RE: [RFC PATCH 2/4] fpga: Add new properties to support user-key encrypted bitstream loading

[Nava kishore Manne]

Hi Rob,

	Please find my response inline.

> -----Original Message-----
> From: Rob Herring <robh@xxxxxxxxxx>
> Sent: Thursday, May 13, 2021 8:01 AM
> To: Nava kishore Manne <navam@xxxxxxxxxx>
> Cc: mdf@xxxxxxxxxx; trix@xxxxxxxxxx; Michal Simek <michals@xxxxxxxxxx>;
> arnd@xxxxxxxx; Rajan Vaja <RAJANV@xxxxxxxxxx>;
> gregkh@xxxxxxxxxxxxxxxxxxx; linus.walleij@xxxxxxxxxx; Amit Sunil Dhamne
> <amitsuni@xxxxxxxxxxxxxxx>; Tejas Patel <tejasp@xxxxxxxxxxxxxxx>;
> zou_wei@xxxxxxxxxx; Manish Narani <MNARANI@xxxxxxxxxx>; Sai Krishna
> Potthuri <lakshmis@xxxxxxxxxx>; Jiaying Liang <jliang@xxxxxxxxxx>; linux-
> fpga@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; git
> <git@xxxxxxxxxx>; chinnikishore369@xxxxxxxxx
> Subject: Re: [RFC PATCH 2/4] fpga: Add new properties to support user-key
> encrypted bitstream loading
> 
> On Tue, May 04, 2021 at 03:52:25PM +0530, Nava kishore Manne wrote:
> > This patch Adds ‘encrypted-key-name’ and
> > ‘encrypted-user-key-fpga-config’ properties to support user-key
> > encrypted bitstream loading use case.
> >
> > Signed-off-by: Nava kishore Manne <nava.manne@xxxxxxxxxx>
> > ---
> >  Documentation/devicetree/bindings/fpga/fpga-region.txt | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/fpga/fpga-region.txt
> > b/Documentation/devicetree/bindings/fpga/fpga-region.txt
> > index d787d57491a1..957dc6cbcd9e 100644
> > --- a/Documentation/devicetree/bindings/fpga/fpga-region.txt
> > +++ b/Documentation/devicetree/bindings/fpga/fpga-region.txt
> > @@ -177,6 +177,9 @@ Optional properties:
> >  	it indicates that the FPGA has already been programmed with this
> image.
> >  	If this property is in an overlay targeting a FPGA region, it is a
> >  	request to program the FPGA with that image.
> > +- encrypted-key-name : should contain the name of an encrypted key file
> located
> > +	on the firmware search path. It will be used to decrypt the FPGA
> image
> > +	file.
> >  - fpga-bridges : should contain a list of phandles to FPGA Bridges that must
> be
> >  	controlled during FPGA programming along with the parent FPGA
> bridge.
> >  	This property is optional if the FPGA Manager handles the bridges.
> > @@ -187,6 +190,8 @@ Optional properties:
> >  - external-fpga-config : boolean, set if the FPGA has already been
> configured
> >  	prior to OS boot up.
> >  - encrypted-fpga-config : boolean, set if the bitstream is encrypted
> > +- encrypted-user-key-fpga-config : boolean, set if the bitstream is
> encrypted
> > +	with user key.
> 
> What's the relationship with encrypted-fpga-config? Both present or
> mutually exclusive? Couldn't this be implied by encrypted-key-name being
> present?
> 

In Encryption we have two kinds of use case one is Encrypted Bitstream loading with Device-key and
Other one is Encrypted Bitstream loading with User-key. encrypted-fpga-config and encrypted-user-key-fpga-config 
are mutually exclusive. To differentiate both the use cases I have added this new flag and Aes Key file(encrypted-key-name)
is needed only for encrypted-user-key-fpga-config use cases.

Regards,
Navakishore.