** Description changed:
SRU Justification:
[Impact]
- Google has requested a backport of some upstream arm64 and KVM architecture
+ Google has requested a backport of some upstream arm64 and KVM architecture
HCR_EL2.E2H related patches to the Noble kernel linux-gcprelease.
[Fix]
Target patches:
3944382fa6f2 ("arm64: Treat HCR_EL2.E2H as RES1 when ID_AA64MMFR4_EL1.E2H0 is
negative")
b3320142f3db ("arm64: Fix early handling of FEAT_E2H0 not being implemented")
7a68b55ff39b ("KVM: arm64: Initialize HCR_EL2.E2H early")
ca88ecdce5f5 ("arm64: Revamp HCR_EL2.E2H RES1 detection")
Some additional patches may be needed for these to apply/build cleanly:
[Test Plan]
- Provision an ARM64-based Instance on Google Cloud Platform running the
- target kernel version (Noble). Validate hardware virtualization
- capability flags and boot log diagnostic buffers via dmesg | grep -i kvm
- or dmesg | grep -i e2h. Verify that the KVM subsystem initializes
- correctly and hypervisor execution states do not throw system traps or
- register state corruptions under immediate host-guest context switching.
- Execute the standard Ubuntu Kernel Regression Test (KRT) suite for
- virtualization topologies on ARM64 architectures.
+ Copile tested
+ Boot test
[Regression potential]
The regression potential is isolated strictly to ARM64 (aarch64)
platforms, with zero risk to x86 or other architectures. Because these
patches alter register initialization logic (HCR_EL2) at very early boot
and hypervisor init stages, regressions could manifest as boot failures,
kernel panics during early CPU feature detection, or broken nested
virtualization on specific ARM hardware implementations. However, this
risk is deeply mitigated by pulling the entire 4-commit sequence as a
comprehensive lifecycle block, directly mirroring stable upstream
patterns (such as those fed by the 6.12 stable branches).
[Other Info]
SF:00442966
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https://bugs.launchpad.net/bugs/2160745
Title:
KVM backports to 6.8 related to HCR_EL2.E2H
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