Re: [PATCH 2/2] vdpa/mlx5: Support configuring max data virtqueues

[Si-Wei Liu <si-wei.liu@oracle.com>]

On 11/30/2021 1:48 AM, Eli Cohen wrote:
> Check if the required number of data virtqueues was provided when a
> adding a new device and verify the new value does not exceed device
> capabilities.
>
> In addition, change the arrays holding virtqueue and callback contexts
> to be dynamically allocated.
>
> Signed-off-by: Eli Cohen <elic@nvidia.com>
> ---
>   drivers/vdpa/mlx5/net/mlx5_vnet.c | 32 +++++++++++++++++++------------
>   1 file changed, 20 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 63813fbb5f62..54e276e0df18 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -131,11 +131,6 @@ struct mlx5_vdpa_virtqueue {
>   	struct mlx5_vq_restore_info ri;
>   };
>   
> -/* We will remove this limitation once mlx5_vdpa_alloc_resources()
> - * provides for driver space allocation
> - */
> -#define MLX5_MAX_SUPPORTED_VQS 16
> -
>   static bool is_index_valid(struct mlx5_vdpa_dev *mvdev, u16 idx)
>   {
>   	if (unlikely(idx > mvdev->max_idx))
> @@ -148,8 +143,8 @@ struct mlx5_vdpa_net {
>   	struct mlx5_vdpa_dev mvdev;
>   	struct mlx5_vdpa_net_resources res;
>   	struct virtio_net_config config;
> -	struct mlx5_vdpa_virtqueue vqs[MLX5_MAX_SUPPORTED_VQS];
> -	struct vdpa_callback event_cbs[MLX5_MAX_SUPPORTED_VQS + 1];
> +	struct mlx5_vdpa_virtqueue *vqs;
> +	struct vdpa_callback *event_cbs;
>   
>   	/* Serialize vq resources creation and destruction. This is required
>   	 * since memory map might change and we need to destroy and create
> @@ -1218,7 +1213,7 @@ static void suspend_vqs(struct mlx5_vdpa_net *ndev)
>   {
>   	int i;
>   
> -	for (i = 0; i < MLX5_MAX_SUPPORTED_VQS; i++)
> +	for (i = 0; i < ndev->mvdev.max_vqs; i++)
>   		suspend_vq(ndev, &ndev->vqs[i]);
>   }
>   
> @@ -1245,7 +1240,7 @@ static int create_rqt(struct mlx5_vdpa_net *ndev)
>   	int i, j;
>   	int err;
>   
> -	max_rqt = min_t(int, MLX5_MAX_SUPPORTED_VQS / 2,
> +	max_rqt = min_t(int, ndev->mvdev.max_vqs  / 2,
>   			1 << MLX5_CAP_GEN(ndev->mvdev.mdev, log_max_rqt_size));
Here the user configured number of data vqs may get silently capped to 
what the device can support (up to 2^log_max_rqt_size). Do you consider 
expose this device specific capacity to vdpa users so it doesn't get 
blindly misconfigured, and/or return appropriate error message to 
indicate the failure cause?

If mlx5 vdpa really can't support power of 2 number of data vqs due to 
hardware limitation (?), an appropriate message should be returned here.

-Siwei
>   	if (max_rqt < 1)
>   		return -EOPNOTSUPP;
> @@ -2235,7 +2230,7 @@ static int mlx5_vdpa_reset(struct vdpa_device *vdev)
>   	clear_vqs_ready(ndev);
>   	mlx5_vdpa_destroy_mr(&ndev->mvdev);
>   	ndev->mvdev.status = 0;
> -	memset(ndev->event_cbs, 0, sizeof(ndev->event_cbs));
> +	memset(ndev->event_cbs, 0, sizeof(*ndev->event_cbs) * (mvdev->max_vqs + 1));
>   	ndev->mvdev.actual_features = 0;
>   	++mvdev->generation;
>   	if (MLX5_CAP_GEN(mvdev->mdev, umem_uid_0)) {
> @@ -2308,6 +2303,8 @@ static void mlx5_vdpa_free(struct vdpa_device *vdev)
>   	}
>   	mlx5_vdpa_free_resources(&ndev->mvdev);
>   	mutex_destroy(&ndev->reslock);
> +	kfree(ndev->event_cbs);
> +	kfree(ndev->vqs);
>   }
>   
>   static struct vdpa_notification_area mlx5_get_vq_notification(struct vdpa_device *vdev, u16 idx)
> @@ -2547,13 +2544,23 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
>   
>   	/* we save one virtqueue for control virtqueue should we require it */
>   	max_vqs = MLX5_CAP_DEV_VDPA_EMULATION(mdev, max_num_virtio_queues);
> -	max_vqs = min_t(u32, max_vqs, MLX5_MAX_SUPPORTED_VQS);
> +	if (add_config->mask & BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MAX_VQP)) {
> +		if (add_config->max_virtqueues > max_vqs)
> +			return -EINVAL;
> +		max_vqs = min_t(u32, max_vqs, add_config->max_virtqueues);
> +	}
>   
>   	ndev = vdpa_alloc_device(struct mlx5_vdpa_net, mvdev.vdev, mdev->device, &mlx5_vdpa_ops,
>   				 name, false);
>   	if (IS_ERR(ndev))
>   		return PTR_ERR(ndev);
>   
> +	ndev->vqs = kcalloc(max_vqs, sizeof(*ndev->vqs), GFP_KERNEL);
> +	ndev->event_cbs = kcalloc(max_vqs + 1, sizeof(*ndev->event_cbs), GFP_KERNEL);
> +	if (!ndev->vqs || !ndev->event_cbs) {
> +		err = -ENOMEM;
> +		goto err_mtu;
> +	}
>   	ndev->mvdev.max_vqs = max_vqs;
>   	mvdev = &ndev->mvdev;
>   	mvdev->mdev = mdev;
> @@ -2676,7 +2683,8 @@ static int mlx5v_probe(struct auxiliary_device *adev,
>   	mgtdev->mgtdev.ops = &mdev_ops;
>   	mgtdev->mgtdev.device = mdev->device;
>   	mgtdev->mgtdev.id_table = id_table;
> -	mgtdev->mgtdev.config_attr_mask = (1 << VDPA_ATTR_DEV_NET_CFG_MACADDR);
> +	mgtdev->mgtdev.config_attr_mask = BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MACADDR) |
> +					  BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MAX_VQP);
>   	mgtdev->madev = madev;
>   
>   	err = vdpa_mgmtdev_register(&mgtdev->mgtdev);

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