summaryrefslogtreecommitdiff
path: root/OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.c
blob: 72efba091045acb7791586ff9ba1e8a46087ce25 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
/** @file
  Firmware Block Services to support emulating non-volatile variables
  by pretending that a memory buffer is storage for the NV variables.

  Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
  This program and the accompanying materials
  are licensed and made available under the terms and conditions of the BSD License
  which accompanies this distribution.  The full text of the license may be found at
  http://opensource.org/licenses/bsd-license.php

  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include "PiDxe.h"
#include <Guid/EventGroup.h>
#include <Guid/SystemNvDataGuid.h>
#include <Guid/VariableFormat.h>

#include <Protocol/FirmwareVolumeBlock.h>
#include <Protocol/DevicePath.h>

#include <Library/UefiLib.h>
#include <Library/UefiDriverEntryPoint.h>
#include <Library/BaseLib.h>
#include <Library/UefiRuntimeLib.h>
#include <Library/DebugLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/DevicePathLib.h>
#include <Library/PcdLib.h>
#include <Library/PlatformFvbLib.h>
#include "Fvb.h"

#define EFI_AUTHENTICATED_VARIABLE_GUID \
{ 0xaaf32c78, 0x947b, 0x439a, { 0xa1, 0x80, 0x2e, 0x14, 0x4e, 0xc3, 0x77, 0x92 } }

//
// Virtual Address Change Event
//
// This is needed for runtime variable access.
//
EFI_EVENT   mEmuVarsFvbAddrChangeEvent = NULL;

//
// This is the single instance supported by this driver.  It
// supports the FVB and Device Path protocols.
//
EFI_FW_VOL_BLOCK_DEVICE mEmuVarsFvb = {
  FVB_DEVICE_SIGNATURE,
  {     // DevicePath
    {
      {
        HARDWARE_DEVICE_PATH,
        HW_MEMMAP_DP,
        {
          sizeof (MEMMAP_DEVICE_PATH),
          0
        }
      },
      EfiMemoryMappedIO,
      0,
      0,
    },
    {
      END_DEVICE_PATH_TYPE,
      END_ENTIRE_DEVICE_PATH_SUBTYPE,
      {
        sizeof (EFI_DEVICE_PATH_PROTOCOL),
        0
      }
    }
  },
  NULL, // BufferPtr
  FixedPcdGet32 (PcdFlashNvStorageFtwSpareSize), // BlockSize
  2 * FixedPcdGet32 (PcdFlashNvStorageFtwSpareSize), // Size
  {     // FwVolBlockInstance
    FvbProtocolGetAttributes,
    FvbProtocolSetAttributes,
    FvbProtocolGetPhysicalAddress,
    FvbProtocolGetBlockSize,
    FvbProtocolRead,
    FvbProtocolWrite,
    FvbProtocolEraseBlocks,
    NULL
  },
};


/**
  Notification function of EVT_SIGNAL_VIRTUAL_ADDRESS_CHANGE.

  This is a notification function registered on EVT_SIGNAL_VIRTUAL_ADDRESS_CHANGE event.
  It converts pointer to new virtual address.

  @param  Event        Event whose notification function is being invoked.
  @param  Context      Pointer to the notification function's context.

**/
VOID
EFIAPI
FvbVirtualAddressChangeEvent (
  IN EFI_EVENT        Event,
  IN VOID             *Context
  )
{
  EfiConvertPointer (0x0, &mEmuVarsFvb.BufferPtr);
}


//
// FVB protocol APIs
//

/**
  The GetPhysicalAddress() function retrieves the base address of
  a memory-mapped firmware volume. This function should be called
  only for memory-mapped firmware volumes.

  @param This     Indicates the EFI_FIRMWARE_VOLUME_BLOCK2_PROTOCOL instance.
  
  @param Address  Pointer to a caller-allocated
                  EFI_PHYSICAL_ADDRESS that, on successful
                  return from GetPhysicalAddress(), contains the
                  base address of the firmware volume.
  
  @retval EFI_SUCCESS       The firmware volume base address is returned.
  
  @retval EFI_NOT_SUPPORTED The firmware volume is not memory mapped.

**/
EFI_STATUS
EFIAPI
FvbProtocolGetPhysicalAddress (
  IN CONST  EFI_FIRMWARE_VOLUME_BLOCK2_PROTOCOL *This,
  OUT       EFI_PHYSICAL_ADDRESS                *Address
  )
{
  EFI_FW_VOL_BLOCK_DEVICE *FvbDevice;

  FvbDevice = FVB_DEVICE_FROM_THIS (This);

  *Address = (EFI_PHYSICAL_ADDRESS)(UINTN) FvbDevice->BufferPtr;

  return EFI_SUCCESS;
}


/**
  The GetBlockSize() function retrieves the size of the requested
  block. It also returns the number of additional blocks with
  the identical size. The GetBlockSize() function is used to
  retrieve the block map (see EFI_FIRMWARE_VOLUME_HEADER).


  @param This           Indicates the EFI_FIRMWARE_VOLUME_BLOCK2_PROTOCOL instance.

  @param Lba            Indicates the block for which to return the size.

  @param BlockSize      Pointer to a caller-allocated UINTN in which
                        the size of the block is returned.

  @param NumberOfBlocks Pointer to a caller-allocated UINTN in
                        which the number of consecutive blocks,
                        starting with Lba, is returned. All
                        blocks in this range have a size of
                        BlockSize.

  
  @retval EFI_SUCCESS             The firmware volume base address is returned.
  
  @retval EFI_INVALID_PARAMETER   The requested LBA is out of range.

**/
EFI_STATUS
EFIAPI
FvbProtocolGetBlockSize (
  IN CONST  EFI_FIRMWARE_VOLUME_BLOCK2_PROTOCOL *This,
  IN        EFI_LBA                             Lba,
  OUT       UINTN                               *BlockSize,
  OUT       UINTN                               *NumberOfBlocks
  )
{
  EFI_FW_VOL_BLOCK_DEVICE *FvbDevice;

  if (Lba > 1) {
    return EFI_INVALID_PARAMETER;
  }

  FvbDevice = FVB_DEVICE_FROM_THIS (This);

  *BlockSize = FvbDevice->BlockSize;
  *NumberOfBlocks = (UINTN) (2 - (UINTN) Lba);

  return EFI_SUCCESS;
}


/**
  The GetAttributes() function retrieves the attributes and
  current settings of the block. Status Codes Returned

  @param This       Indicates the EFI_FIRMWARE_VOLUME_BLOCK2_PROTOCOL instance.

  @param Attributes Pointer to EFI_FVB_ATTRIBUTES_2 in which the
                    attributes and current settings are
                    returned. Type EFI_FVB_ATTRIBUTES_2 is defined
                    in EFI_FIRMWARE_VOLUME_HEADER.

  @retval EFI_SUCCESS The firmware volume attributes were
                      returned.

**/
EFI_STATUS
EFIAPI
FvbProtocolGetAttributes (
  IN CONST  EFI_FIRMWARE_VOLUME_BLOCK2_PROTOCOL *This,
  OUT       EFI_FVB_ATTRIBUTES_2                *Attributes
  )
{
  *Attributes =
    (EFI_FVB_ATTRIBUTES_2) (
      EFI_FVB2_READ_ENABLED_CAP |
      EFI_FVB2_READ_STATUS |
      EFI_FVB2_WRITE_ENABLED_CAP |
      EFI_FVB2_WRITE_STATUS |
      EFI_FVB2_ERASE_POLARITY
      );

  return EFI_SUCCESS;
}


/**
  The SetAttributes() function sets configurable firmware volume
  attributes and returns the new settings of the firmware volume.

  @param This         Indicates the EFI_FIRMWARE_VOLUME_BLOCK2_PROTOCOL instance.

  @param Attributes   On input, Attributes is a pointer to
                      EFI_FVB_ATTRIBUTES_2 that contains the
                      desired firmware volume settings. On
                      successful return, it contains the new
                      settings of the firmware volume. Type
                      EFI_FVB_ATTRIBUTES_2 is defined in
                      EFI_FIRMWARE_VOLUME_HEADER.
  
  @retval EFI_SUCCESS           The firmware volume attributes were returned.

  @retval EFI_INVALID_PARAMETER The attributes requested are in
                                conflict with the capabilities
                                as declared in the firmware
                                volume header.

**/
EFI_STATUS
EFIAPI
FvbProtocolSetAttributes (
  IN CONST  EFI_FIRMWARE_VOLUME_BLOCK2_PROTOCOL *This,
  IN OUT    EFI_FVB_ATTRIBUTES_2                *Attributes
  )
{
  return EFI_ACCESS_DENIED;
}


/**
  Erases and initializes a firmware volume block.

  The EraseBlocks() function erases one or more blocks as denoted
  by the variable argument list. The entire parameter list of
  blocks must be verified before erasing any blocks. If a block is
  requested that does not exist within the associated firmware
  volume (it has a larger index than the last block of the
  firmware volume), the EraseBlocks() function must return the
  status code EFI_INVALID_PARAMETER without modifying the contents
  of the firmware volume. Implementations should be mindful that
  the firmware volume might be in the WriteDisabled state. If it
  is in this state, the EraseBlocks() function must return the
  status code EFI_ACCESS_DENIED without modifying the contents of
  the firmware volume. All calls to EraseBlocks() must be fully
  flushed to the hardware before the EraseBlocks() service
  returns.

  @param This   Indicates the EFI_FIRMWARE_VOLUME_BLOCK2_PROTOCOL
                instance.

  @param ...    The variable argument list is a list of tuples.
                Each tuple describes a range of LBAs to erase
                and consists of the following:
                - An EFI_LBA that indicates the starting LBA
                - A UINTN that indicates the number of blocks to
                  erase

                The list is terminated with an
                EFI_LBA_LIST_TERMINATOR. For example, the
                following indicates that two ranges of blocks
                (5-7 and 10-11) are to be erased: EraseBlocks
                (This, 5, 3, 10, 2, EFI_LBA_LIST_TERMINATOR);

  @retval EFI_SUCCESS The erase request was successfully
                      completed.
  
  @retval EFI_ACCESS_DENIED   The firmware volume is in the
                              WriteDisabled state.
  @retval EFI_DEVICE_ERROR  The block device is not functioning
                            correctly and could not be written.
                            The firmware device may have been
                            partially erased.
  @retval EFI_INVALID_PARAMETER One or more of the LBAs listed
                                in the variable argument list do
                                not exist in the firmware volume.  

**/
EFI_STATUS
EFIAPI
FvbProtocolEraseBlocks (
  IN CONST  EFI_FIRMWARE_VOLUME_BLOCK2_PROTOCOL *This,
  ...
  )
{
  EFI_FW_VOL_BLOCK_DEVICE *FvbDevice;
  VA_LIST                 args;
  EFI_LBA                 StartingLba;
  UINTN                   NumOfLba;
  UINT8                   Erase;
  VOID                    *ErasePtr;
  UINTN                   EraseSize;

  FvbDevice = FVB_DEVICE_FROM_THIS (This);
  Erase = 0;

  VA_START (args, This);

  do {
    StartingLba = VA_ARG (args, EFI_LBA);
    if (StartingLba == EFI_LBA_LIST_TERMINATOR) {
      break;
    }

    NumOfLba = VA_ARG (args, UINT32);

    //
    // Check input parameters
    //
    if ((NumOfLba == 0) || (StartingLba > 1) || ((StartingLba + NumOfLba) > 2)) {
      VA_END (args);
      return EFI_INVALID_PARAMETER;
    }

    if (StartingLba == 0) {
      Erase = (UINT8) (Erase | BIT0);
    }
    if ((StartingLba + NumOfLba) == 2) {
      Erase = (UINT8) (Erase | BIT1);
    }

  } while (1);

  VA_END (args);

  ErasePtr = (UINT8*) FvbDevice->BufferPtr;
  EraseSize = 0;

  if ((Erase & BIT0) != 0) {
    EraseSize = EraseSize + FvbDevice->BlockSize;
  } else {
    ErasePtr = (VOID*) ((UINT8*)ErasePtr + FvbDevice->BlockSize);
  }

  if ((Erase & BIT1) != 0) {
    EraseSize = EraseSize + FvbDevice->BlockSize;
  }

  if (EraseSize != 0) {
    SetMem (
      (VOID*) ErasePtr,
      EraseSize,
      ERASED_UINT8
      );
    VA_START (args, This);
    PlatformFvbBlocksErased (This, args);
    VA_END (args);
  }

  return EFI_SUCCESS;
}


/**
  Writes the specified number of bytes from the input buffer to the block.

  The Write() function writes the specified number of bytes from
  the provided buffer to the specified block and offset. If the
  firmware volume is sticky write, the caller must ensure that
  all the bits of the specified range to write are in the
  EFI_FVB_ERASE_POLARITY state before calling the Write()
  function, or else the result will be unpredictable. This
  unpredictability arises because, for a sticky-write firmware
  volume, a write may negate a bit in the EFI_FVB_ERASE_POLARITY
  state but cannot flip it back again. In general, before
  calling the Write() function, the caller should call the
  EraseBlocks() function first to erase the specified block to
  write. A block erase cycle will transition bits from the
  (NOT)EFI_FVB_ERASE_POLARITY state back to the
  EFI_FVB_ERASE_POLARITY state. Implementations should be
  mindful that the firmware volume might be in the WriteDisabled
  state. If it is in this state, the Write() function must
  return the status code EFI_ACCESS_DENIED without modifying the
  contents of the firmware volume. The Write() function must
  also prevent spanning block boundaries. If a write is
  requested that spans a block boundary, the write must store up
  to the boundary but not beyond. The output parameter NumBytes
  must be set to correctly indicate the number of bytes actually
  written. The caller must be aware that a write may be
  partially completed. All writes, partial or otherwise, must be
  fully flushed to the hardware before the Write() service
  returns.

  @param This     Indicates the EFI_FIRMWARE_VOLUME_BLOCK2_PROTOCOL instance.
  
  @param Lba      The starting logical block index to write to.
  
  @param Offset   Offset into the block at which to begin writing.
  
  @param NumBytes Pointer to a UINTN. At entry, *NumBytes
                  contains the total size of the buffer. At
                  exit, *NumBytes contains the total number of
                  bytes actually written.
  
  @param Buffer   Pointer to a caller-allocated buffer that
                  contains the source for the write.
  
  @retval EFI_SUCCESS         The firmware volume was written successfully.
  
  @retval EFI_BAD_BUFFER_SIZE The write was attempted across an
                              LBA boundary. On output, NumBytes
                              contains the total number of bytes
                              actually written.
  
  @retval EFI_ACCESS_DENIED   The firmware volume is in the
                              WriteDisabled state.
  
  @retval EFI_DEVICE_ERROR    The block device is malfunctioning
                              and could not be written.


**/
EFI_STATUS
EFIAPI
FvbProtocolWrite (
  IN CONST  EFI_FIRMWARE_VOLUME_BLOCK2_PROTOCOL *This,
  IN        EFI_LBA                             Lba,
  IN        UINTN                               Offset,
  IN OUT    UINTN                               *NumBytes,
  IN        UINT8                               *Buffer
  )
{

  EFI_FW_VOL_BLOCK_DEVICE *FvbDevice;
  UINT8                   *FvbDataPtr;

  FvbDevice = FVB_DEVICE_FROM_THIS (This);

  if ((Lba > 1) || (Offset > FvbDevice->BlockSize)) {
    return EFI_INVALID_PARAMETER;
  }

  if ((Offset + *NumBytes) > FvbDevice->BlockSize) {
    *NumBytes = FvbDevice->BlockSize - Offset;
  }

  FvbDataPtr =
    (UINT8*) FvbDevice->BufferPtr +
    MultU64x32 (Lba, (UINT32) FvbDevice->BlockSize) +
    Offset;

  if (*NumBytes > 0) {
    CopyMem (FvbDataPtr, Buffer, *NumBytes);
    PlatformFvbDataWritten (This, Lba, Offset, *NumBytes, Buffer);
  }

  return EFI_SUCCESS;
}


/**
  Reads the specified number of bytes into a buffer from the specified block.

  The Read() function reads the requested number of bytes from the
  requested block and stores them in the provided buffer.
  Implementations should be mindful that the firmware volume
  might be in the ReadDisabled state. If it is in this state,
  the Read() function must return the status code
  EFI_ACCESS_DENIED without modifying the contents of the
  buffer. The Read() function must also prevent spanning block
  boundaries. If a read is requested that would span a block
  boundary, the read must read up to the boundary but not
  beyond. The output parameter NumBytes must be set to correctly
  indicate the number of bytes actually read. The caller must be
  aware that a read may be partially completed.

  @param This     Indicates the EFI_FIRMWARE_VOLUME_BLOCK2_PROTOCOL instance.
  
  @param Lba      The starting logical block index
                  from which to read.

  @param Offset   Offset into the block at which to begin reading.

  @param NumBytes Pointer to a UINTN. At entry, *NumBytes
                  contains the total size of the buffer. At
                  exit, *NumBytes contains the total number of
                  bytes read.

  @param Buffer   Pointer to a caller-allocated buffer that will
                  be used to hold the data that is read.

  @retval EFI_SUCCESS         The firmware volume was read successfully
                              and contents are in Buffer.
  
  @retval EFI_BAD_BUFFER_SIZE Read attempted across an LBA
                              boundary. On output, NumBytes
                              contains the total number of bytes
                              returned in Buffer.
  
  @retval EFI_ACCESS_DENIED   The firmware volume is in the
                              ReadDisabled state.
  
  @retval EFI_DEVICE_ERROR    The block device is not
                              functioning correctly and could
                              not be read.

**/
EFI_STATUS
EFIAPI
FvbProtocolRead (
  IN CONST  EFI_FIRMWARE_VOLUME_BLOCK2_PROTOCOL *This,
  IN        EFI_LBA                             Lba,
  IN        UINTN                               Offset,
  IN OUT    UINTN                               *NumBytes,
  IN OUT    UINT8                               *Buffer
  )
{
  EFI_FW_VOL_BLOCK_DEVICE *FvbDevice;
  UINT8                   *FvbDataPtr;

  FvbDevice = FVB_DEVICE_FROM_THIS (This);

  if ((Lba > 1) || (Offset > FvbDevice->BlockSize)) {
    return EFI_INVALID_PARAMETER;
  }

  if ((Offset + *NumBytes) > FvbDevice->BlockSize) {
    *NumBytes = FvbDevice->BlockSize - Offset;
  }

  FvbDataPtr =
    (UINT8*) FvbDevice->BufferPtr +
    MultU64x32 (Lba, (UINT32) FvbDevice->BlockSize) +
    Offset;

  if (*NumBytes > 0) {
    CopyMem (Buffer, FvbDataPtr, *NumBytes);
    PlatformFvbDataRead (This, Lba, Offset, *NumBytes, Buffer);
  }

  return EFI_SUCCESS;
}


/**
  Check the integrity of firmware volume header.

  @param[in] FwVolHeader - A pointer to a firmware volume header

  @retval  EFI_SUCCESS   - The firmware volume is consistent
  @retval  EFI_NOT_FOUND - The firmware volume has been corrupted.

**/
EFI_STATUS
ValidateFvHeader (
  IN EFI_FIRMWARE_VOLUME_HEADER   *FwVolHeader
  )
{
  UINT16  Checksum;

  //
  // Verify the header revision, header signature, length
  // Length of FvBlock cannot be 2**64-1
  // HeaderLength cannot be an odd number
  //
  if ((FwVolHeader->Revision != EFI_FVH_REVISION) ||
      (FwVolHeader->Signature != EFI_FVH_SIGNATURE) ||
      (FwVolHeader->FvLength != EMU_FVB_SIZE) ||
      (FwVolHeader->HeaderLength != EMU_FV_HEADER_LENGTH)
      ) {
    DEBUG ((EFI_D_INFO, "EMU Variable FVB: Basic FV headers were invalid\n"));
    return EFI_NOT_FOUND;
  }
  //
  // Verify the header checksum
  //
  Checksum = CalculateSum16((VOID*) FwVolHeader, FwVolHeader->HeaderLength);

  if (Checksum != 0) {
    DEBUG ((EFI_D_INFO, "EMU Variable FVB: FV checksum was invalid\n"));
    return EFI_NOT_FOUND;
  }

  return EFI_SUCCESS;
}


/**
  Initializes the FV Header and Variable Store Header
  to support variable operations.

  @param[in]  Ptr - Location to initialize the headers

**/
VOID
InitializeFvAndVariableStoreHeaders (
  IN  VOID   *Ptr
  )
{
  //
  // Templates for standard (non-authenticated) variable FV header
  //
  STATIC FVB_FV_HDR_AND_VARS_TEMPLATE FvAndVarTemplate = {
    { // EFI_FIRMWARE_VOLUME_HEADER FvHdr;
      // UINT8                     ZeroVector[16];
      { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },

      // EFI_GUID                  FileSystemGuid;
      EFI_SYSTEM_NV_DATA_FV_GUID,

      // UINT64                    FvLength;
      EMU_FVB_SIZE,

      // UINT32                    Signature;
      EFI_FVH_SIGNATURE,

      // EFI_FVB_ATTRIBUTES_2      Attributes;
      0x4feff,

      // UINT16                    HeaderLength;
      EMU_FV_HEADER_LENGTH,

      // UINT16                    Checksum;
      0,

      // UINT16                    ExtHeaderOffset;
      0,

      // UINT8                     Reserved[1];
      {0},

      // UINT8                     Revision;
      EFI_FVH_REVISION,

      // EFI_FV_BLOCK_MAP_ENTRY    BlockMap[1];
      { 
        {
          2, // UINT32 NumBlocks;
          EMU_FVB_BLOCK_SIZE  // UINT32 Length;
        }
      }
    },
    // EFI_FV_BLOCK_MAP_ENTRY     EndBlockMap;
    { 0, 0 }, // End of block map
    { // VARIABLE_STORE_HEADER      VarHdr;
      // EFI_GUID  Signature;
      EFI_VARIABLE_GUID,

      // UINT32  Size;
      (
        FixedPcdGet32 (PcdVariableStoreSize) -
        OFFSET_OF (FVB_FV_HDR_AND_VARS_TEMPLATE, VarHdr)
      ),

      // UINT8   Format;
      VARIABLE_STORE_FORMATTED,

      // UINT8   State;
      VARIABLE_STORE_HEALTHY,

      // UINT16  Reserved;
      0,

      // UINT32  Reserved1;
      0
    }
  };

  //
  // Templates for authenticated variable FV header
  //
  STATIC FVB_FV_HDR_AND_VARS_TEMPLATE FvAndAuthenticatedVarTemplate = {
    { // EFI_FIRMWARE_VOLUME_HEADER FvHdr;
      // UINT8                     ZeroVector[16];
      { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },

      // EFI_GUID                  FileSystemGuid;
      EFI_SYSTEM_NV_DATA_FV_GUID,

      // UINT64                    FvLength;
      EMU_FVB_SIZE,

      // UINT32                    Signature;
      EFI_FVH_SIGNATURE,

      // EFI_FVB_ATTRIBUTES_2      Attributes;
      0x4feff,

      // UINT16                    HeaderLength;
      EMU_FV_HEADER_LENGTH,

      // UINT16                    Checksum;
      0,

      // UINT16                    ExtHeaderOffset;
      0,

      // UINT8                     Reserved[1];
      {0},

      // UINT8                     Revision;
      EFI_FVH_REVISION,

      // EFI_FV_BLOCK_MAP_ENTRY    BlockMap[1];
      {
        {
          2, // UINT32 NumBlocks;
          EMU_FVB_BLOCK_SIZE  // UINT32 Length;
        }
      }
    },
    // EFI_FV_BLOCK_MAP_ENTRY     EndBlockMap;
    { 0, 0 }, // End of block map
    { // VARIABLE_STORE_HEADER      VarHdr;
        // EFI_GUID  Signature;     // need authenticated variables for secure boot
        EFI_AUTHENTICATED_VARIABLE_GUID,

      // UINT32  Size;
      (
        FixedPcdGet32 (PcdVariableStoreSize) -
        OFFSET_OF (FVB_FV_HDR_AND_VARS_TEMPLATE, VarHdr)
      ),

      // UINT8   Format;
      VARIABLE_STORE_FORMATTED,

      // UINT8   State;
      VARIABLE_STORE_HEALTHY,

      // UINT16  Reserved;
      0,

      // UINT32  Reserved1;
      0
    }
  };

  EFI_FIRMWARE_VOLUME_HEADER  *Fv;

  //
  // Copy the template structure into the location
  //
  if (FeaturePcdGet (PcdSecureBootEnable) == FALSE) {
    CopyMem (Ptr, (VOID*)&FvAndVarTemplate, sizeof (FvAndVarTemplate));
  } else {
    CopyMem (Ptr, (VOID*)&FvAndAuthenticatedVarTemplate, sizeof (FvAndAuthenticatedVarTemplate));
  }

  //
  // Update the checksum for the FV header
  //
  Fv = (EFI_FIRMWARE_VOLUME_HEADER*) Ptr;
  Fv->Checksum = CalculateCheckSum16 (Ptr, Fv->HeaderLength);
}


/**
  Initializes the Fault Tolerant Write data structure

  This data structure is used by the Fault Tolerant Write driver.

  @param[in]  Buffer - Location for the FTW data structure

**/
VOID
InitializeFtwState (
  IN  VOID   *Buffer
  )
{
  EFI_FAULT_TOLERANT_WORKING_BLOCK_HEADER *Hdr;
  UINT32                                  TempCrc;
  STATIC EFI_FAULT_TOLERANT_WORKING_BLOCK_HEADER DefaultFtw = {
    EFI_SYSTEM_NV_DATA_FV_GUID, // EFI_GUID  Signature;
    ERASED_UINT32,              // UINT32    Crc;
    ERASED_BIT,                 // UINT8     WorkingBlockValid : 1;
    ERASED_BIT,                 // UINT8     WorkingBlockInvalid : 1;
    0,                          // UINT8     Reserved : 6;
    { 0, 0, 0 },                // UINT8     Reserved3[3];
    FTW_WRITE_QUEUE_SIZE        // UINT64    WriteQueueSize;
  };

  CopyMem (Buffer, (VOID*) &DefaultFtw, sizeof (DefaultFtw));

  Hdr = (EFI_FAULT_TOLERANT_WORKING_BLOCK_HEADER*) Buffer;

  //
  // Calculate checksum.
  //
  // The Crc, WorkingBlockValid and WorkingBlockInvalid bits should
  // be set to the erased state before computing the checksum.
  //
  gBS->CalculateCrc32 (Buffer, sizeof (DefaultFtw), &TempCrc);
  Hdr->Crc = TempCrc;

  //
  // Mark as valid.
  //
  Hdr->WorkingBlockValid = NOT_ERASED_BIT;
}


/**
  Main entry point.

  @param[in] ImageHandle    The firmware allocated handle for the EFI image.  
  @param[in] SystemTable    A pointer to the EFI System Table.
  
  @retval EFI_SUCCESS       Successfully initialized.

**/
EFI_STATUS
EFIAPI
FvbInitialize (
  IN EFI_HANDLE         ImageHandle,
  IN EFI_SYSTEM_TABLE   *SystemTable
  )
{
  EFI_STATUS                          Status;
  VOID                                *Ptr;
  VOID                                *SubPtr;
  BOOLEAN                             Initialize;
  EFI_HANDLE                          Handle;
  EFI_PHYSICAL_ADDRESS                Address;

  DEBUG ((EFI_D_INFO, "EMU Variable FVB Started\n"));

  //
  // Verify that the PCD's are set correctly.
  //
  if (
       (PcdGet32 (PcdVariableStoreSize) +
        PcdGet32 (PcdFlashNvStorageFtwWorkingSize)
       ) >
       EMU_FVB_BLOCK_SIZE
     ) {
    DEBUG ((EFI_D_ERROR, "EMU Variable invalid PCD sizes\n"));
    return EFI_INVALID_PARAMETER;
  }

  //
  // By default we will initialize the FV contents.  But, if
  // PcdEmuVariableNvStoreReserved is non-zero, then we will
  // use this location for our buffer.
  //
  // If this location does not have a proper FV header, then
  // we will initialize it.
  //
  Initialize = TRUE;
  if (PcdGet64 (PcdEmuVariableNvStoreReserved) != 0) {
    Ptr = (VOID*)(UINTN) PcdGet64 (PcdEmuVariableNvStoreReserved);
    DEBUG ((
      EFI_D_INFO,
      "EMU Variable FVB: Using pre-reserved block at %p\n",
      Ptr
      ));
    Status = ValidateFvHeader (Ptr);
    if (!EFI_ERROR (Status)) {
      DEBUG ((EFI_D_INFO, "EMU Variable FVB: Found valid pre-existing FV\n"));
      Initialize = FALSE;
    }
  } else {
    Ptr = AllocateAlignedRuntimePages (
            EFI_SIZE_TO_PAGES (EMU_FVB_SIZE),
            SIZE_64KB
            );
  }

  mEmuVarsFvb.BufferPtr = Ptr;

  //
  // Initialize the main FV header and variable store header
  //
  if (Initialize) {
    SetMem (Ptr, EMU_FVB_SIZE, ERASED_UINT8);
    InitializeFvAndVariableStoreHeaders (Ptr);
  }
  PcdSet64 (PcdFlashNvStorageVariableBase64, (UINT32)(UINTN) Ptr);

  //
  // Initialize the Fault Tolerant Write data area
  //
  SubPtr = (VOID*) ((UINT8*) Ptr + PcdGet32 (PcdVariableStoreSize));
  if (Initialize) {
    InitializeFtwState (SubPtr);
  }
  PcdSet32 (PcdFlashNvStorageFtwWorkingBase, (UINT32)(UINTN) SubPtr);

  //
  // Initialize the Fault Tolerant Write spare block
  //
  SubPtr = (VOID*) ((UINT8*) Ptr + EMU_FVB_BLOCK_SIZE);
  PcdSet32 (PcdFlashNvStorageFtwSpareBase, (UINT32)(UINTN) SubPtr);

  //
  // Setup FVB device path
  //
  Address = (EFI_PHYSICAL_ADDRESS)(UINTN) Ptr;
  mEmuVarsFvb.DevicePath.MemMapDevPath.StartingAddress = Address;
  mEmuVarsFvb.DevicePath.MemMapDevPath.EndingAddress = Address + EMU_FVB_SIZE - 1;

  //
  // Install the protocols
  //
  DEBUG ((EFI_D_INFO, "Installing FVB for EMU Variable support\n"));
  Handle = 0;
  Status = gBS->InstallMultipleProtocolInterfaces (
                  &Handle,
                  &gEfiFirmwareVolumeBlock2ProtocolGuid,
                  &mEmuVarsFvb.FwVolBlockInstance,
                  &gEfiDevicePathProtocolGuid,
                  &mEmuVarsFvb.DevicePath,
                  NULL
                  );
  ASSERT_EFI_ERROR (Status);

  //
  // Register for the virtual address change event
  //
  Status = gBS->CreateEventEx (
                  EVT_NOTIFY_SIGNAL,
                  TPL_NOTIFY,
                  FvbVirtualAddressChangeEvent,
                  NULL,
                  &gEfiEventVirtualAddressChangeGuid,
                  &mEmuVarsFvbAddrChangeEvent
                  );
  ASSERT_EFI_ERROR (Status);

  return EFI_SUCCESS;
}