OvmfPkg/QemuFwCfgLib: Prepare for SEV support

Add SEV specific internal functions which will be used while intergrating
the SEV support into QemuFwCfgLib.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLibInternal.h

@@ -2,6 +2,7 @@
   Internal interfaces specific to the QemuFwCfgLib instances in OvmfPkg.
 
   Copyright (C) 2016, Red Hat, Inc.
+  Copyright (C) 2017, Advanced Micro Devices. All rights reserved
 
   This program and the accompanying materials are licensed and made available
   under the terms and conditions of the BSD License which accompanies this
@@ -43,4 +44,40 @@ InternalQemuFwCfgDmaIsAvailable (
   VOID
   );
 
+/**
+ Returns a boolean indicating whether SEV support is enabled
+
+ @retval    TRUE    SEV is enabled
+ @retval    FALSE   SEV is disabled
+**/
+BOOLEAN
+InternalQemuFwCfgSevIsEnabled (
+  VOID
+  );
+
+/**
+ Allocate a bounce buffer for SEV DMA.
+
+  @param[out]    Buffer   Allocated DMA Buffer pointer
+  @param[in]     NumPage  Number of pages.
+
+**/
+VOID
+InternalQemuFwCfgSevDmaAllocateBuffer (
+  OUT    VOID     **Buffer,
+  IN     UINT32   NumPages
+  );
+
+/**
+ Free the DMA buffer allocated using InternalQemuFwCfgSevDmaAllocateBuffer
+
+  @param[in]     NumPage  Number of pages.
+  @param[in]     Buffer   DMA Buffer pointer
+
+**/
+VOID
+InternalQemuFwCfgSevDmaFreeBuffer (
+  IN     VOID     *Buffer,
+  IN     UINT32   NumPages
+  );
 #endif