Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1534 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c b/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c
new file mode 100644
index 000000000..a999a58ca
--- /dev/null
+++ b/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c
@@ -0,0 +1,1534 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Resource Director Technology (RDT)
+ *
+ * Pseudo-locking support built on top of Cache Allocation Technology (CAT)
+ *
+ * Copyright (C) 2018 Intel Corporation
+ *
+ * Author: Reinette Chatre <reinette.chatre@intel.com>
+ */
+
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
+#include <linux/cacheinfo.h>
+#include <linux/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/debugfs.h>
+#include <linux/kthread.h>
+#include <linux/mman.h>
+#include <linux/pm_qos.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+
+#include <asm/cacheflush.h>
+#include <asm/intel-family.h>
+#include <asm/intel_rdt_sched.h>
+#include <asm/perf_event.h>
+
+#include "intel_rdt.h"
+
+#define CREATE_TRACE_POINTS
+#include "intel_rdt_pseudo_lock_event.h"
+
+/*
+ * MSR_MISC_FEATURE_CONTROL register enables the modification of hardware
+ * prefetcher state. Details about this register can be found in the MSR
+ * tables for specific platforms found in Intel's SDM.
+ */
+#define MSR_MISC_FEATURE_CONTROL	0x000001a4
+
+/*
+ * The bits needed to disable hardware prefetching varies based on the
+ * platform. During initialization we will discover which bits to use.
+ */
+static u64 prefetch_disable_bits;
+
+/*
+ * Major number assigned to and shared by all devices exposing
+ * pseudo-locked regions.
+ */
+static unsigned int pseudo_lock_major;
+static unsigned long pseudo_lock_minor_avail = GENMASK(MINORBITS, 0);
+static struct class *pseudo_lock_class;
+
+/**
+ * get_prefetch_disable_bits - prefetch disable bits of supported platforms
+ *
+ * Capture the list of platforms that have been validated to support
+ * pseudo-locking. This includes testing to ensure pseudo-locked regions
+ * with low cache miss rates can be created under variety of load conditions
+ * as well as that these pseudo-locked regions can maintain their low cache
+ * miss rates under variety of load conditions for significant lengths of time.
+ *
+ * After a platform has been validated to support pseudo-locking its
+ * hardware prefetch disable bits are included here as they are documented
+ * in the SDM.
+ *
+ * When adding a platform here also add support for its cache events to
+ * measure_cycles_perf_fn()
+ *
+ * Return:
+ * If platform is supported, the bits to disable hardware prefetchers, 0
+ * if platform is not supported.
+ */
+static u64 get_prefetch_disable_bits(void)
+{
+	if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL ||
+	    boot_cpu_data.x86 != 6)
+		return 0;
+
+	switch (boot_cpu_data.x86_model) {
+	case INTEL_FAM6_BROADWELL_X:
+		/*
+		 * SDM defines bits of MSR_MISC_FEATURE_CONTROL register
+		 * as:
+		 * 0    L2 Hardware Prefetcher Disable (R/W)
+		 * 1    L2 Adjacent Cache Line Prefetcher Disable (R/W)
+		 * 2    DCU Hardware Prefetcher Disable (R/W)
+		 * 3    DCU IP Prefetcher Disable (R/W)
+		 * 63:4 Reserved
+		 */
+		return 0xF;
+	case INTEL_FAM6_ATOM_GOLDMONT:
+	case INTEL_FAM6_ATOM_GOLDMONT_PLUS:
+		/*
+		 * SDM defines bits of MSR_MISC_FEATURE_CONTROL register
+		 * as:
+		 * 0     L2 Hardware Prefetcher Disable (R/W)
+		 * 1     Reserved
+		 * 2     DCU Hardware Prefetcher Disable (R/W)
+		 * 63:3  Reserved
+		 */
+		return 0x5;
+	}
+
+	return 0;
+}
+
+/*
+ * Helper to write 64bit value to MSR without tracing. Used when
+ * use of the cache should be restricted and use of registers used
+ * for local variables avoided.
+ */
+static inline void pseudo_wrmsrl_notrace(unsigned int msr, u64 val)
+{
+	__wrmsr(msr, (u32)(val & 0xffffffffULL), (u32)(val >> 32));
+}
+
+/**
+ * pseudo_lock_minor_get - Obtain available minor number
+ * @minor: Pointer to where new minor number will be stored
+ *
+ * A bitmask is used to track available minor numbers. Here the next free
+ * minor number is marked as unavailable and returned.
+ *
+ * Return: 0 on success, <0 on failure.
+ */
+static int pseudo_lock_minor_get(unsigned int *minor)
+{
+	unsigned long first_bit;
+
+	first_bit = find_first_bit(&pseudo_lock_minor_avail, MINORBITS);
+
+	if (first_bit == MINORBITS)
+		return -ENOSPC;
+
+	__clear_bit(first_bit, &pseudo_lock_minor_avail);
+	*minor = first_bit;
+
+	return 0;
+}
+
+/**
+ * pseudo_lock_minor_release - Return minor number to available
+ * @minor: The minor number made available
+ */
+static void pseudo_lock_minor_release(unsigned int minor)
+{
+	__set_bit(minor, &pseudo_lock_minor_avail);
+}
+
+/**
+ * region_find_by_minor - Locate a pseudo-lock region by inode minor number
+ * @minor: The minor number of the device representing pseudo-locked region
+ *
+ * When the character device is accessed we need to determine which
+ * pseudo-locked region it belongs to. This is done by matching the minor
+ * number of the device to the pseudo-locked region it belongs.
+ *
+ * Minor numbers are assigned at the time a pseudo-locked region is associated
+ * with a cache instance.
+ *
+ * Return: On success return pointer to resource group owning the pseudo-locked
+ *         region, NULL on failure.
+ */
+static struct rdtgroup *region_find_by_minor(unsigned int minor)
+{
+	struct rdtgroup *rdtgrp, *rdtgrp_match = NULL;
+
+	list_for_each_entry(rdtgrp, &rdt_all_groups, rdtgroup_list) {
+		if (rdtgrp->plr && rdtgrp->plr->minor == minor) {
+			rdtgrp_match = rdtgrp;
+			break;
+		}
+	}
+	return rdtgrp_match;
+}
+
+/**
+ * pseudo_lock_pm_req - A power management QoS request list entry
+ * @list:	Entry within the @pm_reqs list for a pseudo-locked region
+ * @req:	PM QoS request
+ */
+struct pseudo_lock_pm_req {
+	struct list_head list;
+	struct dev_pm_qos_request req;
+};
+
+static void pseudo_lock_cstates_relax(struct pseudo_lock_region *plr)
+{
+	struct pseudo_lock_pm_req *pm_req, *next;
+
+	list_for_each_entry_safe(pm_req, next, &plr->pm_reqs, list) {
+		dev_pm_qos_remove_request(&pm_req->req);
+		list_del(&pm_req->list);
+		kfree(pm_req);
+	}
+}
+
+/**
+ * pseudo_lock_cstates_constrain - Restrict cores from entering C6
+ *
+ * To prevent the cache from being affected by power management entering
+ * C6 has to be avoided. This is accomplished by requesting a latency
+ * requirement lower than lowest C6 exit latency of all supported
+ * platforms as found in the cpuidle state tables in the intel_idle driver.
+ * At this time it is possible to do so with a single latency requirement
+ * for all supported platforms.
+ *
+ * Since Goldmont is supported, which is affected by X86_BUG_MONITOR,
+ * the ACPI latencies need to be considered while keeping in mind that C2
+ * may be set to map to deeper sleep states. In this case the latency
+ * requirement needs to prevent entering C2 also.
+ */
+static int pseudo_lock_cstates_constrain(struct pseudo_lock_region *plr)
+{
+	struct pseudo_lock_pm_req *pm_req;
+	int cpu;
+	int ret;
+
+	for_each_cpu(cpu, &plr->d->cpu_mask) {
+		pm_req = kzalloc(sizeof(*pm_req), GFP_KERNEL);
+		if (!pm_req) {
+			rdt_last_cmd_puts("fail allocating mem for PM QoS\n");
+			ret = -ENOMEM;
+			goto out_err;
+		}
+		ret = dev_pm_qos_add_request(get_cpu_device(cpu),
+					     &pm_req->req,
+					     DEV_PM_QOS_RESUME_LATENCY,
+					     30);
+		if (ret < 0) {
+			rdt_last_cmd_printf("fail to add latency req cpu%d\n",
+					    cpu);
+			kfree(pm_req);
+			ret = -1;
+			goto out_err;
+		}
+		list_add(&pm_req->list, &plr->pm_reqs);
+	}
+
+	return 0;
+
+out_err:
+	pseudo_lock_cstates_relax(plr);
+	return ret;
+}
+
+/**
+ * pseudo_lock_region_clear - Reset pseudo-lock region data
+ * @plr: pseudo-lock region
+ *
+ * All content of the pseudo-locked region is reset - any memory allocated
+ * freed.
+ *
+ * Return: void
+ */
+static void pseudo_lock_region_clear(struct pseudo_lock_region *plr)
+{
+	plr->size = 0;
+	plr->line_size = 0;
+	kfree(plr->kmem);
+	plr->kmem = NULL;
+	plr->r = NULL;
+	if (plr->d)
+		plr->d->plr = NULL;
+	plr->d = NULL;
+	plr->cbm = 0;
+	plr->debugfs_dir = NULL;
+}
+
+/**
+ * pseudo_lock_region_init - Initialize pseudo-lock region information
+ * @plr: pseudo-lock region
+ *
+ * Called after user provided a schemata to be pseudo-locked. From the
+ * schemata the &struct pseudo_lock_region is on entry already initialized
+ * with the resource, domain, and capacity bitmask. Here the information
+ * required for pseudo-locking is deduced from this data and &struct
+ * pseudo_lock_region initialized further. This information includes:
+ * - size in bytes of the region to be pseudo-locked
+ * - cache line size to know the stride with which data needs to be accessed
+ *   to be pseudo-locked
+ * - a cpu associated with the cache instance on which the pseudo-locking
+ *   flow can be executed
+ *
+ * Return: 0 on success, <0 on failure. Descriptive error will be written
+ * to last_cmd_status buffer.
+ */
+static int pseudo_lock_region_init(struct pseudo_lock_region *plr)
+{
+	struct cpu_cacheinfo *ci;
+	int ret;
+	int i;
+
+	/* Pick the first cpu we find that is associated with the cache. */
+	plr->cpu = cpumask_first(&plr->d->cpu_mask);
+
+	if (!cpu_online(plr->cpu)) {
+		rdt_last_cmd_printf("cpu %u associated with cache not online\n",
+				    plr->cpu);
+		ret = -ENODEV;
+		goto out_region;
+	}
+
+	ci = get_cpu_cacheinfo(plr->cpu);
+
+	plr->size = rdtgroup_cbm_to_size(plr->r, plr->d, plr->cbm);
+
+	for (i = 0; i < ci->num_leaves; i++) {
+		if (ci->info_list[i].level == plr->r->cache_level) {
+			plr->line_size = ci->info_list[i].coherency_line_size;
+			return 0;
+		}
+	}
+
+	ret = -1;
+	rdt_last_cmd_puts("unable to determine cache line size\n");
+out_region:
+	pseudo_lock_region_clear(plr);
+	return ret;
+}
+
+/**
+ * pseudo_lock_init - Initialize a pseudo-lock region
+ * @rdtgrp: resource group to which new pseudo-locked region will belong
+ *
+ * A pseudo-locked region is associated with a resource group. When this
+ * association is created the pseudo-locked region is initialized. The
+ * details of the pseudo-locked region are not known at this time so only
+ * allocation is done and association established.
+ *
+ * Return: 0 on success, <0 on failure
+ */
+static int pseudo_lock_init(struct rdtgroup *rdtgrp)
+{
+	struct pseudo_lock_region *plr;
+
+	plr = kzalloc(sizeof(*plr), GFP_KERNEL);
+	if (!plr)
+		return -ENOMEM;
+
+	init_waitqueue_head(&plr->lock_thread_wq);
+	INIT_LIST_HEAD(&plr->pm_reqs);
+	rdtgrp->plr = plr;
+	return 0;
+}
+
+/**
+ * pseudo_lock_region_alloc - Allocate kernel memory that will be pseudo-locked
+ * @plr: pseudo-lock region
+ *
+ * Initialize the details required to set up the pseudo-locked region and
+ * allocate the contiguous memory that will be pseudo-locked to the cache.
+ *
+ * Return: 0 on success, <0 on failure.  Descriptive error will be written
+ * to last_cmd_status buffer.
+ */
+static int pseudo_lock_region_alloc(struct pseudo_lock_region *plr)
+{
+	int ret;
+
+	ret = pseudo_lock_region_init(plr);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * We do not yet support contiguous regions larger than
+	 * KMALLOC_MAX_SIZE.
+	 */
+	if (plr->size > KMALLOC_MAX_SIZE) {
+		rdt_last_cmd_puts("requested region exceeds maximum size\n");
+		ret = -E2BIG;
+		goto out_region;
+	}
+
+	plr->kmem = kzalloc(plr->size, GFP_KERNEL);
+	if (!plr->kmem) {
+		rdt_last_cmd_puts("unable to allocate memory\n");
+		ret = -ENOMEM;
+		goto out_region;
+	}
+
+	ret = 0;
+	goto out;
+out_region:
+	pseudo_lock_region_clear(plr);
+out:
+	return ret;
+}
+
+/**
+ * pseudo_lock_free - Free a pseudo-locked region
+ * @rdtgrp: resource group to which pseudo-locked region belonged
+ *
+ * The pseudo-locked region's resources have already been released, or not
+ * yet created at this point. Now it can be freed and disassociated from the
+ * resource group.
+ *
+ * Return: void
+ */
+static void pseudo_lock_free(struct rdtgroup *rdtgrp)
+{
+	pseudo_lock_region_clear(rdtgrp->plr);
+	kfree(rdtgrp->plr);
+	rdtgrp->plr = NULL;
+}
+
+/**
+ * pseudo_lock_fn - Load kernel memory into cache
+ * @_rdtgrp: resource group to which pseudo-lock region belongs
+ *
+ * This is the core pseudo-locking flow.
+ *
+ * First we ensure that the kernel memory cannot be found in the cache.
+ * Then, while taking care that there will be as little interference as
+ * possible, the memory to be loaded is accessed while core is running
+ * with class of service set to the bitmask of the pseudo-locked region.
+ * After this is complete no future CAT allocations will be allowed to
+ * overlap with this bitmask.
+ *
+ * Local register variables are utilized to ensure that the memory region
+ * to be locked is the only memory access made during the critical locking
+ * loop.
+ *
+ * Return: 0. Waiter on waitqueue will be woken on completion.
+ */
+static int pseudo_lock_fn(void *_rdtgrp)
+{
+	struct rdtgroup *rdtgrp = _rdtgrp;
+	struct pseudo_lock_region *plr = rdtgrp->plr;
+	u32 rmid_p, closid_p;
+	unsigned long i;
+#ifdef CONFIG_KASAN
+	/*
+	 * The registers used for local register variables are also used
+	 * when KASAN is active. When KASAN is active we use a regular
+	 * variable to ensure we always use a valid pointer, but the cost
+	 * is that this variable will enter the cache through evicting the
+	 * memory we are trying to lock into the cache. Thus expect lower
+	 * pseudo-locking success rate when KASAN is active.
+	 */
+	unsigned int line_size;
+	unsigned int size;
+	void *mem_r;
+#else
+	register unsigned int line_size asm("esi");
+	register unsigned int size asm("edi");
+#ifdef CONFIG_X86_64
+	register void *mem_r asm("rbx");
+#else
+	register void *mem_r asm("ebx");
+#endif /* CONFIG_X86_64 */
+#endif /* CONFIG_KASAN */
+
+	/*
+	 * Make sure none of the allocated memory is cached. If it is we
+	 * will get a cache hit in below loop from outside of pseudo-locked
+	 * region.
+	 * wbinvd (as opposed to clflush/clflushopt) is required to
+	 * increase likelihood that allocated cache portion will be filled
+	 * with associated memory.
+	 */
+	native_wbinvd();
+
+	/*
+	 * Always called with interrupts enabled. By disabling interrupts
+	 * ensure that we will not be preempted during this critical section.
+	 */
+	local_irq_disable();
+
+	/*
+	 * Call wrmsr and rdmsr as directly as possible to avoid tracing
+	 * clobbering local register variables or affecting cache accesses.
+	 *
+	 * Disable the hardware prefetcher so that when the end of the memory
+	 * being pseudo-locked is reached the hardware will not read beyond
+	 * the buffer and evict pseudo-locked memory read earlier from the
+	 * cache.
+	 */
+	__wrmsr(MSR_MISC_FEATURE_CONTROL, prefetch_disable_bits, 0x0);
+	closid_p = this_cpu_read(pqr_state.cur_closid);
+	rmid_p = this_cpu_read(pqr_state.cur_rmid);
+	mem_r = plr->kmem;
+	size = plr->size;
+	line_size = plr->line_size;
+	/*
+	 * Critical section begin: start by writing the closid associated
+	 * with the capacity bitmask of the cache region being
+	 * pseudo-locked followed by reading of kernel memory to load it
+	 * into the cache.
+	 */
+	__wrmsr(IA32_PQR_ASSOC, rmid_p, rdtgrp->closid);
+	/*
+	 * Cache was flushed earlier. Now access kernel memory to read it
+	 * into cache region associated with just activated plr->closid.
+	 * Loop over data twice:
+	 * - In first loop the cache region is shared with the page walker
+	 *   as it populates the paging structure caches (including TLB).
+	 * - In the second loop the paging structure caches are used and
+	 *   cache region is populated with the memory being referenced.
+	 */
+	for (i = 0; i < size; i += PAGE_SIZE) {
+		/*
+		 * Add a barrier to prevent speculative execution of this
+		 * loop reading beyond the end of the buffer.
+		 */
+		rmb();
+		asm volatile("mov (%0,%1,1), %%eax\n\t"
+			:
+			: "r" (mem_r), "r" (i)
+			: "%eax", "memory");
+	}
+	for (i = 0; i < size; i += line_size) {
+		/*
+		 * Add a barrier to prevent speculative execution of this
+		 * loop reading beyond the end of the buffer.
+		 */
+		rmb();
+		asm volatile("mov (%0,%1,1), %%eax\n\t"
+			:
+			: "r" (mem_r), "r" (i)
+			: "%eax", "memory");
+	}
+	/*
+	 * Critical section end: restore closid with capacity bitmask that
+	 * does not overlap with pseudo-locked region.
+	 */
+	__wrmsr(IA32_PQR_ASSOC, rmid_p, closid_p);
+
+	/* Re-enable the hardware prefetcher(s) */
+	wrmsr(MSR_MISC_FEATURE_CONTROL, 0x0, 0x0);
+	local_irq_enable();
+
+	plr->thread_done = 1;
+	wake_up_interruptible(&plr->lock_thread_wq);
+	return 0;
+}
+
+/**
+ * rdtgroup_monitor_in_progress - Test if monitoring in progress
+ * @r: resource group being queried
+ *
+ * Return: 1 if monitor groups have been created for this resource
+ * group, 0 otherwise.
+ */
+static int rdtgroup_monitor_in_progress(struct rdtgroup *rdtgrp)
+{
+	return !list_empty(&rdtgrp->mon.crdtgrp_list);
+}
+
+/**
+ * rdtgroup_locksetup_user_restrict - Restrict user access to group
+ * @rdtgrp: resource group needing access restricted
+ *
+ * A resource group used for cache pseudo-locking cannot have cpus or tasks
+ * assigned to it. This is communicated to the user by restricting access
+ * to all the files that can be used to make such changes.
+ *
+ * Permissions restored with rdtgroup_locksetup_user_restore()
+ *
+ * Return: 0 on success, <0 on failure. If a failure occurs during the
+ * restriction of access an attempt will be made to restore permissions but
+ * the state of the mode of these files will be uncertain when a failure
+ * occurs.
+ */
+static int rdtgroup_locksetup_user_restrict(struct rdtgroup *rdtgrp)
+{
+	int ret;
+
+	ret = rdtgroup_kn_mode_restrict(rdtgrp, "tasks");
+	if (ret)
+		return ret;
+
+	ret = rdtgroup_kn_mode_restrict(rdtgrp, "cpus");
+	if (ret)
+		goto err_tasks;
+
+	ret = rdtgroup_kn_mode_restrict(rdtgrp, "cpus_list");
+	if (ret)
+		goto err_cpus;
+
+	if (rdt_mon_capable) {
+		ret = rdtgroup_kn_mode_restrict(rdtgrp, "mon_groups");
+		if (ret)
+			goto err_cpus_list;
+	}
+
+	ret = 0;
+	goto out;
+
+err_cpus_list:
+	rdtgroup_kn_mode_restore(rdtgrp, "cpus_list", 0777);
+err_cpus:
+	rdtgroup_kn_mode_restore(rdtgrp, "cpus", 0777);
+err_tasks:
+	rdtgroup_kn_mode_restore(rdtgrp, "tasks", 0777);
+out:
+	return ret;
+}
+
+/**
+ * rdtgroup_locksetup_user_restore - Restore user access to group
+ * @rdtgrp: resource group needing access restored
+ *
+ * Restore all file access previously removed using
+ * rdtgroup_locksetup_user_restrict()
+ *
+ * Return: 0 on success, <0 on failure.  If a failure occurs during the
+ * restoration of access an attempt will be made to restrict permissions
+ * again but the state of the mode of these files will be uncertain when
+ * a failure occurs.
+ */
+static int rdtgroup_locksetup_user_restore(struct rdtgroup *rdtgrp)
+{
+	int ret;
+
+	ret = rdtgroup_kn_mode_restore(rdtgrp, "tasks", 0777);
+	if (ret)
+		return ret;
+
+	ret = rdtgroup_kn_mode_restore(rdtgrp, "cpus", 0777);
+	if (ret)
+		goto err_tasks;
+
+	ret = rdtgroup_kn_mode_restore(rdtgrp, "cpus_list", 0777);
+	if (ret)
+		goto err_cpus;
+
+	if (rdt_mon_capable) {
+		ret = rdtgroup_kn_mode_restore(rdtgrp, "mon_groups", 0777);
+		if (ret)
+			goto err_cpus_list;
+	}
+
+	ret = 0;
+	goto out;
+
+err_cpus_list:
+	rdtgroup_kn_mode_restrict(rdtgrp, "cpus_list");
+err_cpus:
+	rdtgroup_kn_mode_restrict(rdtgrp, "cpus");
+err_tasks:
+	rdtgroup_kn_mode_restrict(rdtgrp, "tasks");
+out:
+	return ret;
+}
+
+/**
+ * rdtgroup_locksetup_enter - Resource group enters locksetup mode
+ * @rdtgrp: resource group requested to enter locksetup mode
+ *
+ * A resource group enters locksetup mode to reflect that it would be used
+ * to represent a pseudo-locked region and is in the process of being set
+ * up to do so. A resource group used for a pseudo-locked region would
+ * lose the closid associated with it so we cannot allow it to have any
+ * tasks or cpus assigned nor permit tasks or cpus to be assigned in the
+ * future. Monitoring of a pseudo-locked region is not allowed either.
+ *
+ * The above and more restrictions on a pseudo-locked region are checked
+ * for and enforced before the resource group enters the locksetup mode.
+ *
+ * Returns: 0 if the resource group successfully entered locksetup mode, <0
+ * on failure. On failure the last_cmd_status buffer is updated with text to
+ * communicate details of failure to the user.
+ */
+int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp)
+{
+	int ret;
+
+	/*
+	 * The default resource group can neither be removed nor lose the
+	 * default closid associated with it.
+	 */
+	if (rdtgrp == &rdtgroup_default) {
+		rdt_last_cmd_puts("cannot pseudo-lock default group\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Cache Pseudo-locking not supported when CDP is enabled.
+	 *
+	 * Some things to consider if you would like to enable this
+	 * support (using L3 CDP as example):
+	 * - When CDP is enabled two separate resources are exposed,
+	 *   L3DATA and L3CODE, but they are actually on the same cache.
+	 *   The implication for pseudo-locking is that if a
+	 *   pseudo-locked region is created on a domain of one
+	 *   resource (eg. L3CODE), then a pseudo-locked region cannot
+	 *   be created on that same domain of the other resource
+	 *   (eg. L3DATA). This is because the creation of a
+	 *   pseudo-locked region involves a call to wbinvd that will
+	 *   affect all cache allocations on particular domain.
+	 * - Considering the previous, it may be possible to only
+	 *   expose one of the CDP resources to pseudo-locking and
+	 *   hide the other. For example, we could consider to only
+	 *   expose L3DATA and since the L3 cache is unified it is
+	 *   still possible to place instructions there are execute it.
+	 * - If only one region is exposed to pseudo-locking we should
+	 *   still keep in mind that availability of a portion of cache
+	 *   for pseudo-locking should take into account both resources.
+	 *   Similarly, if a pseudo-locked region is created in one
+	 *   resource, the portion of cache used by it should be made
+	 *   unavailable to all future allocations from both resources.
+	 */
+	if (rdt_resources_all[RDT_RESOURCE_L3DATA].alloc_enabled ||
+	    rdt_resources_all[RDT_RESOURCE_L2DATA].alloc_enabled) {
+		rdt_last_cmd_puts("CDP enabled\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Not knowing the bits to disable prefetching implies that this
+	 * platform does not support Cache Pseudo-Locking.
+	 */
+	prefetch_disable_bits = get_prefetch_disable_bits();
+	if (prefetch_disable_bits == 0) {
+		rdt_last_cmd_puts("pseudo-locking not supported\n");
+		return -EINVAL;
+	}
+
+	if (rdtgroup_monitor_in_progress(rdtgrp)) {
+		rdt_last_cmd_puts("monitoring in progress\n");
+		return -EINVAL;
+	}
+
+	if (rdtgroup_tasks_assigned(rdtgrp)) {
+		rdt_last_cmd_puts("tasks assigned to resource group\n");
+		return -EINVAL;
+	}
+
+	if (!cpumask_empty(&rdtgrp->cpu_mask)) {
+		rdt_last_cmd_puts("CPUs assigned to resource group\n");
+		return -EINVAL;
+	}
+
+	if (rdtgroup_locksetup_user_restrict(rdtgrp)) {
+		rdt_last_cmd_puts("unable to modify resctrl permissions\n");
+		return -EIO;
+	}
+
+	ret = pseudo_lock_init(rdtgrp);
+	if (ret) {
+		rdt_last_cmd_puts("unable to init pseudo-lock region\n");
+		goto out_release;
+	}
+
+	/*
+	 * If this system is capable of monitoring a rmid would have been
+	 * allocated when the control group was created. This is not needed
+	 * anymore when this group would be used for pseudo-locking. This
+	 * is safe to call on platforms not capable of monitoring.
+	 */
+	free_rmid(rdtgrp->mon.rmid);
+
+	ret = 0;
+	goto out;
+
+out_release:
+	rdtgroup_locksetup_user_restore(rdtgrp);
+out:
+	return ret;
+}
+
+/**
+ * rdtgroup_locksetup_exit - resource group exist locksetup mode
+ * @rdtgrp: resource group
+ *
+ * When a resource group exits locksetup mode the earlier restrictions are
+ * lifted.
+ *
+ * Return: 0 on success, <0 on failure
+ */
+int rdtgroup_locksetup_exit(struct rdtgroup *rdtgrp)
+{
+	int ret;
+
+	if (rdt_mon_capable) {
+		ret = alloc_rmid();
+		if (ret < 0) {
+			rdt_last_cmd_puts("out of RMIDs\n");
+			return ret;
+		}
+		rdtgrp->mon.rmid = ret;
+	}
+
+	ret = rdtgroup_locksetup_user_restore(rdtgrp);
+	if (ret) {
+		free_rmid(rdtgrp->mon.rmid);
+		return ret;
+	}
+
+	pseudo_lock_free(rdtgrp);
+	return 0;
+}
+
+/**
+ * rdtgroup_cbm_overlaps_pseudo_locked - Test if CBM or portion is pseudo-locked
+ * @d: RDT domain
+ * @cbm: CBM to test
+ *
+ * @d represents a cache instance and @cbm a capacity bitmask that is
+ * considered for it. Determine if @cbm overlaps with any existing
+ * pseudo-locked region on @d.
+ *
+ * @cbm is unsigned long, even if only 32 bits are used, to make the
+ * bitmap functions work correctly.
+ *
+ * Return: true if @cbm overlaps with pseudo-locked region on @d, false
+ * otherwise.
+ */
+bool rdtgroup_cbm_overlaps_pseudo_locked(struct rdt_domain *d, unsigned long cbm)
+{
+	unsigned int cbm_len;
+	unsigned long cbm_b;
+
+	if (d->plr) {
+		cbm_len = d->plr->r->cache.cbm_len;
+		cbm_b = d->plr->cbm;
+		if (bitmap_intersects(&cbm, &cbm_b, cbm_len))
+			return true;
+	}
+	return false;
+}
+
+/**
+ * rdtgroup_pseudo_locked_in_hierarchy - Pseudo-locked region in cache hierarchy
+ * @d: RDT domain under test
+ *
+ * The setup of a pseudo-locked region affects all cache instances within
+ * the hierarchy of the region. It is thus essential to know if any
+ * pseudo-locked regions exist within a cache hierarchy to prevent any
+ * attempts to create new pseudo-locked regions in the same hierarchy.
+ *
+ * Return: true if a pseudo-locked region exists in the hierarchy of @d or
+ *         if it is not possible to test due to memory allocation issue,
+ *         false otherwise.
+ */
+bool rdtgroup_pseudo_locked_in_hierarchy(struct rdt_domain *d)
+{
+	cpumask_var_t cpu_with_psl;
+	struct rdt_resource *r;
+	struct rdt_domain *d_i;
+	bool ret = false;
+
+	if (!zalloc_cpumask_var(&cpu_with_psl, GFP_KERNEL))
+		return true;
+
+	/*
+	 * First determine which cpus have pseudo-locked regions
+	 * associated with them.
+	 */
+	for_each_alloc_enabled_rdt_resource(r) {
+		list_for_each_entry(d_i, &r->domains, list) {
+			if (d_i->plr)
+				cpumask_or(cpu_with_psl, cpu_with_psl,
+					   &d_i->cpu_mask);
+		}
+	}
+
+	/*
+	 * Next test if new pseudo-locked region would intersect with
+	 * existing region.
+	 */
+	if (cpumask_intersects(&d->cpu_mask, cpu_with_psl))
+		ret = true;
+
+	free_cpumask_var(cpu_with_psl);
+	return ret;
+}
+
+/**
+ * measure_cycles_lat_fn - Measure cycle latency to read pseudo-locked memory
+ * @_plr: pseudo-lock region to measure
+ *
+ * There is no deterministic way to test if a memory region is cached. One
+ * way is to measure how long it takes to read the memory, the speed of
+ * access is a good way to learn how close to the cpu the data was. Even
+ * more, if the prefetcher is disabled and the memory is read at a stride
+ * of half the cache line, then a cache miss will be easy to spot since the
+ * read of the first half would be significantly slower than the read of
+ * the second half.
+ *
+ * Return: 0. Waiter on waitqueue will be woken on completion.
+ */
+static int measure_cycles_lat_fn(void *_plr)
+{
+	struct pseudo_lock_region *plr = _plr;
+	unsigned long i;
+	u64 start, end;
+#ifdef CONFIG_KASAN
+	/*
+	 * The registers used for local register variables are also used
+	 * when KASAN is active. When KASAN is active we use a regular
+	 * variable to ensure we always use a valid pointer to access memory.
+	 * The cost is that accessing this pointer, which could be in
+	 * cache, will be included in the measurement of memory read latency.
+	 */
+	void *mem_r;
+#else
+#ifdef CONFIG_X86_64
+	register void *mem_r asm("rbx");
+#else
+	register void *mem_r asm("ebx");
+#endif /* CONFIG_X86_64 */
+#endif /* CONFIG_KASAN */
+
+	local_irq_disable();
+	/*
+	 * The wrmsr call may be reordered with the assignment below it.
+	 * Call wrmsr as directly as possible to avoid tracing clobbering
+	 * local register variable used for memory pointer.
+	 */
+	__wrmsr(MSR_MISC_FEATURE_CONTROL, prefetch_disable_bits, 0x0);
+	mem_r = plr->kmem;
+	/*
+	 * Dummy execute of the time measurement to load the needed
+	 * instructions into the L1 instruction cache.
+	 */
+	start = rdtsc_ordered();
+	for (i = 0; i < plr->size; i += 32) {
+		start = rdtsc_ordered();
+		asm volatile("mov (%0,%1,1), %%eax\n\t"
+			     :
+			     : "r" (mem_r), "r" (i)
+			     : "%eax", "memory");
+		end = rdtsc_ordered();
+		trace_pseudo_lock_mem_latency((u32)(end - start));
+	}
+	wrmsr(MSR_MISC_FEATURE_CONTROL, 0x0, 0x0);
+	local_irq_enable();
+	plr->thread_done = 1;
+	wake_up_interruptible(&plr->lock_thread_wq);
+	return 0;
+}
+
+static int measure_cycles_perf_fn(void *_plr)
+{
+	unsigned long long l3_hits = 0, l3_miss = 0;
+	u64 l3_hit_bits = 0, l3_miss_bits = 0;
+	struct pseudo_lock_region *plr = _plr;
+	unsigned long long l2_hits, l2_miss;
+	u64 l2_hit_bits, l2_miss_bits;
+	unsigned long i;
+#ifdef CONFIG_KASAN
+	/*
+	 * The registers used for local register variables are also used
+	 * when KASAN is active. When KASAN is active we use regular variables
+	 * at the cost of including cache access latency to these variables
+	 * in the measurements.
+	 */
+	unsigned int line_size;
+	unsigned int size;
+	void *mem_r;
+#else
+	register unsigned int line_size asm("esi");
+	register unsigned int size asm("edi");
+#ifdef CONFIG_X86_64
+	register void *mem_r asm("rbx");
+#else
+	register void *mem_r asm("ebx");
+#endif /* CONFIG_X86_64 */
+#endif /* CONFIG_KASAN */
+
+	/*
+	 * Non-architectural event for the Goldmont Microarchitecture
+	 * from Intel x86 Architecture Software Developer Manual (SDM):
+	 * MEM_LOAD_UOPS_RETIRED D1H (event number)
+	 * Umask values:
+	 *     L1_HIT   01H
+	 *     L2_HIT   02H
+	 *     L1_MISS  08H
+	 *     L2_MISS  10H
+	 *
+	 * On Broadwell Microarchitecture the MEM_LOAD_UOPS_RETIRED event
+	 * has two "no fix" errata associated with it: BDM35 and BDM100. On
+	 * this platform we use the following events instead:
+	 *  L2_RQSTS 24H (Documented in https://download.01.org/perfmon/BDW/)
+	 *       REFERENCES FFH
+	 *       MISS       3FH
+	 *  LONGEST_LAT_CACHE 2EH (Documented in SDM)
+	 *       REFERENCE 4FH
+	 *       MISS      41H
+	 */
+
+	/*
+	 * Start by setting flags for IA32_PERFEVTSELx:
+	 *     OS  (Operating system mode)  0x2
+	 *     INT (APIC interrupt enable)  0x10
+	 *     EN  (Enable counter)         0x40
+	 *
+	 * Then add the Umask value and event number to select performance
+	 * event.
+	 */
+
+	switch (boot_cpu_data.x86_model) {
+	case INTEL_FAM6_ATOM_GOLDMONT:
+	case INTEL_FAM6_ATOM_GOLDMONT_PLUS:
+		l2_hit_bits = (0x52ULL << 16) | (0x2 << 8) | 0xd1;
+		l2_miss_bits = (0x52ULL << 16) | (0x10 << 8) | 0xd1;
+		break;
+	case INTEL_FAM6_BROADWELL_X:
+		/* On BDW the l2_hit_bits count references, not hits */
+		l2_hit_bits = (0x52ULL << 16) | (0xff << 8) | 0x24;
+		l2_miss_bits = (0x52ULL << 16) | (0x3f << 8) | 0x24;
+		/* On BDW the l3_hit_bits count references, not hits */
+		l3_hit_bits = (0x52ULL << 16) | (0x4f << 8) | 0x2e;
+		l3_miss_bits = (0x52ULL << 16) | (0x41 << 8) | 0x2e;
+		break;
+	default:
+		goto out;
+	}
+
+	local_irq_disable();
+	/*
+	 * Call wrmsr direcly to avoid the local register variables from
+	 * being overwritten due to reordering of their assignment with
+	 * the wrmsr calls.
+	 */
+	__wrmsr(MSR_MISC_FEATURE_CONTROL, prefetch_disable_bits, 0x0);
+	/* Disable events and reset counters */
+	pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0, 0x0);
+	pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 1, 0x0);
+	pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_PERFCTR0, 0x0);
+	pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_PERFCTR0 + 1, 0x0);
+	if (l3_hit_bits > 0) {
+		pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 2, 0x0);
+		pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 3, 0x0);
+		pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_PERFCTR0 + 2, 0x0);
+		pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_PERFCTR0 + 3, 0x0);
+	}
+	/* Set and enable the L2 counters */
+	pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0, l2_hit_bits);
+	pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 1, l2_miss_bits);
+	if (l3_hit_bits > 0) {
+		pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 2,
+				      l3_hit_bits);
+		pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 3,
+				      l3_miss_bits);
+	}
+	mem_r = plr->kmem;
+	size = plr->size;
+	line_size = plr->line_size;
+	for (i = 0; i < size; i += line_size) {
+		asm volatile("mov (%0,%1,1), %%eax\n\t"
+			     :
+			     : "r" (mem_r), "r" (i)
+			     : "%eax", "memory");
+	}
+	/*
+	 * Call wrmsr directly (no tracing) to not influence
+	 * the cache access counters as they are disabled.
+	 */
+	pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0,
+			      l2_hit_bits & ~(0x40ULL << 16));
+	pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 1,
+			      l2_miss_bits & ~(0x40ULL << 16));
+	if (l3_hit_bits > 0) {
+		pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 2,
+				      l3_hit_bits & ~(0x40ULL << 16));
+		pseudo_wrmsrl_notrace(MSR_ARCH_PERFMON_EVENTSEL0 + 3,
+				      l3_miss_bits & ~(0x40ULL << 16));
+	}
+	l2_hits = native_read_pmc(0);
+	l2_miss = native_read_pmc(1);
+	if (l3_hit_bits > 0) {
+		l3_hits = native_read_pmc(2);
+		l3_miss = native_read_pmc(3);
+	}
+	wrmsr(MSR_MISC_FEATURE_CONTROL, 0x0, 0x0);
+	local_irq_enable();
+	/*
+	 * On BDW we count references and misses, need to adjust. Sometimes
+	 * the "hits" counter is a bit more than the references, for
+	 * example, x references but x + 1 hits. To not report invalid
+	 * hit values in this case we treat that as misses eaqual to
+	 * references.
+	 */
+	if (boot_cpu_data.x86_model == INTEL_FAM6_BROADWELL_X)
+		l2_hits -= (l2_miss > l2_hits ? l2_hits : l2_miss);
+	trace_pseudo_lock_l2(l2_hits, l2_miss);
+	if (l3_hit_bits > 0) {
+		if (boot_cpu_data.x86_model == INTEL_FAM6_BROADWELL_X)
+			l3_hits -= (l3_miss > l3_hits ? l3_hits : l3_miss);
+		trace_pseudo_lock_l3(l3_hits, l3_miss);
+	}
+
+out:
+	plr->thread_done = 1;
+	wake_up_interruptible(&plr->lock_thread_wq);
+	return 0;
+}
+
+/**
+ * pseudo_lock_measure_cycles - Trigger latency measure to pseudo-locked region
+ *
+ * The measurement of latency to access a pseudo-locked region should be
+ * done from a cpu that is associated with that pseudo-locked region.
+ * Determine which cpu is associated with this region and start a thread on
+ * that cpu to perform the measurement, wait for that thread to complete.
+ *
+ * Return: 0 on success, <0 on failure
+ */
+static int pseudo_lock_measure_cycles(struct rdtgroup *rdtgrp, int sel)
+{
+	struct pseudo_lock_region *plr = rdtgrp->plr;
+	struct task_struct *thread;
+	unsigned int cpu;
+	int ret = -1;
+
+	cpus_read_lock();
+	mutex_lock(&rdtgroup_mutex);
+
+	if (rdtgrp->flags & RDT_DELETED) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	if (!plr->d) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	plr->thread_done = 0;
+	cpu = cpumask_first(&plr->d->cpu_mask);
+	if (!cpu_online(cpu)) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	if (sel == 1)
+		thread = kthread_create_on_node(measure_cycles_lat_fn, plr,
+						cpu_to_node(cpu),
+						"pseudo_lock_measure/%u",
+						cpu);
+	else if (sel == 2)
+		thread = kthread_create_on_node(measure_cycles_perf_fn, plr,
+						cpu_to_node(cpu),
+						"pseudo_lock_measure/%u",
+						cpu);
+	else
+		goto out;
+
+	if (IS_ERR(thread)) {
+		ret = PTR_ERR(thread);
+		goto out;
+	}
+	kthread_bind(thread, cpu);
+	wake_up_process(thread);
+
+	ret = wait_event_interruptible(plr->lock_thread_wq,
+				       plr->thread_done == 1);
+	if (ret < 0)
+		goto out;
+
+	ret = 0;
+
+out:
+	mutex_unlock(&rdtgroup_mutex);
+	cpus_read_unlock();
+	return ret;
+}
+
+static ssize_t pseudo_lock_measure_trigger(struct file *file,
+					   const char __user *user_buf,
+					   size_t count, loff_t *ppos)
+{
+	struct rdtgroup *rdtgrp = file->private_data;
+	size_t buf_size;
+	char buf[32];
+	int ret;
+	int sel;
+
+	buf_size = min(count, (sizeof(buf) - 1));
+	if (copy_from_user(buf, user_buf, buf_size))
+		return -EFAULT;
+
+	buf[buf_size] = '\0';
+	ret = kstrtoint(buf, 10, &sel);
+	if (ret == 0) {
+		if (sel != 1)
+			return -EINVAL;
+		ret = debugfs_file_get(file->f_path.dentry);
+		if (ret)
+			return ret;
+		ret = pseudo_lock_measure_cycles(rdtgrp, sel);
+		if (ret == 0)
+			ret = count;
+		debugfs_file_put(file->f_path.dentry);
+	}
+
+	return ret;
+}
+
+static const struct file_operations pseudo_measure_fops = {
+	.write = pseudo_lock_measure_trigger,
+	.open = simple_open,
+	.llseek = default_llseek,
+};
+
+/**
+ * rdtgroup_pseudo_lock_create - Create a pseudo-locked region
+ * @rdtgrp: resource group to which pseudo-lock region belongs
+ *
+ * Called when a resource group in the pseudo-locksetup mode receives a
+ * valid schemata that should be pseudo-locked. Since the resource group is
+ * in pseudo-locksetup mode the &struct pseudo_lock_region has already been
+ * allocated and initialized with the essential information. If a failure
+ * occurs the resource group remains in the pseudo-locksetup mode with the
+ * &struct pseudo_lock_region associated with it, but cleared from all
+ * information and ready for the user to re-attempt pseudo-locking by
+ * writing the schemata again.
+ *
+ * Return: 0 if the pseudo-locked region was successfully pseudo-locked, <0
+ * on failure. Descriptive error will be written to last_cmd_status buffer.
+ */
+int rdtgroup_pseudo_lock_create(struct rdtgroup *rdtgrp)
+{
+	struct pseudo_lock_region *plr = rdtgrp->plr;
+	struct task_struct *thread;
+	unsigned int new_minor;
+	struct device *dev;
+	int ret;
+
+	ret = pseudo_lock_region_alloc(plr);
+	if (ret < 0)
+		return ret;
+
+	ret = pseudo_lock_cstates_constrain(plr);
+	if (ret < 0) {
+		ret = -EINVAL;
+		goto out_region;
+	}
+
+	plr->thread_done = 0;
+
+	thread = kthread_create_on_node(pseudo_lock_fn, rdtgrp,
+					cpu_to_node(plr->cpu),
+					"pseudo_lock/%u", plr->cpu);
+	if (IS_ERR(thread)) {
+		ret = PTR_ERR(thread);
+		rdt_last_cmd_printf("locking thread returned error %d\n", ret);
+		goto out_cstates;
+	}
+
+	kthread_bind(thread, plr->cpu);
+	wake_up_process(thread);
+
+	ret = wait_event_interruptible(plr->lock_thread_wq,
+				       plr->thread_done == 1);
+	if (ret < 0) {
+		/*
+		 * If the thread does not get on the CPU for whatever
+		 * reason and the process which sets up the region is
+		 * interrupted then this will leave the thread in runnable
+		 * state and once it gets on the CPU it will derefence
+		 * the cleared, but not freed, plr struct resulting in an
+		 * empty pseudo-locking loop.
+		 */
+		rdt_last_cmd_puts("locking thread interrupted\n");
+		goto out_cstates;
+	}
+
+	ret = pseudo_lock_minor_get(&new_minor);
+	if (ret < 0) {
+		rdt_last_cmd_puts("unable to obtain a new minor number\n");
+		goto out_cstates;
+	}
+
+	/*
+	 * Unlock access but do not release the reference. The
+	 * pseudo-locked region will still be here on return.
+	 *
+	 * The mutex has to be released temporarily to avoid a potential
+	 * deadlock with the mm->mmap_sem semaphore which is obtained in
+	 * the device_create() and debugfs_create_dir() callpath below
+	 * as well as before the mmap() callback is called.
+	 */
+	mutex_unlock(&rdtgroup_mutex);
+
+	if (!IS_ERR_OR_NULL(debugfs_resctrl)) {
+		plr->debugfs_dir = debugfs_create_dir(rdtgrp->kn->name,
+						      debugfs_resctrl);
+		if (!IS_ERR_OR_NULL(plr->debugfs_dir))
+			debugfs_create_file("pseudo_lock_measure", 0200,
+					    plr->debugfs_dir, rdtgrp,
+					    &pseudo_measure_fops);
+	}
+
+	dev = device_create(pseudo_lock_class, NULL,
+			    MKDEV(pseudo_lock_major, new_minor),
+			    rdtgrp, "%s", rdtgrp->kn->name);
+
+	mutex_lock(&rdtgroup_mutex);
+
+	if (IS_ERR(dev)) {
+		ret = PTR_ERR(dev);
+		rdt_last_cmd_printf("failed to create character device: %d\n",
+				    ret);
+		goto out_debugfs;
+	}
+
+	/* We released the mutex - check if group was removed while we did so */
+	if (rdtgrp->flags & RDT_DELETED) {
+		ret = -ENODEV;
+		goto out_device;
+	}
+
+	plr->minor = new_minor;
+
+	rdtgrp->mode = RDT_MODE_PSEUDO_LOCKED;
+	closid_free(rdtgrp->closid);
+	rdtgroup_kn_mode_restore(rdtgrp, "cpus", 0444);
+	rdtgroup_kn_mode_restore(rdtgrp, "cpus_list", 0444);
+
+	ret = 0;
+	goto out;
+
+out_device:
+	device_destroy(pseudo_lock_class, MKDEV(pseudo_lock_major, new_minor));
+out_debugfs:
+	debugfs_remove_recursive(plr->debugfs_dir);
+	pseudo_lock_minor_release(new_minor);
+out_cstates:
+	pseudo_lock_cstates_relax(plr);
+out_region:
+	pseudo_lock_region_clear(plr);
+out:
+	return ret;
+}
+
+/**
+ * rdtgroup_pseudo_lock_remove - Remove a pseudo-locked region
+ * @rdtgrp: resource group to which the pseudo-locked region belongs
+ *
+ * The removal of a pseudo-locked region can be initiated when the resource
+ * group is removed from user space via a "rmdir" from userspace or the
+ * unmount of the resctrl filesystem. On removal the resource group does
+ * not go back to pseudo-locksetup mode before it is removed, instead it is
+ * removed directly. There is thus assymmetry with the creation where the
+ * &struct pseudo_lock_region is removed here while it was not created in
+ * rdtgroup_pseudo_lock_create().
+ *
+ * Return: void
+ */
+void rdtgroup_pseudo_lock_remove(struct rdtgroup *rdtgrp)
+{
+	struct pseudo_lock_region *plr = rdtgrp->plr;
+
+	if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
+		/*
+		 * Default group cannot be a pseudo-locked region so we can
+		 * free closid here.
+		 */
+		closid_free(rdtgrp->closid);
+		goto free;
+	}
+
+	pseudo_lock_cstates_relax(plr);
+	debugfs_remove_recursive(rdtgrp->plr->debugfs_dir);
+	device_destroy(pseudo_lock_class, MKDEV(pseudo_lock_major, plr->minor));
+	pseudo_lock_minor_release(plr->minor);
+
+free:
+	pseudo_lock_free(rdtgrp);
+}
+
+static int pseudo_lock_dev_open(struct inode *inode, struct file *filp)
+{
+	struct rdtgroup *rdtgrp;
+
+	mutex_lock(&rdtgroup_mutex);
+
+	rdtgrp = region_find_by_minor(iminor(inode));
+	if (!rdtgrp) {
+		mutex_unlock(&rdtgroup_mutex);
+		return -ENODEV;
+	}
+
+	filp->private_data = rdtgrp;
+	atomic_inc(&rdtgrp->waitcount);
+	/* Perform a non-seekable open - llseek is not supported */
+	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
+
+	mutex_unlock(&rdtgroup_mutex);
+
+	return 0;
+}
+
+static int pseudo_lock_dev_release(struct inode *inode, struct file *filp)
+{
+	struct rdtgroup *rdtgrp;
+
+	mutex_lock(&rdtgroup_mutex);
+	rdtgrp = filp->private_data;
+	WARN_ON(!rdtgrp);
+	if (!rdtgrp) {
+		mutex_unlock(&rdtgroup_mutex);
+		return -ENODEV;
+	}
+	filp->private_data = NULL;
+	atomic_dec(&rdtgrp->waitcount);
+	mutex_unlock(&rdtgroup_mutex);
+	return 0;
+}
+
+static int pseudo_lock_dev_mremap(struct vm_area_struct *area)
+{
+	/* Not supported */
+	return -EINVAL;
+}
+
+static const struct vm_operations_struct pseudo_mmap_ops = {
+	.mremap = pseudo_lock_dev_mremap,
+};
+
+static int pseudo_lock_dev_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	unsigned long vsize = vma->vm_end - vma->vm_start;
+	unsigned long off = vma->vm_pgoff << PAGE_SHIFT;
+	struct pseudo_lock_region *plr;
+	struct rdtgroup *rdtgrp;
+	unsigned long physical;
+	unsigned long psize;
+
+	mutex_lock(&rdtgroup_mutex);
+
+	rdtgrp = filp->private_data;
+	WARN_ON(!rdtgrp);
+	if (!rdtgrp) {
+		mutex_unlock(&rdtgroup_mutex);
+		return -ENODEV;
+	}
+
+	plr = rdtgrp->plr;
+
+	if (!plr->d) {
+		mutex_unlock(&rdtgroup_mutex);
+		return -ENODEV;
+	}
+
+	/*
+	 * Task is required to run with affinity to the cpus associated
+	 * with the pseudo-locked region. If this is not the case the task
+	 * may be scheduled elsewhere and invalidate entries in the
+	 * pseudo-locked region.
+	 */
+	if (!cpumask_subset(&current->cpus_allowed, &plr->d->cpu_mask)) {
+		mutex_unlock(&rdtgroup_mutex);
+		return -EINVAL;
+	}
+
+	physical = __pa(plr->kmem) >> PAGE_SHIFT;
+	psize = plr->size - off;
+
+	if (off > plr->size) {
+		mutex_unlock(&rdtgroup_mutex);
+		return -ENOSPC;
+	}
+
+	/*
+	 * Ensure changes are carried directly to the memory being mapped,
+	 * do not allow copy-on-write mapping.
+	 */
+	if (!(vma->vm_flags & VM_SHARED)) {
+		mutex_unlock(&rdtgroup_mutex);
+		return -EINVAL;
+	}
+
+	if (vsize > psize) {
+		mutex_unlock(&rdtgroup_mutex);
+		return -ENOSPC;
+	}
+
+	memset(plr->kmem + off, 0, vsize);
+
+	if (remap_pfn_range(vma, vma->vm_start, physical + vma->vm_pgoff,
+			    vsize, vma->vm_page_prot)) {
+		mutex_unlock(&rdtgroup_mutex);
+		return -EAGAIN;
+	}
+	vma->vm_ops = &pseudo_mmap_ops;
+	mutex_unlock(&rdtgroup_mutex);
+	return 0;
+}
+
+static const struct file_operations pseudo_lock_dev_fops = {
+	.owner =	THIS_MODULE,
+	.llseek =	no_llseek,
+	.read =		NULL,
+	.write =	NULL,
+	.open =		pseudo_lock_dev_open,
+	.release =	pseudo_lock_dev_release,
+	.mmap =		pseudo_lock_dev_mmap,
+};
+
+static char *pseudo_lock_devnode(struct device *dev, umode_t *mode)
+{
+	struct rdtgroup *rdtgrp;
+
+	rdtgrp = dev_get_drvdata(dev);
+	if (mode)
+		*mode = 0600;
+	return kasprintf(GFP_KERNEL, "pseudo_lock/%s", rdtgrp->kn->name);
+}
+
+int rdt_pseudo_lock_init(void)
+{
+	int ret;
+
+	ret = register_chrdev(0, "pseudo_lock", &pseudo_lock_dev_fops);
+	if (ret < 0)
+		return ret;
+
+	pseudo_lock_major = ret;
+
+	pseudo_lock_class = class_create(THIS_MODULE, "pseudo_lock");
+	if (IS_ERR(pseudo_lock_class)) {
+		ret = PTR_ERR(pseudo_lock_class);
+		unregister_chrdev(pseudo_lock_major, "pseudo_lock");
+		return ret;
+	}
+
+	pseudo_lock_class->devnode = pseudo_lock_devnode;
+	return 0;
+}
+
+void rdt_pseudo_lock_release(void)
+{
+	class_destroy(pseudo_lock_class);
+	pseudo_lock_class = NULL;
+	unregister_chrdev(pseudo_lock_major, "pseudo_lock");
+	pseudo_lock_major = 0;
+}