On Sat, Dec 3, 2011 at 2:26 AM, Jan Kiszka <jan.kiszka@xxxxxxxxxxx> wrote: > On 2011-12-02 07:26, Liu Ping Fan wrote: >> From: Liu Ping Fan <pingfank@xxxxxxxxxxxxxxxxxx> >> >> Currently, vcpu can be destructed only when kvm instance destroyed. >> Change this to vcpu's destruction taken when its refcnt is zero, >> and then vcpu MUST and CAN be destroyed before kvm's destroy. > > I'm lacking the big picture yet (would be good to have in the change log > - at least I'm too lazy to read the code): > > What increments the refcnt, what decrements it again? IOW, how does user > space controls the life-cycle of a vcpu after your changes? > In local APIC mode, delivering IPI to target APIC, target's refcnt is incremented, and decremented when finished. At other times, using RCU to protect the vcpu's reference from its destruction. If kvm_vcpu is not needed by guest, user space can close the kvm_vcpu's file descriptors, and then,if the kvm_vcpu has crossed the period of local APCI mode's reference,it will be destroyed. Regards, ping fan > Thanks, > Jan > > -- > Siemens AG, Corporate Technology, CT T DE IT 1 > Corporate Competence Center Embedded Linux -- 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
