OvmfPkg/Library/XenPlatformLib: New library

The purpose of XenPlatformLib is to regroup the few functions that are
used in several places to detect if Xen is detected, and to get the
XenInfo HOB.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1689
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20190813113119.14804-14-anthony.perard@citrix.com>

OvmfPkg/Include/Library/XenPlatformLib.h

@@ -0,0 +1,53 @@
+/** @file
+  Get information about Xen
+
+  This library simply allow to find out if OVMF is running under Xen and
+  allow to get more information when it is the case.
+
+  Copyright (c) 2019, Citrix Systems, Inc.
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef _XEN_PLATFORM_LIB_H_
+#define _XEN_PLATFORM_LIB_H_
+
+#include <Guid/XenInfo.h>
+
+/**
+  This function detects if OVMF is running on Xen.
+
+  @retval TRUE    OVMF is running on Xen
+  @retval FALSE   Xen has not been detected
+**/
+BOOLEAN
+EFIAPI
+XenDetected (
+  VOID
+  );
+
+/**
+  This function detect if OVMF have started via the PVH entry point.
+
+  @retval TRUE  PVH entry point as been used
+  @retval FALSE OVMF have started via the HVM route
+**/
+BOOLEAN
+EFIAPI
+XenPvhDetected (
+  VOID
+  );
+
+/**
+  This function return a pointer to the XenInfo HOB.
+
+  @return  XenInfo pointer or NULL if not available
+**/
+EFI_XEN_INFO *
+EFIAPI
+XenGetInfoHOB (
+  VOID
+  );
+
+#endif