tree 678fc6970a1b9fe0b9f0749fae4ef8bd14cd44ef
parent f251a6a439e70d7003ee6a5fbfae79eab3971e75
author Subrata Banik <subratabanik@google.com> 1670573306 +0530
committer Felix Held <felix-coreboot@felixheld.de> 1671459251 +0000

soc/intel/meteorlake: Remove dependency of FSP-S CpuMpPei Module

This patch fixes a hidden issue present inside FSP-S while coreboot
decides to skip performing MP initialization by overriding FSP-S UPDs
as below:
 1. CpuMpPpi  ------> Passing `NULL` as coreboot assume FSP don't need
                      to use coreboot wrapper for performing any
                      operation over APs.

 2. SkipMpInit -----> Set `1` to let FSP know that coreboot decided
                      to skip FSP running CPU feature programming.

Unfortunately, the assumption of coreboot is not aligned with FSP when
it comes to the behaviour of `CpuMpPpi` UPD. FSP assumes ownership of
the APs (Application Processors) upon passing `NULL` pointer to the
`CpuMpPpi` FSP-S UPD.

FSP-S creates its own infrastructure code after seeing the CpuMpPpi
UPD is set to `NULL`. FSP requires the CpuMpPei module, file name
`UefiCpuPkg/CpuMpPei/CpuMpPei.c`, function name `InitializeCpuMpWorker`
to perform those additional initialization which is not relevant for
the coreboot upon selecting the SkipMpInit UPD to 1 (a.k.a avoid
running CPU feature programming on APs).

Additionally, FSP-S binary size has increased by ~30KB (irrespective of
being compressed) with the inclusion of the CpuMpPei module, which is
eventually not meaningful for coreboot.

Hence, this patch selects `MP_SERVICES_PPI_V2_NOOP` config
unconditionally to ensure pass a valid pointer to the `CpuMpPpi` UPD
and avoid APs getting hijacked by FSP while coreboot decides to set
SkipMpInit UPD.

Ideally, FSP should have avoided all AP related operations when
coreboot requested FSP to skip MP init by overriding required UPDs.

TEST=Able to drop CpuMpPei Module from FSP and boot to Chrome OS on
Google/Redrix, Kano, Taeko devices with SkipMpInit=1.

Without this patch:

Here is the CPU AP logs coming from the EDK2 (open-source)
[UefiCpuPkg/CpuMpPei/CpuMpPei.c] when coreboot sets `NULL` to the
CpuMpPpi UPD.

[SPEW ]  Loading PEIM EDADEB9D-DDBA-48BD-9D22-C1C169C8C5C6
[SPEW ]  Loading PEIM at 0x00076F9A000 EntryPoint=0x00076FA24E2
         CpuMpPei.efi PROGRESS CODE: V03020002 I0
[SPEW ]  Register PPI Notify: F894643D-C449-42D1-8EA8-85BDD8C65BDE
[SPEW ]  Notify: PPI Guid: F894643D-C449-42D1-8EA8-85BDD8C65BDE,
         Peim notify entry point: 76FA0239
AP Loop Mode is 2
GetMicrocodePatchInfoFromHob: Microcode patch cache HOB is not found.
CPU[0000]: Microcode revision = 00000000, expected = 00000000
[SPEW ]  Register PPI Notify: 8F9D4825-797D-48FC-8471-845025792EF6
Does not find any stored CPU BIST information from PPI!
  APICID - 0x00000000, BIST - 0x00000000
[SPEW ]  Install PPI: 9E9F374B-8F16-4230-9824-5846EE766A97
[SPEW ]  Install PPI: 5CB9CB3D-31A4-480C-9498-29D269BACFBA
[SPEW ]  Install PPI: EE16160A-E8BE-47A6-820A-C6900DB0250A
PROGRESS CODE: V03020003 I0

With this patch:

No instance of `CpuMpPei` has been found in the AP UART log with FSP
debug enabled.

This patch is backported from
commit 8409f156d588e74932924ae8aac69478a4b6388e (soc/intel/alderlake:
Remove dependency of FSP-S CpuMpPei Module)

Change-Id: I7d9fb37ca1cd4bf325edc951ee7293e459fa2ea4
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/70600
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Reviewed-by: Ivy Jian <ivy.jian@quanta.corp-partner.google.com>