Re: [edk2-devel] [PATCH 1/2] Mde Pkg: Support for MPAM ACPI Table

["Andrew Fish" <afish@apple.com>]

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> On Aug 19, 2022, at 1:26 AM, Rohit Mathew <rohit.mathew@arm.com> wrote:
> 
> Hi Swatisri,
> 
> Thanks for the patch. Please find my comments inline marked [Rohit] -
> 
>> -----Original Message-----
>> From: devel@edk2.groups.io <mailto:devel@edk2.groups.io> <devel@edk2.groups.io <mailto:devel@edk2.groups.io>> On Behalf Of Name
>> via groups.io <http://groups.io/>
>> Sent: 16 August 2022 21:18
>> To: devel@edk2.groups.io <mailto:devel@edk2.groups.io>; Sami Mujawar <Sami.Mujawar@arm.com <mailto:Sami.Mujawar@arm.com>>;
>> Alexei Fedorov <Alexei.Fedorov@arm.com <mailto:Alexei.Fedorov@arm.com>>; michael.d.kinney@intel.com <mailto:michael.d.kinney@intel.com>;
>> gaoliming@byosoft.com.cn <mailto:gaoliming@byosoft.com.cn>; zhiguang.liu@intel.com <mailto:zhiguang.liu@intel.com>
>> Cc: Swatisri Kantamsetti <swatisrik@nvidia.com <mailto:swatisrik@nvidia.com>>
>> Subject: [edk2-devel] [PATCH 1/2] Mde Pkg: Support for MPAM ACPI Table
>> 
>> From: Swatisri Kantamsetti <swatisrik@nvidia.com>
>> 
>> Added MPAM table header, MSC and Resource Node info structures
>> 
>> Signed-off-by: Swatisri Kantamsetti <swatisrik@nvidia.com>
>> ---
>> MdePkg/Include/IndustryStandard/Acpi64.h |  5 ++
>> MdePkg/Include/IndustryStandard/Mpam.h   | 69
>> ++++++++++++++++++++++++
>> 2 files changed, 74 insertions(+)
>> create mode 100644 MdePkg/Include/IndustryStandard/Mpam.h
>> 
>> diff --git a/MdePkg/Include/IndustryStandard/Acpi64.h
>> b/MdePkg/Include/IndustryStandard/Acpi64.h
>> index fe5ebfac2b..e54f631186 100644
>> --- a/MdePkg/Include/IndustryStandard/Acpi64.h
>> +++ b/MdePkg/Include/IndustryStandard/Acpi64.h
>> @@ -2952,6 +2952,11 @@ typedef struct {
>> ///
>> #define
>> EFI_ACPI_6_4_PROCESSOR_PROPERTIES_TOPOLOGY_TABLE_STRUCTURE_SI
>> GNATURE  SIGNATURE_32('P', 'P', 'T', 'T')
>> 
>> +///
>> +/// "MPAM" Memory System Resource Partitioning And Monitoring Table
>> ///
>> +#define
>> +EFI_ACPI_6_4_MEMORY_SYSTEM_RESOURCE_PARTITIONING_MONITORI
>> NG_TABLE_STRUC
>> +TURE_SIGNATURE  SIGNATURE_32('M', 'P', 'A', 'M')
>> +
>> ///
>> /// "PSDT" Persistent System Description Table  /// diff --git
>> a/MdePkg/Include/IndustryStandard/Mpam.h
>> b/MdePkg/Include/IndustryStandard/Mpam.h
>> new file mode 100644
>> index 0000000000..e0f75f0114
>> --- /dev/null
>> +++ b/MdePkg/Include/IndustryStandard/Mpam.h
>> @@ -0,0 +1,69 @@
>> +/** @file
>> +  ACPI Memory System Resource Partitioning And Monitoring (MPAM)
>> +  as specified in ARM spec DEN0065
>> +
>> +  Copyright (c) 2022, NVIDIA CORPORATION. All rights reserved.
>> +  Copyright (c) 2022, ARM Limited. All rights reserved.
>> +  SPDX-License-Identifier: BSD-2-Clause-Patent **/
>> +
>> +#ifndef _MPAM_H_
>> +#define _MPAM_H_
>> +
>> +#pragma pack(1)
>> +
>> +///
>> +/// Memory System Resource Partitioning and Monitoring Table (MPAM)
>> ///
>> +typedef struct {
>> +  EFI_ACPI_DESCRIPTION_HEADER    Header;
>> +  UINT32                         NumNodes;
>> +  UINT32                         NodeOffset;
>> +  UINT32                         Reserved;
>> +}
>> +EFI_ACPI_6_4_MEMORY_SYSTEM_RESOURCE_PARTITIONING_MONITORI
>> NG_TABLE_HEADE
>> +R;
> 
> [Rohit] Shouldn't the header be followed by MSC node body type as defined in MPAM ACPI 1.0, section 2, table 3 - The MPAM table and section 2.1, table 4 - MSC Node body?
> 
>> +
>> +///
>> +/// MPAM Revision (as defined in ACPI 6.4 spec.) /// #define
>> +EFI_ACPI_6_4_MEMORY_SYSTEM_RESOURCE_PARTITIONING_MONITORI
>> NG_TABLE_REVIS
>> +ION  0x01
>> +
>> +///
>> +/// Memory System Controller Node Structure ///
>> +
>> +typedef struct {
>> +  UINT16    Length;
>> +  UINT16    Reserved;
>> +  UINT32    Identifier;
>> +  UINT64    BaseAddress;
>> +  UINT32    MmioSize;
>> +  UINT32    OverflowInterrupt;
>> +  UINT32    OverflowInterruptFlags;
> 
> [Rohit] Would it be better to have a type (possibly bitfield struct) instead of a plain UINT32 for Flags? (MPAM ACPI 1.0, section 2.1.1, table 5 - Interrupt flags)
> 

Probably better NOT to use bitfields in APIs that are produced and consumed by different worlds. While the the UEFI does speak to the bit order of or a bitfield the rules around packing of bitfields is compiler defined.

I just saw a bug last week with bitfield compatibility that was introduced by clang fixing its -mms-bitfields implementation. The GCC rules for packing bitfields is different than VC++ so that is why the compiler flag -mms-bitfields exists in the 1st place . A clang -mms-bitfields bug  got fixed and it broke the code as the extra padding required by VC++ got added to the bitfield. 

Thanks,

Andrew Fish

>> +  UINT32    Reserved1;
>> +  UINT32    OverflowInterruptAff;
>> +  UINT32    ErrorInterrupt;
>> +  UINT32    ErrorInterruptFlags;
> 
> [Rohit ] Same comment as before above.
> 
>> +  UINT32    Reserved2;
>> +  UINT32    ErrorInterruptAff;
>> +  UINT32    MaxNRdyUsec;
>> +  UINT64    LinkedDeviceHwId;
>> +  UINT32    LinkedDeviceInstanceHwId;
>> +  UINT32    NumResourceNodes;
>> +} EFI_ACPI_6_4_MPAM_MSC_NODE;
>> +
>> +///
>> +/// Resource Node Structure
>> +///
>> +
>> +typedef struct {
>> +  UINT32    Identifier;
>> +  UINT8     RisIndex;
>> +  UINT16    Reserved1;
>> +  UINT8     LocatorType;
>> +  UINT64    Locator;
> 
> [Rohit ] Shouldn't " Locator " field be 12 bytes in size, possibly a separate type? (MPAM ACPI 1.0, section 2.2, table 7 - Resource node and section 2.3.2 table 10 - locator descriptor)
> 
>> +  UINT32    NumFuncDep;
>> +} EFI_ACPI_6_4_MPAM_RESOURCE_NODE;
> 
> [Rohit] Since "NumFuncDep" field is part of EFI_ACPI_6_4_MPAM_RESOURCE_NODE type and this could be non-zero, should we also need the type for functional dependency descriptors? (MPAM ACPI 1.0, section 2.2.1, table 8 - Functional dependency descriptor)
> 
> [Rohit] Also, could some of the commonly used macros be added to this header, please? (location types, MPAM interrupt mode, interrupt types, affinity type, etc)
> 
>> +
>> +#pragma pack()
>> +
>> +#endif
>> --
>> 2.17.1
>> 
>> 
>> 
>> 
>> 
> 
> Regards,
> Rohit
> 
> 
> 
> 


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