IB/uverbs: Enable QP creation with a given source QP number

Enable QP creation with a given source QP number, the created QP will
use the source QPN as its wire QP number.

To create such a QP, root privileges (i.e. CAP_NET_RAW) are required
from the user application.

This comes as a pre-patch for downstream patches in this series to
allow user space applications to accelerate traffic which is typically
handled by IPoIB ULP.
Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/uverbs_cmd.c

@@ -1383,8 +1383,9 @@ static int create_qp(struct ib_uverbs_file *file,
 		attr.rwq_ind_tbl = ind_tbl;
 	}
 
-	if ((cmd_sz >= offsetof(typeof(*cmd), reserved1) +
-		       sizeof(cmd->reserved1)) && cmd->reserved1) {
+	if (cmd_sz > sizeof(*cmd) &&
+	    !ib_is_udata_cleared(ucore, sizeof(*cmd),
+				 cmd_sz - sizeof(*cmd))) {
 		ret = -EOPNOTSUPP;
 		goto err_put;
 	}
@@ -1482,11 +1483,21 @@ static int create_qp(struct ib_uverbs_file *file,
 				IB_QP_CREATE_MANAGED_SEND |
 				IB_QP_CREATE_MANAGED_RECV |
 				IB_QP_CREATE_SCATTER_FCS |
-				IB_QP_CREATE_CVLAN_STRIPPING)) {
+				IB_QP_CREATE_CVLAN_STRIPPING |
+				IB_QP_CREATE_SOURCE_QPN)) {
 		ret = -EINVAL;
 		goto err_put;
 	}
 
+	if (attr.create_flags & IB_QP_CREATE_SOURCE_QPN) {
+		if (!capable(CAP_NET_RAW)) {
+			ret = -EPERM;
+			goto err_put;
+		}
+
+		attr.source_qpn = cmd->source_qpn;
+	}
+
 	buf = (void *)cmd + sizeof(*cmd);
 	if (cmd_sz > sizeof(*cmd))
 		if (!(buf[0] == 0 && !memcmp(buf, buf + 1,

include/uapi/rdma/ib_user_verbs.h

@@ -578,7 +578,7 @@ struct ib_uverbs_ex_create_qp {
 	__u32 comp_mask;
 	__u32 create_flags;
 	__u32 rwq_ind_tbl_handle;
-	__u32  reserved1;
+	__u32  source_qpn;
 };
 
 struct ib_uverbs_open_qp {