octeontx2-pf: mcs: Support VLAN in clear text

Detect whether macsec secy is running on top of VLAN
which implies transmitting VLAN tag in clear text before
macsec SecTag. In this case configure hardware to insert
SecTag after VLAN tag.

Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
Signed-off-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/octeontx2/nic/cn10k_macsec.c

@@ -426,13 +426,16 @@ static int cn10k_mcs_write_tx_secy(struct otx2_nic *pfvf,
 	struct mcs_secy_plcy_write_req *req;
 	struct mbox *mbox = &pfvf->mbox;
 	struct macsec_tx_sc *sw_tx_sc;
-	/* Insert SecTag after 12 bytes (DA+SA)*/
-	u8 tag_offset = 12;
 	u8 sectag_tci = 0;
+	u8 tag_offset;
 	u64 policy;
 	u8 cipher;
 	int ret;
 
+	/* Insert SecTag after 12 bytes (DA+SA) or 16 bytes
+	 * if VLAN tag needs to be sent in clear text.
+	 */
+	tag_offset = txsc->vlan_dev ? 16 : 12;
 	sw_tx_sc = &secy->tx_sc;
 
 	mutex_lock(&mbox->lock);
@@ -1163,6 +1166,7 @@ static int cn10k_mdo_add_secy(struct macsec_context *ctx)
 	txsc->encoding_sa = secy->tx_sc.encoding_sa;
 	txsc->last_validate_frames = secy->validate_frames;
 	txsc->last_replay_protect = secy->replay_protect;
+	txsc->vlan_dev = is_vlan_dev(ctx->netdev);
 
 	list_add(&txsc->entry, &cfg->txsc_list);
 

drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.h

@@ -419,6 +419,7 @@ struct cn10k_mcs_txsc {
 	u8 encoding_sa;
 	u8 salt[CN10K_MCS_SA_PER_SC][MACSEC_SALT_LEN];
 	ssci_t ssci[CN10K_MCS_SA_PER_SC];
+	bool vlan_dev; /* macsec running on VLAN ? */
 };
 
 struct cn10k_mcs_rxsc {