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References: <20220613075958.511064-1-elic@nvidia.com> <20220613075958.511064-2-elic@nvidia.com>
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From:   Eugenio Perez Martin <eperezma@redhat.com>
Date:   Tue, 14 Jun 2022 08:15:05 +0200
Message-ID: <CAJaqyWc=6k0ywNPvLODcuMAzvyMwKaCHL-E5FhMTpwL=soN50A@mail.gmail.com>
Subject: Re: [PATCH 2/2] vdpa/mlx5: Initializde CVQ vringh only once
To:     Eli Cohen <elic@nvidia.com>
Cc:     Michael Tsirkin <mst@redhat.com>, Jason Wang <jasowang@redhat.com>,
        virtualization <virtualization@lists.linux-foundation.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Si-Wei Liu <si-wei.liu@oracle.com>
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On Mon, Jun 13, 2022 at 10:00 AM Eli Cohen <elic@nvidia.com> wrote:
>
> Currently, CVQ vringh is initialized inside setup_virtqueues() which is
> called every time a memory update is done. This is undesirable since it
> resets all the context of the vring, including the available and used
> indices.
>
> Move the initialization to mlx5_vdpa_set_status() when
> VIRTIO_CONFIG_S_DRIVER_OK is set.
>
> Signed-off-by: Eli Cohen <elic@nvidia.com>

Acked-by: Eugenio P=C3=A9rez <eperezma@redhat.com>

> ---
>  drivers/vdpa/mlx5/net/mlx5_vnet.c | 31 ++++++++++++++++++++-----------
>  1 file changed, 20 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/ml=
x5_vnet.c
> index 789c078ff1af..e85c1d71f4ed 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -2176,7 +2176,6 @@ static int verify_driver_features(struct mlx5_vdpa_=
dev *mvdev, u64 features)
>  static int setup_virtqueues(struct mlx5_vdpa_dev *mvdev)
>  {
>         struct mlx5_vdpa_net *ndev =3D to_mlx5_vdpa_ndev(mvdev);
> -       struct mlx5_control_vq *cvq =3D &mvdev->cvq;
>         int err;
>         int i;
>
> @@ -2186,16 +2185,6 @@ static int setup_virtqueues(struct mlx5_vdpa_dev *=
mvdev)
>                         goto err_vq;
>         }
>
> -       if (mvdev->actual_features & BIT_ULL(VIRTIO_NET_F_CTRL_VQ)) {
> -               err =3D vringh_init_iotlb(&cvq->vring, mvdev->actual_feat=
ures,
> -                                       MLX5_CVQ_MAX_ENT, false,
> -                                       (struct vring_desc *)(uintptr_t)c=
vq->desc_addr,
> -                                       (struct vring_avail *)(uintptr_t)=
cvq->driver_addr,
> -                                       (struct vring_used *)(uintptr_t)c=
vq->device_addr);
> -               if (err)
> -                       goto err_vq;
> -       }
> -
>         return 0;
>
>  err_vq:
> @@ -2468,6 +2457,21 @@ static void clear_vqs_ready(struct mlx5_vdpa_net *=
ndev)
>         ndev->mvdev.cvq.ready =3D false;
>  }
>
> +static int setup_cvq_vring(struct mlx5_vdpa_dev *mvdev)
> +{
> +       struct mlx5_control_vq *cvq =3D &mvdev->cvq;
> +       int err =3D 0;
> +
> +       if (mvdev->actual_features & BIT_ULL(VIRTIO_NET_F_CTRL_VQ))
> +               err =3D vringh_init_iotlb(&cvq->vring, mvdev->actual_feat=
ures,
> +                                       MLX5_CVQ_MAX_ENT, false,
> +                                       (struct vring_desc *)(uintptr_t)c=
vq->desc_addr,
> +                                       (struct vring_avail *)(uintptr_t)=
cvq->driver_addr,
> +                                       (struct vring_used *)(uintptr_t)c=
vq->device_addr);
> +
> +       return err;
> +}
> +
>  static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
>  {
>         struct mlx5_vdpa_dev *mvdev =3D to_mvdev(vdev);
> @@ -2480,6 +2484,11 @@ static void mlx5_vdpa_set_status(struct vdpa_devic=
e *vdev, u8 status)
>
>         if ((status ^ ndev->mvdev.status) & VIRTIO_CONFIG_S_DRIVER_OK) {
>                 if (status & VIRTIO_CONFIG_S_DRIVER_OK) {
> +                       err =3D setup_cvq_vring(mvdev);
> +                       if (err) {
> +                               mlx5_vdpa_warn(mvdev, "failed to setup co=
ntrol VQ vring\n");
> +                               goto err_setup;
> +                       }
>                         err =3D setup_driver(mvdev);
>                         if (err) {
>                                 mlx5_vdpa_warn(mvdev, "failed to setup dr=
iver\n");
> --
> 2.35.1
>