OvmfPkg/VirtioBlkDxe/VirtioBlk.c

   1 /** @file
   2
   3   This driver produces Block I/O Protocol instances for virtio-blk devices.
   4
   5   The implementation is basic:
   6
   7   - No attach/detach (ie. removable media).
   8
   9   - Although the non-blocking interfaces of EFI_BLOCK_IO2_PROTOCOL could be a
  10     good match for multiple in-flight virtio-blk requests, we stick to
  11     synchronous requests and EFI_BLOCK_IO_PROTOCOL for now.
  12
  13   Copyright (C) 2012, Red Hat, Inc.
  14   Copyright (c) 2012, Intel Corporation. All rights reserved.<BR>
  15
  16   This program and the accompanying materials are licensed and made available
  17   under the terms and conditions of the BSD License which accompanies this
  18   distribution. The full text of the license may be found at
  19   http://opensource.org/licenses/bsd-license.php
  20
  21   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
  22   WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  23
  24 **/
  25
  26 #include <IndustryStandard/VirtioBlk.h>
  27 #include <Library/BaseMemoryLib.h>
  28 #include <Library/DebugLib.h>
  29 #include <Library/MemoryAllocationLib.h>
  30 #include <Library/UefiBootServicesTableLib.h>
  31 #include <Library/UefiLib.h>
  32 #include <Library/VirtioLib.h>
  33
  34 #include "VirtioBlk.h"
  35
  36 /**
  37
  38   Convenience macros to read and write region 0 IO space elements of the
  39   virtio-blk device, for configuration purposes.
  40
  41   The following macros make it possible to specify only the "core parameters"
  42   for such accesses and to derive the rest. By the time VIRTIO_CFG_WRITE()
  43   returns, the transaction will have been completed.
  44
  45   @param[in] Dev       Pointer to the VBLK_DEV structure whose VirtIo space
  46                        we're accessing. Dev->VirtIo must be valid.
  47
  48   @param[in] Field     A field name from VBLK_HDR, identifying the virtio-blk
  49                        configuration item to access.
  50
  51   @param[in] Value     (VIRTIO_CFG_WRITE() only.) The value to write to the
  52                        selected configuration item.
  53
  54   @param[out] Pointer  (VIRTIO_CFG_READ() only.) The object to receive the
  55                        value read from the configuration item. Its type must be
  56                        one of UINT8, UINT16, UINT32, UINT64.
  57
  58
  59   @return  Status code returned by Virtio->WriteDevice() /
  60            Virtio->ReadDevice().
  61
  62 **/
  63
  64 #define VIRTIO_CFG_WRITE(Dev, Field, Value)  ((Dev)->VirtIo->WriteDevice ( \
  65                                                 (Dev)->VirtIo,             \
  66                                                 OFFSET_OF_VBLK (Field),    \
  67                                                 SIZE_OF_VBLK (Field),      \
  68                                                 (Value)                    \
  69                                                 ))
  70
  71 #define VIRTIO_CFG_READ(Dev, Field, Pointer) ((Dev)->VirtIo->ReadDevice (  \
  72                                                 (Dev)->VirtIo,             \
  73                                                 OFFSET_OF_VBLK (Field),    \
  74                                                 SIZE_OF_VBLK (Field),      \
  75                                                 sizeof *(Pointer),         \
  76                                                 (Pointer)                  \
  77                                                 ))
  78
  79
  80 //
  81 // UEFI Spec 2.3.1 + Errata C, 12.8 EFI Block I/O Protocol
  82 // Driver Writer's Guide for UEFI 2.3.1 v1.01,
  83 //   24.2 Block I/O Protocol Implementations
  84 //
  85 EFI_STATUS
  86 EFIAPI
  87 VirtioBlkReset (
  88   IN EFI_BLOCK_IO_PROTOCOL *This,
  89   IN BOOLEAN               ExtendedVerification
  90   )
  91 {
  92   //
  93   // If we managed to initialize and install the driver, then the device is
  94   // working correctly.
  95   //
  96   return EFI_SUCCESS;
  97 }
  98
  99 /**
 100
 101   Verify correctness of the read/write (not flush) request submitted to the
 102   EFI_BLOCK_IO_PROTOCOL instance.
 103
 104   This function provides most verification steps described in:
 105
 106     UEFI Spec 2.3.1 + Errata C, 12.8 EFI Block I/O Protocol, 12.8 EFI Block I/O
 107     Protocol,
 108     - EFI_BLOCK_IO_PROTOCOL.ReadBlocks()
 109     - EFI_BLOCK_IO_PROTOCOL.WriteBlocks()
 110
 111     Driver Writer's Guide for UEFI 2.3.1 v1.01,
 112     - 24.2.2. ReadBlocks() and ReadBlocksEx() Implementation
 113     - 24.2.3 WriteBlocks() and WriteBlockEx() Implementation
 114
 115   Request sizes are limited to 1 GB (checked). This is not a practical
 116   limitation, just conformance to virtio-0.9.5, 2.3.2 Descriptor Table: "no
 117   descriptor chain may be more than 2^32 bytes long in total".
 118
 119   Some Media characteristics are hardcoded in VirtioBlkInit() below (like
 120   non-removable media, no restriction on buffer alignment etc); we rely on
 121   those here without explicit mention.
 122
 123   @param[in] Media               The EFI_BLOCK_IO_MEDIA characteristics for
 124                                  this driver instance, extracted from the
 125                                  underlying virtio-blk device at initialization
 126                                  time. We validate the request against this set
 127                                  of attributes.
 128
 129
 130   @param[in] Lba                 Logical Block Address: number of logical
 131                                  blocks to skip from the beginning of the
 132                                  device.
 133
 134   @param[in] PositiveBufferSize  Size of buffer to transfer, in bytes. The
 135                                  caller is responsible to ensure this parameter
 136                                  is positive.
 137
 138   @param[in] RequestIsWrite      TRUE iff data transfer goes from guest to
 139                                  device.
 140
 141
 142   @@return                       Validation result to be forwarded outwards by
 143                                  ReadBlocks() and WriteBlocks, as required by
 144                                  the specs above.
 145
 146 **/
 147 STATIC
 148 EFI_STATUS
 149 EFIAPI
 150 VerifyReadWriteRequest (
 151   IN  EFI_BLOCK_IO_MEDIA *Media,
 152   IN  EFI_LBA            Lba,
 153   IN  UINTN              PositiveBufferSize,
 154   IN  BOOLEAN            RequestIsWrite
 155   )
 156 {
 157   UINTN BlockCount;
 158
 159   ASSERT (PositiveBufferSize > 0);
 160
 161   if (PositiveBufferSize > SIZE_1GB ||
 162       PositiveBufferSize % Media->BlockSize > 0) {
 163     return EFI_BAD_BUFFER_SIZE;
 164   }
 165   BlockCount = PositiveBufferSize / Media->BlockSize;
 166
 167   //
 168   // Avoid unsigned wraparound on either side in the second comparison.
 169   //
 170   if (Lba > Media->LastBlock || BlockCount - 1 > Media->LastBlock - Lba) {
 171     return EFI_INVALID_PARAMETER;
 172   }
 173
 174   if (RequestIsWrite && Media->ReadOnly) {
 175     return EFI_WRITE_PROTECTED;
 176   }
 177
 178   return EFI_SUCCESS;
 179 }
 180
 181
 182
 183
 184 /**
 185
 186   Format a read / write / flush request as three consecutive virtio
 187   descriptors, push them to the host, and poll for the response.
 188
 189   This is the main workhorse function. Two use cases are supported, read/write
 190   and flush. The function may only be called after the request parameters have
 191   been verified by
 192   - specific checks in ReadBlocks() / WriteBlocks() / FlushBlocks(), and
 193   - VerifyReadWriteRequest() (for read/write only).
 194
 195   Parameters handled commonly:
 196
 197     @param[in] Dev             The virtio-blk device the request is targeted
 198                                at.
 199
 200   Flush request:
 201
 202     @param[in] Lba             Must be zero.
 203
 204     @param[in] BufferSize      Must be zero.
 205
 206     @param[in out] Buffer      Ignored by the function.
 207
 208     @param[in] RequestIsWrite  Must be TRUE.
 209
 210   Read/Write request:
 211
 212     @param[in] Lba             Logical Block Address: number of logical blocks
 213                                to skip from the beginning of the device.
 214
 215     @param[in] BufferSize      Size of buffer to transfer, in bytes. The caller
 216                                is responsible to ensure this parameter is
 217                                positive.
 218
 219     @param[in out] Buffer      The guest side area to read data from the device
 220                                into, or write data to the device from.
 221
 222     @param[in] RequestIsWrite  TRUE iff data transfer goes from guest to
 223                                device.
 224
 225   Return values are common to both use cases, and are appropriate to be
 226   forwarded by the EFI_BLOCK_IO_PROTOCOL functions (ReadBlocks(),
 227   WriteBlocks(), FlushBlocks()).
 228
 229
 230   @retval EFI_SUCCESS          Transfer complete.
 231
 232   @retval EFI_DEVICE_ERROR     Failed to notify host side via VirtIo write, or
 233                                unable to parse host response, or host response
 234                                is not VIRTIO_BLK_S_OK.
 235
 236 **/
 237
 238 STATIC
 239 EFI_STATUS
 240 EFIAPI
 241 SynchronousRequest (
 242   IN              VBLK_DEV *Dev,
 243   IN              EFI_LBA  Lba,
 244   IN              UINTN    BufferSize,
 245   IN OUT volatile VOID     *Buffer,
 246   IN              BOOLEAN  RequestIsWrite
 247   )
 248 {
 249   UINT32                  BlockSize;
 250   volatile VIRTIO_BLK_REQ Request;
 251   volatile UINT8          HostStatus;
 252   DESC_INDICES            Indices;
 253
 254   BlockSize = Dev->BlockIoMedia.BlockSize;
 255
 256   //
 257   // ensured by VirtioBlkInit()
 258   //
 259   ASSERT (BlockSize > 0);
 260   ASSERT (BlockSize % 512 == 0);
 261
 262   //
 263   // ensured by contract above, plus VerifyReadWriteRequest()
 264   //
 265   ASSERT (BufferSize % BlockSize == 0);
 266
 267   //
 268   // Prepare virtio-blk request header, setting zero size for flush.
 269   // IO Priority is homogeneously 0.
 270   //
 271   Request.Type   = RequestIsWrite ?
 272                    (BufferSize == 0 ? VIRTIO_BLK_T_FLUSH : VIRTIO_BLK_T_OUT) :
 273                    VIRTIO_BLK_T_IN;
 274   Request.IoPrio = 0;
 275   Request.Sector = MultU64x32(Lba, BlockSize / 512);
 276
 277   VirtioPrepare (&Dev->Ring, &Indices);
 278
 279   //
 280   // preset a host status for ourselves that we do not accept as success
 281   //
 282   HostStatus = VIRTIO_BLK_S_IOERR;
 283
 284   //
 285   // ensured by VirtioBlkInit() -- this predicate, in combination with the
 286   // lock-step progress, ensures we don't have to track free descriptors.
 287   //
 288   ASSERT (Dev->Ring.QueueSize >= 3);
 289
 290   //
 291   // virtio-blk header in first desc
 292   //
 293   VirtioAppendDesc (&Dev->Ring, (UINTN) &Request, sizeof Request,
 294     VRING_DESC_F_NEXT, &Indices);
 295
 296   //
 297   // data buffer for read/write in second desc
 298   //
 299   if (BufferSize > 0) {
 300     //
 301     // From virtio-0.9.5, 2.3.2 Descriptor Table:
 302     // "no descriptor chain may be more than 2^32 bytes long in total".
 303     //
 304     // The predicate is ensured by the call contract above (for flush), or
 305     // VerifyReadWriteRequest() (for read/write). It also implies that
 306     // converting BufferSize to UINT32 will not truncate it.
 307     //
 308     ASSERT (BufferSize <= SIZE_1GB);
 309
 310     //
 311     // VRING_DESC_F_WRITE is interpreted from the host's point of view.
 312     //
 313     VirtioAppendDesc (&Dev->Ring, (UINTN) Buffer, (UINT32) BufferSize,
 314       VRING_DESC_F_NEXT | (RequestIsWrite ? 0 : VRING_DESC_F_WRITE),
 315       &Indices);
 316   }
 317
 318   //
 319   // host status in last (second or third) desc
 320   //
 321   VirtioAppendDesc (&Dev->Ring, (UINTN) &HostStatus, sizeof HostStatus,
 322     VRING_DESC_F_WRITE, &Indices);
 323
 324   //
 325   // virtio-blk's only virtqueue is #0, called "requestq" (see Appendix D).
 326   //
 327   if (VirtioFlush (Dev->VirtIo, 0, &Dev->Ring, &Indices) == EFI_SUCCESS &&
 328       HostStatus == VIRTIO_BLK_S_OK) {
 329     return EFI_SUCCESS;
 330   }
 331
 332   return EFI_DEVICE_ERROR;
 333 }
 334
 335
 336 /**
 337
 338   ReadBlocks() operation for virtio-blk.
 339
 340   See
 341   - UEFI Spec 2.3.1 + Errata C, 12.8 EFI Block I/O Protocol, 12.8 EFI Block I/O
 342     Protocol, EFI_BLOCK_IO_PROTOCOL.ReadBlocks().
 343   - Driver Writer's Guide for UEFI 2.3.1 v1.01, 24.2.2. ReadBlocks() and
 344     ReadBlocksEx() Implementation.
 345
 346   Parameter checks and conformant return values are implemented in
 347   VerifyReadWriteRequest() and SynchronousRequest().
 348
 349   A zero BufferSize doesn't seem to be prohibited, so do nothing in that case,
 350   successfully.
 351
 352 **/
 353
 354 EFI_STATUS
 355 EFIAPI
 356 VirtioBlkReadBlocks (
 357   IN  EFI_BLOCK_IO_PROTOCOL *This,
 358   IN  UINT32                MediaId,
 359   IN  EFI_LBA               Lba,
 360   IN  UINTN                 BufferSize,
 361   OUT VOID                  *Buffer
 362   )
 363 {
 364   VBLK_DEV   *Dev;
 365   EFI_STATUS Status;
 366
 367   if (BufferSize == 0) {
 368     return EFI_SUCCESS;
 369   }
 370
 371   Dev = VIRTIO_BLK_FROM_BLOCK_IO (This);
 372   Status = VerifyReadWriteRequest (
 373              &Dev->BlockIoMedia,
 374              Lba,
 375              BufferSize,
 376              FALSE               // RequestIsWrite
 377              );
 378   if (EFI_ERROR (Status)) {
 379     return Status;
 380   }
 381
 382   return SynchronousRequest (
 383            Dev,
 384            Lba,
 385            BufferSize,
 386            Buffer,
 387            FALSE       // RequestIsWrite
 388            );
 389 }
 390
 391 /**
 392
 393   WriteBlocks() operation for virtio-blk.
 394
 395   See
 396   - UEFI Spec 2.3.1 + Errata C, 12.8 EFI Block I/O Protocol, 12.8 EFI Block I/O
 397     Protocol, EFI_BLOCK_IO_PROTOCOL.WriteBlocks().
 398   - Driver Writer's Guide for UEFI 2.3.1 v1.01, 24.2.3 WriteBlocks() and
 399     WriteBlockEx() Implementation.
 400
 401   Parameter checks and conformant return values are implemented in
 402   VerifyReadWriteRequest() and SynchronousRequest().
 403
 404   A zero BufferSize doesn't seem to be prohibited, so do nothing in that case,
 405   successfully.
 406
 407 **/
 408
 409 EFI_STATUS
 410 EFIAPI
 411 VirtioBlkWriteBlocks (
 412   IN EFI_BLOCK_IO_PROTOCOL *This,
 413   IN UINT32                MediaId,
 414   IN EFI_LBA               Lba,
 415   IN UINTN                 BufferSize,
 416   IN VOID                  *Buffer
 417   )
 418 {
 419   VBLK_DEV   *Dev;
 420   EFI_STATUS Status;
 421
 422   if (BufferSize == 0) {
 423     return EFI_SUCCESS;
 424   }
 425
 426   Dev = VIRTIO_BLK_FROM_BLOCK_IO (This);
 427   Status = VerifyReadWriteRequest (
 428              &Dev->BlockIoMedia,
 429              Lba,
 430              BufferSize,
 431              TRUE                // RequestIsWrite
 432              );
 433   if (EFI_ERROR (Status)) {
 434     return Status;
 435   }
 436
 437   return SynchronousRequest (
 438            Dev,
 439            Lba,
 440            BufferSize,
 441            Buffer,
 442            TRUE        // RequestIsWrite
 443            );
 444 }
 445
 446
 447 /**
 448
 449   FlushBlocks() operation for virtio-blk.
 450
 451   See
 452   - UEFI Spec 2.3.1 + Errata C, 12.8 EFI Block I/O Protocol, 12.8 EFI Block I/O
 453     Protocol, EFI_BLOCK_IO_PROTOCOL.FlushBlocks().
 454   - Driver Writer's Guide for UEFI 2.3.1 v1.01, 24.2.4 FlushBlocks() and
 455     FlushBlocksEx() Implementation.
 456
 457   If the underlying virtio-blk device doesn't support flushing (ie.
 458   write-caching), then this function should not be called by higher layers,
 459   according to EFI_BLOCK_IO_MEDIA characteristics set in VirtioBlkInit().
 460   Should they do nonetheless, we do nothing, successfully.
 461
 462 **/
 463
 464 EFI_STATUS
 465 EFIAPI
 466 VirtioBlkFlushBlocks (
 467   IN EFI_BLOCK_IO_PROTOCOL *This
 468   )
 469 {
 470   VBLK_DEV *Dev;
 471
 472   Dev = VIRTIO_BLK_FROM_BLOCK_IO (This);
 473   return Dev->BlockIoMedia.WriteCaching ?
 474            SynchronousRequest (
 475              Dev,
 476              0,    // Lba
 477              0,    // BufferSize
 478              NULL, // Buffer
 479              TRUE  // RequestIsWrite
 480              ) :
 481            EFI_SUCCESS;
 482 }
 483
 484
 485 /**
 486
 487   Device probe function for this driver.
 488
 489   The DXE core calls this function for any given device in order to see if the
 490   driver can drive the device.
 491
 492   Specs relevant in the general sense:
 493
 494   - UEFI Spec 2.3.1 + Errata C:
 495     - 6.3 Protocol Handler Services -- for accessing the underlying device
 496     - 10.1 EFI Driver Binding Protocol -- for exporting ourselves
 497
 498   - Driver Writer's Guide for UEFI 2.3.1 v1.01:
 499     - 5.1.3.4 OpenProtocol() and CloseProtocol() -- for accessing the
 500       underlying device
 501     - 9 Driver Binding Protocol -- for exporting ourselves
 502
 503   @param[in]  This                The EFI_DRIVER_BINDING_PROTOCOL object
 504                                   incorporating this driver (independently of
 505                                   any device).
 506
 507   @param[in] DeviceHandle         The device to probe.
 508
 509   @param[in] RemainingDevicePath  Relevant only for bus drivers, ignored.
 510
 511
 512   @retval EFI_SUCCESS      The driver supports the device being probed.
 513
 514   @retval EFI_UNSUPPORTED  Based on virtio-blk discovery, we do not support
 515                            the device.
 516
 517   @return                  Error codes from the OpenProtocol() boot service or
 518                            the VirtIo protocol.
 519
 520 **/
 521
 522 EFI_STATUS
 523 EFIAPI
 524 VirtioBlkDriverBindingSupported (
 525   IN EFI_DRIVER_BINDING_PROTOCOL *This,
 526   IN EFI_HANDLE                  DeviceHandle,
 527   IN EFI_DEVICE_PATH_PROTOCOL    *RemainingDevicePath
 528   )
 529 {
 530   EFI_STATUS          Status;
 531   VIRTIO_DEVICE_PROTOCOL *VirtIo;
 532
 533   //
 534   // Attempt to open the device with the VirtIo set of interfaces. On success,
 535   // the protocol is "instantiated" for the VirtIo device. Covers duplicate
 536   // open attempts (EFI_ALREADY_STARTED).
 537   //
 538   Status = gBS->OpenProtocol (
 539                   DeviceHandle,               // candidate device
 540                   &gVirtioDeviceProtocolGuid, // for generic VirtIo access
 541                   (VOID **)&VirtIo,           // handle to instantiate
 542                   This->DriverBindingHandle,  // requestor driver identity
 543                   DeviceHandle,               // ControllerHandle, according to
 544                                               // the UEFI Driver Model
 545                   EFI_OPEN_PROTOCOL_BY_DRIVER // get exclusive VirtIo access to
 546                                               // the device; to be released
 547                   );
 548   if (EFI_ERROR (Status)) {
 549     return Status;
 550   }
 551
 552   if (VirtIo->SubSystemDeviceId != VIRTIO_SUBSYSTEM_BLOCK_DEVICE) {
 553     Status = EFI_UNSUPPORTED;
 554   }
 555
 556   //
 557   // We needed VirtIo access only transitorily, to see whether we support the
 558   // device or not.
 559   //
 560   gBS->CloseProtocol (DeviceHandle, &gVirtioDeviceProtocolGuid,
 561          This->DriverBindingHandle, DeviceHandle);
 562   return Status;
 563 }
 564
 565
 566 /**
 567
 568   Set up all BlockIo and virtio-blk aspects of this driver for the specified
 569   device.
 570
 571   @param[in out] Dev  The driver instance to configure. The caller is
 572                       responsible for Dev->VirtIo's validity (ie. working IO
 573                       access to the underlying virtio-blk device).
 574
 575   @retval EFI_SUCCESS      Setup complete.
 576
 577   @retval EFI_UNSUPPORTED  The driver is unable to work with the virtio ring or
 578                            virtio-blk attributes the host provides.
 579
 580   @return                  Error codes from VirtioRingInit() or
 581                            VIRTIO_CFG_READ() / VIRTIO_CFG_WRITE().
 582
 583 **/
 584
 585 STATIC
 586 EFI_STATUS
 587 EFIAPI
 588 VirtioBlkInit (
 589   IN OUT VBLK_DEV *Dev
 590   )
 591 {
 592   UINT8      NextDevStat;
 593   EFI_STATUS Status;
 594
 595   UINT32     Features;
 596   UINT64     NumSectors;
 597   UINT32     BlockSize;
 598   UINT16     QueueSize;
 599
 600   //
 601   // Execute virtio-0.9.5, 2.2.1 Device Initialization Sequence.
 602   //
 603   NextDevStat = 0;             // step 1 -- reset device
 604   Status = Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, NextDevStat);
 605   if (EFI_ERROR (Status)) {
 606     goto Failed;
 607   }
 608
 609   NextDevStat |= VSTAT_ACK;    // step 2 -- acknowledge device presence
 610   Status = Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, NextDevStat);
 611   if (EFI_ERROR (Status)) {
 612     goto Failed;
 613   }
 614
 615   NextDevStat |= VSTAT_DRIVER; // step 3 -- we know how to drive it
 616   Status = Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, NextDevStat);
 617   if (EFI_ERROR (Status)) {
 618     goto Failed;
 619   }
 620
 621   //
 622   // Set Page Size - MMIO VirtIo Specific
 623   //
 624   Status = Dev->VirtIo->SetPageSize (Dev->VirtIo, EFI_PAGE_SIZE);
 625   if (EFI_ERROR (Status)) {
 626     goto Failed;
 627   }
 628
 629   //
 630   // step 4a -- retrieve and validate features
 631   //
 632   Status = Dev->VirtIo->GetDeviceFeatures (Dev->VirtIo, &Features);
 633   if (EFI_ERROR (Status)) {
 634     goto Failed;
 635   }
 636
 637   Status = VIRTIO_CFG_READ (Dev, Capacity, &NumSectors);
 638   if (EFI_ERROR (Status)) {
 639     goto Failed;
 640   }
 641   if (NumSectors == 0) {
 642     Status = EFI_UNSUPPORTED;
 643     goto Failed;
 644   }
 645
 646   if (Features & VIRTIO_BLK_F_BLK_SIZE) {
 647     Status = VIRTIO_CFG_READ (Dev, BlkSize, &BlockSize);
 648     if (EFI_ERROR (Status)) {
 649       goto Failed;
 650     }
 651     if (BlockSize == 0 || BlockSize % 512 != 0 ||
 652         ModU64x32 (NumSectors, BlockSize / 512) != 0) {
 653       //
 654       // We can only handle a logical block consisting of whole sectors,
 655       // and only a disk composed of whole logical blocks.
 656       //
 657       Status = EFI_UNSUPPORTED;
 658       goto Failed;
 659     }
 660   }
 661   else {
 662     BlockSize = 512;
 663   }
 664
 665   //
 666   // step 4b -- allocate virtqueue
 667   //
 668   Status = Dev->VirtIo->SetQueueSel (Dev->VirtIo, 0);
 669   if (EFI_ERROR (Status)) {
 670     goto Failed;
 671   }
 672   Status = Dev->VirtIo->GetQueueNumMax (Dev->VirtIo, &QueueSize);
 673   if (EFI_ERROR (Status)) {
 674     goto Failed;
 675   }
 676   if (QueueSize < 3) { // SynchronousRequest() uses at most three descriptors
 677     Status = EFI_UNSUPPORTED;
 678     goto Failed;
 679   }
 680
 681   Status = VirtioRingInit (QueueSize, &Dev->Ring);
 682   if (EFI_ERROR (Status)) {
 683     goto Failed;
 684   }
 685
 686   //
 687   // Additional steps for MMIO: align the queue appropriately, and set the
 688   // size. If anything fails from here on, we must release the ring resources.
 689   //
 690   Status = Dev->VirtIo->SetQueueNum (Dev->VirtIo, QueueSize);
 691   if (EFI_ERROR (Status)) {
 692     goto ReleaseQueue;
 693   }
 694
 695   Status = Dev->VirtIo->SetQueueAlign (Dev->VirtIo, EFI_PAGE_SIZE);
 696   if (EFI_ERROR (Status)) {
 697     goto ReleaseQueue;
 698   }
 699
 700   //
 701   // step 4c -- Report GPFN (guest-physical frame number) of queue.
 702   //
 703   Status = Dev->VirtIo->SetQueueAddress (Dev->VirtIo,
 704       (UINT32) ((UINTN) Dev->Ring.Base >> EFI_PAGE_SHIFT));
 705   if (EFI_ERROR (Status)) {
 706     goto ReleaseQueue;
 707   }
 708
 709
 710   //
 711   // step 5 -- Report understood features. There are no virtio-blk specific
 712   // features to negotiate in virtio-0.9.5, plus we do not want any of the
 713   // device-independent (known or unknown) VIRTIO_F_* capabilities (see
 714   // Appendix B).
 715   //
 716   Status = Dev->VirtIo->SetGuestFeatures (Dev->VirtIo, 0);
 717   if (EFI_ERROR (Status)) {
 718     goto ReleaseQueue;
 719   }
 720
 721   //
 722   // step 6 -- initialization complete
 723   //
 724   NextDevStat |= VSTAT_DRIVER_OK;
 725   Status = Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, NextDevStat);
 726   if (EFI_ERROR (Status)) {
 727     goto ReleaseQueue;
 728   }
 729
 730   //
 731   // Populate the exported interface's attributes; see UEFI spec v2.3.1 +
 732   // Errata C, 12.8 EFI Block I/O Protocol. We stick to the lowest possible
 733   // EFI_BLOCK_IO_PROTOCOL revision for now.
 734   //
 735   Dev->BlockIo.Revision              = 0;
 736   Dev->BlockIo.Media                 = &Dev->BlockIoMedia;
 737   Dev->BlockIo.Reset                 = &VirtioBlkReset;
 738   Dev->BlockIo.ReadBlocks            = &VirtioBlkReadBlocks;
 739   Dev->BlockIo.WriteBlocks           = &VirtioBlkWriteBlocks;
 740   Dev->BlockIo.FlushBlocks           = &VirtioBlkFlushBlocks;
 741   Dev->BlockIoMedia.MediaId          = 0;
 742   Dev->BlockIoMedia.RemovableMedia   = FALSE;
 743   Dev->BlockIoMedia.MediaPresent     = TRUE;
 744   Dev->BlockIoMedia.LogicalPartition = FALSE;
 745   Dev->BlockIoMedia.ReadOnly         = !!(Features & VIRTIO_BLK_F_RO);
 746   Dev->BlockIoMedia.WriteCaching     = !!(Features & VIRTIO_BLK_F_FLUSH);
 747   Dev->BlockIoMedia.BlockSize        = BlockSize;
 748   Dev->BlockIoMedia.IoAlign          = 0;
 749   Dev->BlockIoMedia.LastBlock        = DivU64x32 (NumSectors,
 750                                          BlockSize / 512) - 1;
 751   return EFI_SUCCESS;
 752
 753 ReleaseQueue:
 754   VirtioRingUninit (&Dev->Ring);
 755
 756 Failed:
 757   //
 758   // Notify the host about our failure to setup: virtio-0.9.5, 2.2.2.1 Device
 759   // Status. VirtIo access failure here should not mask the original error.
 760   //
 761   NextDevStat |= VSTAT_FAILED;
 762   Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, NextDevStat);
 763
 764   return Status; // reached only via Failed above
 765 }
 766
 767
 768 /**
 769
 770   Uninitialize the internals of a virtio-blk device that has been successfully
 771   set up with VirtioBlkInit().
 772
 773   @param[in out]  Dev  The device to clean up.
 774
 775 **/
 776
 777 STATIC
 778 VOID
 779 EFIAPI
 780 VirtioBlkUninit (
 781   IN OUT VBLK_DEV *Dev
 782   )
 783 {
 784   //
 785   // Reset the virtual device -- see virtio-0.9.5, 2.2.2.1 Device Status. When
 786   // VIRTIO_CFG_WRITE() returns, the host will have learned to stay away from
 787   // the old comms area.
 788   //
 789   Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, 0);
 790
 791   VirtioRingUninit (&Dev->Ring);
 792
 793   SetMem (&Dev->BlockIo,      sizeof Dev->BlockIo,      0x00);
 794   SetMem (&Dev->BlockIoMedia, sizeof Dev->BlockIoMedia, 0x00);
 795 }
 796
 797
 798 /**
 799
 800   After we've pronounced support for a specific device in
 801   DriverBindingSupported(), we start managing said device (passed in by the
 802   Driver Exeuction Environment) with the following service.
 803
 804   See DriverBindingSupported() for specification references.
 805
 806   @param[in]  This                The EFI_DRIVER_BINDING_PROTOCOL object
 807                                   incorporating this driver (independently of
 808                                   any device).
 809
 810   @param[in] DeviceHandle         The supported device to drive.
 811
 812   @param[in] RemainingDevicePath  Relevant only for bus drivers, ignored.
 813
 814
 815   @retval EFI_SUCCESS           Driver instance has been created and
 816                                 initialized  for the virtio-blk device, it
 817                                 is now accessibla via EFI_BLOCK_IO_PROTOCOL.
 818
 819   @retval EFI_OUT_OF_RESOURCES  Memory allocation failed.
 820
 821   @return                       Error codes from the OpenProtocol() boot
 822                                 service, the VirtIo protocol, VirtioBlkInit(),
 823                                 or the InstallProtocolInterface() boot service.
 824
 825 **/
 826
 827 EFI_STATUS
 828 EFIAPI
 829 VirtioBlkDriverBindingStart (
 830   IN EFI_DRIVER_BINDING_PROTOCOL *This,
 831   IN EFI_HANDLE                  DeviceHandle,
 832   IN EFI_DEVICE_PATH_PROTOCOL    *RemainingDevicePath
 833   )
 834 {
 835   VBLK_DEV   *Dev;
 836   EFI_STATUS Status;
 837
 838   Dev = (VBLK_DEV *) AllocateZeroPool (sizeof *Dev);
 839   if (Dev == NULL) {
 840     return EFI_OUT_OF_RESOURCES;
 841   }
 842
 843   Status = gBS->OpenProtocol (DeviceHandle, &gVirtioDeviceProtocolGuid,
 844                   (VOID **)&Dev->VirtIo, This->DriverBindingHandle,
 845                   DeviceHandle, EFI_OPEN_PROTOCOL_BY_DRIVER);
 846   if (EFI_ERROR (Status)) {
 847     goto FreeVirtioBlk;
 848   }
 849
 850   //
 851   // VirtIo access granted, configure virtio-blk device.
 852   //
 853   Status = VirtioBlkInit (Dev);
 854   if (EFI_ERROR (Status)) {
 855     goto CloseVirtIo;
 856   }
 857
 858   //
 859   // Setup complete, attempt to export the driver instance's BlockIo interface.
 860   //
 861   Dev->Signature = VBLK_SIG;
 862   Status = gBS->InstallProtocolInterface (&DeviceHandle,
 863                   &gEfiBlockIoProtocolGuid, EFI_NATIVE_INTERFACE,
 864                   &Dev->BlockIo);
 865   if (EFI_ERROR (Status)) {
 866     goto UninitDev;
 867   }
 868
 869   return EFI_SUCCESS;
 870
 871 UninitDev:
 872   VirtioBlkUninit (Dev);
 873
 874 CloseVirtIo:
 875   gBS->CloseProtocol (DeviceHandle, &gVirtioDeviceProtocolGuid,
 876          This->DriverBindingHandle, DeviceHandle);
 877
 878 FreeVirtioBlk:
 879   FreePool (Dev);
 880
 881   return Status;
 882 }
 883
 884
 885 /**
 886
 887   Stop driving a virtio-blk device and remove its BlockIo interface.
 888
 889   This function replays the success path of DriverBindingStart() in reverse.
 890   The host side virtio-blk device is reset, so that the OS boot loader or the
 891   OS may reinitialize it.
 892
 893   @param[in] This               The EFI_DRIVER_BINDING_PROTOCOL object
 894                                 incorporating this driver (independently of any
 895                                 device).
 896
 897   @param[in] DeviceHandle       Stop driving this device.
 898
 899   @param[in] NumberOfChildren   Since this function belongs to a device driver
 900                                 only (as opposed to a bus driver), the caller
 901                                 environment sets NumberOfChildren to zero, and
 902                                 we ignore it.
 903
 904   @param[in] ChildHandleBuffer  Ignored (corresponding to NumberOfChildren).
 905
 906 **/
 907
 908 EFI_STATUS
 909 EFIAPI
 910 VirtioBlkDriverBindingStop (
 911   IN EFI_DRIVER_BINDING_PROTOCOL *This,
 912   IN EFI_HANDLE                  DeviceHandle,
 913   IN UINTN                       NumberOfChildren,
 914   IN EFI_HANDLE                  *ChildHandleBuffer
 915   )
 916 {
 917   EFI_STATUS            Status;
 918   EFI_BLOCK_IO_PROTOCOL *BlockIo;
 919   VBLK_DEV              *Dev;
 920
 921   Status = gBS->OpenProtocol (
 922                   DeviceHandle,                  // candidate device
 923                   &gEfiBlockIoProtocolGuid,      // retrieve the BlockIo iface
 924                   (VOID **)&BlockIo,             // target pointer
 925                   This->DriverBindingHandle,     // requestor driver identity
 926                   DeviceHandle,                  // requesting lookup for dev.
 927                   EFI_OPEN_PROTOCOL_GET_PROTOCOL // lookup only, no ref. added
 928                   );
 929   if (EFI_ERROR (Status)) {
 930     return Status;
 931   }
 932
 933   Dev = VIRTIO_BLK_FROM_BLOCK_IO (BlockIo);
 934
 935   //
 936   // Handle Stop() requests for in-use driver instances gracefully.
 937   //
 938   Status = gBS->UninstallProtocolInterface (DeviceHandle,
 939                   &gEfiBlockIoProtocolGuid, &Dev->BlockIo);
 940   if (EFI_ERROR (Status)) {
 941     return Status;
 942   }
 943
 944   VirtioBlkUninit (Dev);
 945
 946   gBS->CloseProtocol (DeviceHandle, &gVirtioDeviceProtocolGuid,
 947          This->DriverBindingHandle, DeviceHandle);
 948
 949   FreePool (Dev);
 950
 951   return EFI_SUCCESS;
 952 }
 953
 954
 955 //
 956 // The static object that groups the Supported() (ie. probe), Start() and
 957 // Stop() functions of the driver together. Refer to UEFI Spec 2.3.1 + Errata
 958 // C, 10.1 EFI Driver Binding Protocol.
 959 //
 960 STATIC EFI_DRIVER_BINDING_PROTOCOL gDriverBinding = {
 961   &VirtioBlkDriverBindingSupported,
 962   &VirtioBlkDriverBindingStart,
 963   &VirtioBlkDriverBindingStop,
 964   0x10, // Version, must be in [0x10 .. 0xFFFFFFEF] for IHV-developed drivers
 965   NULL, // ImageHandle, to be overwritten by
 966         // EfiLibInstallDriverBindingComponentName2() in VirtioBlkEntryPoint()
 967   NULL  // DriverBindingHandle, ditto
 968 };
 969
 970
 971 //
 972 // The purpose of the following scaffolding (EFI_COMPONENT_NAME_PROTOCOL and
 973 // EFI_COMPONENT_NAME2_PROTOCOL implementation) is to format the driver's name
 974 // in English, for display on standard console devices. This is recommended for
 975 // UEFI drivers that follow the UEFI Driver Model. Refer to the Driver Writer's
 976 // Guide for UEFI 2.3.1 v1.01, 11 UEFI Driver and Controller Names.
 977 //
 978 // Device type names ("Virtio Block Device") are not formatted because the
 979 // driver supports only that device type. Therefore the driver name suffices
 980 // for unambiguous identification.
 981 //
 982
 983 STATIC
 984 EFI_UNICODE_STRING_TABLE mDriverNameTable[] = {
 985   { "eng;en", L"Virtio Block Driver" },
 986   { NULL,     NULL                   }
 987 };
 988
 989 STATIC
 990 EFI_COMPONENT_NAME_PROTOCOL gComponentName;
 991
 992 EFI_STATUS
 993 EFIAPI
 994 VirtioBlkGetDriverName (
 995   IN  EFI_COMPONENT_NAME_PROTOCOL *This,
 996   IN  CHAR8                       *Language,
 997   OUT CHAR16                      **DriverName
 998   )
 999 {
1000   return LookupUnicodeString2 (
1001            Language,
1002            This->SupportedLanguages,
1003            mDriverNameTable,
1004            DriverName,
1005            (BOOLEAN)(This == &gComponentName) // Iso639Language
1006            );
1007 }
1008
1009 EFI_STATUS
1010 EFIAPI
1011 VirtioBlkGetDeviceName (
1012   IN  EFI_COMPONENT_NAME_PROTOCOL *This,
1013   IN  EFI_HANDLE                  DeviceHandle,
1014   IN  EFI_HANDLE                  ChildHandle,
1015   IN  CHAR8                       *Language,
1016   OUT CHAR16                      **ControllerName
1017   )
1018 {
1019   return EFI_UNSUPPORTED;
1020 }
1021
1022 STATIC
1023 EFI_COMPONENT_NAME_PROTOCOL gComponentName = {
1024   &VirtioBlkGetDriverName,
1025   &VirtioBlkGetDeviceName,
1026   "eng" // SupportedLanguages, ISO 639-2 language codes
1027 };
1028
1029 STATIC
1030 EFI_COMPONENT_NAME2_PROTOCOL gComponentName2 = {
1031   (EFI_COMPONENT_NAME2_GET_DRIVER_NAME)     &VirtioBlkGetDriverName,
1032   (EFI_COMPONENT_NAME2_GET_CONTROLLER_NAME) &VirtioBlkGetDeviceName,
1033   "en" // SupportedLanguages, RFC 4646 language codes
1034 };
1035
1036
1037 //
1038 // Entry point of this driver.
1039 //
1040 EFI_STATUS
1041 EFIAPI
1042 VirtioBlkEntryPoint (
1043   IN EFI_HANDLE       ImageHandle,
1044   IN EFI_SYSTEM_TABLE *SystemTable
1045   )
1046 {
1047   return EfiLibInstallDriverBindingComponentName2 (
1048            ImageHandle,
1049            SystemTable,
1050            &gDriverBinding,
1051            ImageHandle,
1052            &gComponentName,
1053            &gComponentName2
1054            );
1055 }
1056