OvmfPkg/PlatformInitLib: Create gEfiSmmSmramMemoryGuid
In the PiSmmCpuDxeSmm driver, SMRAM allocation for SMI
handlers and processor Save State areas was traditionally
performed using the Smst->AllocatePages() function during
the DXE phase. The introduction of SmmRelocationLib
changes this process by moving the allocation to the PEI
phase, where Smst->AllocatePages() is not accessible.
Instead, the allocation is now handled by partitioning
the SMRAM based on the information provided by a GUID HOB
(identified by gEfiSmmSMramMemoryGuid).
This patch is to ensure that OVMF produces the
gEfiSmmSMramMemoryGuid HOB, allowing SmmRelocationLib to
reserve the necessary memory for SMBASE relocation.
More info for the change:
1. The EFI_SMM_SMRAM_MEMORY_GUID HOB, as defined in the PI
specification, vol.3, section 5, which is used to describe
the SMRAM memory regions supported by the platform. This HOB
should be produced during the memory detection phase to
align with the PI spec.
2. In addition to the memory reserved for ACPI S3 resume,
an increasing number of features require reserving SMRAM
for specific purposes, such as SmmRelocation. Other
advanced features in Intel platforms also necessitate
this. The implementation of these features varies and is
entirely dependent on the platform. This is why an
increasing number of platforms are adopting the
EFI_SMM_SMRAM_MEMORY_GUID HOB for SMRAM description.
3. It is crucial that the SMRAM information remains
consistent when retrieved from the platform, whether
through the SMM ACCESS PPI/Protocol or the
EFI_SMM_SMRAM_MEMORY_GUID HOB. Inconsistencies can lead
to unexpected issues, most commonly memory region conflicts.
4. The SMM ACCESS PPI/Protocol can be naturally
implemented for general use. The common approach is to
utilize the EFI_SMM_SMRAM_MEMORY_GUID HOB. For reference,
see the existing implementation in the EDK2 repository at
edk2/UefiPayloadPkg/SmmAccessDxe/SmmAccessDxe.inf and
edk2-platforms/Silicon/Intel/IntelSiliconPkg/Feature/
SmmAccess/Library/PeiSmmAccessLib/PeiSmmAccessLib.inf.
Next patch will refine the OVMF SMM Access to consume
the EFI_SMM_SMRAM_MEMORY_GUID HOB.
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Ray Ni <ray.ni@intel.com>
Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>
Tested-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Jiewen Yao <Jiewen.yao@intel.com>
2 files changed
