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>

3 files changed, 44 insertions, 0 deletions

diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
index ee2739ae4305..deccefb71a6b 100644
--- a/drivers/infiniband/core/uverbs.h
+++ b/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 */
diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index 8ca36843ef38..3c2673cd4090 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -3856,3 +3856,45 @@ end:
 	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;
+}
diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index b5febfd84ee5..381fd9c096ae 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/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);