OvmfPkg/Library/XenPlatformLib/XenPlatformLib.c

   1 /** @file
   2   Get information about Xen
   3
   4   This library simply allow to find out if OVMF is running under Xen and
   5   allow to get more information when it is the case.
   6
   7   Copyright (c) 2019, Citrix Systems, Inc.
   8
   9   SPDX-License-Identifier: BSD-2-Clause-Patent
  10
  11 **/
  12
  13 #include <PiDxe.h>
  14 #include <Library/HobLib.h>
  15 #include <Library/XenPlatformLib.h>
  16
  17 /**
  18   This function return a pointer to the XenInfo HOB.
  19
  20   @return  XenInfo pointer or NULL if not available
  21 **/
  22 EFI_XEN_INFO *
  23 EFIAPI
  24 XenGetInfoHOB (
  25   VOID
  26   )
  27 {
  28   EFI_HOB_GUID_TYPE    *GuidHob;
  29   STATIC BOOLEAN       Cached = FALSE;
  30   STATIC EFI_XEN_INFO  *XenInfo;
  31
  32   //
  33   // Return the cached result for the benefit of XenDetected that can be
  34   // called many times.
  35   //
  36   if (Cached) {
  37     return XenInfo;
  38   }
  39
  40   GuidHob = GetFirstGuidHob (&gEfiXenInfoGuid);
  41   if (GuidHob == NULL) {
  42     XenInfo = NULL;
  43   } else {
  44     XenInfo = (EFI_XEN_INFO *)GET_GUID_HOB_DATA (GuidHob);
  45   }
  46
  47   Cached = TRUE;
  48   return XenInfo;
  49 }
  50
  51 /**
  52   This function detects if OVMF is running on Xen.
  53
  54   @retval TRUE    OVMF is running on Xen
  55   @retval FALSE   Xen has not been detected
  56 **/
  57 BOOLEAN
  58 EFIAPI
  59 XenDetected (
  60   VOID
  61   )
  62 {
  63   return (XenGetInfoHOB () != NULL);
  64 }
  65
  66 /**
  67   This function detect if OVMF have started via the PVH entry point.
  68
  69   @retval TRUE  PVH entry point as been used
  70   @retval FALSE OVMF have started via the HVM route
  71 **/
  72 BOOLEAN
  73 EFIAPI
  74 XenPvhDetected (
  75   VOID
  76   )
  77 {
  78   EFI_XEN_INFO  *XenInfo;
  79
  80   XenInfo = XenGetInfoHOB ();
  81   return (XenInfo != NULL && XenInfo->RsdpPvh != NULL);
  82 }