On 10/21/15 2:46 PM, Paolo Bonzini wrote:
On 21/10/2015 00:57, Wanpeng Li wrote:kvm_sched_out and kvm_sched_in are part of KVM's preemption hooks. The hooks are registered only between vcpu_load and vcpu_put, therefore they know that the mutex is taken. The sequence will go like this: vcpu_load kvm_sched_out kvm_sched_in kvm_sched_out kvm_sched_in ... vcpu_putIf this should be: vcpu_load kvm_sched_in kvm_sched_out kvm_sched_in kvm_sched_out ... vcpu_putNo, because vcpu_load is called while the thread is running. Therefore, the first preempt notifier call will be a sched_out notification, which calls kvm_arch_vcpu_put. Extending the picture above: vcpu_load -> kvm_arch_vcpu_load kvm_sched_out -> kvm_arch_vcpu_put kvm_sched_in -> kvm_arch_vcpu_load kvm_sched_out -> kvm_arch_vcpu_put kvm_sched_in -> kvm_arch_vcpu_load ... kvm_sched_out -> kvm_arch_vcpu_put kvm_sched_in -> kvm_arch_vcpu_load vcpu_put -> kvm_arch_vcpu_put
Got it, thanks. :-) Regards, Wanpeng Li -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
