On 09/20/2017 06:04 PM, Dr. David Alan Gilbert wrote: > * Christian Borntraeger (borntrae...@de.ibm.com) wrote: >> Something like the following seems to do the tricks. >> Needs proper patch description, review, full test with different kernel >> versions..... > > Without knowing anything about 'ais' - will this break migration from > 2.10 -> 2.10+this fix?
The problem only happens if the source system has kernel >= 4.12 thats why it somehow missed my testing during the 2.10 freeze. Now: "2.10" -> "2.10+this fix" will works fine for the 2.10 machine, but it does fail for the combination of qemu-2.10 with an older machine type like 2.8 and 2.9. qemu-system-s390x: Failed to load s390-flic/ais:tmp qemu-system-s390x: error while loading state for instance 0x0 of device 's390-flic' qemu-system-s390x: load of migration failed: Function not implemented We do run into an explicit check from hw/intc/s390_flic_kvm.c (see the return ENOSYS) e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 443) static int kvm_flic_ais_post_load(void *opaque, int version_id) e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 444) { e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 445) KVMS390FLICStateMigTmp *tmp = opaque; e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 446) KVMS390FLICState *flic = tmp->parent; e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 447) struct kvm_s390_ais_all ais = { e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 448) .simm = tmp->simm, e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 449) .nimm = tmp->nimm, e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 450) }; e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 451) struct kvm_device_attr attr = { e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 452) .group = KVM_DEV_FLIC_AISM_ALL, e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 453) .addr = (uint64_t)&ais, e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 454) }; e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 455) e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 456) /* This can happen when the user mis-configures its guests in an e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 457) * incompatible fashion or without a CPU model. For example using e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 458) * qemu with -cpu host (which is not migration safe) and do a e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 459) * migration from a host that has AIS to a host that has no AIS. e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 460) * In that case the target system will reject the migration here. e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 461) */ e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 462) if (!ais_needed(flic)) { e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 463) return -ENOSYS; e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 464) } e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 465) e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 466) return ioctl(flic->fd, KVM_SET_DEVICE_ATTR, &attr) ? -errno : 0; e7be8d49 (Yi Min Zhao 2017-05-16 18:58:44 +0800 467) } So I think if we fix this we should definitely add this to 2.10.1 to minimize the affected qemu versions. Not fixing it will break migrations from 4.12/2.10 to older versions. > > Dave > >> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c >> index 1c7af39..2ff32ba 100644 >> --- a/hw/s390x/s390-virtio-ccw.c >> +++ b/hw/s390x/s390-virtio-ccw.c >> @@ -212,6 +212,7 @@ static void ccw_machine_class_init(ObjectClass *oc, void >> *data) >> s390mc->cpu_model_allowed = true; >> s390mc->css_migration_enabled = true; >> s390mc->gs_allowed = true; >> + s390mc->ais_allowed = true; >> mc->init = ccw_init; >> mc->reset = s390_machine_reset; >> mc->hot_add_cpu = s390_hot_add_cpu; >> @@ -305,6 +306,11 @@ bool gs_allowed(void) >> return false; >> } >> >> +bool ais_allowed(void) >> +{ >> + return get_machine_class()->ais_allowed; >> +} >> + >> static char *machine_get_loadparm(Object *obj, Error **errp) >> { >> S390CcwMachineState *ms = S390_CCW_MACHINE(obj); >> @@ -533,6 +539,7 @@ static void ccw_machine_2_9_class_options(MachineClass >> *mc) >> S390CcwMachineClass *s390mc = S390_MACHINE_CLASS(mc); >> >> s390mc->gs_allowed = false; >> + s390mc->ais_allowed = false; >> ccw_machine_2_10_class_options(mc); >> SET_MACHINE_COMPAT(mc, CCW_COMPAT_2_9); >> s390mc->css_migration_enabled = false; >> diff --git a/include/hw/s390x/s390-virtio-ccw.h >> b/include/hw/s390x/s390-virtio-ccw.h >> index 41a9d28..bba8660 100644 >> --- a/include/hw/s390x/s390-virtio-ccw.h >> +++ b/include/hw/s390x/s390-virtio-ccw.h >> @@ -41,6 +41,7 @@ typedef struct S390CcwMachineClass { >> bool cpu_model_allowed; >> bool css_migration_enabled; >> bool gs_allowed; >> + bool ais_allowed; >> } S390CcwMachineClass; >> >> /* runtime-instrumentation allowed by the machine */ >> @@ -49,6 +50,8 @@ bool ri_allowed(void); >> bool cpu_model_allowed(void); >> /* guarded-storage allowed by the machine */ >> bool gs_allowed(void); >> +/* ais allowed by the machine */ >> +bool ais_allowed(void); >> >> /** >> * Returns true if (vmstate based) migration of the channel subsystem >> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c >> index c4c5791..531d474 100644 >> --- a/target/s390x/kvm.c >> +++ b/target/s390x/kvm.c >> @@ -309,7 +309,9 @@ int kvm_arch_init(MachineState *ms, KVMState *s) >> } >> >> /* Try to enable AIS facility */ >> - kvm_vm_enable_cap(s, KVM_CAP_S390_AIS, 0); >> + if (ais_allowed()) { >> + kvm_vm_enable_cap(s, KVM_CAP_S390_AIS, 0); >> + } >> >> qemu_mutex_init(&qemu_sigp_mutex); >> >> > -- > Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK >