[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, Eugene Myers, 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 2:

(1 comment)

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

https://review.coreboot.org/c/coreboot/+/78889/comment/69409c9b_cc9d8eab :
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);
```