KVM: hlt emulation should take in-kernel APIC/PIT timers into account
Timers that fire between guest hlt and vcpu_block's add_wait_queue() are ignored, possibly resulting in hangs. Also make sure that atomic_inc and waitqueue_active tests happen in the specified order, otherwise the following race is open: CPU0 CPU1 if (waitqueue_active(wq)) add_wait_queue() if (!atomic_read(pit_timer->pending)) schedule() atomic_inc(pit_timer->pending) Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
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Avi Kivity

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3d80840d96
@@ -325,6 +325,11 @@ int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu)
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return rc;
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}
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int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
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{
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return 0;
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}
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int kvm_s390_handle_wait(struct kvm_vcpu *vcpu)
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{
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u64 now, sltime;
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