Change in coreboot[master]: src/drivers/intel/fsp2_0: allow larger FSP 2.0 header

[Nikolai Vyssotski (Code Review)]

Attention is currently required from: Furquan Shaikh, Martin Roth, Michał Żygowski, Marshall Dawson, Subrata Banik, Andrey Petrov, Patrick Rudolph, Nathaniel L Desimone.
Nikolai Vyssotski has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/56190 )

Change subject: src/drivers/intel/fsp2_0: allow larger FSP 2.0 header
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Patch Set 3:

(1 comment)

File src/drivers/intel/fsp2_0/include/fsp/info_header.h:

https://review.coreboot.org/c/coreboot/+/56190/comment/8e953b59_ff1ed33e 
PS2, Line 13:  however, some FSP 2.0 variants have it as well.
> > I don't think we should have the header length hardcoded, and should instead rely on that length f […]

I agree with Martin. This is not a matter of simply reporting a different FSP version via PcdFspHeaderSpecVersion (please note that it goes to 'SpecVersion' header field - naming is somewhat misleading here). If we change it to 2.2 we are implying that our FSP is 2.2 compliant which is not the case. We are FSP 2.0 compliant right now. If we were to report a different header version it would be via 'HeaderRevision' field (FSP_HEADER_REVISION_3 macro currently) but as I mentioned before we have no authority over issuing the FSP header versions so we may have a collision if we pick an arbitrary number to indicate different FSP 2.0 header length. I am ok with the solution you proposed above. It is better to check for a minimum length than not checking it at all.