net: intel: introduce {, Intel} Ethernet common library

Not a secret there's a ton of code duplication between two and more Intel
ethernet modules.

Before introducing new changes, which would need to be copied over again,
start decoupling the already existing duplicate functionality into a new
module, which will be shared between several Intel Ethernet drivers.
Add the lookup table which converts 8/10-bit hardware packet type into
a parsed bitfield structure for easy checking packet format parameters,
such as payload level, IP version, etc. This is currently used by i40e,
ice and iavf and it's all the same in all three drivers.
The only difference introduced in this implementation is that instead of
defining a 256 (or 1024 in case of ice) element array, add unlikely()
condition to limit the input to 154 (current maximum non-reserved packet
type). There's no reason to waste 600 (or even 3600) bytes only to not
hurt very unlikely exception packets.
The hash computation function now takes payload level directly as a
pkt_hash_type. There's a couple cases when non-IP ptypes are marked as
L3 payload and in the previous versions their hash level would be 2, not
3. But skb_set_hash() only sees difference between L4 and non-L4, thus
this won't change anything at all.
The module is behind the hidden Kconfig symbol, which the drivers will
select when needed. The exports are behind 'LIBIE' namespace to limit
the scope of the functions.

Not that non-HW-specific symbols will live in yet another module,
libeth. This is done to easily distinguish pretty generic code ready
for reusing by any other vendor and/or for moving the layer up from
the code useful in Intel's 1-100G drivers only.

Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

2 files changed, 158 insertions, 0 deletions

diff --git a/include/linux/net/intel/libie/rx.h b/include/linux/net/intel/libie/rx.h
new file mode 100644
index 00000000000000..37c5c8f26fb94e
--- /dev/null
+++ b/include/linux/net/intel/libie/rx.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright (C) 2024 Intel Corporation */
+
+#ifndef __LIBIE_RX_H
+#define __LIBIE_RX_H
+
+#include <net/libeth/rx.h>
+
+/* O(1) converting i40e/ice/iavf's 8/10-bit hardware packet type to a parsed
+ * bitfield struct.
+ */
+
+#define LIBIE_RX_PT_NUM		154
+
+extern const struct libeth_rx_pt libie_rx_pt_lut[LIBIE_RX_PT_NUM];
+
+/**
+ * libie_rx_pt_parse - convert HW packet type to software bitfield structure
+ * @pt: 10-bit hardware packet type value from the descriptor
+ *
+ * ```libie_rx_pt_lut``` must be accessed only using this wrapper.
+ *
+ * Return: parsed bitfield struct corresponding to the provided ptype.
+ */
+static inline struct libeth_rx_pt libie_rx_pt_parse(u32 pt)
+{
+	if (unlikely(pt >= LIBIE_RX_PT_NUM))
+		pt = 0;
+
+	return libie_rx_pt_lut[pt];
+}
+
+#endif /* __LIBIE_RX_H */
diff --git a/include/net/libeth/rx.h b/include/net/libeth/rx.h
new file mode 100644
index 00000000000000..0807e19f44b3d1
--- /dev/null
+++ b/include/net/libeth/rx.h
@@ -0,0 +1,125 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright (C) 2024 Intel Corporation */
+
+#ifndef __LIBETH_RX_H
+#define __LIBETH_RX_H
+
+#include <net/xdp.h>
+
+/* Converting abstract packet type numbers into a software structure with
+ * the packet parameters to do O(1) lookup on Rx.
+ */
+
+enum {
+	LIBETH_RX_PT_OUTER_L2			= 0U,
+	LIBETH_RX_PT_OUTER_IPV4,
+	LIBETH_RX_PT_OUTER_IPV6,
+};
+
+enum {
+	LIBETH_RX_PT_NOT_FRAG			= 0U,
+	LIBETH_RX_PT_FRAG,
+};
+
+enum {
+	LIBETH_RX_PT_TUNNEL_IP_NONE		= 0U,
+	LIBETH_RX_PT_TUNNEL_IP_IP,
+	LIBETH_RX_PT_TUNNEL_IP_GRENAT,
+	LIBETH_RX_PT_TUNNEL_IP_GRENAT_MAC,
+	LIBETH_RX_PT_TUNNEL_IP_GRENAT_MAC_VLAN,
+};
+
+enum {
+	LIBETH_RX_PT_TUNNEL_END_NONE		= 0U,
+	LIBETH_RX_PT_TUNNEL_END_IPV4,
+	LIBETH_RX_PT_TUNNEL_END_IPV6,
+};
+
+enum {
+	LIBETH_RX_PT_INNER_NONE			= 0U,
+	LIBETH_RX_PT_INNER_UDP,
+	LIBETH_RX_PT_INNER_TCP,
+	LIBETH_RX_PT_INNER_SCTP,
+	LIBETH_RX_PT_INNER_ICMP,
+	LIBETH_RX_PT_INNER_TIMESYNC,
+};
+
+#define LIBETH_RX_PT_PAYLOAD_NONE		PKT_HASH_TYPE_NONE
+#define LIBETH_RX_PT_PAYLOAD_L2			PKT_HASH_TYPE_L2
+#define LIBETH_RX_PT_PAYLOAD_L3			PKT_HASH_TYPE_L3
+#define LIBETH_RX_PT_PAYLOAD_L4			PKT_HASH_TYPE_L4
+
+struct libeth_rx_pt {
+	u32					outer_ip:2;
+	u32					outer_frag:1;
+	u32					tunnel_type:3;
+	u32					tunnel_end_prot:2;
+	u32					tunnel_end_frag:1;
+	u32					inner_prot:3;
+	enum pkt_hash_types			payload_layer:2;
+
+	u32					pad:2;
+	enum xdp_rss_hash_type			hash_type:16;
+};
+
+void libeth_rx_pt_gen_hash_type(struct libeth_rx_pt *pt);
+
+/**
+ * libeth_rx_pt_get_ip_ver - get IP version from a packet type structure
+ * @pt: packet type params
+ *
+ * Wrapper to compile out the IPv6 code from the drivers when not supported
+ * by the kernel.
+ *
+ * Return: @pt.outer_ip or stub for IPv6 when not compiled-in.
+ */
+static inline u32 libeth_rx_pt_get_ip_ver(struct libeth_rx_pt pt)
+{
+#if !IS_ENABLED(CONFIG_IPV6)
+	switch (pt.outer_ip) {
+	case LIBETH_RX_PT_OUTER_IPV4:
+		return LIBETH_RX_PT_OUTER_IPV4;
+	default:
+		return LIBETH_RX_PT_OUTER_L2;
+	}
+#else
+	return pt.outer_ip;
+#endif
+}
+
+/* libeth_has_*() can be used to quickly check whether the HW metadata is
+ * available to avoid further expensive processing such as descriptor reads.
+ * They already check for the corresponding netdev feature to be enabled,
+ * thus can be used as drop-in replacements.
+ */
+
+static inline bool libeth_rx_pt_has_checksum(const struct net_device *dev,
+					     struct libeth_rx_pt pt)
+{
+	/* Non-zero _INNER* is only possible when _OUTER_IPV* is set,
+	 * it is enough to check only for the L4 type.
+	 */
+	return likely(pt.inner_prot > LIBETH_RX_PT_INNER_NONE &&
+		      (dev->features & NETIF_F_RXCSUM));
+}
+
+static inline bool libeth_rx_pt_has_hash(const struct net_device *dev,
+					 struct libeth_rx_pt pt)
+{
+	return likely(pt.payload_layer > LIBETH_RX_PT_PAYLOAD_NONE &&
+		      (dev->features & NETIF_F_RXHASH));
+}
+
+/**
+ * libeth_rx_pt_set_hash - fill in skb hash value basing on the PT
+ * @skb: skb to fill the hash in
+ * @hash: 32-bit hash value from the descriptor
+ * @pt: packet type
+ */
+static inline void libeth_rx_pt_set_hash(struct sk_buff *skb, u32 hash,
+					 struct libeth_rx_pt pt)
+{
+	skb_set_hash(skb, hash, pt.payload_layer);
+}
+
+#endif /* __LIBETH_RX_H */