The RestoreLockBox() and RestoreAllLockBoxInPlace() functions handle the
case when EFI_PEI_SMM_COMMUNICATION_PPI.Communicate() returns
EFI_NOT_STARTED: they access the SMRAM directly, for restoring LockBox
data.
This occurs if a PEIM needs to restore LockBox data *before* the SMBASE is
relocated and the SMI handler is installed for all processors.
One such PEIM is UefiCpuPkg/Universal/Acpi/S3Resume2Pei. On the S3 resume
path, in function S3RestoreConfig2(), LockBox data are restored *before*
the SmmRestoreCpu() function of UefiCpuPkg/PiSmmCpuDxeSmm is called via
SmmS3ResumeState->SmmS3ResumeEntryPoint. (The latter SmmRestoreCpu()
function is responsible for the SMBASE relocation.)
If a platform knows that its PEIMs restore LockBox data *only* before
SMBASE relocation -- e.g., due to S3Resume2Pei being the platform's only
SmmLockBoxPeiLib client --, then the platform might not want to include
"UefiCpuPkg/PiSmmCommunication/PiSmmCommunicationPei.inf" at all (hence
not provide EFI_PEI_SMM_COMMUNICATION_PPI) -- because all of those
restores would be serviced by direct SMRAM access anyway.
Currently the absence of EFI_PEI_SMM_COMMUNICATION_PPI is not supported by
SmmLockBoxPeiLib, but it's not hard to implement. Handle it the same as
when EFI_PEI_SMM_COMMUNICATION_PPI.Communicate() returns EFI_NOT_STARTED:
restore LockBox data directly from SMRAM.
Suggested-by: Jiewen Yao <jiewen....@intel.com>
Cc: Jiewen Yao <jiewen....@intel.com>
Cc: Michael Kinney <michael.d.kin...@intel.com>
Cc: Jordan Justen <jordan.l.jus...@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <ler...@redhat.com>
---
Notes:
This allows me to drop the null implementation of
EFI_PEI_SMM_COMMUNICATION_PPI from the patch "OvmfPkg: add PEIM for
providing TSEG-as-SMRAM during PEI".
MdeModulePkg/Library/SmmLockBoxLib/SmmLockBoxPeiLib.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/MdeModulePkg/Library/SmmLockBoxLib/SmmLockBoxPeiLib.c
b/MdeModulePkg/Library/SmmLockBoxLib/SmmLockBoxPeiLib.c
index bd3204b..cea1fed 100644
--- a/MdeModulePkg/Library/SmmLockBoxLib/SmmLockBoxPeiLib.c
+++ b/MdeModulePkg/Library/SmmLockBoxLib/SmmLockBoxPeiLib.c
@@ -563,7 +563,10 @@ RestoreLockBox (
(VOID **)&SmmCommunicationPpi
);
if (EFI_ERROR (Status)) {
- return EFI_NOT_STARTED;
+ DEBUG ((EFI_D_INFO, "SmmLockBoxPeiLib LocatePpi - (%r)\n", Status));
+ Status = InternalRestoreLockBoxFromSmram (Guid, Buffer, Length);
+ DEBUG ((EFI_D_INFO, "SmmLockBoxPeiLib RestoreLockBox - Exit (%r)\n",
Status));
+ return Status;
}
//
@@ -682,7 +685,10 @@ RestoreAllLockBoxInPlace (
(VOID **)&SmmCommunicationPpi
);
if (EFI_ERROR (Status)) {
- return EFI_NOT_STARTED;
+ DEBUG ((EFI_D_INFO, "SmmLockBoxPeiLib LocatePpi - (%r)\n", Status));
+ Status = InternalRestoreAllLockBoxInPlaceFromSmram ();
+ DEBUG ((EFI_D_INFO, "SmmLockBoxPeiLib RestoreAllLockBoxInPlace - Exit
(%r)\n", Status));
+ return Status;
}
//
--
1.8.3.1
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