OvmfPkg/PlatformInitLib: Add functions for EmuVariableNvStore

There are 3 functions added for EmuVariableNvStore:
 - PlatformReserveEmuVariableNvStore
 - PlatformInitEmuVariableNvStore
 - PlatformValidateNvVarStore

PlatformReserveEmuVariableNvStore allocate storage for NV variables early
on so it will be at a consistent address.

PlatformInitEmuVariableNvStore copies the content in
PcdOvmfFlashNvStorageVariableBase to the storage allocated by
PlatformReserveEmuVariableNvStore. This is used in the case that OVMF is
launched with -bios parameter. Because in that situation UEFI variables
will be partially emulated, and non-volatile variables may lose their
contents after a reboot. This makes the secure boot feature not working.

PlatformValidateNvVarStore is renamed from TdxValidateCfv and it is used
to validate the integrity of FlashNvVarStore
(PcdOvmfFlashNvStorageVariableBase). It should be called before
PlatformInitEmuVariableNvStore is called to copy over the content.

Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>

OvmfPkg/Include/Library/PlatformInitLib.h

@@ -234,4 +234,55 @@ PlatformTdxPublishRamRegions (
   VOID
   );
 
+/**
+  Check the integrity of NvVarStore.
+
+  @param[in] NvVarStoreBase - A pointer to NvVarStore header
+  @param[in] NvVarStoreSize - NvVarStore size
+
+  @retval  TRUE   - The NvVarStore is valid.
+  @retval  FALSE  - The NvVarStore is invalid.
+
+**/
+BOOLEAN
+EFIAPI
+PlatformValidateNvVarStore (
+  IN UINT8   *NvVarStoreBase,
+  IN UINT32  NvVarStoreSize
+  );
+
+/**
+ Allocate storage for NV variables early on so it will be
+ at a consistent address.  Since VM memory is preserved
+ across reboots, this allows the NV variable storage to survive
+ a VM reboot.
+
+ *
+ * @retval VOID* The pointer to the storage for NV Variables
+ */
+VOID *
+EFIAPI
+PlatformReserveEmuVariableNvStore (
+  VOID
+  );
+
+/**
+ When OVMF is lauched with -bios parameter, UEFI variables will be
+ partially emulated, and non-volatile variables may lose their contents
+ after a reboot. This makes the secure boot feature not working.
+
+ This function is used to initialize the EmuVariableNvStore
+ with the conent in PcdOvmfFlashNvStorageVariableBase.
+
+ @param[in] EmuVariableNvStore      - A pointer to EmuVariableNvStore
+
+ @retval  EFI_SUCCESS   - Successfully init the EmuVariableNvStore
+ @retval  Others        - As the error code indicates
+ */
+EFI_STATUS
+EFIAPI
+PlatformInitEmuVariableNvStore (
+  IN VOID  *EmuVariableNvStore
+  );
+
 #endif // PLATFORM_INIT_LIB_H_

OvmfPkg/Library/PlatformInitLib/Platform.c

@@ -25,10 +25,13 @@
 #include <IndustryStandard/Pci22.h>
 #include <IndustryStandard/Q35MchIch9.h>
 #include <IndustryStandard/QemuCpuHotplug.h>
+#include <Library/MemoryAllocationLib.h>
 #include <Library/QemuFwCfgLib.h>
 #include <Library/QemuFwCfgS3Lib.h>
 #include <Library/QemuFwCfgSimpleParserLib.h>
 #include <Library/PciLib.h>
+#include <Guid/SystemNvDataGuid.h>
+#include <Guid/VariableFormat.h>
 #include <OvmfPlatforms.h>
 
 #include <Library/PlatformInitLib.h>
@@ -576,3 +579,238 @@ PlatformMaxCpuCountInitialization (
   PlatformInfoHob->PcdCpuMaxLogicalProcessorNumber  = MaxCpuCount;
   PlatformInfoHob->PcdCpuBootLogicalProcessorNumber = BootCpuCount;
 }
+
+/**
+  Check padding data all bit should be 1.
+
+  @param[in] Buffer     - A pointer to buffer header
+  @param[in] BufferSize - Buffer size
+
+  @retval  TRUE   - The padding data is valid.
+  @retval  TRUE  - The padding data is invalid.
+
+**/
+BOOLEAN
+CheckPaddingData (
+  IN UINT8   *Buffer,
+  IN UINT32  BufferSize
+  )
+{
+  UINT32  index;
+
+  for (index = 0; index < BufferSize; index++) {
+    if (Buffer[index] != 0xFF) {
+      return FALSE;
+    }
+  }
+
+  return TRUE;
+}
+
+/**
+  Check the integrity of NvVarStore.
+
+  @param[in] NvVarStoreBase - A pointer to NvVarStore header
+  @param[in] NvVarStoreSize - NvVarStore size
+
+  @retval  TRUE   - The NvVarStore is valid.
+  @retval  FALSE  - The NvVarStore is invalid.
+
+**/
+BOOLEAN
+EFIAPI
+PlatformValidateNvVarStore (
+  IN UINT8   *NvVarStoreBase,
+  IN UINT32  NvVarStoreSize
+  )
+{
+  UINT16                         Checksum;
+  UINTN                          VariableBase;
+  UINT32                         VariableOffset;
+  UINT32                         VariableOffsetBeforeAlign;
+  EFI_FIRMWARE_VOLUME_HEADER     *NvVarStoreFvHeader;
+  VARIABLE_STORE_HEADER          *NvVarStoreHeader;
+  AUTHENTICATED_VARIABLE_HEADER  *VariableHeader;
+
+  static EFI_GUID  FvHdrGUID       = EFI_SYSTEM_NV_DATA_FV_GUID;
+  static EFI_GUID  VarStoreHdrGUID = EFI_AUTHENTICATED_VARIABLE_GUID;
+
+  VariableOffset = 0;
+
+  if (NvVarStoreBase == NULL) {
+    DEBUG ((DEBUG_ERROR, "NvVarStore pointer is NULL.\n"));
+    return FALSE;
+  }
+
+  //
+  // Verify the header zerovetor, filesystemguid,
+  // revision, signature, attributes, fvlength, checksum
+  // HeaderLength cannot be an odd number
+  //
+  NvVarStoreFvHeader = (EFI_FIRMWARE_VOLUME_HEADER *)NvVarStoreBase;
+
+  if ((!IsZeroBuffer (NvVarStoreFvHeader->ZeroVector, 16)) ||
+      (!CompareGuid (&FvHdrGUID, &NvVarStoreFvHeader->FileSystemGuid)) ||
+      (NvVarStoreFvHeader->Signature != EFI_FVH_SIGNATURE) ||
+      (NvVarStoreFvHeader->Attributes != 0x4feff) ||
+      (NvVarStoreFvHeader->Revision != EFI_FVH_REVISION) ||
+      (NvVarStoreFvHeader->FvLength != NvVarStoreSize)
+      )
+  {
+    DEBUG ((DEBUG_ERROR, "NvVarStore FV headers were invalid.\n"));
+    return FALSE;
+  }
+
+  //
+  // Verify the header checksum
+  //
+  Checksum = CalculateSum16 ((VOID *)NvVarStoreFvHeader, NvVarStoreFvHeader->HeaderLength);
+
+  if (Checksum != 0) {
+    DEBUG ((DEBUG_ERROR, "NvVarStore FV checksum was invalid.\n"));
+    return FALSE;
+  }
+
+  //
+  // Verify the header signature, size, format, state
+  //
+  NvVarStoreHeader = (VARIABLE_STORE_HEADER *)(NvVarStoreBase + NvVarStoreFvHeader->HeaderLength);
+  if ((!CompareGuid (&VarStoreHdrGUID, &NvVarStoreHeader->Signature)) ||
+      (NvVarStoreHeader->Format != VARIABLE_STORE_FORMATTED) ||
+      (NvVarStoreHeader->State != VARIABLE_STORE_HEALTHY) ||
+      (NvVarStoreHeader->Size > (NvVarStoreFvHeader->FvLength - NvVarStoreFvHeader->HeaderLength)) ||
+      (NvVarStoreHeader->Size < sizeof (VARIABLE_STORE_HEADER))
+      )
+  {
+    DEBUG ((DEBUG_ERROR, "NvVarStore header signature/size/format/state were invalid.\n"));
+    return FALSE;
+  }
+
+  //
+  // Verify the header startId, state
+  // Verify data to the end
+  //
+  VariableBase = (UINTN)NvVarStoreBase + NvVarStoreFvHeader->HeaderLength + sizeof (VARIABLE_STORE_HEADER);
+  while (VariableOffset  < (NvVarStoreHeader->Size - sizeof (VARIABLE_STORE_HEADER))) {
+    VariableHeader = (AUTHENTICATED_VARIABLE_HEADER *)(VariableBase + VariableOffset);
+    if (VariableHeader->StartId != VARIABLE_DATA) {
+      if (!CheckPaddingData ((UINT8 *)VariableHeader, NvVarStoreHeader->Size - sizeof (VARIABLE_STORE_HEADER) - VariableOffset)) {
+        DEBUG ((DEBUG_ERROR, "NvVarStore variable header StartId was invalid.\n"));
+        return FALSE;
+      }
+
+      VariableOffset = NvVarStoreHeader->Size - sizeof (VARIABLE_STORE_HEADER);
+    } else {
+      if (!((VariableHeader->State == VAR_IN_DELETED_TRANSITION) ||
+            (VariableHeader->State == VAR_DELETED) ||
+            (VariableHeader->State == VAR_HEADER_VALID_ONLY) ||
+            (VariableHeader->State == VAR_ADDED)))
+      {
+        DEBUG ((DEBUG_ERROR, "NvVarStore Variable header State was invalid.\n"));
+        return FALSE;
+      }
+
+      VariableOffset += sizeof (AUTHENTICATED_VARIABLE_HEADER) + VariableHeader->NameSize + VariableHeader->DataSize;
+      // Verify VariableOffset should be less than or equal NvVarStoreHeader->Size - sizeof(VARIABLE_STORE_HEADER)
+      if (VariableOffset > (NvVarStoreHeader->Size - sizeof (VARIABLE_STORE_HEADER))) {
+        DEBUG ((DEBUG_ERROR, "NvVarStore Variable header VariableOffset was invalid.\n"));
+        return FALSE;
+      }
+
+      VariableOffsetBeforeAlign = VariableOffset;
+      // 4 byte align
+      VariableOffset = (VariableOffset  + 3) & (UINTN)(~3);
+
+      if (!CheckPaddingData ((UINT8 *)(VariableBase + VariableOffsetBeforeAlign), VariableOffset - VariableOffsetBeforeAlign)) {
+        DEBUG ((DEBUG_ERROR, "NvVarStore Variable header PaddingData was invalid.\n"));
+        return FALSE;
+      }
+    }
+  }
+
+  return TRUE;
+}
+
+/**
+ Allocate storage for NV variables early on so it will be
+ at a consistent address.  Since VM memory is preserved
+ across reboots, this allows the NV variable storage to survive
+ a VM reboot.
+
+ *
+ * @retval VOID* The pointer to the storage for NV Variables
+ */
+VOID *
+EFIAPI
+PlatformReserveEmuVariableNvStore (
+  VOID
+  )
+{
+  VOID    *VariableStore;
+  UINT32  VarStoreSize;
+
+  VarStoreSize = 2 * PcdGet32 (PcdFlashNvStorageFtwSpareSize);
+  //
+  // Allocate storage for NV variables early on so it will be
+  // at a consistent address.  Since VM memory is preserved
+  // across reboots, this allows the NV variable storage to survive
+  // a VM reboot.
+  //
+  VariableStore =
+    AllocateRuntimePages (
+      EFI_SIZE_TO_PAGES (VarStoreSize)
+      );
+  DEBUG ((
+    DEBUG_INFO,
+    "Reserved variable store memory: 0x%p; size: %dkb\n",
+    VariableStore,
+    VarStoreSize / 1024
+    ));
+
+  return VariableStore;
+}
+
+/**
+ When OVMF is lauched with -bios parameter, UEFI variables will be
+ partially emulated, and non-volatile variables may lose their contents
+ after a reboot. This makes the secure boot feature not working.
+
+ This function is used to initialize the EmuVariableNvStore
+ with the conent in PcdOvmfFlashNvStorageVariableBase.
+
+ @param[in] EmuVariableNvStore      - A pointer to EmuVariableNvStore
+
+ @retval  EFI_SUCCESS   - Successfully init the EmuVariableNvStore
+ @retval  Others        - As the error code indicates
+ */
+EFI_STATUS
+EFIAPI
+PlatformInitEmuVariableNvStore (
+  IN VOID  *EmuVariableNvStore
+  )
+{
+  UINT8   *Base;
+  UINT32  Size;
+  UINT32  EmuVariableNvStoreSize;
+
+  EmuVariableNvStoreSize = 2 * PcdGet32 (PcdFlashNvStorageFtwSpareSize);
+  if ((EmuVariableNvStore == NULL) || (EmuVariableNvStoreSize == 0)) {
+    DEBUG ((DEBUG_ERROR, "Invalid EmuVariableNvStore parameter.\n"));
+    return EFI_INVALID_PARAMETER;
+  }
+
+  Base = (UINT8 *)(UINTN)PcdGet32 (PcdOvmfFlashNvStorageVariableBase);
+  Size = (UINT32)PcdGet32 (PcdFlashNvStorageVariableSize);
+  ASSERT (Size < EmuVariableNvStoreSize);
+
+  if (!PlatformValidateNvVarStore (Base, PcdGet32 (PcdCfvRawDataSize))) {
+    ASSERT (FALSE);
+    return EFI_INVALID_PARAMETER;
+  }
+
+  DEBUG ((DEBUG_INFO, "Init EmuVariableNvStore with the content in FlashNvStorage\n"));
+
+  CopyMem (EmuVariableNvStore, Base, Size);
+
+  return EFI_SUCCESS;
+}

OvmfPkg/Library/PlatformInitLib/PlatformInitLib.inf

@@ -47,6 +47,7 @@
   HobLib
   QemuFwCfgLib
   QemuFwCfgSimpleParserLib
+  MemoryAllocationLib
   MtrrLib
   PcdLib
   PciLib
@@ -96,6 +97,8 @@
   gUefiOvmfPkgTokenSpaceGuid.PcdGuidedExtractHandlerTableSize
 
   gUefiOvmfPkgTokenSpaceGuid.PcdTdxAcceptPageSize
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFlashNvStorageVariableBase
+  gUefiOvmfPkgTokenSpaceGuid.PcdCfvRawDataSize
 
 [FeaturePcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdDxeIplSwitchToLongMode