Repro: macOS 26 (Tahoe), M4 Max. Idle RHEL 10 aarch64 guest booted under qemu-system-aarch64 -machine virt -accel hvf -cpu host -smp 4 -m 2G. Guest reports loadavg 0.2, /proc/stat 99% idle; host ps -M shows each vCPU thread at ~50% Running. Downgrading QEMU to 10.2.2 restores ~1.5% host CPU per VM, same guest image and args. Machine-version pinning (virt-10.2) on 11.0.0 does not help — the regression lives in version-wide HVF accel code, not board defaults. Suspect: b5f8f772 ("accel/hvf: Implement WFI without using pselect()") — the rewrite replaced per-vCPU pselect sleep with "return to main loop." On aarch64 HVF the main-loop wake path appears to not actually block an idle vCPU thread.