Jason Wang
2020-Jul-20 04:12 UTC
[PATCH vhost next 10/10] vdpa/mlx5: Add VDPA driver for supported mlx5 devices
On 2020/7/19 ??3:49, Eli Cohen wrote:> On Fri, Jul 17, 2020 at 04:57:29PM +0800, Jason Wang wrote: >>> Looks like checking intialized is enough. Will fix this. >>>>> + >>>>> +static void mlx5_vdpa_set_vq_ready(struct vdpa_device *vdev, u16 idx, bool ready) >>>>> +{ >>>>> + struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev); >>>>> + struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev); >>>>> + struct mlx5_vdpa_virtqueue *mvq = &ndev->vqs[idx]; >>>>> + int err; >>>>> + >>>>> + if (!mvq->ready && ready && mvq->fw_state != MLX5_VIRTIO_NET_Q_OBJECT_STATE_RDY) { >>>>> + err = modify_virtqueue(ndev, mvq, MLX5_VIRTIO_NET_Q_OBJECT_STATE_RDY); >>>>> + if (err) { >>>>> + mlx5_vdpa_warn(mvdev, "failed to modify virtqueue(%d)\n", err); >>>>> + return; >>>>> + } >>>>> + } >>>> I wonder what's the reason of changing vq state on the hardware >>>> here. I think we can defer it to set_status(). >>>> >>> I can defer this to set status. >>> >>> I just wonder if it is possible that the core vdpa driver may call this >>> function with ready equals false and after some time call it with ready >>> equals true. >> >> Good point, so I think we can keep the logic. But looks like the >> code can not work if ready equals false since it only tries to >> modify vq state to RDY. >> > The point is that you cannot modify the virtqueue to "not ready".Is this a hardware limitation of software one? I'm asking since we need support live migration. But a questions is how to stop the device but not reset, since we need get e.g last_avail_idx from the device. It could be either: 1) set_status(0) 2) get_vq_state() or 1) set_queue_ready(0) 2) get_vq_state() Set_status(0) means reset the virtio device but last_avail_idx is something out of virtio spec. I guess using set_queue_ready() is better. What's you opinion? Thanks> The > only option is to destroy it and create a new one. This means that if I > get ready equals false after the virtqueue has been created I need to > teardown the driver and set it up again. > > Given that, I think your original suggestion to defer this logic is > reasonable. >