10 security updates
    
    x86 pv: Crash when handling guest access to MSR_MISC_ENABLE [XSA-333,
    	CVE-2020-25602]
    Missing unlock in XENMEM_acquire_resource error path [XSA-334,
    	CVE-2020-25598]
    race when migrating timers between x86 HVM vCPU-s [XSA-336,
    	CVE-2020-25604]
    PCI passthrough code reading back hardware registers [XSA-337,
    	CVE-2020-25595]
    once valid event channels may not turn invalid [XSA-338, CVE-2020-25597]
    x86 pv guest kernel DoS via SYSENTER [XSA-339, CVE-2020-25596]
    Missing memory barriers when accessing/allocating an event channel [XSA-340,
    	CVE-2020-25603]
    out of bounds event channels available to 32-bit x86 domains [XSA-342,
    	CVE-2020-25600]
    races with evtchn_reset() [XSA-343, CVE-2020-25599]
    lack of preemption in evtchn_reset() / evtchn_destroy() [XSA-344,
    	CVE-2020-25601]