MdeModulePkg/XhciPei: Fix Aligned Page Allocation

Add support for allocating aligned pages at an alignment higher
than 4K. The new function allocated memory taking into account
the padding required and then frees up unused pages before mapping
it.

Signed-off-by: Ashish Singhal <ashishsingha@nvidia.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>

MdeModulePkg/Bus/Pci/XhciPei/XhcPeim.h

@@ -349,4 +349,32 @@ IoMmuFreeBuffer (
   IN VOID                   *Mapping
   );
 
+/**
+  Allocates aligned pages that are suitable for an OperationBusMasterCommonBuffer or
+  OperationBusMasterCommonBuffer64 mapping.
+
+  @param  Pages                 The number of pages to allocate.
+  @param  Alignment             The requested alignment of the allocation.  Must be a power of two.
+  @param  HostAddress           A pointer to store the base system memory address of the
+                                allocated range.
+  @param  DeviceAddress         The resulting map address for the bus master PCI controller to use to
+                                access the hosts HostAddress.
+  @param  Mapping               A resulting value to pass to Unmap().
+
+  @retval EFI_SUCCESS           The requested memory pages were allocated.
+  @retval EFI_UNSUPPORTED       Attributes is unsupported. The only legal attribute bits are
+                                MEMORY_WRITE_COMBINE and MEMORY_CACHED.
+  @retval EFI_INVALID_PARAMETER One or more parameters are invalid.
+  @retval EFI_OUT_OF_RESOURCES  The memory pages could not be allocated.
+
+**/
+EFI_STATUS
+IoMmuAllocateAlignedBuffer (
+  IN UINTN                  Pages,
+  IN UINTN                  Alignment,
+  OUT VOID                  **HostAddress,
+  OUT EFI_PHYSICAL_ADDRESS  *DeviceAddress,
+  OUT VOID                  **Mapping
+  );
+
 #endif