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OvmfPkg: Send EOI before RestoreTPL() in timer interrupt handlers 

Deferring the EOI until after the call to RestoreTPL() means that any
callbacks invoked by RestoreTPL() will run with timer interrupt
delivery disabled.  If any such callbacks themselves rely on timers to
implement timeout loops, then the callbacks will get stuck in an
infinite loop from which the system will never recover.

This reverts commit 239b50a86 ("OvmfPkg: End timer interrupt later to
avoid stack overflow under load").

Cc: Paolo Bonzini <pbonzini@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=4162
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Acked-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
Michael Brown 2022-12-09 10:20:21 +00:00 committed by mergify[bot]
parent bf65d7ee88
commit 9bf473da4c
2 changed files with 4 additions and 6 deletions
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5
OvmfPkg/8254TimerDxe/Timer.c
View File

@ -80,6 +80,8 @@ TimerInterruptHandler (
OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
mLegacy8259->EndOfInterrupt (mLegacy8259, Efi8259Irq0);
if (mTimerNotifyFunction != NULL) {
//
// @bug : This does not handle missed timer interrupts
@ -88,9 +90,6 @@ TimerInterruptHandler (
}
gBS->RestoreTPL (OriginalTPL);
DisableInterrupts ();
mLegacy8259->EndOfInterrupt (mLegacy8259, Efi8259Irq0);
}
/**

5
OvmfPkg/LocalApicTimerDxe/LocalApicTimerDxe.c
View File

@ -62,6 +62,8 @@ TimerInterruptHandler (
OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
SendApicEoi ();
if (mTimerNotifyFunction != NULL) {
//
// @bug : This does not handle missed timer interrupts
@ -70,9 +72,6 @@ TimerInterruptHandler (
}
gBS->RestoreTPL (OriginalTPL);
DisableInterrupts ();
SendApicEoi ();
}
/**