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Linux/arch/x86/kernel/cpu/resctrl/pseudo_lock.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * Resource Director Technology (RDT)
  4  *
  5  * Pseudo-locking support built on top of Cache Allocation Technology (CAT)
  6  *
  7  * Copyright (C) 2018 Intel Corporation
  8  *
  9  * Author: Reinette Chatre <reinette.chatre@intel.com>
 10  */
 11 
 12 #define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
 13 
 14 #include <linux/cacheinfo.h>
 15 #include <linux/cpu.h>
 16 #include <linux/cpumask.h>
 17 #include <linux/debugfs.h>
 18 #include <linux/kthread.h>
 19 #include <linux/mman.h>
 20 #include <linux/perf_event.h>
 21 #include <linux/pm_qos.h>
 22 #include <linux/slab.h>
 23 #include <linux/uaccess.h>
 24 
 25 #include <asm/cacheflush.h>
 26 #include <asm/intel-family.h>
 27 #include <asm/resctrl_sched.h>
 28 #include <asm/perf_event.h>
 29 
 30 #include "../../events/perf_event.h" /* For X86_CONFIG() */
 31 #include "internal.h"
 32 
 33 #define CREATE_TRACE_POINTS
 34 #include "pseudo_lock_event.h"
 35 
 36 /*
 37  * The bits needed to disable hardware prefetching varies based on the
 38  * platform. During initialization we will discover which bits to use.
 39  */
 40 static u64 prefetch_disable_bits;
 41 
 42 /*
 43  * Major number assigned to and shared by all devices exposing
 44  * pseudo-locked regions.
 45  */
 46 static unsigned int pseudo_lock_major;
 47 static unsigned long pseudo_lock_minor_avail = GENMASK(MINORBITS, 0);
 48 static struct class *pseudo_lock_class;
 49 
 50 /**
 51  * get_prefetch_disable_bits - prefetch disable bits of supported platforms
 52  *
 53  * Capture the list of platforms that have been validated to support
 54  * pseudo-locking. This includes testing to ensure pseudo-locked regions
 55  * with low cache miss rates can be created under variety of load conditions
 56  * as well as that these pseudo-locked regions can maintain their low cache
 57  * miss rates under variety of load conditions for significant lengths of time.
 58  *
 59  * After a platform has been validated to support pseudo-locking its
 60  * hardware prefetch disable bits are included here as they are documented
 61  * in the SDM.
 62  *
 63  * When adding a platform here also add support for its cache events to
 64  * measure_cycles_perf_fn()
 65  *
 66  * Return:
 67  * If platform is supported, the bits to disable hardware prefetchers, 0
 68  * if platform is not supported.
 69  */
 70 static u64 get_prefetch_disable_bits(void)
 71 {
 72         if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL ||
 73             boot_cpu_data.x86 != 6)
 74                 return 0;
 75 
 76         switch (boot_cpu_data.x86_model) {
 77         case INTEL_FAM6_BROADWELL_X:
 78                 /*
 79                  * SDM defines bits of MSR_MISC_FEATURE_CONTROL register
 80                  * as:
 81                  * 0    L2 Hardware Prefetcher Disable (R/W)
 82                  * 1    L2 Adjacent Cache Line Prefetcher Disable (R/W)
 83                  * 2    DCU Hardware Prefetcher Disable (R/W)
 84                  * 3    DCU IP Prefetcher Disable (R/W)
 85                  * 63:4 Reserved
 86                  */
 87                 return 0xF;
 88         case INTEL_FAM6_ATOM_GOLDMONT:
 89         case INTEL_FAM6_ATOM_GOLDMONT_PLUS:
 90                 /*
 91                  * SDM defines bits of MSR_MISC_FEATURE_CONTROL register
 92                  * as:
 93                  * 0     L2 Hardware Prefetcher Disable (R/W)
 94                  * 1     Reserved
 95                  * 2     DCU Hardware Prefetcher Disable (R/W)
 96                  * 63:3  Reserved
 97                  */
 98                 return 0x5;
 99         }
100 
101         return 0;
102 }
103 
104 /**
105  * pseudo_lock_minor_get - Obtain available minor number
106  * @minor: Pointer to where new minor number will be stored
107  *
108  * A bitmask is used to track available minor numbers. Here the next free
109  * minor number is marked as unavailable and returned.
110  *
111  * Return: 0 on success, <0 on failure.
112  */
113 static int pseudo_lock_minor_get(unsigned int *minor)
114 {
115         unsigned long first_bit;
116 
117         first_bit = find_first_bit(&pseudo_lock_minor_avail, MINORBITS);
118 
119         if (first_bit == MINORBITS)
120                 return -ENOSPC;
121 
122         __clear_bit(first_bit, &pseudo_lock_minor_avail);
123         *minor = first_bit;
124 
125         return 0;
126 }
127 
128 /**
129  * pseudo_lock_minor_release - Return minor number to available
130  * @minor: The minor number made available
131  */
132 static void pseudo_lock_minor_release(unsigned int minor)
133 {
134         __set_bit(minor, &pseudo_lock_minor_avail);
135 }
136 
137 /**
138  * region_find_by_minor - Locate a pseudo-lock region by inode minor number
139  * @minor: The minor number of the device representing pseudo-locked region
140  *
141  * When the character device is accessed we need to determine which
142  * pseudo-locked region it belongs to. This is done by matching the minor
143  * number of the device to the pseudo-locked region it belongs.
144  *
145  * Minor numbers are assigned at the time a pseudo-locked region is associated
146  * with a cache instance.
147  *
148  * Return: On success return pointer to resource group owning the pseudo-locked
149  *         region, NULL on failure.
150  */
151 static struct rdtgroup *region_find_by_minor(unsigned int minor)
152 {
153         struct rdtgroup *rdtgrp, *rdtgrp_match = NULL;
154 
155         list_for_each_entry(rdtgrp, &rdt_all_groups, rdtgroup_list) {
156                 if (rdtgrp->plr && rdtgrp->plr->minor == minor) {
157                         rdtgrp_match = rdtgrp;
158                         break;
159                 }
160         }
161         return rdtgrp_match;
162 }
163 
164 /**
165  * pseudo_lock_pm_req - A power management QoS request list entry
166  * @list:       Entry within the @pm_reqs list for a pseudo-locked region
167  * @req:        PM QoS request
168  */
169 struct pseudo_lock_pm_req {
170         struct list_head list;
171         struct dev_pm_qos_request req;
172 };
173 
174 static void pseudo_lock_cstates_relax(struct pseudo_lock_region *plr)
175 {
176         struct pseudo_lock_pm_req *pm_req, *next;
177 
178         list_for_each_entry_safe(pm_req, next, &plr->pm_reqs, list) {
179                 dev_pm_qos_remove_request(&pm_req->req);
180                 list_del(&pm_req->list);
181                 kfree(pm_req);
182         }
183 }
184 
185 /**
186  * pseudo_lock_cstates_constrain - Restrict cores from entering C6
187  *
188  * To prevent the cache from being affected by power management entering
189  * C6 has to be avoided. This is accomplished by requesting a latency
190  * requirement lower than lowest C6 exit latency of all supported
191  * platforms as found in the cpuidle state tables in the intel_idle driver.
192  * At this time it is possible to do so with a single latency requirement
193  * for all supported platforms.
194  *
195  * Since Goldmont is supported, which is affected by X86_BUG_MONITOR,
196  * the ACPI latencies need to be considered while keeping in mind that C2
197  * may be set to map to deeper sleep states. In this case the latency
198  * requirement needs to prevent entering C2 also.
199  */
200 static int pseudo_lock_cstates_constrain(struct pseudo_lock_region *plr)
201 {
202         struct pseudo_lock_pm_req *pm_req;
203         int cpu;
204         int ret;
205 
206         for_each_cpu(cpu, &plr->d->cpu_mask) {
207                 pm_req = kzalloc(sizeof(*pm_req), GFP_KERNEL);
208                 if (!pm_req) {
209                         rdt_last_cmd_puts("Failure to allocate memory for PM QoS\n");
210                         ret = -ENOMEM;
211                         goto out_err;
212                 }
213                 ret = dev_pm_qos_add_request(get_cpu_device(cpu),
214                                              &pm_req->req,
215                                              DEV_PM_QOS_RESUME_LATENCY,
216                                              30);
217                 if (ret < 0) {
218                         rdt_last_cmd_printf("Failed to add latency req CPU%d\n",
219                                             cpu);
220                         kfree(pm_req);
221                         ret = -1;
222                         goto out_err;
223                 }
224                 list_add(&pm_req->list, &plr->pm_reqs);
225         }
226 
227         return 0;
228 
229 out_err:
230         pseudo_lock_cstates_relax(plr);
231         return ret;
232 }
233 
234 /**
235  * pseudo_lock_region_clear - Reset pseudo-lock region data
236  * @plr: pseudo-lock region
237  *
238  * All content of the pseudo-locked region is reset - any memory allocated
239  * freed.
240  *
241  * Return: void
242  */
243 static void pseudo_lock_region_clear(struct pseudo_lock_region *plr)
244 {
245         plr->size = 0;
246         plr->line_size = 0;
247         kfree(plr->kmem);
248         plr->kmem = NULL;
249         plr->r = NULL;
250         if (plr->d)
251                 plr->d->plr = NULL;
252         plr->d = NULL;
253         plr->cbm = 0;
254         plr->debugfs_dir = NULL;
255 }
256 
257 /**
258  * pseudo_lock_region_init - Initialize pseudo-lock region information
259  * @plr: pseudo-lock region
260  *
261  * Called after user provided a schemata to be pseudo-locked. From the
262  * schemata the &struct pseudo_lock_region is on entry already initialized
263  * with the resource, domain, and capacity bitmask. Here the information
264  * required for pseudo-locking is deduced from this data and &struct
265  * pseudo_lock_region initialized further. This information includes:
266  * - size in bytes of the region to be pseudo-locked
267  * - cache line size to know the stride with which data needs to be accessed
268  *   to be pseudo-locked
269  * - a cpu associated with the cache instance on which the pseudo-locking
270  *   flow can be executed
271  *
272  * Return: 0 on success, <0 on failure. Descriptive error will be written
273  * to last_cmd_status buffer.
274  */
275 static int pseudo_lock_region_init(struct pseudo_lock_region *plr)
276 {
277         struct cpu_cacheinfo *ci;
278         int ret;
279         int i;
280 
281         /* Pick the first cpu we find that is associated with the cache. */
282         plr->cpu = cpumask_first(&plr->d->cpu_mask);
283 
284         if (!cpu_online(plr->cpu)) {
285                 rdt_last_cmd_printf("CPU %u associated with cache not online\n",
286                                     plr->cpu);
287                 ret = -ENODEV;
288                 goto out_region;
289         }
290 
291         ci = get_cpu_cacheinfo(plr->cpu);
292 
293         plr->size = rdtgroup_cbm_to_size(plr->r, plr->d, plr->cbm);
294 
295         for (i = 0; i < ci->num_leaves; i++) {
296                 if (ci->info_list[i].level == plr->r->cache_level) {
297                         plr->line_size = ci->info_list[i].coherency_line_size;
298                         return 0;
299                 }
300         }
301 
302         ret = -1;
303         rdt_last_cmd_puts("Unable to determine cache line size\n");
304 out_region:
305         pseudo_lock_region_clear(plr);
306         return ret;
307 }
308 
309 /**
310  * pseudo_lock_init - Initialize a pseudo-lock region
311  * @rdtgrp: resource group to which new pseudo-locked region will belong
312  *
313  * A pseudo-locked region is associated with a resource group. When this
314  * association is created the pseudo-locked region is initialized. The
315  * details of the pseudo-locked region are not known at this time so only
316  * allocation is done and association established.
317  *
318  * Return: 0 on success, <0 on failure
319  */
320 static int pseudo_lock_init(struct rdtgroup *rdtgrp)
321 {
322         struct pseudo_lock_region *plr;
323 
324         plr = kzalloc(sizeof(*plr), GFP_KERNEL);
325         if (!plr)
326                 return -ENOMEM;
327 
328         init_waitqueue_head(&plr->lock_thread_wq);
329         INIT_LIST_HEAD(&plr->pm_reqs);
330         rdtgrp->plr = plr;
331         return 0;
332 }
333 
334 /**
335  * pseudo_lock_region_alloc - Allocate kernel memory that will be pseudo-locked
336  * @plr: pseudo-lock region
337  *
338  * Initialize the details required to set up the pseudo-locked region and
339  * allocate the contiguous memory that will be pseudo-locked to the cache.
340  *
341  * Return: 0 on success, <0 on failure.  Descriptive error will be written
342  * to last_cmd_status buffer.
343  */
344 static int pseudo_lock_region_alloc(struct pseudo_lock_region *plr)
345 {
346         int ret;
347 
348         ret = pseudo_lock_region_init(plr);
349         if (ret < 0)
350                 return ret;
351 
352         /*
353          * We do not yet support contiguous regions larger than
354          * KMALLOC_MAX_SIZE.
355          */
356         if (plr->size > KMALLOC_MAX_SIZE) {
357                 rdt_last_cmd_puts("Requested region exceeds maximum size\n");
358                 ret = -E2BIG;
359                 goto out_region;
360         }
361 
362         plr->kmem = kzalloc(plr->size, GFP_KERNEL);
363         if (!plr->kmem) {
364                 rdt_last_cmd_puts("Unable to allocate memory\n");
365                 ret = -ENOMEM;
366                 goto out_region;
367         }
368 
369         ret = 0;
370         goto out;
371 out_region:
372         pseudo_lock_region_clear(plr);
373 out:
374         return ret;
375 }
376 
377 /**
378  * pseudo_lock_free - Free a pseudo-locked region
379  * @rdtgrp: resource group to which pseudo-locked region belonged
380  *
381  * The pseudo-locked region's resources have already been released, or not
382  * yet created at this point. Now it can be freed and disassociated from the
383  * resource group.
384  *
385  * Return: void
386  */
387 static void pseudo_lock_free(struct rdtgroup *rdtgrp)
388 {
389         pseudo_lock_region_clear(rdtgrp->plr);
390         kfree(rdtgrp->plr);
391         rdtgrp->plr = NULL;
392 }
393 
394 /**
395  * pseudo_lock_fn - Load kernel memory into cache
396  * @_rdtgrp: resource group to which pseudo-lock region belongs
397  *
398  * This is the core pseudo-locking flow.
399  *
400  * First we ensure that the kernel memory cannot be found in the cache.
401  * Then, while taking care that there will be as little interference as
402  * possible, the memory to be loaded is accessed while core is running
403  * with class of service set to the bitmask of the pseudo-locked region.
404  * After this is complete no future CAT allocations will be allowed to
405  * overlap with this bitmask.
406  *
407  * Local register variables are utilized to ensure that the memory region
408  * to be locked is the only memory access made during the critical locking
409  * loop.
410  *
411  * Return: 0. Waiter on waitqueue will be woken on completion.
412  */
413 static int pseudo_lock_fn(void *_rdtgrp)
414 {
415         struct rdtgroup *rdtgrp = _rdtgrp;
416         struct pseudo_lock_region *plr = rdtgrp->plr;
417         u32 rmid_p, closid_p;
418         unsigned long i;
419 #ifdef CONFIG_KASAN
420         /*
421          * The registers used for local register variables are also used
422          * when KASAN is active. When KASAN is active we use a regular
423          * variable to ensure we always use a valid pointer, but the cost
424          * is that this variable will enter the cache through evicting the
425          * memory we are trying to lock into the cache. Thus expect lower
426          * pseudo-locking success rate when KASAN is active.
427          */
428         unsigned int line_size;
429         unsigned int size;
430         void *mem_r;
431 #else
432         register unsigned int line_size asm("esi");
433         register unsigned int size asm("edi");
434         register void *mem_r asm(_ASM_BX);
435 #endif /* CONFIG_KASAN */
436 
437         /*
438          * Make sure none of the allocated memory is cached. If it is we
439          * will get a cache hit in below loop from outside of pseudo-locked
440          * region.
441          * wbinvd (as opposed to clflush/clflushopt) is required to
442          * increase likelihood that allocated cache portion will be filled
443          * with associated memory.
444          */
445         native_wbinvd();
446 
447         /*
448          * Always called with interrupts enabled. By disabling interrupts
449          * ensure that we will not be preempted during this critical section.
450          */
451         local_irq_disable();
452 
453         /*
454          * Call wrmsr and rdmsr as directly as possible to avoid tracing
455          * clobbering local register variables or affecting cache accesses.
456          *
457          * Disable the hardware prefetcher so that when the end of the memory
458          * being pseudo-locked is reached the hardware will not read beyond
459          * the buffer and evict pseudo-locked memory read earlier from the
460          * cache.
461          */
462         __wrmsr(MSR_MISC_FEATURE_CONTROL, prefetch_disable_bits, 0x0);
463         closid_p = this_cpu_read(pqr_state.cur_closid);
464         rmid_p = this_cpu_read(pqr_state.cur_rmid);
465         mem_r = plr->kmem;
466         size = plr->size;
467         line_size = plr->line_size;
468         /*
469          * Critical section begin: start by writing the closid associated
470          * with the capacity bitmask of the cache region being
471          * pseudo-locked followed by reading of kernel memory to load it
472          * into the cache.
473          */
474         __wrmsr(IA32_PQR_ASSOC, rmid_p, rdtgrp->closid);
475         /*
476          * Cache was flushed earlier. Now access kernel memory to read it
477          * into cache region associated with just activated plr->closid.
478          * Loop over data twice:
479          * - In first loop the cache region is shared with the page walker
480          *   as it populates the paging structure caches (including TLB).
481          * - In the second loop the paging structure caches are used and
482          *   cache region is populated with the memory being referenced.
483          */
484         for (i = 0; i < size; i += PAGE_SIZE) {
485                 /*
486                  * Add a barrier to prevent speculative execution of this
487                  * loop reading beyond the end of the buffer.
488                  */
489                 rmb();
490                 asm volatile("mov (%0,%1,1), %%eax\n\t"
491                         :
492                         : "r" (mem_r), "r" (i)
493                         : "%eax", "memory");
494         }
495         for (i = 0; i < size; i += line_size) {
496                 /*
497                  * Add a barrier to prevent speculative execution of this
498                  * loop reading beyond the end of the buffer.
499                  */
500                 rmb();
501                 asm volatile("mov (%0,%1,1), %%eax\n\t"
502                         :
503                         : "r" (mem_r), "r" (i)
504                         : "%eax", "memory");
505         }
506         /*
507          * Critical section end: restore closid with capacity bitmask that
508          * does not overlap with pseudo-locked region.
509          */
510         __wrmsr(IA32_PQR_ASSOC, rmid_p, closid_p);
511 
512         /* Re-enable the hardware prefetcher(s) */
513         wrmsr(MSR_MISC_FEATURE_CONTROL, 0x0, 0x0);
514         local_irq_enable();
515 
516         plr->thread_done = 1;
517         wake_up_interruptible(&plr->lock_thread_wq);
518         return 0;
519 }
520 
521 /**
522  * rdtgroup_monitor_in_progress - Test if monitoring in progress
523  * @r: resource group being queried
524  *
525  * Return: 1 if monitor groups have been created for this resource
526  * group, 0 otherwise.
527  */
528 static int rdtgroup_monitor_in_progress(struct rdtgroup *rdtgrp)
529 {
530         return !list_empty(&rdtgrp->mon.crdtgrp_list);
531 }
532 
533 /**
534  * rdtgroup_locksetup_user_restrict - Restrict user access to group
535  * @rdtgrp: resource group needing access restricted
536  *
537  * A resource group used for cache pseudo-locking cannot have cpus or tasks
538  * assigned to it. This is communicated to the user by restricting access
539  * to all the files that can be used to make such changes.
540  *
541  * Permissions restored with rdtgroup_locksetup_user_restore()
542  *
543  * Return: 0 on success, <0 on failure. If a failure occurs during the
544  * restriction of access an attempt will be made to restore permissions but
545  * the state of the mode of these files will be uncertain when a failure
546  * occurs.
547  */
548 static int rdtgroup_locksetup_user_restrict(struct rdtgroup *rdtgrp)
549 {
550         int ret;
551 
552         ret = rdtgroup_kn_mode_restrict(rdtgrp, "tasks");
553         if (ret)
554                 return ret;
555 
556         ret = rdtgroup_kn_mode_restrict(rdtgrp, "cpus");
557         if (ret)
558                 goto err_tasks;
559 
560         ret = rdtgroup_kn_mode_restrict(rdtgrp, "cpus_list");
561         if (ret)
562                 goto err_cpus;
563 
564         if (rdt_mon_capable) {
565                 ret = rdtgroup_kn_mode_restrict(rdtgrp, "mon_groups");
566                 if (ret)
567                         goto err_cpus_list;
568         }
569 
570         ret = 0;
571         goto out;
572 
573 err_cpus_list:
574         rdtgroup_kn_mode_restore(rdtgrp, "cpus_list", 0777);
575 err_cpus:
576         rdtgroup_kn_mode_restore(rdtgrp, "cpus", 0777);
577 err_tasks:
578         rdtgroup_kn_mode_restore(rdtgrp, "tasks", 0777);
579 out:
580         return ret;
581 }
582 
583 /**
584  * rdtgroup_locksetup_user_restore - Restore user access to group
585  * @rdtgrp: resource group needing access restored
586  *
587  * Restore all file access previously removed using
588  * rdtgroup_locksetup_user_restrict()
589  *
590  * Return: 0 on success, <0 on failure.  If a failure occurs during the
591  * restoration of access an attempt will be made to restrict permissions
592  * again but the state of the mode of these files will be uncertain when
593  * a failure occurs.
594  */
595 static int rdtgroup_locksetup_user_restore(struct rdtgroup *rdtgrp)
596 {
597         int ret;
598 
599         ret = rdtgroup_kn_mode_restore(rdtgrp, "tasks", 0777);
600         if (ret)
601                 return ret;
602 
603         ret = rdtgroup_kn_mode_restore(rdtgrp, "cpus", 0777);
604         if (ret)
605                 goto err_tasks;
606 
607         ret = rdtgroup_kn_mode_restore(rdtgrp, "cpus_list", 0777);
608         if (ret)
609                 goto err_cpus;
610 
611         if (rdt_mon_capable) {
612                 ret = rdtgroup_kn_mode_restore(rdtgrp, "mon_groups", 0777);
613                 if (ret)
614                         goto err_cpus_list;
615         }
616 
617         ret = 0;
618         goto out;
619 
620 err_cpus_list:
621         rdtgroup_kn_mode_restrict(rdtgrp, "cpus_list");
622 err_cpus:
623         rdtgroup_kn_mode_restrict(rdtgrp, "cpus");
624 err_tasks:
625         rdtgroup_kn_mode_restrict(rdtgrp, "tasks");
626 out:
627         return ret;
628 }
629 
630 /**
631  * rdtgroup_locksetup_enter - Resource group enters locksetup mode
632  * @rdtgrp: resource group requested to enter locksetup mode
633  *
634  * A resource group enters locksetup mode to reflect that it would be used
635  * to represent a pseudo-locked region and is in the process of being set
636  * up to do so. A resource group used for a pseudo-locked region would
637  * lose the closid associated with it so we cannot allow it to have any
638  * tasks or cpus assigned nor permit tasks or cpus to be assigned in the
639  * future. Monitoring of a pseudo-locked region is not allowed either.
640  *
641  * The above and more restrictions on a pseudo-locked region are checked
642  * for and enforced before the resource group enters the locksetup mode.
643  *
644  * Returns: 0 if the resource group successfully entered locksetup mode, <0
645  * on failure. On failure the last_cmd_status buffer is updated with text to
646  * communicate details of failure to the user.
647  */
648 int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp)
649 {
650         int ret;
651 
652         /*
653          * The default resource group can neither be removed nor lose the
654          * default closid associated with it.
655          */
656         if (rdtgrp == &rdtgroup_default) {
657                 rdt_last_cmd_puts("Cannot pseudo-lock default group\n");
658                 return -EINVAL;
659         }
660 
661         /*
662          * Cache Pseudo-locking not supported when CDP is enabled.
663          *
664          * Some things to consider if you would like to enable this
665          * support (using L3 CDP as example):
666          * - When CDP is enabled two separate resources are exposed,
667          *   L3DATA and L3CODE, but they are actually on the same cache.
668          *   The implication for pseudo-locking is that if a
669          *   pseudo-locked region is created on a domain of one
670          *   resource (eg. L3CODE), then a pseudo-locked region cannot
671          *   be created on that same domain of the other resource
672          *   (eg. L3DATA). This is because the creation of a
673          *   pseudo-locked region involves a call to wbinvd that will
674          *   affect all cache allocations on particular domain.
675          * - Considering the previous, it may be possible to only
676          *   expose one of the CDP resources to pseudo-locking and
677          *   hide the other. For example, we could consider to only
678          *   expose L3DATA and since the L3 cache is unified it is
679          *   still possible to place instructions there are execute it.
680          * - If only one region is exposed to pseudo-locking we should
681          *   still keep in mind that availability of a portion of cache
682          *   for pseudo-locking should take into account both resources.
683          *   Similarly, if a pseudo-locked region is created in one
684          *   resource, the portion of cache used by it should be made
685          *   unavailable to all future allocations from both resources.
686          */
687         if (rdt_resources_all[RDT_RESOURCE_L3DATA].alloc_enabled ||
688             rdt_resources_all[RDT_RESOURCE_L2DATA].alloc_enabled) {
689                 rdt_last_cmd_puts("CDP enabled\n");
690                 return -EINVAL;
691         }
692 
693         /*
694          * Not knowing the bits to disable prefetching implies that this
695          * platform does not support Cache Pseudo-Locking.
696          */
697         prefetch_disable_bits = get_prefetch_disable_bits();
698         if (prefetch_disable_bits == 0) {
699                 rdt_last_cmd_puts("Pseudo-locking not supported\n");
700                 return -EINVAL;
701         }
702 
703         if (rdtgroup_monitor_in_progress(rdtgrp)) {
704                 rdt_last_cmd_puts("Monitoring in progress\n");
705                 return -EINVAL;
706         }
707 
708         if (rdtgroup_tasks_assigned(rdtgrp)) {
709                 rdt_last_cmd_puts("Tasks assigned to resource group\n");
710                 return -EINVAL;
711         }
712 
713         if (!cpumask_empty(&rdtgrp->cpu_mask)) {
714                 rdt_last_cmd_puts("CPUs assigned to resource group\n");
715                 return -EINVAL;
716         }
717 
718         if (rdtgroup_locksetup_user_restrict(rdtgrp)) {
719                 rdt_last_cmd_puts("Unable to modify resctrl permissions\n");
720                 return -EIO;
721         }
722 
723         ret = pseudo_lock_init(rdtgrp);
724         if (ret) {
725                 rdt_last_cmd_puts("Unable to init pseudo-lock region\n");
726                 goto out_release;
727         }
728 
729         /*
730          * If this system is capable of monitoring a rmid would have been
731          * allocated when the control group was created. This is not needed
732          * anymore when this group would be used for pseudo-locking. This
733          * is safe to call on platforms not capable of monitoring.
734          */
735         free_rmid(rdtgrp->mon.rmid);
736 
737         ret = 0;
738         goto out;
739 
740 out_release:
741         rdtgroup_locksetup_user_restore(rdtgrp);
742 out:
743         return ret;
744 }
745 
746 /**
747  * rdtgroup_locksetup_exit - resource group exist locksetup mode
748  * @rdtgrp: resource group
749  *
750  * When a resource group exits locksetup mode the earlier restrictions are
751  * lifted.
752  *
753  * Return: 0 on success, <0 on failure
754  */
755 int rdtgroup_locksetup_exit(struct rdtgroup *rdtgrp)
756 {
757         int ret;
758 
759         if (rdt_mon_capable) {
760                 ret = alloc_rmid();
761                 if (ret < 0) {
762                         rdt_last_cmd_puts("Out of RMIDs\n");
763                         return ret;
764                 }
765                 rdtgrp->mon.rmid = ret;
766         }
767 
768         ret = rdtgroup_locksetup_user_restore(rdtgrp);
769         if (ret) {
770                 free_rmid(rdtgrp->mon.rmid);
771                 return ret;
772         }
773 
774         pseudo_lock_free(rdtgrp);
775         return 0;
776 }
777 
778 /**
779  * rdtgroup_cbm_overlaps_pseudo_locked - Test if CBM or portion is pseudo-locked
780  * @d: RDT domain
781  * @cbm: CBM to test
782  *
783  * @d represents a cache instance and @cbm a capacity bitmask that is
784  * considered for it. Determine if @cbm overlaps with any existing
785  * pseudo-locked region on @d.
786  *
787  * @cbm is unsigned long, even if only 32 bits are used, to make the
788  * bitmap functions work correctly.
789  *
790  * Return: true if @cbm overlaps with pseudo-locked region on @d, false
791  * otherwise.
792  */
793 bool rdtgroup_cbm_overlaps_pseudo_locked(struct rdt_domain *d, unsigned long cbm)
794 {
795         unsigned int cbm_len;
796         unsigned long cbm_b;
797 
798         if (d->plr) {
799                 cbm_len = d->plr->r->cache.cbm_len;
800                 cbm_b = d->plr->cbm;
801                 if (bitmap_intersects(&cbm, &cbm_b, cbm_len))
802                         return true;
803         }
804         return false;
805 }
806 
807 /**
808  * rdtgroup_pseudo_locked_in_hierarchy - Pseudo-locked region in cache hierarchy
809  * @d: RDT domain under test
810  *
811  * The setup of a pseudo-locked region affects all cache instances within
812  * the hierarchy of the region. It is thus essential to know if any
813  * pseudo-locked regions exist within a cache hierarchy to prevent any
814  * attempts to create new pseudo-locked regions in the same hierarchy.
815  *
816  * Return: true if a pseudo-locked region exists in the hierarchy of @d or
817  *         if it is not possible to test due to memory allocation issue,
818  *         false otherwise.
819  */
820 bool rdtgroup_pseudo_locked_in_hierarchy(struct rdt_domain *d)
821 {
822         cpumask_var_t cpu_with_psl;
823         struct rdt_resource *r;
824         struct rdt_domain *d_i;
825         bool ret = false;
826 
827         if (!zalloc_cpumask_var(&cpu_with_psl, GFP_KERNEL))
828                 return true;
829 
830         /*
831          * First determine which cpus have pseudo-locked regions
832          * associated with them.
833          */
834         for_each_alloc_enabled_rdt_resource(r) {
835                 list_for_each_entry(d_i, &r->domains, list) {
836                         if (d_i->plr)
837                                 cpumask_or(cpu_with_psl, cpu_with_psl,
838                                            &d_i->cpu_mask);
839                 }
840         }
841 
842         /*
843          * Next test if new pseudo-locked region would intersect with
844          * existing region.
845          */
846         if (cpumask_intersects(&d->cpu_mask, cpu_with_psl))
847                 ret = true;
848 
849         free_cpumask_var(cpu_with_psl);
850         return ret;
851 }
852 
853 /**
854  * measure_cycles_lat_fn - Measure cycle latency to read pseudo-locked memory
855  * @_plr: pseudo-lock region to measure
856  *
857  * There is no deterministic way to test if a memory region is cached. One
858  * way is to measure how long it takes to read the memory, the speed of
859  * access is a good way to learn how close to the cpu the data was. Even
860  * more, if the prefetcher is disabled and the memory is read at a stride
861  * of half the cache line, then a cache miss will be easy to spot since the
862  * read of the first half would be significantly slower than the read of
863  * the second half.
864  *
865  * Return: 0. Waiter on waitqueue will be woken on completion.
866  */
867 static int measure_cycles_lat_fn(void *_plr)
868 {
869         struct pseudo_lock_region *plr = _plr;
870         unsigned long i;
871         u64 start, end;
872         void *mem_r;
873 
874         local_irq_disable();
875         /*
876          * Disable hardware prefetchers.
877          */
878         wrmsr(MSR_MISC_FEATURE_CONTROL, prefetch_disable_bits, 0x0);
879         mem_r = READ_ONCE(plr->kmem);
880         /*
881          * Dummy execute of the time measurement to load the needed
882          * instructions into the L1 instruction cache.
883          */
884         start = rdtsc_ordered();
885         for (i = 0; i < plr->size; i += 32) {
886                 start = rdtsc_ordered();
887                 asm volatile("mov (%0,%1,1), %%eax\n\t"
888                              :
889                              : "r" (mem_r), "r" (i)
890                              : "%eax", "memory");
891                 end = rdtsc_ordered();
892                 trace_pseudo_lock_mem_latency((u32)(end - start));
893         }
894         wrmsr(MSR_MISC_FEATURE_CONTROL, 0x0, 0x0);
895         local_irq_enable();
896         plr->thread_done = 1;
897         wake_up_interruptible(&plr->lock_thread_wq);
898         return 0;
899 }
900 
901 /*
902  * Create a perf_event_attr for the hit and miss perf events that will
903  * be used during the performance measurement. A perf_event maintains
904  * a pointer to its perf_event_attr so a unique attribute structure is
905  * created for each perf_event.
906  *
907  * The actual configuration of the event is set right before use in order
908  * to use the X86_CONFIG macro.
909  */
910 static struct perf_event_attr perf_miss_attr = {
911         .type           = PERF_TYPE_RAW,
912         .size           = sizeof(struct perf_event_attr),
913         .pinned         = 1,
914         .disabled       = 0,
915         .exclude_user   = 1,
916 };
917 
918 static struct perf_event_attr perf_hit_attr = {
919         .type           = PERF_TYPE_RAW,
920         .size           = sizeof(struct perf_event_attr),
921         .pinned         = 1,
922         .disabled       = 0,
923         .exclude_user   = 1,
924 };
925 
926 struct residency_counts {
927         u64 miss_before, hits_before;
928         u64 miss_after,  hits_after;
929 };
930 
931 static int measure_residency_fn(struct perf_event_attr *miss_attr,
932                                 struct perf_event_attr *hit_attr,
933                                 struct pseudo_lock_region *plr,
934                                 struct residency_counts *counts)
935 {
936         u64 hits_before = 0, hits_after = 0, miss_before = 0, miss_after = 0;
937         struct perf_event *miss_event, *hit_event;
938         int hit_pmcnum, miss_pmcnum;
939         unsigned int line_size;
940         unsigned int size;
941         unsigned long i;
942         void *mem_r;
943         u64 tmp;
944 
945         miss_event = perf_event_create_kernel_counter(miss_attr, plr->cpu,
946                                                       NULL, NULL, NULL);
947         if (IS_ERR(miss_event))
948                 goto out;
949 
950         hit_event = perf_event_create_kernel_counter(hit_attr, plr->cpu,
951                                                      NULL, NULL, NULL);
952         if (IS_ERR(hit_event))
953                 goto out_miss;
954 
955         local_irq_disable();
956         /*
957          * Check any possible error state of events used by performing
958          * one local read.
959          */
960         if (perf_event_read_local(miss_event, &tmp, NULL, NULL)) {
961                 local_irq_enable();
962                 goto out_hit;
963         }
964         if (perf_event_read_local(hit_event, &tmp, NULL, NULL)) {
965                 local_irq_enable();
966                 goto out_hit;
967         }
968 
969         /*
970          * Disable hardware prefetchers.
971          */
972         wrmsr(MSR_MISC_FEATURE_CONTROL, prefetch_disable_bits, 0x0);
973 
974         /* Initialize rest of local variables */
975         /*
976          * Performance event has been validated right before this with
977          * interrupts disabled - it is thus safe to read the counter index.
978          */
979         miss_pmcnum = x86_perf_rdpmc_index(miss_event);
980         hit_pmcnum = x86_perf_rdpmc_index(hit_event);
981         line_size = READ_ONCE(plr->line_size);
982         mem_r = READ_ONCE(plr->kmem);
983         size = READ_ONCE(plr->size);
984 
985         /*
986          * Read counter variables twice - first to load the instructions
987          * used in L1 cache, second to capture accurate value that does not
988          * include cache misses incurred because of instruction loads.
989          */
990         rdpmcl(hit_pmcnum, hits_before);
991         rdpmcl(miss_pmcnum, miss_before);
992         /*
993          * From SDM: Performing back-to-back fast reads are not guaranteed
994          * to be monotonic.
995          * Use LFENCE to ensure all previous instructions are retired
996          * before proceeding.
997          */
998         rmb();
999         rdpmcl(hit_pmcnum, hits_before);
1000         rdpmcl(miss_pmcnum, miss_before);
1001         /*
1002          * Use LFENCE to ensure all previous instructions are retired
1003          * before proceeding.
1004          */
1005         rmb();
1006         for (i = 0; i < size; i += line_size) {
1007                 /*
1008                  * Add a barrier to prevent speculative execution of this
1009                  * loop reading beyond the end of the buffer.
1010                  */
1011                 rmb();
1012                 asm volatile("mov (%0,%1,1), %%eax\n\t"
1013                              :
1014                              : "r" (mem_r), "r" (i)
1015                              : "%eax", "memory");
1016         }
1017         /*
1018          * Use LFENCE to ensure all previous instructions are retired
1019          * before proceeding.
1020          */
1021         rmb();
1022         rdpmcl(hit_pmcnum, hits_after);
1023         rdpmcl(miss_pmcnum, miss_after);
1024         /*
1025          * Use LFENCE to ensure all previous instructions are retired
1026          * before proceeding.
1027          */
1028         rmb();
1029         /* Re-enable hardware prefetchers */
1030         wrmsr(MSR_MISC_FEATURE_CONTROL, 0x0, 0x0);
1031         local_irq_enable();
1032 out_hit:
1033         perf_event_release_kernel(hit_event);
1034 out_miss:
1035         perf_event_release_kernel(miss_event);
1036 out:
1037         /*
1038          * All counts will be zero on failure.
1039          */
1040         counts->miss_before = miss_before;
1041         counts->hits_before = hits_before;
1042         counts->miss_after  = miss_after;
1043         counts->hits_after  = hits_after;
1044         return 0;
1045 }
1046 
1047 static int measure_l2_residency(void *_plr)
1048 {
1049         struct pseudo_lock_region *plr = _plr;
1050         struct residency_counts counts = {0};
1051 
1052         /*
1053          * Non-architectural event for the Goldmont Microarchitecture
1054          * from Intel x86 Architecture Software Developer Manual (SDM):
1055          * MEM_LOAD_UOPS_RETIRED D1H (event number)
1056          * Umask values:
1057          *     L2_HIT   02H
1058          *     L2_MISS  10H
1059          */
1060         switch (boot_cpu_data.x86_model) {
1061         case INTEL_FAM6_ATOM_GOLDMONT:
1062         case INTEL_FAM6_ATOM_GOLDMONT_PLUS:
1063                 perf_miss_attr.config = X86_CONFIG(.event = 0xd1,
1064                                                    .umask = 0x10);
1065                 perf_hit_attr.config = X86_CONFIG(.event = 0xd1,
1066                                                   .umask = 0x2);
1067                 break;
1068         default:
1069                 goto out;
1070         }
1071 
1072         measure_residency_fn(&perf_miss_attr, &perf_hit_attr, plr, &counts);
1073         /*
1074          * If a failure prevented the measurements from succeeding
1075          * tracepoints will still be written and all counts will be zero.
1076          */
1077         trace_pseudo_lock_l2(counts.hits_after - counts.hits_before,
1078                              counts.miss_after - counts.miss_before);
1079 out:
1080         plr->thread_done = 1;
1081         wake_up_interruptible(&plr->lock_thread_wq);
1082         return 0;
1083 }
1084 
1085 static int measure_l3_residency(void *_plr)
1086 {
1087         struct pseudo_lock_region *plr = _plr;
1088         struct residency_counts counts = {0};
1089 
1090         /*
1091          * On Broadwell Microarchitecture the MEM_LOAD_UOPS_RETIRED event
1092          * has two "no fix" errata associated with it: BDM35 and BDM100. On
1093          * this platform the following events are used instead:
1094          * LONGEST_LAT_CACHE 2EH (Documented in SDM)
1095          *       REFERENCE 4FH
1096          *       MISS      41H
1097          */
1098 
1099         switch (boot_cpu_data.x86_model) {
1100         case INTEL_FAM6_BROADWELL_X:
1101                 /* On BDW the hit event counts references, not hits */
1102                 perf_hit_attr.config = X86_CONFIG(.event = 0x2e,
1103                                                   .umask = 0x4f);
1104                 perf_miss_attr.config = X86_CONFIG(.event = 0x2e,
1105                                                    .umask = 0x41);
1106                 break;
1107         default:
1108                 goto out;
1109         }
1110 
1111         measure_residency_fn(&perf_miss_attr, &perf_hit_attr, plr, &counts);
1112         /*
1113          * If a failure prevented the measurements from succeeding
1114          * tracepoints will still be written and all counts will be zero.
1115          */
1116 
1117         counts.miss_after -= counts.miss_before;
1118         if (boot_cpu_data.x86_model == INTEL_FAM6_BROADWELL_X) {
1119                 /*
1120                  * On BDW references and misses are counted, need to adjust.
1121                  * Sometimes the "hits" counter is a bit more than the
1122                  * references, for example, x references but x + 1 hits.
1123                  * To not report invalid hit values in this case we treat
1124                  * that as misses equal to references.
1125                  */
1126                 /* First compute the number of cache references measured */
1127                 counts.hits_after -= counts.hits_before;
1128                 /* Next convert references to cache hits */
1129                 counts.hits_after -= min(counts.miss_after, counts.hits_after);
1130         } else {
1131                 counts.hits_after -= counts.hits_before;
1132         }
1133 
1134         trace_pseudo_lock_l3(counts.hits_after, counts.miss_after);
1135 out:
1136         plr->thread_done = 1;
1137         wake_up_interruptible(&plr->lock_thread_wq);
1138         return 0;
1139 }
1140 
1141 /**
1142  * pseudo_lock_measure_cycles - Trigger latency measure to pseudo-locked region
1143  *
1144  * The measurement of latency to access a pseudo-locked region should be
1145  * done from a cpu that is associated with that pseudo-locked region.
1146  * Determine which cpu is associated with this region and start a thread on
1147  * that cpu to perform the measurement, wait for that thread to complete.
1148  *
1149  * Return: 0 on success, <0 on failure
1150  */
1151 static int pseudo_lock_measure_cycles(struct rdtgroup *rdtgrp, int sel)
1152 {
1153         struct pseudo_lock_region *plr = rdtgrp->plr;
1154         struct task_struct *thread;
1155         unsigned int cpu;
1156         int ret = -1;
1157 
1158         cpus_read_lock();
1159         mutex_lock(&rdtgroup_mutex);
1160 
1161         if (rdtgrp->flags & RDT_DELETED) {
1162                 ret = -ENODEV;
1163                 goto out;
1164         }
1165 
1166         if (!plr->d) {
1167                 ret = -ENODEV;
1168                 goto out;
1169         }
1170 
1171         plr->thread_done = 0;
1172         cpu = cpumask_first(&plr->d->cpu_mask);
1173         if (!cpu_online(cpu)) {
1174                 ret = -ENODEV;
1175                 goto out;
1176         }
1177 
1178         plr->cpu = cpu;
1179 
1180         if (sel == 1)
1181                 thread = kthread_create_on_node(measure_cycles_lat_fn, plr,
1182                                                 cpu_to_node(cpu),
1183                                                 "pseudo_lock_measure/%u",
1184                                                 cpu);
1185         else if (sel == 2)
1186                 thread = kthread_create_on_node(measure_l2_residency, plr,
1187                                                 cpu_to_node(cpu),
1188                                                 "pseudo_lock_measure/%u",
1189                                                 cpu);
1190         else if (sel == 3)
1191                 thread = kthread_create_on_node(measure_l3_residency, plr,
1192                                                 cpu_to_node(cpu),
1193                                                 "pseudo_lock_measure/%u",
1194                                                 cpu);
1195         else
1196                 goto out;
1197 
1198         if (IS_ERR(thread)) {
1199                 ret = PTR_ERR(thread);
1200                 goto out;
1201         }
1202         kthread_bind(thread, cpu);
1203         wake_up_process(thread);
1204 
1205         ret = wait_event_interruptible(plr->lock_thread_wq,
1206                                        plr->thread_done == 1);
1207         if (ret < 0)
1208                 goto out;
1209 
1210         ret = 0;
1211 
1212 out:
1213         mutex_unlock(&rdtgroup_mutex);
1214         cpus_read_unlock();
1215         return ret;
1216 }
1217 
1218 static ssize_t pseudo_lock_measure_trigger(struct file *file,
1219                                            const char __user *user_buf,
1220                                            size_t count, loff_t *ppos)
1221 {
1222         struct rdtgroup *rdtgrp = file->private_data;
1223         size_t buf_size;
1224         char buf[32];
1225         int ret;
1226         int sel;
1227 
1228         buf_size = min(count, (sizeof(buf) - 1));
1229         if (copy_from_user(buf, user_buf, buf_size))
1230                 return -EFAULT;
1231 
1232         buf[buf_size] = '\0';
1233         ret = kstrtoint(buf, 10, &sel);
1234         if (ret == 0) {
1235                 if (sel != 1 && sel != 2 && sel != 3)
1236                         return -EINVAL;
1237                 ret = debugfs_file_get(file->f_path.dentry);
1238                 if (ret)
1239                         return ret;
1240                 ret = pseudo_lock_measure_cycles(rdtgrp, sel);
1241                 if (ret == 0)
1242                         ret = count;
1243                 debugfs_file_put(file->f_path.dentry);
1244         }
1245 
1246         return ret;
1247 }
1248 
1249 static const struct file_operations pseudo_measure_fops = {
1250         .write = pseudo_lock_measure_trigger,
1251         .open = simple_open,
1252         .llseek = default_llseek,
1253 };
1254 
1255 /**
1256  * rdtgroup_pseudo_lock_create - Create a pseudo-locked region
1257  * @rdtgrp: resource group to which pseudo-lock region belongs
1258  *
1259  * Called when a resource group in the pseudo-locksetup mode receives a
1260  * valid schemata that should be pseudo-locked. Since the resource group is
1261  * in pseudo-locksetup mode the &struct pseudo_lock_region has already been
1262  * allocated and initialized with the essential information. If a failure
1263  * occurs the resource group remains in the pseudo-locksetup mode with the
1264  * &struct pseudo_lock_region associated with it, but cleared from all
1265  * information and ready for the user to re-attempt pseudo-locking by
1266  * writing the schemata again.
1267  *
1268  * Return: 0 if the pseudo-locked region was successfully pseudo-locked, <0
1269  * on failure. Descriptive error will be written to last_cmd_status buffer.
1270  */
1271 int rdtgroup_pseudo_lock_create(struct rdtgroup *rdtgrp)
1272 {
1273         struct pseudo_lock_region *plr = rdtgrp->plr;
1274         struct task_struct *thread;
1275         unsigned int new_minor;
1276         struct device *dev;
1277         int ret;
1278 
1279         ret = pseudo_lock_region_alloc(plr);
1280         if (ret < 0)
1281                 return ret;
1282 
1283         ret = pseudo_lock_cstates_constrain(plr);
1284         if (ret < 0) {
1285                 ret = -EINVAL;
1286                 goto out_region;
1287         }
1288 
1289         plr->thread_done = 0;
1290 
1291         thread = kthread_create_on_node(pseudo_lock_fn, rdtgrp,
1292                                         cpu_to_node(plr->cpu),
1293                                         "pseudo_lock/%u", plr->cpu);
1294         if (IS_ERR(thread)) {
1295                 ret = PTR_ERR(thread);
1296                 rdt_last_cmd_printf("Locking thread returned error %d\n", ret);
1297                 goto out_cstates;
1298         }
1299 
1300         kthread_bind(thread, plr->cpu);
1301         wake_up_process(thread);
1302 
1303         ret = wait_event_interruptible(plr->lock_thread_wq,
1304                                        plr->thread_done == 1);
1305         if (ret < 0) {
1306                 /*
1307                  * If the thread does not get on the CPU for whatever
1308                  * reason and the process which sets up the region is
1309                  * interrupted then this will leave the thread in runnable
1310                  * state and once it gets on the CPU it will derefence
1311                  * the cleared, but not freed, plr struct resulting in an
1312                  * empty pseudo-locking loop.
1313                  */
1314                 rdt_last_cmd_puts("Locking thread interrupted\n");
1315                 goto out_cstates;
1316         }
1317 
1318         ret = pseudo_lock_minor_get(&new_minor);
1319         if (ret < 0) {
1320                 rdt_last_cmd_puts("Unable to obtain a new minor number\n");
1321                 goto out_cstates;
1322         }
1323 
1324         /*
1325          * Unlock access but do not release the reference. The
1326          * pseudo-locked region will still be here on return.
1327          *
1328          * The mutex has to be released temporarily to avoid a potential
1329          * deadlock with the mm->mmap_sem semaphore which is obtained in
1330          * the device_create() and debugfs_create_dir() callpath below
1331          * as well as before the mmap() callback is called.
1332          */
1333         mutex_unlock(&rdtgroup_mutex);
1334 
1335         if (!IS_ERR_OR_NULL(debugfs_resctrl)) {
1336                 plr->debugfs_dir = debugfs_create_dir(rdtgrp->kn->name,
1337                                                       debugfs_resctrl);
1338                 if (!IS_ERR_OR_NULL(plr->debugfs_dir))
1339                         debugfs_create_file("pseudo_lock_measure", 0200,
1340                                             plr->debugfs_dir, rdtgrp,
1341                                             &pseudo_measure_fops);
1342         }
1343 
1344         dev = device_create(pseudo_lock_class, NULL,
1345                             MKDEV(pseudo_lock_major, new_minor),
1346                             rdtgrp, "%s", rdtgrp->kn->name);
1347 
1348         mutex_lock(&rdtgroup_mutex);
1349 
1350         if (IS_ERR(dev)) {
1351                 ret = PTR_ERR(dev);
1352                 rdt_last_cmd_printf("Failed to create character device: %d\n",
1353                                     ret);
1354                 goto out_debugfs;
1355         }
1356 
1357         /* We released the mutex - check if group was removed while we did so */
1358         if (rdtgrp->flags & RDT_DELETED) {
1359                 ret = -ENODEV;
1360                 goto out_device;
1361         }
1362 
1363         plr->minor = new_minor;
1364 
1365         rdtgrp->mode = RDT_MODE_PSEUDO_LOCKED;
1366         closid_free(rdtgrp->closid);
1367         rdtgroup_kn_mode_restore(rdtgrp, "cpus", 0444);
1368         rdtgroup_kn_mode_restore(rdtgrp, "cpus_list", 0444);
1369 
1370         ret = 0;
1371         goto out;
1372 
1373 out_device:
1374         device_destroy(pseudo_lock_class, MKDEV(pseudo_lock_major, new_minor));
1375 out_debugfs:
1376         debugfs_remove_recursive(plr->debugfs_dir);
1377         pseudo_lock_minor_release(new_minor);
1378 out_cstates:
1379         pseudo_lock_cstates_relax(plr);
1380 out_region:
1381         pseudo_lock_region_clear(plr);
1382 out:
1383         return ret;
1384 }
1385 
1386 /**
1387  * rdtgroup_pseudo_lock_remove - Remove a pseudo-locked region
1388  * @rdtgrp: resource group to which the pseudo-locked region belongs
1389  *
1390  * The removal of a pseudo-locked region can be initiated when the resource
1391  * group is removed from user space via a "rmdir" from userspace or the
1392  * unmount of the resctrl filesystem. On removal the resource group does
1393  * not go back to pseudo-locksetup mode before it is removed, instead it is
1394  * removed directly. There is thus assymmetry with the creation where the
1395  * &struct pseudo_lock_region is removed here while it was not created in
1396  * rdtgroup_pseudo_lock_create().
1397  *
1398  * Return: void
1399  */
1400 void rdtgroup_pseudo_lock_remove(struct rdtgroup *rdtgrp)
1401 {
1402         struct pseudo_lock_region *plr = rdtgrp->plr;
1403 
1404         if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
1405                 /*
1406                  * Default group cannot be a pseudo-locked region so we can
1407                  * free closid here.
1408                  */
1409                 closid_free(rdtgrp->closid);
1410                 goto free;
1411         }
1412 
1413         pseudo_lock_cstates_relax(plr);
1414         debugfs_remove_recursive(rdtgrp->plr->debugfs_dir);
1415         device_destroy(pseudo_lock_class, MKDEV(pseudo_lock_major, plr->minor));
1416         pseudo_lock_minor_release(plr->minor);
1417 
1418 free:
1419         pseudo_lock_free(rdtgrp);
1420 }
1421 
1422 static int pseudo_lock_dev_open(struct inode *inode, struct file *filp)
1423 {
1424         struct rdtgroup *rdtgrp;
1425 
1426         mutex_lock(&rdtgroup_mutex);
1427 
1428         rdtgrp = region_find_by_minor(iminor(inode));
1429         if (!rdtgrp) {
1430                 mutex_unlock(&rdtgroup_mutex);
1431                 return -ENODEV;
1432         }
1433 
1434         filp->private_data = rdtgrp;
1435         atomic_inc(&rdtgrp->waitcount);
1436         /* Perform a non-seekable open - llseek is not supported */
1437         filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1438 
1439         mutex_unlock(&rdtgroup_mutex);
1440 
1441         return 0;
1442 }
1443 
1444 static int pseudo_lock_dev_release(struct inode *inode, struct file *filp)
1445 {
1446         struct rdtgroup *rdtgrp;
1447 
1448         mutex_lock(&rdtgroup_mutex);
1449         rdtgrp = filp->private_data;
1450         WARN_ON(!rdtgrp);
1451         if (!rdtgrp) {
1452                 mutex_unlock(&rdtgroup_mutex);
1453                 return -ENODEV;
1454         }
1455         filp->private_data = NULL;
1456         atomic_dec(&rdtgrp->waitcount);
1457         mutex_unlock(&rdtgroup_mutex);
1458         return 0;
1459 }
1460 
1461 static int pseudo_lock_dev_mremap(struct vm_area_struct *area)
1462 {
1463         /* Not supported */
1464         return -EINVAL;
1465 }
1466 
1467 static const struct vm_operations_struct pseudo_mmap_ops = {
1468         .mremap = pseudo_lock_dev_mremap,
1469 };
1470 
1471 static int pseudo_lock_dev_mmap(struct file *filp, struct vm_area_struct *vma)
1472 {
1473         unsigned long vsize = vma->vm_end - vma->vm_start;
1474         unsigned long off = vma->vm_pgoff << PAGE_SHIFT;
1475         struct pseudo_lock_region *plr;
1476         struct rdtgroup *rdtgrp;
1477         unsigned long physical;
1478         unsigned long psize;
1479 
1480         mutex_lock(&rdtgroup_mutex);
1481 
1482         rdtgrp = filp->private_data;
1483         WARN_ON(!rdtgrp);
1484         if (!rdtgrp) {
1485                 mutex_unlock(&rdtgroup_mutex);
1486                 return -ENODEV;
1487         }
1488 
1489         plr = rdtgrp->plr;
1490 
1491         if (!plr->d) {
1492                 mutex_unlock(&rdtgroup_mutex);
1493                 return -ENODEV;
1494         }
1495 
1496         /*
1497          * Task is required to run with affinity to the cpus associated
1498          * with the pseudo-locked region. If this is not the case the task
1499          * may be scheduled elsewhere and invalidate entries in the
1500          * pseudo-locked region.
1501          */
1502         if (!cpumask_subset(current->cpus_ptr, &plr->d->cpu_mask)) {
1503                 mutex_unlock(&rdtgroup_mutex);
1504                 return -EINVAL;
1505         }
1506 
1507         physical = __pa(plr->kmem) >> PAGE_SHIFT;
1508         psize = plr->size - off;
1509 
1510         if (off > plr->size) {
1511                 mutex_unlock(&rdtgroup_mutex);
1512                 return -ENOSPC;
1513         }
1514 
1515         /*
1516          * Ensure changes are carried directly to the memory being mapped,
1517          * do not allow copy-on-write mapping.
1518          */
1519         if (!(vma->vm_flags & VM_SHARED)) {
1520                 mutex_unlock(&rdtgroup_mutex);
1521                 return -EINVAL;
1522         }
1523 
1524         if (vsize > psize) {
1525                 mutex_unlock(&rdtgroup_mutex);
1526                 return -ENOSPC;
1527         }
1528 
1529         memset(plr->kmem + off, 0, vsize);
1530 
1531         if (remap_pfn_range(vma, vma->vm_start, physical + vma->vm_pgoff,
1532                             vsize, vma->vm_page_prot)) {
1533                 mutex_unlock(&rdtgroup_mutex);
1534                 return -EAGAIN;
1535         }
1536         vma->vm_ops = &pseudo_mmap_ops;
1537         mutex_unlock(&rdtgroup_mutex);
1538         return 0;
1539 }
1540 
1541 static const struct file_operations pseudo_lock_dev_fops = {
1542         .owner =        THIS_MODULE,
1543         .llseek =       no_llseek,
1544         .read =         NULL,
1545         .write =        NULL,
1546         .open =         pseudo_lock_dev_open,
1547         .release =      pseudo_lock_dev_release,
1548         .mmap =         pseudo_lock_dev_mmap,
1549 };
1550 
1551 static char *pseudo_lock_devnode(struct device *dev, umode_t *mode)
1552 {
1553         struct rdtgroup *rdtgrp;
1554 
1555         rdtgrp = dev_get_drvdata(dev);
1556         if (mode)
1557                 *mode = 0600;
1558         return kasprintf(GFP_KERNEL, "pseudo_lock/%s", rdtgrp->kn->name);
1559 }
1560 
1561 int rdt_pseudo_lock_init(void)
1562 {
1563         int ret;
1564 
1565         ret = register_chrdev(0, "pseudo_lock", &pseudo_lock_dev_fops);
1566         if (ret < 0)
1567                 return ret;
1568 
1569         pseudo_lock_major = ret;
1570 
1571         pseudo_lock_class = class_create(THIS_MODULE, "pseudo_lock");
1572         if (IS_ERR(pseudo_lock_class)) {
1573                 ret = PTR_ERR(pseudo_lock_class);
1574                 unregister_chrdev(pseudo_lock_major, "pseudo_lock");
1575                 return ret;
1576         }
1577 
1578         pseudo_lock_class->devnode = pseudo_lock_devnode;
1579         return 0;
1580 }
1581 
1582 void rdt_pseudo_lock_release(void)
1583 {
1584         class_destroy(pseudo_lock_class);
1585         pseudo_lock_class = NULL;
1586         unregister_chrdev(pseudo_lock_major, "pseudo_lock");
1587         pseudo_lock_major = 0;
1588 }
1589 

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