Star:
  The patch is good.  Reviewed-by: Liming Gao <liming....@intel.com>

Thanks
Liming
From: Zeng, Star [mailto:star.z...@intel.com]
Sent: Monday, June 24, 2013 7:29 PM
To: edk2-devel@lists.sourceforge.net
Subject: [edk2] [PATCH 1/2] MdeModulePkg and SecurityPkg: PEI variable does not 
robustly handle crashes during Reclaim().


==========

MdeModulePkg: Variable drivers robustly handle crashes during Reclaim().



PEI variable implementation checks only the variable header signature for 
validity. This does not seem robust if system crash occurred during previous 
Reclaim() operation. If the crash occurred while FTW was rewriting the variable 
FV, the signature could be valid even though the rest of the FV isn't valid.

Solution: Add a FaultTolerantWritePei driver to check and provide the FTW last 
write status, then PEI variable and early phase(before FTW protocol ready) of 
DXE variable can check the status and determine if all or partial variable data 
has been backed up in spare block, and then use the backed up data.



Contributed-under: TianoCore Contribution Agreement 1.0

Signed-off-by: Star Zeng <star.z...@intel.com<mailto:star.z...@intel.com>>

==========

SecurityPkg: Variable drivers robustly handle crashes during Reclaim().



PEI variable implementation checks only the variable header signature for 
validity. This does not seem robust if system crash occurred during previous 
Reclaim() operation. If the crash occurred while FTW was rewriting the variable 
FV, the signature could be valid even though the rest of the FV isn't valid.

Solution: PEI variable and early phase(before FTW protocol ready) of DXE 
variable can check the FTW last write status provided by FaultTolerantWritePei 
and determine if all or partial variable data has been backed up in spare 
block, and then use the backed up data.



Contributed-under: TianoCore Contribution Agreement 1.0

Signed-off-by: Star Zeng <star.z...@intel.com<mailto:star.z...@intel.com>>

==========



[Impact]

1. If Platforms use VariablePei.inf now, they need to add 
FaultTolerantWritePei.inf into the platform *.dsc and *.inf. Because PEI 
variable will be updated to depend on the added FaultTolerantWritePei.

2. The signature of working block header needs to be updated to 
gWorkingBlockSignatureGuid because FTW write header and record will be updated 
and exposed to support crossing archs. Low impact to platform because 
FaultTolerantWrite DXE driver can help correct or add the working block header 
at the first boot if platform *.fdf uses the old signature GUID or no working 
block header init data.





Thanks!

Star
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