netdev - [PATCH net-next 1/5] virtio: Add support for SCTP checksum offloading

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Message-Id: <20180402134006.10111-2-vyasevic@redhat.com>
Date:   Mon,  2 Apr 2018 09:40:02 -0400
From:   Vladislav Yasevich <vyasevich@...il.com>
To:     netdev@...r.kernel.org
Cc:     linux-sctp@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, mst@...hat.com,
        jasowang@...hat.com, nhorman@...driver.com,
        Vladislav Yasevich <vyasevic@...hat.com>
Subject: [PATCH net-next 1/5] 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 signalling to the guest that an alternate checksum needs to
be used is done via a new flag in the virtio_net_hdr.  If the
flag is set, the host will know to perform an alternate checksum
calculation, which right now is only CRC32c.

Signed-off-by: Vladislav Yasevich <vyasevic@...hat.com>
---
 drivers/net/virtio_net.c        | 11 ++++++++---
 include/linux/virtio_net.h      |  6 ++++++
 include/uapi/linux/virtio_net.h |  2 ++
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 7b187ec..b601294 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2724,9 +2724,14 @@ 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;
+		netdev_features_t sctp = 0;
+
+		if (virtio_has_feature(vdev, VIRTIO_NET_F_SCTP_CSUM))
+			sctp |= NETIF_F_SCTP_CRC;
+
+		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG | sctp;
 		if (csum)
-			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;
+			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG | sctp;
 
 		if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
 			dev->hw_features |= NETIF_F_TSO
@@ -2952,7 +2957,7 @@ static struct virtio_device_id id_table[] = {
 };
 
 #define VIRTNET_FEATURES \
-	VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM, \
+	VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM,  VIRTIO_NET_F_SCTP_CSUM, \
 	VIRTIO_NET_F_MAC, \
 	VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6, \
 	VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6, \
diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index f144216..2e7a64a 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) {
@@ -96,6 +99,9 @@ static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
 		hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
 	} /* else everything is zero */
 
+	if (skb->csum_not_inet)
+		hdr->flags &= VIRTIO_NET_HDR_F_CSUM_NOT_INET;
+
 	return 0;
 }
 
diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
index 5de6ed3..3f279c8 100644
--- a/include/uapi/linux/virtio_net.h
+++ b/include/uapi/linux/virtio_net.h
@@ -36,6 +36,7 @@
 #define VIRTIO_NET_F_GUEST_CSUM	1	/* Guest handles pkts w/ partial csum */
 #define VIRTIO_NET_F_CTRL_GUEST_OFFLOADS 2 /* Dynamic offload configuration. */
 #define VIRTIO_NET_F_MTU	3	/* Initial MTU advice */
+#define VIRTIO_NET_F_SCTP_CSUM  4	/* SCTP checksum offload support */
 #define VIRTIO_NET_F_MAC	5	/* Host has given MAC address. */
 #define VIRTIO_NET_F_GUEST_TSO4	7	/* Guest can handle TSOv4 in. */
 #define VIRTIO_NET_F_GUEST_TSO6	8	/* Guest can handle TSOv6 in. */
@@ -101,6 +102,7 @@ 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