Re: [Qemu-devel] [PATCH v4 1/1] virtio-scsi-ccw: use ioeventfd even when KVM is disabled

[QingFeng Hao <haoqf@linux.vnet.ibm.com>]

在 2017/7/4 22:04, Christian Borntraeger 写道:
> On 07/04/2017 03:23 PM, QingFeng Hao wrote:
>> This patch is based on a similar patch from Stefan Hajnoczi -
>> commit c324fd0a39c ("virtio-pci: use ioeventfd even when KVM is disabled")
>>
>> 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.
>> Currently we don't have an equivalent to "memory: emulate ioeventfd"
>> for ccw yet, but that this doesn't hurt and qemu-iotests 068 can pass with
>> skipping iothread arguments.
>>
>> 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 <haoqf@linux.vnet.ibm.com>
>> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> I will take it via the s390-next tree.
>
> thanks applied.
Ok, thanks.
>> ---
>>   hw/s390x/virtio-ccw.c | 2 +-
>>   target/s390x/cpu.h    | 6 +++++-
>>   2 files changed, 6 insertions(+), 2 deletions(-)
>>
>> 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/cpu.h b/target/s390x/cpu.h
>> index 9faca04b52..bdb9bdbc9d 100644
>> --- a/target/s390x/cpu.h
>> +++ b/target/s390x/cpu.h
>> @@ -1264,7 +1264,11 @@ static inline int s390_assign_subch_ioeventfd(EventNotifier *notifier,
>>                                                 uint32_t sch_id, int vq,
>>                                                 bool assign)
>>   {
>> -    return kvm_s390_assign_subch_ioeventfd(notifier, sch_id, vq, assign);
>> +    if (kvm_enabled()) {
>> +        return kvm_s390_assign_subch_ioeventfd(notifier, sch_id, vq, assign);
>> +    } else {
>> +        return 0;
>> +    }
>>   }
>>
>>   static inline void s390_crypto_reset(void)
>>

-- 
Regards
QingFeng Hao