OvmfPkg: MemEncryptSevLib: Add Null instance

This change introduces a Null instance of MemEncryptSevLib to enable
platforms that do not have confidential compute support.

Signed-off-by: Kun Qin <kun.qin@microsoft.com>

2 files changed, 273 insertions, 0 deletions

diff --git a/OvmfPkg/Library/MemEncryptSevLibNull/MemEncryptSevLibNull.c b/OvmfPkg/Library/MemEncryptSevLibNull/MemEncryptSevLibNull.c
new file mode 100644
index 0000000..e22aedc
--- /dev/null
+++ b/OvmfPkg/Library/MemEncryptSevLibNull/MemEncryptSevLibNull.c
@@ -0,0 +1,241 @@
+/** @file

+

+  Secure Encrypted Virtualization (SEV) library helper function

+

+  Copyright (c) 2017 - 2020, AMD Incorporated. All rights reserved.<BR>

+  Copyright (c) Microsoft Corporation.

+

+  SPDX-License-Identifier: BSD-2-Clause-Patent

+

+**/

+

+#include <Uefi.h>

+#include <Library/MemEncryptSevLib.h>

+

+/**

+  Returns a boolean to indicate whether SEV-SNP is enabled.

+

+  @retval TRUE           SEV-SNP is enabled

+  @retval FALSE          SEV-SNP is not enabled

+**/

+BOOLEAN

+EFIAPI

+MemEncryptSevSnpIsEnabled (

+  VOID

+  )

+{

+  return FALSE;

+}

+

+/**

+  Returns a boolean to indicate whether SEV-ES is enabled.

+

+  @retval TRUE           SEV-ES is enabled

+  @retval FALSE          SEV-ES is not enabled

+**/

+BOOLEAN

+EFIAPI

+MemEncryptSevEsIsEnabled (

+  VOID

+  )

+{

+  return FALSE;

+}

+

+/**

+  Returns a boolean to indicate whether SEV is enabled.

+

+  @retval TRUE           SEV is enabled

+  @retval FALSE          SEV is not enabled

+**/

+BOOLEAN

+EFIAPI

+MemEncryptSevIsEnabled (

+  VOID

+  )

+{

+  return FALSE;

+}

+

+/**

+  This function clears memory encryption bit for the memory region specified by

+  BaseAddress and NumPages from the current page table context.

+

+  @param[in]  Cr3BaseAddress          Cr3 Base Address (if zero then use

+                                      current CR3)

+  @param[in]  BaseAddress             The physical address that is the start

+                                      address of a memory region.

+  @param[in]  NumPages                The number of pages from start memory

+                                      region.

+

+  @retval RETURN_SUCCESS              The attributes were cleared for the

+                                      memory region.

+  @retval RETURN_INVALID_PARAMETER    Number of pages is zero.

+  @retval RETURN_UNSUPPORTED          Clearing the memory encryption attribute

+                                      is not supported

+**/

+RETURN_STATUS

+EFIAPI

+MemEncryptSevClearPageEncMask (

+  IN PHYSICAL_ADDRESS  Cr3BaseAddress,

+  IN PHYSICAL_ADDRESS  BaseAddress,

+  IN UINTN             NumPages

+  )

+{

+  return RETURN_UNSUPPORTED;

+}

+

+/**

+  This function sets memory encryption bit for the memory region specified by

+  BaseAddress and NumPages from the current page table context.

+

+  @param[in]  Cr3BaseAddress          Cr3 Base Address (if zero then use

+                                      current CR3)

+  @param[in]  BaseAddress             The physical address that is the start

+                                      address of a memory region.

+  @param[in]  NumPages                The number of pages from start memory

+                                      region.

+

+  @retval RETURN_SUCCESS              The attributes were set for the memory

+                                      region.

+  @retval RETURN_INVALID_PARAMETER    Number of pages is zero.

+  @retval RETURN_UNSUPPORTED          Setting the memory encryption attribute

+                                      is not supported

+**/

+RETURN_STATUS

+EFIAPI

+MemEncryptSevSetPageEncMask (

+  IN PHYSICAL_ADDRESS  Cr3BaseAddress,

+  IN PHYSICAL_ADDRESS  BaseAddress,

+  IN UINTN             NumPages

+  )

+{

+  return RETURN_UNSUPPORTED;

+}

+

+/**

+  Locate the page range that covers the initial (pre-SMBASE-relocation) SMRAM

+  Save State Map.

+

+  @param[out] BaseAddress     The base address of the lowest-address page that

+                              covers the initial SMRAM Save State Map.

+

+  @param[out] NumberOfPages   The number of pages in the page range that covers

+                              the initial SMRAM Save State Map.

+

+  @retval RETURN_SUCCESS      BaseAddress and NumberOfPages have been set on

+                              output.

+

+  @retval RETURN_UNSUPPORTED  SMM is unavailable.

+**/

+RETURN_STATUS

+EFIAPI

+MemEncryptSevLocateInitialSmramSaveStateMapPages (

+  OUT UINTN  *BaseAddress,

+  OUT UINTN  *NumberOfPages

+  )

+{

+  return RETURN_UNSUPPORTED;

+}

+

+/**

+  Returns the SEV encryption mask.

+

+  @return  The SEV pagtable encryption mask

+**/

+UINT64

+EFIAPI

+MemEncryptSevGetEncryptionMask (

+  VOID

+  )

+{

+  return 0;

+}

+

+/**

+  Returns a boolean to indicate whether DebugVirtualization is enabled.

+

+  @retval TRUE           DebugVirtualization is enabled

+  @retval FALSE          DebugVirtualization is not enabled

+**/

+BOOLEAN

+EFIAPI

+MemEncryptSevEsDebugVirtualizationIsEnabled (

+  VOID

+  )

+{

+  return FALSE;

+}

+

+/**

+  Returns the encryption state of the specified virtual address range.

+

+  @param[in]  Cr3BaseAddress          Cr3 Base Address (if zero then use

+                                      current CR3)

+  @param[in]  BaseAddress             Base address to check

+  @param[in]  Length                  Length of virtual address range

+

+  @retval MemEncryptSevAddressRangeUnencrypted  Address range is mapped

+                                                unencrypted

+  @retval MemEncryptSevAddressRangeEncrypted    Address range is mapped

+                                                encrypted

+  @retval MemEncryptSevAddressRangeMixed        Address range is mapped mixed

+  @retval MemEncryptSevAddressRangeError        Address range is not mapped

+**/

+MEM_ENCRYPT_SEV_ADDRESS_RANGE_STATE

+EFIAPI

+MemEncryptSevGetAddressRangeState (

+  IN PHYSICAL_ADDRESS  Cr3BaseAddress,

+  IN PHYSICAL_ADDRESS  BaseAddress,

+  IN UINTN             Length

+  )

+{

+  return MemEncryptSevAddressRangeUnencrypted;

+}

+

+/**

+  This function clears memory encryption bit for the MMIO region specified by

+  BaseAddress and NumPages.

+

+  @param[in]  Cr3BaseAddress          Cr3 Base Address (if zero then use

+                                      current CR3)

+  @param[in]  BaseAddress             The physical address that is the start

+                                      address of a MMIO region.

+  @param[in]  NumPages                The number of pages from start memory

+                                      region.

+

+  @retval RETURN_SUCCESS              The attributes were cleared for the

+                                      memory region.

+  @retval RETURN_INVALID_PARAMETER    Number of pages is zero.

+  @retval RETURN_UNSUPPORTED          Clearing the memory encryption attribute

+                                      is not supported

+**/

+RETURN_STATUS

+EFIAPI

+MemEncryptSevClearMmioPageEncMask (

+  IN PHYSICAL_ADDRESS  Cr3BaseAddress,

+  IN PHYSICAL_ADDRESS  BaseAddress,

+  IN UINTN             NumPages

+  )

+{

+  return RETURN_UNSUPPORTED;

+}

+

+/**

+  Pre-validate the system RAM when SEV-SNP is enabled in the guest VM.

+

+  @param[in]  BaseAddress             Base address

+  @param[in]  NumPages                Number of pages starting from the base address

+

+**/

+VOID

+EFIAPI

+MemEncryptSevSnpPreValidateSystemRam (

+  IN PHYSICAL_ADDRESS  BaseAddress,

+  IN UINTN             NumPages

+  )

+{

+  //

+  // Do nothing

+  //

+}

diff --git a/OvmfPkg/Library/MemEncryptSevLibNull/MemEncryptSevLibNull.inf b/OvmfPkg/Library/MemEncryptSevLibNull/MemEncryptSevLibNull.inf
new file mode 100644
index 0000000..a7ed263
--- /dev/null
+++ b/OvmfPkg/Library/MemEncryptSevLibNull/MemEncryptSevLibNull.inf
@@ -0,0 +1,32 @@
+## @file

+#  Library provides the helper functions for SEV guest

+#

+# Copyright (c) 2017 - 2024, Advanced Micro Devices. All rights reserved.<BR>

+# Copyright (c) Microsoft Corporation.

+#

+#  SPDX-License-Identifier: BSD-2-Clause-Patent

+#

+#

+##

+

+[Defines]

+  INF_VERSION                    = 1.25

+  BASE_NAME                      = MemEncryptSevLibNull

+  FILE_GUID                      = 02A5CD1B-05F2-4C7F-B8E9-66A5E66C47C7

+  MODULE_TYPE                    = BASE

+  VERSION_STRING                 = 1.0

+  LIBRARY_CLASS                  = MemEncryptSevLib

+

+#

+# The following information is for reference only and not required by the build

+# tools.

+#

+# VALID_ARCHITECTURES           = IA32 X64

+#

+

+[Packages]

+  MdePkg/MdePkg.dec

+  OvmfPkg/OvmfPkg.dec

+

+[Sources]

+  MemEncryptSevLibNull.c