xen: various flaws (#1685577)
    grant table transfer issues on large hosts [XSA-284]
    race with pass-through device hotplug [XSA-285]
    x86: steal_page violates page_struct access discipline [XSA-287]
    x86: Inconsistent PV IOMMU discipline [XSA-288]
    missing preemption in x86 PV page table unvalidation [XSA-290]
    x86/PV: page type reference counting issue with failed IOMMU update [XSA-291]
    x86: insufficient TLB flushing when using PCID [XSA-292]
    x86: PV kernel context switch corruption [XSA-293]
    x86 shadow: Insufficient TLB flushing when using PCID [XSA-294]