[M] Change in coreboot[master]: cpu/x86/smm: Add PCI BAR store functionality

[Robert Zieba (Code Review)]

Attention is currently required from: Arthur Heymans, Robert Zieba, Raul Rangel, Nico Huber, Angel Pons, Karthik Ramasubramanian, Felix Held.

Hello Arthur Heymans, build bot (Jenkins), Martin Roth, Karthik Ramasubramanian, Felix Held,

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

https://review.coreboot.org/c/coreboot/+/67931

to look at the new patch set (#6).

Change subject: cpu/x86/smm: Add PCI BAR store functionality
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cpu/x86/smm: Add PCI BAR store functionality

In certain cases data within protected memmory areas like SMRAM could
be leaked or modified if an attacker remaps PCI BARs to point within
that area. This commit adds support to the existing SMM to allow storing
PCI BARs in SMRAM and then later retrieved.

BUG=b:186792595

Signed-off-by: Robert Zieba 
Change-Id: I23fb1e935dd1b89f1cc5c834cc2025f0fe5fda37
---
M src/cpu/x86/Kconfig
M src/cpu/x86/smm/Makefile.inc
A src/cpu/x86/smm/pci_bar_store.c
M src/cpu/x86/smm/smm_module_handler.c
M src/cpu/x86/smm/smm_module_loader.c
M src/include/cpu/x86/smm.h
6 files changed, 143 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/31/67931/6