Re: [Qemu-block] [PATCH 1/1] virtio-scsi-ccw: use ioeventfd even when KVM is disabled

[Christian Borntraeger]

On 07/03/2017 10:08 AM, QingFeng Hao wrote:
> 
> 
> 在 2017/7/3 15:41, Christian Borntraeger 写道:
>> On 07/03/2017 09:38 AM, QingFeng Hao wrote:
>>> Do not check kvm_eventfds_enabled() when KVM is disabled since it
>>> always returns 0.  Since commit 8c56c1a592b5092d91da8d8943c17777d6462a6f
>>> ("memory: emulate ioeventfd") it has been possible to use ioeventfds in
>>> qtest or TCG mode.
>>>
>>> This patch makes -device virtio-scsi-ccw,iothread=iothread0 work even
>>> when KVM is disabled.
>>>
>>> I have tested that virtio-scsi-ccw works under tcg both with and without
>>> iothread.
>>>
>>> This patch fixes qemu-iotests 068, which was accidentally merged early
>>> despite the dependency on ioeventfd.
>>>
>>> Signed-off-by: QingFeng Hao <address@hidden>
>>> Signed-off-by: Stefan Hajnoczi <address@hidden>
>> cut'n'paste mistake of adding Stefans signoff?
>>
>> Otherwise it looks good.
> I just want to mark that this patch is related with the former one from 
> Stefan.
> Is that ok to add this sign-off? thanks!

No, sign-off indicates who passes the patch along for integration, so only 
Stefan
is allowed to add that - if he actually takes the patch. It is very important 
to 
not mangle the sign-off-chain as it is actually used to track how a patch moved 
from
the developer into the tree.

You can give credit to Stefan in the patch description - e.g. by saying in the 
patch
description something like 

based on a similar patch from Stefan Hajnoczi - commit c324fd0a39c (" 
virtio-pci: use 
ioeventfd even when KVM is disabled)



>>> ---
>>>   hw/s390x/virtio-ccw.c | 2 +-
>>>   target/s390x/kvm.c    | 3 +++
>>>   2 files changed, 4 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
>>> index 90d37cb9ff..35896eb007 100644
>>> --- a/hw/s390x/virtio-ccw.c
>>> +++ b/hw/s390x/virtio-ccw.c
>>> @@ -711,7 +711,7 @@ static void virtio_ccw_device_realize(VirtioCcwDevice 
>>> *dev, Error **errp)
>>>           sch->cssid, sch->ssid, sch->schid, sch->devno,
>>>           ccw_dev->devno.valid ? "user-configured" : "auto-configured");
>>>
>>> -    if (!kvm_eventfds_enabled()) {
>>> +    if (kvm_enabled() && !kvm_eventfds_enabled()) {
>>>           dev->flags &= ~VIRTIO_CCW_FLAG_USE_IOEVENTFD;
>>>       }
>>>
>>> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
>>> index a3d00196f4..c37f9c3b9e 100644
>>> --- a/target/s390x/kvm.c
>>> +++ b/target/s390x/kvm.c
>>> @@ -2220,6 +2220,9 @@ int kvm_s390_assign_subch_ioeventfd(EventNotifier 
>>> *notifier, uint32_t sch,
>>>           .addr = sch,
>>>           .len = 8,
>>>       };
>>> +    if (!kvm_enabled()) {
>>> +        return 0;
>>> +    }
>>>       if (!kvm_check_extension(kvm_state, KVM_CAP_IOEVENTFD)) {
>>>           return -ENOSYS;
>>>       }
>>>
>