• Marcelo Tosatti's avatar
    KVM: PIT: fix injection logic and count · 3cf57fed
    Marcelo Tosatti authored
    The PIT injection logic is problematic under the following cases:
    
    1) If there is a higher priority vector to be delivered by the time
    kvm_pit_timer_intr_post is invoked ps->inject_pending won't be set.
    This opens the possibility for missing many PIT event injections (say if
    guest executes hlt at this point).
    
    2) ps->inject_pending is racy with more than two vcpus. Since there's no locking
    around read/dec of pt->pending, two vcpu's can inject two interrupts for a single
    pt->pending count.
    
    Fix 1 by using an irq ack notifier: only reinject when the previous irq
    has been acked. Fix 2 with appropriate locking around manipulation of
    pending count and irq_ack by the injection / ack paths.
    Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
    Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
    3cf57fed
i8254.h 1.36 KB