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Subject: Re: [PATCH 1/4] virtio-net: add definitions for host USO feature
To:     Yuri Benditovich <yuri.benditovich@daynix.com>,
        davem@davemloft.net, kuba@kernel.org, mst@redhat.com,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org
Cc:     yan@daynix.com
References: <20210511044253.469034-1-yuri.benditovich@daynix.com>
 <20210511044253.469034-2-yuri.benditovich@daynix.com>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <40938c20-5851-089b-c3c0-074bbd636970@redhat.com>
Date:   Tue, 11 May 2021 14:47:02 +0800
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在 2021/5/11 下午12:42, Yuri Benditovich 写道:
> Define feature bit and GSO type according to the VIRTIO
> specification.
>
> Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>
> ---
>   include/uapi/linux/virtio_net.h | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
> index 3f55a4215f11..a556ac735d7f 100644
> --- a/include/uapi/linux/virtio_net.h
> +++ b/include/uapi/linux/virtio_net.h
> @@ -57,6 +57,7 @@
>   					 * Steering */
>   #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
>   
> +#define VIRTIO_NET_F_HOST_USO     56	/* Host can handle USO packets */
>   #define VIRTIO_NET_F_HASH_REPORT  57	/* Supports hash report */
>   #define VIRTIO_NET_F_RSS	  60	/* Supports RSS RX steering */
>   #define VIRTIO_NET_F_RSC_EXT	  61	/* extended coalescing info */
> @@ -130,6 +131,7 @@ struct virtio_net_hdr_v1 {
>   #define VIRTIO_NET_HDR_GSO_TCPV4	1	/* GSO frame, IPv4 TCP (TSO) */
>   #define VIRTIO_NET_HDR_GSO_UDP		3	/* GSO frame, IPv4 UDP (UFO) */
>   #define VIRTIO_NET_HDR_GSO_TCPV6	4	/* GSO frame, IPv6 TCP */
> +#define VIRTIO_NET_HDR_GSO_UDP_L4	5	/* GSO frame, IPv4 UDP (USO) */


This is the gso_type not the feature actually.

I wonder what's the reason for not

1) introducing a dedicated virtio-net feature bit for this 
(VIRTIO_NET_F_GUEST_GSO_UDP_L4.
2) toggle the NETIF_F_GSO_UDP_L4  feature for tuntap based on the 
negotiated feature.

Thanks


>   #define VIRTIO_NET_HDR_GSO_ECN		0x80	/* TCP has ECN set */
>   	__u8 gso_type;
>   	__virtio16 hdr_len;	/* Ethernet + IP + tcp/udp hdrs */