Tianocore/edk2.git/OvmfPkg/Library/SmmRelocationLib/InternalSmmRelocationLib.h, branch master

OvmfPkg: SmmRelocationLib: Optimize SMI init 16-bit bootstrapping

2026-09-29T09:12:40+00:00

Every once in a while the SMM relocation routine would hang the system. This is due to the 16-bit code after relocation could land at the end of a 4K page boundary. Then the code fetching into the next page will trip on QEMU block-exit handling logic, which will truncate the EIP with 0xFFFF, causing the code to read back garbage and fault. This change short-circuits the jump by copying the entire 16-bit stub over to the BASE + 0x8000 location. The GDTr is also moved to the same location, otherwise we could risk reaching out to a different page because it is marked in a different section inside this image. Signed-off-by: Kun Qin

OvmfPkg: Replace include guards with #pragma once

2026-02-23T21:01:28+00:00

Replace traditional `#ifndef`/`#define`/`#endif` include guards with `#pragma` once. `#pragma once` is a widely supported preprocessor directive that prevents header files from being included multiple times. It is supported by all toolchains used to build edk2: GCC, Clang/LLVM, and MSVC. Note: Headers taken directly from external projects, such as those in OvmfPkg/Include/IndustryStandard/Xen/ were not modified since they may be periodically re-synced and do not follow other edk2 coding stadards. Compared to macro-based include guards, `#pragma once`: - Eliminates the risk of macro name collisions or copy/paste errors where two headers inadvertently use the same guard macro. - Eliminate inconsistency in the way include guard macros are named (e.g., some files use `__FILE_H__`, others use `FILE_H_`, etc.). - Reduces boilerplate (three lines replaced by one). - Avoids polluting the macro namespace with guard symbols. - Can improve build times as the preprocessor can skip re-opening the file entirely, rather than re-reading it to find the matching `#endif` ("multiple-include optimization"). - Note that some compilers may already optimize traditional include guards, by recognzining the idiomatic pattern. This change is made acknowledging that overall portability of the code will technically be reduced, as `#pragma once` is not part of the C/C++ standards. However, this is considered acceptable given: 1. edk2 already defines a subset of supported compilers in BaseTools/Conf/tools_def.template, all of which have supported `#pragma once` for over two decades. 2. There have been concerns raised to the project about inconsistent include guard naming and potential macro collisions. Approximate compiler support dates: - MSVC: Supported since Visual C++ 4.2 (1996) - GCC: Supported since 3.4 (2004) (http://gnu.ist.utl.pt/software/gcc/gcc-3.4/changes.html) - Clang (LLVM based): Since initial release in 2007 Signed-off-by: Michael Kubacki

OvmfPkg/SmmRelocationLib: Add library instance for OVMF

2024-05-08T01:53:58+00:00

There are below 2 differences between AMD & OVMF according existing implementation: 1.The mode of the CPU check is different between the AMD & OVMF. OVMF: CpuSaveState->x86.SMMRevId & 0Xffff AMD: LMAValue = (UINT32)AsmReadMsr64 (EFER_ADDRESS) & LMA 2.Existing SmBase configuration is different between the AMD & OVMF. OVMF: if ((CpuSaveState->x86.SMMRevId & 0xFFFF) == 0) { CpuSaveState->x86.SMBASE = mSmBaseForAllCpus[CpuIndex]; } else { CpuSaveState->x64.SMBASE = mSmBaseForAllCpus[CpuIndex]; } AMD: AmdCpuState->x64.SMBASE = mSmBaseForAllCpus[CpuIndex]; This patch provides the SmmRelocationLib library instance for OVMF to handle the logic difference, and it won't change the existing implementation code logic. Cc: Ray Ni Cc: Zeng Star Cc: Ard Biesheuvel Cc: Jiewen Yao Cc: Gerd Hoffmann Cc: Rahul Kumar Signed-off-by: Jiaxin Wu Tested-by: Gerd Hoffmann Acked-by: Gerd Hoffmann Acked-by: Jiewen Yao