ArmPkg/Gic: force GIC driver to run before CPU arch protocol driver

Currently, the GIC driver has a static dependency on the CPU arch protocol
driver, so it can register its IRQ handler at init time. This means there
is a window between dispatch of the CPU driver and dispatch of the GIC
driver where any unexpected GIC state may trigger an interrupt which we
are not set up to handle yet. Note that this is even the case if we enter
UEFI with interrupts disabled at the CPU, given that any TPL manipulation
involving TPL_HIGH_LEVEL will unconditionally enable IRQs at the CPU side
regardless of whether they were enabled to begin with (but only as soon as
the CPU arch protocol is actually installed)

So let's reorder the GIC driver with the CPU driver, and let it run its
initialization that puts the GIC into a known state before enabling
interrupts. Move its installation of its IRQ handler to a protocol notify
callback on the CPU arch protocol so that it runs as soon as it becomes
available.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Tested-by: Marc Zyngier <marc.zyngier@arm.com>

ArmPkg/ArmPkg.dec

@@ -48,6 +48,8 @@
   # Include/Guid/ArmMpCoreInfo.h
   gArmMpCoreInfoGuid = { 0xa4ee0728, 0xe5d7, 0x4ac5,  {0xb2, 0x1e, 0x65, 0x8e, 0xd8, 0x57, 0xe8, 0x34} }
 
+  gArmGicDxeFileGuid = { 0xde371f7c, 0xdec4, 0x4d21, { 0xad, 0xf1, 0x59, 0x3a, 0xbc, 0xc1, 0x58, 0x82 } }
+
 [Ppis]
   ## Include/Ppi/ArmMpCoreInfo.h
   gArmMpCoreInfoPpiGuid = { 0x6847cc74, 0xe9ec, 0x4f8f, {0xa2, 0x9d, 0xab, 0x44, 0xe7, 0x54, 0xa8, 0xfc} }

ArmPkg/Drivers/ArmGic/ArmGicCommonDxe.c

@@ -121,6 +121,44 @@ RegisterInterruptSource (
   }
 }
 
+STATIC VOID *mCpuArchProtocolNotifyEventRegistration;
+
+STATIC
+VOID
+EFIAPI
+CpuArchEventProtocolNotify (
+  IN  EFI_EVENT       Event,
+  IN  VOID            *Context
+  )
+{
+  EFI_CPU_ARCH_PROTOCOL   *Cpu;
+  EFI_STATUS              Status;
+
+  // Get the CPU protocol that this driver requires.
+  Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **)&Cpu);
+  if (EFI_ERROR (Status)) {
+    return;
+  }
+
+  // Unregister the default exception handler.
+  Status = Cpu->RegisterInterruptHandler (Cpu, ARM_ARCH_EXCEPTION_IRQ, NULL);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_ERROR, "%a: Cpu->RegisterInterruptHandler() - %r\n",
+      __FUNCTION__, Status));
+    return;
+  }
+
+  // Register to receive interrupts
+  Status = Cpu->RegisterInterruptHandler (Cpu, ARM_ARCH_EXCEPTION_IRQ,
+                  Context);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_ERROR, "%a: Cpu->RegisterInterruptHandler() - %r\n",
+      __FUNCTION__, Status));
+  }
+
+  gBS->CloseEvent (Event);
+}
+
 EFI_STATUS
 InstallAndRegisterInterruptService (
   IN EFI_HARDWARE_INTERRUPT_PROTOCOL   *InterruptProtocol,
@@ -130,7 +168,6 @@ InstallAndRegisterInterruptService (
   )
 {
   EFI_STATUS               Status;
-  EFI_CPU_ARCH_PROTOCOL   *Cpu;
   CONST UINTN              RihArraySize =
     (sizeof(HARDWARE_INTERRUPT_HANDLER) * mGicNumInterrupts);
 
@@ -152,27 +189,15 @@ InstallAndRegisterInterruptService (
     return Status;
   }
 
-  // Get the CPU protocol that this driver requires.
-  Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **)&Cpu);
-  if (EFI_ERROR (Status)) {
-    return Status;
-  }
-
-  // Unregister the default exception handler.
-  Status = Cpu->RegisterInterruptHandler (Cpu, ARM_ARCH_EXCEPTION_IRQ, NULL);
-  if (EFI_ERROR (Status)) {
-    return Status;
-  }
-
-  // Register to receive interrupts
-  Status = Cpu->RegisterInterruptHandler (
-                  Cpu,
-                  ARM_ARCH_EXCEPTION_IRQ,
-                  InterruptHandler
-                  );
-  if (EFI_ERROR (Status)) {
-    return Status;
-  }
+  //
+  // Install the interrupt handler as soon as the CPU arch protocol appears.
+  //
+  EfiCreateProtocolNotifyEvent (
+    &gEfiCpuArchProtocolGuid,
+    TPL_CALLBACK,
+    CpuArchEventProtocolNotify,
+    InterruptHandler,
+    &mCpuArchProtocolNotifyEventRegistration);
 
   // Register for an ExitBootServicesEvent
   Status = gBS->CreateEvent (

ArmPkg/Drivers/ArmGic/ArmGicDxe.h

@@ -21,6 +21,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 #include <Library/IoLib.h>
 #include <Library/MemoryAllocationLib.h>
 #include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
 
 #include <Protocol/Cpu.h>
 #include <Protocol/HardwareInterrupt.h>

ArmPkg/Drivers/ArmGic/ArmGicDxe.inf

@@ -16,7 +16,7 @@
 [Defines]
   INF_VERSION                    = 0x00010005
   BASE_NAME                      = ArmGicDxe
-  FILE_GUID                      = DE371F7C-DEC4-4D21-ADF1-593ABCC15882
+  FILE_GUID                      = DE371F7C-DEC4-4D21-ADF1-593ABCC15882 # gArmGicDxeFileGuid
   MODULE_TYPE                    = DXE_DRIVER
   VERSION_STRING                 = 1.0
 
@@ -45,6 +45,7 @@
   UefiDriverEntryPoint
   IoLib
   PcdLib
+  UefiLib
 
 [Protocols]
   gHardwareInterruptProtocolGuid
@@ -58,4 +59,4 @@
   gArmTokenSpaceGuid.PcdArmGicV3WithV2Legacy
 
 [Depex]
-  gEfiCpuArchProtocolGuid
+  TRUE

ArmPkg/Drivers/CpuDxe/CpuDxe.inf

@@ -74,4 +74,4 @@
   gArmTokenSpaceGuid.PcdDebuggerExceptionSupport
 
 [Depex]
-  TRUE
+  AFTER gArmGicDxeFileGuid