OvmfPkg/Library/XenHypercallLib/X86XenHypercall.c

   1 /** @file
   2   Xen Hypercall Library implementation for Intel architecture
   3
   4 Copyright (c) 2014, Linaro Ltd. All rights reserved.<BR>
   5 SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include <PiDxe.h>
  10 #include <Library/HobLib.h>
  11 #include <Library/DebugLib.h>
  12 #include <Guid/XenInfo.h>
  13
  14 STATIC VOID  *HyperPage;
  15
  16 /**
  17   Check if the Xen Hypercall library is able to make calls to the Xen
  18   hypervisor.
  19
  20   Client code should call further functions in this library only if, and after,
  21   this function returns TRUE.
  22
  23   @retval TRUE   Hypercalls are available.
  24   @retval FALSE  Hypercalls are not available.
  25 **/
  26 BOOLEAN
  27 EFIAPI
  28 XenHypercallIsAvailable (
  29   VOID
  30   )
  31 {
  32   return HyperPage != NULL;
  33 }
  34
  35 //
  36 // Interface exposed by the ASM implementation of the core hypercall
  37 //
  38 INTN
  39 EFIAPI
  40 __XenHypercall2 (
  41   IN     VOID  *HypercallAddr,
  42   IN OUT INTN  Arg1,
  43   IN OUT INTN  Arg2
  44   );
  45
  46 /**
  47   Library constructor: retrieves the Hyperpage address
  48   from the gEfiXenInfoGuid HOB
  49 **/
  50 RETURN_STATUS
  51 EFIAPI
  52 XenHypercallLibInit (
  53   VOID
  54   )
  55 {
  56   EFI_HOB_GUID_TYPE  *GuidHob;
  57   EFI_XEN_INFO       *XenInfo;
  58
  59   GuidHob = GetFirstGuidHob (&gEfiXenInfoGuid);
  60   if (GuidHob == NULL) {
  61     return RETURN_NOT_FOUND;
  62   }
  63
  64   XenInfo   = (EFI_XEN_INFO *)GET_GUID_HOB_DATA (GuidHob);
  65   HyperPage = XenInfo->HyperPages;
  66   return RETURN_SUCCESS;
  67 }
  68
  69 /**
  70   This function will put the two arguments in the right place (registers) and
  71   invoke the hypercall identified by HypercallID.
  72
  73   @param HypercallID    The symbolic ID of the hypercall to be invoked
  74   @param Arg1           First argument.
  75   @param Arg2           Second argument.
  76
  77   @return   Return 0 if success otherwise it return an errno.
  78 **/
  79 INTN
  80 EFIAPI
  81 XenHypercall2 (
  82   IN     UINTN  HypercallID,
  83   IN OUT INTN   Arg1,
  84   IN OUT INTN   Arg2
  85   )
  86 {
  87   ASSERT (HyperPage != NULL);
  88
  89   return __XenHypercall2 ((UINT8 *)HyperPage + HypercallID * 32, Arg1, Arg2);
  90 }