kernel/irq/matrix.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (C) 2017 Thomas Gleixner <tglx@linutronix.de>
   3
   4 #include <linux/spinlock.h>
   5 #include <linux/seq_file.h>
   6 #include <linux/bitmap.h>
   7 #include <linux/percpu.h>
   8 #include <linux/cpu.h>
   9 #include <linux/irq.h>
  10
  11 #define IRQ_MATRIX_SIZE (BITS_TO_LONGS(IRQ_MATRIX_BITS) * sizeof(unsigned long))
  12
  13 struct cpumap {
  14         unsigned int            available;
  15         unsigned int            allocated;
  16         unsigned int            managed;
  17         bool                    initialized;
  18         bool                    online;
  19         unsigned long           alloc_map[IRQ_MATRIX_SIZE];
  20         unsigned long           managed_map[IRQ_MATRIX_SIZE];
  21 };
  22
  23 struct irq_matrix {
  24         unsigned int            matrix_bits;
  25         unsigned int            alloc_start;
  26         unsigned int            alloc_end;
  27         unsigned int            alloc_size;
  28         unsigned int            global_available;
  29         unsigned int            global_reserved;
  30         unsigned int            systembits_inalloc;
  31         unsigned int            total_allocated;
  32         unsigned int            online_maps;
  33         struct cpumap __percpu  *maps;
  34         unsigned long           scratch_map[IRQ_MATRIX_SIZE];
  35         unsigned long           system_map[IRQ_MATRIX_SIZE];
  36 };
  37
  38 #define CREATE_TRACE_POINTS
  39 #include <trace/events/irq_matrix.h>
  40
  41 /**
  42  * irq_alloc_matrix - Allocate a irq_matrix structure and initialize it
  43  * @matrix_bits:        Number of matrix bits must be <= IRQ_MATRIX_BITS
  44  * @alloc_start:        From which bit the allocation search starts
  45  * @alloc_end:          At which bit the allocation search ends, i.e first
  46  *                      invalid bit
  47  */
  48 __init struct irq_matrix *irq_alloc_matrix(unsigned int matrix_bits,
  49                                            unsigned int alloc_start,
  50                                            unsigned int alloc_end)
  51 {
  52         struct irq_matrix *m;
  53
  54         if (matrix_bits > IRQ_MATRIX_BITS)
  55                 return NULL;
  56
  57         m = kzalloc(sizeof(*m), GFP_KERNEL);
  58         if (!m)
  59                 return NULL;
  60
  61         m->matrix_bits = matrix_bits;
  62         m->alloc_start = alloc_start;
  63         m->alloc_end = alloc_end;
  64         m->alloc_size = alloc_end - alloc_start;
  65         m->maps = alloc_percpu(*m->maps);
  66         if (!m->maps) {
  67                 kfree(m);
  68                 return NULL;
  69         }
  70         return m;
  71 }
  72
  73 /**
  74  * irq_matrix_online - Bring the local CPU matrix online
  75  * @m:          Matrix pointer
  76  */
  77 void irq_matrix_online(struct irq_matrix *m)
  78 {
  79         struct cpumap *cm = this_cpu_ptr(m->maps);
  80
  81         BUG_ON(cm->online);
  82
  83         if (!cm->initialized) {
  84                 cm->available = m->alloc_size;
  85                 cm->available -= cm->managed + m->systembits_inalloc;
  86                 cm->initialized = true;
  87         }
  88         m->global_available += cm->available;
  89         cm->online = true;
  90         m->online_maps++;
  91         trace_irq_matrix_online(m);
  92 }
  93
  94 /**
  95  * irq_matrix_offline - Bring the local CPU matrix offline
  96  * @m:          Matrix pointer
  97  */
  98 void irq_matrix_offline(struct irq_matrix *m)
  99 {
 100         struct cpumap *cm = this_cpu_ptr(m->maps);
 101
 102         /* Update the global available size */
 103         m->global_available -= cm->available;
 104         cm->online = false;
 105         m->online_maps--;
 106         trace_irq_matrix_offline(m);
 107 }
 108
 109 static unsigned int matrix_alloc_area(struct irq_matrix *m, struct cpumap *cm,
 110                                       unsigned int num, bool managed)
 111 {
 112         unsigned int area, start = m->alloc_start;
 113         unsigned int end = m->alloc_end;
 114
 115         bitmap_or(m->scratch_map, cm->managed_map, m->system_map, end);
 116         bitmap_or(m->scratch_map, m->scratch_map, cm->alloc_map, end);
 117         area = bitmap_find_next_zero_area(m->scratch_map, end, start, num, 0);
 118         if (area >= end)
 119                 return area;
 120         if (managed)
 121                 bitmap_set(cm->managed_map, area, num);
 122         else
 123                 bitmap_set(cm->alloc_map, area, num);
 124         return area;
 125 }
 126
 127 /* Find the best CPU which has the lowest vector allocation count */
 128 static unsigned int matrix_find_best_cpu(struct irq_matrix *m,
 129                                         const struct cpumask *msk)
 130 {
 131         unsigned int cpu, best_cpu, maxavl = 0;
 132         struct cpumap *cm;
 133
 134         best_cpu = UINT_MAX;
 135
 136         for_each_cpu(cpu, msk) {
 137                 cm = per_cpu_ptr(m->maps, cpu);
 138
 139                 if (!cm->online || cm->available <= maxavl)
 140                         continue;
 141
 142                 best_cpu = cpu;
 143                 maxavl = cm->available;
 144         }
 145         return best_cpu;
 146 }
 147
 148 /**
 149  * irq_matrix_assign_system - Assign system wide entry in the matrix
 150  * @m:          Matrix pointer
 151  * @bit:        Which bit to reserve
 152  * @replace:    Replace an already allocated vector with a system
 153  *              vector at the same bit position.
 154  *
 155  * The BUG_ON()s below are on purpose. If this goes wrong in the
 156  * early boot process, then the chance to survive is about zero.
 157  * If this happens when the system is life, it's not much better.
 158  */
 159 void irq_matrix_assign_system(struct irq_matrix *m, unsigned int bit,
 160                               bool replace)
 161 {
 162         struct cpumap *cm = this_cpu_ptr(m->maps);
 163
 164         BUG_ON(bit > m->matrix_bits);
 165         BUG_ON(m->online_maps > 1 || (m->online_maps && !replace));
 166
 167         set_bit(bit, m->system_map);
 168         if (replace) {
 169                 BUG_ON(!test_and_clear_bit(bit, cm->alloc_map));
 170                 cm->allocated--;
 171                 m->total_allocated--;
 172         }
 173         if (bit >= m->alloc_start && bit < m->alloc_end)
 174                 m->systembits_inalloc++;
 175
 176         trace_irq_matrix_assign_system(bit, m);
 177 }
 178
 179 /**
 180  * irq_matrix_reserve_managed - Reserve a managed interrupt in a CPU map
 181  * @m:          Matrix pointer
 182  * @msk:        On which CPUs the bits should be reserved.
 183  *
 184  * Can be called for offline CPUs. Note, this will only reserve one bit
 185  * on all CPUs in @msk, but it's not guaranteed that the bits are at the
 186  * same offset on all CPUs
 187  */
 188 int irq_matrix_reserve_managed(struct irq_matrix *m, const struct cpumask *msk)
 189 {
 190         unsigned int cpu, failed_cpu;
 191
 192         for_each_cpu(cpu, msk) {
 193                 struct cpumap *cm = per_cpu_ptr(m->maps, cpu);
 194                 unsigned int bit;
 195
 196                 bit = matrix_alloc_area(m, cm, 1, true);
 197                 if (bit >= m->alloc_end)
 198                         goto cleanup;
 199                 cm->managed++;
 200                 if (cm->online) {
 201                         cm->available--;
 202                         m->global_available--;
 203                 }
 204                 trace_irq_matrix_reserve_managed(bit, cpu, m, cm);
 205         }
 206         return 0;
 207 cleanup:
 208         failed_cpu = cpu;
 209         for_each_cpu(cpu, msk) {
 210                 if (cpu == failed_cpu)
 211                         break;
 212                 irq_matrix_remove_managed(m, cpumask_of(cpu));
 213         }
 214         return -ENOSPC;
 215 }
 216
 217 /**
 218  * irq_matrix_remove_managed - Remove managed interrupts in a CPU map
 219  * @m:          Matrix pointer
 220  * @msk:        On which CPUs the bits should be removed
 221  *
 222  * Can be called for offline CPUs
 223  *
 224  * This removes not allocated managed interrupts from the map. It does
 225  * not matter which one because the managed interrupts free their
 226  * allocation when they shut down. If not, the accounting is screwed,
 227  * but all what can be done at this point is warn about it.
 228  */
 229 void irq_matrix_remove_managed(struct irq_matrix *m, const struct cpumask *msk)
 230 {
 231         unsigned int cpu;
 232
 233         for_each_cpu(cpu, msk) {
 234                 struct cpumap *cm = per_cpu_ptr(m->maps, cpu);
 235                 unsigned int bit, end = m->alloc_end;
 236
 237                 if (WARN_ON_ONCE(!cm->managed))
 238                         continue;
 239
 240                 /* Get managed bit which are not allocated */
 241                 bitmap_andnot(m->scratch_map, cm->managed_map, cm->alloc_map, end);
 242
 243                 bit = find_first_bit(m->scratch_map, end);
 244                 if (WARN_ON_ONCE(bit >= end))
 245                         continue;
 246
 247                 clear_bit(bit, cm->managed_map);
 248
 249                 cm->managed--;
 250                 if (cm->online) {
 251                         cm->available++;
 252                         m->global_available++;
 253                 }
 254                 trace_irq_matrix_remove_managed(bit, cpu, m, cm);
 255         }
 256 }
 257
 258 /**
 259  * irq_matrix_alloc_managed - Allocate a managed interrupt in a CPU map
 260  * @m:          Matrix pointer
 261  * @cpu:        On which CPU the interrupt should be allocated
 262  */
 263 int irq_matrix_alloc_managed(struct irq_matrix *m, const struct cpumask *msk,
 264                              unsigned int *mapped_cpu)
 265 {
 266         unsigned int bit, cpu, end = m->alloc_end;
 267         struct cpumap *cm;
 268
 269         if (cpumask_empty(msk))
 270                 return -EINVAL;
 271
 272         cpu = matrix_find_best_cpu(m, msk);
 273         if (cpu == UINT_MAX)
 274                 return -ENOSPC;
 275
 276         cm = per_cpu_ptr(m->maps, cpu);
 277         end = m->alloc_end;
 278         /* Get managed bit which are not allocated */
 279         bitmap_andnot(m->scratch_map, cm->managed_map, cm->alloc_map, end);
 280         bit = find_first_bit(m->scratch_map, end);
 281         if (bit >= end)
 282                 return -ENOSPC;
 283         set_bit(bit, cm->alloc_map);
 284         cm->allocated++;
 285         m->total_allocated++;
 286         *mapped_cpu = cpu;
 287         trace_irq_matrix_alloc_managed(bit, cpu, m, cm);
 288         return bit;
 289 }
 290
 291 /**
 292  * irq_matrix_assign - Assign a preallocated interrupt in the local CPU map
 293  * @m:          Matrix pointer
 294  * @bit:        Which bit to mark
 295  *
 296  * This should only be used to mark preallocated vectors
 297  */
 298 void irq_matrix_assign(struct irq_matrix *m, unsigned int bit)
 299 {
 300         struct cpumap *cm = this_cpu_ptr(m->maps);
 301
 302         if (WARN_ON_ONCE(bit < m->alloc_start || bit >= m->alloc_end))
 303                 return;
 304         if (WARN_ON_ONCE(test_and_set_bit(bit, cm->alloc_map)))
 305                 return;
 306         cm->allocated++;
 307         m->total_allocated++;
 308         cm->available--;
 309         m->global_available--;
 310         trace_irq_matrix_assign(bit, smp_processor_id(), m, cm);
 311 }
 312
 313 /**
 314  * irq_matrix_reserve - Reserve interrupts
 315  * @m:          Matrix pointer
 316  *
 317  * This is merily a book keeping call. It increments the number of globally
 318  * reserved interrupt bits w/o actually allocating them. This allows to
 319  * setup interrupt descriptors w/o assigning low level resources to it.
 320  * The actual allocation happens when the interrupt gets activated.
 321  */
 322 void irq_matrix_reserve(struct irq_matrix *m)
 323 {
 324         if (m->global_reserved <= m->global_available &&
 325             m->global_reserved + 1 > m->global_available)
 326                 pr_warn("Interrupt reservation exceeds available resources\n");
 327
 328         m->global_reserved++;
 329         trace_irq_matrix_reserve(m);
 330 }
 331
 332 /**
 333  * irq_matrix_remove_reserved - Remove interrupt reservation
 334  * @m:          Matrix pointer
 335  *
 336  * This is merily a book keeping call. It decrements the number of globally
 337  * reserved interrupt bits. This is used to undo irq_matrix_reserve() when the
 338  * interrupt was never in use and a real vector allocated, which undid the
 339  * reservation.
 340  */
 341 void irq_matrix_remove_reserved(struct irq_matrix *m)
 342 {
 343         m->global_reserved--;
 344         trace_irq_matrix_remove_reserved(m);
 345 }
 346
 347 /**
 348  * irq_matrix_alloc - Allocate a regular interrupt in a CPU map
 349  * @m:          Matrix pointer
 350  * @msk:        Which CPUs to search in
 351  * @reserved:   Allocate previously reserved interrupts
 352  * @mapped_cpu: Pointer to store the CPU for which the irq was allocated
 353  */
 354 int irq_matrix_alloc(struct irq_matrix *m, const struct cpumask *msk,
 355                      bool reserved, unsigned int *mapped_cpu)
 356 {
 357         unsigned int cpu, bit;
 358         struct cpumap *cm;
 359
 360         cpu = matrix_find_best_cpu(m, msk);
 361         if (cpu == UINT_MAX)
 362                 return -ENOSPC;
 363
 364         cm = per_cpu_ptr(m->maps, cpu);
 365         bit = matrix_alloc_area(m, cm, 1, false);
 366         if (bit >= m->alloc_end)
 367                 return -ENOSPC;
 368         cm->allocated++;
 369         cm->available--;
 370         m->total_allocated++;
 371         m->global_available--;
 372         if (reserved)
 373                 m->global_reserved--;
 374         *mapped_cpu = cpu;
 375         trace_irq_matrix_alloc(bit, cpu, m, cm);
 376         return bit;
 377
 378 }
 379
 380 /**
 381  * irq_matrix_free - Free allocated interrupt in the matrix
 382  * @m:          Matrix pointer
 383  * @cpu:        Which CPU map needs be updated
 384  * @bit:        The bit to remove
 385  * @managed:    If true, the interrupt is managed and not accounted
 386  *              as available.
 387  */
 388 void irq_matrix_free(struct irq_matrix *m, unsigned int cpu,
 389                      unsigned int bit, bool managed)
 390 {
 391         struct cpumap *cm = per_cpu_ptr(m->maps, cpu);
 392
 393         if (WARN_ON_ONCE(bit < m->alloc_start || bit >= m->alloc_end))
 394                 return;
 395
 396         clear_bit(bit, cm->alloc_map);
 397         cm->allocated--;
 398
 399         if (cm->online)
 400                 m->total_allocated--;
 401
 402         if (!managed) {
 403                 cm->available++;
 404                 if (cm->online)
 405                         m->global_available++;
 406         }
 407         trace_irq_matrix_free(bit, cpu, m, cm);
 408 }
 409
 410 /**
 411  * irq_matrix_available - Get the number of globally available irqs
 412  * @m:          Pointer to the matrix to query
 413  * @cpudown:    If true, the local CPU is about to go down, adjust
 414  *              the number of available irqs accordingly
 415  */
 416 unsigned int irq_matrix_available(struct irq_matrix *m, bool cpudown)
 417 {
 418         struct cpumap *cm = this_cpu_ptr(m->maps);
 419
 420         if (!cpudown)
 421                 return m->global_available;
 422         return m->global_available - cm->available;
 423 }
 424
 425 /**
 426  * irq_matrix_reserved - Get the number of globally reserved irqs
 427  * @m:          Pointer to the matrix to query
 428  */
 429 unsigned int irq_matrix_reserved(struct irq_matrix *m)
 430 {
 431         return m->global_reserved;
 432 }
 433
 434 /**
 435  * irq_matrix_allocated - Get the number of allocated irqs on the local cpu
 436  * @m:          Pointer to the matrix to search
 437  *
 438  * This returns number of allocated irqs
 439  */
 440 unsigned int irq_matrix_allocated(struct irq_matrix *m)
 441 {
 442         struct cpumap *cm = this_cpu_ptr(m->maps);
 443
 444         return cm->allocated;
 445 }
 446
 447 #ifdef CONFIG_GENERIC_IRQ_DEBUGFS
 448 /**
 449  * irq_matrix_debug_show - Show detailed allocation information
 450  * @sf:         Pointer to the seq_file to print to
 451  * @m:          Pointer to the matrix allocator
 452  * @ind:        Indentation for the print format
 453  *
 454  * Note, this is a lockless snapshot.
 455  */
 456 void irq_matrix_debug_show(struct seq_file *sf, struct irq_matrix *m, int ind)
 457 {
 458         unsigned int nsys = bitmap_weight(m->system_map, m->matrix_bits);
 459         int cpu;
 460
 461         seq_printf(sf, "Online bitmaps:   %6u\n", m->online_maps);
 462         seq_printf(sf, "Global available: %6u\n", m->global_available);
 463         seq_printf(sf, "Global reserved:  %6u\n", m->global_reserved);
 464         seq_printf(sf, "Total allocated:  %6u\n", m->total_allocated);
 465         seq_printf(sf, "System: %u: %*pbl\n", nsys, m->matrix_bits,
 466                    m->system_map);
 467         seq_printf(sf, "%*s| CPU | avl | man | act | vectors\n", ind, " ");
 468         cpus_read_lock();
 469         for_each_online_cpu(cpu) {
 470                 struct cpumap *cm = per_cpu_ptr(m->maps, cpu);
 471
 472                 seq_printf(sf, "%*s %4d  %4u  %4u  %4u  %*pbl\n", ind, " ",
 473                            cpu, cm->available, cm->managed, cm->allocated,
 474                            m->matrix_bits, cm->alloc_map);
 475         }
 476         cpus_read_unlock();
 477 }
 478 #endif