FIT image: load secure FPGA

[Alex G.]

On 10/4/21 3:32 PM, Jorge Ramirez-Ortiz, Foundries wrote:
> Hello,
> 
> We are enabling secure boot on Zynqmp with SPL.
> 
> The issue however is that during secure boot, the bootrom not only
> validates the first loader (SPL and PMUFW combo) but it will also
> expect a signed bitstream during load(FPGA).
> 
> Since currently the SPL load of an FPGA image from FIT does not
> support loading images for authentication (fpga_loads), I'd like to
> discuss how to best implement such support.

What do you mean by "loading images for authentication" ?
> 
> A pretty standard file.its description of the FPGA loadable looks like
> this:
> 
>   fpga {
>        description = "FPGA binary";
>        data = /incbin/("${DEPLOY_DIR_IMAGE}/${SPL_FPGA_BINARY}");
>        type = "fpga";
>        arch = "${UBOOT_ARCH}";
>        compression = "none";
>        load = <${fpgaloadaddr}>;
>        hash-1 {
>        	     algo = "${FIT_HASH_ALG}";
> 	     };
>        };
> 
> We could extend imagetool.h struct image_tool_params to add more
> params or perhpas just define different 'types' of fpga?


Check "4) '/images' node"
   in doc/uImage.FIT/source_file_format.txt

The intent is to give either:
    * loadaddr="$(addr)" : copy image to $(addr), Done
    * compatible="": Use this driver to upload the FPGA

It seems to me like the right way to go is to make a new compatible="" 
FPGA loader is for fpga_load():

	fpga {
		description = "FPGA binary";
		data = /incbin/("${YOCTO_BS_PATH}");
		type = "fpga";
		compression = "none";
		compatible = "zynqmp-fancy-fpga",
		hash-1 {
			algo = "${FIT_HASHISH}";
		};
	};


> Something like:
>    "fpga"
>    "fpga-auth" : authenticated
>    "fpga-enc"  : encrypted
>    "fpga-sec"  : encrypted and authenticated

Can these properties be inferred from the FPGA image? If not, they could 
be required when using a new fpga loader. I don't think they should be 
added to "fpga-legacy".

Alex

> Then it would be a matter of modifying
> https://github.com/u-boot/u-boot/blob/master/common/spl/spl_fit.c#L572
> 
> any thoughts?
> 
> TIA
> Jorge
>