Hi Udit, 
> Hi  Ilias
> 
> > -----Original Message-----
> > From: Ilias Apalodimas <[email protected]>
> > Sent: Friday, May 24, 2019 9:57 PM
> > To: Udit Kumar <[email protected]>
> > Cc: [email protected]; Varun Sethi <[email protected]>
> > Subject: Re: [EXT] Securing the boot flow in U-Boot
> > 
> > Caution: EXT Email
> > 
> > Hi Udit,
> > > >
> > > > What do you think?
> > >
> > > Here we are talking about image signing and image validation.
> > > I am not sure, what are your plan to make keys data base (platform
> > > key, KeK and DBs) secure while writing.
> > > AFAIU, This is one of requirement of secure uefi that these secure 
> > > variable
> > should be written in MM mode.
> > The plan on that is run stMM as an OP-TEE TA.
> > This will allow us to run StMM + fTPM simultaneously.
> > The current plan is to support UEFI specs on U-Boot without having secure
> > variable storage. That one is our next step.
> 
> May be I am asking too early about your next step 
Indeed :)
We'll try to have the UEFI secure boot spec in u-boot first, *without* storing
the variables in a secure storage. Once we complete this we can start planning
the secure part of the varibles.

A bit of history on this. One of the things we are going to try is split
U-Boot ENV and UEFI variables. By decoupling those, storing the variables in a
different storage should be straightforward (or at least  a lot easier than it
is today).
> Where you see flash driver sitting, 
> Possible options I see, 
> 1/ In OP-TEE and  StMM is making sys-call to access it 
> 2/ in TFA (EL3) itself and stMM is making smc calls 
> 3/ OP-TEE is doing sort of mmap to flash controller area and driver is 
> residing in Sec-EL0 itself 
All three sound valid. This also depends on the hardware design as well. This is
too soon for us, if anyone else has any suggestions it might be a good idea to
sum those up in a new thread?

Thanks
/Ilias
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