Re: [RFC PATCH V2 4/5] vhost: introduce helpers to get the size of metadata area

[Souptick Joarder]

On Wed, Mar 6, 2019 at 12:48 PM Jason Wang <jasowang@xxxxxxxxxx> wrote:
>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>

Is the change log left with any particular reason ?
> ---
>  drivers/vhost/vhost.c | 46 ++++++++++++++++++++++++++++------------------
>  1 file changed, 28 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 2025543..1015464 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -413,6 +413,27 @@ static void vhost_dev_free_iovecs(struct vhost_dev *dev)
>                 vhost_vq_free_iovecs(dev->vqs[i]);
>  }
>
> +static size_t vhost_get_avail_size(struct vhost_virtqueue *vq, int num)
> +{
> +       size_t event = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
> +
> +       return sizeof(*vq->avail) +
> +              sizeof(*vq->avail->ring) * num + event;
> +}
> +
> +static size_t vhost_get_used_size(struct vhost_virtqueue *vq, int num)
> +{
> +       size_t event = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
> +
> +       return sizeof(*vq->used) +
> +              sizeof(*vq->used->ring) * num + event;
> +}
> +
> +static size_t vhost_get_desc_size(struct vhost_virtqueue *vq, int num)
> +{
> +       return sizeof(*vq->desc) * num;
> +}
> +
>  void vhost_dev_init(struct vhost_dev *dev,
>                     struct vhost_virtqueue **vqs, int nvqs, int iov_limit)
>  {
> @@ -1253,13 +1274,9 @@ static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
>                          struct vring_used __user *used)
>
>  {
> -       size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
> -
> -       return access_ok(desc, num * sizeof *desc) &&
> -              access_ok(avail,
> -                        sizeof *avail + num * sizeof *avail->ring + s) &&
> -              access_ok(used,
> -                       sizeof *used + num * sizeof *used->ring + s);
> +       return access_ok(desc, vhost_get_desc_size(vq, num)) &&
> +              access_ok(avail, vhost_get_avail_size(vq, num)) &&
> +              access_ok(used, vhost_get_used_size(vq, num));
>  }
>
>  static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
> @@ -1311,22 +1328,18 @@ static bool iotlb_access_ok(struct vhost_virtqueue *vq,
>
>  int vq_meta_prefetch(struct vhost_virtqueue *vq)
>  {
> -       size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
>         unsigned int num = vq->num;
>
>         if (!vq->iotlb)
>                 return 1;
>
>         return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
> -                              num * sizeof(*vq->desc), VHOST_ADDR_DESC) &&
> +                              vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) &&
>                iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
> -                              sizeof *vq->avail +
> -                              num * sizeof(*vq->avail->ring) + s,
> +                              vhost_get_avail_size(vq, num),
>                                VHOST_ADDR_AVAIL) &&
>                iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
> -                              sizeof *vq->used +
> -                              num * sizeof(*vq->used->ring) + s,
> -                              VHOST_ADDR_USED);
> +                              vhost_get_used_size(vq, num), VHOST_ADDR_USED);
>  }
>  EXPORT_SYMBOL_GPL(vq_meta_prefetch);
>
> @@ -1343,13 +1356,10 @@ bool vhost_log_access_ok(struct vhost_dev *dev)
>  static bool vq_log_access_ok(struct vhost_virtqueue *vq,
>                              void __user *log_base)
>  {
> -       size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
> -
>         return vq_memory_access_ok(log_base, vq->umem,
>                                    vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
>                 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
> -                                       sizeof *vq->used +
> -                                       vq->num * sizeof *vq->used->ring + s));
> +                                 vhost_get_used_size(vq, vq->num)));
>  }
>
>  /* Can we start vq? */
> --
> 1.8.3.1
>