This update includes several patches for Xen that are backported from changes in the Linux 4.9 and 4.10 kernel releases. Many of these patches improve performance, error handling and provide general bug fixes. Other notable fixes and improvements include the following:

• A fix has been applied to the Xen blkfront driver to resolve a race condition that could cause I/O to hang when the ring buffer was full and the hardware queue was stopped.

• A fix has been applied to the Xen blkback driver to update the xenstore node hotplug status to provide notification of a busy block device that cannot be detached because it is mounted inside a guest. This can prevent block-detach hangs when detaching a block device that is in use.

• Performance enhancements were introduced in the Xen netback and netfront drivers to improve network throughput on chatty network activities that stress IRQ processing. This can enhance database performance in a virtual machine to more closely match the performance on bare metal. Other netback and netfront driver fixes were also applied to improve handling for network stress

• An update of the Xen PCIfront driver is available, which supports vNUMA functionality so that a guest can mark specific PCI devices as belonging to NUMA nodes.