On 11/11/2015 10:09, Andrey Smetanin wrote: >> >> I would prefer to put this in kvm_arch_init_vcpu, if possible. >> > Ok. I think the kvm_arch_init_vcpu() is called after migration restores > cpu->env->msr_hv_synic_* values, so unconditional initialization of > cpu->env->msr_hv_synic_* values can overwrite migrated values. The check > "if (!env->msr_hv_synic_version) {" is neccessary for first time > initialization to protect against such overwriting. This is why this > code migrates 'msr_hv_synic_version' value. No, kvm_arch_init_vcpu is called at the very beginning, when the VCPU thread is created. main -> machine_class->init -> pc_init1 -> pc_cpus_init -> pc_new_cpu -> cpu_x86_create -> object_property_set_bool -> x86_cpu_realizefn -> qemu_init_vcpu -> qemu_kvm_start_vcpu -> qemu_kvm_cpu_thread_fn (in new thread) -> kvm_init_vcpu -> kvm_arch_init_vcpu This is long before qemu_start_incoming_migration, which is among the last things done before calling main_loop Paolo -- 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