Re: [PATCH v2 16/21] net/virtio-user: allocate shadow control queue

[Maxime Coquelin]

On 2/7/23 19:06, Eugenio Perez Martin wrote:

On Tue, Feb 7, 2023 at 4:18 PM Maxime Coquelin
<maxime.coque...@redhat.com> wrote:

If the backends supports control virtqueue, allocate a
shadow control virtqueue, and implement the notify callback
that writes into the kickfd.

Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com>
Reviewed-by: Chenbo Xia <chenbo....@intel.com>

Even with the nitpick below,

Acked-by: Eugenio Pérez <epere...@redhat.com>

---
  .../net/virtio/virtio_user/virtio_user_dev.c  | 47 ++++++++++++++++++-
  .../net/virtio/virtio_user/virtio_user_dev.h  |  5 ++
  drivers/net/virtio/virtio_user_ethdev.c       |  6 +++
  3 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c 
b/drivers/net/virtio/virtio_user/virtio_user_dev.c
index a3584e7735..16a0e07413 100644
--- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
+++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
@@ -146,8 +146,9 @@ virtio_user_dev_set_features(struct virtio_user_dev *dev)

         /* Strip VIRTIO_NET_F_MAC, as MAC address is handled in vdev init */
         features &= ~(1ull << VIRTIO_NET_F_MAC);
-       /* Strip VIRTIO_NET_F_CTRL_VQ, as devices do not really need to know */
-       features &= ~(1ull << VIRTIO_NET_F_CTRL_VQ);
+       /* Strip VIRTIO_NET_F_CTRL_VQ if the devices does not really support 
control VQ */
+       if (!dev->hw_cvq)
+               features &= ~(1ull << VIRTIO_NET_F_CTRL_VQ);
         features &= ~(1ull << VIRTIO_NET_F_STATUS);
         ret = dev->ops->set_features(dev, features);
         if (ret < 0)
@@ -911,6 +912,48 @@ virtio_user_handle_cq(struct virtio_user_dev *dev, 
uint16_t queue_idx)
         }
  }

+static void
+virtio_user_control_queue_notify(struct virtqueue *vq, void *cookie)
+{
+       struct virtio_user_dev *dev = cookie;
+       uint64_t buf = 1;
+
+       if (write(dev->kickfds[vq->vq_queue_index], &buf, sizeof(buf)) < 0)
+               PMD_DRV_LOG(ERR, "failed to kick backend: %s",
+                           strerror(errno));
+}
+
+int
+virtio_user_dev_create_shadow_cvq(struct virtio_user_dev *dev, struct 
virtqueue *vq)
+{
+       char name[VIRTQUEUE_MAX_NAME_SZ];
+       struct virtqueue *scvq;
+
+       snprintf(name, sizeof(name), "port%d_shadow_cvq", vq->hw->port_id);
+       scvq = virtqueue_alloc(&dev->hw, vq->vq_queue_index, vq->vq_nentries,
+                       VTNET_CQ, SOCKET_ID_ANY, name);
+       if (!scvq) {
+               PMD_INIT_LOG(ERR, "(%s) Failed to alloc shadow control vq\n", 
dev->path);
+               return -ENOMEM;
+       }
+
+       scvq->cq.notify_queue = &virtio_user_control_queue_notify;
+       scvq->cq.notify_cookie = dev;
+       dev->scvq = scvq;
+
+       return 0;
+}
+
+void
+virtio_user_dev_destroy_shadow_cvq(struct virtio_user_dev *dev)
+{
+       if (!dev->scvq)
+               return;
+
+       virtqueue_free(dev->scvq);
+       dev->scvq = NULL;
+}
+
  int
  virtio_user_dev_set_status(struct virtio_user_dev *dev, uint8_t status)
  {
diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.h 
b/drivers/net/virtio/virtio_user/virtio_user_dev.h
index 3c5453eac0..e0db4faf3f 100644
--- a/drivers/net/virtio/virtio_user/virtio_user_dev.h
+++ b/drivers/net/virtio/virtio_user/virtio_user_dev.h
@@ -58,6 +58,9 @@ struct virtio_user_dev {
         pthread_mutex_t mutex;
         bool            started;

+       bool                    hw_cvq;
+       struct virtqueue        *scvq;
+
         void *backend_data;
  };

@@ -74,6 +77,8 @@ void virtio_user_handle_cq(struct virtio_user_dev *dev, 
uint16_t queue_idx);
  void virtio_user_handle_cq_packed(struct virtio_user_dev *dev,
                                   uint16_t queue_idx);
  uint8_t virtio_user_handle_mq(struct virtio_user_dev *dev, uint16_t q_pairs);
+int virtio_user_dev_create_shadow_cvq(struct virtio_user_dev *dev, struct 
virtqueue *vq);
+void virtio_user_dev_destroy_shadow_cvq(struct virtio_user_dev *dev);
  int virtio_user_dev_set_status(struct virtio_user_dev *dev, uint8_t status);
  int virtio_user_dev_update_status(struct virtio_user_dev *dev);
  int virtio_user_dev_update_link_state(struct virtio_user_dev *dev);
diff --git a/drivers/net/virtio/virtio_user_ethdev.c 
b/drivers/net/virtio/virtio_user_ethdev.c
index 6c3e875793..626bd95b62 100644
--- a/drivers/net/virtio/virtio_user_ethdev.c
+++ b/drivers/net/virtio/virtio_user_ethdev.c
@@ -232,6 +232,9 @@ virtio_user_setup_queue(struct virtio_hw *hw, struct 
virtqueue *vq)
         else
                 virtio_user_setup_queue_split(vq, dev);

+       if (dev->hw_cvq && hw->cvq && (virtnet_cq_to_vq(hw->cvq) == vq))
+               return virtio_user_dev_create_shadow_cvq(dev, vq);
+
         return 0;
  }

@@ -251,6 +254,9 @@ virtio_user_del_queue(struct virtio_hw *hw, struct 
virtqueue *vq)

         close(dev->callfds[vq->vq_queue_index]);
         close(dev->kickfds[vq->vq_queue_index]);
+
+       if (hw->cvq && (virtnet_cq_to_vq(hw->cvq) == vq) && dev->scvq)

Not sure if intended, but check for dev->scvq is already in
virtio_user_dev_destroy_shadow_cvq.

This was not intended, I can remove it in next revision.

Thanks,
Maxime

+               virtio_user_dev_destroy_shadow_cvq(dev);
  }

  static void
--
2.39.1