Re: [PATCH 4/5] UefiCpuPkg: Explain relationship between several SMM PCDs

["Dong, Eric" <eric.dong@intel.com>]

Reviewed-by: Eric Dong <eric.dong@intel.com>

> -----Original Message-----
> From: Ni, Ray
> Sent: Monday, August 26, 2019 6:45 AM
> To: devel@edk2.groups.io
> Cc: Dong, Eric <eric.dong@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>;
> Laszlo Ersek <lersek@redhat.com>
> Subject: [PATCH 4/5] UefiCpuPkg: Explain relationship between several SMM
> PCDs
> 
> There are three PCDs that may impact the behavior of each other in SMM
> environment:
>   PcdCpuSmmProfileEnable
>   PcdHeapGuardPropertyMask in MdeModulePkg
>   PcdCpuSmmRestrictedMemoryAccess
> 
> The patch updates the comments in DEC file to document it.
> 
> Signed-off-by: Ray Ni <ray.ni@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> ---
>  UefiCpuPkg/UefiCpuPkg.dec | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/UefiCpuPkg/UefiCpuPkg.dec b/UefiCpuPkg/UefiCpuPkg.dec index
> 83acd33612..9a03bdd716 100644
> --- a/UefiCpuPkg/UefiCpuPkg.dec
> +++ b/UefiCpuPkg/UefiCpuPkg.dec
> @@ -81,7 +81,8 @@ [Ppis]
>  [PcdsFeatureFlag]
>    ## Indicates if SMM Profile will be enabled.
>    #  If enabled, instruction executions in and data accesses to memory outside
> of SMRAM will be logged.
> -  #  It could not be enabled at the same time with SMM static page table
> feature (PcdCpuSmmStaticPageTable).
> +  #  In X64 build, it could not be enabled when
> PcdCpuSmmRestrictedMemoryAccess is TRUE.
> +  #  In IA32 build, the page table memory is not marked as read-only when it is
> enabled.
>    #  This PCD is only for validation purpose. It should be set to false in
> production.<BR><BR>
>    #   TRUE  - SMM Profile will be enabled.<BR>
>    #   FALSE - SMM Profile will be disabled.<BR>
> @@ -285,6 +286,11 @@ [PcdsFixedAtBuild.X64, PcdsPatchableInModule.X64,
> PcdsDynamic.X64, PcdsDynamicEx
>    #  The PCD value is considered as constantly TRUE in IA32 platforms.
>    #  When the PCD value is TRUE, page table is initialized to cover all memory
> spaces
>    #  and the memory occupied by page table is protected by page table itself as
> read-only.
> +  #  In X64 build, it cannot be enabled at the same time with SMM profile
> feature (PcdCpuSmmProfileEnable).
> +  #  In X64 build, it could not be enabled also at the same time with
> + heap guard feature for SMM  #  (PcdHeapGuardPropertyMask in
> MdeModulePkg).
> +  #  In IA32 build, page table memory is not marked as read-only when
> + either SMM profile feature (PcdCpuSmmProfileEnable)  #  or heap guard
> feature for SMM (PcdHeapGuardPropertyMask in MdeModulePkg) is enabled.
>    #   TRUE  - Access to non-SMRAM memory is restricted to reserved, runtime
> and ACPI NVS type after SmmReadyToLock.<BR>
>    #   FALSE - Access to any type of non-SMRAM memory after
> SmmReadyToLock is allowed.<BR>
>    # @Prompt Access to non-SMRAM memory is restricted to reserved, runtime
> and ACPI NVS type after SmmReadyToLock.
> --
> 2.21.0.windows.1