From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Thomas Huth <thuth@redhat.com>, Cornelia Huck <cohuck@redhat.com>,
Matthew Rosato <mjrosato@linux.ibm.com>
Cc: Halil Pasic <pasic@linux.ibm.com>,
qemu-s390x@nongnu.org, qemu-devel@nongnu.org,
David Hildenbrand <david@redhat.com>
Subject: Re: [PATCH] target/s390x/kvm: Enable adapter interruption suppression again
Date: Fri, 17 Jan 2020 12:05:30 +0100 [thread overview]
Message-ID: <a1cda187-adfc-bc9d-8b66-5fd48c7e2856@de.ibm.com> (raw)
In-Reply-To: <d59cf080-bb0c-91af-08fc-1cfd7a32663e@redhat.com>
On 17.01.20 11:38, Thomas Huth wrote:
> On 16/01/2020 21.26, Cornelia Huck wrote:
>> On Thu, 16 Jan 2020 15:19:13 -0500
>> Matthew Rosato <mjrosato@linux.ibm.com> wrote:
>>
>>> On 1/16/20 7:20 AM, 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 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 <thuth@redhat.com>
>>>> ---
>>>> 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(-)
>>
>> (...)
>>
>>>> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
>>>> index 15260aeb9a..4c1c8c0208 100644
>>>> --- a/target/s390x/kvm.c
>>>> +++ b/target/s390x/kvm.c
>>>> @@ -329,6 +329,8 @@ static void ccw_machine_class_foreach(ObjectClass *oc, void *opaque)
>>>>
>>>> int kvm_arch_init(MachineState *ms, KVMState *s)
>>>> {
>>>> + S390CcwMachineClass *smc = S390_CCW_MACHINE_OBJ_GET_CLASS(ms);
>>>> +
>>>
>>> I still can't run a proper test due to unavailable hw but in the
>>> meantime I tried to virsh define a libvirt guest pointed at qemu (master
>>> + this patch). Regardless of machine type (s390-ccw-virtio-5.0 or
>>> s390-ccw-virtio-4.2) I get:
>>>
>>> virsh define guest.xml
>>> error: Failed to define domain from /path/to/guest.xml
>>> error: invalid argument: could not find capabilities for arch=s390x
>>> domaintype=kvm
>>>
>>> Similarly:
>>>
>>> virsh domcapabilities
>>> error: failed to get emulator capabilities
>>> error: invalid argument: unable to find any emulator to serve 's390x'
>>> architecture
>>>
>>> Rolling back to qemu master, the define and domcapabilities work (with
>>> no ais of course).
>>>
>>> So: there is some incompatibility between the way libvirt invokes qemu
>>> to detect capabilities and this code. The above line seems to be the
>>> root problem - if I take your patch and remove 'smc' then libvirt works
>>> as expected and I can see ais in the domcapabilities.
>>>
>>> Looking at those wrappers David mentioned... I suspect you need this
>>> for the 'none' machine case. I tried a quick hack with the following:
>>>
>>> bool ais_allowed(void)
>>> {
>>> /* for "none" machine this results in true */
>>> return get_machine_class()->kvm_ais_allowed;
>>> }
>>>
>>> and
>>>
>>> if (ais_allowed() &&
>>> kvm_check_extension(s, KVM_CAP_S390_AIS_MIGRATION)) {
>>> kvm_vm_enable_cap(s, KVM_CAP_S390_AIS, 0);
>>> }
>>>
>>> This works and doesn't break libvirt compatibility detection.
>>
>> Oh, "none" machine fun again... I think you're on the right track, and
>> we really need a wrapper.
>
> D'oh, so this is the real reason for the wrappers ... ok, I'll respin my
> patch accordingly.
Can you add a comment to the wrappers?
>
> Thanks a lot for the testing, Matthew!
>
> Thomas
>
next prev parent reply other threads:[~2020-01-17 11:06 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-16 12:20 [PATCH] target/s390x/kvm: Enable adapter interruption suppression again Thomas Huth
2020-01-16 12:23 ` David Hildenbrand
2020-01-16 12:26 ` Thomas Huth
2020-01-16 12:28 ` David Hildenbrand
2020-01-16 12:38 ` Thomas Huth
2020-01-16 12:50 ` Cornelia Huck
2020-01-16 12:55 ` Thomas Huth
2020-01-16 13:22 ` Christian Borntraeger
2020-01-16 14:22 ` Cornelia Huck
2020-01-16 14:51 ` Matthew Rosato
2020-01-16 20:19 ` Matthew Rosato
2020-01-16 20:26 ` Cornelia Huck
2020-01-17 10:38 ` Thomas Huth
2020-01-17 11:05 ` Christian Borntraeger [this message]
2020-01-17 15:38 ` Thomas Huth
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