The AIS feature has been disabled late in the v2.10 development cycle since there were some issues with migration (see commit 3f2d07b3b01ea61126b - "s390x/ais: for 2.10 stable: disable ais facility"). We originally wanted to enable it again for newer machine types, but apparently we forgot to do this so far. Let's do it for the new s390-ccw-virtio-5.0 machine now.
While at it, also add a more verbose comment why we need the *_allowed() wrappers in s390-virtio-ccw.c. Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1756946 Reviewed-by: David Hildenbrand <da...@redhat.com> Signed-off-by: Thomas Huth <th...@redhat.com> --- v3: Moved "s390mc->kvm_ais_allowed = false" to the end of the function hw/s390x/s390-virtio-ccw.c | 20 +++++++++++++++++--- include/hw/s390x/s390-virtio-ccw.h | 3 +++ target/s390x/kvm.c | 9 ++++++--- 3 files changed, 26 insertions(+), 6 deletions(-) diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c index e0e28139a2..76254e8447 100644 --- a/hw/s390x/s390-virtio-ccw.c +++ b/hw/s390x/s390-virtio-ccw.c @@ -452,6 +452,7 @@ static void ccw_machine_class_init(ObjectClass *oc, void *data) s390mc->cpu_model_allowed = true; s390mc->css_migration_enabled = true; s390mc->hpage_1m_allowed = true; + s390mc->kvm_ais_allowed = true; mc->init = ccw_init; mc->reset = s390_machine_reset; mc->hot_add_cpu = s390_hot_add_cpu; @@ -505,6 +506,14 @@ static inline void machine_set_dea_key_wrap(Object *obj, bool value, static S390CcwMachineClass *current_mc; +/* + * Get the class of the s390-ccw-virtio machine that is currently in use. + * Note: libvirt is using the "none" machine to probe for the features of the + * host CPU, so in case this is called with the "none" machine, the function + * returns the TYPE_S390_CCW_MACHINE base class. In this base class, all the + * various "*_allowed" variables are enabled, so that the *_allowed() wrappers + * below return the correct default value for the "none" machine. + */ static S390CcwMachineClass *get_machine_class(void) { if (unlikely(!current_mc)) { @@ -521,22 +530,24 @@ static S390CcwMachineClass *get_machine_class(void) bool ri_allowed(void) { - /* for "none" machine this results in true */ return get_machine_class()->ri_allowed; } bool cpu_model_allowed(void) { - /* for "none" machine this results in true */ return get_machine_class()->cpu_model_allowed; } bool hpage_1m_allowed(void) { - /* for "none" machine this results in true */ return get_machine_class()->hpage_1m_allowed; } +bool kvm_ais_allowed(void) +{ + return get_machine_class()->kvm_ais_allowed; +} + static char *machine_get_loadparm(Object *obj, Error **errp) { S390CcwMachineState *ms = S390_CCW_MACHINE(obj); @@ -658,8 +669,11 @@ static void ccw_machine_4_2_instance_options(MachineState *machine) static void ccw_machine_4_2_class_options(MachineClass *mc) { + S390CcwMachineClass *s390mc = S390_MACHINE_CLASS(mc); + ccw_machine_5_0_class_options(mc); compat_props_add(mc->compat_props, hw_compat_4_2, hw_compat_4_2_len); + s390mc->kvm_ais_allowed = false; } DEFINE_CCW_MACHINE(4_2, "4.2", false); diff --git a/include/hw/s390x/s390-virtio-ccw.h b/include/hw/s390x/s390-virtio-ccw.h index 8aa27199c9..e3ba3b88b1 100644 --- a/include/hw/s390x/s390-virtio-ccw.h +++ b/include/hw/s390x/s390-virtio-ccw.h @@ -40,6 +40,7 @@ typedef struct S390CcwMachineClass { bool cpu_model_allowed; bool css_migration_enabled; bool hpage_1m_allowed; + bool kvm_ais_allowed; } S390CcwMachineClass; /* runtime-instrumentation allowed by the machine */ @@ -48,6 +49,8 @@ bool ri_allowed(void); bool cpu_model_allowed(void); /* 1M huge page mappings allowed by the machine */ bool hpage_1m_allowed(void); +/* adapter-interrupt suppression allowed by the machine? */ +bool kvm_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 15260aeb9a..cf4fb4f2d9 100644 --- a/target/s390x/kvm.c +++ b/target/s390x/kvm.c @@ -365,10 +365,13 @@ int kvm_arch_init(MachineState *ms, KVMState *s) /* * The migration interface for ais was introduced with kernel 4.13 * but the capability itself had been active since 4.12. As migration - * support is considered necessary let's disable ais in the 2.10 - * machine. + * support is considered necessary, we only try to enable this for + * newer machine types if KVM_CAP_S390_AIS_MIGRATION is available. */ - /* kvm_vm_enable_cap(s, KVM_CAP_S390_AIS, 0); */ + if (kvm_ais_allowed() && + kvm_check_extension(s, KVM_CAP_S390_AIS_MIGRATION)) { + kvm_vm_enable_cap(s, KVM_CAP_S390_AIS, 0); + } kvm_set_max_memslot_size(KVM_SLOT_MAX_BYTES); return 0; -- 2.18.1
