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

[Christian Borntraeger]

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 <address@hidden>
> Reviewed-by: Cornelia Huck <address@hidden>

I will take it via the s390-next tree.

thanks applied.

> ---
>  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)
>