• Paolo Bonzini's avatar
    Merge branch 'cve-2019-3016' into kvm-next-5.6 · 4cbc418a
    Paolo Bonzini authored
    From Boris Ostrovsky:
    
    The KVM hypervisor may provide a guest with ability to defer remote TLB
    flush when the remote VCPU is not running. When this feature is used,
    the TLB flush will happen only when the remote VPCU is scheduled to run
    again. This will avoid unnecessary (and expensive) IPIs.
    
    Under certain circumstances, when a guest initiates such deferred action,
    the hypervisor may miss the request. It is also possible that the guest
    may mistakenly assume that it has already marked remote VCPU as needing
    a flush when in fact that request had already been processed by the
    hypervisor. In both cases this will result in an invalid translation
    being present in a vCPU, potentially allowing accesses to memory locations
    in that guest's address space that should not be accessible.
    
    Note that only intra-guest memory is vulnerable.
    
    The five patches address both of these problems:
    1. The first patch makes sure the hypervisor doesn't accidentally clear
    a guest's remote flush request
    2. The rest of the patches prevent the race between hypervisor
    acknowledging a remote flush request and guest issuing a new one.
    
    Conflicts:
    	arch/x86/kvm/x86.c [move from kvm_arch_vcpu_free to kvm_arch_vcpu_destroy]
    4cbc418a
x86.c 272 KB