OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxe.c

   1 /** @file
   2
   3   Stateful and implicitly initialized fw_cfg library implementation.
   4
   5   Copyright (C) 2013, Red Hat, Inc.
   6   Copyright (c) 2011 - 2013, Intel Corporation. All rights reserved.<BR>
   7   Copyright (c) 2017, Advanced Micro Devices. All rights reserved.<BR>
   8
   9   This program and the accompanying materials are licensed and made available
  10   under the terms and conditions of the BSD License which accompanies this
  11   distribution.  The full text of the license may be found at
  12   http://opensource.org/licenses/bsd-license.php
  13
  14   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
  15   WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  16 **/
  17
  18 #include <Uefi.h>
  19
  20 #include <Protocol/IoMmu.h>
  21
  22 #include <Library/BaseLib.h>
  23 #include <Library/DebugLib.h>
  24 #include <Library/QemuFwCfgLib.h>
  25 #include <Library/UefiBootServicesTableLib.h>
  26 #include <Library/MemEncryptSevLib.h>
  27
  28 #include "QemuFwCfgLibInternal.h"
  29
  30 STATIC BOOLEAN mQemuFwCfgSupported = FALSE;
  31 STATIC BOOLEAN mQemuFwCfgDmaSupported;
  32
  33 STATIC EDKII_IOMMU_PROTOCOL        *mIoMmuProtocol;
  34 /**
  35
  36  Returns a boolean indicating whether SEV is enabled
  37
  38  @retval    TRUE    SEV is enabled
  39  @retval    FALSE   SEV is disabled
  40 **/
  41 BOOLEAN
  42 InternalQemuFwCfgSevIsEnabled (
  43   VOID
  44   )
  45 {
  46   return MemEncryptSevIsEnabled ();
  47 }
  48
  49 /**
  50   Returns a boolean indicating if the firmware configuration interface
  51   is available or not.
  52
  53   This function may change fw_cfg state.
  54
  55   @retval    TRUE   The interface is available
  56   @retval    FALSE  The interface is not available
  57
  58 **/
  59 BOOLEAN
  60 EFIAPI
  61 QemuFwCfgIsAvailable (
  62   VOID
  63   )
  64 {
  65   return InternalQemuFwCfgIsAvailable ();
  66 }
  67
  68
  69 RETURN_STATUS
  70 EFIAPI
  71 QemuFwCfgInitialize (
  72   VOID
  73   )
  74 {
  75   UINT32 Signature;
  76   UINT32 Revision;
  77
  78   //
  79   // Enable the access routines while probing to see if it is supported.
  80   // For probing we always use the IO Port (IoReadFifo8()) access method.
  81   //
  82   mQemuFwCfgSupported = TRUE;
  83   mQemuFwCfgDmaSupported = FALSE;
  84
  85   QemuFwCfgSelectItem (QemuFwCfgItemSignature);
  86   Signature = QemuFwCfgRead32 ();
  87   DEBUG ((EFI_D_INFO, "FW CFG Signature: 0x%x\n", Signature));
  88   QemuFwCfgSelectItem (QemuFwCfgItemInterfaceVersion);
  89   Revision = QemuFwCfgRead32 ();
  90   DEBUG ((EFI_D_INFO, "FW CFG Revision: 0x%x\n", Revision));
  91   if ((Signature != SIGNATURE_32 ('Q', 'E', 'M', 'U')) ||
  92       (Revision < 1)
  93      ) {
  94     DEBUG ((EFI_D_INFO, "QemuFwCfg interface not supported.\n"));
  95     mQemuFwCfgSupported = FALSE;
  96     return RETURN_SUCCESS;
  97   }
  98
  99   if ((Revision & FW_CFG_F_DMA) == 0) {
 100     DEBUG ((DEBUG_INFO, "QemuFwCfg interface (IO Port) is supported.\n"));
 101   } else {
 102     mQemuFwCfgDmaSupported = TRUE;
 103     DEBUG ((DEBUG_INFO, "QemuFwCfg interface (DMA) is supported.\n"));
 104   }
 105
 106   if (mQemuFwCfgDmaSupported && MemEncryptSevIsEnabled ()) {
 107     EFI_STATUS   Status;
 108
 109     //
 110     // IoMmuDxe driver must have installed the IOMMU protocol. If we are not
 111     // able to locate the protocol then something must have gone wrong.
 112     //
 113     Status = gBS->LocateProtocol (&gEdkiiIoMmuProtocolGuid, NULL, (VOID **)&mIoMmuProtocol);
 114     if (EFI_ERROR (Status)) {
 115       DEBUG ((DEBUG_ERROR,
 116         "QemuFwCfgSevDma %a:%a Failed to locate IOMMU protocol.\n",
 117         gEfiCallerBaseName, __FUNCTION__));
 118       ASSERT (FALSE);
 119       CpuDeadLoop ();
 120     }
 121   }
 122
 123   return RETURN_SUCCESS;
 124 }
 125
 126
 127 /**
 128   Returns a boolean indicating if the firmware configuration interface is
 129   available for library-internal purposes.
 130
 131   This function never changes fw_cfg state.
 132
 133   @retval    TRUE   The interface is available internally.
 134   @retval    FALSE  The interface is not available internally.
 135 **/
 136 BOOLEAN
 137 InternalQemuFwCfgIsAvailable (
 138   VOID
 139   )
 140 {
 141   return mQemuFwCfgSupported;
 142 }
 143
 144 /**
 145   Returns a boolean indicating whether QEMU provides the DMA-like access method
 146   for fw_cfg.
 147
 148   @retval    TRUE   The DMA-like access method is available.
 149   @retval    FALSE  The DMA-like access method is unavailable.
 150 **/
 151 BOOLEAN
 152 InternalQemuFwCfgDmaIsAvailable (
 153   VOID
 154   )
 155 {
 156   return mQemuFwCfgDmaSupported;
 157 }
 158
 159 /**
 160  Allocate a bounce buffer for SEV DMA.
 161
 162   @param[in]     NumPage  Number of pages.
 163   @param[out]    Buffer   Allocated DMA Buffer pointer
 164
 165 **/
 166 VOID
 167 InternalQemuFwCfgSevDmaAllocateBuffer (
 168   OUT    VOID     **Buffer,
 169   IN     UINT32   NumPages
 170   )
 171 {
 172   EFI_STATUS    Status;
 173
 174   ASSERT (mIoMmuProtocol != NULL);
 175
 176   Status = mIoMmuProtocol->AllocateBuffer (
 177                             mIoMmuProtocol,
 178                             0,
 179                             EfiBootServicesData,
 180                             NumPages,
 181                             Buffer,
 182                             EDKII_IOMMU_ATTRIBUTE_MEMORY_CACHED
 183                           );
 184   if (EFI_ERROR (Status)) {
 185     DEBUG ((DEBUG_ERROR,
 186       "%a:%a failed to allocate %u pages\n", gEfiCallerBaseName, __FUNCTION__,
 187       NumPages));
 188     ASSERT (FALSE);
 189     CpuDeadLoop ();
 190   }
 191
 192   DEBUG ((DEBUG_VERBOSE,
 193     "%a:%a buffer 0x%Lx Pages %u\n", gEfiCallerBaseName, __FUNCTION__,
 194     (UINT64)(UINTN)Buffer, NumPages));
 195 }
 196
 197 /**
 198  Free the DMA buffer allocated using InternalQemuFwCfgSevDmaAllocateBuffer
 199
 200   @param[in]     NumPage  Number of pages.
 201   @param[in]     Buffer   DMA Buffer pointer
 202
 203 **/
 204 VOID
 205 InternalQemuFwCfgSevDmaFreeBuffer (
 206   IN     VOID     *Buffer,
 207   IN     UINT32   NumPages
 208   )
 209 {
 210   EFI_STATUS    Status;
 211
 212   ASSERT (mIoMmuProtocol != NULL);
 213
 214   Status = mIoMmuProtocol->FreeBuffer (
 215                             mIoMmuProtocol,
 216                             NumPages,
 217                             Buffer
 218                           );
 219   if (EFI_ERROR (Status)) {
 220     DEBUG ((DEBUG_ERROR,
 221       "%a:%a failed to free buffer 0x%Lx pages %u\n", gEfiCallerBaseName,
 222       __FUNCTION__, (UINT64)(UINTN)Buffer, NumPages));
 223     ASSERT (FALSE);
 224     CpuDeadLoop ();
 225   }
 226
 227   DEBUG ((DEBUG_VERBOSE,
 228     "%a:%a buffer 0x%Lx Pages %u\n", gEfiCallerBaseName,__FUNCTION__,
 229     (UINT64)(UINTN)Buffer, NumPages));
 230 }