net/smc: support SMCv2.x supplemental features negotiation

This patch adds SMCv2.x supplemental features negotiation. Supported
SMCv2.x supplemental features are represented by feature_mask in FCE
field. The negotiation process is as follows.

 Server                                        Client
            Proposal(features(c-mask bits))
      <-----------------------------------------
            Accept(features(s-mask bits))
      ----------------------------------------->
           Confirm(features(s&c-mask bits))
      <-----------------------------------------
Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Reviewed-and-tested-by: Wenjia Zhang <wenjia@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/smc/smc.h

@@ -58,6 +58,10 @@ enum smc_state {		/* possible states of an SMC socket */
 	SMC_PROCESSABORT	= 27,
 };
 
+#define SMC_FEATURE_MASK	0	/* bitmask of
+					 * supported supplemental features
+					 */
+
 struct smc_link_group;
 
 struct smc_wr_rx_hdr {	/* common prefix part of LLC and CDC to demultiplex */

net/smc/smc_clc.c

@@ -438,6 +438,7 @@ static int smc_clc_fill_fce_v2x(struct smc_clc_first_contact_ext_v2x *fce_v2x,
 			fce_v2x->max_conns = ini->max_conns;
 			fce_v2x->max_links = ini->max_links;
 		}
+		fce_v2x->feature_mask = htons(ini->feature_mask);
 	}
 
 out:
@@ -907,6 +908,7 @@ int smc_clc_send_proposal(struct smc_sock *smc, struct smc_init_info *ini)
 		pclc_smcd->v2_ext_offset = htons(v2_ext_offset);
 		plen += sizeof(*v2_ext);
 
+		v2_ext->feature_mask = htons(SMC_FEATURE_MASK);
 		read_lock(&smc_clc_eid_table.lock);
 		v2_ext->hdr.eid_cnt = smc_clc_eid_table.ueid_cnt;
 		plen += smc_clc_eid_table.ueid_cnt * SMC_MAX_EID_LEN;
@@ -1208,6 +1210,7 @@ int smc_clc_srv_v2x_features_validate(struct smc_sock *smc,
 
 	ini->max_conns = SMC_CONN_PER_LGR_MAX;
 	ini->max_links = SMC_LINKS_ADD_LNK_MAX;
+	ini->feature_mask = SMC_FEATURE_MASK;
 
 	if ((!(ini->smcd_version & SMC_V2) && !(ini->smcr_version & SMC_V2)) ||
 	    ini->release_nr < SMC_RELEASE_1)
@@ -1251,6 +1254,8 @@ int smc_clc_clnt_v2x_features_validate(struct smc_clc_first_contact_ext *fce,
 			return SMC_CLC_DECL_MAXLINKERR;
 		ini->max_links = fce_v2x->max_links;
 	}
+	/* common supplemental features of server and client */
+	ini->feature_mask = ntohs(fce_v2x->feature_mask) & SMC_FEATURE_MASK;
 
 	return 0;
 }
@@ -1279,6 +1284,8 @@ int smc_clc_v2x_features_confirm_check(struct smc_clc_msg_accept_confirm *cclc,
 		if (fce_v2x->max_links != ini->max_links)
 			return SMC_CLC_DECL_MAXLINKERR;
 	}
+	/* common supplemental features returned by client */
+	ini->feature_mask = ntohs(fce_v2x->feature_mask);
 
 	return 0;
 }

net/smc/smc_clc.h

@@ -138,7 +138,8 @@ struct smc_clc_v2_extension {
 	u8 roce[16];		/* RoCEv2 GID */
 	u8 max_conns;
 	u8 max_links;
-	u8 reserved[14];
+	__be16 feature_mask;
+	u8 reserved[12];
 	u8 user_eids[][SMC_MAX_EID_LEN];
 };
 
@@ -240,9 +241,14 @@ struct smc_clc_first_contact_ext {
 
 struct smc_clc_first_contact_ext_v2x {
 	struct smc_clc_first_contact_ext fce_v2_base;
-	u8 max_conns; /* for SMC-R only */
-	u8 max_links; /* for SMC-R only */
-	u8 reserved3[2];
+	union {
+		struct {
+			u8 max_conns; /* for SMC-R only */
+			u8 max_links; /* for SMC-R only */
+		};
+		u8 reserved3[2];	/* for SMC-D only */
+	};
+	__be16 feature_mask;
 	__be32 vendor_exp_options;
 	u8 reserved4[8];
 } __packed;		/* format defined in

net/smc/smc_core.h

@@ -401,6 +401,7 @@ struct smc_init_info {
 	u8			max_links;
 	u8			first_contact_peer;
 	u8			first_contact_local;
+	u16			feature_mask;
 	unsigned short		vlan_id;
 	u32			rc;
 	u8			negotiated_eid[SMC_MAX_EID_LEN];