[XS] Change in coreboot[master]: smm: Invalid the smm handler region instead of the whole

[Arthur Heymans (Code Review)]

Attention is currently required from: Bao Zheng, Fred Reitberger, Jason Glenesk, Matt DeVillier, Raul Rangel, Zheng Bao.

Arthur Heymans has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/69783?usp=email )

Change subject: smm: Invalid the smm handler region instead of the whole
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Patch Set 4: Code-Review-2

(1 comment)

Patchset:

PS4: 
The whole point of using TSEG as a stage cache is that the OS can't touch it. What data are your trying to access or place that resides in TSEG after SMM relocation?

Also the MSR needs to be aligned and a multiple of 128K for which there is no guarantee the subregion is.