audk/OvmfPkg/IntelTdx

TDVF Overview

-------------



<b>Intel Trust Domain Extension (TDX)</b> is Intel Architecture extension

to provide trusted, isolated VM execution by removing CSP software

(hypervisor etc) from the TCB. <b>TDX Virtual Firmware (TDVF)</b> is an

EDK II based project to enable UEFI support for TDX based Virtual

Machines. It provides the capability to launch a TD.



The <b>Intel? TDX Virtual Firmware Design Guide</b> is at

https://www.intel.com/content/dam/develop/external/us/en/documents/tdx-virtual-firmware-design-guide-rev-1.01.pdf.



More information can be found at:

https://www.intel.com/content/www/us/en/developer/articles/technical/intel-trust-domain-extensions.html





Configurations and Features

----------------------------



There are 2 configurations for TDVF.



<b>Config-A:</b>

 - Merge the *basic* TDVF feature to existing OvmfX64Pkg.dsc. (Align

   with existing SEV)

 - Threat model: VMM is NOT out of TCB. (We don?t make things worse)

 - The OvmfX64Pkg.dsc includes SEV/TDX/normal OVMF basic boot capability.

   The final binary can run on SEV/TDX/normal OVMF.

 - No changes to existing OvmfPkgX64 image layout.

 - No need to add additional security features if they do not exist today.

 - No need to remove features if they exist today.

 - RTMR is not supported.

 - PEI phase is NOT skipped in either Td or Non-Td.



<b>Config-B:</b>

 - (*) Add a standalone IntelTdx.dsc to a TDX specific directory for a *full*

   feature TDVF.(Align with existing SEV)

 - (*) Threat model: VMM is out of TCB. (We need necessary change to prevent

   attack from VMM)

 - (*) IntelTdx.dsc includes TDX/normal OVMF basic boot capability. The final

   binary can run on TDX/normal OVMF.

 - It might eventually merge with AmdSev.dsc, but NOT at this point of

   time. And we don?t know when it will happen. We need sync with AMD in

   the community after both of us think the solutions are mature to merge.

 - Need to add necessary security feature as mandatory requirement, such

   as RTMR based Trusted Boot support.

 - Need to measure the external input from Host VMM, such as TdHob, CFV.

 - Need to measure other external input, such as FW_CFG data, os loader,

   initrd, etc.

 - Need to remove unnecessary attack surfaces, such as network stack.



In current stage, <b>Config-A</b> has been merged into edk2-master branch.

The corresponding pkg file is OvmfPkg/OvmfPkgX64.dsc.



<b>Config-B</b> is split into several waves. The corresponding pkg file is

OvmfPkg/IntelTdx/IntelTdxX64.dsc. The features with (*) have been implemented

and merged into edk2-master branch. Others are in upstreaming progress.



Build

------

- Build the TDVF (Config-A) target:

`cd /path/to/edk2`

`source edksetup.sh`

`build.sh -p OvmfPkg/OvmfPkgX64.dsc -a X64 -t GCC5`



- Build the TDVF (Config-B) target:

`cd /path/to/edk2`

`set PACKAGES_PATH=/path/to/edk2/OvmfPkg`

`source edksetup.sh`

`build.sh -p OvmfPkg/IntelTdx/IntelTdxX64.dsc -a X64 -t GCC5`



Usage

-----



Assuming TDX-QEMU/TDX-KVM are already built, one can start a TD virtual

machine as [launching-td-guest](https://github.com/intel/qemu-tdx/blob/tdx-qemu-upstream-rfc-v3/docs/system/i386/tdx.rst#launching-a-td-tdx-vm):



`qemu_system_x86 \`

`   -machine ...,confidential-guest-support=tdx0 \`

`   -object tdx-guest,id=tdx0,[sept-ve-disable=off] \`

`   -drive if=pflash,format=raw,unit=0,file=/path/to/OVMF_CODE.fd \`

`   -drive if=pflash,format=raw,unit=1,file=/path/to/OVMF_VARS.fd \`



Note:

TDX-QEMU/TDX-KVM are still in upstreaming progress. Please refer to:

 - kvm  : https://github.com/intel/tdx/tree/kvm-upstream

 - qemu : https://github.com/intel/qemu-tdx/blob/tdx-qemu-upstream-rfc-v3



Once above 2 upstreaming are completed a minimum qemu/kvm version will be updated here.