Re: [PATCH] target/s390x/kvm: Enable adapter interruption suppression again

[Thomas Huth]

On 16/01/2020 13.50, Cornelia Huck wrote:
> On Thu, 16 Jan 2020 13:20:26 +0100
> Thomas Huth <address@hidden> 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.
>>
>> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1756946
>> Signed-off-by: Thomas Huth <address@hidden>
>> ---
>>  hw/s390x/s390-virtio-ccw.c         |  4 ++++
>>  include/hw/s390x/s390-virtio-ccw.h |  4 ++++
>>  target/s390x/kvm.c                 | 11 ++++++++---
>>  3 files changed, 16 insertions(+), 3 deletions(-)
>>
> 
>> @@ -365,10 +367,13 @@ 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 enable this for newer
> 
> s/necessary we only enable this/necessary, we only try to enable this/
> 
>> +     * machine types and if KVM_CAP_S390_AIS_MIGRATION is available.
> 
> maybe s/and if/if/

Sure ... could you fix it up when picking up the patch (in case I don't
have to respin), or do you want me to send a v2?

>>       */
>> -    /* kvm_vm_enable_cap(s, KVM_CAP_S390_AIS, 0); */
>> +    if (smc->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;
> 
> Looks good.
> 
> Remind me again: ais only made a difference for pci devices, right? Is
> it enough to give this a quick whirl with virtio-pci devices?

I don't remember the details, Christian, could you please answer this
question?

 Thomas