+VmTdExitHandleVe (
+  IN OUT EFI_EXCEPTION_TYPE  *ExceptionType,
+  IN OUT EFI_SYSTEM_CONTEXT  SystemContext
+  )
+{
+  UINT64                    Status;
+  TD_RETURN_DATA            ReturnData;
+  EFI_SYSTEM_CONTEXT_X64    *Regs;
+
+  Regs = SystemContext.SystemContextX64;
+  Status = TdCall (TDCALL_TDGETVEINFO, 0, 0, 0, &ReturnData);
+  ASSERT (Status == 0);
+  if (Status != 0) {
+    DEBUG ((DEBUG_ERROR, "#VE happened. TDGETVEINFO failed with Status = 0x%llx\n", Status));
+    TdVmCall (TDVMCALL_HALT, 0, 0, 0, 0, 0);
+  }

What is the difference between TdVmCall (EXIT_REASON_HLT, 0, 0, 0, 0, 0) vs TdVmCall (TDVMCALL_HALT, 0, 0, 0, 0, 0);

+
+  switch (ReturnData.VeInfo.ExitReason) {
+    case EXIT_REASON_CPUID:
+    Status = CpuIdExit (Regs, &ReturnData.VeInfo);
+    DEBUG ((DEBUG_VERBOSE ,
+          "CPUID #VE happened, ExitReasion is %d, ExitQualification = 0x%x.\n",
+          ReturnData.VeInfo.ExitReason, ReturnData.VeInfo.ExitQualification.Val
+          ));
+    break;
+
+    case EXIT_REASON_HLT:
+    if (FixedPcdGetBool (PcdIgnoreVeHalt) == FALSE) {
+      Status = TdVmCall (EXIT_REASON_HLT, 0, 0, 0, 0, 0);
+    }
+    break;