RDMA/ucma: Support write an event into a CM

Enable user-space to inject an event into a CM through it's event
channel. Two new events are added and supported: RDMA_CM_EVENT_USER and
RDMA_CM_EVENT_INTERNAL. With these 2 events a new event parameter "arg"
is supported, which is passed from sender to receiver transparently.

With this feature an application is able to write an event into a CM
channel with a new user-space rdmacm API. For example thread T1 could
write an event with the API:
    rdma_write_cm_event(cm_id, RDMA_CM_EVENT_USER, status, arg);
and thread T2 could receive the event with rdma_get_cm_event().

Signed-off-by: Mark Zhang <markzhang@nvidia.com>
Reviewed-by: Vlad Dumitrescu <vdumitrescu@nvidia.com>
Link: https://patch.msgid.link/fdf49d0b17a45933c5d8c1d90605c9447d9a3c73.1751279794.git.leonro@nvidia.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/core/ucma.c

@@ -1745,6 +1745,55 @@ err_unlock:
 	return ret;
 }
 
+static ssize_t ucma_write_cm_event(struct ucma_file *file,
+				   const char __user *inbuf, int in_len,
+				   int out_len)
+{
+	struct rdma_ucm_write_cm_event cmd;
+	struct rdma_cm_event event = {};
+	struct ucma_event *uevent;
+	struct ucma_context *ctx;
+	int ret = 0;
+
+	if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
+		return -EFAULT;
+
+	if ((cmd.event != RDMA_CM_EVENT_USER) &&
+	    (cmd.event != RDMA_CM_EVENT_INTERNAL))
+		return -EINVAL;
+
+	ctx = ucma_get_ctx(file, cmd.id);
+	if (IS_ERR(ctx))
+		return PTR_ERR(ctx);
+
+	event.event = cmd.event;
+	event.status = cmd.status;
+	event.param.arg = cmd.param.arg;
+
+	uevent = kzalloc(sizeof(*uevent), GFP_KERNEL);
+	if (!uevent) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	uevent->ctx = ctx;
+	uevent->resp.uid = ctx->uid;
+	uevent->resp.id = ctx->id;
+	uevent->resp.event = event.event;
+	uevent->resp.status = event.status;
+	memcpy(uevent->resp.param.arg32, &event.param.arg,
+	       sizeof(event.param.arg));
+
+	mutex_lock(&ctx->file->mut);
+	list_add_tail(&uevent->list, &ctx->file->event_list);
+	mutex_unlock(&ctx->file->mut);
+	wake_up_interruptible(&ctx->file->poll_wait);
+
+out:
+	ucma_put_ctx(ctx);
+	return ret;
+}
+
 static ssize_t (*ucma_cmd_table[])(struct ucma_file *file,
 				   const char __user *inbuf,
 				   int in_len, int out_len) = {
@@ -1771,7 +1820,8 @@ static ssize_t (*ucma_cmd_table[])(struct ucma_file *file,
 	[RDMA_USER_CM_CMD_BIND]		 = ucma_bind,
 	[RDMA_USER_CM_CMD_RESOLVE_ADDR]	 = ucma_resolve_addr,
 	[RDMA_USER_CM_CMD_JOIN_MCAST]	 = ucma_join_multicast,
-	[RDMA_USER_CM_CMD_RESOLVE_IB_SERVICE] = ucma_resolve_ib_service
+	[RDMA_USER_CM_CMD_RESOLVE_IB_SERVICE] = ucma_resolve_ib_service,
+	[RDMA_USER_CM_CMD_WRITE_CM_EVENT] = ucma_write_cm_event,
 };
 
 static ssize_t ucma_write(struct file *filp, const char __user *buf,

include/rdma/rdma_cm.h

@@ -35,7 +35,9 @@ enum rdma_cm_event_type {
 	RDMA_CM_EVENT_ADDR_CHANGE,
 	RDMA_CM_EVENT_TIMEWAIT_EXIT,
 	RDMA_CM_EVENT_ADDRINFO_RESOLVED,
-	RDMA_CM_EVENT_ADDRINFO_ERROR
+	RDMA_CM_EVENT_ADDRINFO_ERROR,
+	RDMA_CM_EVENT_USER,
+	RDMA_CM_EVENT_INTERNAL,
 };
 
 const char *__attribute_const__ rdma_event_msg(enum rdma_cm_event_type event);
@@ -98,6 +100,7 @@ struct rdma_cm_event {
 	union {
 		struct rdma_conn_param	conn;
 		struct rdma_ud_param	ud;
+		u64			arg;
 	} param;
 	struct rdma_ucm_ece ece;
 };

include/uapi/rdma/rdma_user_cm.h

@@ -68,7 +68,8 @@ enum {
 	RDMA_USER_CM_CMD_BIND,
 	RDMA_USER_CM_CMD_RESOLVE_ADDR,
 	RDMA_USER_CM_CMD_JOIN_MCAST,
-	RDMA_USER_CM_CMD_RESOLVE_IB_SERVICE
+	RDMA_USER_CM_CMD_RESOLVE_IB_SERVICE,
+	RDMA_USER_CM_CMD_WRITE_CM_EVENT,
 };
 
 /* See IBTA Annex A11, servies ID bytes 4 & 5 */
@@ -304,6 +305,7 @@ struct rdma_ucm_event_resp {
 	union {
 		struct rdma_ucm_conn_param conn;
 		struct rdma_ucm_ud_param   ud;
+		__u32 arg32[2];
 	} param;
 	__u32 reserved;
 	struct rdma_ucm_ece ece;
@@ -362,4 +364,16 @@ struct rdma_ucm_resolve_ib_service {
 	__u32 id;
 	struct rdma_ucm_ib_service ibs;
 };
+
+struct rdma_ucm_write_cm_event {
+	__u32 id;
+	__u32 reserved;
+	__u32 event;
+	__u32 status;
+	union {
+		struct rdma_ucm_conn_param conn;
+		struct rdma_ucm_ud_param ud;
+		__u64 arg;
+	} param;
+};
 #endif /* RDMA_USER_CM_H */