[PATCH for-next v10 3/6] RDMA/core: Expose Completion Counter capabilities to userspace

[Michael Margolin <mrgolin@amazon.com>]

Add a dedicated query interface for completion counter capabilities
via UVERBS_METHOD_QUERY_COMP_CNTR_CAPS on the device object.

The query returns the maximum number of counters, maximum counter
value, and a bitmask of supported QP attach operations. Each field
is an optional ioctl attribute, allowing userspace to request only
the capabilities it needs.

Drivers implement the query_comp_cntr_caps operation to report
device-specific capabilities.

Reviewed-by: Yonatan Nachum <ynachum@amazon.com>
Signed-off-by: Michael Margolin <mrgolin@amazon.com>
---
 drivers/infiniband/core/device.c              |  1 +
 .../infiniband/core/uverbs_std_types_device.c | 51 ++++++++++++++++++-
 include/rdma/ib_verbs.h                       |  9 ++++
 include/uapi/rdma/ib_user_ioctl_cmds.h        |  7 +++
 4 files changed, 67 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index a4c57279f19d..ddf75867ac61 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -2829,6 +2829,7 @@ void ib_set_device_ops(struct ib_device *dev, const struct ib_device_ops *ops)
 	SET_DEVICE_OP(dev_ops, post_srq_recv);
 	SET_DEVICE_OP(dev_ops, process_mad);
 	SET_DEVICE_OP(dev_ops, query_ah);
+	SET_DEVICE_OP(dev_ops, query_comp_cntr_caps);
 	SET_DEVICE_OP(dev_ops, query_device);
 	SET_DEVICE_OP(dev_ops, query_gid);
 	SET_DEVICE_OP(dev_ops, query_pkey);
diff --git a/drivers/infiniband/core/uverbs_std_types_device.c b/drivers/infiniband/core/uverbs_std_types_device.c
index 12ca15739cd2..ce0a7de00405 100644
--- a/drivers/infiniband/core/uverbs_std_types_device.c
+++ b/drivers/infiniband/core/uverbs_std_types_device.c
@@ -472,6 +472,42 @@ static int UVERBS_HANDLER(UVERBS_METHOD_QUERY_GID_ENTRY)(
 	return ret;
 }
 
+static int UVERBS_HANDLER(UVERBS_METHOD_QUERY_COMP_CNTR_CAPS)(
+	struct uverbs_attr_bundle *attrs)
+{
+	struct ib_comp_cntr_caps caps = {};
+	struct ib_ucontext *ucontext;
+	struct ib_device *ib_dev;
+	int ret;
+
+	ucontext = ib_uverbs_get_ucontext(attrs);
+	if (IS_ERR(ucontext))
+		return PTR_ERR(ucontext);
+	ib_dev = ucontext->device;
+
+	if (!ib_dev->ops.query_comp_cntr_caps)
+		return -EOPNOTSUPP;
+
+	ret = ib_dev->ops.query_comp_cntr_caps(ib_dev, &caps, attrs);
+	if (ret)
+		return ret;
+
+	ret = uverbs_copy_to(attrs, UVERBS_ATTR_QUERY_COMP_CNTR_CAPS_MAX_COUNTERS,
+			     &caps.max_counters, sizeof(caps.max_counters));
+	if (IS_UVERBS_COPY_ERR(ret))
+		return ret;
+
+	ret = uverbs_copy_to(attrs, UVERBS_ATTR_QUERY_COMP_CNTR_CAPS_MAX_VALUE,
+			     &caps.max_value, sizeof(caps.max_value));
+	if (IS_UVERBS_COPY_ERR(ret))
+		return ret;
+
+	ret = uverbs_copy_to(attrs, UVERBS_ATTR_QUERY_COMP_CNTR_CAPS_SUPPORTED_QP_ATTACH_OPS,
+			     &caps.supported_qp_attach_ops,
+			     sizeof(caps.supported_qp_attach_ops));
+	return IS_UVERBS_COPY_ERR(ret) ? ret : 0;
+}
+
 DECLARE_UVERBS_NAMED_METHOD(
 	UVERBS_METHOD_GET_CONTEXT,
 	UVERBS_ATTR_PTR_OUT(UVERBS_ATTR_GET_CONTEXT_NUM_COMP_VECTORS,
@@ -542,6 +578,18 @@ DECLARE_UVERBS_NAMED_METHOD(
 					       netdev_ifindex),
 			    UA_MANDATORY));
 
+DECLARE_UVERBS_NAMED_METHOD(
+	UVERBS_METHOD_QUERY_COMP_CNTR_CAPS,
+	UVERBS_ATTR_PTR_OUT(UVERBS_ATTR_QUERY_COMP_CNTR_CAPS_MAX_COUNTERS,
+			    UVERBS_ATTR_TYPE(u32),
+			    UA_OPTIONAL),
+	UVERBS_ATTR_PTR_OUT(UVERBS_ATTR_QUERY_COMP_CNTR_CAPS_MAX_VALUE,
+			    UVERBS_ATTR_TYPE(u64),
+			    UA_OPTIONAL),
+	UVERBS_ATTR_PTR_OUT(UVERBS_ATTR_QUERY_COMP_CNTR_CAPS_SUPPORTED_QP_ATTACH_OPS,
+			    UVERBS_ATTR_TYPE(u32),
+			    UA_OPTIONAL));
+
 DECLARE_UVERBS_GLOBAL_METHODS(UVERBS_OBJECT_DEVICE,
 			      &UVERBS_METHOD(UVERBS_METHOD_GET_CONTEXT),
 			      &UVERBS_METHOD(UVERBS_METHOD_INVOKE_WRITE),
@@ -550,7 +598,8 @@ DECLARE_UVERBS_GLOBAL_METHODS(UVERBS_OBJECT_DEVICE,
 			      &UVERBS_METHOD(UVERBS_METHOD_QUERY_PORT_SPEED),
 			      &UVERBS_METHOD(UVERBS_METHOD_QUERY_CONTEXT),
 			      &UVERBS_METHOD(UVERBS_METHOD_QUERY_GID_TABLE),
-			      &UVERBS_METHOD(UVERBS_METHOD_QUERY_GID_ENTRY));
+			      &UVERBS_METHOD(UVERBS_METHOD_QUERY_GID_ENTRY),
+			      &UVERBS_METHOD(UVERBS_METHOD_QUERY_COMP_CNTR_CAPS));
 
 const struct uapi_definition uverbs_def_obj_device[] = {
 	UAPI_DEF_CHAIN_OBJ_TREE_NAMED(UVERBS_OBJECT_DEVICE),
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 84a8904fbad4..033f4a2c965f 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -1755,6 +1755,12 @@ enum ib_qp_attach_comp_cntr_op {
 	IB_QP_ATTACH_COMP_CNTR_OP_REMOTE_RDMA_WRITE = IB_UVERBS_QP_ATTACH_COMP_CNTR_OP_REMOTE_RDMA_WRITE,
 };
 
+struct ib_comp_cntr_caps {
+	u64 max_value;
+	u32 max_counters;
+	u32 supported_qp_attach_ops; /* Bitmask of enum ib_qp_attach_comp_cntr_op */
+};
+
 struct ib_comp_cntr {
 	struct ib_device *device;
 	struct ib_uobject *uobject;
@@ -2689,6 +2695,9 @@ struct ib_device_ops {
 	int (*modify_comp_cntr)(struct ib_comp_cntr *cc, enum ib_comp_cntr_entry entry,
 				enum ib_comp_cntr_modify_op op, u64 value);
 	int (*read_comp_cntr)(struct ib_comp_cntr *cc, enum ib_comp_cntr_entry entry, u64 *value);
+	int (*query_comp_cntr_caps)(struct ib_device *dev,
+				    struct ib_comp_cntr_caps *caps,
+				    struct uverbs_attr_bundle *attrs);
 	struct ib_mr *(*get_dma_mr)(struct ib_pd *pd, int mr_access_flags);
 	struct ib_mr *(*reg_user_mr)(struct ib_pd *pd, u64 start, u64 length,
 				     u64 virt_addr, int mr_access_flags,
diff --git a/include/uapi/rdma/ib_user_ioctl_cmds.h b/include/uapi/rdma/ib_user_ioctl_cmds.h
index 19a94b91987e..6a3d59d03f54 100644
--- a/include/uapi/rdma/ib_user_ioctl_cmds.h
+++ b/include/uapi/rdma/ib_user_ioctl_cmds.h
@@ -76,6 +76,7 @@ enum uverbs_methods_device {
 	UVERBS_METHOD_QUERY_GID_TABLE,
 	UVERBS_METHOD_QUERY_GID_ENTRY,
 	UVERBS_METHOD_QUERY_PORT_SPEED,
+	UVERBS_METHOD_QUERY_COMP_CNTR_CAPS,
 };
 
 enum uverbs_attrs_invoke_write_cmd_attr_ids {
@@ -94,6 +95,12 @@ enum uverbs_attrs_query_port_speed_cmd_attr_ids {
 	UVERBS_ATTR_QUERY_PORT_SPEED_RESP,
 };
 
+enum uverbs_attrs_query_comp_cntr_caps_attr_ids {
+	UVERBS_ATTR_QUERY_COMP_CNTR_CAPS_MAX_COUNTERS,
+	UVERBS_ATTR_QUERY_COMP_CNTR_CAPS_MAX_VALUE,
+	UVERBS_ATTR_QUERY_COMP_CNTR_CAPS_SUPPORTED_QP_ATTACH_OPS,
+};
+
 enum uverbs_attrs_get_context_attr_ids {
 	UVERBS_ATTR_GET_CONTEXT_NUM_COMP_VECTORS,
 	UVERBS_ATTR_GET_CONTEXT_CORE_SUPPORT,
-- 
2.47.3