From: Alexei Fedorov <alexei.fedorov@arm.com>
Date: Mon, 8 Aug 2016 13:46:00 +0000 (+0200)
Subject: ArmPkg/ArmGicDxe: Fix double GIC EIOR write per interrupt
X-Git-Tag: edk2-stable201903~6094
X-Git-Url: https://git.proxmox.com/?p=mirror_edk2.git;a=commitdiff_plain;h=7989300df75f274203d74266811089aaa11b517c

ArmPkg/ArmGicDxe: Fix double GIC EIOR write per interrupt

This commit fixes a bug in the GIC v2 and v3 drivers where the GICC_EOIR
(End Of Interrupt Register) is written twice for a single interrupt.
GicV(2|3)IrqInterruptHandler() calls the Interrupt Handler and then
GicV(2|3)EndOfInterrupt() on exit:

 InterruptHandler = gRegisteredInterruptHandlers[GicInterrupt];
 if (InterruptHandler != NULL) {
   // Call the registered interrupt handler.
   InterruptHandler (GicInterrupt, SystemContext);
 } else {
   DEBUG ((EFI_D_ERROR, "Spurious GIC interrupt: 0x%x\n", GicInterrupt));
 }

 GicV2EndOfInterrupt (&gHardwareInterruptV2Protocol, GicInterrupt);

although gInterrupt->EndOfInterrupt() can be expected to have already
been called by InterruptHandler() [which is the case for the primary
in-tree handler in TimerDxe]

The fix moves the EndOfInterrupt() call inside the else case for
unregistered/spurious interrupts. This removes a potential race
condition that might have lost interrupts.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Alexei Fedorov <alexei.fedorov@arm.com>
Signed-off-by: Evan Lloyd <evan.lloyd@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---

diff --git a/ArmPkg/Drivers/ArmGic/GicV2/ArmGicV2Dxe.c b/ArmPkg/Drivers/ArmGic/GicV2/ArmGicV2Dxe.c
index 036eb5cd6b..34d4be3867 100644
--- a/ArmPkg/Drivers/ArmGic/GicV2/ArmGicV2Dxe.c
+++ b/ArmPkg/Drivers/ArmGic/GicV2/ArmGicV2Dxe.c
@@ -2,7 +2,7 @@
 
 Copyright (c) 2009, Hewlett-Packard Company. All rights reserved.<BR>
 Portions copyright (c) 2010, Apple Inc. All rights reserved.<BR>
-Portions copyright (c) 2011-2015, ARM Ltd. All rights reserved.<BR>
+Portions copyright (c) 2011-2016, ARM Ltd. All rights reserved.<BR>
 
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
@@ -178,9 +178,8 @@ GicV2IrqInterruptHandler (
     InterruptHandler (GicInterrupt, SystemContext);
   } else {
     DEBUG ((EFI_D_ERROR, "Spurious GIC interrupt: 0x%x\n", GicInterrupt));
+    GicV2EndOfInterrupt (&gHardwareInterruptV2Protocol, GicInterrupt);
   }
-
-  GicV2EndOfInterrupt (&gHardwareInterruptV2Protocol, GicInterrupt);
 }
 
 //
diff --git a/ArmPkg/Drivers/ArmGic/GicV3/ArmGicV3Dxe.c b/ArmPkg/Drivers/ArmGic/GicV3/ArmGicV3Dxe.c
index 106c669fcb..983936f373 100644
--- a/ArmPkg/Drivers/ArmGic/GicV3/ArmGicV3Dxe.c
+++ b/ArmPkg/Drivers/ArmGic/GicV3/ArmGicV3Dxe.c
@@ -1,6 +1,6 @@
 /** @file
 *
-*  Copyright (c) 2011-2015, ARM Limited. All rights reserved.
+*  Copyright (c) 2011-2016, ARM Limited. All rights reserved.
 *
 *  This program and the accompanying materials
 *  are licensed and made available under the terms and conditions of the BSD License
@@ -169,9 +169,8 @@ GicV3IrqInterruptHandler (
     InterruptHandler (GicInterrupt, SystemContext);
   } else {
     DEBUG ((EFI_D_ERROR, "Spurious GIC interrupt: 0x%x\n", GicInterrupt));
+    GicV3EndOfInterrupt (&gHardwareInterruptV3Protocol, GicInterrupt);
   }
-
-  GicV3EndOfInterrupt (&gHardwareInterruptV3Protocol, GicInterrupt);
 }
 
 //