Re: [RFC 1/2] virtio-net: disable the configure interrupt for not support device

[Jason Wang]

On Wed, Mar 27, 2024 at 9:29 AM Cindy Lu <lulu@redhat.com> wrote:
>
> Only the vdpa device support configure interrupt, we need to disable the
> configure interrupt process in all other device.

I think we need to tweak the terminology here at least.

It's not about configure interrupt, it's about whether or not we can
try to use irqfd for configure interrupt.

Btw, have you tried this on the old kernel that doesn't support
configure interrupt for vDPA?

> In order to achieve this, I added a check in the virtio_net_device_realize().
> When the peer's type is vdpa, the value of config_irq_enabled in the structure
> VirtIODevice will set to true.
>
> Signed-off-by: Cindy Lu <lulu@redhat.com>
> ---
>  hw/net/virtio-net.c        | 5 ++++-
>  hw/virtio/virtio.c         | 1 +
>  include/hw/virtio/virtio.h | 1 +
>  3 files changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 80c56f0cfc..3b487864a8 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -3749,12 +3749,15 @@ static void virtio_net_device_realize(DeviceState 
> *dev, Error **errp)
>
>      nc = qemu_get_queue(n->nic);
>      nc->rxfilter_notify_enabled = 1;
> +    vdev->config_irq_enabled = false;

Let's tweak the name of the variable.

But in another thought, there's no easy way to know if vDPA support
configure interrupt at device realization.

We need a graceful fallback or just disable irqfd to configure irq.

>
> -   if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) {
> +    if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) {
>          struct virtio_net_config netcfg = {};
>          memcpy(&netcfg.mac, &n->nic_conf.macaddr, ETH_ALEN);
>          vhost_net_set_config(get_vhost_net(nc->peer),
>              (uint8_t *)&netcfg, 0, ETH_ALEN, VHOST_SET_CONFIG_TYPE_FRONTEND);
> +
> +        vdev->config_irq_enabled = true;
>      }
>      QTAILQ_INIT(&n->rsc_chains);
>      n->qdev = dev;
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 3a160f86ed..6b52a7190d 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -3255,6 +3255,7 @@ void virtio_init(VirtIODevice *vdev, uint16_t 
> device_id, size_t config_size)
>              virtio_vmstate_change, vdev);
>      vdev->device_endian = virtio_default_endian();
>      vdev->use_guest_notifier_mask = true;
> +    vdev->config_irq_enabled = false;
>  }
>
>  /*
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index c8f72850bc..a7763b71e0 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -164,6 +164,7 @@ struct VirtIODevice
>       */
>      EventNotifier config_notifier;
>      bool device_iotlb_enabled;
> +    bool config_irq_enabled;
>  };
>
>  struct VirtioDeviceClass {

Thanks

> --
> 2.43.0
>