drivers/xen/xen-pciback/conf_space.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * PCI Backend - Functions for creating a virtual configuration space for
   4  *               exported PCI Devices.
   5  *               It's dangerous to allow PCI Driver Domains to change their
   6  *               device's resources (memory, i/o ports, interrupts). We need to
   7  *               restrict changes to certain PCI Configuration registers:
   8  *               BARs, INTERRUPT_PIN, most registers in the header...
   9  *
  10  * Author: Ryan Wilson <hap9@epoch.ncsc.mil>
  11  */
  12
  13 #define dev_fmt(fmt) DRV_NAME ": " fmt
  14
  15 #include <linux/kernel.h>
  16 #include <linux/moduleparam.h>
  17 #include <linux/pci.h>
  18 #include "pciback.h"
  19 #include "conf_space.h"
  20 #include "conf_space_quirks.h"
  21
  22 bool xen_pcibk_permissive;
  23 module_param_named(permissive, xen_pcibk_permissive, bool, 0644);
  24
  25 /* This is where xen_pcibk_read_config_byte, xen_pcibk_read_config_word,
  26  * xen_pcibk_write_config_word, and xen_pcibk_write_config_byte are created. */
  27 #define DEFINE_PCI_CONFIG(op, size, type)                       \
  28 int xen_pcibk_##op##_config_##size                              \
  29 (struct pci_dev *dev, int offset, type value, void *data)       \
  30 {                                                               \
  31         return pci_##op##_config_##size(dev, offset, value);    \
  32 }
  33
  34 DEFINE_PCI_CONFIG(read, byte, u8 *)
  35 DEFINE_PCI_CONFIG(read, word, u16 *)
  36 DEFINE_PCI_CONFIG(read, dword, u32 *)
  37
  38 DEFINE_PCI_CONFIG(write, byte, u8)
  39 DEFINE_PCI_CONFIG(write, word, u16)
  40 DEFINE_PCI_CONFIG(write, dword, u32)
  41
  42 static int conf_space_read(struct pci_dev *dev,
  43                            const struct config_field_entry *entry,
  44                            int offset, u32 *value)
  45 {
  46         int ret = 0;
  47         const struct config_field *field = entry->field;
  48
  49         *value = 0;
  50
  51         switch (field->size) {
  52         case 1:
  53                 if (field->u.b.read)
  54                         ret = field->u.b.read(dev, offset, (u8 *) value,
  55                                               entry->data);
  56                 break;
  57         case 2:
  58                 if (field->u.w.read)
  59                         ret = field->u.w.read(dev, offset, (u16 *) value,
  60                                               entry->data);
  61                 break;
  62         case 4:
  63                 if (field->u.dw.read)
  64                         ret = field->u.dw.read(dev, offset, value, entry->data);
  65                 break;
  66         }
  67         return ret;
  68 }
  69
  70 static int conf_space_write(struct pci_dev *dev,
  71                             const struct config_field_entry *entry,
  72                             int offset, u32 value)
  73 {
  74         int ret = 0;
  75         const struct config_field *field = entry->field;
  76
  77         switch (field->size) {
  78         case 1:
  79                 if (field->u.b.write)
  80                         ret = field->u.b.write(dev, offset, (u8) value,
  81                                                entry->data);
  82                 break;
  83         case 2:
  84                 if (field->u.w.write)
  85                         ret = field->u.w.write(dev, offset, (u16) value,
  86                                                entry->data);
  87                 break;
  88         case 4:
  89                 if (field->u.dw.write)
  90                         ret = field->u.dw.write(dev, offset, value,
  91                                                 entry->data);
  92                 break;
  93         }
  94         return ret;
  95 }
  96
  97 static inline u32 get_mask(int size)
  98 {
  99         if (size == 1)
 100                 return 0xff;
 101         else if (size == 2)
 102                 return 0xffff;
 103         else
 104                 return 0xffffffff;
 105 }
 106
 107 static inline int valid_request(int offset, int size)
 108 {
 109         /* Validate request (no un-aligned requests) */
 110         if ((size == 1 || size == 2 || size == 4) && (offset % size) == 0)
 111                 return 1;
 112         return 0;
 113 }
 114
 115 static inline u32 merge_value(u32 val, u32 new_val, u32 new_val_mask,
 116                               int offset)
 117 {
 118         if (offset >= 0) {
 119                 new_val_mask <<= (offset * 8);
 120                 new_val <<= (offset * 8);
 121         } else {
 122                 new_val_mask >>= (offset * -8);
 123                 new_val >>= (offset * -8);
 124         }
 125         val = (val & ~new_val_mask) | (new_val & new_val_mask);
 126
 127         return val;
 128 }
 129
 130 static int xen_pcibios_err_to_errno(int err)
 131 {
 132         switch (err) {
 133         case PCIBIOS_SUCCESSFUL:
 134                 return XEN_PCI_ERR_success;
 135         case PCIBIOS_DEVICE_NOT_FOUND:
 136                 return XEN_PCI_ERR_dev_not_found;
 137         case PCIBIOS_BAD_REGISTER_NUMBER:
 138                 return XEN_PCI_ERR_invalid_offset;
 139         case PCIBIOS_FUNC_NOT_SUPPORTED:
 140                 return XEN_PCI_ERR_not_implemented;
 141         case PCIBIOS_SET_FAILED:
 142                 return XEN_PCI_ERR_access_denied;
 143         }
 144         return err;
 145 }
 146
 147 int xen_pcibk_config_read(struct pci_dev *dev, int offset, int size,
 148                           u32 *ret_val)
 149 {
 150         int err = 0;
 151         struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
 152         const struct config_field_entry *cfg_entry;
 153         const struct config_field *field;
 154         int field_start, field_end;
 155         /* if read fails for any reason, return 0
 156          * (as if device didn't respond) */
 157         u32 value = 0, tmp_val;
 158
 159         dev_dbg(&dev->dev, "read %d bytes at 0x%x\n", size, offset);
 160
 161         if (!valid_request(offset, size)) {
 162                 err = XEN_PCI_ERR_invalid_offset;
 163                 goto out;
 164         }
 165
 166         /* Get the real value first, then modify as appropriate */
 167         switch (size) {
 168         case 1:
 169                 err = pci_read_config_byte(dev, offset, (u8 *) &value);
 170                 break;
 171         case 2:
 172                 err = pci_read_config_word(dev, offset, (u16 *) &value);
 173                 break;
 174         case 4:
 175                 err = pci_read_config_dword(dev, offset, &value);
 176                 break;
 177         }
 178
 179         list_for_each_entry(cfg_entry, &dev_data->config_fields, list) {
 180                 field = cfg_entry->field;
 181
 182                 field_start = OFFSET(cfg_entry);
 183                 field_end = OFFSET(cfg_entry) + field->size;
 184
 185                 if (offset + size > field_start && field_end > offset) {
 186                         err = conf_space_read(dev, cfg_entry, field_start,
 187                                               &tmp_val);
 188                         if (err)
 189                                 goto out;
 190
 191                         value = merge_value(value, tmp_val,
 192                                             get_mask(field->size),
 193                                             field_start - offset);
 194                 }
 195         }
 196
 197 out:
 198         dev_dbg(&dev->dev, "read %d bytes at 0x%x = %x\n", size, offset, value);
 199
 200         *ret_val = value;
 201         return xen_pcibios_err_to_errno(err);
 202 }
 203
 204 int xen_pcibk_config_write(struct pci_dev *dev, int offset, int size, u32 value)
 205 {
 206         int err = 0, handled = 0;
 207         struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
 208         const struct config_field_entry *cfg_entry;
 209         const struct config_field *field;
 210         u32 tmp_val;
 211         int field_start, field_end;
 212
 213         dev_dbg(&dev->dev, "write request %d bytes at 0x%x = %x\n",
 214                 size, offset, value);
 215
 216         if (!valid_request(offset, size))
 217                 return XEN_PCI_ERR_invalid_offset;
 218
 219         list_for_each_entry(cfg_entry, &dev_data->config_fields, list) {
 220                 field = cfg_entry->field;
 221
 222                 field_start = OFFSET(cfg_entry);
 223                 field_end = OFFSET(cfg_entry) + field->size;
 224
 225                 if (offset + size > field_start && field_end > offset) {
 226                         err = conf_space_read(dev, cfg_entry, field_start,
 227                                               &tmp_val);
 228                         if (err)
 229                                 break;
 230
 231                         tmp_val = merge_value(tmp_val, value, get_mask(size),
 232                                               offset - field_start);
 233
 234                         err = conf_space_write(dev, cfg_entry, field_start,
 235                                                tmp_val);
 236
 237                         /* handled is set true here, but not every byte
 238                          * may have been written! Properly detecting if
 239                          * every byte is handled is unnecessary as the
 240                          * flag is used to detect devices that need
 241                          * special helpers to work correctly.
 242                          */
 243                         handled = 1;
 244                 }
 245         }
 246
 247         if (!handled && !err) {
 248                 /* By default, anything not specificially handled above is
 249                  * read-only. The permissive flag changes this behavior so
 250                  * that anything not specifically handled above is writable.
 251                  * This means that some fields may still be read-only because
 252                  * they have entries in the config_field list that intercept
 253                  * the write and do nothing. */
 254                 if (dev_data->permissive || xen_pcibk_permissive) {
 255                         switch (size) {
 256                         case 1:
 257                                 err = pci_write_config_byte(dev, offset,
 258                                                             (u8) value);
 259                                 break;
 260                         case 2:
 261                                 err = pci_write_config_word(dev, offset,
 262                                                             (u16) value);
 263                                 break;
 264                         case 4:
 265                                 err = pci_write_config_dword(dev, offset,
 266                                                              (u32) value);
 267                                 break;
 268                         }
 269                 } else if (!dev_data->warned_on_write) {
 270                         dev_data->warned_on_write = 1;
 271                         dev_warn(&dev->dev, "Driver tried to write to a "
 272                                  "read-only configuration space field at offset"
 273                                  " 0x%x, size %d. This may be harmless, but if "
 274                                  "you have problems with your device:\n"
 275                                  "1) see permissive attribute in sysfs\n"
 276                                  "2) report problems to the xen-devel "
 277                                  "mailing list along with details of your "
 278                                  "device obtained from lspci.\n", offset, size);
 279                 }
 280         }
 281
 282         return xen_pcibios_err_to_errno(err);
 283 }
 284
 285 int xen_pcibk_get_interrupt_type(struct pci_dev *dev)
 286 {
 287         int err;
 288         u16 val;
 289         int ret = 0;
 290
 291         /*
 292          * Do not trust dev->msi(x)_enabled here, as enabling could be done
 293          * bypassing the pci_*msi* functions, by the qemu.
 294          */
 295         if (dev->msi_cap) {
 296                 err = pci_read_config_word(dev,
 297                                 dev->msi_cap + PCI_MSI_FLAGS,
 298                                 &val);
 299                 if (err)
 300                         return err;
 301                 if (val & PCI_MSI_FLAGS_ENABLE)
 302                         ret |= INTERRUPT_TYPE_MSI;
 303         }
 304         if (dev->msix_cap) {
 305                 err = pci_read_config_word(dev,
 306                                 dev->msix_cap + PCI_MSIX_FLAGS,
 307                                 &val);
 308                 if (err)
 309                         return err;
 310                 if (val & PCI_MSIX_FLAGS_ENABLE)
 311                         ret |= INTERRUPT_TYPE_MSIX;
 312         }
 313
 314         /*
 315          * PCIe spec says device cannot use INTx if MSI/MSI-X is enabled,
 316          * so check for INTx only when both are disabled.
 317          */
 318         if (!ret) {
 319                 err = pci_read_config_word(dev, PCI_COMMAND, &val);
 320                 if (err)
 321                         return err;
 322                 if (!(val & PCI_COMMAND_INTX_DISABLE))
 323                         ret |= INTERRUPT_TYPE_INTX;
 324         }
 325
 326         return ret ?: INTERRUPT_TYPE_NONE;
 327 }
 328
 329 void xen_pcibk_config_free_dyn_fields(struct pci_dev *dev)
 330 {
 331         struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
 332         struct config_field_entry *cfg_entry, *t;
 333         const struct config_field *field;
 334
 335         dev_dbg(&dev->dev, "free-ing dynamically allocated virtual "
 336                            "configuration space fields\n");
 337         if (!dev_data)
 338                 return;
 339
 340         list_for_each_entry_safe(cfg_entry, t, &dev_data->config_fields, list) {
 341                 field = cfg_entry->field;
 342
 343                 if (field->clean) {
 344                         field->clean((struct config_field *)field);
 345
 346                         kfree(cfg_entry->data);
 347
 348                         list_del(&cfg_entry->list);
 349                         kfree(cfg_entry);
 350                 }
 351
 352         }
 353 }
 354
 355 void xen_pcibk_config_reset_dev(struct pci_dev *dev)
 356 {
 357         struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
 358         const struct config_field_entry *cfg_entry;
 359         const struct config_field *field;
 360
 361         dev_dbg(&dev->dev, "resetting virtual configuration space\n");
 362         if (!dev_data)
 363                 return;
 364
 365         list_for_each_entry(cfg_entry, &dev_data->config_fields, list) {
 366                 field = cfg_entry->field;
 367
 368                 if (field->reset)
 369                         field->reset(dev, OFFSET(cfg_entry), cfg_entry->data);
 370         }
 371 }
 372
 373 void xen_pcibk_config_free_dev(struct pci_dev *dev)
 374 {
 375         struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
 376         struct config_field_entry *cfg_entry, *t;
 377         const struct config_field *field;
 378
 379         dev_dbg(&dev->dev, "free-ing virtual configuration space fields\n");
 380         if (!dev_data)
 381                 return;
 382
 383         list_for_each_entry_safe(cfg_entry, t, &dev_data->config_fields, list) {
 384                 list_del(&cfg_entry->list);
 385
 386                 field = cfg_entry->field;
 387
 388                 if (field->release)
 389                         field->release(dev, OFFSET(cfg_entry), cfg_entry->data);
 390
 391                 kfree(cfg_entry);
 392         }
 393 }
 394
 395 int xen_pcibk_config_add_field_offset(struct pci_dev *dev,
 396                                     const struct config_field *field,
 397                                     unsigned int base_offset)
 398 {
 399         int err = 0;
 400         struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
 401         struct config_field_entry *cfg_entry;
 402         void *tmp;
 403
 404         cfg_entry = kmalloc(sizeof(*cfg_entry), GFP_KERNEL);
 405         if (!cfg_entry) {
 406                 err = -ENOMEM;
 407                 goto out;
 408         }
 409
 410         cfg_entry->data = NULL;
 411         cfg_entry->field = field;
 412         cfg_entry->base_offset = base_offset;
 413
 414         /* silently ignore duplicate fields */
 415         err = xen_pcibk_field_is_dup(dev, OFFSET(cfg_entry));
 416         if (err)
 417                 goto out;
 418
 419         if (field->init) {
 420                 tmp = field->init(dev, OFFSET(cfg_entry));
 421
 422                 if (IS_ERR(tmp)) {
 423                         err = PTR_ERR(tmp);
 424                         goto out;
 425                 }
 426
 427                 cfg_entry->data = tmp;
 428         }
 429
 430         dev_dbg(&dev->dev, "added config field at offset 0x%02x\n",
 431                 OFFSET(cfg_entry));
 432         list_add_tail(&cfg_entry->list, &dev_data->config_fields);
 433
 434 out:
 435         if (err)
 436                 kfree(cfg_entry);
 437
 438         return err;
 439 }
 440
 441 /* This sets up the device's virtual configuration space to keep track of
 442  * certain registers (like the base address registers (BARs) so that we can
 443  * keep the client from manipulating them directly.
 444  */
 445 int xen_pcibk_config_init_dev(struct pci_dev *dev)
 446 {
 447         int err = 0;
 448         struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
 449
 450         dev_dbg(&dev->dev, "initializing virtual configuration space\n");
 451
 452         INIT_LIST_HEAD(&dev_data->config_fields);
 453
 454         err = xen_pcibk_config_header_add_fields(dev);
 455         if (err)
 456                 goto out;
 457
 458         err = xen_pcibk_config_capability_add_fields(dev);
 459         if (err)
 460                 goto out;
 461
 462         err = xen_pcibk_config_quirks_init(dev);
 463
 464 out:
 465         return err;
 466 }
 467
 468 int xen_pcibk_config_init(void)
 469 {
 470         return xen_pcibk_config_capability_init();
 471 }