[CHERRY-PICK] StandaloneMmPkg: Split MmEvent to a separate Driver

[K-Pavana]

Description

Needed to integrate Intel ref code without the change due to a build issue.

---

Due to PEIM will do following MM notify event under API mode:

1. MM end of dxe notify Event
2. MM ready to lock notify Event
3. MM ready to boot notify Event
4. MM exit boot services notify Event

It will conflict with the notify event in MmCommunicationDxe.inf on edk2 bootloader under API mode, so split following MmEvent to MmCommunicationNotifyDxe.inf, and avoid run this driver under API mode.

Cc: Ray Ni ray.ni@intel.com
Cc: Star Zeng star.zeng@intel.com
Cc: Jiaxin Wu jiaxin.wu@intel.com
Cc: Dun Tan dun.tan@intel.com
Cc: Khor Swee Aun swee.aun.khor@intel.com
Cc: Sami Mujawar sami.mujawar@arm.com
Cc: Ard Biesheuvel ardb+tianocore@kernel.org
(cherry picked from commit e44cb97)

• Impacts functionality?
• Impacts security?
• Breaking change?
• Includes tests?
• Includes documentation?

How This Was Tested

Code that uses this change on a server platform

Integration Instructions

Todo

[makubacki]

@K-Pavana. I've updated the integration instructions in the PR description for "N/A" to "Todo". There are definitely integration instructions and this is a breaking change.

Please update the integration instructions to explain:

1. What platforms are impacted by this change (e.g. those that use MmCommunicationDxe in StandaloneMmPkg)
2. What is expected of those platforms (e.g. add the new module and keep the original)
3. What is expected by platforms that use Mu MM Supervisor communication

[kuqin12]

@makubacki do you understand the commit message? Where in PEIM are they doing these events?

[makubacki]

@makubacki do you understand the commit message? Where in PEIM are they doing these events?

Given it is talking about "API mode", I assume what it means is that:

"FSP has API mode and dispatch mode. Because dispatch mode is PI-compatible, it can register real DXE handlers. Because API mode is intended to work with non-PI bootloaders, all of its event handlers must be registered in PEI (a PEIM) because FSP hosts its own PEI core in API mode. However, nothing stops API mode from being used by a PI-compatible (edk2) wrapper that has DXE. In that case, we now have a DXE driver, MmCommunicationDxe that duplicates functionality with the FSP API mode PEIM. Let's avoid that by splitting the conflicting code to a separate driver that is not included in API mode."

[kuqin12]

I know this is a cherry-pick, but where is the close call?