two security flaws (#1406840)
    x86 PV guests may be able to mask interrupts [XSA-202, CVE-2016-10024]
    x86: missing NULL pointer check in VMFUNC emulation [XSA-203, CVE-2016-10025]
    x86: Mishandling of SYSCALL singlestep during emulation [XSA-204,
    	CVE-2016-10013] (#1406260)