Merge branch 'udp_tunnel-add-NIC-RX-port-offload-infrastructure'

Jakub Kicinski says:

====================
udp_tunnel: add NIC RX port offload infrastructure

Kernel has a facility to notify drivers about the UDP tunnel ports
so that devices can recognize tunneled packets. This is important
mostly for RX - devices which don't support CHECKSUM_COMPLETE can
report checksums of inner packets, and compute RSS over inner headers.
Some drivers also match the UDP tunnel ports also for TX, although
doing so may lead to false positives and negatives.

Unfortunately the user experience when trying to take adavantage
of these facilities is suboptimal. First of all there is no way
for users to check which ports are offloaded. Many drivers resort
to printing messages to aid debugging, other use debugfs. Even worse
the availability of the RX features (NETIF_F_RX_UDP_TUNNEL_PORT)
is established purely on the basis of the driver having the ndos
installed. For most drivers, however, the ability to perform offloads
is contingent on device capabilities (driver support multiple device
and firmware versions). Unless driver resorts to hackish clearing
of features set incorrectly by the core - users are left guessing
whether their device really supports UDP tunnel port offload or not.

There is currently no way to indicate or configure whether RX
features include just the checksum offload or checksum and using
inner headers for RSS. Many drivers default to not using inner
headers for RSS because most implementations populate the source
port with entropy from the inner headers. This, however, is not
always the case, for example certain switches are only able to
use a fixed source port during encapsulation.

We have also seen many driver authors get the intricacies of UDP
tunnel port offloads wrong. Most commonly the drivers forget to
perform reference counting, or take sleeping locks in the callbacks.

This work tries to improve the situation by pulling the UDP tunnel
port table maintenance out of the drivers. It turns out that almost
all drivers maintain a fixed size table of ports (in most cases one
per tunnel type), so we can take care of all the refcounting in the
core, and let the driver specify if they need to sleep in the
callbacks or not. The new common implementation will also support
replacing ports - when a port is removed from a full table it will
try to find a previously missing port to take its place.

This patch only implements the core functionality along with a few
drivers I was hoping to test manually [1] along with a test based
on a netdevsim implementation. Following patches will convert all
the drivers. Once that's complete we can remove the ndos, and rely
directly on the new infrastrucutre.

Then after RSS (RXFH) is converted to netlink we can add the ability
to configure the use of inner RSS headers for UDP tunnels.

[1] Unfortunately I wasn't able to, turns out 2 of the devices
I had access to were older generation or had old FW, and they
did not actually support UDP tunnel port notifications (see
the second paragraph). The thrid device appears to program
the UDP ports correctly but it generates bad UDP checksums with
or without these patches. Long story short - I'd appreciate
reviews and testing here..

v4:
 - better build fix (hopefully this one does it..)
v3:
 - fix build issue;
 - improve bnxt changes.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
index 4ded54a21e1e..d164052e0393 100644
--- a/drivers/net/netdevsim/netdevsim.h
+++ b/drivers/net/netdevsim/netdevsim.h
@@ -13,6 +13,7 @@
  * THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
  */
 
+#include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
@@ -29,6 +30,7 @@
 
 #define NSIM_IPSEC_MAX_SA_COUNT		33
 #define NSIM_IPSEC_VALID		BIT(31)
+#define NSIM_UDP_TUNNEL_N_PORTS		4
 
 struct nsim_sa {
 	struct xfrm_state *xs;
@@ -72,12 +74,23 @@ struct netdevsim {
 
 	bool bpf_map_accept;
 	struct nsim_ipsec ipsec;
+	struct {
+		u32 inject_error;
+		u32 sleep;
+		u32 ports[2][NSIM_UDP_TUNNEL_N_PORTS];
+		struct debugfs_u32_array dfs_ports[2];
+	} udp_ports;
 };
 
 struct netdevsim *
 nsim_create(struct nsim_dev *nsim_dev, struct nsim_dev_port *nsim_dev_port);
 void nsim_destroy(struct netdevsim *ns);
 
+void nsim_udp_tunnels_debugfs_create(struct nsim_dev *nsim_dev);
+int nsim_udp_tunnels_info_create(struct nsim_dev *nsim_dev,
+				 struct net_device *dev);
+void nsim_udp_tunnels_info_destroy(struct net_device *dev);
+
 #ifdef CONFIG_BPF_SYSCALL
 int nsim_bpf_dev_init(struct nsim_dev *nsim_dev);
 void nsim_bpf_dev_exit(struct nsim_dev *nsim_dev);
@@ -183,6 +196,12 @@ struct nsim_dev {
 	bool fail_trap_group_set;
 	bool fail_trap_policer_set;
 	bool fail_trap_policer_counter_get;
+	struct {
+		bool sync_all;
+		bool open_only;
+		bool ipv4_only;
+		u32 sleep;
+	} udp_ports;
 };
 
 static inline struct net *nsim_dev_net(struct nsim_dev *nsim_dev)