Date: Thu, 24 Aug 2023 12:28:38 +0100
From: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@....com>
To: <netdev@...r.kernel.org>, <linux-net-drivers@....com>
CC: <davem@...emloft.net>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<edumazet@...gle.com>, <ecree.xilinx@...il.com>, <habetsm.xilinx@...il.com>,
	Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@....com>
Subject: [PATCH net-next v2 2/6] sfc: add mac source and destination pedit action offload

Introduce the first pedit set offload functionality for the sfc driver.
In addition to this, add offload functionality for both mac source and
destination pedit set actions.

Co-developed-by: Edward Cree <ecree.xilinx@...il.com>
Signed-off-by: Edward Cree <ecree.xilinx@...il.com>
Signed-off-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@....com>
---
 drivers/net/ethernet/sfc/tc.c | 209 +++++++++++++++++++++++++++++++++-
 1 file changed, 207 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/sfc/tc.c b/drivers/net/ethernet/sfc/tc.c
index 8a9fc2f47514..b9d7c4bb7e69 100644
--- a/drivers/net/ethernet/sfc/tc.c
+++ b/drivers/net/ethernet/sfc/tc.c
@@ -116,7 +116,7 @@ static const struct rhashtable_params efx_tc_recirc_ht_params = {
 	.head_offset	= offsetof(struct efx_tc_recirc_id, linkage),
 };
 
-static struct efx_tc_mac_pedit_action __maybe_unused *efx_tc_flower_get_mac(struct efx_nic *efx,
+static struct efx_tc_mac_pedit_action *efx_tc_flower_get_mac(struct efx_nic *efx,
 							     unsigned char h_addr[ETH_ALEN],
 							     struct netlink_ext_ack *extack)
 {
@@ -155,7 +155,7 @@ static struct efx_tc_mac_pedit_action __maybe_unused *efx_tc_flower_get_mac(stru
 	return ERR_PTR(rc);
 }
 
-static void __maybe_unused efx_tc_flower_put_mac(struct efx_nic *efx,
+static void efx_tc_flower_put_mac(struct efx_nic *efx,
 				  struct efx_tc_mac_pedit_action *ped)
 {
 	if (!refcount_dec_and_test(&ped->ref))
@@ -191,6 +191,10 @@ static void efx_tc_free_action_set(struct efx_nic *efx,
 		list_del(&act->encap_user);
 		efx_tc_flower_release_encap_md(efx, act->encap_md);
 	}
+	if (act->src_mac)
+		efx_tc_flower_put_mac(efx, act->src_mac);
+	if (act->dst_mac)
+		efx_tc_flower_put_mac(efx, act->dst_mac);
 	kfree(act);
 }
 
@@ -753,6 +757,7 @@ static const char *efx_tc_encap_type_name(enum efx_encap_type typ)
 /* For details of action order constraints refer to SF-123102-TC-1§12.6.1 */
 enum efx_tc_action_order {
 	EFX_TC_AO_DECAP,
+	EFX_TC_AO_PEDIT_MAC_ADDRS,
 	EFX_TC_AO_VLAN_POP,
 	EFX_TC_AO_VLAN_PUSH,
 	EFX_TC_AO_COUNT,
@@ -767,6 +772,11 @@ static bool efx_tc_flower_action_order_ok(const struct efx_tc_action_set *act,
 	case EFX_TC_AO_DECAP:
 		if (act->decap)
 			return false;
+		/* PEDIT_MAC_ADDRS must not happen before DECAP, though it
+		 * can wait until much later
+		 */
+		if (act->dst_mac || act->src_mac)
+			return false;
 		fallthrough;
 	case EFX_TC_AO_VLAN_POP:
 		if (act->vlan_pop >= 2)
@@ -786,6 +796,7 @@ static bool efx_tc_flower_action_order_ok(const struct efx_tc_action_set *act,
 		if (act->count)
 			return false;
 		fallthrough;
+	case EFX_TC_AO_PEDIT_MAC_ADDRS:
 	case EFX_TC_AO_ENCAP:
 		if (act->encap_md)
 			return false;
@@ -956,6 +967,191 @@ static void efx_tc_flower_release_lhs_actions(struct efx_nic *efx,
 		efx_tc_flower_put_counter_index(efx, act->count);
 }
 
+/**
+ * struct efx_tc_mangler_state - accumulates 32-bit pedits into fields
+ *
+ * @dst_mac_32:	dst_mac[0:3] has been populated
+ * @dst_mac_16:	dst_mac[4:5] has been populated
+ * @src_mac_16:	src_mac[0:1] has been populated
+ * @src_mac_32:	src_mac[2:5] has been populated
+ * @dst_mac:	h_dest field of ethhdr
+ * @src_mac:	h_source field of ethhdr
+ *
+ * Since FLOW_ACTION_MANGLE comes in 32-bit chunks that do not
+ * necessarily equate to whole fields of the packet header, this
+ * structure is used to hold the cumulative effect of the partial
+ * field pedits that have been processed so far.
+ */
+struct efx_tc_mangler_state {
+	u8 dst_mac_32:1; /* eth->h_dest[0:3] */
+	u8 dst_mac_16:1; /* eth->h_dest[4:5] */
+	u8 src_mac_16:1; /* eth->h_source[0:1] */
+	u8 src_mac_32:1; /* eth->h_source[2:5] */
+	unsigned char dst_mac[ETH_ALEN];
+	unsigned char src_mac[ETH_ALEN];
+};
+
+/** efx_tc_complete_mac_mangle() - pull complete field pedits out of @mung
+ * @efx:	NIC we're installing a flow rule on
+ * @act:	action set (cursor) to update
+ * @mung:	accumulated partial mangles
+ * @extack:	netlink extended ack for reporting errors
+ *
+ * Check @mung to find any combinations of partial mangles that can be
+ * combined into a complete packet field edit, add that edit to @act,
+ * and consume the partial mangles from @mung.
+ */
+
+static int efx_tc_complete_mac_mangle(struct efx_nic *efx,
+				      struct efx_tc_action_set *act,
+				      struct efx_tc_mangler_state *mung,
+				      struct netlink_ext_ack *extack)
+{
+	struct efx_tc_mac_pedit_action *ped;
+
+	if (mung->dst_mac_32 && mung->dst_mac_16) {
+		ped = efx_tc_flower_get_mac(efx, mung->dst_mac, extack);
+		if (IS_ERR(ped))
+			return PTR_ERR(ped);
+
+		/* Check that we have not already populated dst_mac */
+		if (act->dst_mac)
+			efx_tc_flower_put_mac(efx, act->dst_mac);
+
+		act->dst_mac = ped;
+
+		/* consume the incomplete state */
+		mung->dst_mac_32 = 0;
+		mung->dst_mac_16 = 0;
+	}
+	if (mung->src_mac_16 && mung->src_mac_32) {
+		ped = efx_tc_flower_get_mac(efx, mung->src_mac, extack);
+		if (IS_ERR(ped))
+			return PTR_ERR(ped);
+
+		/* Check that we have not already populated src_mac */
+		if (act->src_mac)
+			efx_tc_flower_put_mac(efx, act->src_mac);
+
+		act->src_mac = ped;
+
+		/* consume the incomplete state */
+		mung->src_mac_32 = 0;
+		mung->src_mac_16 = 0;
+	}
+	return 0;
+}
+
+/**
+ * efx_tc_mangle() - handle a single 32-bit (or less) pedit
+ * @efx:	NIC we're installing a flow rule on
+ * @act:	action set (cursor) to update
+ * @fa:		FLOW_ACTION_MANGLE action metadata
+ * @mung:	accumulator for partial mangles
+ * @extack:	netlink extended ack for reporting errors
+ *
+ * Identify the fields written by a FLOW_ACTION_MANGLE, and record
+ * the partial mangle state in @mung.  If this mangle completes an
+ * earlier partial mangle, consume and apply to @act by calling
+ * efx_tc_complete_mac_mangle().
+ */
+
+static int efx_tc_mangle(struct efx_nic *efx, struct efx_tc_action_set *act,
+			 const struct flow_action_entry *fa,
+			 struct efx_tc_mangler_state *mung,
+			 struct netlink_ext_ack *extack)
+{
+	__le32 mac32;
+	__le16 mac16;
+
+	switch (fa->mangle.htype) {
+	case FLOW_ACT_MANGLE_HDR_TYPE_ETH:
+		BUILD_BUG_ON(offsetof(struct ethhdr, h_dest) != 0);
+		BUILD_BUG_ON(offsetof(struct ethhdr, h_source) != 6);
+		if (!efx_tc_flower_action_order_ok(act, EFX_TC_AO_PEDIT_MAC_ADDRS)) {
+			NL_SET_ERR_MSG_MOD(extack,
+					   "Pedit mangle mac action violates action order");
+			return -EOPNOTSUPP;
+		}
+		switch (fa->mangle.offset) {
+		case 0:
+			if (fa->mangle.mask) {
+				NL_SET_ERR_MSG_FMT_MOD(extack,
+						       "Unsupported: mask (%#x) of eth.dst32 mangle",
+						       fa->mangle.mask);
+				return -EOPNOTSUPP;
+			}
+			/* Ethernet address is little-endian */
+			mac32 = cpu_to_le32(fa->mangle.val);
+			memcpy(mung->dst_mac, &mac32, sizeof(mac32));
+			mung->dst_mac_32 = 1;
+			return efx_tc_complete_mac_mangle(efx, act, mung, extack);
+		case 4:
+			if (fa->mangle.mask == 0xffff) {
+				mac16 = cpu_to_le16(fa->mangle.val >> 16);
+				memcpy(mung->src_mac, &mac16, sizeof(mac16));
+				mung->src_mac_16 = 1;
+			} else if (fa->mangle.mask == 0xffff0000) {
+				mac16 = cpu_to_le16((u16)fa->mangle.val);
+				memcpy(mung->dst_mac + 4, &mac16, sizeof(mac16));
+				mung->dst_mac_16 = 1;
+			} else {
+				NL_SET_ERR_MSG_FMT_MOD(extack,
+						       "Unsupported: mask (%#x) of eth+4 mangle is not high or low 16b",
+						       fa->mangle.mask);
+				return -EOPNOTSUPP;
+			}
+			return efx_tc_complete_mac_mangle(efx, act, mung, extack);
+		case 8:
+			if (fa->mangle.mask) {
+				NL_SET_ERR_MSG_FMT_MOD(extack,
+						       "Unsupported: mask (%#x) of eth.src32 mangle",
+						       fa->mangle.mask);
+				return -EOPNOTSUPP;
+			}
+			mac32 = cpu_to_le32(fa->mangle.val);
+			memcpy(mung->src_mac + 2, &mac32, sizeof(mac32));
+			mung->src_mac_32 = 1;
+			return efx_tc_complete_mac_mangle(efx, act, mung, extack);
+		default:
+			NL_SET_ERR_MSG_FMT_MOD(extack, "Unsupported: mangle eth+%u %x/%x",
+					       fa->mangle.offset, fa->mangle.val, fa->mangle.mask);
+			return -EOPNOTSUPP;
+		}
+		break;
+	default:
+		NL_SET_ERR_MSG_FMT_MOD(extack, "Unhandled mangle htype %u for action rule",
+				       fa->mangle.htype);
+		return -EOPNOTSUPP;
+	}
+	return 0;
+}
+
+/**
+ * efx_tc_incomplete_mangle() - check for leftover partial pedits
+ * @mung:	accumulator for partial mangles
+ * @extack:	netlink extended ack for reporting errors
+ *
+ * Since the MAE can only overwrite whole fields, any partial
+ * field mangle left over on reaching packet delivery (mirred or
+ * end of TC actions) cannot be offloaded.  Check for any such
+ * and reject them with -%EOPNOTSUPP.
+ */
+
+static int efx_tc_incomplete_mangle(struct efx_tc_mangler_state *mung,
+				    struct netlink_ext_ack *extack)
+{
+	if (mung->dst_mac_32 || mung->dst_mac_16) {
+		NL_SET_ERR_MSG_MOD(extack, "Incomplete pedit of destination MAC address");
+		return -EOPNOTSUPP;
+	}
+	if (mung->src_mac_16 || mung->src_mac_32) {
+		NL_SET_ERR_MSG_MOD(extack, "Incomplete pedit of source MAC address");
+		return -EOPNOTSUPP;
+	}
+	return 0;
+}
+
 static int efx_tc_flower_replace_foreign(struct efx_nic *efx,
 					 struct net_device *net_dev,
 					 struct flow_cls_offload *tc)
@@ -1351,6 +1547,7 @@ static int efx_tc_flower_replace(struct efx_nic *efx,
 	struct netlink_ext_ack *extack = tc->common.extack;
 	const struct ip_tunnel_info *encap_info = NULL;
 	struct efx_tc_flow_rule *rule = NULL, *old;
+	struct efx_tc_mangler_state mung = {};
 	struct efx_tc_action_set *act = NULL;
 	const struct flow_action_entry *fa;
 	struct efx_rep *from_efv, *to_efv;
@@ -1687,6 +1884,11 @@ static int efx_tc_flower_replace(struct efx_nic *efx,
 			act->vlan_proto[act->vlan_push] = fa->vlan.proto;
 			act->vlan_push++;
 			break;
+		case FLOW_ACTION_MANGLE:
+			rc = efx_tc_mangle(efx, act, fa, &mung, extack);
+			if (rc < 0)
+				goto release;
+			break;
 		case FLOW_ACTION_TUNNEL_ENCAP:
 			if (encap_info) {
 				/* Can't specify encap multiple times.
@@ -1726,6 +1928,9 @@ static int efx_tc_flower_replace(struct efx_nic *efx,
 		}
 	}
 
+	rc = efx_tc_incomplete_mangle(&mung, extack);
+	if (rc < 0)
+		goto release;
 	if (act) {
 		/* Not shot/redirected, so deliver to default dest */
 		if (from_efv == EFX_EFV_PF)
-- 
2.17.1

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