[coreboot-gerrit] [S] Change in coreboot[main]: cpu/x86/smm: Fix get_save_state calculation

[Jérémy Compostella (Code Review)]

Attention is currently required from: EliasOfWaffle, Martin L Roth, Michał Żygowski, Paul Menzel, Stefan Reinauer.

Jérémy Compostella has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/78889?usp=email )

Change subject: cpu/x86/smm: Fix get_save_state calculation
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Patch Set 1:

(5 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/78889/comment/6dccfa3d_d41c89b3 :
PS1, Line 9: When the STM is configured, get_save_state returns an incorrect
nit: This is more of my rule as I don't think I saw that in coreboot coding style but I usually feel like this is good to define acronyms as they are used in the commit message. I would suggest: `When the SMI Transfer Monitor (STM) is configured` and line 11 `of the processor System Management Mode (SMM) descriptor`.

Patchset:

PS1: 
Just a few cosmetic and optional comments.

File src/cpu/x86/smm/smm_module_handler.c:

https://review.coreboot.org/c/coreboot/+/78889/comment/f404b014_15a69d52 :
PS1, Line 12: #include <security/intel/stm/SmmStm.h>
includes are usually sorted in alphabetical order.

https://review.coreboot.org/c/coreboot/+/78889/comment/90881efc_a0fee3ff :
PS1, Line 104: 	size_t stm_psd_size = 0;
I feel like the following is more readable but this is totally optional.
```
size_t size = smm_runtime.save_state_size;

if (cpu > smm_runtime.num_cpus)
    return NULL;

if (CONFIG(STM))
    size += ALIGN_UP(sizeof(TXT_PROCESSOR_SMM_DESCRIPTOR), 0x100);

return (void *)(smm_runtime.save_state_top[cpu] - size);
```

https://review.coreboot.org/c/coreboot/+/78889/comment/e96af259_d2e9f932 :
PS1, Line 111: 					0x100);
It should fit on one line. The coding style states 96 columns.