[Bug 2143146] [NEW] [Ubuntu 26.04] New HWE stack for Ubuntu virtualization components

[Hector CAO]

Public bug reported:

Dear Release Team,

We request approval for a Feature Freeze Exception (FFE) to introduce a
new Hardware Enablement (HWE) userspace virtualization stack for Ubuntu
26.04 LTS, consisting of -hwe-suffixed packages for the core
virtualization components:

- qemu
- libvirt
- edk2
- seabios)

[Rationale]

Modern hardware-assisted virtualization and confidential computing
technologies evolve at a pace closely tied to CPU and platform
innovation, significantly faster than the Ubuntu LTS release cadence. At
the same time, production virtualization deployments overwhelmingly rely
on Ubuntu LTS releases, creating a gap between available hardware
capabilities and the software stack provided by a stable LTS.

This FFE proposes a rolling userspace HWE virtualization stack,
conceptually aligned with the existing kernel HWE model. Over the
lifetime of Ubuntu 26.04 LTS, the -hwe virtualization stack would be
updated—via a dedicated SRU exception—to track the versions shipped in
subsequent Ubuntu releases. This allows LTS users to access new
virtualization and confidential-computing features without upgrading to
a non-LTS release.

This approach enables:

- Ongoing support for new virtualization features throughout the LTS
lifecycle

- Enablement of new hardware and CPU capabilities as they become
available

- Timely delivery of critical virtualization functionality without
waiting for the next LTS

- Consistent platform enablement by aligning userspace virtualization
with the kernel HWE strategy

The -base and -hwe stacks will coexist but be mutually exclusive at
install time, allowing users to explicitly choose between maximum
stability (base) and newer feature enablement (hwe).

[Scope of Changes]

The following new source packages will be introduced:

qemu-hwe (from qemu)

libvirt-hwe (from libvirt)

edk2-hwe (from edk2)

seabios-hwe (from seabios)

At Ubuntu 26.04 release time, the -hwe packages will be functionally
identical to the -base packages. Divergence will occur only after the
Ubuntu 26.10 release, at which point the -hwe stack will begin tracking
newer upstream versions via an approved SRU exception process.

[Content]

PPA: TBD

Code branches (to be created):
- qemu-hwe: https://code.launchpad.net/~ubuntu-virt/ubuntu/+source/qemu-hwe
- libvirt-hwe: https://code.launchpad.net/~ubuntu-virt/ubuntu/+source/libvirt-hwe
- edk2-hwe: https://code.launchpad.net/~ubuntu-virt/ubuntu/+source/edk2-hwe
- seabios-hwe: https://code.launchpad.net/~ubuntu-virt/ubuntu/+source/seabios-hwe

Autopkgtest results available at the PPA.

[Testing Performed]

Build testing:
- All packages successfully built on amd64, arm64, armhf, ppc64el, s390x, riscv64
- Build logs available in PPA
- No new build warnings or errors introduced

Testing of the switch between stacks:
- TBD

Upgrade testing:
- Upgrade from qemu-base to qemu-hwe (removing base, installing hwe): TODO
- Downgrade from qemu-hwe to qemu-base: TODO
- Verified existing VM configurations remain functional after stack switch (TODO)

[Regression Potential]

The proposed change is fully opt-in, and therefore poses low risk to
existing users who remain on the -base stack. However, the introduction
of a parallel virtualization stack does increase maintenance and testing
complexity.

Potential regression risks include:

 - Package conflicts or dependency issues in the -hwe stack

 - Incompatibilities with older components outside the -hwe scope

 - Configuration handling issues when switching between stacks,
including loss of state or inability to revert cleanly

 - Regressions introduced by future SRU updates as the -hwe stack tracks
newer releases

These risks are mitigated by:

 - Explicit user opt-in

 - Mutual exclusivity between -base and -hwe packages

 - A dedicated SRU exception with enhanced review and testing
requirements

[Seeded Packages]

None is auto-installed, but some might be on the repo for offline
install.

** Affects: ubuntu
     Importance: High
         Status: New

** Affects: edk2 (Ubuntu)
     Importance: High
         Status: New

** Affects: libvirt (Ubuntu)
     Importance: High
         Status: New

** Affects: qemu (Ubuntu)
     Importance: High
         Status: New

** Affects: seabios (Ubuntu)
     Importance: High
         Status: New

** Also affects: qemu (Ubuntu)
   Importance: Undecided
       Status: New

** Also affects: libvirt (Ubuntu)
   Importance: Undecided
       Status: New

** Also affects: edk2 (Ubuntu)
   Importance: Undecided
       Status: New

** Also affects: seabios (Ubuntu)
   Importance: Undecided
       Status: New

** Changed in: edk2 (Ubuntu)
   Importance: Undecided => High

** Changed in: qemu (Ubuntu)
   Importance: Undecided => High

** Changed in: seabios (Ubuntu)
   Importance: Undecided => High

** Changed in: libvirt (Ubuntu)
   Importance: Undecided => High

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https://bugs.launchpad.net/bugs/2143146

Title:
  [Ubuntu 26.04] New HWE stack for Ubuntu virtualization components

Status in Ubuntu:
  New
Status in edk2 package in Ubuntu:
  New
Status in libvirt package in Ubuntu:
  New
Status in qemu package in Ubuntu:
  New
Status in seabios package in Ubuntu:
  New

Bug description:
  Dear Release Team,

  We request approval for a Feature Freeze Exception (FFE) to introduce
  a new Hardware Enablement (HWE) userspace virtualization stack for
  Ubuntu 26.04 LTS, consisting of -hwe-suffixed packages for the core
  virtualization components:

  - qemu
  - libvirt
  - edk2
  - seabios)

  [Rationale]

  Modern hardware-assisted virtualization and confidential computing
  technologies evolve at a pace closely tied to CPU and platform
  innovation, significantly faster than the Ubuntu LTS release cadence.
  At the same time, production virtualization deployments overwhelmingly
  rely on Ubuntu LTS releases, creating a gap between available hardware
  capabilities and the software stack provided by a stable LTS.

  This FFE proposes a rolling userspace HWE virtualization stack,
  conceptually aligned with the existing kernel HWE model. Over the
  lifetime of Ubuntu 26.04 LTS, the -hwe virtualization stack would be
  updated—via a dedicated SRU exception—to track the versions shipped in
  subsequent Ubuntu releases. This allows LTS users to access new
  virtualization and confidential-computing features without upgrading
  to a non-LTS release.

  This approach enables:

  - Ongoing support for new virtualization features throughout the LTS
  lifecycle

  - Enablement of new hardware and CPU capabilities as they become
  available

  - Timely delivery of critical virtualization functionality without
  waiting for the next LTS

  - Consistent platform enablement by aligning userspace virtualization
  with the kernel HWE strategy

  The -base and -hwe stacks will coexist but be mutually exclusive at
  install time, allowing users to explicitly choose between maximum
  stability (base) and newer feature enablement (hwe).

  [Scope of Changes]

  The following new source packages will be introduced:

  qemu-hwe (from qemu)

  libvirt-hwe (from libvirt)

  edk2-hwe (from edk2)

  seabios-hwe (from seabios)

  At Ubuntu 26.04 release time, the -hwe packages will be functionally
  identical to the -base packages. Divergence will occur only after the
  Ubuntu 26.10 release, at which point the -hwe stack will begin
  tracking newer upstream versions via an approved SRU exception
  process.

  [Content]

  PPA: TBD

  Code branches (to be created):
  - qemu-hwe: https://code.launchpad.net/~ubuntu-virt/ubuntu/+source/qemu-hwe
  - libvirt-hwe: https://code.launchpad.net/~ubuntu-virt/ubuntu/+source/libvirt-hwe
  - edk2-hwe: https://code.launchpad.net/~ubuntu-virt/ubuntu/+source/edk2-hwe
  - seabios-hwe: https://code.launchpad.net/~ubuntu-virt/ubuntu/+source/seabios-hwe

  Autopkgtest results available at the PPA.

  [Testing Performed]

  Build testing:
  - All packages successfully built on amd64, arm64, armhf, ppc64el, s390x, riscv64
  - Build logs available in PPA
  - No new build warnings or errors introduced

  Testing of the switch between stacks:
  - TBD

  Upgrade testing:
  - Upgrade from qemu-base to qemu-hwe (removing base, installing hwe): TODO
  - Downgrade from qemu-hwe to qemu-base: TODO
  - Verified existing VM configurations remain functional after stack switch (TODO)

  [Regression Potential]

  The proposed change is fully opt-in, and therefore poses low risk to
  existing users who remain on the -base stack. However, the
  introduction of a parallel virtualization stack does increase
  maintenance and testing complexity.

  Potential regression risks include:

   - Package conflicts or dependency issues in the -hwe stack

   - Incompatibilities with older components outside the -hwe scope

   - Configuration handling issues when switching between stacks,
  including loss of state or inability to revert cleanly

   - Regressions introduced by future SRU updates as the -hwe stack
  tracks newer releases

  These risks are mitigated by:

   - Explicit user opt-in

   - Mutual exclusivity between -base and -hwe packages

   - A dedicated SRU exception with enhanced review and testing
  requirements

  [Seeded Packages]

  None is auto-installed, but some might be on the repo for offline
  install.

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