Re: [PATCH 1/3] virtio-net: fix max vring buf size when set ring num

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

On Mon, Sep 19, 2022 at 05:39:13AM -0400, liuhaiwei wrote:

Pls write a commit log. Explain what is this patch fixing
and why this is the correct fix.


> Signed-off-by: liuhaiwei <liuhaiwei9699@126.com>

Please use your full first and last name.
No anonymous contributions.

> ---
>  hw/virtio/virtio.c         | 10 +++++++---
>  include/hw/virtio/virtio.h |  1 +
>  2 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 5d607aeaa0..d93c20d747 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -2286,13 +2286,17 @@ void virtio_queue_set_rings(VirtIODevice *vdev, int n, hwaddr desc,
>  
>  void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
>  {
> +    int vq_max_size = VIRTQUEUE_MAX_SIZE;
> +    if (!strcmp(vdev->name, "virtio-net")) {
> +        vq_max_size = VIRTIO_NET_VQ_MAX_SIZE;
> +    }
> +


Any less ugly ways to do this?

>      /* Don't allow guest to flip queue between existent and
>       * nonexistent states, or to set it to an invalid size.
>       */
>      if (!!num != !!vdev->vq[n].vring.num ||
> -        num > VIRTQUEUE_MAX_SIZE ||
> -        num < 0) {
> -        return;
> +        num > vq_max_size || num < 0) {
> +	    return;
>      }
>      vdev->vq[n].vring.num = num;
>  }
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index db1c0ddf6b..1f4d2eb5d7 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -50,6 +50,7 @@ size_t virtio_feature_get_config_size(const VirtIOFeature *features,
>  typedef struct VirtQueue VirtQueue;
>  
>  #define VIRTQUEUE_MAX_SIZE 1024
> +#define VIRTIO_NET_VQ_MAX_SIZE (4096)



>  
>  typedef struct VirtQueueElement
>  {
> -- 
> 2.27.0