F43 Change Proposal: Confidential Virtualization Host for Intel TDX (self-contained)

Project Discussion Change Proposals
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1

Confidential Virtualization Host for Intel TDX

This is a proposed Change for Fedora Linux.
This document represents a proposed Change. As part of the Changes process, proposals are publicly announced in order to receive community feedback. This proposal will only be implemented if approved by the Fedora Engineering Steering Committee.

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:link: Summary

This change will introduce support for Fedora virtualization hosts to run confidential guests on suitable Intel TDX hardware.

:link: Owner

:link: Detailed Description

Fedora has provided support for launching confidential virtual machines using KVM on x86_64 hosts for several years, using the SEV and SEV-ES technologies available from AMD CPUs, and since Fedora 41, using the SEV-SNP technology. In the Fedora 42 release, support for the Intel SGX platform was introduced, and this change builds on that work to allow creation of Intel TDX guests on Fedora hosts. Intel TDX provides confidential virtualization functionality that is on a par with the recent AMD SEV-SNP support.

:link: Feedback

TBD

:link: Benefit to Fedora

  • This change allows creation of Intel TDX guests on Fedora virtualization hosts when suitable Intel TDX hardware (EmeraldRapids or newer Xeon CPUs) is available

:link: Scope

The vast majority of work will arrive in Fedora automatically via regularly performed rebases to new upstream releases.

  • Proposal owners:

    • Rebase QEMU to 10.1.0 release (GA ~ Sept 1st, release candidates available before Fedora freeze)
    • Rebase libvirt to 11.8.0 release (GA ~ Sept 1st, release candidates, or patch backports, available before Fedora freeze)
    • Write SELinux policy for ā€˜qgsā€™ daemon (qgs_t) to allow QEMU (svirt_t) to talk to it for attestation.
    • Enhance virt-install to allow creation of TDX guests and arrange for new release & rebase, or patch backport

  • Other developers:

    • Rebase kernel to >= 6.16 (TDX host patches targetted for 6.16 merge window in 1st week of April)
    • Merge new SELinux policy rules for ā€˜qgsā€™ daemon and QEMU

  • Release engineering: N/A (not needed for this Change)

  • Policies and guidelines: N/A (not needed for this Change)

  • Trademark approval: N/A (not needed for this Change)

:link: Alignment with the Fedora Strategy

  • Fedora will be demonstrating leading / state of the art integration of Intel TDX feature into a Linux distributionā€™s virtualization host stack.
  • Fedora will be providing the fully OSS host-to-guest stack for confidential virtual machines on modern Intel x86_64 Xeon hardware.

:link: Upgrade/compatibility impact

None expected, the new functionality doesnā€™t impact on existing functionality in Fedora

:link: Early Testing (Optional)

N/A

:link: How To Test

Full details TBD - high level intent is:

  • Check whether the host hardware configuration is capable of supporting TDX (very strict DIMM population requirements, along with EmeraldRapids or newer Xeon class CPUs)
  • Configure EFI firmware to enable use of SGX and TDX
  • Disable hibernation support in host kernel via adding ā€˜nohibernateā€™ to /etc/default/grub and re-creating grub.cfg
  • Use ā€˜virt-installā€™ to provision an confidential VM
  • Request an attestation report from the guest using sysfs
  • Validate the attestation report on a trusted machine using

:link: User Experience

  • Virtualization host owners will be able to launch confidential virtual machines using Intel TDX technology
  • Guest owners will be able to prove that their OS is running in a Fedora host confidential virtual machine protected by Intel TDX, by performing a guest attestation

:link: Dependencies

  • Fedora SELinux maintainers need to review & merge new policy to be submitted by proposal owners for the ā€˜qgsā€™ daemon
  • Fedora kernel maintainers need to rebase to >= 6.16 (should be happening regardless, as normal kernel maint work)
  • virt-install owner to do rebase or accept MR to backport TDX support patches

:link: Contingency Plan

  • Contingency mechanism: Ship whatever was ready in time, and leave rest until Fedora 44
  • Contingency deadline: Change completion deadline
  • Blocks release? No

:link: Documentation

:link: Release Notes

Fedora virtualization hosts running on suitably configured Intel Xeon hardware, have the ability to launch confidential virtual machines using the Intel TDX feature.

Last edited by @amoloney 2025-04-16T14:08:27Z

Last edited by @amoloney 2025-04-16T14:08:27Z

2

How do you feel about the proposal as written?

  • Strongly in favor
  • In favor, with reservations
  • Neutral
  • Opposed, but could be convinced
  • Strongly opposed
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