drivers/target/target_core_user.c

   1 /*
   2  * Copyright (C) 2013 Shaohua Li <shli@kernel.org>
   3  * Copyright (C) 2014 Red Hat, Inc.
   4  * Copyright (C) 2015 Arrikto, Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms and conditions of the GNU General Public License,
   8  * version 2, as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 #include <linux/spinlock.h>
  21 #include <linux/module.h>
  22 #include <linux/idr.h>
  23 #include <linux/kernel.h>
  24 #include <linux/timer.h>
  25 #include <linux/parser.h>
  26 #include <linux/vmalloc.h>
  27 #include <linux/uio_driver.h>
  28 #include <linux/stringify.h>
  29 #include <net/genetlink.h>
  30 #include <scsi/scsi_common.h>
  31 #include <scsi/scsi_proto.h>
  32 #include <target/target_core_base.h>
  33 #include <target/target_core_fabric.h>
  34 #include <target/target_core_backend.h>
  35
  36 #include <linux/target_core_user.h>
  37
  38 /*
  39  * Define a shared-memory interface for LIO to pass SCSI commands and
  40  * data to userspace for processing. This is to allow backends that
  41  * are too complex for in-kernel support to be possible.
  42  *
  43  * It uses the UIO framework to do a lot of the device-creation and
  44  * introspection work for us.
  45  *
  46  * See the .h file for how the ring is laid out. Note that while the
  47  * command ring is defined, the particulars of the data area are
  48  * not. Offset values in the command entry point to other locations
  49  * internal to the mmap()ed area. There is separate space outside the
  50  * command ring for data buffers. This leaves maximum flexibility for
  51  * moving buffer allocations, or even page flipping or other
  52  * allocation techniques, without altering the command ring layout.
  53  *
  54  * SECURITY:
  55  * The user process must be assumed to be malicious. There's no way to
  56  * prevent it breaking the command ring protocol if it wants, but in
  57  * order to prevent other issues we must only ever read *data* from
  58  * the shared memory area, not offsets or sizes. This applies to
  59  * command ring entries as well as the mailbox. Extra code needed for
  60  * this may have a 'UAM' comment.
  61  */
  62
  63
  64 #define TCMU_TIME_OUT (30 * MSEC_PER_SEC)
  65
  66 #define CMDR_SIZE (16 * 4096)
  67 #define DATA_SIZE (257 * 4096)
  68
  69 #define TCMU_RING_SIZE (CMDR_SIZE + DATA_SIZE)
  70
  71 static struct device *tcmu_root_device;
  72
  73 struct tcmu_hba {
  74         u32 host_id;
  75 };
  76
  77 #define TCMU_CONFIG_LEN 256
  78
  79 struct tcmu_dev {
  80         struct se_device se_dev;
  81
  82         char *name;
  83         struct se_hba *hba;
  84
  85 #define TCMU_DEV_BIT_OPEN 0
  86 #define TCMU_DEV_BIT_BROKEN 1
  87         unsigned long flags;
  88
  89         struct uio_info uio_info;
  90
  91         struct tcmu_mailbox *mb_addr;
  92         size_t dev_size;
  93         u32 cmdr_size;
  94         u32 cmdr_last_cleaned;
  95         /* Offset of data ring from start of mb */
  96         size_t data_off;
  97         size_t data_size;
  98         /* Ring head + tail values. */
  99         /* Must add data_off and mb_addr to get the address */
 100         size_t data_head;
 101         size_t data_tail;
 102
 103         wait_queue_head_t wait_cmdr;
 104         /* TODO should this be a mutex? */
 105         spinlock_t cmdr_lock;
 106
 107         struct idr commands;
 108         spinlock_t commands_lock;
 109
 110         struct timer_list timeout;
 111
 112         char dev_config[TCMU_CONFIG_LEN];
 113 };
 114
 115 #define TCMU_DEV(_se_dev) container_of(_se_dev, struct tcmu_dev, se_dev)
 116
 117 #define CMDR_OFF sizeof(struct tcmu_mailbox)
 118
 119 struct tcmu_cmd {
 120         struct se_cmd *se_cmd;
 121         struct tcmu_dev *tcmu_dev;
 122
 123         uint16_t cmd_id;
 124
 125         /* Can't use se_cmd->data_length when cleaning up expired cmds, because if
 126            cmd has been completed then accessing se_cmd is off limits */
 127         size_t data_length;
 128
 129         unsigned long deadline;
 130
 131 #define TCMU_CMD_BIT_EXPIRED 0
 132         unsigned long flags;
 133 };
 134
 135 static struct kmem_cache *tcmu_cmd_cache;
 136
 137 /* multicast group */
 138 enum tcmu_multicast_groups {
 139         TCMU_MCGRP_CONFIG,
 140 };
 141
 142 static const struct genl_multicast_group tcmu_mcgrps[] = {
 143         [TCMU_MCGRP_CONFIG] = { .name = "config", },
 144 };
 145
 146 /* Our generic netlink family */
 147 static struct genl_family tcmu_genl_family = {
 148         .id = GENL_ID_GENERATE,
 149         .hdrsize = 0,
 150         .name = "TCM-USER",
 151         .version = 1,
 152         .maxattr = TCMU_ATTR_MAX,
 153         .mcgrps = tcmu_mcgrps,
 154         .n_mcgrps = ARRAY_SIZE(tcmu_mcgrps),
 155 };
 156
 157 static struct tcmu_cmd *tcmu_alloc_cmd(struct se_cmd *se_cmd)
 158 {
 159         struct se_device *se_dev = se_cmd->se_dev;
 160         struct tcmu_dev *udev = TCMU_DEV(se_dev);
 161         struct tcmu_cmd *tcmu_cmd;
 162         int cmd_id;
 163
 164         tcmu_cmd = kmem_cache_zalloc(tcmu_cmd_cache, GFP_KERNEL);
 165         if (!tcmu_cmd)
 166                 return NULL;
 167
 168         tcmu_cmd->se_cmd = se_cmd;
 169         tcmu_cmd->tcmu_dev = udev;
 170         tcmu_cmd->data_length = se_cmd->data_length;
 171
 172         if (se_cmd->se_cmd_flags & SCF_BIDI) {
 173                 BUG_ON(!(se_cmd->t_bidi_data_sg && se_cmd->t_bidi_data_nents));
 174                 tcmu_cmd->data_length += se_cmd->t_bidi_data_sg->length;
 175         }
 176
 177         tcmu_cmd->deadline = jiffies + msecs_to_jiffies(TCMU_TIME_OUT);
 178
 179         idr_preload(GFP_KERNEL);
 180         spin_lock_irq(&udev->commands_lock);
 181         cmd_id = idr_alloc(&udev->commands, tcmu_cmd, 0,
 182                 USHRT_MAX, GFP_NOWAIT);
 183         spin_unlock_irq(&udev->commands_lock);
 184         idr_preload_end();
 185
 186         if (cmd_id < 0) {
 187                 kmem_cache_free(tcmu_cmd_cache, tcmu_cmd);
 188                 return NULL;
 189         }
 190         tcmu_cmd->cmd_id = cmd_id;
 191
 192         return tcmu_cmd;
 193 }
 194
 195 static inline void tcmu_flush_dcache_range(void *vaddr, size_t size)
 196 {
 197         unsigned long offset = (unsigned long) vaddr & ~PAGE_MASK;
 198
 199         size = round_up(size+offset, PAGE_SIZE);
 200         vaddr -= offset;
 201
 202         while (size) {
 203                 flush_dcache_page(virt_to_page(vaddr));
 204                 size -= PAGE_SIZE;
 205         }
 206 }
 207
 208 /*
 209  * Some ring helper functions. We don't assume size is a power of 2 so
 210  * we can't use circ_buf.h.
 211  */
 212 static inline size_t spc_used(size_t head, size_t tail, size_t size)
 213 {
 214         int diff = head - tail;
 215
 216         if (diff >= 0)
 217                 return diff;
 218         else
 219                 return size + diff;
 220 }
 221
 222 static inline size_t spc_free(size_t head, size_t tail, size_t size)
 223 {
 224         /* Keep 1 byte unused or we can't tell full from empty */
 225         return (size - spc_used(head, tail, size) - 1);
 226 }
 227
 228 static inline size_t head_to_end(size_t head, size_t size)
 229 {
 230         return size - head;
 231 }
 232
 233 #define UPDATE_HEAD(head, used, size) smp_store_release(&head, ((head % size) + used) % size)
 234
 235 static void alloc_and_scatter_data_area(struct tcmu_dev *udev,
 236         struct scatterlist *data_sg, unsigned int data_nents,
 237         struct iovec **iov, int *iov_cnt, bool copy_data)
 238 {
 239         int i;
 240         void *from, *to;
 241         size_t copy_bytes;
 242         struct scatterlist *sg;
 243
 244         for_each_sg(data_sg, sg, data_nents, i) {
 245                 copy_bytes = min_t(size_t, sg->length,
 246                                  head_to_end(udev->data_head, udev->data_size));
 247                 from = kmap_atomic(sg_page(sg)) + sg->offset;
 248                 to = (void *) udev->mb_addr + udev->data_off + udev->data_head;
 249
 250                 if (copy_data) {
 251                         memcpy(to, from, copy_bytes);
 252                         tcmu_flush_dcache_range(to, copy_bytes);
 253                 }
 254
 255                 /* Even iov_base is relative to mb_addr */
 256                 (*iov)->iov_len = copy_bytes;
 257                 (*iov)->iov_base = (void __user *) udev->data_off +
 258                                                 udev->data_head;
 259                 (*iov_cnt)++;
 260                 (*iov)++;
 261
 262                 UPDATE_HEAD(udev->data_head, copy_bytes, udev->data_size);
 263
 264                 /* Uh oh, we wrapped the buffer. Must split sg across 2 iovs. */
 265                 if (sg->length != copy_bytes) {
 266                         void *from_skip = from + copy_bytes;
 267
 268                         copy_bytes = sg->length - copy_bytes;
 269
 270                         (*iov)->iov_len = copy_bytes;
 271                         (*iov)->iov_base = (void __user *) udev->data_off +
 272                                                         udev->data_head;
 273
 274                         if (copy_data) {
 275                                 to = (void *) udev->mb_addr +
 276                                         udev->data_off + udev->data_head;
 277                                 memcpy(to, from_skip, copy_bytes);
 278                                 tcmu_flush_dcache_range(to, copy_bytes);
 279                         }
 280
 281                         (*iov_cnt)++;
 282                         (*iov)++;
 283
 284                         UPDATE_HEAD(udev->data_head,
 285                                 copy_bytes, udev->data_size);
 286                 }
 287
 288                 kunmap_atomic(from - sg->offset);
 289         }
 290 }
 291
 292 static void gather_and_free_data_area(struct tcmu_dev *udev,
 293         struct scatterlist *data_sg, unsigned int data_nents)
 294 {
 295         int i;
 296         void *from, *to;
 297         size_t copy_bytes;
 298         struct scatterlist *sg;
 299
 300         /* It'd be easier to look at entry's iovec again, but UAM */
 301         for_each_sg(data_sg, sg, data_nents, i) {
 302                 copy_bytes = min_t(size_t, sg->length,
 303                                  head_to_end(udev->data_tail, udev->data_size));
 304
 305                 to = kmap_atomic(sg_page(sg)) + sg->offset;
 306                 WARN_ON(sg->length + sg->offset > PAGE_SIZE);
 307                 from = (void *) udev->mb_addr +
 308                         udev->data_off + udev->data_tail;
 309                 tcmu_flush_dcache_range(from, copy_bytes);
 310                 memcpy(to, from, copy_bytes);
 311
 312                 UPDATE_HEAD(udev->data_tail, copy_bytes, udev->data_size);
 313
 314                 /* Uh oh, wrapped the data buffer for this sg's data */
 315                 if (sg->length != copy_bytes) {
 316                         void *to_skip = to + copy_bytes;
 317
 318                         from = (void *) udev->mb_addr +
 319                                 udev->data_off + udev->data_tail;
 320                         WARN_ON(udev->data_tail);
 321                         copy_bytes = sg->length - copy_bytes;
 322                         tcmu_flush_dcache_range(from, copy_bytes);
 323                         memcpy(to_skip, from, copy_bytes);
 324
 325                         UPDATE_HEAD(udev->data_tail,
 326                                 copy_bytes, udev->data_size);
 327                 }
 328                 kunmap_atomic(to - sg->offset);
 329         }
 330 }
 331
 332 /*
 333  * We can't queue a command until we have space available on the cmd ring *and*
 334  * space available on the data ring.
 335  *
 336  * Called with ring lock held.
 337  */
 338 static bool is_ring_space_avail(struct tcmu_dev *udev, size_t cmd_size, size_t data_needed)
 339 {
 340         struct tcmu_mailbox *mb = udev->mb_addr;
 341         size_t space;
 342         u32 cmd_head;
 343         size_t cmd_needed;
 344
 345         tcmu_flush_dcache_range(mb, sizeof(*mb));
 346
 347         cmd_head = mb->cmd_head % udev->cmdr_size; /* UAM */
 348
 349         /*
 350          * If cmd end-of-ring space is too small then we need space for a NOP plus
 351          * original cmd - cmds are internally contiguous.
 352          */
 353         if (head_to_end(cmd_head, udev->cmdr_size) >= cmd_size)
 354                 cmd_needed = cmd_size;
 355         else
 356                 cmd_needed = cmd_size + head_to_end(cmd_head, udev->cmdr_size);
 357
 358         space = spc_free(cmd_head, udev->cmdr_last_cleaned, udev->cmdr_size);
 359         if (space < cmd_needed) {
 360                 pr_debug("no cmd space: %u %u %u\n", cmd_head,
 361                        udev->cmdr_last_cleaned, udev->cmdr_size);
 362                 return false;
 363         }
 364
 365         space = spc_free(udev->data_head, udev->data_tail, udev->data_size);
 366         if (space < data_needed) {
 367                 pr_debug("no data space: %zu %zu %zu\n", udev->data_head,
 368                        udev->data_tail, udev->data_size);
 369                 return false;
 370         }
 371
 372         return true;
 373 }
 374
 375 static int tcmu_queue_cmd_ring(struct tcmu_cmd *tcmu_cmd)
 376 {
 377         struct tcmu_dev *udev = tcmu_cmd->tcmu_dev;
 378         struct se_cmd *se_cmd = tcmu_cmd->se_cmd;
 379         size_t base_command_size, command_size;
 380         struct tcmu_mailbox *mb;
 381         struct tcmu_cmd_entry *entry;
 382         struct iovec *iov;
 383         int iov_cnt;
 384         uint32_t cmd_head;
 385         uint64_t cdb_off;
 386         bool copy_to_data_area;
 387
 388         if (test_bit(TCMU_DEV_BIT_BROKEN, &udev->flags))
 389                 return -EINVAL;
 390
 391         /*
 392          * Must be a certain minimum size for response sense info, but
 393          * also may be larger if the iov array is large.
 394          *
 395          * iovs = sgl_nents+1, for end-of-ring case, plus another 1
 396          * b/c size == offsetof one-past-element.
 397         */
 398         base_command_size = max(offsetof(struct tcmu_cmd_entry,
 399                                          req.iov[se_cmd->t_bidi_data_nents +
 400                                                  se_cmd->t_data_nents + 2]),
 401                                 sizeof(struct tcmu_cmd_entry));
 402         command_size = base_command_size
 403                 + round_up(scsi_command_size(se_cmd->t_task_cdb), TCMU_OP_ALIGN_SIZE);
 404
 405         WARN_ON(command_size & (TCMU_OP_ALIGN_SIZE-1));
 406
 407         spin_lock_irq(&udev->cmdr_lock);
 408
 409         mb = udev->mb_addr;
 410         cmd_head = mb->cmd_head % udev->cmdr_size; /* UAM */
 411         if ((command_size > (udev->cmdr_size / 2))
 412             || tcmu_cmd->data_length > (udev->data_size - 1))
 413                 pr_warn("TCMU: Request of size %zu/%zu may be too big for %u/%zu "
 414                         "cmd/data ring buffers\n", command_size, tcmu_cmd->data_length,
 415                         udev->cmdr_size, udev->data_size);
 416
 417         while (!is_ring_space_avail(udev, command_size, tcmu_cmd->data_length)) {
 418                 int ret;
 419                 DEFINE_WAIT(__wait);
 420
 421                 prepare_to_wait(&udev->wait_cmdr, &__wait, TASK_INTERRUPTIBLE);
 422
 423                 pr_debug("sleeping for ring space\n");
 424                 spin_unlock_irq(&udev->cmdr_lock);
 425                 ret = schedule_timeout(msecs_to_jiffies(TCMU_TIME_OUT));
 426                 finish_wait(&udev->wait_cmdr, &__wait);
 427                 if (!ret) {
 428                         pr_warn("tcmu: command timed out\n");
 429                         return -ETIMEDOUT;
 430                 }
 431
 432                 spin_lock_irq(&udev->cmdr_lock);
 433
 434                 /* We dropped cmdr_lock, cmd_head is stale */
 435                 cmd_head = mb->cmd_head % udev->cmdr_size; /* UAM */
 436         }
 437
 438         /* Insert a PAD if end-of-ring space is too small */
 439         if (head_to_end(cmd_head, udev->cmdr_size) < command_size) {
 440                 size_t pad_size = head_to_end(cmd_head, udev->cmdr_size);
 441
 442                 entry = (void *) mb + CMDR_OFF + cmd_head;
 443                 tcmu_flush_dcache_range(entry, sizeof(*entry));
 444                 tcmu_hdr_set_op(&entry->hdr.len_op, TCMU_OP_PAD);
 445                 tcmu_hdr_set_len(&entry->hdr.len_op, pad_size);
 446                 entry->hdr.cmd_id = 0; /* not used for PAD */
 447                 entry->hdr.kflags = 0;
 448                 entry->hdr.uflags = 0;
 449
 450                 UPDATE_HEAD(mb->cmd_head, pad_size, udev->cmdr_size);
 451
 452                 cmd_head = mb->cmd_head % udev->cmdr_size; /* UAM */
 453                 WARN_ON(cmd_head != 0);
 454         }
 455
 456         entry = (void *) mb + CMDR_OFF + cmd_head;
 457         tcmu_flush_dcache_range(entry, sizeof(*entry));
 458         tcmu_hdr_set_op(&entry->hdr.len_op, TCMU_OP_CMD);
 459         tcmu_hdr_set_len(&entry->hdr.len_op, command_size);
 460         entry->hdr.cmd_id = tcmu_cmd->cmd_id;
 461         entry->hdr.kflags = 0;
 462         entry->hdr.uflags = 0;
 463
 464         /*
 465          * Fix up iovecs, and handle if allocation in data ring wrapped.
 466          */
 467         iov = &entry->req.iov[0];
 468         iov_cnt = 0;
 469         copy_to_data_area = (se_cmd->data_direction == DMA_TO_DEVICE
 470                 || se_cmd->se_cmd_flags & SCF_BIDI);
 471         alloc_and_scatter_data_area(udev, se_cmd->t_data_sg,
 472                 se_cmd->t_data_nents, &iov, &iov_cnt, copy_to_data_area);
 473         entry->req.iov_cnt = iov_cnt;
 474         entry->req.iov_dif_cnt = 0;
 475
 476         /* Handle BIDI commands */
 477         iov_cnt = 0;
 478         alloc_and_scatter_data_area(udev, se_cmd->t_bidi_data_sg,
 479                 se_cmd->t_bidi_data_nents, &iov, &iov_cnt, false);
 480         entry->req.iov_bidi_cnt = iov_cnt;
 481
 482         /* All offsets relative to mb_addr, not start of entry! */
 483         cdb_off = CMDR_OFF + cmd_head + base_command_size;
 484         memcpy((void *) mb + cdb_off, se_cmd->t_task_cdb, scsi_command_size(se_cmd->t_task_cdb));
 485         entry->req.cdb_off = cdb_off;
 486         tcmu_flush_dcache_range(entry, sizeof(*entry));
 487
 488         UPDATE_HEAD(mb->cmd_head, command_size, udev->cmdr_size);
 489         tcmu_flush_dcache_range(mb, sizeof(*mb));
 490
 491         spin_unlock_irq(&udev->cmdr_lock);
 492
 493         /* TODO: only if FLUSH and FUA? */
 494         uio_event_notify(&udev->uio_info);
 495
 496         mod_timer(&udev->timeout,
 497                 round_jiffies_up(jiffies + msecs_to_jiffies(TCMU_TIME_OUT)));
 498
 499         return 0;
 500 }
 501
 502 static int tcmu_queue_cmd(struct se_cmd *se_cmd)
 503 {
 504         struct se_device *se_dev = se_cmd->se_dev;
 505         struct tcmu_dev *udev = TCMU_DEV(se_dev);
 506         struct tcmu_cmd *tcmu_cmd;
 507         int ret;
 508
 509         tcmu_cmd = tcmu_alloc_cmd(se_cmd);
 510         if (!tcmu_cmd)
 511                 return -ENOMEM;
 512
 513         ret = tcmu_queue_cmd_ring(tcmu_cmd);
 514         if (ret < 0) {
 515                 pr_err("TCMU: Could not queue command\n");
 516                 spin_lock_irq(&udev->commands_lock);
 517                 idr_remove(&udev->commands, tcmu_cmd->cmd_id);
 518                 spin_unlock_irq(&udev->commands_lock);
 519
 520                 kmem_cache_free(tcmu_cmd_cache, tcmu_cmd);
 521         }
 522
 523         return ret;
 524 }
 525
 526 static void tcmu_handle_completion(struct tcmu_cmd *cmd, struct tcmu_cmd_entry *entry)
 527 {
 528         struct se_cmd *se_cmd = cmd->se_cmd;
 529         struct tcmu_dev *udev = cmd->tcmu_dev;
 530
 531         if (test_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags)) {
 532                 /* cmd has been completed already from timeout, just reclaim data
 533                    ring space */
 534                 UPDATE_HEAD(udev->data_tail, cmd->data_length, udev->data_size);
 535                 return;
 536         }
 537
 538         if (entry->hdr.uflags & TCMU_UFLAG_UNKNOWN_OP) {
 539                 UPDATE_HEAD(udev->data_tail, cmd->data_length, udev->data_size);
 540                 pr_warn("TCMU: Userspace set UNKNOWN_OP flag on se_cmd %p\n",
 541                         cmd->se_cmd);
 542                 entry->rsp.scsi_status = SAM_STAT_CHECK_CONDITION;
 543         } else if (entry->rsp.scsi_status == SAM_STAT_CHECK_CONDITION) {
 544                 memcpy(se_cmd->sense_buffer, entry->rsp.sense_buffer,
 545                                se_cmd->scsi_sense_length);
 546
 547                 UPDATE_HEAD(udev->data_tail, cmd->data_length, udev->data_size);
 548         } else if (se_cmd->se_cmd_flags & SCF_BIDI) {
 549                 /* Discard data_out buffer */
 550                 UPDATE_HEAD(udev->data_tail,
 551                         (size_t)se_cmd->t_data_sg->length, udev->data_size);
 552
 553                 /* Get Data-In buffer */
 554                 gather_and_free_data_area(udev,
 555                         se_cmd->t_bidi_data_sg, se_cmd->t_bidi_data_nents);
 556         } else if (se_cmd->data_direction == DMA_FROM_DEVICE) {
 557                 gather_and_free_data_area(udev,
 558                         se_cmd->t_data_sg, se_cmd->t_data_nents);
 559         } else if (se_cmd->data_direction == DMA_TO_DEVICE) {
 560                 UPDATE_HEAD(udev->data_tail, cmd->data_length, udev->data_size);
 561         } else if (se_cmd->data_direction != DMA_NONE) {
 562                 pr_warn("TCMU: data direction was %d!\n",
 563                         se_cmd->data_direction);
 564         }
 565
 566         target_complete_cmd(cmd->se_cmd, entry->rsp.scsi_status);
 567         cmd->se_cmd = NULL;
 568
 569         kmem_cache_free(tcmu_cmd_cache, cmd);
 570 }
 571
 572 static unsigned int tcmu_handle_completions(struct tcmu_dev *udev)
 573 {
 574         struct tcmu_mailbox *mb;
 575         unsigned long flags;
 576         int handled = 0;
 577
 578         if (test_bit(TCMU_DEV_BIT_BROKEN, &udev->flags)) {
 579                 pr_err("ring broken, not handling completions\n");
 580                 return 0;
 581         }
 582
 583         spin_lock_irqsave(&udev->cmdr_lock, flags);
 584
 585         mb = udev->mb_addr;
 586         tcmu_flush_dcache_range(mb, sizeof(*mb));
 587
 588         while (udev->cmdr_last_cleaned != ACCESS_ONCE(mb->cmd_tail)) {
 589
 590                 struct tcmu_cmd_entry *entry = (void *) mb + CMDR_OFF + udev->cmdr_last_cleaned;
 591                 struct tcmu_cmd *cmd;
 592
 593                 tcmu_flush_dcache_range(entry, sizeof(*entry));
 594
 595                 if (tcmu_hdr_get_op(entry->hdr.len_op) == TCMU_OP_PAD) {
 596                         UPDATE_HEAD(udev->cmdr_last_cleaned,
 597                                     tcmu_hdr_get_len(entry->hdr.len_op),
 598                                     udev->cmdr_size);
 599                         continue;
 600                 }
 601                 WARN_ON(tcmu_hdr_get_op(entry->hdr.len_op) != TCMU_OP_CMD);
 602
 603                 spin_lock(&udev->commands_lock);
 604                 cmd = idr_find(&udev->commands, entry->hdr.cmd_id);
 605                 if (cmd)
 606                         idr_remove(&udev->commands, cmd->cmd_id);
 607                 spin_unlock(&udev->commands_lock);
 608
 609                 if (!cmd) {
 610                         pr_err("cmd_id not found, ring is broken\n");
 611                         set_bit(TCMU_DEV_BIT_BROKEN, &udev->flags);
 612                         break;
 613                 }
 614
 615                 tcmu_handle_completion(cmd, entry);
 616
 617                 UPDATE_HEAD(udev->cmdr_last_cleaned,
 618                             tcmu_hdr_get_len(entry->hdr.len_op),
 619                             udev->cmdr_size);
 620
 621                 handled++;
 622         }
 623
 624         if (mb->cmd_tail == mb->cmd_head)
 625                 del_timer(&udev->timeout); /* no more pending cmds */
 626
 627         spin_unlock_irqrestore(&udev->cmdr_lock, flags);
 628
 629         wake_up(&udev->wait_cmdr);
 630
 631         return handled;
 632 }
 633
 634 static int tcmu_check_expired_cmd(int id, void *p, void *data)
 635 {
 636         struct tcmu_cmd *cmd = p;
 637
 638         if (test_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags))
 639                 return 0;
 640
 641         if (!time_after(jiffies, cmd->deadline))
 642                 return 0;
 643
 644         set_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags);
 645         target_complete_cmd(cmd->se_cmd, SAM_STAT_CHECK_CONDITION);
 646         cmd->se_cmd = NULL;
 647
 648         return 0;
 649 }
 650
 651 static void tcmu_device_timedout(unsigned long data)
 652 {
 653         struct tcmu_dev *udev = (struct tcmu_dev *)data;
 654         unsigned long flags;
 655         int handled;
 656
 657         handled = tcmu_handle_completions(udev);
 658
 659         pr_warn("%d completions handled from timeout\n", handled);
 660
 661         spin_lock_irqsave(&udev->commands_lock, flags);
 662         idr_for_each(&udev->commands, tcmu_check_expired_cmd, NULL);
 663         spin_unlock_irqrestore(&udev->commands_lock, flags);
 664
 665         /*
 666          * We don't need to wakeup threads on wait_cmdr since they have their
 667          * own timeout.
 668          */
 669 }
 670
 671 static int tcmu_attach_hba(struct se_hba *hba, u32 host_id)
 672 {
 673         struct tcmu_hba *tcmu_hba;
 674
 675         tcmu_hba = kzalloc(sizeof(struct tcmu_hba), GFP_KERNEL);
 676         if (!tcmu_hba)
 677                 return -ENOMEM;
 678
 679         tcmu_hba->host_id = host_id;
 680         hba->hba_ptr = tcmu_hba;
 681
 682         return 0;
 683 }
 684
 685 static void tcmu_detach_hba(struct se_hba *hba)
 686 {
 687         kfree(hba->hba_ptr);
 688         hba->hba_ptr = NULL;
 689 }
 690
 691 static struct se_device *tcmu_alloc_device(struct se_hba *hba, const char *name)
 692 {
 693         struct tcmu_dev *udev;
 694
 695         udev = kzalloc(sizeof(struct tcmu_dev), GFP_KERNEL);
 696         if (!udev)
 697                 return NULL;
 698
 699         udev->name = kstrdup(name, GFP_KERNEL);
 700         if (!udev->name) {
 701                 kfree(udev);
 702                 return NULL;
 703         }
 704
 705         udev->hba = hba;
 706
 707         init_waitqueue_head(&udev->wait_cmdr);
 708         spin_lock_init(&udev->cmdr_lock);
 709
 710         idr_init(&udev->commands);
 711         spin_lock_init(&udev->commands_lock);
 712
 713         setup_timer(&udev->timeout, tcmu_device_timedout,
 714                 (unsigned long)udev);
 715
 716         return &udev->se_dev;
 717 }
 718
 719 static int tcmu_irqcontrol(struct uio_info *info, s32 irq_on)
 720 {
 721         struct tcmu_dev *tcmu_dev = container_of(info, struct tcmu_dev, uio_info);
 722
 723         tcmu_handle_completions(tcmu_dev);
 724
 725         return 0;
 726 }
 727
 728 /*
 729  * mmap code from uio.c. Copied here because we want to hook mmap()
 730  * and this stuff must come along.
 731  */
 732 static int tcmu_find_mem_index(struct vm_area_struct *vma)
 733 {
 734         struct tcmu_dev *udev = vma->vm_private_data;
 735         struct uio_info *info = &udev->uio_info;
 736
 737         if (vma->vm_pgoff < MAX_UIO_MAPS) {
 738                 if (info->mem[vma->vm_pgoff].size == 0)
 739                         return -1;
 740                 return (int)vma->vm_pgoff;
 741         }
 742         return -1;
 743 }
 744
 745 static int tcmu_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 746 {
 747         struct tcmu_dev *udev = vma->vm_private_data;
 748         struct uio_info *info = &udev->uio_info;
 749         struct page *page;
 750         unsigned long offset;
 751         void *addr;
 752
 753         int mi = tcmu_find_mem_index(vma);
 754         if (mi < 0)
 755                 return VM_FAULT_SIGBUS;
 756
 757         /*
 758          * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
 759          * to use mem[N].
 760          */
 761         offset = (vmf->pgoff - mi) << PAGE_SHIFT;
 762
 763         addr = (void *)(unsigned long)info->mem[mi].addr + offset;
 764         if (info->mem[mi].memtype == UIO_MEM_LOGICAL)
 765                 page = virt_to_page(addr);
 766         else
 767                 page = vmalloc_to_page(addr);
 768         get_page(page);
 769         vmf->page = page;
 770         return 0;
 771 }
 772
 773 static const struct vm_operations_struct tcmu_vm_ops = {
 774         .fault = tcmu_vma_fault,
 775 };
 776
 777 static int tcmu_mmap(struct uio_info *info, struct vm_area_struct *vma)
 778 {
 779         struct tcmu_dev *udev = container_of(info, struct tcmu_dev, uio_info);
 780
 781         vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
 782         vma->vm_ops = &tcmu_vm_ops;
 783
 784         vma->vm_private_data = udev;
 785
 786         /* Ensure the mmap is exactly the right size */
 787         if (vma_pages(vma) != (TCMU_RING_SIZE >> PAGE_SHIFT))
 788                 return -EINVAL;
 789
 790         return 0;
 791 }
 792
 793 static int tcmu_open(struct uio_info *info, struct inode *inode)
 794 {
 795         struct tcmu_dev *udev = container_of(info, struct tcmu_dev, uio_info);
 796
 797         /* O_EXCL not supported for char devs, so fake it? */
 798         if (test_and_set_bit(TCMU_DEV_BIT_OPEN, &udev->flags))
 799                 return -EBUSY;
 800
 801         pr_debug("open\n");
 802
 803         return 0;
 804 }
 805
 806 static int tcmu_release(struct uio_info *info, struct inode *inode)
 807 {
 808         struct tcmu_dev *udev = container_of(info, struct tcmu_dev, uio_info);
 809
 810         clear_bit(TCMU_DEV_BIT_OPEN, &udev->flags);
 811
 812         pr_debug("close\n");
 813
 814         return 0;
 815 }
 816
 817 static int tcmu_netlink_event(enum tcmu_genl_cmd cmd, const char *name, int minor)
 818 {
 819         struct sk_buff *skb;
 820         void *msg_header;
 821         int ret = -ENOMEM;
 822
 823         skb = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
 824         if (!skb)
 825                 return ret;
 826
 827         msg_header = genlmsg_put(skb, 0, 0, &tcmu_genl_family, 0, cmd);
 828         if (!msg_header)
 829                 goto free_skb;
 830
 831         ret = nla_put_string(skb, TCMU_ATTR_DEVICE, name);
 832         if (ret < 0)
 833                 goto free_skb;
 834
 835         ret = nla_put_u32(skb, TCMU_ATTR_MINOR, minor);
 836         if (ret < 0)
 837                 goto free_skb;
 838
 839         genlmsg_end(skb, msg_header);
 840
 841         ret = genlmsg_multicast(&tcmu_genl_family, skb, 0,
 842                                 TCMU_MCGRP_CONFIG, GFP_KERNEL);
 843
 844         /* We don't care if no one is listening */
 845         if (ret == -ESRCH)
 846                 ret = 0;
 847
 848         return ret;
 849 free_skb:
 850         nlmsg_free(skb);
 851         return ret;
 852 }
 853
 854 static int tcmu_configure_device(struct se_device *dev)
 855 {
 856         struct tcmu_dev *udev = TCMU_DEV(dev);
 857         struct tcmu_hba *hba = udev->hba->hba_ptr;
 858         struct uio_info *info;
 859         struct tcmu_mailbox *mb;
 860         size_t size;
 861         size_t used;
 862         int ret = 0;
 863         char *str;
 864
 865         info = &udev->uio_info;
 866
 867         size = snprintf(NULL, 0, "tcm-user/%u/%s/%s", hba->host_id, udev->name,
 868                         udev->dev_config);
 869         size += 1; /* for \0 */
 870         str = kmalloc(size, GFP_KERNEL);
 871         if (!str)
 872                 return -ENOMEM;
 873
 874         used = snprintf(str, size, "tcm-user/%u/%s", hba->host_id, udev->name);
 875
 876         if (udev->dev_config[0])
 877                 snprintf(str + used, size - used, "/%s", udev->dev_config);
 878
 879         info->name = str;
 880
 881         udev->mb_addr = vzalloc(TCMU_RING_SIZE);
 882         if (!udev->mb_addr) {
 883                 ret = -ENOMEM;
 884                 goto err_vzalloc;
 885         }
 886
 887         /* mailbox fits in first part of CMDR space */
 888         udev->cmdr_size = CMDR_SIZE - CMDR_OFF;
 889         udev->data_off = CMDR_SIZE;
 890         udev->data_size = TCMU_RING_SIZE - CMDR_SIZE;
 891
 892         mb = udev->mb_addr;
 893         mb->version = TCMU_MAILBOX_VERSION;
 894         mb->cmdr_off = CMDR_OFF;
 895         mb->cmdr_size = udev->cmdr_size;
 896
 897         WARN_ON(!PAGE_ALIGNED(udev->data_off));
 898         WARN_ON(udev->data_size % PAGE_SIZE);
 899
 900         info->version = __stringify(TCMU_MAILBOX_VERSION);
 901
 902         info->mem[0].name = "tcm-user command & data buffer";
 903         info->mem[0].addr = (phys_addr_t) udev->mb_addr;
 904         info->mem[0].size = TCMU_RING_SIZE;
 905         info->mem[0].memtype = UIO_MEM_VIRTUAL;
 906
 907         info->irqcontrol = tcmu_irqcontrol;
 908         info->irq = UIO_IRQ_CUSTOM;
 909
 910         info->mmap = tcmu_mmap;
 911         info->open = tcmu_open;
 912         info->release = tcmu_release;
 913
 914         ret = uio_register_device(tcmu_root_device, info);
 915         if (ret)
 916                 goto err_register;
 917
 918         /* Other attributes can be configured in userspace */
 919         dev->dev_attrib.hw_block_size = 512;
 920         dev->dev_attrib.hw_max_sectors = 128;
 921         dev->dev_attrib.hw_queue_depth = 128;
 922
 923         ret = tcmu_netlink_event(TCMU_CMD_ADDED_DEVICE, udev->uio_info.name,
 924                                  udev->uio_info.uio_dev->minor);
 925         if (ret)
 926                 goto err_netlink;
 927
 928         return 0;
 929
 930 err_netlink:
 931         uio_unregister_device(&udev->uio_info);
 932 err_register:
 933         vfree(udev->mb_addr);
 934 err_vzalloc:
 935         kfree(info->name);
 936
 937         return ret;
 938 }
 939
 940 static int tcmu_check_pending_cmd(int id, void *p, void *data)
 941 {
 942         struct tcmu_cmd *cmd = p;
 943
 944         if (test_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags))
 945                 return 0;
 946         return -EINVAL;
 947 }
 948
 949 static void tcmu_dev_call_rcu(struct rcu_head *p)
 950 {
 951         struct se_device *dev = container_of(p, struct se_device, rcu_head);
 952         struct tcmu_dev *udev = TCMU_DEV(dev);
 953
 954         kfree(udev);
 955 }
 956
 957 static void tcmu_free_device(struct se_device *dev)
 958 {
 959         struct tcmu_dev *udev = TCMU_DEV(dev);
 960         int i;
 961
 962         del_timer_sync(&udev->timeout);
 963
 964         vfree(udev->mb_addr);
 965
 966         /* Upper layer should drain all requests before calling this */
 967         spin_lock_irq(&udev->commands_lock);
 968         i = idr_for_each(&udev->commands, tcmu_check_pending_cmd, NULL);
 969         idr_destroy(&udev->commands);
 970         spin_unlock_irq(&udev->commands_lock);
 971         WARN_ON(i);
 972
 973         /* Device was configured */
 974         if (udev->uio_info.uio_dev) {
 975                 tcmu_netlink_event(TCMU_CMD_REMOVED_DEVICE, udev->uio_info.name,
 976                                    udev->uio_info.uio_dev->minor);
 977
 978                 uio_unregister_device(&udev->uio_info);
 979                 kfree(udev->uio_info.name);
 980                 kfree(udev->name);
 981         }
 982         call_rcu(&dev->rcu_head, tcmu_dev_call_rcu);
 983 }
 984
 985 enum {
 986         Opt_dev_config, Opt_dev_size, Opt_hw_block_size, Opt_err,
 987 };
 988
 989 static match_table_t tokens = {
 990         {Opt_dev_config, "dev_config=%s"},
 991         {Opt_dev_size, "dev_size=%u"},
 992         {Opt_hw_block_size, "hw_block_size=%u"},
 993         {Opt_err, NULL}
 994 };
 995
 996 static ssize_t tcmu_set_configfs_dev_params(struct se_device *dev,
 997                 const char *page, ssize_t count)
 998 {
 999         struct tcmu_dev *udev = TCMU_DEV(dev);
1000         char *orig, *ptr, *opts, *arg_p;
1001         substring_t args[MAX_OPT_ARGS];
1002         int ret = 0, token;
1003         unsigned long tmp_ul;
1004
1005         opts = kstrdup(page, GFP_KERNEL);
1006         if (!opts)
1007                 return -ENOMEM;
1008
1009         orig = opts;
1010
1011         while ((ptr = strsep(&opts, ",\n")) != NULL) {
1012                 if (!*ptr)
1013                         continue;
1014
1015                 token = match_token(ptr, tokens, args);
1016                 switch (token) {
1017                 case Opt_dev_config:
1018                         if (match_strlcpy(udev->dev_config, &args[0],
1019                                           TCMU_CONFIG_LEN) == 0) {
1020                                 ret = -EINVAL;
1021                                 break;
1022                         }
1023                         pr_debug("TCMU: Referencing Path: %s\n", udev->dev_config);
1024                         break;
1025                 case Opt_dev_size:
1026                         arg_p = match_strdup(&args[0]);
1027                         if (!arg_p) {
1028                                 ret = -ENOMEM;
1029                                 break;
1030                         }
1031                         ret = kstrtoul(arg_p, 0, (unsigned long *) &udev->dev_size);
1032                         kfree(arg_p);
1033                         if (ret < 0)
1034                                 pr_err("kstrtoul() failed for dev_size=\n");
1035                         break;
1036                 case Opt_hw_block_size:
1037                         arg_p = match_strdup(&args[0]);
1038                         if (!arg_p) {
1039                                 ret = -ENOMEM;
1040                                 break;
1041                         }
1042                         ret = kstrtoul(arg_p, 0, &tmp_ul);
1043                         kfree(arg_p);
1044                         if (ret < 0) {
1045                                 pr_err("kstrtoul() failed for hw_block_size=\n");
1046                                 break;
1047                         }
1048                         if (!tmp_ul) {
1049                                 pr_err("hw_block_size must be nonzero\n");
1050                                 break;
1051                         }
1052                         dev->dev_attrib.hw_block_size = tmp_ul;
1053                         break;
1054                 default:
1055                         break;
1056                 }
1057         }
1058
1059         kfree(orig);
1060         return (!ret) ? count : ret;
1061 }
1062
1063 static ssize_t tcmu_show_configfs_dev_params(struct se_device *dev, char *b)
1064 {
1065         struct tcmu_dev *udev = TCMU_DEV(dev);
1066         ssize_t bl = 0;
1067
1068         bl = sprintf(b + bl, "Config: %s ",
1069                      udev->dev_config[0] ? udev->dev_config : "NULL");
1070         bl += sprintf(b + bl, "Size: %zu\n", udev->dev_size);
1071
1072         return bl;
1073 }
1074
1075 static sector_t tcmu_get_blocks(struct se_device *dev)
1076 {
1077         struct tcmu_dev *udev = TCMU_DEV(dev);
1078
1079         return div_u64(udev->dev_size - dev->dev_attrib.block_size,
1080                        dev->dev_attrib.block_size);
1081 }
1082
1083 static sense_reason_t
1084 tcmu_pass_op(struct se_cmd *se_cmd)
1085 {
1086         int ret = tcmu_queue_cmd(se_cmd);
1087
1088         if (ret != 0)
1089                 return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
1090         else
1091                 return TCM_NO_SENSE;
1092 }
1093
1094 static sense_reason_t
1095 tcmu_parse_cdb(struct se_cmd *cmd)
1096 {
1097         return passthrough_parse_cdb(cmd, tcmu_pass_op);
1098 }
1099
1100 static const struct target_backend_ops tcmu_ops = {
1101         .name                   = "user",
1102         .owner                  = THIS_MODULE,
1103         .transport_flags        = TRANSPORT_FLAG_PASSTHROUGH,
1104         .attach_hba             = tcmu_attach_hba,
1105         .detach_hba             = tcmu_detach_hba,
1106         .alloc_device           = tcmu_alloc_device,
1107         .configure_device       = tcmu_configure_device,
1108         .free_device            = tcmu_free_device,
1109         .parse_cdb              = tcmu_parse_cdb,
1110         .set_configfs_dev_params = tcmu_set_configfs_dev_params,
1111         .show_configfs_dev_params = tcmu_show_configfs_dev_params,
1112         .get_device_type        = sbc_get_device_type,
1113         .get_blocks             = tcmu_get_blocks,
1114         .tb_dev_attrib_attrs    = passthrough_attrib_attrs,
1115 };
1116
1117 static int __init tcmu_module_init(void)
1118 {
1119         int ret;
1120
1121         BUILD_BUG_ON((sizeof(struct tcmu_cmd_entry) % TCMU_OP_ALIGN_SIZE) != 0);
1122
1123         tcmu_cmd_cache = kmem_cache_create("tcmu_cmd_cache",
1124                                 sizeof(struct tcmu_cmd),
1125                                 __alignof__(struct tcmu_cmd),
1126                                 0, NULL);
1127         if (!tcmu_cmd_cache)
1128                 return -ENOMEM;
1129
1130         tcmu_root_device = root_device_register("tcm_user");
1131         if (IS_ERR(tcmu_root_device)) {
1132                 ret = PTR_ERR(tcmu_root_device);
1133                 goto out_free_cache;
1134         }
1135
1136         ret = genl_register_family(&tcmu_genl_family);
1137         if (ret < 0) {
1138                 goto out_unreg_device;
1139         }
1140
1141         ret = transport_backend_register(&tcmu_ops);
1142         if (ret)
1143                 goto out_unreg_genl;
1144
1145         return 0;
1146
1147 out_unreg_genl:
1148         genl_unregister_family(&tcmu_genl_family);
1149 out_unreg_device:
1150         root_device_unregister(tcmu_root_device);
1151 out_free_cache:
1152         kmem_cache_destroy(tcmu_cmd_cache);
1153
1154         return ret;
1155 }
1156
1157 static void __exit tcmu_module_exit(void)
1158 {
1159         target_backend_unregister(&tcmu_ops);
1160         genl_unregister_family(&tcmu_genl_family);
1161         root_device_unregister(tcmu_root_device);
1162         kmem_cache_destroy(tcmu_cmd_cache);
1163 }
1164
1165 MODULE_DESCRIPTION("TCM USER subsystem plugin");
1166 MODULE_AUTHOR("Shaohua Li <shli@kernel.org>");
1167 MODULE_AUTHOR("Andy Grover <agrover@redhat.com>");
1168 MODULE_LICENSE("GPL");
1169
1170 module_init(tcmu_module_init);
1171 module_exit(tcmu_module_exit);