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   Redistribution and use in source and binary forms, with or without
  13   modification, are permitted provided that the following conditions
  14   are met:
  15   1. Redistributions of source code must retain the above copyright
  16      notice, this list of conditions and the following disclaimer.
  17   2. Redistributions in binary form must reproduce the above copyright
  18      notice, this list of conditions and the following disclaimer in the
  19      documentation and/or other materials provided with the distribution.
  20
  21   THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  22   ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24   ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
  25   FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27   OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29   LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30   OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31   SUCH DAMAGE.
  32 **/
  33 #include "XenBusDxe.h"
  34
  35 #include <IndustryStandard/Xen/memory.h>
  36
  37 #include <Library/XenHypercallLib.h>
  38 #include <Library/SynchronizationLib.h>
  39
  40 #include "GrantTable.h"
  41
  42 #define NR_RESERVED_ENTRIES 8
  43
  44 /* NR_GRANT_FRAMES must be less than or equal to that configured in Xen */
  45 #define NR_GRANT_FRAMES 4
  46 #define NR_GRANT_ENTRIES (NR_GRANT_FRAMES * EFI_PAGE_SIZE / sizeof(grant_entry_v1_t))
  47
  48 STATIC grant_entry_v1_t *GrantTable = NULL;
  49 STATIC grant_ref_t GrantList[NR_GRANT_ENTRIES];
  50 STATIC EFI_LOCK mGrantListLock;
  51 #ifdef GNT_DEBUG
  52 STATIC BOOLEAN GrantInUseList[NR_GRANT_ENTRIES];
  53 #endif
  54
  55 STATIC
  56 VOID
  57 XenGrantTablePutFreeEntry (
  58   grant_ref_t Ref
  59   )
  60 {
  61   EfiAcquireLock (&mGrantListLock);
  62 #ifdef GNT_DEBUG
  63   ASSERT (GrantInUseList[Ref]);
  64   GrantInUseList[Ref] = FALSE;
  65 #endif
  66   GrantList[Ref] = GrantList[0];
  67   GrantList[0] = Ref;
  68   EfiReleaseLock (&mGrantListLock);
  69 }
  70
  71 STATIC
  72 grant_ref_t
  73 XenGrantTableGetFreeEntry (
  74   VOID
  75   )
  76 {
  77   grant_ref_t Ref;
  78
  79   EfiAcquireLock (&mGrantListLock);
  80   Ref = GrantList[0];
  81   ASSERT (Ref >= NR_RESERVED_ENTRIES && Ref < NR_GRANT_ENTRIES);
  82   GrantList[0] = GrantList[Ref];
  83 #ifdef GNT_DEBUG
  84   ASSERT (!GrantInUseList[Ref]);
  85   GrantInUseList[Ref] = TRUE;
  86 #endif
  87   EfiReleaseLock (&mGrantListLock);
  88   return Ref;
  89 }
  90
  91 STATIC
  92 grant_ref_t
  93 XenGrantTableGrantAccess (
  94   IN domid_t  DomainId,
  95   IN UINTN    Frame,
  96   IN BOOLEAN  ReadOnly
  97   )
  98 {
  99   grant_ref_t Ref;
 100   UINT16 Flags;
 101
 102   ASSERT (GrantTable != NULL);
 103   Ref = XenGrantTableGetFreeEntry ();
 104   GrantTable[Ref].frame = (UINT32)Frame;
 105   GrantTable[Ref].domid = DomainId;
 106   MemoryFence ();
 107   Flags = GTF_permit_access;
 108   if (ReadOnly) {
 109     Flags |= GTF_readonly;
 110   }
 111   GrantTable[Ref].flags = Flags;
 112
 113   return Ref;
 114 }
 115
 116 STATIC
 117 EFI_STATUS
 118 XenGrantTableEndAccess (
 119   grant_ref_t Ref
 120   )
 121 {
 122   UINT16 Flags, OldFlags;
 123
 124   ASSERT (GrantTable != NULL);
 125   ASSERT (Ref >= NR_RESERVED_ENTRIES && Ref < NR_GRANT_ENTRIES);
 126
 127   OldFlags = GrantTable[Ref].flags;
 128   do {
 129     if ((Flags = OldFlags) & (GTF_reading | GTF_writing)) {
 130       DEBUG ((EFI_D_WARN, "WARNING: g.e. still in use! (%x)\n", Flags));
 131       return EFI_NOT_READY;
 132     }
 133     OldFlags = InterlockedCompareExchange16 (&GrantTable[Ref].flags, Flags, 0);
 134   } while (OldFlags != Flags);
 135
 136   XenGrantTablePutFreeEntry (Ref);
 137   return EFI_SUCCESS;
 138 }
 139
 140 VOID
 141 XenGrantTableInit (
 142   IN XENBUS_DEVICE  *Dev
 143   )
 144 {
 145   xen_add_to_physmap_t Parameters;
 146   INTN Index;
 147   INTN ReturnCode;
 148
 149 #ifdef GNT_DEBUG
 150   SetMem(GrantInUseList, sizeof (GrantInUseList), 1);
 151 #endif
 152   EfiInitializeLock (&mGrantListLock, TPL_NOTIFY);
 153   for (Index = NR_RESERVED_ENTRIES; Index < NR_GRANT_ENTRIES; Index++) {
 154     XenGrantTablePutFreeEntry ((grant_ref_t)Index);
 155   }
 156
 157   GrantTable = (VOID*)(UINTN) Dev->XenIo->GrantTableAddress;
 158   for (Index = 0; Index < NR_GRANT_FRAMES; Index++) {
 159     Parameters.domid = DOMID_SELF;
 160     Parameters.idx = Index;
 161     Parameters.space = XENMAPSPACE_grant_table;
 162     Parameters.gpfn = (xen_pfn_t) ((UINTN) GrantTable >> EFI_PAGE_SHIFT) + Index;
 163     ReturnCode = XenHypercallMemoryOp (XENMEM_add_to_physmap, &Parameters);
 164     if (ReturnCode != 0) {
 165       DEBUG ((EFI_D_ERROR,
 166         "Xen GrantTable, add_to_physmap hypercall error: %Ld\n",
 167         (INT64)ReturnCode));
 168     }
 169   }
 170 }
 171
 172 VOID
 173 XenGrantTableDeinit (
 174   XENBUS_DEVICE *Dev
 175   )
 176 {
 177   INTN ReturnCode, Index;
 178   xen_remove_from_physmap_t Parameters;
 179
 180   if (GrantTable == NULL) {
 181     return;
 182   }
 183
 184   for (Index = NR_GRANT_FRAMES - 1; Index >= 0; Index--) {
 185     Parameters.domid = DOMID_SELF;
 186     Parameters.gpfn = (xen_pfn_t) ((UINTN) GrantTable >> EFI_PAGE_SHIFT) + Index;
 187     DEBUG ((EFI_D_INFO, "Xen GrantTable, removing %Lx\n",
 188       (UINT64)Parameters.gpfn));
 189     ReturnCode = XenHypercallMemoryOp (XENMEM_remove_from_physmap, &Parameters);
 190     if (ReturnCode != 0) {
 191       DEBUG ((EFI_D_ERROR,
 192         "Xen GrantTable, remove_from_physmap hypercall error: %Ld\n",
 193         (INT64)ReturnCode));
 194     }
 195   }
 196   GrantTable = NULL;
 197 }
 198
 199 EFI_STATUS
 200 EFIAPI
 201 XenBusGrantAccess (
 202   IN  XENBUS_PROTOCOL *This,
 203   IN  domid_t         DomainId,
 204   IN  UINTN           Frame, // MFN
 205   IN  BOOLEAN         ReadOnly,
 206   OUT grant_ref_t     *RefPtr
 207   )
 208 {
 209   *RefPtr = XenGrantTableGrantAccess (DomainId, Frame, ReadOnly);
 210   return EFI_SUCCESS;
 211 }
 212
 213 EFI_STATUS
 214 EFIAPI
 215 XenBusGrantEndAccess (
 216   IN XENBUS_PROTOCOL  *This,
 217   IN grant_ref_t      Ref
 218   )
 219 {
 220   return XenGrantTableEndAccess (Ref);
 221 }