linux-kernel - Re: [PATCH] vdpa/mlx5: Fix MQ to support non power of two num queues

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Message-ID: <CACGkMEsMm8nfsFNa=B-Zv-fukNex+M8vVoKOfjpr-TxgKXnVhA@mail.gmail.com>
Date:   Wed, 14 Sep 2022 12:44:14 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Eli Cohen <elic@...dia.com>
Cc:     mst <mst@...hat.com>, eperezma <eperezma@...hat.com>,
        Si-Wei Liu <si-wei.liu@...cle.com>,
        virtualization <virtualization@...ts.linux-foundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] vdpa/mlx5: Fix MQ to support non power of two num queues

On Mon, Sep 12, 2022 at 8:50 PM Eli Cohen <elic@...dia.com> wrote:
>
> RQT objects require that a power of two value be configured for both
> rqt_max_size and rqt_actual size.
>
> For create_rqt, make sure to round up to the power of two the value of
> given by the user who created the vdpa device and given by
> ndev->rqt_size. The actual size is also rounded up to the power of two
> using the current number of VQs given by ndev->cur_num_vqs.
>
> Same goes with modify_rqt where we need to make sure act size is power
> of two based on the new number of QPs.
>
> Without this patch, attempt to create a device with non power of two QPs
> would result in error from firmware.
>
> Fixes: 52893733f2c5 ("vdpa/mlx5: Add multiqueue support")
> Signed-off-by: Eli Cohen <elic@...dia.com>

Acked-by: Jason Wang <jasowang@...hat.com>

> ---
>  drivers/vdpa/mlx5/net/mlx5_vnet.c | 17 ++++++++++-------
>  1 file changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index ed100a35e596..90913365def4 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -1320,6 +1320,8 @@ static void teardown_vq(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *
>
>  static int create_rqt(struct mlx5_vdpa_net *ndev)
>  {
> +       int rqt_table_size = roundup_pow_of_two(ndev->rqt_size);
> +       int act_sz = roundup_pow_of_two(ndev->cur_num_vqs / 2);
>         __be32 *list;
>         void *rqtc;
>         int inlen;
> @@ -1327,7 +1329,7 @@ static int create_rqt(struct mlx5_vdpa_net *ndev)
>         int i, j;
>         int err;
>
> -       inlen = MLX5_ST_SZ_BYTES(create_rqt_in) + ndev->rqt_size * MLX5_ST_SZ_BYTES(rq_num);
> +       inlen = MLX5_ST_SZ_BYTES(create_rqt_in) + rqt_table_size * MLX5_ST_SZ_BYTES(rq_num);
>         in = kzalloc(inlen, GFP_KERNEL);
>         if (!in)
>                 return -ENOMEM;
> @@ -1336,12 +1338,12 @@ static int create_rqt(struct mlx5_vdpa_net *ndev)
>         rqtc = MLX5_ADDR_OF(create_rqt_in, in, rqt_context);
>
>         MLX5_SET(rqtc, rqtc, list_q_type, MLX5_RQTC_LIST_Q_TYPE_VIRTIO_NET_Q);
> -       MLX5_SET(rqtc, rqtc, rqt_max_size, ndev->rqt_size);
> +       MLX5_SET(rqtc, rqtc, rqt_max_size, rqt_table_size);
>         list = MLX5_ADDR_OF(rqtc, rqtc, rq_num[0]);
> -       for (i = 0, j = 0; i < ndev->rqt_size; i++, j += 2)
> +       for (i = 0, j = 0; i < act_sz; i++, j += 2)
>                 list[i] = cpu_to_be32(ndev->vqs[j % ndev->cur_num_vqs].virtq_id);
>
> -       MLX5_SET(rqtc, rqtc, rqt_actual_size, ndev->rqt_size);
> +       MLX5_SET(rqtc, rqtc, rqt_actual_size, act_sz);
>         err = mlx5_vdpa_create_rqt(&ndev->mvdev, in, inlen, &ndev->res.rqtn);
>         kfree(in);
>         if (err)
> @@ -1354,6 +1356,7 @@ static int create_rqt(struct mlx5_vdpa_net *ndev)
>
>  static int modify_rqt(struct mlx5_vdpa_net *ndev, int num)
>  {
> +       int act_sz = roundup_pow_of_two(num / 2);
>         __be32 *list;
>         void *rqtc;
>         int inlen;
> @@ -1361,7 +1364,7 @@ static int modify_rqt(struct mlx5_vdpa_net *ndev, int num)
>         int i, j;
>         int err;
>
> -       inlen = MLX5_ST_SZ_BYTES(modify_rqt_in) + ndev->rqt_size * MLX5_ST_SZ_BYTES(rq_num);
> +       inlen = MLX5_ST_SZ_BYTES(modify_rqt_in) + act_sz * MLX5_ST_SZ_BYTES(rq_num);
>         in = kzalloc(inlen, GFP_KERNEL);
>         if (!in)
>                 return -ENOMEM;
> @@ -1372,10 +1375,10 @@ static int modify_rqt(struct mlx5_vdpa_net *ndev, int num)
>         MLX5_SET(rqtc, rqtc, list_q_type, MLX5_RQTC_LIST_Q_TYPE_VIRTIO_NET_Q);
>
>         list = MLX5_ADDR_OF(rqtc, rqtc, rq_num[0]);
> -       for (i = 0, j = 0; i < ndev->rqt_size; i++, j += 2)
> +       for (i = 0, j = 0; i < act_sz; i++, j = j + 2)
>                 list[i] = cpu_to_be32(ndev->vqs[j % num].virtq_id);
>
> -       MLX5_SET(rqtc, rqtc, rqt_actual_size, ndev->rqt_size);
> +       MLX5_SET(rqtc, rqtc, rqt_actual_size, act_sz);
>         err = mlx5_vdpa_modify_rqt(&ndev->mvdev, in, inlen, ndev->res.rqtn);
>         kfree(in);
>         if (err)
> --
> 2.35.1
>