fix a few bugs in scheduling and synchronization, separate OVMF_VARS for debug

code/kernel/ke_switch.asm

@@ -64,9 +64,14 @@ KeSwitchContext ENDP
 ;
 ; We load RCX from the stack (first arg per MS x64), then IRETQ.
 ; -------------------------------------------------------------------------
+EXTERN KeSchedulerPostSwitch : PROC
+
 KeThreadEntry PROC
-    pop     rcx        ; user arg
-    iretq              ; pops RIP, CS, RFLAGS, RSP, SS -> ring 3
+    sub     rsp, 32    ; Reserve shadow space
+    call    KeSchedulerPostSwitch
+    add     rsp, 32
+    pop     rcx        ; load user arg
+    iretq              ; -> ring 3
 KeThreadEntry ENDP
 
 END