IB/core: Add on demand paging caps to ib_uverbs_ex_query_device

Add on-demand paging capabilities reporting to the extended query device verb.

Yann Droneaud writes:

    Note: as offsetof() is used to retrieve the size of the lower chunk
    of the response, beware that it only works if the upper chunk
    is right after, without any implicit padding. And, as the size of
    the latter chunk is added to the base size, implicit padding at the
    end of the structure is not taken in account. Both point must be
    taken in account when extending the uverbs functionalities.

Signed-off-by: Haggai Eran <haggaie@mellanox.com>
Reviewed-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/core/uverbs_cmd.c

@@ -3318,7 +3318,7 @@ int ib_uverbs_ex_query_device(struct ib_uverbs_file *file,
 	if (cmd.reserved)
 		return -EINVAL;
 
-	resp.response_length = sizeof(resp);
+	resp.response_length = offsetof(typeof(resp), odp_caps);
 
 	if (ucore->outlen < resp.response_length)
 		return -ENOSPC;
@@ -3330,6 +3330,24 @@ int ib_uverbs_ex_query_device(struct ib_uverbs_file *file,
 	copy_query_dev_fields(file, &resp.base, &attr);
 	resp.comp_mask = 0;
 
+	if (ucore->outlen < resp.response_length + sizeof(resp.odp_caps))
+		goto end;
+
+#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
+	resp.odp_caps.general_caps = attr.odp_caps.general_caps;
+	resp.odp_caps.per_transport_caps.rc_odp_caps =
+		attr.odp_caps.per_transport_caps.rc_odp_caps;
+	resp.odp_caps.per_transport_caps.uc_odp_caps =
+		attr.odp_caps.per_transport_caps.uc_odp_caps;
+	resp.odp_caps.per_transport_caps.ud_odp_caps =
+		attr.odp_caps.per_transport_caps.ud_odp_caps;
+	resp.odp_caps.reserved = 0;
+#else
+	memset(&resp.odp_caps, 0, sizeof(resp.odp_caps));
+#endif
+	resp.response_length += sizeof(resp.odp_caps);
+
+end:
 	err = ib_copy_to_udata(ucore, &resp, resp.response_length);
 	if (err)
 		return err;

include/uapi/rdma/ib_user_verbs.h

@@ -207,10 +207,21 @@ struct ib_uverbs_ex_query_device {
 	__u32 reserved;
 };
 
+struct ib_uverbs_odp_caps {
+	__u64 general_caps;
+	struct {
+		__u32 rc_odp_caps;
+		__u32 uc_odp_caps;
+		__u32 ud_odp_caps;
+	} per_transport_caps;
+	__u32 reserved;
+};
+
 struct ib_uverbs_ex_query_device_resp {
 	struct ib_uverbs_query_device_resp base;
 	__u32 comp_mask;
 	__u32 response_length;
+	struct ib_uverbs_odp_caps odp_caps;
 };
 
 struct ib_uverbs_query_port {