[S] Change in coreboot[main]: drivers/intel/fsp2_0: Support FSP-M execution from CBFS cache

[Jérémy Compostella (Code Review)]

Attention is currently required from: Andrey Petrov, Arthur Heymans, Bora Guvendik, Chen, Gang C, Dinesh Gehlot, Eran Mitrani, Jakub Czapiga, Kapil Porwal, Paul Menzel, Ronak Kanabar, Shuo Liu, Subrata Banik, Tarun.

Hello Andrey Petrov, Arthur Heymans, Bora Guvendik, Chen, Gang C, Dinesh Gehlot, Eran Mitrani, Jakub Czapiga, Kapil Porwal, Paul Menzel, Ronak Kanabar, Shuo Liu, Subrata Banik, Tarun, build bot (Jenkins),

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/81212?usp=email

to look at the new patch set (#10).

The following approvals got outdated and were removed:
Verified-1 by build bot (Jenkins)

Change subject: drivers/intel/fsp2_0: Support FSP-M execution from CBFS cache
......................................................................

drivers/intel/fsp2_0: Support FSP-M execution from CBFS cache

If SPINOR space is limited and Cache-As-RAM (CAR) is large enough, FSP
can be stored compressed, loaded in CBFS cache and executed from
there. It allows to reduce the FSP-M SPINOR footprint with a limited
boot time penalty. `FSP_M_EXECUTE_FROM_CBFS_CACHE' Kconfig can be set
to turn on this feature.

We performed some measurements on a Meteor Lake Rex board with a 2 MB
Cache-As-RAM (`DCACHE_RAM_SIZE' at 0x200000 and `DCACHE_RAM_BASE'
0xea000000) and a few adjustments in the FSP to enable CAR to RAM
PEIM (Pre-EFI Initialization Module) drivers migration.

1. Time impact

| Compression algorithm    | LZ4      | LZMA     |
|--------------------------+----------+----------|
| Decompress duration      |   1.9 ms |  75.6 ms |
| Overall boot time impact | +15.9 ms | +77.4 ms |

The overall boot time impact increase is explained by FSP-M loading
being a bit faster (-18 ms) undermined by a longer Cache-As-RAM
setup (32 ms).

2. SPINOR impact

| CBFS file / Compression    | LZ4            | LZMA            |
|----------------------------+----------------+-----------------|
| romstage size              |   +4 KB  (+3%) |   +10 KB (+8%)  |
| fspm.bin size              | -313 KB (-37%) |  -456 KB (-54%) |
|----------------------------+----------------+-----------------|
| Total Per slot             | -309 KB        |  -446 KB        |
| Total for SPINOR (3 slots) | -926 KB        | -1339 KB        |

BUG=b:329237541
TEST=Verified on rex with Cache-AS-RAM size of 2 MB

Change-Id: I8d42d765eb0ecf2e7a8fc6d8d15eb2df8975f6f2
Signed-off-by: Jeremy Compostella 
---
M src/drivers/intel/fsp2_0/Kconfig
M src/drivers/intel/fsp2_0/Makefile.mk
M src/drivers/intel/fsp2_0/memory_init.c
M src/soc/intel/meteorlake/Kconfig
4 files changed, 40 insertions(+), 2 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/12/81212/10