1 files changed, 153 insertions, 0 deletions
diff --git a/src/VBox/Devices/EFI/Firmware/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeCache.c b/src/VBox/Devices/EFI/Firmware/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeCache.c
new file mode 100644
index 00000000..131aae3f
--- /dev/null
+++ b/src/VBox/Devices/EFI/Firmware/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeCache.c
@@ -0,0 +1,153 @@
+/** @file
+  Functions related to managing the UEFI variable runtime cache. This file should only include functions
+  used by the SMM UEFI variable driver.
+
+  Caution: This module requires additional review when modified.
+  This driver will have external input - variable data. They may be input in SMM mode.
+  This external input must be validated carefully to avoid security issue like
+  buffer overflow, integer overflow.
+
+Copyright (c) 2019, Intel Corporation. All rights reserved.<BR>
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include "VariableParsing.h"
+#include "VariableRuntimeCache.h"
+
+extern VARIABLE_MODULE_GLOBAL   *mVariableModuleGlobal;
+extern VARIABLE_STORE_HEADER    *mNvVariableCache;
+
+/**
+  Copies any pending updates to runtime variable caches.
+
+  @retval EFI_UNSUPPORTED         The volatile store to be updated is not initialized properly.
+  @retval EFI_SUCCESS             The volatile store was updated successfully.
+
+**/
+EFI_STATUS
+FlushPendingRuntimeVariableCacheUpdates (
+  VOID
+  )
+{
+  VARIABLE_RUNTIME_CACHE_CONTEXT    *VariableRuntimeCacheContext;
+
+  VariableRuntimeCacheContext = &mVariableModuleGlobal->VariableGlobal.VariableRuntimeCacheContext;
+
+  if (VariableRuntimeCacheContext->VariableRuntimeNvCache.Store == NULL ||
+      VariableRuntimeCacheContext->VariableRuntimeVolatileCache.Store == NULL ||
+      VariableRuntimeCacheContext->PendingUpdate == NULL) {
+    return EFI_UNSUPPORTED;
+  }
+
+  if (*(VariableRuntimeCacheContext->PendingUpdate)) {
+    if (VariableRuntimeCacheContext->VariableRuntimeHobCache.Store != NULL &&
+        mVariableModuleGlobal->VariableGlobal.HobVariableBase > 0) {
+      CopyMem (
+        (VOID *) (
+          ((UINT8 *) (UINTN) VariableRuntimeCacheContext->VariableRuntimeHobCache.Store) +
+          VariableRuntimeCacheContext->VariableRuntimeHobCache.PendingUpdateOffset
+          ),
+        (VOID *) (
+          ((UINT8 *) (UINTN) mVariableModuleGlobal->VariableGlobal.HobVariableBase) +
+          VariableRuntimeCacheContext->VariableRuntimeHobCache.PendingUpdateOffset
+          ),
+        VariableRuntimeCacheContext->VariableRuntimeHobCache.PendingUpdateLength
+        );
+      VariableRuntimeCacheContext->VariableRuntimeHobCache.PendingUpdateLength = 0;
+      VariableRuntimeCacheContext->VariableRuntimeHobCache.PendingUpdateOffset = 0;
+    }
+
+    CopyMem (
+      (VOID *) (
+        ((UINT8 *) (UINTN) VariableRuntimeCacheContext->VariableRuntimeNvCache.Store) +
+        VariableRuntimeCacheContext->VariableRuntimeNvCache.PendingUpdateOffset
+        ),
+      (VOID *) (
+        ((UINT8 *) (UINTN) mNvVariableCache) +
+        VariableRuntimeCacheContext->VariableRuntimeNvCache.PendingUpdateOffset
+        ),
+      VariableRuntimeCacheContext->VariableRuntimeNvCache.PendingUpdateLength
+      );
+    VariableRuntimeCacheContext->VariableRuntimeNvCache.PendingUpdateLength = 0;
+    VariableRuntimeCacheContext->VariableRuntimeNvCache.PendingUpdateOffset = 0;
+
+    CopyMem (
+      (VOID *) (
+        ((UINT8 *) (UINTN) VariableRuntimeCacheContext->VariableRuntimeVolatileCache.Store) +
+        VariableRuntimeCacheContext->VariableRuntimeVolatileCache.PendingUpdateOffset
+      ),
+      (VOID *) (
+        ((UINT8 *) (UINTN) mVariableModuleGlobal->VariableGlobal.VolatileVariableBase) +
+        VariableRuntimeCacheContext->VariableRuntimeVolatileCache.PendingUpdateOffset
+        ),
+      VariableRuntimeCacheContext->VariableRuntimeVolatileCache.PendingUpdateLength
+      );
+    VariableRuntimeCacheContext->VariableRuntimeVolatileCache.PendingUpdateLength = 0;
+    VariableRuntimeCacheContext->VariableRuntimeVolatileCache.PendingUpdateOffset = 0;
+    *(VariableRuntimeCacheContext->PendingUpdate) = FALSE;
+  }
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Synchronizes the runtime variable caches with all pending updates outside runtime.
+
+  Ensures all conditions are met to maintain coherency for runtime cache updates. This function will attempt
+  to write the given update (and any other pending updates) if the ReadLock is available. Otherwise, the
+  update is added as a pending update for the given variable store and it will be flushed to the runtime cache
+  at the next opportunity the ReadLock is available.
+
+  @param[in] VariableRuntimeCache Variable runtime cache structure for the runtime cache being synchronized.
+  @param[in] Offset               Offset in bytes to apply the update.
+  @param[in] Length               Length of data in bytes of the update.
+
+  @retval EFI_SUCCESS             The update was added as a pending update successfully. If the variable runtime
+                                  cache ReadLock was available, the runtime cache was updated successfully.
+  @retval EFI_UNSUPPORTED         The volatile store to be updated is not initialized properly.
+
+**/
+EFI_STATUS
+SynchronizeRuntimeVariableCache (
+  IN  VARIABLE_RUNTIME_CACHE          *VariableRuntimeCache,
+  IN  UINTN                           Offset,
+  IN  UINTN                           Length
+  )
+{
+  if (VariableRuntimeCache == NULL) {
+    return EFI_INVALID_PARAMETER;
+  } else if (VariableRuntimeCache->Store == NULL) {
+    // The runtime cache may not be active or allocated yet.
+    // In either case, return EFI_SUCCESS instead of EFI_NOT_AVAILABLE_YET.
+    return EFI_SUCCESS;
+  }
+
+  if (mVariableModuleGlobal->VariableGlobal.VariableRuntimeCacheContext.PendingUpdate == NULL ||
+      mVariableModuleGlobal->VariableGlobal.VariableRuntimeCacheContext.ReadLock == NULL) {
+    return EFI_UNSUPPORTED;
+  }
+
+  if (*(mVariableModuleGlobal->VariableGlobal.VariableRuntimeCacheContext.PendingUpdate) &&
+      VariableRuntimeCache->PendingUpdateLength > 0) {
+    VariableRuntimeCache->PendingUpdateLength =
+      (UINT32) (
+        MAX (
+          (UINTN) (VariableRuntimeCache->PendingUpdateOffset + VariableRuntimeCache->PendingUpdateLength),
+          Offset + Length
+        ) - MIN ((UINTN) VariableRuntimeCache->PendingUpdateOffset, Offset)
+      );
+    VariableRuntimeCache->PendingUpdateOffset =
+      (UINT32) MIN ((UINTN) VariableRuntimeCache->PendingUpdateOffset, Offset);
+  } else {
+    VariableRuntimeCache->PendingUpdateLength = (UINT32) Length;
+    VariableRuntimeCache->PendingUpdateOffset = (UINT32) Offset;
+  }
+  *(mVariableModuleGlobal->VariableGlobal.VariableRuntimeCacheContext.PendingUpdate) = TRUE;
+
+  if (*(mVariableModuleGlobal->VariableGlobal.VariableRuntimeCacheContext.ReadLock) == FALSE) {
+    return FlushPendingRuntimeVariableCacheUpdates ();
+  }
+
+  return EFI_SUCCESS;
+}