QEMU console becomes unresponsive

[Christoffer Dall]

When running QEMU using KVM and the -nographics option using the default pl011 emulation, some times the console does not receive input from the keyboard. This happens something like 1 in 10 executions, and shows up quite clearly when suspending the VM and resuming them (logic for this is not upstream yet.

Kernel version 3.10 or later and upstream QEMU reproduces this issue.

Use the following QEMU command line options to reproduce:

./qemu-system-arm -s \
        -smp 2 -m 512 \
        -cpu cortex-a15 \
        -machine type=vexpress-a15, \
        -kernel zImage -dtb vexpress-v2p-ca15-tc1.dtb \
        -enable-kvm \
        -drive if=none,file=ubuntu.img,id=foo \
        -device virtio-blk-device,drive=foo \
        -netdev tap,id=tap0 \
        -device virtio-net-device,netdev=tap0 \
        -nographic \
        -append 'root=/dev/vda rw console=ttyAMA0 rootwait earlyprintk'