Subject: Re: [PATCH 01/10] core: Split out UFO6 support

From: Vlad Yasevich <[email-masked]>
Date: Wed, 17 Dec 2014 18:31:50 -0500

On 12/17/2014 05:45 PM, Michael S. Tsirkin wrote:
> On Wed, Dec 17, 2014 at 01:20:46PM -0500, Vladislav Yasevich wrote:
>> Split IPv6 support for UFO into its own feature similiar to TSO.
>> This will later allow us to re-enable UFO support for virtio-net
>> devices.
>>
>> Signed-off-by: Vladislav Yasevich <[email-masked]>
>> ---
>>  include/linux/netdev_features.h |  7 +++++--
>>  include/linux/netdevice.h       |  1 +
>>  include/linux/skbuff.h          |  1 +
>>  net/core/dev.c                  | 35 +++++++++++++++++++----------------
>>  net/core/ethtool.c              |  2 +-
>>  5 files changed, 27 insertions(+), 19 deletions(-)
>>
>> diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h
>> index dcfdecb..a078945 100644
>> --- a/include/linux/netdev_features.h
>> +++ b/include/linux/netdev_features.h
>> @@ -48,8 +48,9 @@ enum {
>>  	NETIF_F_GSO_UDP_TUNNEL_BIT,	/* ... UDP TUNNEL with TSO */
>>  	NETIF_F_GSO_UDP_TUNNEL_CSUM_BIT,/* ... UDP TUNNEL with TSO & CSUM */
>>  	NETIF_F_GSO_MPLS_BIT,		/* ... MPLS segmentation */
>> +	NETIF_F_UFO6_BIT,		/* ... UDPv6 fragmentation */
>>  	/**/NETIF_F_GSO_LAST =		/* last bit, see GSO_MASK */
>> -		NETIF_F_GSO_MPLS_BIT,
>> +		NETIF_F_UFO6_BIT,
>>  
>>  	NETIF_F_FCOE_CRC_BIT,		/* FCoE CRC32 */
>>  	NETIF_F_SCTP_CSUM_BIT,		/* SCTP checksum offload */
>> @@ -109,6 +110,7 @@ enum {
>>  #define NETIF_F_TSO_ECN		__NETIF_F(TSO_ECN)
>>  #define NETIF_F_TSO		__NETIF_F(TSO)
>>  #define NETIF_F_UFO		__NETIF_F(UFO)
>> +#define NETIF_F_UFO6		__NETIF_F(UFO6)
>>  #define NETIF_F_VLAN_CHALLENGED	__NETIF_F(VLAN_CHALLENGED)
>>  #define NETIF_F_RXFCS		__NETIF_F(RXFCS)
>>  #define NETIF_F_RXALL		__NETIF_F(RXALL)
>> @@ -141,7 +143,7 @@ enum {
>>  
>>  /* List of features with software fallbacks. */
>>  #define NETIF_F_GSO_SOFTWARE	(NETIF_F_TSO | NETIF_F_TSO_ECN | \
>> -				 NETIF_F_TSO6 | NETIF_F_UFO)
>> +				 NETIF_F_TSO6 | NETIF_F_UFO | NETIF_F_UFO6)
>>  
>>  #define NETIF_F_GEN_CSUM	NETIF_F_HW_CSUM
>>  #define NETIF_F_V4_CSUM		(NETIF_F_GEN_CSUM | NETIF_F_IP_CSUM)
>> @@ -149,6 +151,7 @@ enum {
>>  #define NETIF_F_ALL_CSUM	(NETIF_F_V4_CSUM | NETIF_F_V6_CSUM)
>>  
>>  #define NETIF_F_ALL_TSO 	(NETIF_F_TSO | NETIF_F_TSO6 | NETIF_F_TSO_ECN)
>> +#define NETIF_F_ALL_UFO		(NETIF_F_UFO | NETIF_F_UFO6)
>>  
>>  #define NETIF_F_ALL_FCOE	(NETIF_F_FCOE_CRC | NETIF_F_FCOE_MTU | \
>>  				 NETIF_F_FSO)
>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>> index 74fd5d3..86af10a 100644
>> --- a/include/linux/netdevice.h
>> +++ b/include/linux/netdevice.h
>> @@ -3559,6 +3559,7 @@ static inline bool net_gso_ok(netdev_features_t features, int gso_type)
>>  	/* check flags correspondence */
>>  	BUILD_BUG_ON(SKB_GSO_TCPV4   != (NETIF_F_TSO >> NETIF_F_GSO_SHIFT));
>>  	BUILD_BUG_ON(SKB_GSO_UDP     != (NETIF_F_UFO >> NETIF_F_GSO_SHIFT));
>> +	BUILD_BUG_ON(SKB_GSO_UDP6    != (NETIF_F_UFO6 >> NETIF_F_GSO_SHIFT));
>>  	BUILD_BUG_ON(SKB_GSO_DODGY   != (NETIF_F_GSO_ROBUST >> NETIF_F_GSO_SHIFT));
>>  	BUILD_BUG_ON(SKB_GSO_TCP_ECN != (NETIF_F_TSO_ECN >> NETIF_F_GSO_SHIFT));
>>  	BUILD_BUG_ON(SKB_GSO_TCPV6   != (NETIF_F_TSO6 >> NETIF_F_GSO_SHIFT));
>> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
>> index 6c8b6f6..8538b67 100644
>> --- a/include/linux/skbuff.h
>> +++ b/include/linux/skbuff.h
>> @@ -372,6 +372,7 @@ enum {
>>  
>>  	SKB_GSO_MPLS = 1 << 12,
>>  
>> +	SKB_GSO_UDP6 = 1 << 13
>>  };
>>  
>>  #if BITS_PER_LONG > 32
> 
> So this implies anything getting GSO packets e.g.
> from userspace now needs to check IP version to
> set GSO type correctly.
> 
> I think you missed some places that do this, e.g. af_packet
> sockets.
> 

I looked at af_packet sockets and they set this only in the event
vnet header has been used with a GSO type.  In this case, the user
already knows the the type.

It is true that with this series af_packets now can't do IPv6 UFO
since there is no VIRTIO_NET_HDR_GSO_UDPV6 yet.

I suppose we could do something similar there as we do in tun code/macvtap code.
If that's the case, it currently broken as well.

-vlad

> 
>> diff --git a/net/core/dev.c b/net/core/dev.c
>> index 945bbd0..fa4d2ee 100644
>> --- a/net/core/dev.c
>> +++ b/net/core/dev.c
>> @@ -5929,6 +5929,12 @@ static netdev_features_t netdev_fix_features(struct net_device *dev,
>>  		features &= ~NETIF_F_ALL_TSO;
>>  	}
>>  
>> +	/* UFO requires that SG is present as well */
>> +	if ((features & NETIF_F_ALL_UFO) && !(features & NETIF_F_SG)) {
>> +		netdev_dbg(dev, "Dropping UFO features since no SG feature.\n");
>> +		features &= ~NETIF_F_ALL_UFO;
>> +	}
>> +
>>  	if ((features & NETIF_F_TSO) && !(features & NETIF_F_HW_CSUM) &&
>>  					!(features & NETIF_F_IP_CSUM)) {
>>  		netdev_dbg(dev, "Dropping TSO features since no CSUM feature.\n");
>> @@ -5952,24 +5958,21 @@ static netdev_features_t netdev_fix_features(struct net_device *dev,
>>  		features &= ~NETIF_F_GSO;
>>  	}
>>  
>> -	/* UFO needs SG and checksumming */
>> -	if (features & NETIF_F_UFO) {
>> -		/* maybe split UFO into V4 and V6? */
>> -		if (!((features & NETIF_F_GEN_CSUM) ||
>> -		    (features & (NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM))
>> -			    == (NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM))) {
>> -			netdev_dbg(dev,
>> -				"Dropping NETIF_F_UFO since no checksum offload features.\n");
>> -			features &= ~NETIF_F_UFO;
>> -		}
>> -
>> -		if (!(features & NETIF_F_SG)) {
>> -			netdev_dbg(dev,
>> -				"Dropping NETIF_F_UFO since no NETIF_F_SG feature.\n");
>> -			features &= ~NETIF_F_UFO;
>> -		}
>> +	/* UFO also needs checksumming */
>> +	if ((features & NETIF_F_UFO) && !(features & NETIF_F_GEN_CSUM) &&
>> +					!(features & NETIF_F_IP_CSUM)) {
>> +		netdev_dbg(dev,
>> +			   "Dropping NETIF_F_UFO since no checksum offload features.\n");
>> +		features &= ~NETIF_F_UFO;
>> +	}
>> +	if ((features & NETIF_F_UFO6) && !(features & NETIF_F_GEN_CSUM) &&
>> +					 !(features & NETIF_F_IPV6_CSUM)) {
>> +		netdev_dbg(dev,
>> +			   "Dropping NETIF_F_UFO6 since no checksum offload features.\n");
>> +		features &= ~NETIF_F_UFO6;
>>  	}
>>  
>> +
>>  #ifdef CONFIG_NET_RX_BUSY_POLL
>>  	if (dev->netdev_ops->ndo_busy_poll)
>>  		features |= NETIF_F_BUSY_POLL;
>> diff --git a/net/core/ethtool.c b/net/core/ethtool.c
>> index 06dfb29..93eff41 100644
>> --- a/net/core/ethtool.c
>> +++ b/net/core/ethtool.c
>> @@ -223,7 +223,7 @@ static netdev_features_t ethtool_get_feature_mask(u32 eth_cmd)
>>  		return NETIF_F_ALL_TSO;
>>  	case ETHTOOL_GUFO:
>>  	case ETHTOOL_SUFO:
>> -		return NETIF_F_UFO;
>> +		return NETIF_F_ALL_UFO;
>>  	case ETHTOOL_GGSO:
>>  	case ETHTOOL_SGSO:
>>  		return NETIF_F_GSO;
>> -- 
>> 1.9.3