mlxsw: spectrum_acl: Add Bloom filter handling

Spectrum-2 HW uses Bloom filter in order to skip lookups on specific
eRPs. It uses crc-16-Msbit-first calculation over a specific layout
of a rule's key fields combined with eRP ID as well as region ID.
Per potential lookup, iff the Bloom filter entry of the calculated
index is empty, then the lookup can be skipped. Hence, the mlxsw
driver should update the Bloom filter entry per each rule insertion
or deletion when rules are part of an eRP.

Add functions for adding and deleting entries in the Bloom filter.
In order to do so also add crc-16 computation based on the specific
Spectrum-2 polynomial and a function for encoding the crc-16 input
in the manner dictated by HW implementation.

Signed-off-by: Nir Dotan <nird@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 219 insertions, 0 deletions

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c
index 4685b730e703..505b87846acc 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c
@@ -14,6 +14,213 @@ struct mlxsw_sp_acl_bf {
 	refcount_t refcnt[0];
 };
 
+/* Bloom filter uses a crc-16 hash over chunks of data which contain 4 key
+ * blocks, eRP ID and region ID. In Spectrum-2, region key is combined of up to
+ * 12 key blocks, so there can be up to 3 chunks in the Bloom filter key,
+ * depending on the actual number of key blocks used in the region.
+ * The layout of the Bloom filter key is as follows:
+ *
+ * +-------------------------+------------------------+------------------------+
+ * | Chunk 2 Key blocks 11-8 | Chunk 1 Key blocks 7-4 | Chunk 0 Key blocks 3-0 |
+ * +-------------------------+------------------------+------------------------+
+ */
+#define MLXSW_BLOOM_KEY_CHUNKS 3
+#define MLXSW_BLOOM_KEY_LEN 69
+
+/* Each chunk size is 23 bytes. 18 bytes of it contain 4 key blocks, each is
+ * 36 bits, 2 bytes which hold eRP ID and region ID, and 3 bytes of zero
+ * padding.
+ * The layout of each chunk is as follows:
+ *
+ * +---------+----------------------+-----------------------------------+
+ * | 3 bytes |        2 bytes       |              18 bytes             |
+ * +---------+-----------+----------+-----------------------------------+
+ * | 183:158 |  157:148  | 147:144  |               143:0               |
+ * +---------+-----------+----------+-----------------------------------+
+ * |    0    | region ID |  eRP ID  |      4 Key blocks (18 Bytes)      |
+ * +---------+-----------+----------+-----------------------------------+
+ */
+#define MLXSW_BLOOM_CHUNK_PAD_BYTES 3
+#define MLXSW_BLOOM_CHUNK_KEY_BYTES 18
+#define MLXSW_BLOOM_KEY_CHUNK_BYTES 23
+
+/* The offset of the key block within a chunk is 5 bytes as it comes after
+ * 3 bytes of zero padding and 16 bits of region ID and eRP ID.
+ */
+#define MLXSW_BLOOM_CHUNK_KEY_OFFSET 5
+
+/* Each chunk contains 4 key blocks. Chunk 2 uses key blocks 11-8,
+ * and we need to populate it with 4 key blocks copied from the entry encoded
+ * key. Since the encoded key contains a padding, key block 11 starts at offset
+ * 2. block 7 that is used in chunk 1 starts at offset 20 as 4 key blocks take
+ * 18 bytes.
+ * This array defines key offsets for easy access when copying key blocks from
+ * entry key to Bloom filter chunk.
+ */
+static const u8 chunk_key_offsets[MLXSW_BLOOM_KEY_CHUNKS] = {2, 20, 38};
+
+/* This table is just the CRC of each possible byte. It is
+ * computed, Msbit first, for the Bloom filter polynomial
+ * which is 0x8529 (1 + x^3 + x^5 + x^8 + x^10 + x^15 and
+ * the implicit x^16).
+ */
+static const u16 mlxsw_sp_acl_bf_crc_tab[256] = {
+0x0000, 0x8529, 0x8f7b, 0x0a52, 0x9bdf, 0x1ef6, 0x14a4, 0x918d,
+0xb297, 0x37be, 0x3dec, 0xb8c5, 0x2948, 0xac61, 0xa633, 0x231a,
+0xe007, 0x652e, 0x6f7c, 0xea55, 0x7bd8, 0xfef1, 0xf4a3, 0x718a,
+0x5290, 0xd7b9, 0xddeb, 0x58c2, 0xc94f, 0x4c66, 0x4634, 0xc31d,
+0x4527, 0xc00e, 0xca5c, 0x4f75, 0xdef8, 0x5bd1, 0x5183, 0xd4aa,
+0xf7b0, 0x7299, 0x78cb, 0xfde2, 0x6c6f, 0xe946, 0xe314, 0x663d,
+0xa520, 0x2009, 0x2a5b, 0xaf72, 0x3eff, 0xbbd6, 0xb184, 0x34ad,
+0x17b7, 0x929e, 0x98cc, 0x1de5, 0x8c68, 0x0941, 0x0313, 0x863a,
+0x8a4e, 0x0f67, 0x0535, 0x801c, 0x1191, 0x94b8, 0x9eea, 0x1bc3,
+0x38d9, 0xbdf0, 0xb7a2, 0x328b, 0xa306, 0x262f, 0x2c7d, 0xa954,
+0x6a49, 0xef60, 0xe532, 0x601b, 0xf196, 0x74bf, 0x7eed, 0xfbc4,
+0xd8de, 0x5df7, 0x57a5, 0xd28c, 0x4301, 0xc628, 0xcc7a, 0x4953,
+0xcf69, 0x4a40, 0x4012, 0xc53b, 0x54b6, 0xd19f, 0xdbcd, 0x5ee4,
+0x7dfe, 0xf8d7, 0xf285, 0x77ac, 0xe621, 0x6308, 0x695a, 0xec73,
+0x2f6e, 0xaa47, 0xa015, 0x253c, 0xb4b1, 0x3198, 0x3bca, 0xbee3,
+0x9df9, 0x18d0, 0x1282, 0x97ab, 0x0626, 0x830f, 0x895d, 0x0c74,
+0x91b5, 0x149c, 0x1ece, 0x9be7, 0x0a6a, 0x8f43, 0x8511, 0x0038,
+0x2322, 0xa60b, 0xac59, 0x2970, 0xb8fd, 0x3dd4, 0x3786, 0xb2af,
+0x71b2, 0xf49b, 0xfec9, 0x7be0, 0xea6d, 0x6f44, 0x6516, 0xe03f,
+0xc325, 0x460c, 0x4c5e, 0xc977, 0x58fa, 0xddd3, 0xd781, 0x52a8,
+0xd492, 0x51bb, 0x5be9, 0xdec0, 0x4f4d, 0xca64, 0xc036, 0x451f,
+0x6605, 0xe32c, 0xe97e, 0x6c57, 0xfdda, 0x78f3, 0x72a1, 0xf788,
+0x3495, 0xb1bc, 0xbbee, 0x3ec7, 0xaf4a, 0x2a63, 0x2031, 0xa518,
+0x8602, 0x032b, 0x0979, 0x8c50, 0x1ddd, 0x98f4, 0x92a6, 0x178f,
+0x1bfb, 0x9ed2, 0x9480, 0x11a9, 0x8024, 0x050d, 0x0f5f, 0x8a76,
+0xa96c, 0x2c45, 0x2617, 0xa33e, 0x32b3, 0xb79a, 0xbdc8, 0x38e1,
+0xfbfc, 0x7ed5, 0x7487, 0xf1ae, 0x6023, 0xe50a, 0xef58, 0x6a71,
+0x496b, 0xcc42, 0xc610, 0x4339, 0xd2b4, 0x579d, 0x5dcf, 0xd8e6,
+0x5edc, 0xdbf5, 0xd1a7, 0x548e, 0xc503, 0x402a, 0x4a78, 0xcf51,
+0xec4b, 0x6962, 0x6330, 0xe619, 0x7794, 0xf2bd, 0xf8ef, 0x7dc6,
+0xbedb, 0x3bf2, 0x31a0, 0xb489, 0x2504, 0xa02d, 0xaa7f, 0x2f56,
+0x0c4c, 0x8965, 0x8337, 0x061e, 0x9793, 0x12ba, 0x18e8, 0x9dc1,
+};
+
+static u16 mlxsw_sp_acl_bf_crc_byte(u16 crc, u8 c)
+{
+	return (crc << 8) ^ mlxsw_sp_acl_bf_crc_tab[(crc >> 8) ^ c];
+}
+
+static u16 mlxsw_sp_acl_bf_crc(const u8 *buffer, size_t len)
+{
+	u16 crc = 0;
+
+	while (len--)
+		crc = mlxsw_sp_acl_bf_crc_byte(crc, *buffer++);
+	return crc;
+}
+
+static void
+mlxsw_sp_acl_bf_key_encode(struct mlxsw_sp_acl_atcam_region *aregion,
+			   struct mlxsw_sp_acl_atcam_entry *aentry,
+			   char *output, u8 *len)
+{
+	struct mlxsw_afk_key_info *key_info = aregion->region->key_info;
+	u8 chunk_index, chunk_count, block_count;
+	char *chunk = output;
+	__be16 erp_region_id;
+
+	block_count = mlxsw_afk_key_info_blocks_count_get(key_info);
+	chunk_count = 1 + ((block_count - 1) >> 2);
+	erp_region_id = cpu_to_be16(aentry->ht_key.erp_id |
+				   (aregion->region->id << 4));
+	for (chunk_index = MLXSW_BLOOM_KEY_CHUNKS - chunk_count;
+	     chunk_index < MLXSW_BLOOM_KEY_CHUNKS; chunk_index++) {
+		memset(chunk, 0, MLXSW_BLOOM_CHUNK_PAD_BYTES);
+		memcpy(chunk + MLXSW_BLOOM_CHUNK_PAD_BYTES, &erp_region_id,
+		       sizeof(erp_region_id));
+		memcpy(chunk + MLXSW_BLOOM_CHUNK_KEY_OFFSET,
+		       &aentry->ht_key.enc_key[chunk_key_offsets[chunk_index]],
+		       MLXSW_BLOOM_CHUNK_KEY_BYTES);
+		chunk += MLXSW_BLOOM_KEY_CHUNK_BYTES;
+	}
+	*len = chunk_count * MLXSW_BLOOM_KEY_CHUNK_BYTES;
+}
+
+static unsigned int
+mlxsw_sp_acl_bf_rule_count_index_get(struct mlxsw_sp_acl_bf *bf,
+				     unsigned int erp_bank,
+				     unsigned int bf_index)
+{
+	return erp_bank * bf->bank_size + bf_index;
+}
+
+static unsigned int
+mlxsw_sp_acl_bf_index_get(struct mlxsw_sp_acl_bf *bf,
+			  struct mlxsw_sp_acl_atcam_region *aregion,
+			  struct mlxsw_sp_acl_atcam_entry *aentry)
+{
+	char bf_key[MLXSW_BLOOM_KEY_LEN];
+	u8 bf_size;
+
+	mlxsw_sp_acl_bf_key_encode(aregion, aentry, bf_key, &bf_size);
+	return mlxsw_sp_acl_bf_crc(bf_key, bf_size);
+}
+
+int
+mlxsw_sp_acl_bf_entry_add(struct mlxsw_sp *mlxsw_sp,
+			  struct mlxsw_sp_acl_bf *bf,
+			  struct mlxsw_sp_acl_atcam_region *aregion,
+			  unsigned int erp_bank,
+			  struct mlxsw_sp_acl_atcam_entry *aentry)
+{
+	unsigned int rule_index;
+	char *peabfe_pl;
+	u16 bf_index;
+	int err;
+
+	bf_index = mlxsw_sp_acl_bf_index_get(bf, aregion, aentry);
+	rule_index = mlxsw_sp_acl_bf_rule_count_index_get(bf, erp_bank,
+							  bf_index);
+
+	if (refcount_inc_not_zero(&bf->refcnt[rule_index]))
+		return 0;
+
+	peabfe_pl = kmalloc(MLXSW_REG_PEABFE_LEN, GFP_KERNEL);
+	if (!peabfe_pl)
+		return -ENOMEM;
+
+	mlxsw_reg_peabfe_pack(peabfe_pl);
+	mlxsw_reg_peabfe_rec_pack(peabfe_pl, 0, 1, erp_bank, bf_index);
+	err = mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(peabfe), peabfe_pl);
+	kfree(peabfe_pl);
+	if (err)
+		return err;
+
+	refcount_set(&bf->refcnt[rule_index], 1);
+	return 0;
+}
+
+void
+mlxsw_sp_acl_bf_entry_del(struct mlxsw_sp *mlxsw_sp,
+			  struct mlxsw_sp_acl_bf *bf,
+			  struct mlxsw_sp_acl_atcam_region *aregion,
+			  unsigned int erp_bank,
+			  struct mlxsw_sp_acl_atcam_entry *aentry)
+{
+	unsigned int rule_index;
+	char *peabfe_pl;
+	u16 bf_index;
+
+	bf_index = mlxsw_sp_acl_bf_index_get(bf, aregion, aentry);
+	rule_index = mlxsw_sp_acl_bf_rule_count_index_get(bf, erp_bank,
+							  bf_index);
+
+	if (refcount_dec_and_test(&bf->refcnt[rule_index])) {
+		peabfe_pl = kmalloc(MLXSW_REG_PEABFE_LEN, GFP_KERNEL);
+		if (!peabfe_pl)
+			return;
+
+		mlxsw_reg_peabfe_pack(peabfe_pl);
+		mlxsw_reg_peabfe_rec_pack(peabfe_pl, 0, 0, erp_bank, bf_index);
+		mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(peabfe), peabfe_pl);
+		kfree(peabfe_pl);
+	}
+}
+
 struct mlxsw_sp_acl_bf *
 mlxsw_sp_acl_bf_init(struct mlxsw_sp *mlxsw_sp, unsigned int num_erp_banks)
 {
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.h b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.h
index c65c902cb56a..30ac4d0132de 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.h
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.h
@@ -260,6 +260,18 @@ void mlxsw_sp_acl_erps_fini(struct mlxsw_sp *mlxsw_sp,
 
 struct mlxsw_sp_acl_bf;
 
+int
+mlxsw_sp_acl_bf_entry_add(struct mlxsw_sp *mlxsw_sp,
+			  struct mlxsw_sp_acl_bf *bf,
+			  struct mlxsw_sp_acl_atcam_region *aregion,
+			  unsigned int erp_bank,
+			  struct mlxsw_sp_acl_atcam_entry *aentry);
+void
+mlxsw_sp_acl_bf_entry_del(struct mlxsw_sp *mlxsw_sp,
+			  struct mlxsw_sp_acl_bf *bf,
+			  struct mlxsw_sp_acl_atcam_region *aregion,
+			  unsigned int erp_bank,
+			  struct mlxsw_sp_acl_atcam_entry *aentry);
 struct mlxsw_sp_acl_bf *
 mlxsw_sp_acl_bf_init(struct mlxsw_sp *mlxsw_sp, unsigned int num_erp_banks);
 void mlxsw_sp_acl_bf_fini(struct mlxsw_sp_acl_bf *bf);