On Tue, 21 Jan 2020 09:33:02 -0500 Matthew Rosato <mjros...@linux.ibm.com> wrote:
> On 1/20/20 12:27 PM, Cornelia Huck wrote: > > 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? > > > > In spirit, I agree with this idea. But, a quick test shows that putting > this check here results in ais=off for the 'none' machine case (libvirt > capabilities detection). I think we have to only look at > kvm_kernel_irqchip_required() when working with a real machine. Sigh, I think you're right again. We need to check for the 'none' machine here; but I can't think of a non-ugly way to do so... > > >> + kvm_vm_enable_cap(s, KVM_CAP_S390_AIS, 0); > >> + } > >> > >> kvm_set_max_memslot_size(KVM_SLOT_MAX_BYTES); > >> return 0; > > > > >
