smc: remote memory buffers (RMBs)

* allocate data RMB memory for sending and receiving
* size depends on the maximum socket send and receive buffers
* allocated RMBs are kept during life time of the owning link group
* map the allocated RMBs to DMA

Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/smc/af_smc.c

@@ -249,6 +249,8 @@ static void smc_conn_save_peer_info(struct smc_sock *smc,
 				    struct smc_clc_msg_accept_confirm *clc)
 {
 	smc->conn.peer_conn_idx = clc->conn_idx;
+	smc->conn.peer_rmbe_size = smc_uncompress_bufsize(clc->rmbe_size);
+	atomic_set(&smc->conn.peer_rmbe_space, smc->conn.peer_rmbe_size);
 }
 
 static void smc_link_save_peer_info(struct smc_link *link,
@@ -323,6 +325,18 @@ static int smc_connect_rdma(struct smc_sock *smc)
 	link = &smc->conn.lgr->lnk[SMC_SINGLE_LINK];
 
 	smc_conn_save_peer_info(smc, &aclc);
+
+	rc = smc_sndbuf_create(smc);
+	if (rc) {
+		reason_code = SMC_CLC_DECL_MEM;
+		goto decline_rdma_unlock;
+	}
+	rc = smc_rmb_create(smc);
+	if (rc) {
+		reason_code = SMC_CLC_DECL_MEM;
+		goto decline_rdma_unlock;
+	}
+
 	if (local_contact == SMC_FIRST_CONTACT)
 		smc_link_save_peer_info(link, &aclc);
 	/* tbd in follow-on patch: more steps to setup RDMA communcication,
@@ -598,9 +612,16 @@ static void smc_listen_work(struct work_struct *work)
 	}
 	link = &new_smc->conn.lgr->lnk[SMC_SINGLE_LINK];
 
-	/* tbd in follow-on patch: more steps to setup RDMA communcication,
-	 * create rmbs, map rmbs
-	 */
+	rc = smc_sndbuf_create(new_smc);
+	if (rc) {
+		reason_code = SMC_CLC_DECL_MEM;
+		goto decline_rdma;
+	}
+	rc = smc_rmb_create(new_smc);
+	if (rc) {
+		reason_code = SMC_CLC_DECL_MEM;
+		goto decline_rdma;
+	}
 
 	rc = smc_clc_send_accept(new_smc, local_contact);
 	if (rc)
@@ -1047,6 +1068,8 @@ static int smc_create(struct net *net, struct socket *sock, int protocol,
 			      IPPROTO_TCP, &smc->clcsock);
 	if (rc)
 		sk_common_release(sk);
+	smc->sk.sk_sndbuf = max(smc->clcsock->sk->sk_sndbuf, SMC_BUF_MIN_SIZE);
+	smc->sk.sk_rcvbuf = max(smc->clcsock->sk->sk_rcvbuf, SMC_BUF_MIN_SIZE);
 
 out:
 	return rc;

net/smc/smc.h

@@ -34,6 +34,16 @@ struct smc_connection {
 	struct smc_link_group	*lgr;		/* link group of connection */
 	u32			alert_token_local; /* unique conn. id */
 	u8			peer_conn_idx;	/* from tcp handshake */
+	int			peer_rmbe_size;	/* size of peer rx buffer */
+	atomic_t		peer_rmbe_space;/* remaining free bytes in peer
+						 * rmbe
+						 */
+
+	struct smc_buf_desc	*sndbuf_desc;	/* send buffer descriptor */
+	int			sndbuf_size;	/* sndbuf size <== sock wmem */
+	struct smc_buf_desc	*rmb_desc;	/* RMBE descriptor */
+	int			rmbe_size;	/* RMBE size <== sock rmem */
+	int			rmbe_size_short;/* compressed notation */
 };
 
 struct smc_sock {				/* smc sock container */
@@ -76,6 +86,41 @@ static inline u32 ntoh24(u8 *net)
 	return be32_to_cpu(t);
 }
 
+#define SMC_BUF_MIN_SIZE 16384		/* minimum size of an RMB */
+
+#define SMC_RMBE_SIZES	16	/* number of distinct sizes for an RMBE */
+/* theoretically, the RFC states that largest size would be 512K,
+ * i.e. compressed 5 and thus 6 sizes (0..5), despite
+ * struct smc_clc_msg_accept_confirm.rmbe_size being a 4 bit value (0..15)
+ */
+
+/* convert the RMB size into the compressed notation - minimum 16K.
+ * In contrast to plain ilog2, this rounds towards the next power of 2,
+ * so the socket application gets at least its desired sndbuf / rcvbuf size.
+ */
+static inline u8 smc_compress_bufsize(int size)
+{
+	u8 compressed;
+
+	if (size <= SMC_BUF_MIN_SIZE)
+		return 0;
+
+	size = (size - 1) >> 14;
+	compressed = ilog2(size) + 1;
+	if (compressed >= SMC_RMBE_SIZES)
+		compressed = SMC_RMBE_SIZES - 1;
+	return compressed;
+}
+
+/* convert the RMB size from compressed notation into integer */
+static inline int smc_uncompress_bufsize(u8 compressed)
+{
+	u32 size;
+
+	size = 0x00000001 << (((int)compressed) + 14);
+	return (int)size;
+}
+
 #ifdef CONFIG_XFRM
 static inline bool using_ipsec(struct smc_sock *smc)
 {

net/smc/smc_clc.c

@@ -252,13 +252,13 @@ int smc_clc_send_accept(struct smc_sock *new_smc, int srv_first_contact)
 	       SMC_GID_SIZE);
 	memcpy(&aclc.lcl.mac, link->smcibdev->mac[link->ibport - 1],
 	       sizeof(link->smcibdev->mac[link->ibport - 1]));
-
-	/* tbd in follow-on patch: fill in rmb-related values */
-
 	hton24(aclc.qpn, link->roce_qp->qp_num);
 	aclc.conn_idx = 1;			/* as long as 1 RMB = 1 RMBE */
 	aclc.rmbe_alert_token = htonl(conn->alert_token_local);
 	aclc.qp_mtu = link->path_mtu;
+	aclc.rmbe_size = conn->rmbe_size_short,
+	aclc.rmb_dma_addr =
+		cpu_to_be64((u64)conn->rmb_desc->dma_addr[SMC_SINGLE_LINK]);
 	hton24(aclc.psn, link->psn_initial);
 	memcpy(aclc.trl.eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER));