[coreboot-gerrit] Change in coreboot[master]: cpu/x86/mp_init.c: Allocate the smm relocation stack on the heap

[Arthur Heymans (Code Review)]

Hello build bot (Jenkins), Jonathan Zhang, David Hendricks, Angel Pons, Aaron Durbin,

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

https://review.coreboot.org/c/coreboot/+/47072

to look at the new patch set (#4).

Change subject: cpu/x86/mp_init.c: Allocate the smm relocation stack on the heap
......................................................................

cpu/x86/mp_init.c: Allocate the smm relocation stack on the heap

The smm_module_loader v2 places stack_top at DEFAULT_SMBASE +
per_cpu_stack_size. The smm_stub assembly will put the stack for a CPU
at stack_top - apicid * stack_size. So for loader v2 this means that
areas below DEFAULT_SMBASE get used as a CPU stack. This would cause
lower memory corruption on S3 resume.

The solution is to use ramstage heap as a temporary place for the smm
relocation stacks. This completely avoids using lower memory for
CPU stacks.

On v1 all the CPU stacks would be properly allocated inside the
DEFAULT_SMBASE but this change won't hurt either.

Tested: works fine on OCP/Deltalake.

Change-Id: I125d3aa6526c923e154c41e2d586557c7d8f56c3
Signed-off-by: Arthur Heymans 
---
M src/cpu/x86/mp_init.c
M src/cpu/x86/smm/smm_module_loader.c
M src/cpu/x86/smm/smm_module_loaderv2.c
3 files changed, 33 insertions(+), 12 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/72/47072/4