3103 static int rdtgroup_rmdir_ctrl(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
3104 {
3105     int cpu;
3106 
3107     /* Give any tasks back to the default group */
3108     rdt_move_group_tasks(rdtgrp, &rdtgroup_default, tmpmask);
3109 
3110     /* Give any CPUs back to the default group */
3111     cpumask_or(&rdtgroup_default.cpu_mask,
3112            &rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);
3113 
3114     /* Update per cpu closid and rmid of the moved CPUs first */
3115     for_each_cpu(cpu, &rdtgrp->cpu_mask) {
3116         per_cpu(pqr_state.default_closid, cpu) = rdtgroup_default.closid;
3117         per_cpu(pqr_state.default_rmid, cpu) = rdtgroup_default.mon.rmid;
3118     }
3119 
3120     /*
3121      * Update the MSR on moved CPUs and CPUs which have moved
3122      * task running on them.
3123      */
3124     cpumask_or(tmpmask, tmpmask, &rdtgrp->cpu_mask);
3125     update_closid_rmid(tmpmask, NULL);
3126 
3127     closid_free(rdtgrp->closid);
3128     free_rmid(rdtgrp->mon.rmid);
3129 
3130     rdtgroup_ctrl_remove(rdtgrp);
3131 
3132     /*
3133      * Free all the child monitor group rmids.
3134      */
3135     free_all_child_rdtgrp(rdtgrp);
3136 
3137     return 0;
3138 }
3139 
3140 static int rdtgroup_rmdir(struct kernfs_node *kn)
3141 {
3142     struct kernfs_node *parent_kn = kn->parent;
3143     struct rdtgroup *rdtgrp;
3144     cpumask_var_t tmpmask;
3145     int ret = 0;
3146 
3147     if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL))
3148         return -ENOMEM;
3149 
3150     rdtgrp = rdtgroup_kn_lock_live(kn);
3151     if (!rdtgrp) {
3152         ret = -EPERM;
3153         goto out;
3154     }
3155 
3156     /*
3157      * If the rdtgroup is a ctrl_mon group and parent directory
3158      * is the root directory, remove the ctrl_mon group.
3159      *
3160      * If the rdtgroup is a mon group and parent directory
3161      * is a valid "mon_groups" directory, remove the mon group.
3162      */
3163     if (rdtgrp->type == RDTCTRL_GROUP && parent_kn == rdtgroup_default.kn &&
3164         rdtgrp != &rdtgroup_default) {
3165         if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
3166             rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
3167             ret = rdtgroup_ctrl_remove(rdtgrp);
3168         } else {
3169             ret = rdtgroup_rmdir_ctrl(rdtgrp, tmpmask);
3170         }
3171     } else if (rdtgrp->type == RDTMON_GROUP &&
3172          is_mon_groups(parent_kn, kn->name)) {
3173         ret = rdtgroup_rmdir_mon(rdtgrp, tmpmask);
3174     } else {
3175         ret = -EPERM;
3176     }
3177 
3178 out:
3179     rdtgroup_kn_unlock(kn);
3180     free_cpumask_var(tmpmask);
3181     return ret;
3182 }
3183 
3184 static int rdtgroup_show_options(struct seq_file *seq, struct kernfs_root *kf)
3185 {
3186     if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L3))
3187         seq_puts(seq, ",cdp");
3188 
3189     if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L2))
3190         seq_puts(seq, ",cdpl2");
3191 
3192     if (is_mba_sc(&rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl))
3193         seq_puts(seq, ",mba_MBps");
3194 
3195     return 0;
3196 }
3197 
3198 static struct kernfs_syscall_ops rdtgroup_kf_syscall_ops = {
3199     .mkdir      = rdtgroup_mkdir,
3200     .rmdir      = rdtgroup_rmdir,
3201     .show_options   = rdtgroup_show_options,
3202 };
3203 
3204 static int __init rdtgroup_setup_root(void)
3205 {
3206     int ret;
3207 
3208     rdt_root = kernfs_create_root(&rdtgroup_kf_syscall_ops,
3209                       KERNFS_ROOT_CREATE_DEACTIVATED |
3210                       KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK,
3211                       &rdtgroup_default);
3212     if (IS_ERR(rdt_root))
3213         return PTR_ERR(rdt_root);
3214 
3215     mutex_lock(&rdtgroup_mutex);
3216 
3217     rdtgroup_default.closid = 0;
3218     rdtgroup_default.mon.rmid = 0;
3219     rdtgroup_default.type = RDTCTRL_GROUP;
3220     INIT_LIST_HEAD(&rdtgroup_default.mon.crdtgrp_list);
3221 
3222     list_add(&rdtgroup_default.rdtgroup_list, &rdt_all_groups);
3223 
3224     ret = rdtgroup_add_files(kernfs_root_to_node(rdt_root), RF_CTRL_BASE);
3225     if (ret) {
3226         kernfs_destroy_root(rdt_root);
3227         goto out;
3228     }
3229 
3230     rdtgroup_default.kn = kernfs_root_to_node(rdt_root);
3231     kernfs_activate(rdtgroup_default.kn);
3232 
3233 out:
3234     mutex_unlock(&rdtgroup_mutex);
3235 
3236     return ret;
3237 }
3238 
3239 /*
3240  * rdtgroup_init - rdtgroup initialization
3241  *
3242  * Setup resctrl file system including set up root, create mount point,
3243  * register rdtgroup filesystem, and initialize files under root directory.
3244  *
3245  * Return: 0 on success or -errno
3246  */
3247 int __init rdtgroup_init(void)
3248 {
3249     int ret = 0;
3250 
3251     seq_buf_init(&last_cmd_status, last_cmd_status_buf,
3252              sizeof(last_cmd_status_buf));
3253 
3254     ret = rdtgroup_setup_root();
3255     if (ret)
3256         return ret;
3257 
3258     ret = sysfs_create_mount_point(fs_kobj, "resctrl");
3259     if (ret)
3260         goto cleanup_root;
3261 
3262     ret = register_filesystem(&rdt_fs_type);
3263     if (ret)
3264         goto cleanup_mountpoint;
3265 
3266     /*
3267      * Adding the resctrl debugfs directory here may not be ideal since
3268      * it would let the resctrl debugfs directory appear on the debugfs
3269      * filesystem before the resctrl filesystem is mounted.
3270      * It may also be ok since that would enable debugging of RDT before
3271      * resctrl is mounted.
3272      * The reason why the debugfs directory is created here and not in
3273      * rdt_get_tree() is because rdt_get_tree() takes rdtgroup_mutex and
3274      * during the debugfs directory creation also &sb->s_type->i_mutex_key
3275      * (the lockdep class of inode->i_rwsem). Other filesystem
3276      * interactions (eg. SyS_getdents) have the lock ordering:
3277      * &sb->s_type->i_mutex_key --> &mm->mmap_lock
3278      * During mmap(), called with &mm->mmap_lock, the rdtgroup_mutex
3279      * is taken, thus creating dependency:
3280      * &mm->mmap_lock --> rdtgroup_mutex for the latter that can cause
3281      * issues considering the other two lock dependencies.
3282      * By creating the debugfs directory here we avoid a dependency
3283      * that may cause deadlock (even though file operations cannot
3284      * occur until the filesystem is mounted, but I do not know how to
3285      * tell lockdep that).
3286      */
3287     debugfs_resctrl = debugfs_create_dir("resctrl", NULL);
3288 
3289     return 0;
3290 
3291 cleanup_mountpoint:
3292     sysfs_remove_mount_point(fs_kobj, "resctrl");
3293 cleanup_root:
3294     kernfs_destroy_root(rdt_root);
3295 
3296     return ret;
3297 }
3298 
3299 void __exit rdtgroup_exit(void)
3300 {
3301     debugfs_remove_recursive(debugfs_resctrl);
3302     unregister_filesystem(&rdt_fs_type);
3303     sysfs_remove_mount_point(fs_kobj, "resctrl");
3304     kernfs_destroy_root(rdt_root);
3305 }