[M] Change in coreboot[master]: soc/amd/common/block/apob: Add hashed APOB support

[Fred Reitberger (Code Review)]

Attention is currently required from: Jason Glenesk, Raul Rangel, Matt DeVillier, Martin Roth, Felix Held.

Fred Reitberger has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/67301 )

Change subject: soc/amd/common/block/apob: Add hashed APOB support
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Patch Set 5:

(2 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/67301/comment/78c65285_8b9f1e99 
PS4, Line 15: chausie
> I'm sure you could easily get one ;) […]

The ABL will tell us exactly how big the APOB is in the header field.  We reserve at least that much, probably rounded to the next biggest erasable block size (4k usually).  It's likely there is space at the end for this, but until I can test on actual hardware it's only a guess.

File src/soc/amd/common/block/apob/apob_cache.c:

https://review.coreboot.org/c/coreboot/+/67301/comment/56c8101a_fbe35792 
PS4, Line 57: apob_header_ptr->size + MRC_HASH_SIZE
> We know this via `CONFIG_PSP_APOB_DRAM_SIZE` don't we?

The actual size for Mendocino looks to be 0x1db18 which is why we reserved 0x1e000 (120k).  This leaves 1256 bytes free, of which the hash will use 8.