Merge branch 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 cache allocation interface from Thomas Gleixner:
 "This provides support for Intel's Cache Allocation Technology, a cache
  partitioning mechanism.

  The interface is odd, but the hardware interface of that CAT stuff is
  odd as well.

  We tried hard to come up with an abstraction, but that only allows
  rather simple partitioning, but no way of sharing and dealing with the
  per package nature of this mechanism.

  In the end we decided to expose the allocation bitmaps directly so all
  combinations of the hardware can be utilized.

  There are two ways of associating a cache partition:

   - Task

     A task can be added to a resource group. It uses the cache
     partition associated to the group.

   - CPU

     All tasks which are not member of a resource group use the group to
     which the CPU they are running on is associated with.

     That allows for simple CPU based partitioning schemes.

  The main expected user sare:

   - Virtualization so a VM can only trash only the associated part of
     the cash w/o disturbing others

   - Real-Time systems to seperate RT and general workloads.

   - Latency sensitive enterprise workloads

   - In theory this also can be used to protect against cache side
     channel attacks"

[ Intel RDT is "Resource Director Technology". The interface really is
  rather odd and very specific, which delayed this pull request while I
  was thinking about it. The pull request itself came in early during
  the merge window, I just delayed it until things had calmed down and I
  had more time.

  But people tell me they'll use this, and the good news is that it is
  _so_ specific that it's rather independent of anything else, and no
  user is going to depend on the interface since it's pretty rare. So if
  push comes to shove, we can just remove the interface and nothing will
  break ]

* 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (31 commits)
  x86/intel_rdt: Implement show_options() for resctrlfs
  x86/intel_rdt: Call intel_rdt_sched_in() with preemption disabled
  x86/intel_rdt: Update task closid immediately on CPU in rmdir and unmount
  x86/intel_rdt: Fix setting of closid when adding CPUs to a group
  x86/intel_rdt: Update percpu closid immeditately on CPUs affected by changee
  x86/intel_rdt: Reset per cpu closids on unmount
  x86/intel_rdt: Select KERNFS when enabling INTEL_RDT_A
  x86/intel_rdt: Prevent deadlock against hotplug lock
  x86/intel_rdt: Protect info directory from removal
  x86/intel_rdt: Add info files to Documentation
  x86/intel_rdt: Export the minimum number of set mask bits in sysfs
  x86/intel_rdt: Propagate error in rdt_mount() properly
  x86/intel_rdt: Add a missing #include
  MAINTAINERS: Add maintainer for Intel RDT resource allocation
  x86/intel_rdt: Add scheduler hook
  x86/intel_rdt: Add schemata file
  x86/intel_rdt: Add tasks files
  x86/intel_rdt: Add cpus file
  x86/intel_rdt: Add mkdir to resctrl file system
  x86/intel_rdt: Add "info" files to resctrl file system
  ...

1 files changed, 1115 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
new file mode 100644
index 000000000000..8af04afdfcb9
--- /dev/null
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -0,0 +1,1115 @@
+/*
+ * User interface for Resource Alloction in Resource Director Technology(RDT)
+ *
+ * Copyright (C) 2016 Intel Corporation
+ *
+ * Author: Fenghua Yu <fenghua.yu@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * More information about RDT be found in the Intel (R) x86 Architecture
+ * Software Developer Manual.
+ */
+
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
+#include <linux/cpu.h>
+#include <linux/fs.h>
+#include <linux/sysfs.h>
+#include <linux/kernfs.h>
+#include <linux/seq_file.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/cpu.h>
+#include <linux/task_work.h>
+
+#include <uapi/linux/magic.h>
+
+#include <asm/intel_rdt.h>
+#include <asm/intel_rdt_common.h>
+
+DEFINE_STATIC_KEY_FALSE(rdt_enable_key);
+struct kernfs_root *rdt_root;
+struct rdtgroup rdtgroup_default;
+LIST_HEAD(rdt_all_groups);
+
+/* Kernel fs node for "info" directory under root */
+static struct kernfs_node *kn_info;
+
+/*
+ * Trivial allocator for CLOSIDs. Since h/w only supports a small number,
+ * we can keep a bitmap of free CLOSIDs in a single integer.
+ *
+ * Using a global CLOSID across all resources has some advantages and
+ * some drawbacks:
+ * + We can simply set "current->closid" to assign a task to a resource
+ *   group.
+ * + Context switch code can avoid extra memory references deciding which
+ *   CLOSID to load into the PQR_ASSOC MSR
+ * - We give up some options in configuring resource groups across multi-socket
+ *   systems.
+ * - Our choices on how to configure each resource become progressively more
+ *   limited as the number of resources grows.
+ */
+static int closid_free_map;
+
+static void closid_init(void)
+{
+	struct rdt_resource *r;
+	int rdt_min_closid = 32;
+
+	/* Compute rdt_min_closid across all resources */
+	for_each_enabled_rdt_resource(r)
+		rdt_min_closid = min(rdt_min_closid, r->num_closid);
+
+	closid_free_map = BIT_MASK(rdt_min_closid) - 1;
+
+	/* CLOSID 0 is always reserved for the default group */
+	closid_free_map &= ~1;
+}
+
+int closid_alloc(void)
+{
+	int closid = ffs(closid_free_map);
+
+	if (closid == 0)
+		return -ENOSPC;
+	closid--;
+	closid_free_map &= ~(1 << closid);
+
+	return closid;
+}
+
+static void closid_free(int closid)
+{
+	closid_free_map |= 1 << closid;
+}
+
+/* set uid and gid of rdtgroup dirs and files to that of the creator */
+static int rdtgroup_kn_set_ugid(struct kernfs_node *kn)
+{
+	struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID,
+				.ia_uid = current_fsuid(),
+				.ia_gid = current_fsgid(), };
+
+	if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) &&
+	    gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID))
+		return 0;
+
+	return kernfs_setattr(kn, &iattr);
+}
+
+static int rdtgroup_add_file(struct kernfs_node *parent_kn, struct rftype *rft)
+{
+	struct kernfs_node *kn;
+	int ret;
+
+	kn = __kernfs_create_file(parent_kn, rft->name, rft->mode,
+				  0, rft->kf_ops, rft, NULL, NULL);
+	if (IS_ERR(kn))
+		return PTR_ERR(kn);
+
+	ret = rdtgroup_kn_set_ugid(kn);
+	if (ret) {
+		kernfs_remove(kn);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int rdtgroup_add_files(struct kernfs_node *kn, struct rftype *rfts,
+			      int len)
+{
+	struct rftype *rft;
+	int ret;
+
+	lockdep_assert_held(&rdtgroup_mutex);
+
+	for (rft = rfts; rft < rfts + len; rft++) {
+		ret = rdtgroup_add_file(kn, rft);
+		if (ret)
+			goto error;
+	}
+
+	return 0;
+error:
+	pr_warn("Failed to add %s, err=%d\n", rft->name, ret);
+	while (--rft >= rfts)
+		kernfs_remove_by_name(kn, rft->name);
+	return ret;
+}
+
+static int rdtgroup_seqfile_show(struct seq_file *m, void *arg)
+{
+	struct kernfs_open_file *of = m->private;
+	struct rftype *rft = of->kn->priv;
+
+	if (rft->seq_show)
+		return rft->seq_show(of, m, arg);
+	return 0;
+}
+
+static ssize_t rdtgroup_file_write(struct kernfs_open_file *of, char *buf,
+				   size_t nbytes, loff_t off)
+{
+	struct rftype *rft = of->kn->priv;
+
+	if (rft->write)
+		return rft->write(of, buf, nbytes, off);
+
+	return -EINVAL;
+}
+
+static struct kernfs_ops rdtgroup_kf_single_ops = {
+	.atomic_write_len	= PAGE_SIZE,
+	.write			= rdtgroup_file_write,
+	.seq_show		= rdtgroup_seqfile_show,
+};
+
+static int rdtgroup_cpus_show(struct kernfs_open_file *of,
+			      struct seq_file *s, void *v)
+{
+	struct rdtgroup *rdtgrp;
+	int ret = 0;
+
+	rdtgrp = rdtgroup_kn_lock_live(of->kn);
+
+	if (rdtgrp)
+		seq_printf(s, "%*pb\n", cpumask_pr_args(&rdtgrp->cpu_mask));
+	else
+		ret = -ENOENT;
+	rdtgroup_kn_unlock(of->kn);
+
+	return ret;
+}
+
+/*
+ * This is safe against intel_rdt_sched_in() called from __switch_to()
+ * because __switch_to() is executed with interrupts disabled. A local call
+ * from rdt_update_closid() is proteced against __switch_to() because
+ * preemption is disabled.
+ */
+static void rdt_update_cpu_closid(void *closid)
+{
+	if (closid)
+		this_cpu_write(cpu_closid, *(int *)closid);
+	/*
+	 * We cannot unconditionally write the MSR because the current
+	 * executing task might have its own closid selected. Just reuse
+	 * the context switch code.
+	 */
+	intel_rdt_sched_in();
+}
+
+/*
+ * Update the PGR_ASSOC MSR on all cpus in @cpu_mask,
+ *
+ * Per task closids must have been set up before calling this function.
+ *
+ * The per cpu closids are updated with the smp function call, when @closid
+ * is not NULL. If @closid is NULL then all affected percpu closids must
+ * have been set up before calling this function.
+ */
+static void
+rdt_update_closid(const struct cpumask *cpu_mask, int *closid)
+{
+	int cpu = get_cpu();
+
+	if (cpumask_test_cpu(cpu, cpu_mask))
+		rdt_update_cpu_closid(closid);
+	smp_call_function_many(cpu_mask, rdt_update_cpu_closid, closid, 1);
+	put_cpu();
+}
+
+static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
+				   char *buf, size_t nbytes, loff_t off)
+{
+	cpumask_var_t tmpmask, newmask;
+	struct rdtgroup *rdtgrp, *r;
+	int ret;
+
+	if (!buf)
+		return -EINVAL;
+
+	if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL))
+		return -ENOMEM;
+	if (!zalloc_cpumask_var(&newmask, GFP_KERNEL)) {
+		free_cpumask_var(tmpmask);
+		return -ENOMEM;
+	}
+
+	rdtgrp = rdtgroup_kn_lock_live(of->kn);
+	if (!rdtgrp) {
+		ret = -ENOENT;
+		goto unlock;
+	}
+
+	ret = cpumask_parse(buf, newmask);
+	if (ret)
+		goto unlock;
+
+	/* check that user didn't specify any offline cpus */
+	cpumask_andnot(tmpmask, newmask, cpu_online_mask);
+	if (cpumask_weight(tmpmask)) {
+		ret = -EINVAL;
+		goto unlock;
+	}
+
+	/* Check whether cpus are dropped from this group */
+	cpumask_andnot(tmpmask, &rdtgrp->cpu_mask, newmask);
+	if (cpumask_weight(tmpmask)) {
+		/* Can't drop from default group */
+		if (rdtgrp == &rdtgroup_default) {
+			ret = -EINVAL;
+			goto unlock;
+		}
+		/* Give any dropped cpus to rdtgroup_default */
+		cpumask_or(&rdtgroup_default.cpu_mask,
+			   &rdtgroup_default.cpu_mask, tmpmask);
+		rdt_update_closid(tmpmask, &rdtgroup_default.closid);
+	}
+
+	/*
+	 * If we added cpus, remove them from previous group that owned them
+	 * and update per-cpu closid
+	 */
+	cpumask_andnot(tmpmask, newmask, &rdtgrp->cpu_mask);
+	if (cpumask_weight(tmpmask)) {
+		list_for_each_entry(r, &rdt_all_groups, rdtgroup_list) {
+			if (r == rdtgrp)
+				continue;
+			cpumask_andnot(&r->cpu_mask, &r->cpu_mask, tmpmask);
+		}
+		rdt_update_closid(tmpmask, &rdtgrp->closid);
+	}
+
+	/* Done pushing/pulling - update this group with new mask */
+	cpumask_copy(&rdtgrp->cpu_mask, newmask);
+
+unlock:
+	rdtgroup_kn_unlock(of->kn);
+	free_cpumask_var(tmpmask);
+	free_cpumask_var(newmask);
+
+	return ret ?: nbytes;
+}
+
+struct task_move_callback {
+	struct callback_head	work;
+	struct rdtgroup		*rdtgrp;
+};
+
+static void move_myself(struct callback_head *head)
+{
+	struct task_move_callback *callback;
+	struct rdtgroup *rdtgrp;
+
+	callback = container_of(head, struct task_move_callback, work);
+	rdtgrp = callback->rdtgrp;
+
+	/*
+	 * If resource group was deleted before this task work callback
+	 * was invoked, then assign the task to root group and free the
+	 * resource group.
+	 */
+	if (atomic_dec_and_test(&rdtgrp->waitcount) &&
+	    (rdtgrp->flags & RDT_DELETED)) {
+		current->closid = 0;
+		kfree(rdtgrp);
+	}
+
+	preempt_disable();
+	/* update PQR_ASSOC MSR to make resource group go into effect */
+	intel_rdt_sched_in();
+	preempt_enable();
+
+	kfree(callback);
+}
+
+static int __rdtgroup_move_task(struct task_struct *tsk,
+				struct rdtgroup *rdtgrp)
+{
+	struct task_move_callback *callback;
+	int ret;
+
+	callback = kzalloc(sizeof(*callback), GFP_KERNEL);
+	if (!callback)
+		return -ENOMEM;
+	callback->work.func = move_myself;
+	callback->rdtgrp = rdtgrp;
+
+	/*
+	 * Take a refcount, so rdtgrp cannot be freed before the
+	 * callback has been invoked.
+	 */
+	atomic_inc(&rdtgrp->waitcount);
+	ret = task_work_add(tsk, &callback->work, true);
+	if (ret) {
+		/*
+		 * Task is exiting. Drop the refcount and free the callback.
+		 * No need to check the refcount as the group cannot be
+		 * deleted before the write function unlocks rdtgroup_mutex.
+		 */
+		atomic_dec(&rdtgrp->waitcount);
+		kfree(callback);
+	} else {
+		tsk->closid = rdtgrp->closid;
+	}
+	return ret;
+}
+
+static int rdtgroup_task_write_permission(struct task_struct *task,
+					  struct kernfs_open_file *of)
+{
+	const struct cred *tcred = get_task_cred(task);
+	const struct cred *cred = current_cred();
+	int ret = 0;
+
+	/*
+	 * Even if we're attaching all tasks in the thread group, we only
+	 * need to check permissions on one of them.
+	 */
+	if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
+	    !uid_eq(cred->euid, tcred->uid) &&
+	    !uid_eq(cred->euid, tcred->suid))
+		ret = -EPERM;
+
+	put_cred(tcred);
+	return ret;
+}
+
+static int rdtgroup_move_task(pid_t pid, struct rdtgroup *rdtgrp,
+			      struct kernfs_open_file *of)
+{
+	struct task_struct *tsk;
+	int ret;
+
+	rcu_read_lock();
+	if (pid) {
+		tsk = find_task_by_vpid(pid);
+		if (!tsk) {
+			rcu_read_unlock();
+			return -ESRCH;
+		}
+	} else {
+		tsk = current;
+	}
+
+	get_task_struct(tsk);
+	rcu_read_unlock();
+
+	ret = rdtgroup_task_write_permission(tsk, of);
+	if (!ret)
+		ret = __rdtgroup_move_task(tsk, rdtgrp);
+
+	put_task_struct(tsk);
+	return ret;
+}
+
+static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
+				    char *buf, size_t nbytes, loff_t off)
+{
+	struct rdtgroup *rdtgrp;
+	int ret = 0;
+	pid_t pid;
+
+	if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
+		return -EINVAL;
+	rdtgrp = rdtgroup_kn_lock_live(of->kn);
+
+	if (rdtgrp)
+		ret = rdtgroup_move_task(pid, rdtgrp, of);
+	else
+		ret = -ENOENT;
+
+	rdtgroup_kn_unlock(of->kn);
+
+	return ret ?: nbytes;
+}
+
+static void show_rdt_tasks(struct rdtgroup *r, struct seq_file *s)
+{
+	struct task_struct *p, *t;
+
+	rcu_read_lock();
+	for_each_process_thread(p, t) {
+		if (t->closid == r->closid)
+			seq_printf(s, "%d\n", t->pid);
+	}
+	rcu_read_unlock();
+}
+
+static int rdtgroup_tasks_show(struct kernfs_open_file *of,
+			       struct seq_file *s, void *v)
+{
+	struct rdtgroup *rdtgrp;
+	int ret = 0;
+
+	rdtgrp = rdtgroup_kn_lock_live(of->kn);
+	if (rdtgrp)
+		show_rdt_tasks(rdtgrp, s);
+	else
+		ret = -ENOENT;
+	rdtgroup_kn_unlock(of->kn);
+
+	return ret;
+}
+
+/* Files in each rdtgroup */
+static struct rftype rdtgroup_base_files[] = {
+	{
+		.name		= "cpus",
+		.mode		= 0644,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.write		= rdtgroup_cpus_write,
+		.seq_show	= rdtgroup_cpus_show,
+	},
+	{
+		.name		= "tasks",
+		.mode		= 0644,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.write		= rdtgroup_tasks_write,
+		.seq_show	= rdtgroup_tasks_show,
+	},
+	{
+		.name		= "schemata",
+		.mode		= 0644,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.write		= rdtgroup_schemata_write,
+		.seq_show	= rdtgroup_schemata_show,
+	},
+};
+
+static int rdt_num_closids_show(struct kernfs_open_file *of,
+				struct seq_file *seq, void *v)
+{
+	struct rdt_resource *r = of->kn->parent->priv;
+
+	seq_printf(seq, "%d\n", r->num_closid);
+
+	return 0;
+}
+
+static int rdt_cbm_mask_show(struct kernfs_open_file *of,
+			     struct seq_file *seq, void *v)
+{
+	struct rdt_resource *r = of->kn->parent->priv;
+
+	seq_printf(seq, "%x\n", r->max_cbm);
+
+	return 0;
+}
+
+static int rdt_min_cbm_bits_show(struct kernfs_open_file *of,
+			     struct seq_file *seq, void *v)
+{
+	struct rdt_resource *r = of->kn->parent->priv;
+
+	seq_printf(seq, "%d\n", r->min_cbm_bits);
+
+	return 0;
+}
+
+/* rdtgroup information files for one cache resource. */
+static struct rftype res_info_files[] = {
+	{
+		.name		= "num_closids",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= rdt_num_closids_show,
+	},
+	{
+		.name		= "cbm_mask",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= rdt_cbm_mask_show,
+	},
+	{
+		.name		= "min_cbm_bits",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= rdt_min_cbm_bits_show,
+	},
+};
+
+static int rdtgroup_create_info_dir(struct kernfs_node *parent_kn)
+{
+	struct kernfs_node *kn_subdir;
+	struct rdt_resource *r;
+	int ret;
+
+	/* create the directory */
+	kn_info = kernfs_create_dir(parent_kn, "info", parent_kn->mode, NULL);
+	if (IS_ERR(kn_info))
+		return PTR_ERR(kn_info);
+	kernfs_get(kn_info);
+
+	for_each_enabled_rdt_resource(r) {
+		kn_subdir = kernfs_create_dir(kn_info, r->name,
+					      kn_info->mode, r);
+		if (IS_ERR(kn_subdir)) {
+			ret = PTR_ERR(kn_subdir);
+			goto out_destroy;
+		}
+		kernfs_get(kn_subdir);
+		ret = rdtgroup_kn_set_ugid(kn_subdir);
+		if (ret)
+			goto out_destroy;
+		ret = rdtgroup_add_files(kn_subdir, res_info_files,
+					 ARRAY_SIZE(res_info_files));
+		if (ret)
+			goto out_destroy;
+		kernfs_activate(kn_subdir);
+	}
+
+	/*
+	 * This extra ref will be put in kernfs_remove() and guarantees
+	 * that @rdtgrp->kn is always accessible.
+	 */
+	kernfs_get(kn_info);
+
+	ret = rdtgroup_kn_set_ugid(kn_info);
+	if (ret)
+		goto out_destroy;
+
+	kernfs_activate(kn_info);
+
+	return 0;
+
+out_destroy:
+	kernfs_remove(kn_info);
+	return ret;
+}
+
+static void l3_qos_cfg_update(void *arg)
+{
+	bool *enable = arg;
+
+	wrmsrl(IA32_L3_QOS_CFG, *enable ? L3_QOS_CDP_ENABLE : 0ULL);
+}
+
+static int set_l3_qos_cfg(struct rdt_resource *r, bool enable)
+{
+	cpumask_var_t cpu_mask;
+	struct rdt_domain *d;
+	int cpu;
+
+	if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL))
+		return -ENOMEM;
+
+	list_for_each_entry(d, &r->domains, list) {
+		/* Pick one CPU from each domain instance to update MSR */
+		cpumask_set_cpu(cpumask_any(&d->cpu_mask), cpu_mask);
+	}
+	cpu = get_cpu();
+	/* Update QOS_CFG MSR on this cpu if it's in cpu_mask. */
+	if (cpumask_test_cpu(cpu, cpu_mask))
+		l3_qos_cfg_update(&enable);
+	/* Update QOS_CFG MSR on all other cpus in cpu_mask. */
+	smp_call_function_many(cpu_mask, l3_qos_cfg_update, &enable, 1);
+	put_cpu();
+
+	free_cpumask_var(cpu_mask);
+
+	return 0;
+}
+
+static int cdp_enable(void)
+{
+	struct rdt_resource *r_l3data = &rdt_resources_all[RDT_RESOURCE_L3DATA];
+	struct rdt_resource *r_l3code = &rdt_resources_all[RDT_RESOURCE_L3CODE];
+	struct rdt_resource *r_l3 = &rdt_resources_all[RDT_RESOURCE_L3];
+	int ret;
+
+	if (!r_l3->capable || !r_l3data->capable || !r_l3code->capable)
+		return -EINVAL;
+
+	ret = set_l3_qos_cfg(r_l3, true);
+	if (!ret) {
+		r_l3->enabled = false;
+		r_l3data->enabled = true;
+		r_l3code->enabled = true;
+	}
+	return ret;
+}
+
+static void cdp_disable(void)
+{
+	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3];
+
+	r->enabled = r->capable;
+
+	if (rdt_resources_all[RDT_RESOURCE_L3DATA].enabled) {
+		rdt_resources_all[RDT_RESOURCE_L3DATA].enabled = false;
+		rdt_resources_all[RDT_RESOURCE_L3CODE].enabled = false;
+		set_l3_qos_cfg(r, false);
+	}
+}
+
+static int parse_rdtgroupfs_options(char *data)
+{
+	char *token, *o = data;
+	int ret = 0;
+
+	while ((token = strsep(&o, ",")) != NULL) {
+		if (!*token)
+			return -EINVAL;
+
+		if (!strcmp(token, "cdp"))
+			ret = cdp_enable();
+	}
+
+	return ret;
+}
+
+/*
+ * We don't allow rdtgroup directories to be created anywhere
+ * except the root directory. Thus when looking for the rdtgroup
+ * structure for a kernfs node we are either looking at a directory,
+ * in which case the rdtgroup structure is pointed at by the "priv"
+ * field, otherwise we have a file, and need only look to the parent
+ * to find the rdtgroup.
+ */
+static struct rdtgroup *kernfs_to_rdtgroup(struct kernfs_node *kn)
+{
+	if (kernfs_type(kn) == KERNFS_DIR) {
+		/*
+		 * All the resource directories use "kn->priv"
+		 * to point to the "struct rdtgroup" for the
+		 * resource. "info" and its subdirectories don't
+		 * have rdtgroup structures, so return NULL here.
+		 */
+		if (kn == kn_info || kn->parent == kn_info)
+			return NULL;
+		else
+			return kn->priv;
+	} else {
+		return kn->parent->priv;
+	}
+}
+
+struct rdtgroup *rdtgroup_kn_lock_live(struct kernfs_node *kn)
+{
+	struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn);
+
+	if (!rdtgrp)
+		return NULL;
+
+	atomic_inc(&rdtgrp->waitcount);
+	kernfs_break_active_protection(kn);
+
+	mutex_lock(&rdtgroup_mutex);
+
+	/* Was this group deleted while we waited? */
+	if (rdtgrp->flags & RDT_DELETED)
+		return NULL;
+
+	return rdtgrp;
+}
+
+void rdtgroup_kn_unlock(struct kernfs_node *kn)
+{
+	struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn);
+
+	if (!rdtgrp)
+		return;
+
+	mutex_unlock(&rdtgroup_mutex);
+
+	if (atomic_dec_and_test(&rdtgrp->waitcount) &&
+	    (rdtgrp->flags & RDT_DELETED)) {
+		kernfs_unbreak_active_protection(kn);
+		kernfs_put(kn);
+		kfree(rdtgrp);
+	} else {
+		kernfs_unbreak_active_protection(kn);
+	}
+}
+
+static struct dentry *rdt_mount(struct file_system_type *fs_type,
+				int flags, const char *unused_dev_name,
+				void *data)
+{
+	struct dentry *dentry;
+	int ret;
+
+	mutex_lock(&rdtgroup_mutex);
+	/*
+	 * resctrl file system can only be mounted once.
+	 */
+	if (static_branch_unlikely(&rdt_enable_key)) {
+		dentry = ERR_PTR(-EBUSY);
+		goto out;
+	}
+
+	ret = parse_rdtgroupfs_options(data);
+	if (ret) {
+		dentry = ERR_PTR(ret);
+		goto out_cdp;
+	}
+
+	closid_init();
+
+	ret = rdtgroup_create_info_dir(rdtgroup_default.kn);
+	if (ret) {
+		dentry = ERR_PTR(ret);
+		goto out_cdp;
+	}
+
+	dentry = kernfs_mount(fs_type, flags, rdt_root,
+			      RDTGROUP_SUPER_MAGIC, NULL);
+	if (IS_ERR(dentry))
+		goto out_cdp;
+
+	static_branch_enable(&rdt_enable_key);
+	goto out;
+
+out_cdp:
+	cdp_disable();
+out:
+	mutex_unlock(&rdtgroup_mutex);
+
+	return dentry;
+}
+
+static int reset_all_cbms(struct rdt_resource *r)
+{
+	struct msr_param msr_param;
+	cpumask_var_t cpu_mask;
+	struct rdt_domain *d;
+	int i, cpu;
+
+	if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL))
+		return -ENOMEM;
+
+	msr_param.res = r;
+	msr_param.low = 0;
+	msr_param.high = r->num_closid;
+
+	/*
+	 * Disable resource control for this resource by setting all
+	 * CBMs in all domains to the maximum mask value. Pick one CPU
+	 * from each domain to update the MSRs below.
+	 */
+	list_for_each_entry(d, &r->domains, list) {
+		cpumask_set_cpu(cpumask_any(&d->cpu_mask), cpu_mask);
+
+		for (i = 0; i < r->num_closid; i++)
+			d->cbm[i] = r->max_cbm;
+	}
+	cpu = get_cpu();
+	/* Update CBM on this cpu if it's in cpu_mask. */
+	if (cpumask_test_cpu(cpu, cpu_mask))
+		rdt_cbm_update(&msr_param);
+	/* Update CBM on all other cpus in cpu_mask. */
+	smp_call_function_many(cpu_mask, rdt_cbm_update, &msr_param, 1);
+	put_cpu();
+
+	free_cpumask_var(cpu_mask);
+
+	return 0;
+}
+
+/*
+ * Move tasks from one to the other group. If @from is NULL, then all tasks
+ * in the systems are moved unconditionally (used for teardown).
+ *
+ * If @mask is not NULL the cpus on which moved tasks are running are set
+ * in that mask so the update smp function call is restricted to affected
+ * cpus.
+ */
+static void rdt_move_group_tasks(struct rdtgroup *from, struct rdtgroup *to,
+				 struct cpumask *mask)
+{
+	struct task_struct *p, *t;
+
+	read_lock(&tasklist_lock);
+	for_each_process_thread(p, t) {
+		if (!from || t->closid == from->closid) {
+			t->closid = to->closid;
+#ifdef CONFIG_SMP
+			/*
+			 * This is safe on x86 w/o barriers as the ordering
+			 * of writing to task_cpu() and t->on_cpu is
+			 * reverse to the reading here. The detection is
+			 * inaccurate as tasks might move or schedule
+			 * before the smp function call takes place. In
+			 * such a case the function call is pointless, but
+			 * there is no other side effect.
+			 */
+			if (mask && t->on_cpu)
+				cpumask_set_cpu(task_cpu(t), mask);
+#endif
+		}
+	}
+	read_unlock(&tasklist_lock);
+}
+
+/*
+ * Forcibly remove all of subdirectories under root.
+ */
+static void rmdir_all_sub(void)
+{
+	struct rdtgroup *rdtgrp, *tmp;
+
+	/* Move all tasks to the default resource group */
+	rdt_move_group_tasks(NULL, &rdtgroup_default, NULL);
+
+	list_for_each_entry_safe(rdtgrp, tmp, &rdt_all_groups, rdtgroup_list) {
+		/* Remove each rdtgroup other than root */
+		if (rdtgrp == &rdtgroup_default)
+			continue;
+
+		/*
+		 * Give any CPUs back to the default group. We cannot copy
+		 * cpu_online_mask because a CPU might have executed the
+		 * offline callback already, but is still marked online.
+		 */
+		cpumask_or(&rdtgroup_default.cpu_mask,
+			   &rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);
+
+		kernfs_remove(rdtgrp->kn);
+		list_del(&rdtgrp->rdtgroup_list);
+		kfree(rdtgrp);
+	}
+	/* Notify online CPUs to update per cpu storage and PQR_ASSOC MSR */
+	get_online_cpus();
+	rdt_update_closid(cpu_online_mask, &rdtgroup_default.closid);
+	put_online_cpus();
+
+	kernfs_remove(kn_info);
+}
+
+static void rdt_kill_sb(struct super_block *sb)
+{
+	struct rdt_resource *r;
+
+	mutex_lock(&rdtgroup_mutex);
+
+	/*Put everything back to default values. */
+	for_each_enabled_rdt_resource(r)
+		reset_all_cbms(r);
+	cdp_disable();
+	rmdir_all_sub();
+	static_branch_disable(&rdt_enable_key);
+	kernfs_kill_sb(sb);
+	mutex_unlock(&rdtgroup_mutex);
+}
+
+static struct file_system_type rdt_fs_type = {
+	.name    = "resctrl",
+	.mount   = rdt_mount,
+	.kill_sb = rdt_kill_sb,
+};
+
+static int rdtgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
+			  umode_t mode)
+{
+	struct rdtgroup *parent, *rdtgrp;
+	struct kernfs_node *kn;
+	int ret, closid;
+
+	/* Only allow mkdir in the root directory */
+	if (parent_kn != rdtgroup_default.kn)
+		return -EPERM;
+
+	/* Do not accept '\n' to avoid unparsable situation. */
+	if (strchr(name, '\n'))
+		return -EINVAL;
+
+	parent = rdtgroup_kn_lock_live(parent_kn);
+	if (!parent) {
+		ret = -ENODEV;
+		goto out_unlock;
+	}
+
+	ret = closid_alloc();
+	if (ret < 0)
+		goto out_unlock;
+	closid = ret;
+
+	/* allocate the rdtgroup. */
+	rdtgrp = kzalloc(sizeof(*rdtgrp), GFP_KERNEL);
+	if (!rdtgrp) {
+		ret = -ENOSPC;
+		goto out_closid_free;
+	}
+	rdtgrp->closid = closid;
+	list_add(&rdtgrp->rdtgroup_list, &rdt_all_groups);
+
+	/* kernfs creates the directory for rdtgrp */
+	kn = kernfs_create_dir(parent->kn, name, mode, rdtgrp);
+	if (IS_ERR(kn)) {
+		ret = PTR_ERR(kn);
+		goto out_cancel_ref;
+	}
+	rdtgrp->kn = kn;
+
+	/*
+	 * kernfs_remove() will drop the reference count on "kn" which
+	 * will free it. But we still need it to stick around for the
+	 * rdtgroup_kn_unlock(kn} call below. Take one extra reference
+	 * here, which will be dropped inside rdtgroup_kn_unlock().
+	 */
+	kernfs_get(kn);
+
+	ret = rdtgroup_kn_set_ugid(kn);
+	if (ret)
+		goto out_destroy;
+
+	ret = rdtgroup_add_files(kn, rdtgroup_base_files,
+				 ARRAY_SIZE(rdtgroup_base_files));
+	if (ret)
+		goto out_destroy;
+
+	kernfs_activate(kn);
+
+	ret = 0;
+	goto out_unlock;
+
+out_destroy:
+	kernfs_remove(rdtgrp->kn);
+out_cancel_ref:
+	list_del(&rdtgrp->rdtgroup_list);
+	kfree(rdtgrp);
+out_closid_free:
+	closid_free(closid);
+out_unlock:
+	rdtgroup_kn_unlock(parent_kn);
+	return ret;
+}
+
+static int rdtgroup_rmdir(struct kernfs_node *kn)
+{
+	int ret, cpu, closid = rdtgroup_default.closid;
+	struct rdtgroup *rdtgrp;
+	cpumask_var_t tmpmask;
+
+	if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL))
+		return -ENOMEM;
+
+	rdtgrp = rdtgroup_kn_lock_live(kn);
+	if (!rdtgrp) {
+		ret = -EPERM;
+		goto out;
+	}
+
+	/* Give any tasks back to the default group */
+	rdt_move_group_tasks(rdtgrp, &rdtgroup_default, tmpmask);
+
+	/* Give any CPUs back to the default group */
+	cpumask_or(&rdtgroup_default.cpu_mask,
+		   &rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);
+
+	/* Update per cpu closid of the moved CPUs first */
+	for_each_cpu(cpu, &rdtgrp->cpu_mask)
+		per_cpu(cpu_closid, cpu) = closid;
+	/*
+	 * Update the MSR on moved CPUs and CPUs which have moved
+	 * task running on them.
+	 */
+	cpumask_or(tmpmask, tmpmask, &rdtgrp->cpu_mask);
+	rdt_update_closid(tmpmask, NULL);
+
+	rdtgrp->flags = RDT_DELETED;
+	closid_free(rdtgrp->closid);
+	list_del(&rdtgrp->rdtgroup_list);
+
+	/*
+	 * one extra hold on this, will drop when we kfree(rdtgrp)
+	 * in rdtgroup_kn_unlock()
+	 */
+	kernfs_get(kn);
+	kernfs_remove(rdtgrp->kn);
+	ret = 0;
+out:
+	rdtgroup_kn_unlock(kn);
+	free_cpumask_var(tmpmask);
+	return ret;
+}
+
+static int rdtgroup_show_options(struct seq_file *seq, struct kernfs_root *kf)
+{
+	if (rdt_resources_all[RDT_RESOURCE_L3DATA].enabled)
+		seq_puts(seq, ",cdp");
+	return 0;
+}
+
+static struct kernfs_syscall_ops rdtgroup_kf_syscall_ops = {
+	.mkdir		= rdtgroup_mkdir,
+	.rmdir		= rdtgroup_rmdir,
+	.show_options	= rdtgroup_show_options,
+};
+
+static int __init rdtgroup_setup_root(void)
+{
+	int ret;
+
+	rdt_root = kernfs_create_root(&rdtgroup_kf_syscall_ops,
+				      KERNFS_ROOT_CREATE_DEACTIVATED,
+				      &rdtgroup_default);
+	if (IS_ERR(rdt_root))
+		return PTR_ERR(rdt_root);
+
+	mutex_lock(&rdtgroup_mutex);
+
+	rdtgroup_default.closid = 0;
+	list_add(&rdtgroup_default.rdtgroup_list, &rdt_all_groups);
+
+	ret = rdtgroup_add_files(rdt_root->kn, rdtgroup_base_files,
+				 ARRAY_SIZE(rdtgroup_base_files));
+	if (ret) {
+		kernfs_destroy_root(rdt_root);
+		goto out;
+	}
+
+	rdtgroup_default.kn = rdt_root->kn;
+	kernfs_activate(rdtgroup_default.kn);
+
+out:
+	mutex_unlock(&rdtgroup_mutex);
+
+	return ret;
+}
+
+/*
+ * rdtgroup_init - rdtgroup initialization
+ *
+ * Setup resctrl file system including set up root, create mount point,
+ * register rdtgroup filesystem, and initialize files under root directory.
+ *
+ * Return: 0 on success or -errno
+ */
+int __init rdtgroup_init(void)
+{
+	int ret = 0;
+
+	ret = rdtgroup_setup_root();
+	if (ret)
+		return ret;
+
+	ret = sysfs_create_mount_point(fs_kobj, "resctrl");
+	if (ret)
+		goto cleanup_root;
+
+	ret = register_filesystem(&rdt_fs_type);
+	if (ret)
+		goto cleanup_mountpoint;
+
+	return 0;
+
+cleanup_mountpoint:
+	sysfs_remove_mount_point(fs_kobj, "resctrl");
+cleanup_root:
+	kernfs_destroy_root(rdt_root);
+
+	return ret;
+}