FreeBSD : xen-tools -- qemu incautious about shared ring processing (58685e23-ba4d-11e6-ae1b-002590263bf5)

The Xen Project reports : The compiler can emit optimizations in qemu which can lead to double fetch vulnerabilities. Specifically data on the rings shared between qemu and the hypervisor which the guest under control can obtain mappings of can be fetched twice during which time the guest can alt...