Linux kernel KVM arm64 vGIC: double-deactivate of nested IRQs trips an AmpereOne erratum

CVE-2026-80699Kernel, userspace & hypervisorcurated

Impact

In the nested state the physical interrupt has already been deactivated through the HW bit in the list register, but KVM deactivated it a second time. Per the record, on AmpereOne deactivating a physical interrupt that is not active but is the highest-priority pending one makes the CPU lose the interrupt pending state and stop delivering future interrupts. On an Arm datacenter host that is a wedged physical CPU and lost interrupt delivery - a node you reboot rather than drain gracefully, which is expensive when it is holding long-running jobs. The exposure is limited to hosts running nested guests on affected Ampere silicon; elsewhere the extra deactivation is described as harmless.

Who can reach it

Local to the host and driven by guest activity: requires nested virtualization enabled and a guest hypervisor producing the interrupt pattern. Not reachable over the network or from a non-virtualized workload.

What to do

Update the host kernel to a stable release containing the fix and reboot each affected host, migrating or draining guests first. Until the reboot window, not enabling nested virtualization on AmpereOne hosts keeps the path out of reach.

References

https://nvd.nist.gov/vuln/detail/CVE-2026-80699 https://git.kernel.org/stable/c/8a570b19b4b16a8a3b5ffa2b332bd5613110b2d8 https://git.kernel.org/stable/c/f78f08b38a7f121c7d6b3e41002d9de7fd3c9189

This entry is curated: imported from vendor advisories with machine assistance, not yet individually verified. Confirm against your vendor's advisory before acting, and report anything wrong.