On Thu, Feb 12, 2026 at 06:33:40PM +0530, Srujana Challa wrote:
> Replace hardcoded RSS max key size limit with a type based definition.
> Add validation for RSS key size against spec minimum (40 bytes). When
> validation fails, gracefully disable RSS features and continue
> initialization rather than failing completely.
>
> Cc: [email protected]
> Fixes: 3f7d9c1964fc ("virtio_net: Add hash_key_length check")
> Signed-off-by: Srujana Challa <[email protected]>
>
> v3:
> - Moved RSS key validation checks to virtnet_validate.
> - Add fixes: tag and CC -stable
> ---
> drivers/net/virtio_net.c | 29 +++++++++++++++++++++--------
> 1 file changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index db88dcaefb20..e61cea50dcab 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -381,7 +381,9 @@ struct receive_queue {
> struct xdp_buff **xsk_buffs;
> };
>
> -#define VIRTIO_NET_RSS_MAX_KEY_SIZE 40
> +#define VIRTIO_NET_RSS_MAX_KEY_SIZE \
> + (type_max(((struct virtio_net_config *)0)->rss_max_key_size) + 1)
+1 here really unintuitive.
It does not look like it's still used, though?
> +#define VIRTIO_NET_RSS_MIN_KEY_SIZE 40
>
> /* Control VQ buffers: protected by the rtnl lock */
> struct control_buf {
> @@ -6627,6 +6629,24 @@ static int virtnet_validate(struct virtio_device *vdev)
> __virtio_clear_bit(vdev, VIRTIO_NET_F_STANDBY);
> }
>
> + if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS) ||
> + virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT)) {
> + u8 key_sz = virtio_cread8(vdev,
> + offsetof(struct virtio_net_config,
> + rss_max_key_size));
> + /* Spec requires at least 40 bytes */
move the define here then?
> + if (key_sz < VIRTIO_NET_RSS_MIN_KEY_SIZE) {
> + dev_warn(&vdev->dev,
> + "rss_max_key_size=%u is less than spec minimum
> %u, disabling RSS\n",
> + key_sz, VIRTIO_NET_RSS_MIN_KEY_SIZE);
> + if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS))
> + __virtio_clear_bit(vdev, VIRTIO_NET_F_RSS);
> + if (virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT))
> + __virtio_clear_bit(vdev,
> + VIRTIO_NET_F_HASH_REPORT);
why not clear them unconditionally?
> + }
> + }
> +
> return 0;
> }
>
> @@ -6839,13 +6859,6 @@ static int virtnet_probe(struct virtio_device *vdev)
> if (vi->has_rss || vi->has_rss_hash_report) {
> vi->rss_key_size =
> virtio_cread8(vdev, offsetof(struct virtio_net_config,
> rss_max_key_size));
> - if (vi->rss_key_size > VIRTIO_NET_RSS_MAX_KEY_SIZE) {
> - dev_err(&vdev->dev, "rss_max_key_size=%u exceeds the
> limit %u.\n",
> - vi->rss_key_size, VIRTIO_NET_RSS_MAX_KEY_SIZE);
> - err = -EINVAL;
> - goto free;
> - }
> -
> vi->rss_hash_types_supported =
> virtio_cread32(vdev, offsetof(struct virtio_net_config,
> supported_hash_types));
> vi->rss_hash_types_supported &=
> --
> 2.25.1
