[PATCH v2 15/21] net/virtio-user: get max number of queue pairs from device

[Eugenio Perez Martin]

On Tue, Feb 7, 2023 at 4:18 PM Maxime Coquelin
<maxime.coquelin at redhat.com> wrote:
>
> When supported by the backend (only vDPA for now), this
> patch gets the maximum number of queue pairs supported by
> the device by querying it in its config space.
>
> This is required for adding backend control queue support,
> as is index equals the maximum number of queues supported
> by the device as described by the Virtio specification.
>
> Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
> Reviewed-by: Chenbo Xia <chenbo.xia at intel.com>

Acked-by: Eugenio Pérez <eperezma at redhat.com>

> ---
>  .../net/virtio/virtio_user/virtio_user_dev.c  | 93 ++++++++++++++-----
>  drivers/net/virtio/virtio_user_ethdev.c       |  7 --
>  2 files changed, 71 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c b/drivers/net/virtio/virtio_user/virtio_user_dev.c
> index 809c9ef442..a3584e7735 100644
> --- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
> +++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
> @@ -253,6 +253,50 @@ int virtio_user_stop_device(struct virtio_user_dev *dev)
>         return -1;
>  }
>
> +static int
> +virtio_user_dev_init_max_queue_pairs(struct virtio_user_dev *dev, uint32_t user_max_qp)
> +{
> +       int ret;
> +
> +       if (!(dev->device_features & (1ULL << VIRTIO_NET_F_MQ))) {
> +               dev->max_queue_pairs = 1;
> +               return 0;
> +       }
> +
> +       if (!dev->ops->get_config) {
> +               dev->max_queue_pairs = user_max_qp;
> +               return 0;
> +       }
> +
> +       ret = dev->ops->get_config(dev, (uint8_t *)&dev->max_queue_pairs,
> +                       offsetof(struct virtio_net_config, max_virtqueue_pairs),
> +                       sizeof(uint16_t));
> +       if (ret) {
> +               /*
> +                * We need to know the max queue pair from the device so that
> +                * the control queue gets the right index.
> +                */
> +               dev->max_queue_pairs = 1;
> +               PMD_DRV_LOG(ERR, "(%s) Failed to get max queue pairs from device", dev->path);
> +
> +               return ret;
> +       }
> +
> +       if (dev->max_queue_pairs > VIRTIO_MAX_VIRTQUEUE_PAIRS) {
> +               /*
> +                * If the device supports control queue, the control queue
> +                * index is max_virtqueue_pairs * 2. Disable MQ if it happens.
> +                */
> +               PMD_DRV_LOG(ERR, "(%s) Device advertises too many queues (%u, max supported %u)",
> +                               dev->path, dev->max_queue_pairs, VIRTIO_MAX_VIRTQUEUE_PAIRS);
> +               dev->max_queue_pairs = 1;
> +
> +               return -1;
> +       }
> +
> +       return 0;
> +}
> +
>  int
>  virtio_user_dev_set_mac(struct virtio_user_dev *dev)
>  {
> @@ -511,24 +555,7 @@ virtio_user_dev_setup(struct virtio_user_dev *dev)
>                 return -1;
>         }
>
> -       if (virtio_user_dev_init_notify(dev) < 0) {
> -               PMD_INIT_LOG(ERR, "(%s) Failed to init notifiers", dev->path);
> -               goto destroy;
> -       }
> -
> -       if (virtio_user_fill_intr_handle(dev) < 0) {
> -               PMD_INIT_LOG(ERR, "(%s) Failed to init interrupt handler", dev->path);
> -               goto uninit;
> -       }
> -
>         return 0;
> -
> -uninit:
> -       virtio_user_dev_uninit_notify(dev);
> -destroy:
> -       dev->ops->destroy(dev);
> -
> -       return -1;
>  }
>
>  /* Use below macro to filter features from vhost backend */
> @@ -570,7 +597,6 @@ virtio_user_dev_init(struct virtio_user_dev *dev, char *path, uint16_t queues,
>         }
>
>         dev->started = 0;
> -       dev->max_queue_pairs = queues;
>         dev->queue_pairs = 1; /* mq disabled by default */
>         dev->queue_size = queue_size;
>         dev->is_server = server;
> @@ -591,23 +617,39 @@ virtio_user_dev_init(struct virtio_user_dev *dev, char *path, uint16_t queues,
>
>         if (dev->ops->set_owner(dev) < 0) {
>                 PMD_INIT_LOG(ERR, "(%s) Failed to set backend owner", dev->path);
> -               return -1;
> +               goto destroy;
>         }
>
>         if (dev->ops->get_backend_features(&backend_features) < 0) {
>                 PMD_INIT_LOG(ERR, "(%s) Failed to get backend features", dev->path);
> -               return -1;
> +               goto destroy;
>         }
>
>         dev->unsupported_features = ~(VIRTIO_USER_SUPPORTED_FEATURES | backend_features);
>
>         if (dev->ops->get_features(dev, &dev->device_features) < 0) {
>                 PMD_INIT_LOG(ERR, "(%s) Failed to get device features", dev->path);
> -               return -1;
> +               goto destroy;
>         }
>
>         virtio_user_dev_init_mac(dev, mac);
>
> +       if (virtio_user_dev_init_max_queue_pairs(dev, queues))
> +               dev->unsupported_features |= (1ull << VIRTIO_NET_F_MQ);
> +
> +       if (dev->max_queue_pairs > 1)
> +               cq = 1;
> +
> +       if (virtio_user_dev_init_notify(dev) < 0) {
> +               PMD_INIT_LOG(ERR, "(%s) Failed to init notifiers", dev->path);
> +               goto destroy;
> +       }
> +
> +       if (virtio_user_fill_intr_handle(dev) < 0) {
> +               PMD_INIT_LOG(ERR, "(%s) Failed to init interrupt handler", dev->path);
> +               goto notify_uninit;
> +       }
> +
>         if (!mrg_rxbuf)
>                 dev->unsupported_features |= (1ull << VIRTIO_NET_F_MRG_RXBUF);
>
> @@ -651,11 +693,18 @@ virtio_user_dev_init(struct virtio_user_dev *dev, char *path, uint16_t queues,
>                 if (rte_errno != ENOTSUP) {
>                         PMD_INIT_LOG(ERR, "(%s) Failed to register mem event callback",
>                                         dev->path);
> -                       return -1;
> +                       goto notify_uninit;
>                 }
>         }
>
>         return 0;
> +
> +notify_uninit:
> +       virtio_user_dev_uninit_notify(dev);
> +destroy:
> +       dev->ops->destroy(dev);
> +
> +       return -1;
>  }
>
>  void
> diff --git a/drivers/net/virtio/virtio_user_ethdev.c b/drivers/net/virtio/virtio_user_ethdev.c
> index 6ad5896378..6c3e875793 100644
> --- a/drivers/net/virtio/virtio_user_ethdev.c
> +++ b/drivers/net/virtio/virtio_user_ethdev.c
> @@ -595,8 +595,6 @@ virtio_user_pmd_probe(struct rte_vdev_device *vdev)
>                                      VIRTIO_USER_ARG_CQ_NUM);
>                         goto end;
>                 }
> -       } else if (queues > 1) {
> -               cq = 1;
>         }
>
>         if (rte_kvargs_count(kvlist, VIRTIO_USER_ARG_PACKED_VQ) == 1) {
> @@ -617,11 +615,6 @@ virtio_user_pmd_probe(struct rte_vdev_device *vdev)
>                 }
>         }
>
> -       if (queues > 1 && cq == 0) {
> -               PMD_INIT_LOG(ERR, "multi-q requires ctrl-q");
> -               goto end;
> -       }
> -
>         if (queues > VIRTIO_MAX_VIRTQUEUE_PAIRS) {
>                 PMD_INIT_LOG(ERR, "arg %s %" PRIu64 " exceeds the limit %u",
>                         VIRTIO_USER_ARG_QUEUES_NUM, queues,
> --
> 2.39.1
>