+\r
+/**\r
+ This function clears memory encryption bit for the MMIO region specified by\r
+ BaseAddress and NumPages.\r
+\r
+ @param[in] Cr3BaseAddress Cr3 Base Address (if zero then use\r
+ current CR3)\r
+ @param[in] BaseAddress The physical address that is the start\r
+ address of a MMIO region.\r
+ @param[in] NumPages The number of pages from start memory\r
+ region.\r
+\r
+ @retval RETURN_SUCCESS The attributes were cleared for the\r
+ memory region.\r
+ @retval RETURN_INVALID_PARAMETER Number of pages is zero.\r
+ @retval RETURN_UNSUPPORTED Clearing the memory encryption attribute\r
+ is not supported\r
+**/\r
+RETURN_STATUS\r
+EFIAPI\r
+MemEncryptSevClearMmioPageEncMask (\r
+ IN PHYSICAL_ADDRESS Cr3BaseAddress,\r
+ IN PHYSICAL_ADDRESS BaseAddress,\r
+ IN UINTN NumPages\r
+ )\r
+{\r
+ //\r
+ // Memory encryption bit is not accessible in 32-bit mode\r
+ //\r
+ return RETURN_UNSUPPORTED;\r
+}\r