RDMA/uverbs: Export XRC TGT QPs to user space

Allow user space to operate on XRC TGT QPs the same way as other types
of QPs, with one notable exception: since XRC TGT QPs may be shared
among multiple processes, the XRC TGT QP is allowed to exist beyond the
lifetime of the creating process.

The process that creates the QP is allowed to destroy it, but if the
process exits without destroying the QP, then the QP will be left bound
to the lifetime of the XRCD.

TGT QPs are not associated with CQs or a PD.
Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/core/uverbs_cmd.c

@@ -1370,8 +1370,11 @@ ssize_t ib_uverbs_create_qp(struct ib_uverbs_file *file,
 	struct ib_uverbs_create_qp_resp resp;
 	struct ib_udata                 udata;
 	struct ib_uqp_object           *obj;
-	struct ib_pd                   *pd;
-	struct ib_cq                   *scq, *rcq = NULL;
+	struct ib_device	       *device;
+	struct ib_pd                   *pd = NULL;
+	struct ib_xrcd		       *xrcd = NULL;
+	struct ib_uobject	       *uninitialized_var(xrcd_uobj);
+	struct ib_cq                   *scq = NULL, *rcq = NULL;
 	struct ib_srq                  *srq = NULL;
 	struct ib_qp                   *qp;
 	struct ib_qp_init_attr          attr;
@@ -1394,6 +1397,14 @@ ssize_t ib_uverbs_create_qp(struct ib_uverbs_file *file,
 	init_uobj(&obj->uevent.uobject, cmd.user_handle, file->ucontext, &qp_lock_key);
 	down_write(&obj->uevent.uobject.mutex);
 
+	if (cmd.qp_type == IB_QPT_XRC_TGT) {
+		xrcd = idr_read_xrcd(cmd.pd_handle, file->ucontext, &xrcd_uobj);
+		if (!xrcd) {
+			ret = -EINVAL;
+			goto err_put;
+		}
+		device = xrcd->device;
+	} else {
 		pd  = idr_read_pd(cmd.pd_handle, file->ucontext);
 		scq = idr_read_cq(cmd.send_cq_handle, file->ucontext, 0);
 		if (!pd || !scq) {
@@ -1418,12 +1429,15 @@ ssize_t ib_uverbs_create_qp(struct ib_uverbs_file *file,
 				goto err_put;
 			}
 		}
+		device = pd->device;
+	}
 
 	attr.event_handler = ib_uverbs_qp_event_handler;
 	attr.qp_context    = file;
 	attr.send_cq       = scq;
 	attr.recv_cq       = rcq;
 	attr.srq           = srq;
+	attr.xrcd	   = xrcd;
 	attr.sq_sig_type   = cmd.sq_sig_all ? IB_SIGNAL_ALL_WR : IB_SIGNAL_REQ_WR;
 	attr.qp_type       = cmd.qp_type;
 	attr.create_flags  = 0;
@@ -1438,18 +1452,22 @@ ssize_t ib_uverbs_create_qp(struct ib_uverbs_file *file,
 	INIT_LIST_HEAD(&obj->uevent.event_list);
 	INIT_LIST_HEAD(&obj->mcast_list);
 
-	qp = pd->device->create_qp(pd, &attr, &udata);
+	if (cmd.qp_type == IB_QPT_XRC_TGT)
+		qp = ib_create_qp(pd, &attr);
+	else
+		qp = device->create_qp(pd, &attr, &udata);
+
 	if (IS_ERR(qp)) {
 		ret = PTR_ERR(qp);
 		goto err_put;
 	}
 
-	qp->device     	  = pd->device;
+	if (cmd.qp_type != IB_QPT_XRC_TGT) {
+		qp->device	  = device;
 		qp->pd		  = pd;
 		qp->send_cq	  = attr.send_cq;
 		qp->recv_cq	  = attr.recv_cq;
 		qp->srq		  = attr.srq;
-	qp->uobject       = &obj->uevent.uobject;
 		qp->event_handler = attr.event_handler;
 		qp->qp_context	  = attr.qp_context;
 		qp->qp_type	  = attr.qp_type;
@@ -1459,6 +1477,8 @@ ssize_t ib_uverbs_create_qp(struct ib_uverbs_file *file,
 			atomic_inc(&attr.recv_cq->usecnt);
 		if (attr.srq)
 			atomic_inc(&attr.srq->usecnt);
+	}
+	qp->uobject = &obj->uevent.uobject;
 
 	obj->uevent.uobject.object = qp;
 	ret = idr_add_uobj(&ib_uverbs_qp_idr, &obj->uevent.uobject);
@@ -1480,7 +1500,11 @@ ssize_t ib_uverbs_create_qp(struct ib_uverbs_file *file,
 		goto err_copy;
 	}
 
+	if (xrcd)
+		put_xrcd_read(xrcd_uobj);
+	if (pd)
 		put_pd_read(pd);
+	if (scq)
 		put_cq_read(scq);
 	if (rcq && rcq != scq)
 		put_cq_read(rcq);
@@ -1504,6 +1528,8 @@ ssize_t ib_uverbs_create_qp(struct ib_uverbs_file *file,
 	ib_destroy_qp(qp);
 
 err_put:
+	if (xrcd)
+		put_xrcd_read(xrcd_uobj);
 	if (pd)
 		put_pd_read(pd);
 	if (scq)
@@ -1623,6 +1649,9 @@ static int modify_qp_mask(enum ib_qp_type qp_type, int mask)
 	switch (qp_type) {
 	case IB_QPT_XRC_INI:
 		return mask & ~(IB_QP_MAX_DEST_RD_ATOMIC | IB_QP_MIN_RNR_TIMER);
+	case IB_QPT_XRC_TGT:
+		return mask & ~(IB_QP_MAX_QP_RD_ATOMIC | IB_QP_RETRY_CNT |
+				IB_QP_RNR_RETRY);
 	default:
 		return mask;
 	}

drivers/infiniband/core/uverbs_main.c

@@ -206,8 +206,12 @@ static int ib_uverbs_cleanup_ucontext(struct ib_uverbs_file *file,
 			container_of(uobj, struct ib_uqp_object, uevent.uobject);
 
 		idr_remove_uobj(&ib_uverbs_qp_idr, uobj);
+		if (qp->qp_type == IB_QPT_XRC_TGT) {
+			ib_release_qp(qp);
+		} else {
 			ib_uverbs_detach_umcast(qp, uqp);
 			ib_destroy_qp(qp);
+		}
 		ib_uverbs_release_uevent(file, &uqp->uevent);
 		kfree(uqp);
 	}