OvmfPkg: introduce XenMemMapInitialization

This function parses E820 map provided by Xen and arrange memory maps
accordingly.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
[jordan.l.justen@intel.com: XenGetE820Map: VS2010 compat; add assert]
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14945 6f19259b-4bc3-4df7-8a09-765794883524

OvmfPkg/PlatformPei/Xen.c

@@ -1,7 +1,7 @@
 /**@file
   Xen Platform PEI support
 
-  Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2006 - 2013, Intel Corporation. All rights reserved.<BR>
   Copyright (c) 2011, Andrei Warkentin <andreiw@motorola.com>
 
   This program and the accompanying materials
@@ -29,9 +29,37 @@
 #include <Guid/XenInfo.h>
 
 #include "Platform.h"
+#include "Xen.h"
 
 EFI_XEN_INFO mXenInfo;
 
+/**
+  Returns E820 map provided by Xen
+
+  @param Entries      Pointer to E820 map
+  @param Count        Number of entries
+
+  @return EFI_STATUS
+**/
+EFI_STATUS
+XenGetE820Map (
+  EFI_E820_ENTRY64 **Entries,
+  UINT32 *Count
+  )
+{
+  EFI_XEN_OVMF_INFO *Info =
+    (EFI_XEN_OVMF_INFO *)(UINTN) OVMF_INFO_PHYSICAL_ADDRESS;
+
+  if (AsciiStrCmp ((CHAR8 *) Info->Signature, "XenHVMOVMF")) {
+    return EFI_NOT_FOUND;
+  }
+
+  ASSERT (Info->E820 < MAX_ADDRESS);
+  *Entries = (EFI_E820_ENTRY64 *)(UINTN) Info->E820;
+  *Count = Info->E820EntriesCount;
+
+  return EFI_SUCCESS;
+}
 
 /**
   Connects to the Hypervisor.