On Mon, 20 Jan 2020 14:24:41 +0100 Thomas Huth <th...@redhat.com> wrote:
> 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/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)) { Hnm, we actually need a kernel irqchip with the kvm flic to get ais to work; else we'll fail with qemu-system-s390x: Failed to inject airq with AIS supported in the kernel_irqchip=off case, as we won't have an I/O adapter registered. Adding 'kvm_kernel_irqchip_required() &&' seems to do the trick; comments? > + kvm_vm_enable_cap(s, KVM_CAP_S390_AIS, 0); > + } > > kvm_set_max_memslot_size(KVM_SLOT_MAX_BYTES); > return 0;
