Re: [PATCH 01/12] MdeModulePkg Variable: Add some missing changes for 9b18845

[Laszlo Ersek <lersek@redhat.com>]

Hi Star,

On 01/13/19 16:37, Star Zeng wrote:
> 9b18845a4b4cd1d2cf004cbc1cadf8a93ccb37ea changed the code
> which read from physical MMIO address to read from memory cache.
> 
> The patch adds some missing changes for it.
> 
> I found them when updating code for
> https://bugzilla.tianocore.org/show_bug.cgi?id=1323
> Merge EmuVariable and Real variable driver.
> 
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Hao Wu <hao.a.wu@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Star Zeng <star.zeng@intel.com>
> ---
>  MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c    | 12 +++++-------
>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableDxe.c |  6 +++---
>  2 files changed, 8 insertions(+), 10 deletions(-)

Please update the commit message to clarify the change.

Commit 9b18845a4b4c ("MdeModulePkg Variable: Enhance variable
performance by reading from existed memory cache.", 2015-10-23) was a
performance optimization. Therefore, there can be two issues with it:

(a) it may have missed another opportunity for performance improvement,

(b) it may have introduced a regression.

Can you please clarify the issue? The explanation should be part of the
commit message.

Dependent on (a) vs. (b), the impact of this change could differ greatly.

Thanks!
Laszlo


> 
> diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c b/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
> index 443cf07144a1..99d487adac9e 100644
> --- a/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
> +++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
> @@ -16,7 +16,7 @@
>    VariableServiceSetVariable() should also check authenticate data to avoid buffer overflow,
>    integer overflow. It should also check attribute to avoid authentication bypass.
>  
> -Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
> +Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
>  (C) Copyright 2015-2018 Hewlett Packard Enterprise Development LP<BR>
>  This program and the accompanying materials
>  are licensed and made available under the terms and conditions of the BSD License
> @@ -262,13 +262,12 @@ UpdateVariableStore (
>    UINT8                       *CurrBuffer;
>    EFI_LBA                     LbaNumber;
>    UINTN                       Size;
> -  EFI_FIRMWARE_VOLUME_HEADER  *FwVolHeader;
>    VARIABLE_STORE_HEADER       *VolatileBase;
>    EFI_PHYSICAL_ADDRESS        FvVolHdr;
>    EFI_PHYSICAL_ADDRESS        DataPtr;
>    EFI_STATUS                  Status;
>  
> -  FwVolHeader = NULL;
> +  FvVolHdr    = 0;
>    DataPtr     = DataPtrIndex;
>  
>    //
> @@ -281,7 +280,6 @@ UpdateVariableStore (
>      Status = Fvb->GetPhysicalAddress(Fvb, &FvVolHdr);
>      ASSERT_EFI_ERROR (Status);
>  
> -    FwVolHeader = (EFI_FIRMWARE_VOLUME_HEADER *) ((UINTN) FvVolHdr);
>      //
>      // Data Pointer should point to the actual Address where data is to be
>      // written.
> @@ -290,7 +288,7 @@ UpdateVariableStore (
>        DataPtr += mVariableModuleGlobal->VariableGlobal.NonVolatileVariableBase;
>      }
>  
> -    if ((DataPtr + DataSize) > ((EFI_PHYSICAL_ADDRESS) (UINTN) ((UINT8 *) FwVolHeader + FwVolHeader->FvLength))) {
> +    if ((DataPtr + DataSize) > (FvVolHdr + mNvFvHeaderCache->FvLength)) {
>        return EFI_OUT_OF_RESOURCES;
>      }
>    } else {
> @@ -317,7 +315,7 @@ UpdateVariableStore (
>    //
>    // If we are here we are dealing with Non-Volatile Variables.
>    //
> -  LinearOffset  = (UINTN) FwVolHeader;
> +  LinearOffset  = (UINTN) FvVolHdr;
>    CurrWritePtr  = (UINTN) DataPtr;
>    CurrWriteSize = DataSize;
>    CurrBuffer    = Buffer;
> @@ -2739,7 +2737,7 @@ UpdateVariable (
>        }
>      }
>  
> -    State = Variable->CurrPtr->State;
> +    State = CacheVariable->CurrPtr->State;
>      State &= VAR_DELETED;
>  
>      Status = UpdateVariableStore (
> diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableDxe.c b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableDxe.c
> index 23186176be75..f7185df3a7eb 100644
> --- a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableDxe.c
> +++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableDxe.c
> @@ -3,7 +3,7 @@
>    and volatile storage space and install variable architecture protocol.
>  
>  Copyright (C) 2013, Red Hat, Inc.
> -Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
> +Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
>  (C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
>  This program and the accompanying materials
>  are licensed and made available under the terms and conditions of the BSD License
> @@ -402,8 +402,8 @@ FtwNotificationEvent (
>    //
>    // Mark the variable storage region of the FLASH as RUNTIME.
>    //
> -  VariableStoreBase   = NvStorageVariableBase + (((EFI_FIRMWARE_VOLUME_HEADER *)(UINTN)(NvStorageVariableBase))->HeaderLength);
> -  VariableStoreLength = ((VARIABLE_STORE_HEADER *)(UINTN)VariableStoreBase)->Size;
> +  VariableStoreBase   = NvStorageVariableBase + mNvFvHeaderCache->HeaderLength;
> +  VariableStoreLength = mNvVariableCache->Size;
>    BaseAddress = VariableStoreBase & (~EFI_PAGE_MASK);
>    Length      = VariableStoreLength + (VariableStoreBase - BaseAddress);
>    Length      = (Length + EFI_PAGE_SIZE - 1) & (~EFI_PAGE_MASK);
>