OvmfPkg/XenBusDxe/GrantTable.c

   1 /** @file
   2   Grant Table function implementation.
   3
   4   Grant Table are used to grant access to certain page of the current
   5   VM to an other VM.
   6
   7   Author: Steven Smith (sos22@cam.ac.uk)
   8   Changes: Grzegorz Milos (gm281@cam.ac.uk)
   9   Copyright (C) 2006, Cambridge University
  10   Copyright (C) 2014, Citrix Ltd.
  11
  12   SPDX-License-Identifier: BSD-2-Clause-Patent
  13 **/
  14 #include "XenBusDxe.h"
  15
  16 #include <IndustryStandard/Xen/memory.h>
  17
  18 #include <Library/XenHypercallLib.h>
  19 #include <Library/SynchronizationLib.h>
  20
  21 #include "GrantTable.h"
  22
  23 #define NR_RESERVED_ENTRIES 8
  24
  25 #define NR_GRANT_FRAMES (FixedPcdGet32 (PcdXenGrantFrames))
  26 #define NR_GRANT_ENTRIES (NR_GRANT_FRAMES * EFI_PAGE_SIZE / sizeof(grant_entry_v1_t))
  27
  28 STATIC grant_entry_v1_t *GrantTable = NULL;
  29 STATIC grant_ref_t GrantList[NR_GRANT_ENTRIES];
  30 STATIC EFI_LOCK mGrantListLock;
  31 #ifdef GNT_DEBUG
  32 STATIC BOOLEAN GrantInUseList[NR_GRANT_ENTRIES];
  33 #endif
  34
  35 STATIC
  36 VOID
  37 XenGrantTablePutFreeEntry (
  38   grant_ref_t Ref
  39   )
  40 {
  41   EfiAcquireLock (&mGrantListLock);
  42 #ifdef GNT_DEBUG
  43   ASSERT (GrantInUseList[Ref]);
  44   GrantInUseList[Ref] = FALSE;
  45 #endif
  46   GrantList[Ref] = GrantList[0];
  47   GrantList[0] = Ref;
  48   EfiReleaseLock (&mGrantListLock);
  49 }
  50
  51 STATIC
  52 grant_ref_t
  53 XenGrantTableGetFreeEntry (
  54   VOID
  55   )
  56 {
  57   grant_ref_t Ref;
  58
  59   EfiAcquireLock (&mGrantListLock);
  60   Ref = GrantList[0];
  61   ASSERT (Ref >= NR_RESERVED_ENTRIES && Ref < NR_GRANT_ENTRIES);
  62   GrantList[0] = GrantList[Ref];
  63 #ifdef GNT_DEBUG
  64   ASSERT (!GrantInUseList[Ref]);
  65   GrantInUseList[Ref] = TRUE;
  66 #endif
  67   EfiReleaseLock (&mGrantListLock);
  68   return Ref;
  69 }
  70
  71 STATIC
  72 grant_ref_t
  73 XenGrantTableGrantAccess (
  74   IN domid_t  DomainId,
  75   IN UINTN    Frame,
  76   IN BOOLEAN  ReadOnly
  77   )
  78 {
  79   grant_ref_t Ref;
  80   UINT16 Flags;
  81
  82   ASSERT (GrantTable != NULL);
  83   Ref = XenGrantTableGetFreeEntry ();
  84   GrantTable[Ref].frame = (UINT32)Frame;
  85   GrantTable[Ref].domid = DomainId;
  86   MemoryFence ();
  87   Flags = GTF_permit_access;
  88   if (ReadOnly) {
  89     Flags |= GTF_readonly;
  90   }
  91   GrantTable[Ref].flags = Flags;
  92
  93   return Ref;
  94 }
  95
  96 STATIC
  97 EFI_STATUS
  98 XenGrantTableEndAccess (
  99   grant_ref_t Ref
 100   )
 101 {
 102   UINT16 Flags, OldFlags;
 103
 104   ASSERT (GrantTable != NULL);
 105   ASSERT (Ref >= NR_RESERVED_ENTRIES && Ref < NR_GRANT_ENTRIES);
 106
 107   OldFlags = GrantTable[Ref].flags;
 108   do {
 109     if ((Flags = OldFlags) & (GTF_reading | GTF_writing)) {
 110       DEBUG ((DEBUG_WARN, "WARNING: g.e. still in use! (%x)\n", Flags));
 111       return EFI_NOT_READY;
 112     }
 113     OldFlags = InterlockedCompareExchange16 (&GrantTable[Ref].flags, Flags, 0);
 114   } while (OldFlags != Flags);
 115
 116   XenGrantTablePutFreeEntry (Ref);
 117   return EFI_SUCCESS;
 118 }
 119
 120 VOID
 121 XenGrantTableInit (
 122   IN XENBUS_DEVICE  *Dev
 123   )
 124 {
 125   xen_add_to_physmap_t Parameters;
 126   INTN Index;
 127   INTN ReturnCode;
 128
 129 #ifdef GNT_DEBUG
 130   SetMem(GrantInUseList, sizeof (GrantInUseList), 1);
 131 #endif
 132   EfiInitializeLock (&mGrantListLock, TPL_NOTIFY);
 133   for (Index = NR_RESERVED_ENTRIES; Index < NR_GRANT_ENTRIES; Index++) {
 134     XenGrantTablePutFreeEntry ((grant_ref_t)Index);
 135   }
 136
 137   GrantTable = (VOID*)(UINTN) Dev->XenIo->GrantTableAddress;
 138   for (Index = 0; Index < NR_GRANT_FRAMES; Index++) {
 139     Parameters.domid = DOMID_SELF;
 140     Parameters.idx = Index;
 141     Parameters.space = XENMAPSPACE_grant_table;
 142     Parameters.gpfn = (xen_pfn_t) ((UINTN) GrantTable >> EFI_PAGE_SHIFT) + Index;
 143     ReturnCode = XenHypercallMemoryOp (XENMEM_add_to_physmap, &Parameters);
 144     if (ReturnCode != 0) {
 145       DEBUG ((DEBUG_ERROR,
 146         "Xen GrantTable, add_to_physmap hypercall error: %Ld\n",
 147         (INT64)ReturnCode));
 148     }
 149   }
 150 }
 151
 152 VOID
 153 XenGrantTableDeinit (
 154   XENBUS_DEVICE *Dev
 155   )
 156 {
 157   INTN ReturnCode, Index;
 158   xen_remove_from_physmap_t Parameters;
 159
 160   if (GrantTable == NULL) {
 161     return;
 162   }
 163
 164   for (Index = NR_GRANT_FRAMES - 1; Index >= 0; Index--) {
 165     Parameters.domid = DOMID_SELF;
 166     Parameters.gpfn = (xen_pfn_t) ((UINTN) GrantTable >> EFI_PAGE_SHIFT) + Index;
 167     DEBUG ((DEBUG_INFO, "Xen GrantTable, removing %Lx\n",
 168       (UINT64)Parameters.gpfn));
 169     ReturnCode = XenHypercallMemoryOp (XENMEM_remove_from_physmap, &Parameters);
 170     if (ReturnCode != 0) {
 171       DEBUG ((DEBUG_ERROR,
 172         "Xen GrantTable, remove_from_physmap hypercall error: %Ld\n",
 173         (INT64)ReturnCode));
 174     }
 175   }
 176   GrantTable = NULL;
 177 }
 178
 179 EFI_STATUS
 180 EFIAPI
 181 XenBusGrantAccess (
 182   IN  XENBUS_PROTOCOL *This,
 183   IN  domid_t         DomainId,
 184   IN  UINTN           Frame, // MFN
 185   IN  BOOLEAN         ReadOnly,
 186   OUT grant_ref_t     *RefPtr
 187   )
 188 {
 189   *RefPtr = XenGrantTableGrantAccess (DomainId, Frame, ReadOnly);
 190   return EFI_SUCCESS;
 191 }
 192
 193 EFI_STATUS
 194 EFIAPI
 195 XenBusGrantEndAccess (
 196   IN XENBUS_PROTOCOL  *This,
 197   IN grant_ref_t      Ref
 198   )
 199 {
 200   return XenGrantTableEndAccess (Ref);
 201 }