Subject: Re: [PATCH v6 41/46] macvtap: TUN_VNET_HDR support

From: Jason Wang <[email-masked]>
Date: Fri, 28 Nov 2014 08:32:11 +0008

On Fri, Nov 28, 2014 at 4:11 AM, Michael S. Tsirkin <[email-masked]> 
wrote:
> Signed-off-by: Michael S. Tsirkin <[email-masked]>
> ---
>  drivers/net/macvtap.c | 68 
> ++++++++++++++++++++++++++++++++-------------------
>  1 file changed, 43 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
> index 880cc09..af90ab5 100644
> --- a/drivers/net/macvtap.c
> +++ b/drivers/net/macvtap.c
> @@ -45,6 +45,18 @@ struct macvtap_queue {
>  	struct list_head next;
>  };
>  
> +#define MACVTAP_FEATURES (IFF_VNET_HDR | IFF_VNET_LE | 
> IFF_MULTI_QUEUE)
> +
> +static inline u16 macvtap16_to_cpu(struct macvtap_queue *q, 
> __virtio16 val)
> +{
> +	return __virtio16_to_cpu(q->flags & IFF_VNET_LE, val);
> +}
> +
> +static inline __virtio16 cpu_to_macvtap16(struct macvtap_queue *q, 
> u16 val)
> +{
> +	return __cpu_to_virtio16(q->flags & IFF_VNET_LE, val);
> +}
> +
>  static struct proto macvtap_proto = {
>  	.name = "macvtap",
>  	.owner = THIS_MODULE,
> @@ -557,7 +569,8 @@ static inline struct sk_buff 
> *macvtap_alloc_skb(struct sock *sk, size_t prepad,
>   * macvtap_skb_from_vnet_hdr and macvtap_skb_to_vnet_hdr should
>   * be shared with the tun/tap driver.
>   */
> -static int macvtap_skb_from_vnet_hdr(struct sk_buff *skb,
> +static int macvtap_skb_from_vnet_hdr(struct macvtap_queue *q,
> +				     struct sk_buff *skb,
>  				     struct virtio_net_hdr *vnet_hdr)
>  {
>  	unsigned short gso_type = 0;
> @@ -588,13 +601,13 @@ static int macvtap_skb_from_vnet_hdr(struct 
> sk_buff *skb,
>  	}
>  
>  	if (vnet_hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
> -		if (!skb_partial_csum_set(skb, vnet_hdr->csum_start,
> -					  vnet_hdr->csum_offset))
> +		if (!skb_partial_csum_set(skb, macvtap16_to_cpu(q, 
> vnet_hdr->csum_start),
> +					  macvtap16_to_cpu(q, vnet_hdr->csum_offset)))
>  			return -EINVAL;
>  	}
>  
>  	if (vnet_hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
> -		skb_shinfo(skb)->gso_size = vnet_hdr->gso_size;
> +		skb_shinfo(skb)->gso_size = macvtap16_to_cpu(q, 
> vnet_hdr->gso_size);
>  		skb_shinfo(skb)->gso_type = gso_type;
>  
>  		/* Header must be checked, and gso_segs computed. */
> @@ -604,8 +617,9 @@ static int macvtap_skb_from_vnet_hdr(struct 
> sk_buff *skb,
>  	return 0;
>  }
>  
> -static void macvtap_skb_to_vnet_hdr(const struct sk_buff *skb,
> -				   struct virtio_net_hdr *vnet_hdr)
> +static void macvtap_skb_to_vnet_hdr(struct macvtap_queue *q,
> +				    const struct sk_buff *skb,
> +				    struct virtio_net_hdr *vnet_hdr)
>  {
>  	memset(vnet_hdr, 0, sizeof(*vnet_hdr));
>  
> @@ -613,8 +627,8 @@ static void macvtap_skb_to_vnet_hdr(const struct 
> sk_buff *skb,
>  		struct skb_shared_info *sinfo = skb_shinfo(skb);
>  
>  		/* This is a hint as to how much should be linear. */
> -		vnet_hdr->hdr_len = skb_headlen(skb);
> -		vnet_hdr->gso_size = sinfo->gso_size;
> +		vnet_hdr->hdr_len = cpu_to_macvtap16(q, skb_headlen(skb));
> +		vnet_hdr->gso_size = cpu_to_macvtap16(q, sinfo->gso_size);
>  		if (sinfo->gso_type & SKB_GSO_TCPV4)
>  			vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
>  		else if (sinfo->gso_type & SKB_GSO_TCPV6)
> @@ -628,10 +642,13 @@ static void macvtap_skb_to_vnet_hdr(const 
> struct sk_buff *skb,
>  
>  	if (skb->ip_summed == CHECKSUM_PARTIAL) {
>  		vnet_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
> -		vnet_hdr->csum_start = skb_checksum_start_offset(skb);
>  		if (vlan_tx_tag_present(skb))
> -			vnet_hdr->csum_start += VLAN_HLEN;
> -		vnet_hdr->csum_offset = skb->csum_offset;
> +			vnet_hdr->csum_start = cpu_to_macvtap16(q,
> +				skb_checksum_start_offset(skb) + VLAN_HLEN);
> +		else
> +			vnet_hdr->csum_start = cpu_to_macvtap16(q,
> +				skb_checksum_start_offset(skb));
> +		vnet_hdr->csum_offset = cpu_to_macvtap16(q, skb->csum_offset);
>  	} else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
>  		vnet_hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
>  	} /* else everything is zero */
> @@ -666,12 +683,14 @@ static ssize_t macvtap_get_user(struct 
> macvtap_queue *q, struct msghdr *m,
>  		if (err < 0)
>  			goto err;
>  		if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
> -		     vnet_hdr.csum_start + vnet_hdr.csum_offset + 2 >
> -							vnet_hdr.hdr_len)
> -			vnet_hdr.hdr_len = vnet_hdr.csum_start +
> -						vnet_hdr.csum_offset + 2;
> +		     macvtap16_to_cpu(q, vnet_hdr.csum_start) +
> +		     macvtap16_to_cpu(q, vnet_hdr.csum_offset) + 2 >
> +			     macvtap16_to_cpu(q, vnet_hdr.hdr_len))
> +			vnet_hdr.hdr_len = cpu_to_macvtap16(q,
> +				 macvtap16_to_cpu(q, vnet_hdr.csum_start) +
> +				 macvtap16_to_cpu(q, vnet_hdr.csum_offset) + 2);
>  		err = -EINVAL;
> -		if (vnet_hdr.hdr_len > len)
> +		if (macvtap16_to_cpu(q, vnet_hdr.hdr_len) > len)
>  			goto err;
>  	}
>  
> @@ -684,7 +703,8 @@ static ssize_t macvtap_get_user(struct 
> macvtap_queue *q, struct msghdr *m,
>  		goto err;
>  
>  	if (m && m->msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) {
> -		copylen = vnet_hdr.hdr_len ? vnet_hdr.hdr_len : GOODCOPY_LEN;
> +		copylen = vnet_hdr.hdr_len ?
> +			macvtap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN;
>  		if (copylen > good_linear)
>  			copylen = good_linear;
>  		linear = copylen;
> @@ -695,10 +715,10 @@ static ssize_t macvtap_get_user(struct 
> macvtap_queue *q, struct msghdr *m,
>  
>  	if (!zerocopy) {
>  		copylen = len;
> -		if (vnet_hdr.hdr_len > good_linear)
> +		if (macvtap16_to_cpu(q, vnet_hdr.hdr_len) > good_linear)
>  			linear = good_linear;
>  		else
> -			linear = vnet_hdr.hdr_len;
> +			linear = macvtap16_to_cpu(q, vnet_hdr.hdr_len);
>  	}
>  
>  	skb = macvtap_alloc_skb(&q->sk, NET_IP_ALIGN, copylen,
> @@ -725,7 +745,7 @@ static ssize_t macvtap_get_user(struct 
> macvtap_queue *q, struct msghdr *m,
>  	skb->protocol = eth_hdr(skb)->h_proto;
>  
>  	if (vnet_hdr_len) {
> -		err = macvtap_skb_from_vnet_hdr(skb, &vnet_hdr);
> +		err = macvtap_skb_from_vnet_hdr(q, skb, &vnet_hdr);
>  		if (err)
>  			goto err_kfree;
>  	}
> @@ -791,7 +811,7 @@ static ssize_t macvtap_put_user(struct 
> macvtap_queue *q,
>  		if ((len -= vnet_hdr_len) < 0)
>  			return -EINVAL;
>  
> -		macvtap_skb_to_vnet_hdr(skb, &vnet_hdr);
> +		macvtap_skb_to_vnet_hdr(q, skb, &vnet_hdr);
>  
>  		if (memcpy_toiovecend(iv, (void *)&vnet_hdr, 0, sizeof(vnet_hdr)))
>  			return -EFAULT;
> @@ -1003,8 +1023,7 @@ static long macvtap_ioctl(struct file *file, 
> unsigned int cmd,
>  			return -EFAULT;
>  
>  		ret = 0;
> -		if ((u & ~(IFF_VNET_HDR | IFF_MULTI_QUEUE)) !=
> -		    (IFF_NO_PI | IFF_TAP))
> +		if ((u & ~MACVTAP_FEATURES) != (IFF_NO_PI | IFF_TAP))
>  			ret = -EINVAL;
>  		else
>  			q->flags = u;
> @@ -1036,8 +1055,7 @@ static long macvtap_ioctl(struct file *file, 
> unsigned int cmd,
>  		return ret;
>  
>  	case TUNGETFEATURES:
> -		if (put_user(IFF_TAP | IFF_NO_PI | IFF_VNET_HDR |
> -			     IFF_MULTI_QUEUE, up))
> +		if (put_user(IFF_TAP | IFF_NO_PI | MACVTAP_FEATURES, up))
>  			return -EFAULT;
>  		return 0;
>  
> -- 
> MST

Reviewed-by: Jason Wang <[email-masked]>

btw, title should be macvtap: IFF_VNET_LE support