OvmfPkg/AmdSevDxe/AmdSevDxe.c

   1 /** @file
   2
   3   AMD Sev Dxe driver. This driver is dispatched early in DXE, due to being list
   4   in APRIORI. It clears C-bit from MMIO and NonExistent Memory space when SEV
   5   is enabled.
   6
   7   Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
   8
   9   This program and the accompanying materials are licensed and made available
  10   under the terms and conditions of the BSD License which accompanies this
  11   distribution.  The full text of the license may be found at
  12   http://opensource.org/licenses/bsd-license.php
  13
  14   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
  15   WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  16
  17 **/
  18
  19 #include <PiDxe.h>
  20
  21 #include <Library/BaseLib.h>
  22 #include <Library/DebugLib.h>
  23 #include <Library/BaseMemoryLib.h>
  24 #include <Library/MemoryAllocationLib.h>
  25 #include <Library/UefiBootServicesTableLib.h>
  26 #include <Library/DxeServicesTableLib.h>
  27 #include <Library/MemEncryptSevLib.h>
  28
  29 EFI_STATUS
  30 EFIAPI
  31 AmdSevDxeEntryPoint (
  32   IN EFI_HANDLE         ImageHandle,
  33   IN EFI_SYSTEM_TABLE   *SystemTable
  34   )
  35 {
  36   EFI_STATUS                       Status;
  37   EFI_GCD_MEMORY_SPACE_DESCRIPTOR  *AllDescMap;
  38   UINTN                            NumEntries;
  39   UINTN                            Index;
  40
  41   //
  42   // Do nothing when SEV is not enabled
  43   //
  44   if (!MemEncryptSevIsEnabled ()) {
  45     return EFI_UNSUPPORTED;
  46   }
  47
  48   //
  49   // Iterate through the GCD map and clear the C-bit from MMIO and NonExistent
  50   // memory space. The NonExistent memory space will be used for mapping the
  51   // MMIO space added later (eg PciRootBridge). By clearing both known MMIO and
  52   // NonExistent memory space can gurantee that current and furture MMIO adds
  53   // will have C-bit cleared.
  54   //
  55   Status = gDS->GetMemorySpaceMap (&NumEntries, &AllDescMap);
  56   if (!EFI_ERROR (Status)) {
  57     for (Index = 0; Index < NumEntries; Index++) {
  58       CONST EFI_GCD_MEMORY_SPACE_DESCRIPTOR *Desc;
  59
  60       Desc = &AllDescMap[Index];
  61       if (Desc->GcdMemoryType == EfiGcdMemoryTypeMemoryMappedIo ||
  62           Desc->GcdMemoryType == EfiGcdMemoryTypeNonExistent) {
  63         Status = MemEncryptSevClearPageEncMask (
  64                    0,
  65                    Desc->BaseAddress,
  66                    EFI_SIZE_TO_PAGES (Desc->Length),
  67                    FALSE
  68                    );
  69         ASSERT_EFI_ERROR (Status);
  70       }
  71     }
  72
  73     FreePool (AllDescMap);
  74   }
  75
  76   return EFI_SUCCESS;
  77 }