Re: [edk2-devel] [PATCH V2 1/1] MdeModulePkg: Support customized FV Migration Information

["Wang Fan" <fan.wang@intel.com>]

Hi Mike

Thank you for your feedback.

I have updated the patch to v3: https://edk2.groups.io/g/devel/message/110197

Pull Request: https://github.com/tianocore/edk2/pull/4970

Based on V2, this update includes changes:
- Add more descriptions for "gEdkiiToMigrateFvInfoGuid" PPI usages and background, but still keep the name.
- Update "FvOrgBase" to "FvTemporaryRamBase" in EDKII_TO_MIGRATE_FV_INFO.
- Remove flag "FLAGS_SKIP_FV_MIGRATION", since it's not needed.
- Add more descriptions to flag "FLAGS_SKIP_FV_RAW_DATA_COPY".
- Remove the variable MigrateAllFvs to simplify logic.
- Correct "allocate pool" to "allocate pages" to align with descriptions.

For other two questions you are mentioning:

1. For "Should FvOrgBase be a UINT64 or support temp RAM above 4GB?":
I think UINT32 should be enough, all pre-mem FVs are below 4G as far as I know, even we enabled X64 in pre-mem phase. This setting is also aligning with "FvOrgBase" defined in "EDKII_MIGRATED_FV_INFO".
2. For "The call to RemoveFvHobsInTemporaryMemory (Private) was removed":
Since this function will remove all FV hobs for physical addresses, it should be called only when all pre-mem FVs are migrated. In EvacuateTempRam(), when one FV is migrated, ConvertFvHob() will be called for this FV and all its' child FVs, this is enough to ensure already migrated FV hobs are all pointing to addresses on permanent address. 

What do you think?

Best Regards
Fan

-----Original Message-----
From: Kinney, Michael D <michael.d.kinney@intel.com> 
Sent: Tuesday, October 17, 2023 5:00 AM
To: Wang, Fan <fan.wang@intel.com>; devel@edk2.groups.io
Cc: Gao, Liming <gaoliming@byosoft.com.cn>; Jiang, Guomin <guomin.jiang@intel.com>; Bi, Dandan <dandan.bi@intel.com>; Kinney, Michael D <michael.d.kinney@intel.com>
Subject: RE: [PATCH V2 1/1] MdeModulePkg: Support customized FV Migration Information

Hi Fan,

The logic looks functional, but there are some names and descriptions that could be added to help describe this feature and some code changes to make the code easier to understand.

1) The GUID gEdkiiToMigrateFvInfoGuid is hard to understand what
   information it conveys from the name of the GUID variable.
   I know that the intent is that it is a GUID with data that 
   tells the PEI core which FVs in temporary RAM should be 
   migrated to permanent RAM.  And that the use of this information
   is only a performance optimization to not migrate FVs that 
   are not needed after the PEI Core migrates temp RAM to 
   permanent RAM.  The name and description in comments do not
   express all these details.

2) The structure name EDKII_TO_MIGRATE_FV_INFO has the same
   issue as (1).
   a) Should FvOrgBase be a UINT64 or support temp RAM above 4GB?
   b) Since only temp RAM to perm RAM migrations are supported
      the field name "FvOrgBase" should be "FvTemporaryRamBase".


3) The #define for FLAGS_SKIP_FV_MIGRATION should have a comment
   block that describes the meaning of this bit.  What is the 
   meaning when the bit is set and what is the meaning when the
   bit is clear.

4) The #define for FLAGS_SKIP_FV_RAW_DATA_COPY should have a comment
   block that describes the meaning of this bit.  What is the 
   meaning when the bit is set and what is the meaning when the
   bit is clear.

5) Why are there 2 bits?  If an FV is skipped, then that means
   do not copy.  If an FV is not skipped, then that means do
   copy.

6) I think the variable MigrateAllFvs can be removed, and the HOB
   list check can be made for gEdkiiToMigrateFvInfoGuid can be made
   on each FV found in temporary RAM.  This looks like a performance
   optimization that makes the logic harder to understand and it
   is not clear that the performance optimization has any benefit.

7) The call to RemoveFvHobsInTemporaryMemory (Private) was removed.  Why?

8) The comment where memory is allocated for the migrated FV says
   "allocate pool" when PeiServicesAllocatePages() is used.  Please 
   update the comment.

Mike



> -----Original Message-----
> From: Wang, Fan <fan.wang@intel.com>
> Sent: Monday, September 11, 2023 2:52 AM
> To: devel@edk2.groups.io
> Cc: Wang, Fan <fan.wang@intel.com>; Kinney, Michael D 
> <michael.d.kinney@intel.com>; Gao, Liming <gaoliming@byosoft.com.cn>; 
> Jiang, Guomin <guomin.jiang@intel.com>; Bi, Dandan 
> <dandan.bi@intel.com>
> Subject: [PATCH V2 1/1] MdeModulePkg: Support customized FV Migration 
> Information
> 
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4533
> 
> There are use cases which not all FVs need be migrated from TempRam to 
> permanent memory before TempRam tears down. This new guid is 
> introduced to avoid unnecessary FV migration to improve boot 
> performance.
> Platform
> can publish ToMigrateFvInfo hob with this guid to customize FV 
> migration info, and PeiCore will only migrate FVs indicated by this 
> Hob info.
> 
> This is a backwards compatible change, PeiCore will check 
> ToMigrateFvInfo hob before migration. If ToMigrateFvInfo hobs exists, 
> only migrate FVs recorded by hobs. If ToMigrateFvInfo hobs not exists, 
> migrate all FVs to permanent memory.
> 
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Liming Gao <gaoliming@byosoft.com.cn>
> Cc: Guomin Jiang <guomin.jiang@intel.com>
> Cc: Dandan Bi <dandan.bi@intel.com>
> Signed-off-by: Wang Fan <fan.wang@intel.com>
> ---
>  MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c | 82 +++++++++++++-----
> -
>  MdeModulePkg/Core/Pei/PeiMain.inf             |  1 +
>  MdeModulePkg/Include/Guid/MigratedFvInfo.h    | 19 +++++
>  MdeModulePkg/MdeModulePkg.dec                 |  3 +-
>  4 files changed, 79 insertions(+), 26 deletions(-)
> 
> diff --git a/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c
> b/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c
> index 5f32ebb560ae..e84849ec6db1 100644
> --- a/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c
> +++ b/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c
> @@ -1184,7 +1184,11 @@ EvacuateTempRam (
> 
>    PEI_CORE_FV_HANDLE            PeiCoreFvHandle;
>    EFI_PEI_CORE_FV_LOCATION_PPI  *PeiCoreFvLocationPpi;
> +  EDKII_TO_MIGRATE_FV_INFO      *ToMigrateFvInfo;
>    EDKII_MIGRATED_FV_INFO        MigratedFvInfo;
> +  EFI_PEI_HOB_POINTERS          Hob;
> +  BOOLEAN                       MigrateAllFvs;
> +  UINT32                        MigrationFlags;
> 
>    ASSERT (Private->PeiMemoryInstalled);
> 
> @@ -1211,6 +1215,17 @@ EvacuateTempRam (
> 
>    ConvertPeiCorePpiPointers (Private, &PeiCoreFvHandle);
> 
> +  //
> +  // Check if platform defined hobs to indicate which FVs are
> expected to migrate or keep raw data.
> +  // If ToMigrateFvInfo hobs exists, only migrate FVs recorded by
> hobs.
> +  // If ToMigrateFvInfo hobs not exists, migrate all FVs to permanent
> memory.
> +  //
> +  MigrateAllFvs = TRUE;
> +  Hob.Raw       = GetFirstGuidHob (&gEdkiiToMigrateFvInfoGuid);
> +  if (Hob.Raw != NULL) {
> +    MigrateAllFvs = FALSE;
> +  }
> +
>    for (FvIndex = 0; FvIndex < Private->FvCount; FvIndex++) {
>      FvHeader = Private->Fv[FvIndex].FvHeader;
>      ASSERT (FvHeader != NULL);
> @@ -1224,6 +1239,25 @@ EvacuateTempRam (
>            )
>          )
>      {
> +      if (MigrateAllFvs) {
> +        MigrationFlags = 0;
> +      } else {
> +        MigrationFlags = FLAGS_SKIP_FV_MIGRATION |
> FLAGS_SKIP_FV_RAW_DATA_COPY;
> +        Hob.Raw = GetFirstGuidHob (&gEdkiiToMigrateFvInfoGuid);
> +        while (Hob.Raw != NULL) {
> +          ToMigrateFvInfo = GET_GUID_HOB_DATA (Hob);
> +          if (ToMigrateFvInfo->FvOrgBase == (UINT32)(UINTN)FvHeader)
> {
> +            MigrationFlags = ToMigrateFvInfo->MigrationFlags;
> +            break;
> +          }
> +          Hob.Raw = GET_NEXT_HOB (Hob);
> +          Hob.Raw = GetNextGuidHob (&gEdkiiToMigrateFvInfoGuid,
> Hob.Raw);
> +        }
> +      }
> +      if (MigrationFlags & FLAGS_SKIP_FV_MIGRATION) {
> +        continue;
> +      }
> +
>        //
>        // Allocate page to save the rebased PEIMs, the PEIMs will get 
> dispatched later.
>        //
> @@ -1234,18 +1268,7 @@ EvacuateTempRam (
>                    );
>        ASSERT_EFI_ERROR (Status);
>        MigratedFvHeader = (EFI_FIRMWARE_VOLUME_HEADER 
> *)(UINTN)FvHeaderAddress;
> -
> -      //
> -      // Allocate pool to save the raw PEIMs, which is used to keep
> consistent context across
> -      // multiple boot and PCR0 will keep the same no matter if the
> address of allocated page is changed.
> -      //
> -      Status =  PeiServicesAllocatePages (
> -                  EfiBootServicesCode,
> -                  EFI_SIZE_TO_PAGES ((UINTN)FvHeader->FvLength),
> -                  &FvHeaderAddress
> -                  );
> -      ASSERT_EFI_ERROR (Status);
> -      RawDataFvHeader = (EFI_FIRMWARE_VOLUME_HEADER
> *)(UINTN)FvHeaderAddress;
> +      CopyMem (MigratedFvHeader, FvHeader, (UINTN)FvHeader-
> >FvLength);
> 
>        DEBUG ((
>          DEBUG_VERBOSE,
> @@ -1256,18 +1279,29 @@ EvacuateTempRam (
>          ));
> 
>        //
> -      // Copy the context to the rebased pages and raw pages, and
> create hob to save the
> -      // information. The MigratedFvInfo HOB will never be produced
> when
> -      // PcdMigrateTemporaryRamFirmwareVolumes is FALSE, because the
> PCD control the
> -      // feature.
> +      // Copy the context to the raw pages, and create hob to save
> the information. The MigratedFvInfo
> +      // HOB will never be produced when
> PcdMigrateTemporaryRamFirmwareVolumes is FALSE, because the PCD
> +      // controls the feature.
>        //
> -      CopyMem (MigratedFvHeader, FvHeader, (UINTN)FvHeader-
> >FvLength);
> -      CopyMem (RawDataFvHeader, MigratedFvHeader, (UINTN)FvHeader-
> >FvLength);
> -      MigratedFvInfo.FvOrgBase  = (UINT32)(UINTN)FvHeader;
> -      MigratedFvInfo.FvNewBase  = (UINT32)(UINTN)MigratedFvHeader;
> -      MigratedFvInfo.FvDataBase = (UINT32)(UINTN)RawDataFvHeader;
> -      MigratedFvInfo.FvLength   = (UINT32)(UINTN)FvHeader->FvLength;
> -      BuildGuidDataHob (&gEdkiiMigratedFvInfoGuid, &MigratedFvInfo,
> sizeof (MigratedFvInfo));
> +      if ((MigrationFlags & FLAGS_SKIP_FV_RAW_DATA_COPY) !=
> FLAGS_SKIP_FV_RAW_DATA_COPY) {
> +        //
> +        // Allocate pool to save the raw PEIMs, which is used to keep
> consistent context across
> +        // multiple boot and PCR0 will keep the same no matter if the
> address of allocated page is changed.
> +        //
> +        Status =  PeiServicesAllocatePages (
> +                    EfiBootServicesCode,
> +                    EFI_SIZE_TO_PAGES ((UINTN)FvHeader->FvLength),
> +                    &FvHeaderAddress
> +                    );
> +        ASSERT_EFI_ERROR (Status);
> +        RawDataFvHeader = (EFI_FIRMWARE_VOLUME_HEADER
> *)(UINTN)FvHeaderAddress;
> +        CopyMem (RawDataFvHeader, MigratedFvHeader, (UINTN)FvHeader-
> >FvLength);
> +        MigratedFvInfo.FvOrgBase  = (UINT32)(UINTN)FvHeader;
> +        MigratedFvInfo.FvNewBase  = (UINT32)(UINTN)MigratedFvHeader;
> +        MigratedFvInfo.FvDataBase = (UINT32)(UINTN)RawDataFvHeader;
> +        MigratedFvInfo.FvLength   = (UINT32)(UINTN)FvHeader-
> >FvLength;
> +        BuildGuidDataHob (&gEdkiiMigratedFvInfoGuid, &MigratedFvInfo,
> sizeof (MigratedFvInfo));
> +      }
> 
>        //
>        // Migrate any children for this FV now @@ -1330,8 +1364,6 @@ 
> EvacuateTempRam (
>      }
>    }
> 
> -  RemoveFvHobsInTemporaryMemory (Private);
> -
>    return Status;
>  }
> 
> diff --git a/MdeModulePkg/Core/Pei/PeiMain.inf
> b/MdeModulePkg/Core/Pei/PeiMain.inf
> index 0cf357371a16..944b230b0e19 100644
> --- a/MdeModulePkg/Core/Pei/PeiMain.inf
> +++ b/MdeModulePkg/Core/Pei/PeiMain.inf
> @@ -78,6 +78,7 @@
>    gEfiFirmwareFileSystem3Guid
>    gStatusCodeCallbackGuid
>    gEdkiiMigratedFvInfoGuid                      ## SOMETIMES_PRODUCES
> ## HOB
> +  gEdkiiToMigrateFvInfoGuid                     ## SOMETIMES_CONSUMES
> ## HOB
> 
>  [Ppis]
>    gEfiPeiStatusCodePpiGuid                      ## SOMETIMES_CONSUMES
> # PeiReportStatusService is not ready if this PPI doesn't exist diff 
> --git a/MdeModulePkg/Include/Guid/MigratedFvInfo.h
> b/MdeModulePkg/Include/Guid/MigratedFvInfo.h
> index aca2332a0ec6..543cd9ba7ddd 100644
> --- a/MdeModulePkg/Include/Guid/MigratedFvInfo.h
> +++ b/MdeModulePkg/Include/Guid/MigratedFvInfo.h
> @@ -9,6 +9,24 @@ SPDX-License-Identifier: BSD-2-Clause-Patent  #ifndef 
> __EDKII_MIGRATED_FV_INFO_GUID_H__  #define 
> __EDKII_MIGRATED_FV_INFO_GUID_H__
> 
> +#define FLAGS_SKIP_FV_MIGRATION        BIT0
> +#define FLAGS_SKIP_FV_RAW_DATA_COPY    BIT1
> +
> +///
> +/// EDKII_TO_MIGRATE_FV_INFO Hob information should be published by
> platform to indicate
> +/// one FV is expected to migrate to permarnant memory or not before
> TempRam tears down.
> +///
> +typedef struct {
> +  UINT32     FvOrgBase;        // original FV address
> +  //
> +  // Migration Flags:
> +  // Bit0: Indicate to skip FV migration or not
> +  // Bit1: Indicate to skip FV raw data copy or not
> +  // Others: Reserved bits
> +  //
> +  UINT32     MigrationFlags;
> +} EDKII_TO_MIGRATE_FV_INFO;
> +
>  typedef struct {
>    UINT32    FvOrgBase;         // original FV address
>    UINT32    FvNewBase;         // new FV address
> @@ -16,6 +34,7 @@ typedef struct {
>    UINT32    FvLength;          // Fv Length
>  } EDKII_MIGRATED_FV_INFO;
> 
> +extern EFI_GUID  gEdkiiToMigrateFvInfoGuid;
>  extern EFI_GUID  gEdkiiMigratedFvInfoGuid;
> 
>  #endif // #ifndef __EDKII_MIGRATED_FV_INFO_GUID_H__ diff --git 
> a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec index 
> dd182c02fdf6..d6cbcc721a5e 100644
> --- a/MdeModulePkg/MdeModulePkg.dec
> +++ b/MdeModulePkg/MdeModulePkg.dec
> @@ -416,7 +416,8 @@
>    gEdkiiCapsuleOnDiskNameGuid = { 0x98c80a4f, 0xe16b, 0x4d11, { 0x93, 
> 0x9a, 0xab, 0xe5, 0x61, 0x26, 0x3, 0x30 } }
> 
>    ## Include/Guid/MigratedFvInfo.h
> -  gEdkiiMigratedFvInfoGuid = { 0xc1ab12f7, 0x74aa, 0x408d, { 0xa2, 
> 0xf4, 0xc6, 0xce, 0xfd, 0x17, 0x98, 0x71 } }
> +  gEdkiiToMigrateFvInfoGuid = { 0xb4b140a5, 0x72f6, 0x4c21, { 0x93,
> 0xe4, 0xac, 0xc4, 0xec, 0xcb, 0x23, 0x23 } }
> +  gEdkiiMigratedFvInfoGuid  = { 0xc1ab12f7, 0x74aa, 0x408d, { 0xa2,
> 0xf4, 0xc6, 0xce, 0xfd, 0x17, 0x98, 0x71 } }
> 
>    ## Include/Guid/RngAlgorithm.h
>    gEdkiiRngAlgorithmUnSafe = { 0x869f728c, 0x409d, 0x4ab4, {0xac, 
> 0x03, 0x71, 0xd3, 0x09, 0xc1, 0xb3, 0xf4 }}
> --
> 2.29.2.windows.2



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