Re: [edk2-devel] [PATCH v2 2/2] ShellPkg/Acpiview: Adds ACPI WSMT Table parse

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

Hello Abdul,

On 3/8/24 08:22, Abdul Lateef Attar wrote:
> From: Abdul Lateef Attar <AbdulLateef.Attar@amd.com>
> 
> Adds WSMT parse to the UefiShellAcpiViewCommandLib library.
> 
> Cc: Zhichao Gao <zhichao.gao@intel.com>
> Cc: Pierre Gondois  <pierre.gondois@arm.com>
> Signed-off-by: Abdul Lateef Attar <AbdulLateef.Attar@amd.com>
> Reviewed-by: Pierre Gondois  <pierre.gondois@arm.com>
> ---
>   .../UefiShellAcpiViewCommandLib/AcpiParser.h  |  17 ++
>   .../Parsers/Wsmt/WsmtParser.c                 | 147 ++++++++++++++++++
>   .../UefiShellAcpiViewCommandLib.c             |   1 +
>   .../UefiShellAcpiViewCommandLib.inf           |   1 +
>   4 files changed, 166 insertions(+)
>   create mode 100644 ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Wsmt/WsmtParser.c
> 
> diff --git a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h
> index ba3364f2c2..6468fe5d8c 100644
> --- a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h
> +++ b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h
> @@ -985,6 +985,23 @@ ParseAcpiSsdt (
>     IN UINT8    AcpiTableRevision
>     );
>   
> +/**
> +  This function parses the ACPI WSMT table.
> +
> +  @param [in] Trace              If TRUE, trace the ACPI fields.
> +  @param [in] Ptr                Pointer to the start of the buffer.
> +  @param [in] AcpiTableLength    Length of the ACPI table.
> +  @param [in] AcpiTableRevision  Revision of the ACPI table.
> +**/
> +VOID
> +EFIAPI
> +ParseAcpiWsmt (
> +  IN BOOLEAN  Trace,
> +  IN UINT8    *Ptr,
> +  IN UINT32   AcpiTableLength,
> +  IN UINT8    AcpiTableRevision
> +  );
> +
>   /**
>     This function parses the ACPI XSDT table
>     and optionally traces the ACPI table fields.
> diff --git a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Wsmt/WsmtParser.c b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Wsmt/WsmtParser.c
> new file mode 100644
> index 0000000000..3c7252b0bf
> --- /dev/null
> +++ b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Wsmt/WsmtParser.c
> @@ -0,0 +1,147 @@
> +/** @file
> +  WSMT table parser
> +
> +  Copyright (C) 2024 Advanced Micro Devices, Inc. All rights reserved.
> +  SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +  @par Reference(s):
> +    - Windows SMM Security Mitigation Table spec, version 1.0
> +**/
> +
> +#include <Library/UefiLib.h>
> +#include <IndustryStandard/WindowsSmmSecurityMitigationTable.h>
> +#include "AcpiParser.h"
> +
> +STATIC ACPI_DESCRIPTION_HEADER_INFO  AcpiHdrInfo;
> +
> +/**
> +  This function validates the WSMT Protection flag.
> +
> +  @param [in] Ptr  Pointer to the start of the buffer.
> +  @param [in] Context Pointer to context specific information e.g. this
> +                      could be a pointer to the ACPI table header.
> +
> +**/
> +STATIC
> +VOID
> +EFIAPI
> +ValidateWsmtProtectionFlag (
> +  IN UINT8  *Ptr,
> +  IN VOID   *Context
> +  )
> +{
> +  UINT32  ProtectionFlag;
> +
> +  ProtectionFlag = *(UINT32 *)Ptr;
> +
> +  if ((ProtectionFlag & EFI_WSMT_PROTECTION_FLAGS_COMM_BUFFER_NESTED_PTR_PROTECTION) \
> +      == EFI_WSMT_PROTECTION_FLAGS_COMM_BUFFER_NESTED_PTR_PROTECTION)
> +  {
> +    if ((ProtectionFlag & EFI_WSMT_PROTECTION_FLAGS_FIXED_COMM_BUFFERS) \
> +        != EFI_WSMT_PROTECTION_FLAGS_FIXED_COMM_BUFFERS)
> +    {
> +      IncrementErrorCount ();
> +      Print (L"ERROR: COMM_BUFFER_NESTED_PTR_PROTECTION is set but FIXED_COMM_BUFFERS is not set.\n");
> +    }
> +  }
> +}
> +
> +/**
> +  This function validates the reserved bits in the WSMT Protection flag.
> +
> +  @param [in] Ptr  Pointer to the start of the buffer.
> +  @param [in] Context Pointer to context specific information e.g. this
> +                      could be a pointer to the ACPI table header.
> +**/
> +STATIC
> +VOID
> +EFIAPI
> +ValidateReserved (
> +  IN UINT8  *Ptr,
> +  IN VOID   *Context
> +  )
> +{
> +  UINT32  ProtectionFlag;
> +
> +  ProtectionFlag = *(UINT32 *)Ptr;
> +
> +  if ((ProtectionFlag & 0xFFFFFFF8) != 0) {
> +    IncrementErrorCount ();
> +    Print (L"ERROR: Reserved bits are not zero.\n");
> +  }
> +}
> +
> +/**
> +  An ACPI_PARSER array describing the WSMT Protection flag .
> +**/
> +STATIC CONST ACPI_PARSER  WsmtProtectionFlagParser[] = {
> +  { L"FIXED_COMM_BUFFERS ",                1,  0, L"0x%x", NULL, NULL, NULL,             NULL },
> +  { L"COMM_BUFFER_NESTED_PTR_PROTECTION ", 1,  1, L"0x%x", NULL, NULL, NULL,             NULL },
> +  { L"SYSTEM_RESOURCE_PROTECTION ",        1,  2, L"0x%x", NULL, NULL, NULL,             NULL },
> +  { L"Reserved ",                          29, 3, L"0x%x", NULL, NULL, ValidateReserved, NULL },

I think we misunderstood each other here.
We should check that if COMM_BUFFER_NESTED_PTR_PROTECTION,
then FIXED_COMM_BUFFERS is also set.

So I think we need to:
- store the value of FIXED_COMM_BUFFERS (cf. ACPI_PARSER::ItemPtr in other parsers)
- add a validate to COMM_BUFFER_NESTED_PTR_PROTECTION to check the above

I don't think it is necessary to check the reserved bits,

Regards,
Pierre


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