** Description changed: SRU Justification: [Impact] A series of upstream arm64 and KVM architecture patches are missing from the Jammy and Noble kernels. These commits correct the early initialization and handling of HCR_EL2.E2H regarding feature detection for FEAT_E2H0 (systems omitting support for running a host at EL1 without Virtualization Host Extensions). The lack of these fixes on Google Cloud Platform (-gcp) kernel running on ARM64 cloud instances can result in unstable KVM state initialization, improper architectural register detection, or boot-time dependency breakages. Because individual patches in the series introduced tightly coupled edge-case bugs that were sequentially resolved by the later commits, the entire sequence must be backported as an atomic block to Noble release. [Fix] Backport the upstream 4-commit sequence that revamps the general HCR_EL2.E2H RES1 detection safely and initializes it early. These patches (already present in the v7.0 base and partially upstreamed to stable branches such as 6.12.64) must be evaluated against the 6.8 (Noble) codebase to cleanly resolve code drift in the early ARM64 CPU boot/setup phases. [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. [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
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2160745 Title: KVM backports to 6.8 related to HCR_EL2.E2H To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-gcp/+bug/2160745/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
