Re: [edk2-devel] [PATCH v4 0/5] Simplify SMM Relocation Process

["Ni, Ray" <ray.ni@intel.com>]

Jiaxin,
I provide separate review comments for each patch.

Can you please make sure the copy right year is updated for every file change?
I may not emphasize this for each patch.

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Wu, Jiaxin
> Sent: Friday, February 10, 2023 2:05 PM
> To: devel@edk2.groups.io
> Subject: [edk2-devel] [PATCH v4 0/5] Simplify SMM Relocation Process
> 
> Existing SMBASE Relocation is in the PiSmmCpuDxeSmm driver, which
> will relocate the SMBASE of each processor by setting the SMBASE
> field in the saved state map (at offset 7EF8h) to a new value.
> The RSM instruction reloads the internal SMBASE register with the
> value in SMBASE field when each time it exits SMM. All subsequent
> SMI requests will use the new SMBASE to find the starting address
> for the SMI handler (at SMBASE + 8000h).
> 
> Due to the default SMBASE for all x86 processors is 0x30000, the
> APs' 1st SMI for rebase has to be executed one by one to avoid
> the CPUs over-writing each other's SMM Save State Area (see
> existing SmmRelocateBases() function), which means the next AP has
> to wait for the previous AP to finish its 1st SMI, then it can call
> into its 1st SMI for rebase via Smi Ipi command, thus leading the
> existing SMBASE Relocation has to be running in series. Besides, it
> needs very complex code to handle the AP exit semaphore
> (mRebased[Index]), which will hook return address of SMM Save State
> so that semaphore code can be executed immediately after AP exits
> SMM for SMBASE relocation (see existing SemaphoreHook() function).
> 
> This series is to add the new SMM Base HOB for any PEI module to do
> the SmBase relocation ahead of PiSmmCpuDxeSmm driver and store the
> relocated SmBase address in array for each Processors. When the
> SMBASE relocation happens in a PEI module, the PEI module shall
> produce the SMM_BASE_HOB in HOB database which tells the
> PiSmmCpuDxeSmm driver (runs at a later phase) about the new SMBASE
> for each CPU thread. PiSmmCpuDxeSmm driver installs the SMI handler
> at the SMM_BASE_HOB.SmBase[Index]+0x8000 for CPU thread Index. When
> the HOB doesn't exist, PiSmmCpuDxeSmm driver shall relocate and
> program the new SMBASE itself (keep existing SMBASE Relocation way).
> 
> With SMM Base Hob support, PiSmmCpuDxeSmm does not need the RSM
> instruction to do the SMBASE Relocation. SMBASE Register for each
> processors have already been programmed and all SMBASE address have
> recorded in SMM Base Hob. So the same default SMBASE Address
> (0x30000) will not be used, thus the CPUs over-writing each other's
> SMM Save State Area will not happen in PiSmmCpuDxeSmm driver. This
> way makes the first SMI init can be executed in parallel and save
> boot time on multi-core system. Besides, Semaphore Hook code logic
> is also not required, which will greatly simplify the SMBASE
> Relocation flow.
> 
> Note:
> This is the new way that firmware can program the SMBASE
> independently of the RSM instruction. The PEI code performing
> this logic will not be open sourced, similarly to other things
> that are kept binary-only in the FSP. Due to the register
> difference in different vender, and it has not been documented
> in the Intel SDM yet, we need a new binary-only interface for
> SMM Base HOB.
> 
> Jiaxin Wu (5):
>   UefiCpuPkg/PiSmmCpuDxeSmm: Fix invalid InitializeMpSyncData call
>   UefiCpuPkg/SmmBaseHob.h: Add SMM Base HOB Data
>   UefiCpuPkg/PiSmmCpuDxeSmm: Consume SMM Base Hob for SmBase info
>   UefiCpuPkg/SmmCpuFeaturesLib: Skip SMBASE configuration
>   OvmfPkg/SmmCpuFeaturesLib: Check SmBase relocation supported or not
> 
>  .../Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c  |   8 +
>  .../SmmCpuFeaturesLib/SmmCpuFeaturesLib.inf        |   4 +
>  UefiCpuPkg/Include/Guid/SmmBaseHob.h               |  64 +++++++
>  .../Library/SmmCpuFeaturesLib/CpuFeaturesLib.h     |   2 +
>  .../SmmCpuFeaturesLib/IntelSmmCpuFeaturesLib.c     |  23 ++-
>  .../SmmCpuFeaturesLib/SmmCpuFeaturesLib.inf        |   4 +
>  .../SmmCpuFeaturesLib/SmmCpuFeaturesLibStm.inf     |   1 +
>  UefiCpuPkg/Library/SmmCpuFeaturesLib/SmmStm.c      |   1 -
>  .../StandaloneMmCpuFeaturesLib.inf                 |   4 +
>  UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c                  |  29 +++-
>  UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c              |  23 +++
>  UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c         | 191
> ++++++++++++++++-----
>  UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h         |  24 +++
>  UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf       |   1 +
>  UefiCpuPkg/UefiCpuPkg.dec                          |   3 +
>  15 files changed, 332 insertions(+), 50 deletions(-)
>  create mode 100644 UefiCpuPkg/Include/Guid/SmmBaseHob.h
> 
> --
> 2.16.2.windows.1
> 
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