thr3ads.net - Linux Virtualization - [PATCH V2 net-next 0/6] virtio-net: Add SCTP checksum offload support [May 2018]

If this information is useful, please help other people find it:
Share via:

Vladislav Yasevich

2018-May-02 02:07 UTC

[PATCH V2 net-next 0/6] virtio-net: Add SCTP checksum offload support

Now that we have SCTP offload capabilities in the kernel, we can add
them to virtio as well.  First step is SCTP checksum.

We need a new freature in virtio to negotiate this support since
SCTP is excluded with the stardard checksum and requires a little
bit extra.  This series proposes VIRTIO_NET_F_SCTP_CSUM feature bit.

As the "little bit extra",  the kernel uses a new bit in the skb
(skb->csum_not_inet) to determine whether to use standard inet checksum
or the SCTP CRC32c checksum.  This bit has to be communicated between
the host and the guest.  This bit is carried in the vnet header.

Tap and macvtap support is added through an extra feature for the
TUNSETOFFLOAD ioctl.  Additionally macvtap will no correctly
do sctp checksumming if the receive doesn't support SCTP offload.
This also turns on sctp offloading for macvlan devices.

As for the perf numbers, I am seeing about a 5% increase in vm-to-vm
and vm-to-hos throughput which is the same as manually disabling
sctp checksumming,since this is exactly what we are emulatting.
Sending outside the host,  the increase about 2.5-3%.

Since v1:
  - Fixed some old patch bugs that snuck in.
  - virtio feature bits moved to high bits
  - distinguish between GUEST and HOST features
  - Fixed offload control command to control sctp checksum offload
  - added ipvlan support

Vladislav Yasevich (6):
  virtio: Add support for SCTP checksum offloading
  sctp: Handle sctp packets with CHECKSUM_PARTIAL
  sctp: Build sctp offload support into the base kernel
  tun: Add support for SCTP checksum offload
  macvlan/macvtap: Add support for SCTP checksum offload.
  ipvlan: Add support for SCTP checksum offload

 drivers/net/ipvlan/ipvlan_main.c |  3 ++-
 drivers/net/macvlan.c            |  5 +++--
 drivers/net/tap.c                |  8 +++++---
 drivers/net/tun.c                |  7 ++++++-
 drivers/net/virtio_net.c         | 14 +++++++++++++-
 include/linux/virtio_net.h       |  6 ++++++
 include/net/sctp/sctp.h          |  5 -----
 include/uapi/linux/if_tun.h      |  1 +
 include/uapi/linux/virtio_net.h  |  5 +++++
 net/Kconfig                      |  1 +
 net/sctp/Kconfig                 |  1 -
 net/sctp/Makefile                |  3 ++-
 net/sctp/input.c                 | 11 ++++++++++-
 net/sctp/offload.c               |  4 +++-
 net/sctp/protocol.c              |  3 ---
 15 files changed, 57 insertions(+), 20 deletions(-)

-- 
2.9.5

Vladislav Yasevich

2018-May-02 02:07 UTC

head link

[PATCH V2 net-next 1/6] virtio: Add support for SCTP checksum offloading

To support SCTP checksum offloading, we need to add a new feature
to virtio_net, so we can negotiate support between the hypervisor
and the guest.
The HOST feature bit signifies offloading support for transmit and
enables device offload features.
The GUEST feature bit signifies offloading support of recieve and
is currently only used by the driver in case of xdp.  

That patch also adds an addition virtio_net header flag which
mirrors the skb->csum_not_inet flag.  This flags is used to indicate
that is this an SCTP packet that needs its checksum computed by the
lower layer.  In this case, the lower layer is the host hypervisor or
possibly HW nic that supporst CRC32c offload.

In the case that GUEST feature bit is flag, it will be possible to
receive a virtio_net header with this bit set, which will set the
corresponding skb bit.  SCTP protocol will be updated to correctly
deal with it.

Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
---
 drivers/net/virtio_net.c        | 14 +++++++++++++-
 include/linux/virtio_net.h      |  6 ++++++
 include/uapi/linux/virtio_net.h |  5 +++++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 7b187ec..34af280 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2148,6 +2148,8 @@ static int virtnet_clear_guest_offloads(struct
virtnet_info *vi)
 
 	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_CSUM))
 		offloads = 1ULL << VIRTIO_NET_F_GUEST_CSUM;
+	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_SCTP_CSUM))
+		offloads |= 1ULL << VIRTIO_NET_F_GUEST_SCTP_CSUM;
 
 	return virtnet_set_guest_offloads(vi, offloads);
 }
@@ -2160,6 +2162,8 @@ static int virtnet_restore_guest_offloads(struct
virtnet_info *vi)
 		return 0;
 	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_CSUM))
 		offloads |= 1ULL << VIRTIO_NET_F_GUEST_CSUM;
+	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_SCTP_CSUM))
+		offloads |= 1ULL << VIRTIO_NET_F_GUEST_SCTP_CSUM;
 
 	return virtnet_set_guest_offloads(vi, offloads);
 }
@@ -2724,6 +2728,7 @@ static int virtnet_probe(struct virtio_device *vdev)
 	/* Do we support "hardware" checksums? */
 	if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
 		/* This opens up the world of extra features. */
+
 		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG;
 		if (csum)
 			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;
@@ -2746,9 +2751,15 @@ static int virtnet_probe(struct virtio_device *vdev)
 			dev->features |= dev->hw_features & NETIF_F_ALL_TSO;
 		/* (!csum && gso) case will be fixed by register_netdev() */
 	}
+
 	if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_CSUM))
 		dev->features |= NETIF_F_RXCSUM;
 
+	if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_SCTP_CSUM)) {
+		dev->hw_features |= NETIF_F_SCTP_CRC;
+		dev->features |= NETIF_F_SCTP_CRC;
+	}
+
 	dev->vlan_features = dev->features;
 
 	/* MTU range: 68 - 65535 */
@@ -2962,7 +2973,8 @@ static struct virtio_device_id id_table[] = {
 	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, \
 	VIRTIO_NET_F_CTRL_MAC_ADDR, \
 	VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
-	VIRTIO_NET_F_SPEED_DUPLEX
+	VIRTIO_NET_F_SPEED_DUPLEX, \
+	VIRTIO_NET_F_HOST_SCTP_CSUM, VIRTIO_NET_F_GUEST_SCTP_CSUM
 
 static unsigned int features[] = {
 	VIRTNET_FEATURES,
diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index f144216..28fffdc 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -39,6 +39,9 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
 
 		if (!skb_partial_csum_set(skb, start, off))
 			return -EINVAL;
+
+		if (hdr->flags & VIRTIO_NET_HDR_F_CSUM_NOT_INET)
+			skb->csum_not_inet = 1;
 	}
 
 	if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
@@ -91,6 +94,9 @@ static inline int virtio_net_hdr_from_skb(const struct sk_buff
*skb,
 				skb_checksum_start_offset(skb));
 		hdr->csum_offset = __cpu_to_virtio16(little_endian,
 				skb->csum_offset);
+
+		if (skb->csum_not_inet)
+			hdr->flags |= VIRTIO_NET_HDR_F_CSUM_NOT_INET;
 	} else if (has_data_valid &&
 		   skb->ip_summed == CHECKSUM_UNNECESSARY) {
 		hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
index 5de6ed3..9dfca1a 100644
--- a/include/uapi/linux/virtio_net.h
+++ b/include/uapi/linux/virtio_net.h
@@ -57,6 +57,10 @@
 					 * Steering */
 #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
 
+#define VIRTIO_NET_F_GUEST_SCTP_CSUM  61 /* Guest handles SCTP pks w/ partial
+					  * csum */
+#define VIRTIO_NET_F_HOST_SCTP_CSUM   62 /* HOST handles SCTP pkts w/ partial
+					  * csum */
 #define VIRTIO_NET_F_SPEED_DUPLEX 63	/* Device set linkspeed and duplex */
 
 #ifndef VIRTIO_NET_NO_LEGACY
@@ -101,6 +105,7 @@ struct virtio_net_config {
 struct virtio_net_hdr_v1 {
 #define VIRTIO_NET_HDR_F_NEEDS_CSUM	1	/* Use csum_start, csum_offset */
 #define VIRTIO_NET_HDR_F_DATA_VALID	2	/* Csum is valid */
+#define VIRTIO_NET_HDR_F_CSUM_NOT_INET  4       /* Checksum is not inet */
 	__u8 flags;
 #define VIRTIO_NET_HDR_GSO_NONE		0	/* Not a GSO frame */
 #define VIRTIO_NET_HDR_GSO_TCPV4	1	/* GSO frame, IPv4 TCP (TSO) */
-- 
2.9.5

Vladislav Yasevich

2018-May-02 02:07 UTC

head link

[PATCH V2 net-next 2/6] sctp: Handle sctp packets with CHECKSUM_PARTIAL

With SCTP checksum offload available in virtio, it is now
possible for virtio to receive a sctp packet with CHECKSUM_PARTIAL
set (guest-to-guest traffic).  SCTP doesn't really have a
partial checksum like TCP does, because CRC32c can't do partial
additive checksumming.  It's all or nothing.  So an SCTP packet
with CHECKSUM_PARTIAL will have checksum set to 0.  Let SCTP
treat this as a valid checksum if CHECKSUM_PARTIAL is set.

Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
---
 net/sctp/input.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/net/sctp/input.c b/net/sctp/input.c
index ba8a6e6..055b8ffa 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -80,8 +80,17 @@ static inline int sctp_rcv_checksum(struct net *net, struct
sk_buff *skb)
 {
 	struct sctphdr *sh = sctp_hdr(skb);
 	__le32 cmp = sh->checksum;
-	__le32 val = sctp_compute_cksum(skb, 0);
+	__le32 val = 0;
 
+	/* In sctp PARTIAL checksum is always 0.  This is a case of
+	 * a packet received from guest that supports checksum offload.
+	 * Assume it's correct as there is really no way to verify,
+	 * and we want to avaoid computing it unnecesarily.
+	 */
+	if (skb->ip_summed == CHECKSUM_PARTIAL)
+		return 0;
+
+	val = sctp_compute_cksum(skb, 0);
 	if (val != cmp) {
 		/* CRC failure, dump it. */
 		__SCTP_INC_STATS(net, SCTP_MIB_CHECKSUMERRORS);
-- 
2.9.5

Vladislav Yasevich

2018-May-02 02:07 UTC

head link

[PATCH V2 net-next 3/6] sctp: Build sctp offload support into the base kernel

With the SCTP checksum offload support added to virtio, it is
now possible to get into a situation where SCTP not present
in the kernel, but the feature is negotiated.  Handle this just
like we do IPv6 and other modular offloads.
Move the sctp offload out of the sctp module and into the base
kernel.

Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
---
 include/net/sctp/sctp.h | 5 -----
 net/Kconfig             | 1 +
 net/sctp/Kconfig        | 1 -
 net/sctp/Makefile       | 3 ++-
 net/sctp/offload.c      | 4 +++-
 net/sctp/protocol.c     | 3 ---
 6 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index 72c5b8f..625b45f 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -183,11 +183,6 @@ struct sctp_transport *sctp_epaddr_lookup_transport(
 int __net_init sctp_proc_init(struct net *net);
 
 /*
- * sctp/offload.c
- */
-int sctp_offload_init(void);
-
-/*
  * sctp/stream_sched.c
  */
 void sctp_sched_ops_init(void);
diff --git a/net/Kconfig b/net/Kconfig
index 0428f12..2773f98 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -64,6 +64,7 @@ config INET
 	bool "TCP/IP networking"
 	select CRYPTO
 	select CRYPTO_AES
+	select LIBCRC32C
 	---help---
 	  These are the protocols used on the Internet and on most local
 	  Ethernets. It is highly recommended to say Y here (this will enlarge
diff --git a/net/sctp/Kconfig b/net/sctp/Kconfig
index c740b18..d07477a 100644
--- a/net/sctp/Kconfig
+++ b/net/sctp/Kconfig
@@ -9,7 +9,6 @@ menuconfig IP_SCTP
 	select CRYPTO
 	select CRYPTO_HMAC
 	select CRYPTO_SHA1
-	select LIBCRC32C
 	---help---
 	  Stream Control Transmission Protocol
 
diff --git a/net/sctp/Makefile b/net/sctp/Makefile
index e845e45..ee206ca 100644
--- a/net/sctp/Makefile
+++ b/net/sctp/Makefile
@@ -5,6 +5,7 @@
 
 obj-$(CONFIG_IP_SCTP) += sctp.o
 obj-$(CONFIG_INET_SCTP_DIAG) += sctp_diag.o
+obj-$(CONFIG_INET) += offload.o
 
 sctp-y := sm_statetable.o sm_statefuns.o sm_sideeffect.o \
 	  protocol.o endpointola.o associola.o \
@@ -12,7 +13,7 @@ sctp-y := sm_statetable.o sm_statefuns.o sm_sideeffect.o \
 	  inqueue.o outqueue.o ulpqueue.o \
 	  tsnmap.o bind_addr.o socket.o primitive.o \
 	  output.o input.o debug.o stream.o auth.o \
-	  offload.o stream_sched.o stream_sched_prio.o \
+	  stream_sched.o stream_sched_prio.o \
 	  stream_sched_rr.o stream_interleave.o
 
 sctp_diag-y := diag.o
diff --git a/net/sctp/offload.c b/net/sctp/offload.c
index 123e9f2..c61cbde 100644
--- a/net/sctp/offload.c
+++ b/net/sctp/offload.c
@@ -107,7 +107,7 @@ static const struct skb_checksum_ops crc32c_csum_ops = {
 	.combine = sctp_csum_combine,
 };
 
-int __init sctp_offload_init(void)
+static int __init sctp_offload_init(void)
 {
 	int ret;
 
@@ -127,3 +127,5 @@ int __init sctp_offload_init(void)
 out:
 	return ret;
 }
+
+fs_initcall(sctp_offload_init);
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index a24cde2..46d2b63 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -1479,9 +1479,6 @@ static __init int sctp_init(void)
 	if (status)
 		goto err_v6_add_protocol;
 
-	if (sctp_offload_init() < 0)
-		pr_crit("%s: Cannot add SCTP protocol offload\n", __func__);
-
 out:
 	return status;
 err_v6_add_protocol:
-- 
2.9.5

Vladislav Yasevich

2018-May-02 02:07 UTC

head link

[PATCH V2 net-next 4/6] tun: Add support for SCTP checksum offload

Adds a new tun offload flag to allow for SCTP checksum offload.
The flag has to be set by the user and defaults to "no offload".
Add SCTP checksum support to the supported tun features.

Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
---
 drivers/net/tun.c           | 7 ++++++-
 include/uapi/linux/if_tun.h | 1 +
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index a1ba262..4f314a6 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -216,7 +216,7 @@ struct tun_struct {
 	struct net_device	*dev;
 	netdev_features_t	set_features;
 #define TUN_USER_FEATURES (NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
-			  NETIF_F_TSO6)
+			  NETIF_F_TSO6|NETIF_F_SCTP_CRC)
 
 	int			align;
 	int			vnet_hdr_sz;
@@ -2719,6 +2719,11 @@ static int set_offload(struct tun_struct *tun, unsigned
long arg)
 		arg &= ~TUN_F_UFO;
 	}
 
+	if (arg & TUN_F_SCTP_CSUM) {
+		features |= NETIF_F_SCTP_CRC;
+		arg &= ~TUN_F_SCTP_CSUM;
+	}
+
 	/* This gives the user a way to test for new features in future by
 	 * trying to set them. */
 	if (arg)
diff --git a/include/uapi/linux/if_tun.h b/include/uapi/linux/if_tun.h
index ee432cd..061aea8 100644
--- a/include/uapi/linux/if_tun.h
+++ b/include/uapi/linux/if_tun.h
@@ -86,6 +86,7 @@
 #define TUN_F_TSO6	0x04	/* I can handle TSO for IPv6 packets */
 #define TUN_F_TSO_ECN	0x08	/* I can handle TSO with ECN bits. */
 #define TUN_F_UFO	0x10	/* I can handle UFO packets */
+#define TUN_F_SCTP_CSUM 0x20	/* I can handle SCTP checksums offloads */
 
 /* Protocol info prepended to the packets (when IFF_NO_PI is not set) */
 #define TUN_PKT_STRIP	0x0001
-- 
2.9.5

Vladislav Yasevich

2018-May-02 02:07 UTC

head link

[PATCH V2 net-next 5/6] macvlan/macvtap: Add support for SCTP checksum offload.

Since we now have support for software CRC32c offload, turn it on
for macvlan and macvtap devices so that guests can take advantage
of offload SCTP checksums to the host or host hardware.

Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
---
 drivers/net/macvlan.c | 5 +++--
 drivers/net/tap.c     | 8 +++++---
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 725f4b4..646b730 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -834,7 +834,7 @@ static struct lock_class_key macvlan_netdev_addr_lock_key;
 
 #define ALWAYS_ON_OFFLOADS \
 	(NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_GSO_SOFTWARE | \
-	 NETIF_F_GSO_ROBUST | NETIF_F_GSO_ENCAP_ALL)
+	 NETIF_F_GSO_ROBUST | NETIF_F_GSO_ENCAP_ALL | NETIF_F_SCTP_CRC)
 
 #define ALWAYS_ON_FEATURES (ALWAYS_ON_OFFLOADS | NETIF_F_LLTX)
 
@@ -842,7 +842,8 @@ static struct lock_class_key macvlan_netdev_addr_lock_key;
 	(NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_FRAGLIST | \
 	 NETIF_F_GSO | NETIF_F_TSO | NETIF_F_LRO | \
 	 NETIF_F_TSO_ECN | NETIF_F_TSO6 | NETIF_F_GRO | NETIF_F_RXCSUM | \
-	 NETIF_F_HW_VLAN_CTAG_FILTER | NETIF_F_HW_VLAN_STAG_FILTER)
+	 NETIF_F_HW_VLAN_CTAG_FILTER | NETIF_F_HW_VLAN_STAG_FILTER | \
+	 NETIF_F_SCTP_CRC)
 
 #define MACVLAN_STATE_MASK \
 	((1<<__LINK_STATE_NOCARRIER) | (1<<__LINK_STATE_DORMANT))
diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 9b6cb78..2c8512b 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -369,8 +369,7 @@ rx_handler_result_t tap_handle_frame(struct sk_buff **pskb)
 		 *	  check, we either support them all or none.
 		 */
 		if (skb->ip_summed == CHECKSUM_PARTIAL &&
-		    !(features & NETIF_F_CSUM_MASK) &&
-		    skb_checksum_help(skb))
+		    skb_csum_hwoffload_help(skb, features))
 			goto drop;
 		if (ptr_ring_produce(&q->ring, skb))
 			goto drop;
@@ -945,6 +944,9 @@ static int set_offload(struct tap_queue *q, unsigned long
arg)
 		}
 	}
 
+	if (arg & TUN_F_SCTP_CSUM)
+		feature_mask |= NETIF_F_SCTP_CRC;
+
 	/* tun/tap driver inverts the usage for TSO offloads, where
 	 * setting the TSO bit means that the userspace wants to
 	 * accept TSO frames and turning it off means that user space
@@ -1077,7 +1079,7 @@ static long tap_ioctl(struct file *file, unsigned int cmd,
 	case TUNSETOFFLOAD:
 		/* let the user check for future flags */
 		if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
-			    TUN_F_TSO_ECN | TUN_F_UFO))
+			    TUN_F_TSO_ECN | TUN_F_UFO | TUN_F_SCTP_CSUM))
 			return -EINVAL;
 
 		rtnl_lock();
-- 
2.9.5

Vladislav Yasevich

2018-May-02 02:07 UTC

head link

[PATCH V2 net-next 6/6] ipvlan: Add support for SCTP checksum offload

Since ipvlan is a software device, we can turn on SCTP checksum
offload and let the checksum be computed at the lower layer.

Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
---
 drivers/net/ipvlan/ipvlan_main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c
index 450eec2..ddb1590 100644
--- a/drivers/net/ipvlan/ipvlan_main.c
+++ b/drivers/net/ipvlan/ipvlan_main.c
@@ -161,7 +161,8 @@ static void ipvlan_port_destroy(struct net_device *dev)
 	(NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_FRAGLIST | \
 	 NETIF_F_GSO | NETIF_F_TSO | NETIF_F_GSO_ROBUST | \
 	 NETIF_F_TSO_ECN | NETIF_F_TSO6 | NETIF_F_GRO | NETIF_F_RXCSUM | \
-	 NETIF_F_HW_VLAN_CTAG_FILTER | NETIF_F_HW_VLAN_STAG_FILTER)
+	 NETIF_F_HW_VLAN_CTAG_FILTER | NETIF_F_HW_VLAN_STAG_FILTER | \
+	 NETIF_F_SCTP_CRC)
 
 #define IPVLAN_STATE_MASK \
 	((1<<__LINK_STATE_NOCARRIER) | (1<<__LINK_STATE_DORMANT))
-- 
2.9.5

Michael S. Tsirkin

2018-May-02 03:16 UTC

head link

[PATCH V2 net-next 1/6] virtio: Add support for SCTP checksum offloading

On Tue, May 01, 2018 at 10:07:34PM -0400, Vladislav Yasevich
wrote:> To support SCTP checksum offloading, we need to add a new feature
> to virtio_net, so we can negotiate support between the hypervisor
> and the guest.
> The HOST feature bit signifies offloading support for transmit and
> enables device offload features.
> The GUEST feature bit signifies offloading support of recieve and
> is currently only used by the driver in case of xdp.  
> 
> That patch also adds an addition virtio_net header flag which
> mirrors the skb->csum_not_inet flag.  This flags is used to indicate
> that is this an SCTP packet that needs its checksum computed by the
> lower layer.  In this case, the lower layer is the host hypervisor or
> possibly HW nic that supporst CRC32c offload.
> 
> In the case that GUEST feature bit is flag, it will be possible to
> receive a virtio_net header with this bit set, which will set the
> corresponding skb bit.  SCTP protocol will be updated to correctly
> deal with it.
> 
> Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
> ---
>  drivers/net/virtio_net.c        | 14 +++++++++++++-
>  include/linux/virtio_net.h      |  6 ++++++
>  include/uapi/linux/virtio_net.h |  5 +++++
>  3 files changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7b187ec..34af280 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2148,6 +2148,8 @@ static int virtnet_clear_guest_offloads(struct
virtnet_info *vi)
>  
>  	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_CSUM))
>  		offloads = 1ULL << VIRTIO_NET_F_GUEST_CSUM;
> +	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_SCTP_CSUM))
> +		offloads |= 1ULL << VIRTIO_NET_F_GUEST_SCTP_CSUM;
>  
>  	return virtnet_set_guest_offloads(vi, offloads);
>  }
> @@ -2160,6 +2162,8 @@ static int virtnet_restore_guest_offloads(struct
virtnet_info *vi)
>  		return 0;
>  	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_CSUM))
>  		offloads |= 1ULL << VIRTIO_NET_F_GUEST_CSUM;
> +	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_SCTP_CSUM))
> +		offloads |= 1ULL << VIRTIO_NET_F_GUEST_SCTP_CSUM;
>  
>  	return virtnet_set_guest_offloads(vi, offloads);
>  }
> @@ -2724,6 +2728,7 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	/* Do we support "hardware" checksums? */
>  	if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
>  		/* This opens up the world of extra features. */
> +
>  		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG;
>  		if (csum)
>  			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;
> @@ -2746,9 +2751,15 @@ static int virtnet_probe(struct virtio_device *vdev)
>  			dev->features |= dev->hw_features & NETIF_F_ALL_TSO;
>  		/* (!csum && gso) case will be fixed by register_netdev() */
>  	}
> +
>  	if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_CSUM))
>  		dev->features |= NETIF_F_RXCSUM;
>  
> +	if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_SCTP_CSUM)) {
> +		dev->hw_features |= NETIF_F_SCTP_CRC;
> +		dev->features |= NETIF_F_SCTP_CRC;
> +	}
> +
>  	dev->vlan_features = dev->features;
>  
>  	/* MTU range: 68 - 65535 */
> @@ -2962,7 +2973,8 @@ static struct virtio_device_id id_table[] = {
>  	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, \
>  	VIRTIO_NET_F_CTRL_MAC_ADDR, \
>  	VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
> -	VIRTIO_NET_F_SPEED_DUPLEX
> +	VIRTIO_NET_F_SPEED_DUPLEX, \
> +	VIRTIO_NET_F_HOST_SCTP_CSUM, VIRTIO_NET_F_GUEST_SCTP_CSUM
>  
>  static unsigned int features[] = {
>  	VIRTNET_FEATURES,
> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> index f144216..28fffdc 100644
> --- a/include/linux/virtio_net.h
> +++ b/include/linux/virtio_net.h
> @@ -39,6 +39,9 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff
*skb,
>  
>  		if (!skb_partial_csum_set(skb, start, off))
>  			return -EINVAL;
> +
> +		if (hdr->flags & VIRTIO_NET_HDR_F_CSUM_NOT_INET)
> +			skb->csum_not_inet = 1;
>  	}
>  
>  	if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
> @@ -91,6 +94,9 @@ static inline int virtio_net_hdr_from_skb(const struct
sk_buff *skb,
>  				skb_checksum_start_offset(skb));
>  		hdr->csum_offset = __cpu_to_virtio16(little_endian,
>  				skb->csum_offset);
> +
> +		if (skb->csum_not_inet)
> +			hdr->flags |= VIRTIO_NET_HDR_F_CSUM_NOT_INET;
>  	} else if (has_data_valid &&
>  		   skb->ip_summed == CHECKSUM_UNNECESSARY) {
>  		hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
> diff --git a/include/uapi/linux/virtio_net.h
b/include/uapi/linux/virtio_net.h
> index 5de6ed3..9dfca1a 100644
> --- a/include/uapi/linux/virtio_net.h
> +++ b/include/uapi/linux/virtio_net.h
> @@ -57,6 +57,10 @@
>  					 * Steering */
>  #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
>  
> +#define VIRTIO_NET_F_GUEST_SCTP_CSUM  61 /* Guest handles SCTP pks w/
partial
> +					  * csum */
> +#define VIRTIO_NET_F_HOST_SCTP_CSUM   62 /* HOST handles SCTP pkts w/
partial
> +					  * csum */
>  #define VIRTIO_NET_F_SPEED_DUPLEX 63	/* Device set linkspeed and duplex */
>  
>  #ifndef VIRTIO_NET_NO_LEGACY
> @@ -101,6 +105,7 @@ struct virtio_net_config {
>  struct virtio_net_hdr_v1 {
>  #define VIRTIO_NET_HDR_F_NEEDS_CSUM	1	/* Use csum_start, csum_offset */
>  #define VIRTIO_NET_HDR_F_DATA_VALID	2	/* Csum is valid */
> +#define VIRTIO_NET_HDR_F_CSUM_NOT_INET  4       /* Checksum is not inet */
Both comment and name are not very informative.
How about just saying CRC32c ?
>  	__u8 flags;
>  #define VIRTIO_NET_HDR_GSO_NONE		0	/* Not a GSO frame */
>  #define VIRTIO_NET_HDR_GSO_TCPV4	1	/* GSO frame, IPv4 TCP (TSO) */
> -- 
> 2.9.5

Michael S. Tsirkin

2018-May-02 03:24 UTC

head link

[PATCH V2 net-next 5/6] macvlan/macvtap: Add support for SCTP checksum offload.

On Tue, May 01, 2018 at 10:07:38PM -0400, Vladislav Yasevich
wrote:> Since we now have support for software CRC32c offload, turn it on
> for macvlan and macvtap devices so that guests can take advantage
> of offload SCTP checksums to the host or host hardware.
> 
> Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
> ---
>  drivers/net/macvlan.c | 5 +++--
>  drivers/net/tap.c     | 8 +++++---
>  2 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
> index 725f4b4..646b730 100644
> --- a/drivers/net/macvlan.c
> +++ b/drivers/net/macvlan.c
> @@ -834,7 +834,7 @@ static struct lock_class_key
macvlan_netdev_addr_lock_key;
>  
>  #define ALWAYS_ON_OFFLOADS \
>  	(NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_GSO_SOFTWARE | \
> -	 NETIF_F_GSO_ROBUST | NETIF_F_GSO_ENCAP_ALL)
> +	 NETIF_F_GSO_ROBUST | NETIF_F_GSO_ENCAP_ALL | NETIF_F_SCTP_CRC)
>  
>  #define ALWAYS_ON_FEATURES (ALWAYS_ON_OFFLOADS | NETIF_F_LLTX)
>  
> @@ -842,7 +842,8 @@ static struct lock_class_key
macvlan_netdev_addr_lock_key;
>  	(NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_FRAGLIST | \
>  	 NETIF_F_GSO | NETIF_F_TSO | NETIF_F_LRO | \
>  	 NETIF_F_TSO_ECN | NETIF_F_TSO6 | NETIF_F_GRO | NETIF_F_RXCSUM | \
> -	 NETIF_F_HW_VLAN_CTAG_FILTER | NETIF_F_HW_VLAN_STAG_FILTER)
> +	 NETIF_F_HW_VLAN_CTAG_FILTER | NETIF_F_HW_VLAN_STAG_FILTER | \
> +	 NETIF_F_SCTP_CRC)
>  
>  #define MACVLAN_STATE_MASK \
>  	((1<<__LINK_STATE_NOCARRIER) | (1<<__LINK_STATE_DORMANT))
> diff --git a/drivers/net/tap.c b/drivers/net/tap.c
> index 9b6cb78..2c8512b 100644
> --- a/drivers/net/tap.c
> +++ b/drivers/net/tap.c
> @@ -369,8 +369,7 @@ rx_handler_result_t tap_handle_frame(struct sk_buff
**pskb)
>  		 *	  check, we either support them all or none.
>  		 */
>  		if (skb->ip_summed == CHECKSUM_PARTIAL &&
> -		    !(features & NETIF_F_CSUM_MASK) &&
> -		    skb_checksum_help(skb))
> +		    skb_csum_hwoffload_help(skb, features))
>  			goto drop;
>  		if (ptr_ring_produce(&q->ring, skb))
>  			goto drop;
> @@ -945,6 +944,9 @@ static int set_offload(struct tap_queue *q, unsigned
long arg)
>  		}
>  	}
>  
> +	if (arg & TUN_F_SCTP_CSUM)
> +		feature_mask |= NETIF_F_SCTP_CRC;
> +
so this still affects TX, shouldn't this affect RX instead?

>  	/* tun/tap driver inverts the usage for TSO offloads, where
>  	 * setting the TSO bit means that the userspace wants to
>  	 * accept TSO frames and turning it off means that user space
> @@ -1077,7 +1079,7 @@ static long tap_ioctl(struct file *file, unsigned int
cmd,
>  	case TUNSETOFFLOAD:
>  		/* let the user check for future flags */
>  		if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
> -			    TUN_F_TSO_ECN | TUN_F_UFO))
> +			    TUN_F_TSO_ECN | TUN_F_UFO | TUN_F_SCTP_CSUM))
>  			return -EINVAL;
>  
>  		rtnl_lock();
> -- 
> 2.9.5

Michael S. Tsirkin

2018-May-02 14:21 UTC

head link

[PATCH V2 net-next 1/6] virtio: Add support for SCTP checksum offloading

On Wed, May 02, 2018 at 11:14:13AM -0300, Marcelo Ricardo Leitner
wrote:> On Wed, May 02, 2018 at 06:16:45AM +0300, Michael S. Tsirkin wrote:
> > On Tue, May 01, 2018 at 10:07:34PM -0400, Vladislav Yasevich wrote:
> > > To support SCTP checksum offloading, we need to add a new feature
> > > to virtio_net, so we can negotiate support between the hypervisor
> > > and the guest.
> > > The HOST feature bit signifies offloading support for transmit
and
> > > enables device offload features.
> > > The GUEST feature bit signifies offloading support of recieve and
> > > is currently only used by the driver in case of xdp.
> > >
> > > That patch also adds an addition virtio_net header flag which
> > > mirrors the skb->csum_not_inet flag.  This flags is used to
indicate
> > > that is this an SCTP packet that needs its checksum computed by
the
> > > lower layer.  In this case, the lower layer is the host
hypervisor or
> > > possibly HW nic that supporst CRC32c offload.
> > >
> > > In the case that GUEST feature bit is flag, it will be possible
to
> > > receive a virtio_net header with this bit set, which will set the
> > > corresponding skb bit.  SCTP protocol will be updated to
correctly
> > > deal with it.
> > >
> > > Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
> > > ---
> > >  drivers/net/virtio_net.c        | 14 +++++++++++++-
> > >  include/linux/virtio_net.h      |  6 ++++++
> > >  include/uapi/linux/virtio_net.h |  5 +++++
> > >  3 files changed, 24 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > index 7b187ec..34af280 100644
> > > --- a/drivers/net/virtio_net.c
> > > +++ b/drivers/net/virtio_net.c
> > > @@ -2148,6 +2148,8 @@ static int
virtnet_clear_guest_offloads(struct virtnet_info *vi)
> > >
> > >  	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_CSUM))
> > >  		offloads = 1ULL << VIRTIO_NET_F_GUEST_CSUM;
> > > +	if (virtio_has_feature(vi->vdev,
VIRTIO_NET_F_GUEST_SCTP_CSUM))
> > > +		offloads |= 1ULL << VIRTIO_NET_F_GUEST_SCTP_CSUM;
> > >
> > >  	return virtnet_set_guest_offloads(vi, offloads);
> > >  }
> > > @@ -2160,6 +2162,8 @@ static int
virtnet_restore_guest_offloads(struct virtnet_info *vi)
> > >  		return 0;
> > >  	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_CSUM))
> > >  		offloads |= 1ULL << VIRTIO_NET_F_GUEST_CSUM;
> > > +	if (virtio_has_feature(vi->vdev,
VIRTIO_NET_F_GUEST_SCTP_CSUM))
> > > +		offloads |= 1ULL << VIRTIO_NET_F_GUEST_SCTP_CSUM;
> > >
> > >  	return virtnet_set_guest_offloads(vi, offloads);
> > >  }
> > > @@ -2724,6 +2728,7 @@ static int virtnet_probe(struct
virtio_device *vdev)
> > >  	/* Do we support "hardware" checksums? */
> > >  	if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
> > >  		/* This opens up the world of extra features. */
> > > +
> > >  		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG;
> > >  		if (csum)
> > >  			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;
> > > @@ -2746,9 +2751,15 @@ static int virtnet_probe(struct
virtio_device *vdev)
> > >  			dev->features |= dev->hw_features &
NETIF_F_ALL_TSO;
> > >  		/* (!csum && gso) case will be fixed by
register_netdev() */
> > >  	}
> > > +
> > >  	if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_CSUM))
> > >  		dev->features |= NETIF_F_RXCSUM;
> > >
> > > +	if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_SCTP_CSUM)) {
> > > +		dev->hw_features |= NETIF_F_SCTP_CRC;
> > > +		dev->features |= NETIF_F_SCTP_CRC;
> > > +	}
> > > +
> > >  	dev->vlan_features = dev->features;
> > >
> > >  	/* MTU range: 68 - 65535 */
> > > @@ -2962,7 +2973,8 @@ static struct virtio_device_id id_table[] =
{
> > >  	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, \
> > >  	VIRTIO_NET_F_CTRL_MAC_ADDR, \
> > >  	VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
> > > -	VIRTIO_NET_F_SPEED_DUPLEX
> > > +	VIRTIO_NET_F_SPEED_DUPLEX, \
> > > +	VIRTIO_NET_F_HOST_SCTP_CSUM, VIRTIO_NET_F_GUEST_SCTP_CSUM
> > >
> > >  static unsigned int features[] = {
> > >  	VIRTNET_FEATURES,
> > > diff --git a/include/linux/virtio_net.h
b/include/linux/virtio_net.h
> > > index f144216..28fffdc 100644
> > > --- a/include/linux/virtio_net.h
> > > +++ b/include/linux/virtio_net.h
> > > @@ -39,6 +39,9 @@ static inline int virtio_net_hdr_to_skb(struct
sk_buff *skb,
> > >
> > >  		if (!skb_partial_csum_set(skb, start, off))
> > >  			return -EINVAL;
> > > +
> > > +		if (hdr->flags & VIRTIO_NET_HDR_F_CSUM_NOT_INET)
> > > +			skb->csum_not_inet = 1;
> > >  	}
> > >
> > >  	if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
> > > @@ -91,6 +94,9 @@ static inline int virtio_net_hdr_from_skb(const
struct sk_buff *skb,
> > >  				skb_checksum_start_offset(skb));
> > >  		hdr->csum_offset = __cpu_to_virtio16(little_endian,
> > >  				skb->csum_offset);
> > > +
> > > +		if (skb->csum_not_inet)
> > > +			hdr->flags |= VIRTIO_NET_HDR_F_CSUM_NOT_INET;
> > >  	} else if (has_data_valid &&
> > >  		   skb->ip_summed == CHECKSUM_UNNECESSARY) {
> > >  		hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
> > > diff --git a/include/uapi/linux/virtio_net.h
b/include/uapi/linux/virtio_net.h
> > > index 5de6ed3..9dfca1a 100644
> > > --- a/include/uapi/linux/virtio_net.h
> > > +++ b/include/uapi/linux/virtio_net.h
> > > @@ -57,6 +57,10 @@
> > >  					 * Steering */
> > >  #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
> > >
> > > +#define VIRTIO_NET_F_GUEST_SCTP_CSUM  61 /* Guest handles SCTP
pks w/ partial
> > > +					  * csum */
> > > +#define VIRTIO_NET_F_HOST_SCTP_CSUM   62 /* HOST handles SCTP
pkts w/ partial
> > > +					  * csum */
> > >  #define VIRTIO_NET_F_SPEED_DUPLEX 63	/* Device set linkspeed and
duplex */
> > >
> > >  #ifndef VIRTIO_NET_NO_LEGACY
> > > @@ -101,6 +105,7 @@ struct virtio_net_config {
> > >  struct virtio_net_hdr_v1 {
> > >  #define VIRTIO_NET_HDR_F_NEEDS_CSUM	1	/* Use csum_start,
csum_offset */
> > >  #define VIRTIO_NET_HDR_F_DATA_VALID	2	/* Csum is valid */
> > > +#define VIRTIO_NET_HDR_F_CSUM_NOT_INET  4       /* Checksum is
not inet */
> >
> > Both comment and name are not very informative.
> > How about just saying CRC32c ?
> 
> csum_not_inet is following the nomenclature used in sk_buff. Initially
> Davide had named the sk_buff field after crc32c but then it was argued
> that maybe another check method may be introduced later and the name
> would be bogus, thus why the "csum_not_inet".
That's sk_buff internals, since Linux can change these
at any time without breaking anything.

virtio defines an ABI so we won't be able to make it
mean something else, need to document it fully.
"Go read linux net core code" is not a good answer
to the natural question "what does this bit in the
interface do".
> >
> > >  	__u8 flags;
> > >  #define VIRTIO_NET_HDR_GSO_NONE		0	/* Not a GSO frame */
> > >  #define VIRTIO_NET_HDR_GSO_TCPV4	1	/* GSO frame, IPv4 TCP (TSO)
*/
> > > --
> > > 2.9.5
> > --
> > To unsubscribe from this list: send the line "unsubscribe
linux-sctp" in
> > the body of a message to majordomo at vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >

Vlad Yasevich

2018-May-02 17:17 UTC

head link

[PATCH V2 net-next 4/6] tun: Add support for SCTP checksum offload

On 05/02/2018 10:56 AM, Marcelo Ricardo Leitner wrote:> On Wed, May 02, 2018 at 11:53:47AM -0300, Marcelo Ricardo Leitner wrote:
>> On Tue, May 01, 2018 at 10:07:37PM -0400, Vladislav Yasevich wrote:
>>> Adds a new tun offload flag to allow for SCTP checksum offload.
>>> The flag has to be set by the user and defaults to "no
offload".
>>
>> I'm confused here:
>>
>>> +++ b/drivers/net/tun.c
>>> @@ -216,7 +216,7 @@ struct tun_struct {
>>>  	struct net_device	*dev;
>>>  	netdev_features_t	set_features;
>>>  #define TUN_USER_FEATURES
(NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
>>> -			  NETIF_F_TSO6)
>>> +			  NETIF_F_TSO6|NETIF_F_SCTP_CRC)
>>
>> Doesn't adding it here mean it defaults to "offload",
instead?
>>
>> later on, it does:
>>                 dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
>>                                    TUN_USER_FEATURES |
NETIF_F_HW_VLAN_CTAG_TX |
>>                                    NETIF_F_HW_VLAN_STAG_TX;
> 
> Missed to paste the next line too:
>                 dev->features = dev->hw_features | NETIF_F_LLTX;
> 
Yes, as a software device, we can default it to on.  However, qemu will 0-out
the features and then set them up based on the guest (just like regular
checksum).

-vlad

Maybe Matching Threads

Search for more apparently analagous threads

Linux Virtualization - May 2018 - [PATCH V2 net-next 0/6] virtio-net: Add SCTP checksum offload support

[PATCH V2 net-next 0/6] virtio-net: Add SCTP checksum offload support

[PATCH V2 net-next 1/6] virtio: Add support for SCTP checksum offloading

[PATCH V2 net-next 2/6] sctp: Handle sctp packets with CHECKSUM_PARTIAL

[PATCH V2 net-next 3/6] sctp: Build sctp offload support into the base kernel

[PATCH V2 net-next 4/6] tun: Add support for SCTP checksum offload

[PATCH V2 net-next 5/6] macvlan/macvtap: Add support for SCTP checksum offload.

[PATCH V2 net-next 6/6] ipvlan: Add support for SCTP checksum offload

[PATCH V2 net-next 1/6] virtio: Add support for SCTP checksum offloading

[PATCH V2 net-next 5/6] macvlan/macvtap: Add support for SCTP checksum offload.

[PATCH V2 net-next 1/6] virtio: Add support for SCTP checksum offloading

[PATCH V2 net-next 4/6] tun: Add support for SCTP checksum offload

Maybe Matching Threads