ArmPkg/ArmGicDxe: Use EOImode 0x0 on GICv3

When re-entering EDK2 from a high level OS such as Linux, the GICv3 may
be configured to use split priority drop and deactivate (EOImode == 1),
whereas EDK2's GICv3 driver assumes the default setting of EOImode == 0.

So clear the EOImode bit explicitly when taking control of the GIC.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

ArmPkg/Drivers/ArmGicDxe/ArmGicDxe.h

@@ -139,4 +139,14 @@ ArmGicV3SetPriorityMask (
   IN UINTN  Priority
   );
 
+UINTN
+ArmGicV3GetControlRegister (
+  VOID
+  );
+
+VOID
+ArmGicV3SetControlRegister (
+  IN UINTN  Value
+  );
+
 #endif // ARM_GIC_DXE_H_

ArmPkg/Drivers/ArmGicDxe/GicV3/AArch64/ArmGicV3.S

@@ -22,6 +22,7 @@
 #define ICC_IAR1_EL1            S3_0_C12_C12_0
 #define ICC_PMR_EL1             S3_0_C4_C6_0
 #define ICC_BPR1_EL1            S3_0_C12_C12_3
+#define ICC_CTLR_EL1            S3_0_C12_C12_4
 
 #endif
 
@@ -99,3 +100,19 @@ ASM_FUNC(ArmGicV3SetPriorityMask)
 ASM_FUNC(ArmGicV3SetBinaryPointer)
         msr     ICC_BPR1_EL1, x0
         ret
+
+//UINTN
+//ArmGicV3GetControlRegister(
+//  VOID
+//  );
+ASM_FUNC(ArmGicV3GetControlRegister)
+        mrs     x0, ICC_CTLR_EL1
+        ret
+
+//VOID
+//ArmGicV3SetControlRegister(
+//  IN UINTN          Value
+//  );
+ASM_FUNC(ArmGicV3SetControlRegister)
+        msr     ICC_CTLR_EL1, x0
+        ret

ArmPkg/Drivers/ArmGicDxe/GicV3/Arm/ArmGicV3.S

@@ -78,3 +78,19 @@ ASM_FUNC(ArmGicV3SetPriorityMask)
 ASM_FUNC(ArmGicV3SetBinaryPointer)
         mcr     p15, 0, r0, c12, c12, 3 //ICC_BPR1
         bx      lr
+
+//UINTN
+//ArmGicV3GetControlRegister(
+//  VOID
+//  );
+ASM_FUNC(ArmGicV3GetControlRegister)
+        mrc     p15, 0, r0, c12, c12, 4 //ICC_CTLR
+        bx      lr
+
+//VOID
+//ArmGicV3SetControlRegister(
+//  IN UINTN          Value
+//  );
+ASM_FUNC(ArmGicV3SetControlRegister)
+        mcr     p15, 0, r0, c12, c12, 4 //ICC_CTLR
+        bx      lr

ArmPkg/Drivers/ArmGicDxe/GicV3/ArmGicV3Dxe.c

@@ -704,6 +704,11 @@ GicV3DxeInitialize (
   // Set priority mask reg to 0xff to allow all priorities through
   ArmGicV3SetPriorityMask (0xff);
 
+  // Use combined priority drop and deactivate (EOImode == 0)
+  RegValue  = ArmGicV3GetControlRegister ();
+  RegValue &= ~(UINT64)ICC_CTLR_EOImode;
+  ArmGicV3SetControlRegister (RegValue);
+
   // Enable gic cpu interface
   ArmGicV3EnableInterruptInterface ();
 

ArmPkg/Include/Library/ArmGicLib.h

@@ -118,7 +118,8 @@
 
 // GIC revision 3 specific declarations
 
-#define ICC_SRE_EL2_SRE  (1 << 0)
+#define ICC_SRE_EL2_SRE   (1 << 0)
+#define ICC_CTLR_EOImode  (1 << 1)
 
 #define ARM_GICD_IROUTER_IRM  BIT31