1/** @file
2  Xen Hypercall Library implementation for Intel architecture
3
4Copyright (c) 2014, Linaro Ltd. All rights reserved.<BR>
5This program and the accompanying materials are licensed and made available under
6the terms and conditions of the BSD License that accompanies this distribution.
7The full text of the license may be found at
8http://opensource.org/licenses/bsd-license.php.
9
10THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
11WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
12
13**/
14
15#include <PiDxe.h>
16#include <Library/HobLib.h>
17#include <Library/DebugLib.h>
18#include <Guid/XenInfo.h>
19
20STATIC VOID    *HyperPage;
21
22/**
23  Check if the Xen Hypercall library is able to make calls to the Xen
24  hypervisor.
25
26  Client code should call further functions in this library only if, and after,
27  this function returns TRUE.
28
29  @retval TRUE   Hypercalls are available.
30  @retval FALSE  Hypercalls are not available.
31**/
32BOOLEAN
33EFIAPI
34XenHypercallIsAvailable (
35  VOID
36  )
37{
38  return HyperPage != NULL;
39}
40
41//
42// Interface exposed by the ASM implementation of the core hypercall
43//
44INTN
45EFIAPI
46__XenHypercall2 (
47  IN     VOID *HypercallAddr,
48  IN OUT INTN Arg1,
49  IN OUT INTN Arg2
50  );
51
52/**
53  Library constructor: retrieves the Hyperpage address
54  from the gEfiXenInfoGuid HOB
55**/
56
57RETURN_STATUS
58EFIAPI
59XenHypercallLibInit (
60  VOID
61  )
62{
63  EFI_HOB_GUID_TYPE   *GuidHob;
64  EFI_XEN_INFO        *XenInfo;
65
66  GuidHob = GetFirstGuidHob (&gEfiXenInfoGuid);
67  if (GuidHob == NULL) {
68    //
69    // We don't fail library construction, since that has catastrophic
70    // consequences for client modules (whereas those modules may easily be
71    // running on a non-Xen platform). Instead, XenHypercallIsAvailable() above
72    // will return FALSE.
73    //
74    return RETURN_SUCCESS;
75  }
76  XenInfo = (EFI_XEN_INFO *) GET_GUID_HOB_DATA (GuidHob);
77  HyperPage = XenInfo->HyperPages;
78  return RETURN_SUCCESS;
79}
80
81/**
82  This function will put the two arguments in the right place (registers) and
83  invoke the hypercall identified by HypercallID.
84
85  @param HypercallID    The symbolic ID of the hypercall to be invoked
86  @param Arg1           First argument.
87  @param Arg2           Second argument.
88
89  @return   Return 0 if success otherwise it return an errno.
90**/
91INTN
92EFIAPI
93XenHypercall2 (
94  IN     UINTN  HypercallID,
95  IN OUT INTN   Arg1,
96  IN OUT INTN   Arg2
97  )
98{
99  ASSERT (HyperPage != NULL);
100
101  return __XenHypercall2 ((UINT8*)HyperPage + HypercallID * 32, Arg1, Arg2);
102}
103