On 22.01.20 11:14, Thomas Huth 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 now for the machines that support proper CPU models.
>
> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1756946
> Signed-off-by: Thomas Huth <[email protected]>
> ---
> v5: Use cpu_model_allowed() as suggested by David. Seems to work as far
> as I can test it without PCI cards, but ping-pong migration with
> "-cpu host" from/to an older version of QEMU is now not working
> anymore - but I think that's kind of expected since "-cpu host"
> is not migration-safe anyway.
Yes, exactly.
>
> target/s390x/kvm.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> index 15260aeb9a..30112e529c 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 (cpu_model_allowed() && kvm_kernel_irqchip_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;
>
Reviewed-by: David Hildenbrand <[email protected]>
--
Thanks,
David / dhildenb
