RDMA/uverbs: Add a common way to create CQ with umem

Add ioctl command attributes and a common handling for the option to
create CQs with memory buffers passed from userspace. When required
attributes are supplied, create umem and provide it for driver's use.
The extension enables creation of CQs on top of preallocated CPU
virtual or device memory buffers, by supplying VA or dmabuf fd, in a
common way.
Drivers can support this flow by initializing a new create_cq_umem fp
field in their ops struct, with a function that can handle the new
parameter.

Signed-off-by: Michael Margolin <mrgolin@amazon.com>
Link: https://patch.msgid.link/20250708202308.24783-2-mrgolin@amazon.com
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/core/device.c

@@ -2728,6 +2728,7 @@ void ib_set_device_ops(struct ib_device *dev, const struct ib_device_ops *ops)
 	SET_DEVICE_OP(dev_ops, create_ah);
 	SET_DEVICE_OP(dev_ops, create_counters);
 	SET_DEVICE_OP(dev_ops, create_cq);
+	SET_DEVICE_OP(dev_ops, create_cq_umem);
 	SET_DEVICE_OP(dev_ops, create_flow);
 	SET_DEVICE_OP(dev_ops, create_qp);
 	SET_DEVICE_OP(dev_ops, create_rwq_ind_table);

drivers/infiniband/core/uverbs_std_types_cq.c

@@ -64,15 +64,21 @@ static int UVERBS_HANDLER(UVERBS_METHOD_CQ_CREATE)(
 	struct ib_ucq_object *obj = container_of(
 		uverbs_attr_get_uobject(attrs, UVERBS_ATTR_CREATE_CQ_HANDLE),
 		typeof(*obj), uevent.uobject);
+	struct ib_uverbs_completion_event_file *ev_file = NULL;
 	struct ib_device *ib_dev = attrs->context->device;
-	int ret;
+	struct ib_umem_dmabuf *umem_dmabuf;
-	u64 user_handle;
 	struct ib_cq_init_attr attr = {};
-	struct ib_cq                   *cq;
-	struct ib_uverbs_completion_event_file    *ev_file = NULL;
 	struct ib_uobject *ev_file_uobj;
+	struct ib_umem *umem = NULL;
+	u64 buffer_length;
+	u64 buffer_offset;
+	struct ib_cq *cq;
+	u64 user_handle;
+	u64 buffer_va;
+	int buffer_fd;
+	int ret;
 
-	if (!ib_dev->ops.create_cq || !ib_dev->ops.destroy_cq)
+	if ((!ib_dev->ops.create_cq && !ib_dev->ops.create_cq_umem) || !ib_dev->ops.destroy_cq)
 		return -EOPNOTSUPP;
 
 	ret = uverbs_copy_from(&attr.comp_vector, attrs,
@@ -112,9 +118,66 @@ static int UVERBS_HANDLER(UVERBS_METHOD_CQ_CREATE)(
 	INIT_LIST_HEAD(&obj->comp_list);
 	INIT_LIST_HEAD(&obj->uevent.event_list);
 
+	if (uverbs_attr_is_valid(attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_VA)) {
+
+		ret = uverbs_copy_from(&buffer_va, attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_VA);
+		if (ret)
+			goto err_event_file;
+
+		ret = uverbs_copy_from(&buffer_length, attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_LENGTH);
+		if (ret)
+			goto err_event_file;
+
+		if (uverbs_attr_is_valid(attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_FD) ||
+		    uverbs_attr_is_valid(attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_OFFSET) ||
+		    !ib_dev->ops.create_cq_umem) {
+			ret = -EINVAL;
+			goto err_event_file;
+		}
+
+		umem = ib_umem_get(ib_dev, buffer_va, buffer_length, IB_ACCESS_LOCAL_WRITE);
+		if (IS_ERR(umem)) {
+			ret = PTR_ERR(umem);
+			goto err_event_file;
+		}
+	} else if (uverbs_attr_is_valid(attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_FD)) {
+
+		ret = uverbs_get_raw_fd(&buffer_fd, attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_FD);
+		if (ret)
+			goto err_event_file;
+
+		ret = uverbs_copy_from(&buffer_offset, attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_OFFSET);
+		if (ret)
+			goto err_event_file;
+
+		ret = uverbs_copy_from(&buffer_length, attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_LENGTH);
+		if (ret)
+			goto err_event_file;
+
+		if (uverbs_attr_is_valid(attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_VA) ||
+		    !ib_dev->ops.create_cq_umem) {
+			ret = -EINVAL;
+			goto err_event_file;
+		}
+
+		umem_dmabuf = ib_umem_dmabuf_get_pinned(ib_dev, buffer_offset, buffer_length,
+							buffer_fd, IB_ACCESS_LOCAL_WRITE);
+		if (IS_ERR(umem_dmabuf)) {
+			ret = PTR_ERR(umem_dmabuf);
+			goto err_event_file;
+		}
+		umem = &umem_dmabuf->umem;
+	} else if (uverbs_attr_is_valid(attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_OFFSET) ||
+		   uverbs_attr_is_valid(attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_LENGTH) ||
+		   !ib_dev->ops.create_cq) {
+		ret = -EINVAL;
+		goto err_event_file;
+	}
+
 	cq = rdma_zalloc_drv_obj(ib_dev, ib_cq);
 	if (!cq) {
 		ret = -ENOMEM;
+		ib_umem_release(umem);
 		goto err_event_file;
 	}
 
@@ -128,7 +191,8 @@ static int UVERBS_HANDLER(UVERBS_METHOD_CQ_CREATE)(
 	rdma_restrack_new(&cq->res, RDMA_RESTRACK_CQ);
 	rdma_restrack_set_name(&cq->res, NULL);
 
-	ret = ib_dev->ops.create_cq(cq, &attr, attrs);
+	ret = umem ? ib_dev->ops.create_cq_umem(cq, &attr, umem, attrs) :
+		ib_dev->ops.create_cq(cq, &attr, attrs);
 	if (ret)
 		goto err_free;
 
@@ -180,6 +244,17 @@ DECLARE_UVERBS_NAMED_METHOD(
 		       UVERBS_OBJECT_ASYNC_EVENT,
 		       UVERBS_ACCESS_READ,
 		       UA_OPTIONAL),
+	UVERBS_ATTR_PTR_IN(UVERBS_ATTR_CREATE_CQ_BUFFER_VA,
+			   UVERBS_ATTR_TYPE(u64),
+			   UA_OPTIONAL),
+	UVERBS_ATTR_PTR_IN(UVERBS_ATTR_CREATE_CQ_BUFFER_LENGTH,
+			   UVERBS_ATTR_TYPE(u64),
+			   UA_OPTIONAL),
+	UVERBS_ATTR_RAW_FD(UVERBS_ATTR_CREATE_CQ_BUFFER_FD,
+			   UA_OPTIONAL),
+	UVERBS_ATTR_PTR_IN(UVERBS_ATTR_CREATE_CQ_BUFFER_OFFSET,
+			   UVERBS_ATTR_TYPE(u64),
+			   UA_OPTIONAL),
 	UVERBS_ATTR_UHW());
 
 static int UVERBS_HANDLER(UVERBS_METHOD_CQ_DESTROY)(

include/rdma/ib_verbs.h

@@ -2486,6 +2486,10 @@ struct ib_device_ops {
 	int (*destroy_qp)(struct ib_qp *qp, struct ib_udata *udata);
 	int (*create_cq)(struct ib_cq *cq, const struct ib_cq_init_attr *attr,
 			 struct uverbs_attr_bundle *attrs);
+	int (*create_cq_umem)(struct ib_cq *cq,
+			      const struct ib_cq_init_attr *attr,
+			      struct ib_umem *umem,
+			      struct uverbs_attr_bundle *attrs);
 	int (*modify_cq)(struct ib_cq *cq, u16 cq_count, u16 cq_period);
 	int (*destroy_cq)(struct ib_cq *cq, struct ib_udata *udata);
 	int (*resize_cq)(struct ib_cq *cq, int cqe, struct ib_udata *udata);

include/uapi/rdma/ib_user_ioctl_cmds.h

@@ -105,6 +105,10 @@ enum uverbs_attrs_create_cq_cmd_attr_ids {
 	UVERBS_ATTR_CREATE_CQ_FLAGS,
 	UVERBS_ATTR_CREATE_CQ_RESP_CQE,
 	UVERBS_ATTR_CREATE_CQ_EVENT_FD,
+	UVERBS_ATTR_CREATE_CQ_BUFFER_VA,
+	UVERBS_ATTR_CREATE_CQ_BUFFER_LENGTH,
+	UVERBS_ATTR_CREATE_CQ_BUFFER_FD,
+	UVERBS_ATTR_CREATE_CQ_BUFFER_OFFSET,
 };
 
 enum uverbs_attrs_destroy_cq_cmd_attr_ids {