OvmfPkg: XenHypercallLib: introduce XenHypercallIsAvailable()

[mirror_edk2.git] / OvmfPkg / Library / XenHypercallLib / X86XenHypercall.c

/** @file\r
  Xen Hypercall Library implementation for Intel architecture\r
\r
Copyright (c) 2014, Linaro Ltd. All rights reserved.<BR>\r
This program and the accompanying materials are licensed and made available under\r
the terms and conditions of the BSD License that accompanies this distribution.\r
The full text of the license may be found at\r
http://opensource.org/licenses/bsd-license.php.\r
\r
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
\r
**/\r
\r
#include <PiDxe.h>\r
#include <Library/HobLib.h>\r
#include <Library/DebugLib.h>\r
#include <Guid/XenInfo.h>\r
\r
STATIC VOID    *HyperPage;\r
\r
/**\r
  Check if the Xen Hypercall library is able to make calls to the Xen\r
  hypervisor.\r
\r
  Client code should call further functions in this library only if, and after,\r
  this function returns TRUE.\r
\r
  @retval TRUE   Hypercalls are available.\r
  @retval FALSE  Hypercalls are not available.\r
**/\r
BOOLEAN\r
EFIAPI\r
XenHypercallIsAvailable (\r
  VOID\r
  )\r
{\r
  return HyperPage != NULL;\r
}\r
\r
//\r
// Interface exposed by the ASM implementation of the core hypercall\r
//\r
INTN\r
EFIAPI\r
__XenHypercall2 (\r
  IN     VOID *HypercallAddr,\r
  IN OUT INTN Arg1,\r
  IN OUT INTN Arg2\r
  );\r
\r
/**\r
  Library constructor: retrieves the Hyperpage address\r
  from the gEfiXenInfoGuid HOB\r
**/\r
\r
RETURN_STATUS\r
EFIAPI\r
XenHypercallLibInit (\r
  VOID\r
  )\r
{\r
  EFI_HOB_GUID_TYPE   *GuidHob;\r
  EFI_XEN_INFO        *XenInfo;\r
\r
  GuidHob = GetFirstGuidHob (&gEfiXenInfoGuid);\r
  if (GuidHob == NULL) {\r
    return RETURN_NOT_FOUND;\r
  }\r
  XenInfo = (EFI_XEN_INFO *) GET_GUID_HOB_DATA (GuidHob);\r
  HyperPage = XenInfo->HyperPages;\r
  return RETURN_SUCCESS;\r
}\r
\r
/**\r
  This function will put the two arguments in the right place (registers) and\r
  invoke the hypercall identified by HypercallID.\r
\r
  @param HypercallID    The symbolic ID of the hypercall to be invoked\r
  @param Arg1           First argument.\r
  @param Arg2           Second argument.\r
\r
  @return   Return 0 if success otherwise it return an errno.\r
**/\r
INTN\r
EFIAPI\r
XenHypercall2 (\r
  IN     UINTN  HypercallID,\r
  IN OUT INTN   Arg1,\r
  IN OUT INTN   Arg2\r
  )\r
{\r
  ASSERT (HyperPage != NULL);\r
\r
  return __XenHypercall2 ((UINT8*)HyperPage + HypercallID * 32, Arg1, Arg2);\r
}\r