OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c

   1 /** @file
   2   X64 #VC Exception Handler functon.
   3
   4   Copyright (C) 2020, Advanced Micro Devices, Inc. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include <Base.h>
  10 #include <Uefi.h>
  11 #include <Library/BaseMemoryLib.h>
  12 #include <Library/VmgExitLib.h>
  13 #include <Register/Amd/Msr.h>
  14
  15 /**
  16   Handle a #VC exception.
  17
  18   Performs the necessary processing to handle a #VC exception.
  19
  20   @param[in, out]  ExceptionType  Pointer to an EFI_EXCEPTION_TYPE to be set
  21                                   as value to use on error.
  22   @param[in, out]  SystemContext  Pointer to EFI_SYSTEM_CONTEXT
  23
  24   @retval  EFI_SUCCESS            Exception handled
  25   @retval  EFI_UNSUPPORTED        #VC not supported, (new) exception value to
  26                                   propagate provided
  27   @retval  EFI_PROTOCOL_ERROR     #VC handling failed, (new) exception value to
  28                                   propagate provided
  29
  30 **/
  31 EFI_STATUS
  32 EFIAPI
  33 VmgExitHandleVc (
  34   IN OUT EFI_EXCEPTION_TYPE  *ExceptionType,
  35   IN OUT EFI_SYSTEM_CONTEXT  SystemContext
  36   )
  37 {
  38   MSR_SEV_ES_GHCB_REGISTER  Msr;
  39   EFI_SYSTEM_CONTEXT_X64    *Regs;
  40   GHCB                      *Ghcb;
  41   UINT64                    ExitCode, Status;
  42   EFI_STATUS                VcRet;
  43
  44   VcRet = EFI_SUCCESS;
  45
  46   Msr.GhcbPhysicalAddress = AsmReadMsr64 (MSR_SEV_ES_GHCB);
  47   ASSERT (Msr.GhcbInfo.Function == 0);
  48   ASSERT (Msr.Ghcb != 0);
  49
  50   Regs = SystemContext.SystemContextX64;
  51   Ghcb = Msr.Ghcb;
  52
  53   VmgInit (Ghcb);
  54
  55   ExitCode = Regs->ExceptionData;
  56   switch (ExitCode) {
  57   default:
  58     Status = VmgExit (Ghcb, SVM_EXIT_UNSUPPORTED, ExitCode, 0);
  59     if (Status == 0) {
  60       Regs->ExceptionData = 0;
  61       *ExceptionType = GP_EXCEPTION;
  62     } else {
  63       GHCB_EVENT_INJECTION  Event;
  64
  65       Event.Uint64 = Status;
  66       if (Event.Elements.ErrorCodeValid != 0) {
  67         Regs->ExceptionData = Event.Elements.ErrorCode;
  68       } else {
  69         Regs->ExceptionData = 0;
  70       }
  71
  72       *ExceptionType = Event.Elements.Vector;
  73     }
  74
  75     VcRet = EFI_PROTOCOL_ERROR;
  76   }
  77
  78   VmgDone (Ghcb);
  79
  80   return VcRet;
  81 }