Reserve initial thread frame space in AP startup stack

xtoskrnl/hl/x86/cpu.cc

@@ -174,6 +174,7 @@ HL::Cpu::StartAllProcessors(VOID)
         StartBlock->Cr3 = AR::CpuFunctions::ReadControlRegister(3);
         StartBlock->Cr4 = AR::CpuFunctions::ReadControlRegister(4);
         StartBlock->EntryPoint = (PVOID)&KE::KernelInit::BootstrapApplicationProcessor;
+        StartBlock->InitialStack = (PVOID)((ULONG_PTR)StartBlock->Stack - KTHREAD_STACK_INITIAL_RESERVE);
         StartBlock->ProcessorStructures = CpuStructures;
         StartBlock->Started = FALSE;