summaryrefslogtreecommitdiffstats
path: root/OvmfPkg/XenBusDxe/GrantTable.c
blob: 76e0e8f17f0b4f9ed84402a3c52432dedb8ddbd5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
/** @file
  Grant Table function implementation.

  Grant Table are used to grant access to certain page of the current
  VM to an other VM.

  Author: Steven Smith (sos22@cam.ac.uk)
  Changes: Grzegorz Milos (gm281@cam.ac.uk)
  Copyright (C) 2006, Cambridge University
  Copyright (C) 2014, Citrix Ltd.

  SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include "XenBusDxe.h"

#include <IndustryStandard/Xen/memory.h>

#include <Library/XenHypercallLib.h>
#include <Library/SynchronizationLib.h>

#include "GrantTable.h"

#define NR_RESERVED_ENTRIES  8

#define NR_GRANT_FRAMES   (FixedPcdGet32 (PcdXenGrantFrames))
#define NR_GRANT_ENTRIES  (NR_GRANT_FRAMES * EFI_PAGE_SIZE / sizeof(grant_entry_v1_t))

STATIC grant_entry_v1_t  *GrantTable = NULL;
STATIC grant_ref_t       GrantList[NR_GRANT_ENTRIES];
STATIC EFI_LOCK          mGrantListLock;
#ifdef GNT_DEBUG
STATIC BOOLEAN  GrantInUseList[NR_GRANT_ENTRIES];
#endif

STATIC
VOID
XenGrantTablePutFreeEntry (
  grant_ref_t  Ref
  )
{
  EfiAcquireLock (&mGrantListLock);
 #ifdef GNT_DEBUG
  ASSERT (GrantInUseList[Ref]);
  GrantInUseList[Ref] = FALSE;
 #endif
  GrantList[Ref] = GrantList[0];
  GrantList[0]   = Ref;
  EfiReleaseLock (&mGrantListLock);
}

STATIC
grant_ref_t
XenGrantTableGetFreeEntry (
  VOID
  )
{
  grant_ref_t  Ref;

  EfiAcquireLock (&mGrantListLock);
  Ref = GrantList[0];
  ASSERT (Ref >= NR_RESERVED_ENTRIES && Ref < NR_GRANT_ENTRIES);
  GrantList[0] = GrantList[Ref];
 #ifdef GNT_DEBUG
  ASSERT (!GrantInUseList[Ref]);
  GrantInUseList[Ref] = TRUE;
 #endif
  EfiReleaseLock (&mGrantListLock);
  return Ref;
}

STATIC
grant_ref_t
XenGrantTableGrantAccess (
  IN domid_t  DomainId,
  IN UINTN    Frame,
  IN BOOLEAN  ReadOnly
  )
{
  grant_ref_t  Ref;
  UINT16       Flags;

  ASSERT (GrantTable != NULL);
  Ref                   = XenGrantTableGetFreeEntry ();
  GrantTable[Ref].frame = (UINT32)Frame;
  GrantTable[Ref].domid = DomainId;
  MemoryFence ();
  Flags = GTF_permit_access;
  if (ReadOnly) {
    Flags |= GTF_readonly;
  }

  GrantTable[Ref].flags = Flags;

  return Ref;
}

STATIC
EFI_STATUS
XenGrantTableEndAccess (
  grant_ref_t  Ref
  )
{
  UINT16  Flags, OldFlags;

  ASSERT (GrantTable != NULL);
  ASSERT (Ref >= NR_RESERVED_ENTRIES && Ref < NR_GRANT_ENTRIES);

  OldFlags = GrantTable[Ref].flags;
  do {
    if ((Flags = OldFlags) & (GTF_reading | GTF_writing)) {
      DEBUG ((DEBUG_WARN, "WARNING: g.e. still in use! (%x)\n", Flags));
      return EFI_NOT_READY;
    }

    OldFlags = InterlockedCompareExchange16 (&GrantTable[Ref].flags, Flags, 0);
  } while (OldFlags != Flags);

  XenGrantTablePutFreeEntry (Ref);
  return EFI_SUCCESS;
}

VOID
XenGrantTableInit (
  IN XENBUS_DEVICE  *Dev
  )
{
  xen_add_to_physmap_t  Parameters;
  INTN                  Index;
  INTN                  ReturnCode;

 #ifdef GNT_DEBUG
  SetMem (GrantInUseList, sizeof (GrantInUseList), 1);
 #endif
  EfiInitializeLock (&mGrantListLock, TPL_NOTIFY);
  for (Index = NR_RESERVED_ENTRIES; Index < NR_GRANT_ENTRIES; Index++) {
    XenGrantTablePutFreeEntry ((grant_ref_t)Index);
  }

  GrantTable = (VOID *)(UINTN)Dev->XenIo->GrantTableAddress;
  for (Index = 0; Index < NR_GRANT_FRAMES; Index++) {
    Parameters.domid = DOMID_SELF;
    Parameters.idx   = Index;
    Parameters.space = XENMAPSPACE_grant_table;
    Parameters.gpfn  = (xen_pfn_t)((UINTN)GrantTable >> EFI_PAGE_SHIFT) + Index;
    ReturnCode       = XenHypercallMemoryOp (XENMEM_add_to_physmap, &Parameters);
    if (ReturnCode != 0) {
      DEBUG ((
        DEBUG_ERROR,
        "Xen GrantTable, add_to_physmap hypercall error: %Ld\n",
        (INT64)ReturnCode
        ));
    }
  }
}

VOID
XenGrantTableDeinit (
  XENBUS_DEVICE  *Dev
  )
{
  INTN                       ReturnCode, Index;
  xen_remove_from_physmap_t  Parameters;

  if (GrantTable == NULL) {
    return;
  }

  for (Index = NR_GRANT_FRAMES - 1; Index >= 0; Index--) {
    Parameters.domid = DOMID_SELF;
    Parameters.gpfn  = (xen_pfn_t)((UINTN)GrantTable >> EFI_PAGE_SHIFT) + Index;
    DEBUG ((
      DEBUG_INFO,
      "Xen GrantTable, removing %Lx\n",
      (UINT64)Parameters.gpfn
      ));
    ReturnCode = XenHypercallMemoryOp (XENMEM_remove_from_physmap, &Parameters);
    if (ReturnCode != 0) {
      DEBUG ((
        DEBUG_ERROR,
        "Xen GrantTable, remove_from_physmap hypercall error: %Ld\n",
        (INT64)ReturnCode
        ));
    }
  }

  GrantTable = NULL;
}

EFI_STATUS
EFIAPI
XenBusGrantAccess (
  IN  XENBUS_PROTOCOL  *This,
  IN  domid_t          DomainId,
  IN  UINTN            Frame, // MFN
  IN  BOOLEAN          ReadOnly,
  OUT grant_ref_t      *RefPtr
  )
{
  *RefPtr = XenGrantTableGrantAccess (DomainId, Frame, ReadOnly);
  return EFI_SUCCESS;
}

EFI_STATUS
EFIAPI
XenBusGrantEndAccess (
  IN XENBUS_PROTOCOL  *This,
  IN grant_ref_t      Ref
  )
{
  return XenGrantTableEndAccess (Ref);
}