IB/uverbs: Allow CQ moderation with modify CQ

Uverbs support in modify_cq for CQ moderation only.
Gives ability to change cq_max_count and cq_period.
CQ moderation enhance performance by moderating the number
of CQEs needed to create an event instead of application
having to suffer from event per-CQE.
To achieve CQ moderation the application needs to set cq_max_count
and cq_period.
cq_max_count - defines the number of CQEs needed to create an event.
cq_period - defines the timeout (micro seconds) between last
            event and a new one that will occur even if
	    cq_max_count was not satisfied
Signed-off-by: Yonatan Cohen <yonatanc@mellanox.com>
Reviewed-by: Majd Dibbiny <majd@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/uverbs.h

@@ -306,5 +306,6 @@ IB_UVERBS_DECLARE_EX_CMD(destroy_wq);
 IB_UVERBS_DECLARE_EX_CMD(create_rwq_ind_table);
 IB_UVERBS_DECLARE_EX_CMD(destroy_rwq_ind_table);
 IB_UVERBS_DECLARE_EX_CMD(modify_qp);
+IB_UVERBS_DECLARE_EX_CMD(modify_cq);
 
 #endif /* UVERBS_H */

drivers/infiniband/core/uverbs_cmd.c

@@ -3856,3 +3856,45 @@ int ib_uverbs_ex_query_device(struct ib_uverbs_file *file,
 	err = ib_copy_to_udata(ucore, &resp, resp.response_length);
 	return err;
 }
+
+int ib_uverbs_ex_modify_cq(struct ib_uverbs_file *file,
+			   struct ib_device *ib_dev,
+			   struct ib_udata *ucore,
+			   struct ib_udata *uhw)
+{
+	struct ib_uverbs_ex_modify_cq cmd = {};
+	struct ib_cq *cq;
+	size_t required_cmd_sz;
+	int ret;
+
+	required_cmd_sz = offsetof(typeof(cmd), reserved) +
+				sizeof(cmd.reserved);
+	if (ucore->inlen < required_cmd_sz)
+		return -EINVAL;
+
+	/* sanity checks */
+	if (ucore->inlen > sizeof(cmd) &&
+	    !ib_is_udata_cleared(ucore, sizeof(cmd),
+				 ucore->inlen - sizeof(cmd)))
+		return -EOPNOTSUPP;
+
+	ret = ib_copy_from_udata(&cmd, ucore, min(sizeof(cmd), ucore->inlen));
+	if (ret)
+		return ret;
+
+	if (!cmd.attr_mask || cmd.reserved)
+		return -EINVAL;
+
+	if (cmd.attr_mask > IB_CQ_MODERATE)
+		return -EOPNOTSUPP;
+
+	cq = uobj_get_obj_read(cq, cmd.cq_handle, file->ucontext);
+	if (!cq)
+		return -EINVAL;
+
+	ret = ib_modify_cq(cq, cmd.attr.cq_count, cmd.attr.cq_period);
+
+	uobj_put_obj_read(cq);
+
+	return ret;
+}

drivers/infiniband/core/uverbs_main.c

@@ -128,6 +128,7 @@ static int (*uverbs_ex_cmd_table[])(struct ib_uverbs_file *file,
 	[IB_USER_VERBS_EX_CMD_CREATE_RWQ_IND_TBL] = ib_uverbs_ex_create_rwq_ind_table,
 	[IB_USER_VERBS_EX_CMD_DESTROY_RWQ_IND_TBL] = ib_uverbs_ex_destroy_rwq_ind_table,
 	[IB_USER_VERBS_EX_CMD_MODIFY_QP]        = ib_uverbs_ex_modify_qp,
+	[IB_USER_VERBS_EX_CMD_MODIFY_CQ]        = ib_uverbs_ex_modify_cq,
 };
 
 static void ib_uverbs_add_one(struct ib_device *device);

include/rdma/ib_verbs.h

@@ -311,6 +311,10 @@ struct ib_cq_init_attr {
 	u32		flags;
 };
 
+enum ib_cq_attr_mask {
+	IB_CQ_MODERATE = 1 << 0,
+};
+
 struct ib_device_attr {
 	u64			fw_ver;
 	__be64			sys_image_guid;

include/uapi/rdma/ib_user_verbs.h

@@ -100,7 +100,8 @@ enum {
 	IB_USER_VERBS_EX_CMD_MODIFY_WQ,
 	IB_USER_VERBS_EX_CMD_DESTROY_WQ,
 	IB_USER_VERBS_EX_CMD_CREATE_RWQ_IND_TBL,
-	IB_USER_VERBS_EX_CMD_DESTROY_RWQ_IND_TBL
+	IB_USER_VERBS_EX_CMD_DESTROY_RWQ_IND_TBL,
+	IB_USER_VERBS_EX_CMD_MODIFY_CQ
 };
 
 /*
@@ -1150,6 +1151,18 @@ struct ib_uverbs_ex_destroy_rwq_ind_table  {
 	__u32 ind_tbl_handle;
 };
 
+struct ib_uverbs_cq_moderation {
+	__u16 cq_count;
+	__u16 cq_period;
+};
+
+struct ib_uverbs_ex_modify_cq {
+	__u32 cq_handle;
+	__u32 attr_mask;
+	struct ib_uverbs_cq_moderation attr;
+	__u32 reserved;
+};
+
 #define IB_DEVICE_NAME_MAX 64
 
 #endif /* IB_USER_VERBS_H */