Re: [PATCH v5 0/8] Add Variable Flash Info HOB

["Ard Biesheuvel" <ardb@kernel.org>]

On Tue, 26 Apr 2022 at 03:29, <mikuback@linux.microsoft.com> wrote:
>
> From: Michael Kubacki <michael.kubacki@microsoft.com>
>
> REF:https://bugzilla.tianocore.org/show_bug.cgi?id=3479
>
> Platforms: This series introduces a new library class called
> VariableFlashInfoLib. Platforms using the variable modules will
> need to specify these library classes. See the patches at the
> end of this series for examples of the change needed in the
> platform DSC file. I have attempted to update all open-source
> platforms in edk2 and edk2-platforms in this series and
> https://edk2.groups.io/g/devel/message/89148.
>

I will make the same remark here as I made in response to the
edk2-platforms series:

Could we please consider introducing a way to define the default
resolution of a library class? That way, all this churn and
unnecessary breakage would not be necessary, as defining a resolution
would only be necessary when deviating from the default. In fact, we
might be able to clean up some .DSCs considerably by defining defaults
for library classes that only have one (or very few) implementations.


> The UEFI variable drivers such as VariableRuntimeDxe, VariableSmm,
> VariableStandaloneMm, etc. (and their dependent protocol/library
> stack), typically acquire UEFI variable store flash information
> with PCDs declared in MdeModulePkg.
>
> For example:
> [Pcd]
>   gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableBase
>   gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableBase64
>   gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableSize
>
> These PCDs work as-is in the StandaloneMm driver if they are not
> dynamic such as Dynamic or DynamicEx because PCD services are not
> readily available in the Standalone MM environment. Platforms that
> use Standalone MM today, must define these PCDs as FixedAtBuild in
> their platform build. However, the PCDs do allow platforms to treat
> the PCDs as Dynamic/DynamicEx and being able to support that is
> currently a gap for Standalone MM.
>
> This patch series introduces a HOB that can be produced by the
> platform to provide the same information. The HOB list is
> available to Standalone MM.
>
> The PCD declarations are left as-is in MdeModulePkg for backward
> compatibility. This means unless a platform wants to use the HOB,
> their code will continue to work with no change (they do not need
> to produce the HOB). Only if the HOB is found, is its value used
> instead of the PCDs.
>
> Due to the large number of consumers of this information, access
> to the base address and size values is abstracted in a new library
> class (as requested in the v1 series) called VariableFlashInfoLib.
>
> The API of VariableFlashInfoLib does not bind the underlying data
> structure to the information returned to library users to allow
> flexibility in the library implementation in the future.
>
> V5 changes.
> 1. Made GetVariableFlashInfoFromHob() in BaseVariableFlashInfoLib.c
>    STATIC.
> 2. Added a section in commit v5 [3/8] to explicitly state that the
>    commit introduces a dependency that requires a change in platform
>    build.  Please see patches v5 [5/8] - v5 [8/8] for examples of
>    how to integrate this change (add VariableFlashInfoLib library
>    to DSC file).
>
> V4 changes:
> 1. Add a UINT32 "Reserved" field to VARIABLE_FLASH_INFO.
> 2. Add a descriptive comment to VariableFlashInfo.h to explain
>    HOB usage.
>
> V3 changes:
> 1. To better clarify usage, renamed the members
>    "NvStorageBaseAddress" and "NvStorageLength" in
>    "VARIABLE_FLASH_INFO" to "NvVariableBaseAddress" and
>    "NvVariableLength".
> 2. Added description comments to the fields in "VARIABLE_FLASH_INFO".
>
> V2 changes:
> 1. Abstracted flash info data access with VariableFlashInfoLib.
> 2. Updated package builds in the repo that build the variable and
>    FTW drivers to include VariableFlashInfoLib.
> 3. Removed a redundant variable assignment in VariableSmm.c.
> 4. Updated comments in FtwMisc.c and FaultTolerantWritePei.c to
>    indicate driver assumption is UINTN (not UINT32)
> 5. Added a version field to the VARIABLE_FLASH_INFO structure.
>
> Cc: Abner Chang <abner.chang@hpe.com>
> Cc: Andrew Fish <afish@apple.com>
> Cc: Anthony Perard <anthony.perard@citrix.com>
> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
> Cc: Benjamin You <benjamin.you@intel.com>
> Cc: Brijesh Singh <brijesh.singh@amd.com>
> Cc: Erdem Aktas <erdemaktas@google.com>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Guo Dong <guo.dong@intel.com>
> Cc: Hao A Wu <hao.a.wu@intel.com>
> Cc: James Bottomley <jejb@linux.ibm.com>
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Julien Grall <julien@xen.org>
> Cc: Leif Lindholm <quic_llindhol@quicinc.com>
> Cc: Liming Gao <gaoliming@byosoft.com.cn>
> Cc: Maurice Ma <maurice.ma@intel.com>
> Cc: Min Xu <min.m.xu@intel.com>
> Cc: Nickle Wang <nickle.wang@hpe.com>
> Cc: Peter Grehan <grehan@freebsd.org>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Rebecca Cran <rebecca@bsdio.com>
> Cc: Sami Mujawar <sami.mujawar@arm.com>
> Cc: Sean Rhodes <sean@starlabs.systems>
> Cc: Sebastien Boeuf <sebastien.boeuf@intel.com>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
>
> Michael Kubacki (8):
>   MdeModulePkg: Add Variable Flash Info HOB
>   MdeModulePkg/VariableFlashInfoLib: Add initial library
>   MdeModulePkg/Variable: Consume Variable Flash Info
>   MdeModulePkg/FaultTolerantWrite: Consume Variable Flash Info
>   ArmVirtPkg/ArmVirt.dsc.inc: Add VariableFlashInfoLib
>   EmulatorPkg: Add VariableFlashInfoLib
>   OvmfPkg: Add VariableFlashInfoLib
>   UefiPayloadPkg: Add VariableFlashInfoLib
>
>  MdeModulePkg/Library/BaseVariableFlashInfoLib/BaseVariableFlashInfoLib.c        | 179 ++++++++++++++++++++
>  MdeModulePkg/Universal/FaultTolerantWriteDxe/FtwMisc.c                          |  41 +++--
>  MdeModulePkg/Universal/FaultTolerantWriteDxe/UpdateWorkingBlock.c               |   7 +-
>  MdeModulePkg/Universal/FaultTolerantWritePei/FaultTolerantWritePei.c            |  28 +--
>  MdeModulePkg/Universal/Variable/Pei/Variable.c                                  |  14 +-
>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableDxe.c                        |  16 +-
>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableNonVolatile.c                |  14 +-
>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.c                        |  17 +-
>  ArmVirtPkg/ArmVirt.dsc.inc                                                      |   1 +
>  EmulatorPkg/EmulatorPkg.dsc                                                     |   1 +
>  MdeModulePkg/Include/Guid/VariableFlashInfo.h                                   | 111 ++++++++++++
>  MdeModulePkg/Include/Library/VariableFlashInfoLib.h                             |  68 ++++++++
>  MdeModulePkg/Library/BaseVariableFlashInfoLib/BaseVariableFlashInfoLib.inf      |  48 ++++++
>  MdeModulePkg/Library/BaseVariableFlashInfoLib/BaseVariableFlashInfoLib.uni      |  12 ++
>  MdeModulePkg/MdeModulePkg.dec                                                   |   8 +
>  MdeModulePkg/MdeModulePkg.dsc                                                   |   2 +
>  MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWrite.h               |   7 +-
>  MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteDxe.inf          |  10 +-
>  MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.inf          |  10 +-
>  MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteStandaloneMm.inf |  10 +-
>  MdeModulePkg/Universal/FaultTolerantWritePei/FaultTolerantWritePei.inf          |  10 +-
>  MdeModulePkg/Universal/Variable/Pei/Variable.h                                  |   2 +
>  MdeModulePkg/Universal/Variable/Pei/VariablePei.inf                             |   5 +-
>  MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.h                           |   7 +-
>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeDxe.inf               |   5 +-
>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.inf                      |   5 +-
>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableStandaloneMm.inf             |   5 +-
>  OvmfPkg/AmdSev/AmdSevX64.dsc                                                    |   1 +
>  OvmfPkg/Bhyve/BhyveX64.dsc                                                      |   1 +
>  OvmfPkg/CloudHv/CloudHvX64.dsc                                                  |   1 +
>  OvmfPkg/IntelTdx/IntelTdxX64.dsc                                                |   1 +
>  OvmfPkg/Microvm/MicrovmX64.dsc                                                  |   1 +
>  OvmfPkg/OvmfPkgIa32.dsc                                                         |   1 +
>  OvmfPkg/OvmfPkgIa32X64.dsc                                                      |   1 +
>  OvmfPkg/OvmfPkgX64.dsc                                                          |   1 +
>  OvmfPkg/OvmfXen.dsc                                                             |   1 +
>  UefiPayloadPkg/UefiPayloadPkg.dsc                                               |   1 +
>  37 files changed, 559 insertions(+), 94 deletions(-)
>  create mode 100644 MdeModulePkg/Library/BaseVariableFlashInfoLib/BaseVariableFlashInfoLib.c
>  create mode 100644 MdeModulePkg/Include/Guid/VariableFlashInfo.h
>  create mode 100644 MdeModulePkg/Include/Library/VariableFlashInfoLib.h
>  create mode 100644 MdeModulePkg/Library/BaseVariableFlashInfoLib/BaseVariableFlashInfoLib.inf
>  create mode 100644 MdeModulePkg/Library/BaseVariableFlashInfoLib/BaseVariableFlashInfoLib.uni
>
> --
> 2.28.0.windows.1
>