From 62fafcd63139920eb25b3fbf154177ce3e6f3232 Mon Sep 17 00:00:00 2001
From: Xin Long <lucien.xin@gmail.com>
Date: Thu, 28 Jan 2021 17:18:31 +0800
Subject: [PATCH 1/2] net: support ip generic csum processing in
skb_csum_hwoffload_help
NETIF_F_IP|IPV6_CSUM feature flag indicates UDP and TCP csum offload
while NETIF_F_HW_CSUM feature flag indicates ip generic csum offload
for HW, which includes not only for TCP/UDP csum, but also for other
protocols' csum like GRE's.
However, in skb_csum_hwoffload_help() it only checks features against
NETIF_F_CSUM_MASK(NETIF_F_HW|IP|IPV6_CSUM). So if it's a non TCP/UDP
packet and the features doesn't support NETIF_F_HW_CSUM, but supports
NETIF_F_IP|IPV6_CSUM only, it would still return 0 and leave the HW
to do csum.
This patch is to support ip generic csum processing by checking
NETIF_F_HW_CSUM for all protocols, and check (NETIF_F_IP_CSUM |
NETIF_F_IPV6_CSUM) only for TCP and UDP.
Note that we're using skb->csum_offset to check if it's a TCP/UDP
proctol, this might be fragile. However, as Alex said, for now we
only have a few L4 protocols that are requesting Tx csum offload,
we'd better fix this until a new protocol comes with a same csum
offset.
v1->v2:
- not extend skb->csum_not_inet, but use skb->csum_offset to tell
if it's an UDP/TCP csum packet.
v2->v3:
- add a note in the changelog, as Willem suggested.
Suggested-by: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
net/core/dev.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 6df3f1bcdc68..aae116d059da 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3621,7 +3621,18 @@ int skb_csum_hwoffload_help(struct sk_buff *skb,
return !!(features & NETIF_F_SCTP_CRC) ? 0 :
skb_crc32c_csum_help(skb);
- return !!(features & NETIF_F_CSUM_MASK) ? 0 : skb_checksum_help(skb);
+ if (features & NETIF_F_HW_CSUM)
+ return 0;
+
+ if (features & (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM)) {
+ switch (skb->csum_offset) {
+ case offsetof(struct tcphdr, check):
+ case offsetof(struct udphdr, check):
+ return 0;
+ }
+ }
+
+ return skb_checksum_help(skb);
}
EXPORT_SYMBOL(skb_csum_hwoffload_help);
From efa1a65c7e1946ff174c56d36bf015ff9e11c4a1 Mon Sep 17 00:00:00 2001
From: Xin Long <lucien.xin@gmail.com>
Date: Thu, 28 Jan 2021 17:18:32 +0800
Subject: [PATCH 2/2] ip_gre: add csum offload support for gre header
This patch is to add csum offload support for gre header:
On the TX path in gre_build_header(), when CHECKSUM_PARTIAL's set
for inner proto, it will calculate the csum for outer proto, and
inner csum will be offloaded later. Otherwise, CHECKSUM_PARTIAL
and csum_start/offset will be set for outer proto, and the outer
csum will be offloaded later.
On the GSO path in gre_gso_segment(), when CHECKSUM_PARTIAL is
not set for inner proto and the hardware supports csum offload,
CHECKSUM_PARTIAL and csum_start/offset will be set for outer
proto, and outer csum will be offloaded later. Otherwise, it
will do csum for outer proto by calling gso_make_checksum().
Note that SCTP has to do the csum by itself for non GSO path in
sctp_packet_pack(), as gre_build_header() can't handle the csum
with CHECKSUM_PARTIAL set for SCTP CRC csum offload.
v1->v2:
- remove the SCTP part, as GRE dev doesn't support SCTP CRC CSUM
and it will always do checksum for SCTP in sctp_packet_pack()
when it's not a GSO packet.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
include/net/gre.h | 19 +++++++------------
net/ipv4/gre_offload.c | 15 +++++++++++++--
2 files changed, 20 insertions(+), 14 deletions(-)
diff --git a/include/net/gre.h b/include/net/gre.h
index b60f212c16c6..4e209708b754 100644
--- a/include/net/gre.h
+++ b/include/net/gre.h
@@ -106,17 +106,6 @@ static inline __be16 gre_tnl_flags_to_gre_flags(__be16 tflags)
return flags;
}
-static inline __sum16 gre_checksum(struct sk_buff *skb)
-{
- __wsum csum;
-
- if (skb->ip_summed == CHECKSUM_PARTIAL)
- csum = lco_csum(skb);
- else
- csum = skb_checksum(skb, 0, skb->len, 0);
- return csum_fold(csum);
-}
-
static inline void gre_build_header(struct sk_buff *skb, int hdr_len,
__be16 flags, __be16 proto,
__be32 key, __be32 seq)
@@ -146,7 +135,13 @@ static inline void gre_build_header(struct sk_buff *skb, int hdr_len,
!(skb_shinfo(skb)->gso_type &
(SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) {
*ptr = 0;
- *(__sum16 *)ptr = gre_checksum(skb);
+ if (skb->ip_summed == CHECKSUM_PARTIAL) {
+ *(__sum16 *)ptr = csum_fold(lco_csum(skb));
+ } else {
+ skb->ip_summed = CHECKSUM_PARTIAL;
+ skb->csum_start = skb_transport_header(skb) - skb->head;
+ skb->csum_offset = sizeof(*greh);
+ }
}
}
}
diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
index 10bc49bde9a1..1121a9d5fed9 100644
--- a/net/ipv4/gre_offload.c
+++ b/net/ipv4/gre_offload.c
@@ -15,10 +15,10 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
+ bool need_csum, offload_csum, gso_partial, need_ipsec;
struct sk_buff *segs = ERR_PTR(-EINVAL);
u16 mac_offset = skb->mac_header;
__be16 protocol = skb->protocol;
- bool need_csum, gso_partial;
u16 mac_len = skb->mac_len;
int gre_offset, outer_hlen;
@@ -47,6 +47,11 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
if (need_csum)
features &= ~NETIF_F_SCTP_CRC;
+ need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb));
+ /* Try to offload checksum if possible */
+ offload_csum = !!(need_csum && !need_ipsec &&
+ (skb->dev->features & NETIF_F_HW_CSUM));
+
/* segment inner packet. */
segs = skb_mac_gso_segment(skb, features);
if (IS_ERR_OR_NULL(segs)) {
@@ -100,7 +105,13 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
}
*(pcsum + 1) = 0;
- *pcsum = gso_make_checksum(skb, 0);
+ if (skb->encapsulation || !offload_csum) {
+ *pcsum = gso_make_checksum(skb, 0);
+ } else {
+ skb->ip_summed = CHECKSUM_PARTIAL;
+ skb->csum_start = skb_transport_header(skb) - skb->head;
+ skb->csum_offset = sizeof(*greh);
+ }
} while ((skb = skb->next));
out:
return segs;