C++ (Cpp) UtilWriteMsr64 Examples

Example #1

File: vmm.cpp Project: Garfield-Chen/HyperPlatform

// RDMSR and WRMSR
_Use_decl_annotations_ static void VmmpHandleMsrAccess(
    GuestContext *guest_context, bool read_access) {
  // Apply it for VMCS instead of a real MSR if a speficied MSR is either of
  // them.
  const auto msr = static_cast<Msr>(guest_context->gp_regs->cx);

  bool transfer_to_vmcs = false;
  VmcsField vmcs_field = {};
  switch (msr) {
    case Msr::kIa32SysenterCs:
      vmcs_field = VmcsField::kGuestSysenterCs;
      transfer_to_vmcs = true;
      break;
    case Msr::kIa32SysenterEsp:
      vmcs_field = VmcsField::kGuestSysenterEsp;
      transfer_to_vmcs = true;
      break;
    case Msr::kIa32SysenterEip:
      vmcs_field = VmcsField::kGuestSysenterEip;
      transfer_to_vmcs = true;
      break;
    case Msr::kIa32GsBase:
      vmcs_field = VmcsField::kGuestGsBase;
      transfer_to_vmcs = true;
      break;
    case Msr::kIa32FsBase:
      vmcs_field = VmcsField::kGuestFsBase;
      break;
    default:
      break;
  }
  // Do not shadow 64bit fields because the current implmentation for x86 is not
  // able to handle it due to a simple use of UtilVmWrite() below.
  NT_ASSERT(UtilIsInBounds(vmcs_field, VmcsField::kIoBitmapA,
                           VmcsField::kHostIa32PerfGlobalCtrlHigh) == false);

  // This unconditional __readmsr and __writemsr may cause #GP resulting in
  // bug check. A proper way to solve this is check supported MSR values
  // beforehand and inject an exception when unsupported MSR values are given.
  LARGE_INTEGER msr_value = {};
  if (read_access) {
    if (transfer_to_vmcs) {
      msr_value.QuadPart = UtilVmRead(vmcs_field);
    } else {
      msr_value.QuadPart = UtilReadMsr64(msr);
    }
    guest_context->gp_regs->ax = msr_value.LowPart;
    guest_context->gp_regs->dx = msr_value.HighPart;
  } else {
    msr_value.LowPart = static_cast<ULONG>(guest_context->gp_regs->ax);
    msr_value.HighPart = static_cast<ULONG>(guest_context->gp_regs->dx);
    if (transfer_to_vmcs) {
      UtilVmWrite(vmcs_field, static_cast<ULONG_PTR>(msr_value.QuadPart));
    } else {
      UtilWriteMsr64(msr, msr_value.QuadPart);
    }
  }

  VmmpAdjustGuestInstructionPointer(guest_context->ip);
}

Example #2

File: vm.cpp Project: Rootkitsmm/HyperPlatform

// Sets 1 to the lock bit of the IA32_FEATURE_CONTROL MSR
_Use_decl_annotations_ static NTSTATUS VmpSetLockBitCallback(void *context) {
  UNREFERENCED_PARAMETER(context);

  Ia32FeatureControlMsr vmx_feature_control = {
      UtilReadMsr64(Msr::kIa32FeatureControl)};
  if (vmx_feature_control.fields.lock) {
    return STATUS_SUCCESS;
  }
  vmx_feature_control.fields.lock = true;
  UtilWriteMsr64(Msr::kIa32FeatureControl, vmx_feature_control.all);
  vmx_feature_control.all = UtilReadMsr64(Msr::kIa32FeatureControl);
  if (!vmx_feature_control.fields.lock) {
    HYPERPLATFORM_LOG_ERROR("The lock bit is still clear.");
    return STATUS_DEVICE_CONFIGURATION_ERROR;
  }
  return STATUS_SUCCESS;
}