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 <Library/BaseLib.h>
  20 #include <Library/BaseMemoryLib.h>
  21 #include <Library/DebugLib.h>
  22 #include <Library/DxeServicesTableLib.h>
  23 #include <Library/MemEncryptSevLib.h>
  24 #include <Library/MemoryAllocationLib.h>
  25 #include <Library/UefiBootServicesTableLib.h>
  26 #include <PiDxe.h>
  27
  28 EFI_STATUS
  29 EFIAPI
  30 AmdSevDxeEntryPoint (
  31   IN EFI_HANDLE         ImageHandle,
  32   IN EFI_SYSTEM_TABLE   *SystemTable
  33   )
  34 {
  35   EFI_STATUS                       Status;
  36   EFI_GCD_MEMORY_SPACE_DESCRIPTOR  *AllDescMap;
  37   UINTN                            NumEntries;
  38   UINTN                            Index;
  39
  40   //
  41   // Do nothing when SEV is not enabled
  42   //
  43   if (!MemEncryptSevIsEnabled ()) {
  44     return EFI_UNSUPPORTED;
  45   }
  46
  47   //
  48   // Iterate through the GCD map and clear the C-bit from MMIO and NonExistent
  49   // memory space. The NonExistent memory space will be used for mapping the
  50   // MMIO space added later (eg PciRootBridge). By clearing both known MMIO and
  51   // NonExistent memory space can gurantee that current and furture MMIO adds
  52   // will have C-bit cleared.
  53   //
  54   Status = gDS->GetMemorySpaceMap (&NumEntries, &AllDescMap);
  55   if (!EFI_ERROR (Status)) {
  56     for (Index = 0; Index < NumEntries; Index++) {
  57       CONST EFI_GCD_MEMORY_SPACE_DESCRIPTOR *Desc;
  58
  59       Desc = &AllDescMap[Index];
  60       if (Desc->GcdMemoryType == EfiGcdMemoryTypeMemoryMappedIo ||
  61           Desc->GcdMemoryType == EfiGcdMemoryTypeNonExistent) {
  62         Status = MemEncryptSevClearPageEncMask (
  63                    0,
  64                    Desc->BaseAddress,
  65                    EFI_SIZE_TO_PAGES (Desc->Length),
  66                    FALSE
  67                    );
  68         ASSERT_EFI_ERROR (Status);
  69       }
  70     }
  71
  72     FreePool (AllDescMap);
  73   }
  74
  75   return EFI_SUCCESS;
  76 }