[L] Change in coreboot[main]: cpu/x86/smm/smm_module_handler: Protect SMM using Nx bit

[Patrick Rudolph (Code Review)]

Attention is currently required from: Jérémy Compostella, Shuo Liu.

Patrick Rudolph has posted comments on this change by Patrick Rudolph. ( https://review.coreboot.org/c/coreboot/+/87357?usp=email )

Change subject: cpu/x86/smm/smm_module_handler: Protect SMM using Nx bit
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Patch Set 3:

(1 comment)

Commit Message:

https://review.coreboot.org/c/coreboot/+/87357/comment/eb12197e_84cf9c4e?usp... :
PS3, Line 31: TEST: Booted on qemu x86_64 enabled.
> Were you able, through hack and dedicated tests, to verify that the policies are set up properly? Fo […]

I confirmed that NX bit is working. Stack and heap are no longer executable.
My tests also showed that RO memory is still writable. Will investigate why (if that's an QEMU issue or a bug in the code).