[PATCH V10 0/4] Add Intel TDX support in OvmfPkg/ResetVector

Min Xu

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3429

Intel's Trust Domain Extensions (Intel TDX) refers to an Intel technology
that extends Virtual Machines Extensions (VMX) and Multi-Key Total Memory
Encryption (MKTME) with a new kind of virutal machines guest called a
Trust Domain (TD). A TD is desinged to run in a CPU mode that protects the
confidentiality of TD memory contents and the TD's CPU state from other
software, including the hosting Virtual-Machine Monitor (VMM), unless
explicitly shared by the TD itself.

The patch-sets to support Intel TDX in OvmfPkg is split into several
waves. This is wave-1 which adds Intel TDX support in OvmfPkg/ResetVector.
Note: TDX only works in X64.

Patch #1: Ovmf uses its own Main.asm to reduce the complexity of Main.asm
in UefiCpuPkg. This Main.asm is an unmodified copy from
UefiCpuPkg/ReseteVector/Vtf0 (so no functional change) and the actual
changes for tdx come as incremental patches.

Patch #2: WORK_AREA_GUEST_TYPE is cleared in Main.asm instead of in

Patch #3: Introduce IntelTdxMetadata.asm which describes the information
about the image for VMM use.

Patch #4: Enable TDX in OvmfPkg/ResetVector for ARCH_X64.

[TDX]: https://software.intel.com/content/dam/develop/external/us/en/

[TDVF]: https://software.intel.com/content/dam/develop/external/us/en/

Code is at https://github.com/mxu9/edk2/tree/tdvf_wave1.v10

v10 changes:
- Clear the OVMF_WORK_AREA in both ARCH_IA32 and ARCH_X64.
- Update the ReloadFlat32 based on the review comments.
- Other minor changes and update some comments.

v9 changes:
- Introduce IntelTdxMetadata.asm in a separate commit.
- Use absolute offset for the start of TdxMetadata so that VMM can
easily reach to the start of the metadata.

v8 changes:
- Create a separate commit for Main.asm.
- Create a separate commit for the clearance of WORK_AREA_GUEST_TYPE.
- Fix some inaccurate comments.

v7 changes:
- Refine the offset of TdxMetadata and remove the definition of
- Use MOV CR* instead of smsw in ResetVector
- Remove the new field (SubType) in

v6 changes:
- Remove the 5-level paging support. 5-level paging enabling is *NOT*
super critical for TDX enabling at this moment. It will be enabled
later in a separate patch.
to record the VM Guest SubType.
- In Main16 entry point, after TransitionFromReal16To32BitFlat,
previously cleared in SetCr3ForPageTables64 (see commit ab77b60).
This doesn't work after TDX is introduced in Ovmf. It is because all
TDX CPUs (BSP and APs) start to run from 0xfffffff0. In previous code
WORK_AREA_GUEST_TYPE will be cleared multi-times in TDX guest. So for
SEV and Legacy guest it is moved to Main16 entry point (after
TransitionFromReal16To32BitFlat). For TDX guest WORK_AREA_GUEST_TYPE
is cleared and set in InitTdxWorkarea.
- Make the return result of IsTdx be consistent with IsTdxEnabled.
- Fix some typo in the code comments.

v5 changes:
- Remove the changes of OVMF_WORK_AREA because Commit ab77b60 covers
those changes.
- Refine the TDX related changes in PageTables64.asm and
- Add CheckTdxFeaturesBeforeBuildPagetables to check Non-Tdx, Tdx-BSP or
Tdx-APs. This routine is called before building page tables.

v4 changes:
- Refine the PageTables64.asm and Flat32ToFlat64.asm to enable TDX.
- Refine SEV_ES_WORK_AREA so that SEV/TDX/Legach guest all can use this
memory region. https://edk2.groups.io/g/devel/message/78345 is the
- AmdSev.asm is removed because Brijesh Singh has done it in

v3 changes:
- Refine PageTables64.asm and Flat32ToFlat64.asm based on the review
comments in [ReviewComment-1] and [ReviewComment-2].
- SEV codes are in AmdSev.asm
- TDX codes are in IntelTdx.asm
- Main.asm is created in OvmfPkg/ResetVector. The one in
UefiCpuPkg/ResetVector/Vtf0 is not used.
- Init32.asm/ReloadFlat32.asm in UefiCpuPkg/ResetVector/Vtf0/Ia32 are
deleted. They're moved to OvmfPkg/ResetVector/Ia32.
- InitTdx.asm is renamed to InteTdx.asm

v2 changes:
- Move InitTdx.asm and ReloadFlat32.asm from UefiCpuPkg/ResetVector/Vtf0
to OvmfPkg/ResetVector. Init32.asm is created which is a null stub of
32-bit initialization. In Main32 just simply call Init32. It makes
the Main.asm in UefiCpuPkg/ResetVector clean and clear.
- Init32.asm/InitTdx.asm/ReloadFlat32.asm are created under
- Update some descriptions of the patch-sets.
- Update the REF link in cover letter.
- Add Ard Biesheuvel in Cc list.

v1: https://edk2.groups.io/g/devel/message/77675

Cc: Ard Biesheuvel <ardb+tianocore@...>
Cc: Gerd Hoffmann <kraxel@...>
Cc: Jordan Justen <jordan.l.justen@...>
Cc: Brijesh Singh <brijesh.singh@...>
Cc: Erdem Aktas <erdemaktas@...>
Cc: James Bottomley <jejb@...>
Cc: Jiewen Yao <jiewen.yao@...>
Cc: Tom Lendacky <thomas.lendacky@...>
Signed-off-by: Min Xu <min.m.xu@...>

Min Xu (4):
OvmfPkg: Copy Main.asm from UefiCpuPkg to OvmfPkg's ResetVector
OvmfPkg: Clear WORK_AREA_GUEST_TYPE in Main.asm
OvmfPkg: Add IntelTdxMetadata.asm
OvmfPkg: Enable TDX in ResetVector

OvmfPkg/OvmfPkg.dec | 9 +
OvmfPkg/OvmfPkgDefines.fdf.inc | 9 +
OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm | 39 ++++
OvmfPkg/ResetVector/Ia32/Flat32ToFlat64.asm | 11 +
OvmfPkg/ResetVector/Ia32/IntelTdx.asm | 222 +++++++++++++++++++
OvmfPkg/ResetVector/Ia32/PageTables64.asm | 22 +-
OvmfPkg/ResetVector/Main.asm | 121 ++++++++++
OvmfPkg/ResetVector/ResetVector.inf | 9 +
OvmfPkg/ResetVector/ResetVector.nasmb | 28 +++
OvmfPkg/ResetVector/X64/IntelTdxMetadata.asm | 115 ++++++++++
10 files changed, 581 insertions(+), 4 deletions(-)
create mode 100644 OvmfPkg/ResetVector/Ia32/IntelTdx.asm
create mode 100644 OvmfPkg/ResetVector/Main.asm
create mode 100644 OvmfPkg/ResetVector/X64/IntelTdxMetadata.asm


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