[ Please CC me on replies as I'm not subscribed to this list. ] Hi
The Fix for CVE-2016-5403 (virtio: error out if guest exceeds virtqueue size)[1] causes qemu to exit(1) after migration or restart from a saved state if memory statistics are enabled in libvirt. Qemu exits after printing "qemu-system-x86_64: Virtqueue size exceeded". I experienced this problem with the latest security update in Ubuntu Trusty (14.04) which cherry-picked this fix. If you think that the latest upstream version is not affected I can try this too. I only tested with VM started through libvirt. If someone tells me how to enable memory statistics with plain qemu without libvirt I can test this too. My guess would be that this does not make a difference. I discovered this bug because OpenStack Nova enables memory statistics by default since the Juno release. After the QEMU upgrade to the latest version in Ubuntu VMs were suddenly shutoff after migration. Steps to reproduce: 1. Create a VM with libvirt which contains a memory balloon device defined like this: <memballoon model='virtio'> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> <stats period='10'/> </memballoon> 2. Start the VM and let the Linux kernel boot (bug does not appear if the kernel is not yet booted, eg. while in the PXE boot phase) 3. Issue a managedsave 4. Start the VM again 5. The VM is restored and "crashes" right after it starts running again. 6. You can find the qemu output "qemu-system-x86_64: Virtqueue size exceeded" in the log at /var/log/libvirt/vmname.log Gaudenz [1] https://lists.gnu.org/archive/html/qemu-devel/2016-07/msg06257.html
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