Comment 9 for bug 1851062

I just ran into what I think is the same issue. Windows 10 VM controlled from virt-manager using ~30% CPU while paused.

I'm attaching the output of
pidstat -p $(pidof qemu-system-x86_64) -T ALL -rtuw 5 5
and the first thousand lines of
strace -rT -ff -f -o paused-but-busy -p $(pidof qemu-system-x86_64)
that you requested from the other reporter. As a non-expert, the repeated calls to ioctl(10, KVM_IRQ_LINE_STATUS, ...)+ppoll() timeout seem suggestive to me.

Note: I'm omitting strace for all threads except the one consuming the CPU, since they each contain a single futex() call. If you'd like to see the futex addr/val, let me know.

Thanks for investigating,
Kevin

Full disclosure: I'm using Debian rather than Ubuntu. If you'd like me to repro using the Ubuntu package versions (or on a fully Ubuntu system) I can give it a shot. Currently using qemu-system-x86 1:5.0-5, libvirt 6.0.0-6, and virt-manager 1:2.2.1-4.