sfc: bare bones TC offload on EF100

This is the absolute minimum viable TC implementation to get traffic to
 VFs and allow them to be tested; it supports no match fields besides
 ingress port, no actions besides mirred and drop, and no stats.
Example usage:
    tc filter add dev $PF parent ffff: flower skip_sw \
        action mirred egress mirror dev $VFREP
    tc filter add dev $VFREP parent ffff: flower skip_sw \
        action mirred egress redirect dev $PF
 gives a VF unfiltered access to the network out the physical port ($PF
 acts here as a physical port representor).
More matches, actions, and counters will be added in subsequent patches.

Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sfc/mae.c

@@ -168,6 +168,111 @@ int efx_mae_get_caps(struct efx_nic *efx, struct mae_caps *caps)
 				       caps->action_rule_fields);
 }
 
+/* Bit twiddling:
+ * Prefix: 1...110...0
+ *      ~: 0...001...1
+ *    + 1: 0...010...0 is power of two
+ * so (~x) & ((~x) + 1) == 0.  Converse holds also.
+ */
+#define is_prefix_byte(_x)	!(((_x) ^ 0xff) & (((_x) ^ 0xff) + 1))
+
+enum mask_type { MASK_ONES, MASK_ZEROES, MASK_PREFIX, MASK_OTHER };
+
+static const char *mask_type_name(enum mask_type typ)
+{
+	switch (typ) {
+	case MASK_ONES:
+		return "all-1s";
+	case MASK_ZEROES:
+		return "all-0s";
+	case MASK_PREFIX:
+		return "prefix";
+	case MASK_OTHER:
+		return "arbitrary";
+	default: /* can't happen */
+		return "unknown";
+	}
+}
+
+/* Checks a (big-endian) bytestring is a bit prefix */
+static enum mask_type classify_mask(const u8 *mask, size_t len)
+{
+	bool zeroes = true; /* All bits seen so far are zeroes */
+	bool ones = true; /* All bits seen so far are ones */
+	bool prefix = true; /* Valid prefix so far */
+	size_t i;
+
+	for (i = 0; i < len; i++) {
+		if (ones) {
+			if (!is_prefix_byte(mask[i]))
+				prefix = false;
+		} else if (mask[i]) {
+			prefix = false;
+		}
+		if (mask[i] != 0xff)
+			ones = false;
+		if (mask[i])
+			zeroes = false;
+	}
+	if (ones)
+		return MASK_ONES;
+	if (zeroes)
+		return MASK_ZEROES;
+	if (prefix)
+		return MASK_PREFIX;
+	return MASK_OTHER;
+}
+
+static int efx_mae_match_check_cap_typ(u8 support, enum mask_type typ)
+{
+	switch (support) {
+	case MAE_FIELD_UNSUPPORTED:
+	case MAE_FIELD_SUPPORTED_MATCH_NEVER:
+		if (typ == MASK_ZEROES)
+			return 0;
+		return -EOPNOTSUPP;
+	case MAE_FIELD_SUPPORTED_MATCH_OPTIONAL:
+		if (typ == MASK_ZEROES)
+			return 0;
+		fallthrough;
+	case MAE_FIELD_SUPPORTED_MATCH_ALWAYS:
+		if (typ == MASK_ONES)
+			return 0;
+		return -EINVAL;
+	case MAE_FIELD_SUPPORTED_MATCH_PREFIX:
+		if (typ == MASK_OTHER)
+			return -EOPNOTSUPP;
+		return 0;
+	case MAE_FIELD_SUPPORTED_MATCH_MASK:
+		return 0;
+	default:
+		return -EIO;
+	}
+}
+
+int efx_mae_match_check_caps(struct efx_nic *efx,
+			     const struct efx_tc_match_fields *mask,
+			     struct netlink_ext_ack *extack)
+{
+	const u8 *supported_fields = efx->tc->caps->action_rule_fields;
+	__be32 ingress_port = cpu_to_be32(mask->ingress_port);
+	enum mask_type ingress_port_mask_type;
+	int rc;
+
+	/* Check for _PREFIX assumes big-endian, so we need to convert */
+	ingress_port_mask_type = classify_mask((const u8 *)&ingress_port,
+					       sizeof(ingress_port));
+	rc = efx_mae_match_check_cap_typ(supported_fields[MAE_FIELD_INGRESS_PORT],
+					 ingress_port_mask_type);
+	if (rc) {
+		efx_tc_err(efx, "No support for %s mask in field ingress_port\n",
+			   mask_type_name(ingress_port_mask_type));
+		NL_SET_ERR_MSG_MOD(extack, "Unsupported mask type for ingress_port");
+		return rc;
+	}
+	return 0;
+}
+
 static bool efx_mae_asl_id(u32 id)
 {
 	return !!(id & BIT(31));
@@ -335,6 +440,10 @@ static int efx_mae_populate_match_criteria(MCDI_DECLARE_STRUCT_PTR(match_crit),
 	}
 	MCDI_STRUCT_SET_DWORD(match_crit, MAE_FIELD_MASK_VALUE_PAIRS_V2_INGRESS_MPORT_SELECTOR_MASK,
 			      match->mask.ingress_port);
+	MCDI_STRUCT_SET_BYTE(match_crit, MAE_FIELD_MASK_VALUE_PAIRS_V2_RECIRC_ID,
+			     match->value.recirc_id);
+	MCDI_STRUCT_SET_BYTE(match_crit, MAE_FIELD_MASK_VALUE_PAIRS_V2_RECIRC_ID_MASK,
+			     match->mask.recirc_id);
 	return 0;
 }
 

drivers/net/ethernet/sfc/mae.h

@@ -37,6 +37,10 @@ struct mae_caps {
 
 int efx_mae_get_caps(struct efx_nic *efx, struct mae_caps *caps);
 
+int efx_mae_match_check_caps(struct efx_nic *efx,
+			     const struct efx_tc_match_fields *mask,
+			     struct netlink_ext_ack *extack);
+
 int efx_mae_alloc_action_set(struct efx_nic *efx, struct efx_tc_action_set *act);
 int efx_mae_free_action_set(struct efx_nic *efx, u32 fw_id);
 

drivers/net/ethernet/sfc/mcdi.h

@@ -201,13 +201,23 @@ void efx_mcdi_sensor_event(struct efx_nic *efx, efx_qword_t *ev);
 	((u8 *)(_buf) + (_offset))
 #define MCDI_PTR(_buf, _field)						\
 	_MCDI_PTR(_buf, MC_CMD_ ## _field ## _OFST)
+/* Use MCDI_STRUCT_ functions to access members of MCDI structuredefs.
+ * _buf should point to the start of the structure, typically obtained with
+ * MCDI_DECLARE_STRUCT_PTR(structure) = _MCDI_DWORD(mcdi_buf, FIELD_WHICH_IS_STRUCT);
+ */
+#define MCDI_STRUCT_PTR(_buf, _field)					\
+	_MCDI_PTR(_buf, _field ## _OFST)
 #define _MCDI_CHECK_ALIGN(_ofst, _align)				\
 	((_ofst) + BUILD_BUG_ON_ZERO((_ofst) & (_align - 1)))
 #define _MCDI_DWORD(_buf, _field)					\
 	((_buf) + (_MCDI_CHECK_ALIGN(MC_CMD_ ## _field ## _OFST, 4) >> 2))
 #define _MCDI_STRUCT_DWORD(_buf, _field)				\
 	((_buf) + (_MCDI_CHECK_ALIGN(_field ## _OFST, 4) >> 2))
 
+#define MCDI_STRUCT_SET_BYTE(_buf, _field, _value) do {			\
+	BUILD_BUG_ON(_field ## _LEN != 1);				\
+	*(u8 *)MCDI_STRUCT_PTR(_buf, _field) = _value;			\
+	} while (0)
 #define MCDI_BYTE(_buf, _field)						\
 	((void)BUILD_BUG_ON_ZERO(MC_CMD_ ## _field ## _LEN != 1),	\
 	 *MCDI_PTR(_buf, _field))