[tkreuzer] 53665: [HAL] Add a hack to work around a bug in VBox: The APIC emulation requires an iret instruction following closely after writing the EOI register. Since we return from kernel mode t...

Author: tkreuzer
Date: Fri Sep  9 21:10:07 2011
New Revision: 53665
URL: http://svn.reactos.org/svn/reactos?rev=53665&view=rev
Log:
[HAL]
Add a hack to work around a bug in VBox: The APIC emulation requires an iret instruction
following closely after writing the EOI register. Since we return from kernel mode traps
with a jmp (yes you can return from an interrupt with a jmp!) the EOI is never triggered,
making VBox believe we are still serving the interrupt and keeping the PPR on high level,
preventing following interrupts. A small asm stub now does the work of both writing the
EOI and doing an iret.
Modified:
    trunk/reactos/hal/halx86/apic/apic.c
    trunk/reactos/hal/halx86/apic/apictrap.S
Modified: trunk/reactos/hal/halx86/apic/apic.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/hal/halx86/apic/apic.c?rev…
==============================================================================
--- trunk/reactos/hal/halx86/apic/apic.c [iso-8859-1] (original)
+++ trunk/reactos/hal/halx86/apic/apic.c [iso-8859-1] Fri Sep  9 21:10:07 2011
@@ -609,17 +609,22 @@
     return TRUE;
 }
+void HackEoi(void);
+
 VOID
 NTAPI
 HalEndSystemInterrupt(
     IN KIRQL OldIrql,
     IN PKTRAP_FRAME TrapFrame)
 {
+    /* Write 0 to the EndOfInterruptRegister */
+    //ApicWrite(APIC_EOI, 0);
+
+    // HACK!
+    HackEoi();
+
     /* Restore the old IRQL */
     ApicSetCurrentIrql(OldIrql);
-
-    /* Write 0 to the EndOfInterruptRegister */
-    ApicWrite(APIC_EOI, 0);
 }
Modified: trunk/reactos/hal/halx86/apic/apictrap.S
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/hal/halx86/apic/apictrap.S…
==============================================================================
--- trunk/reactos/hal/halx86/apic/apictrap.S [iso-8859-1] (original)
+++ trunk/reactos/hal/halx86/apic/apictrap.S [iso-8859-1] Fri Sep  9 21:10:07 2011
@@ -27,6 +27,18 @@
 TRAP_ENTRY HalpTrap0D, 0
 TRAP_ENTRY HalpApcInterrupt, KI_PUSH_FAKE_ERROR_CODE
 TRAP_ENTRY HalpDispatchInterrupt, KI_PUSH_FAKE_ERROR_CODE
+
+// VBox APIC needs an iret more or less directly following the EOI
+PUBLIC _HackEoi
+_HackEoi:
+    pushfd
+    push cs
+    push offset OnlyOnePersonKnowsHowToHackAroundVBoxBugsAndThatIsNotYou // !!
+    mov dword ptr ds:[HEX(0FFFE00B0)], 0
+    iretd
+OnlyOnePersonKnowsHowToHackAroundVBoxBugsAndThatIsNotYou:
+    ret
+
 #endif
 TRAP_ENTRY HalpClockInterrupt, KI_PUSH_FAKE_ERROR_CODE
 TRAP_ENTRY HalpProfileInterrupt, KI_PUSH_FAKE_ERROR_CODE