Re: [PATCH edk2-platforms v1 1/1] Platform/Arm: Disable memmap platform timers for JunoR0

["PierreGondois" <pierre.gondois@arm.com>]

Reviewed-by: Pierre Gondois <pierre.gondois@arm.com>

On 6/16/23 14:40, Sami Mujawar wrote:
> Juno includes a system-level wakeup timer which is an implementation
> of the ARM Generic Timer architecture.
> The CNTCTL frame contains some registers that are accessible using a
> Non-Secure access. Juno R0 incorrectly limits these accesses to Secure
> access only. This issue is documented in the Juno Errata
> 832219: APB port security breaks SBSA compliance
> https://developer.arm.com/documentation/epm008857/latest
> 
> This results in a crash when the OS tries to access these registers.
> Therefore, disable memory mapped platform timers for Juno R0.
> 
> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
> Cc: Thomas Abraham <thomas.abraham@arm.com>
> Cc: Sudeep Holla <Sudeep.Holla@arm.com>
> 
> Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
> Reported-by: Sudeep Holla <Sudeep.Holla@arm.com>
> ---
> The changes can be seen at: https://github.com/samimujawar/edk2-platforms/tree/1496_junor0_disable_memmap_plat_timers_v1
> 
>   Platform/ARM/JunoPkg/ConfigurationManager/ConfigurationManagerDxe/ConfigurationManager.c | 48 ++++++++++++--------
>   1 file changed, 30 insertions(+), 18 deletions(-)
> 
> diff --git a/Platform/ARM/JunoPkg/ConfigurationManager/ConfigurationManagerDxe/ConfigurationManager.c b/Platform/ARM/JunoPkg/ConfigurationManager/ConfigurationManagerDxe/ConfigurationManager.c
> index 48f0fd370f073c8fed1a649d8c4ab28b062a8290..91f035480dcfe81e93febfac2ef703d6c77737f1 100644
> --- a/Platform/ARM/JunoPkg/ConfigurationManager/ConfigurationManagerDxe/ConfigurationManager.c
> +++ b/Platform/ARM/JunoPkg/ConfigurationManager/ConfigurationManagerDxe/ConfigurationManager.c
> @@ -1,7 +1,7 @@
>   /** @file
>     Configuration Manager Dxe
>   
> -  Copyright (c) 2017 - 2022, Arm Limited. All rights reserved.<BR>
> +  Copyright (c) 2017 - 2023, Arm Limited. All rights reserved.<BR>
>   
>     SPDX-License-Identifier: BSD-2-Clause-Patent
>   
> @@ -1380,26 +1380,38 @@ GetArmNameSpaceObject (
>         break;
>   
>       case EArmObjPlatformGTBlockInfo:
> -      Status = HandleCmObject (
> -                 CmObjectId,
> -                 PlatformRepo->GTBlockInfo,
> -                 sizeof (PlatformRepo->GTBlockInfo),
> -                 ARRAY_SIZE (PlatformRepo->GTBlockInfo),
> -                 CmObject
> -                 );
> +      if (PlatformRepo->JunoRevision == JUNO_REVISION_R0) {
> +        // Disable Memory Mapped Platform Timers for Juno R0
> +        // due to Juno Erratum 832219.
> +        Status = EFI_NOT_FOUND;
> +      } else {
> +        Status = HandleCmObject (
> +                   CmObjectId,
> +                   PlatformRepo->GTBlockInfo,
> +                   sizeof (PlatformRepo->GTBlockInfo),
> +                   ARRAY_SIZE (PlatformRepo->GTBlockInfo),
> +                   CmObject
> +                  );
> +      }
>         break;
>   
>       case EArmObjGTBlockTimerFrameInfo:
> -      Status = HandleCmObjectRefByToken (
> -                 This,
> -                 CmObjectId,
> -                 PlatformRepo->GTBlock0TimerInfo,
> -                 sizeof (PlatformRepo->GTBlock0TimerInfo),
> -                 ARRAY_SIZE (PlatformRepo->GTBlock0TimerInfo),
> -                 Token,
> -                 GetGTBlockTimerFrameInfo,
> -                 CmObject
> -                 );
> +      if (PlatformRepo->JunoRevision == JUNO_REVISION_R0) {
> +        // Disable Memory Mapped Platform Timers for Juno R0
> +        // due to Juno Erratum 832219.
> +        Status = EFI_NOT_FOUND;
> +      } else {
> +        Status = HandleCmObjectRefByToken (
> +                   This,
> +                   CmObjectId,
> +                   PlatformRepo->GTBlock0TimerInfo,
> +                   sizeof (PlatformRepo->GTBlock0TimerInfo),
> +                   ARRAY_SIZE (PlatformRepo->GTBlock0TimerInfo),
> +                   Token,
> +                   GetGTBlockTimerFrameInfo,
> +                   CmObject
> +                   );
> +      }
>         break;
>   
>       case EArmObjGicCInfo: