Re: [PATCH v5] vdpa/mlx5: Avoid losing link state updates

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Apr 17, 2023 at 02:03:43PM +0300, Eli Cohen wrote:
> Current code ignores link state updates if VIRTIO_NET_F_STATUS was not
> negotiated. However, link state updates could be received before feature
> negotiation was completed , therefore causing link state events to be
> lost, possibly leaving the link state down.
> 
> Modify the code so link state notifier is registered after DRIVER_OK was
> negotiated and carry the registration only if
> VIRTIO_NET_F_STATUS was negotiated.  Unregister the notifier when the
> device is reset.
> 
> Fixes: 033779a708f0 ("vdpa/mlx5: make MTU/STATUS presence conditional on feature bits")
> Acked-by: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Eli Cohen <elic@nvidia.com>
> Message-Id: <20230404073347.40847-1-elic@nvidia.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

this should not be there either.

> ---
>  drivers/vdpa/mlx5/net/mlx5_vnet.c | 203 +++++++++++++++++-------------
>  1 file changed, 114 insertions(+), 89 deletions(-)
> v4 -> v5:
> Rebase over latest linux tree.
> 
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 195963b82b63..97a16f7eb894 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -2298,6 +2298,113 @@ static void update_cvq_info(struct mlx5_vdpa_dev *mvdev)
>  	}
>  }
>  
> +static u8 query_vport_state(struct mlx5_core_dev *mdev, u8 opmod, u16 vport)
> +{
> +	u32 out[MLX5_ST_SZ_DW(query_vport_state_out)] = {};
> +	u32 in[MLX5_ST_SZ_DW(query_vport_state_in)] = {};
> +	int err;
> +
> +	MLX5_SET(query_vport_state_in, in, opcode, MLX5_CMD_OP_QUERY_VPORT_STATE);
> +	MLX5_SET(query_vport_state_in, in, op_mod, opmod);
> +	MLX5_SET(query_vport_state_in, in, vport_number, vport);
> +	if (vport)
> +		MLX5_SET(query_vport_state_in, in, other_vport, 1);
> +
> +	err = mlx5_cmd_exec_inout(mdev, query_vport_state, in, out);
> +	if (err)
> +		return 0;
> +
> +	return MLX5_GET(query_vport_state_out, out, state);
> +}
> +
> +static bool get_link_state(struct mlx5_vdpa_dev *mvdev)
> +{
> +	if (query_vport_state(mvdev->mdev, MLX5_VPORT_STATE_OP_MOD_VNIC_VPORT, 0) ==
> +	    VPORT_STATE_UP)
> +		return true;
> +
> +	return false;
> +}
> +
> +static void update_carrier(struct work_struct *work)
> +{
> +	struct mlx5_vdpa_wq_ent *wqent;
> +	struct mlx5_vdpa_dev *mvdev;
> +	struct mlx5_vdpa_net *ndev;
> +
> +	wqent = container_of(work, struct mlx5_vdpa_wq_ent, work);
> +	mvdev = wqent->mvdev;
> +	ndev = to_mlx5_vdpa_ndev(mvdev);
> +	if (get_link_state(mvdev))
> +		ndev->config.status |= cpu_to_mlx5vdpa16(mvdev, VIRTIO_NET_S_LINK_UP);
> +	else
> +		ndev->config.status &= cpu_to_mlx5vdpa16(mvdev, ~VIRTIO_NET_S_LINK_UP);
> +
> +	if (ndev->config_cb.callback)
> +		ndev->config_cb.callback(ndev->config_cb.private);
> +
> +	kfree(wqent);
> +}
> +
> +static int queue_link_work(struct mlx5_vdpa_net *ndev)
> +{
> +	struct mlx5_vdpa_wq_ent *wqent;
> +
> +	wqent = kzalloc(sizeof(*wqent), GFP_ATOMIC);
> +	if (!wqent)
> +		return -ENOMEM;
> +
> +	wqent->mvdev = &ndev->mvdev;
> +	INIT_WORK(&wqent->work, update_carrier);
> +	queue_work(ndev->mvdev.wq, &wqent->work);
> +	return 0;
> +}
> +
> +static int event_handler(struct notifier_block *nb, unsigned long event, void *param)
> +{
> +	struct mlx5_vdpa_net *ndev = container_of(nb, struct mlx5_vdpa_net, nb);
> +	struct mlx5_eqe *eqe = param;
> +	int ret = NOTIFY_DONE;
> +
> +	if (event == MLX5_EVENT_TYPE_PORT_CHANGE) {
> +		switch (eqe->sub_type) {
> +		case MLX5_PORT_CHANGE_SUBTYPE_DOWN:
> +		case MLX5_PORT_CHANGE_SUBTYPE_ACTIVE:
> +			if (queue_link_work(ndev))
> +				return NOTIFY_DONE;
> +
> +			ret = NOTIFY_OK;
> +			break;
> +		default:
> +			return NOTIFY_DONE;
> +		}
> +		return ret;
> +	}
> +	return ret;
> +}
> +
> +static void register_link_notifier(struct mlx5_vdpa_net *ndev)
> +{
> +	if (!(ndev->mvdev.actual_features & BIT_ULL(VIRTIO_NET_F_STATUS)))
> +		return;
> +
> +	ndev->nb.notifier_call = event_handler;
> +	mlx5_notifier_register(ndev->mvdev.mdev, &ndev->nb);
> +	ndev->nb_registered = true;
> +	queue_link_work(ndev);
> +}
> +
> +static void unregister_link_notifier(struct mlx5_vdpa_net *ndev)
> +{
> +	if (!ndev->nb_registered)
> +		return;
> +
> +	ndev->nb_registered = false;
> +	mlx5_notifier_unregister(ndev->mvdev.mdev, &ndev->nb);
> +	if (ndev->mvdev.wq)
> +		flush_workqueue(ndev->mvdev.wq);
> +}
> +
>  static int mlx5_vdpa_set_driver_features(struct vdpa_device *vdev, u64 features)
>  {
>  	struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
> @@ -2567,10 +2674,11 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
>  				mlx5_vdpa_warn(mvdev, "failed to setup control VQ vring\n");
>  				goto err_setup;
>  			}
> +			register_link_notifier(ndev);
>  			err = setup_driver(mvdev);
>  			if (err) {
>  				mlx5_vdpa_warn(mvdev, "failed to setup driver\n");
> -				goto err_setup;
> +				goto err_driver;
>  			}
>  		} else {
>  			mlx5_vdpa_warn(mvdev, "did not expect DRIVER_OK to be cleared\n");
> @@ -2582,6 +2690,8 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
>  	up_write(&ndev->reslock);
>  	return;
>  
> +err_driver:
> +	unregister_link_notifier(ndev);
>  err_setup:
>  	mlx5_vdpa_destroy_mr(&ndev->mvdev);
>  	ndev->mvdev.status |= VIRTIO_CONFIG_S_FAILED;
> @@ -2607,6 +2717,7 @@ static int mlx5_vdpa_reset(struct vdpa_device *vdev)
>  	mlx5_vdpa_info(mvdev, "performing device reset\n");
>  
>  	down_write(&ndev->reslock);
> +	unregister_link_notifier(ndev);
>  	teardown_driver(ndev);
>  	clear_vqs_ready(ndev);
>  	mlx5_vdpa_destroy_mr(&ndev->mvdev);
> @@ -2861,9 +2972,7 @@ static int mlx5_vdpa_suspend(struct vdpa_device *vdev)
>  	mlx5_vdpa_info(mvdev, "suspending device\n");
>  
>  	down_write(&ndev->reslock);
> -	ndev->nb_registered = false;
> -	mlx5_notifier_unregister(mvdev->mdev, &ndev->nb);
> -	flush_workqueue(ndev->mvdev.wq);
> +	unregister_link_notifier(ndev);
>  	for (i = 0; i < ndev->cur_num_vqs; i++) {
>  		mvq = &ndev->vqs[i];
>  		suspend_vq(ndev, mvq);
> @@ -3000,84 +3109,6 @@ struct mlx5_vdpa_mgmtdev {
>  	struct mlx5_vdpa_net *ndev;
>  };
>  
> -static u8 query_vport_state(struct mlx5_core_dev *mdev, u8 opmod, u16 vport)
> -{
> -	u32 out[MLX5_ST_SZ_DW(query_vport_state_out)] = {};
> -	u32 in[MLX5_ST_SZ_DW(query_vport_state_in)] = {};
> -	int err;
> -
> -	MLX5_SET(query_vport_state_in, in, opcode, MLX5_CMD_OP_QUERY_VPORT_STATE);
> -	MLX5_SET(query_vport_state_in, in, op_mod, opmod);
> -	MLX5_SET(query_vport_state_in, in, vport_number, vport);
> -	if (vport)
> -		MLX5_SET(query_vport_state_in, in, other_vport, 1);
> -
> -	err = mlx5_cmd_exec_inout(mdev, query_vport_state, in, out);
> -	if (err)
> -		return 0;
> -
> -	return MLX5_GET(query_vport_state_out, out, state);
> -}
> -
> -static bool get_link_state(struct mlx5_vdpa_dev *mvdev)
> -{
> -	if (query_vport_state(mvdev->mdev, MLX5_VPORT_STATE_OP_MOD_VNIC_VPORT, 0) ==
> -	    VPORT_STATE_UP)
> -		return true;
> -
> -	return false;
> -}
> -
> -static void update_carrier(struct work_struct *work)
> -{
> -	struct mlx5_vdpa_wq_ent *wqent;
> -	struct mlx5_vdpa_dev *mvdev;
> -	struct mlx5_vdpa_net *ndev;
> -
> -	wqent = container_of(work, struct mlx5_vdpa_wq_ent, work);
> -	mvdev = wqent->mvdev;
> -	ndev = to_mlx5_vdpa_ndev(mvdev);
> -	if (get_link_state(mvdev))
> -		ndev->config.status |= cpu_to_mlx5vdpa16(mvdev, VIRTIO_NET_S_LINK_UP);
> -	else
> -		ndev->config.status &= cpu_to_mlx5vdpa16(mvdev, ~VIRTIO_NET_S_LINK_UP);
> -
> -	if (ndev->nb_registered && ndev->config_cb.callback)
> -		ndev->config_cb.callback(ndev->config_cb.private);
> -
> -	kfree(wqent);
> -}
> -
> -static int event_handler(struct notifier_block *nb, unsigned long event, void *param)
> -{
> -	struct mlx5_vdpa_net *ndev = container_of(nb, struct mlx5_vdpa_net, nb);
> -	struct mlx5_eqe *eqe = param;
> -	int ret = NOTIFY_DONE;
> -	struct mlx5_vdpa_wq_ent *wqent;
> -
> -	if (event == MLX5_EVENT_TYPE_PORT_CHANGE) {
> -		if (!(ndev->mvdev.actual_features & BIT_ULL(VIRTIO_NET_F_STATUS)))
> -			return NOTIFY_DONE;
> -		switch (eqe->sub_type) {
> -		case MLX5_PORT_CHANGE_SUBTYPE_DOWN:
> -		case MLX5_PORT_CHANGE_SUBTYPE_ACTIVE:
> -			wqent = kzalloc(sizeof(*wqent), GFP_ATOMIC);
> -			if (!wqent)
> -				return NOTIFY_DONE;
> -
> -			wqent->mvdev = &ndev->mvdev;
> -			INIT_WORK(&wqent->work, update_carrier);
> -			queue_work(ndev->mvdev.wq, &wqent->work);
> -			ret = NOTIFY_OK;
> -			break;
> -		default:
> -			return NOTIFY_DONE;
> -		}
> -		return ret;
> -	}
> -	return ret;
> -}
> -
>  static int config_func_mtu(struct mlx5_core_dev *mdev, u16 mtu)
>  {
>  	int inlen = MLX5_ST_SZ_BYTES(modify_nic_vport_context_in);
> @@ -3258,9 +3289,6 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
>  		goto err_res2;
>  	}
>  
> -	ndev->nb.notifier_call = event_handler;
> -	mlx5_notifier_register(mdev, &ndev->nb);
> -	ndev->nb_registered = true;
>  	mvdev->vdev.mdev = &mgtdev->mgtdev;
>  	err = _vdpa_register_device(&mvdev->vdev, max_vqs + 1);
>  	if (err)
> @@ -3294,10 +3322,7 @@ static void mlx5_vdpa_dev_del(struct vdpa_mgmt_dev *v_mdev, struct vdpa_device *
>  
>  	mlx5_vdpa_remove_debugfs(ndev->debugfs);
>  	ndev->debugfs = NULL;
> -	if (ndev->nb_registered) {
> -		ndev->nb_registered = false;
> -		mlx5_notifier_unregister(mvdev->mdev, &ndev->nb);
> -	}
> +	unregister_link_notifier(ndev);
>  	wq = mvdev->wq;
>  	mvdev->wq = NULL;
>  	destroy_workqueue(wq);
> -- 
> 2.39.2

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