Re: [PATCH net-next v9 6/6] vhost/net: Support VIRTIO_NET_F_HASH_REPORT

[Jason Wang]

On Fri, Mar 7, 2025 at 7:02 PM Akihiko Odaki <akihiko.odaki@xxxxxxxxxx> wrote:
>
> VIRTIO_NET_F_HASH_REPORT allows to report hash values calculated on the
> host. When VHOST_NET_F_VIRTIO_NET_HDR is employed, it will report no
> hash values (i.e., the hash_report member is always set to
> VIRTIO_NET_HASH_REPORT_NONE). Otherwise, the values reported by the
> underlying socket will be reported.
>
> VIRTIO_NET_F_HASH_REPORT requires VIRTIO_F_VERSION_1.
>
> Signed-off-by: Akihiko Odaki <akihiko.odaki@xxxxxxxxxx>
> Tested-by: Lei Yang <leiyang@xxxxxxxxxx>
> ---
>  drivers/vhost/net.c | 49 +++++++++++++++++++++++++++++--------------------
>  1 file changed, 29 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index b9b9e9d40951856d881d77ac74331d914473cd56..16b241b44f89820a42c302f3586ea6bb5e0d4289 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -73,6 +73,7 @@ enum {
>         VHOST_NET_FEATURES = VHOST_FEATURES |
>                          (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
>                          (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
> +                        (1ULL << VIRTIO_NET_F_HASH_REPORT) |
>                          (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
>                          (1ULL << VIRTIO_F_RING_RESET)
>  };
> @@ -1097,9 +1098,11 @@ static void handle_rx(struct vhost_net *net)
>                 .msg_controllen = 0,
>                 .msg_flags = MSG_DONTWAIT,
>         };
> -       struct virtio_net_hdr hdr = {
> -               .flags = 0,
> -               .gso_type = VIRTIO_NET_HDR_GSO_NONE
> +       struct virtio_net_hdr_v1_hash hdr = {
> +               .hdr = {
> +                       .flags = 0,
> +                       .gso_type = VIRTIO_NET_HDR_GSO_NONE
> +               }
>         };
>         size_t total_len = 0;
>         int err, mergeable;
> @@ -1110,7 +1113,6 @@ static void handle_rx(struct vhost_net *net)
>         bool set_num_buffers;
>         struct socket *sock;
>         struct iov_iter fixup;
> -       __virtio16 num_buffers;
>         int recv_pkts = 0;
>
>         mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_RX);
> @@ -1191,30 +1193,30 @@ static void handle_rx(struct vhost_net *net)
>                         vhost_discard_vq_desc(vq, headcount);
>                         continue;
>                 }
> +               hdr.hdr.num_buffers = cpu_to_vhost16(vq, headcount);
>                 /* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
>                 if (unlikely(vhost_hlen)) {
> -                       if (copy_to_iter(&hdr, sizeof(hdr),
> -                                        &fixup) != sizeof(hdr)) {
> +                       if (copy_to_iter(&hdr, vhost_hlen,
> +                                        &fixup) != vhost_hlen) {
>                                 vq_err(vq, "Unable to write vnet_hdr "
>                                        "at addr %p\n", vq->iov->iov_base);
>                                 goto out;

Is this an "issue" specific to RSS/HASH? If it's not, we need a separate patch.

Honestly, I'm not sure if it's too late to fix this.

Others look fine.

Thanks