IB/ehca: Support small QP queues

eHCA2 supports QP queues that can be as small as 512 bytes. This
greatly reduces memory overhead for consumers that use lots of QPs
with small queues (e.g. RDMA-only QPs). Apart from dealing with
firmware, this code needs to manage bite-sized chunks of kernel pages,
making sure that no kernel page is shared between different protection
domains.

Signed-off-by: Hoang-Nam Nguyen <hnguyen@de.ibm.com>

1 files changed, 97 insertions, 64 deletions

diff --git a/drivers/infiniband/hw/ehca/ehca_qp.c b/drivers/infiniband/hw/ehca/ehca_qp.c
index 483f0ca1acc..b178cba9634 100644
--- a/drivers/infiniband/hw/ehca/ehca_qp.c
+++ b/drivers/infiniband/hw/ehca/ehca_qp.c
@@ -275,34 +275,39 @@ static inline void queue2resp(struct ipzu_queue_resp *resp,
 	resp->toggle_state = queue->toggle_state;
 }
 
-static inline int ll_qp_msg_size(int nr_sge)
-{
-	return 128 << nr_sge;
-}
-
 /*
  * init_qp_queue initializes/constructs r/squeue and registers queue pages.
  */
 static inline int init_qp_queue(struct ehca_shca *shca,
+				struct ehca_pd *pd,
 				struct ehca_qp *my_qp,
 				struct ipz_queue *queue,
 				int q_type,
 				u64 expected_hret,
-				int nr_q_pages,
-				int wqe_size,
-				int nr_sges)
+				struct ehca_alloc_queue_parms *parms,
+				int wqe_size)
 {
-	int ret, cnt, ipz_rc;
+	int ret, cnt, ipz_rc, nr_q_pages;
 	void *vpage;
 	u64 rpage, h_ret;
 	struct ib_device *ib_dev = &shca->ib_device;
 	struct ipz_adapter_handle ipz_hca_handle = shca->ipz_hca_handle;
 
-	if (!nr_q_pages)
+	if (!parms->queue_size)
 		return 0;
 
-	ipz_rc = ipz_queue_ctor(queue, nr_q_pages, EHCA_PAGESIZE,
-				wqe_size, nr_sges);
+	if (parms->is_small) {
+		nr_q_pages = 1;
+		ipz_rc = ipz_queue_ctor(pd, queue, nr_q_pages,
+					128 << parms->page_size,
+					wqe_size, parms->act_nr_sges, 1);
+	} else {
+		nr_q_pages = parms->queue_size;
+		ipz_rc = ipz_queue_ctor(pd, queue, nr_q_pages,
+					EHCA_PAGESIZE, wqe_size,
+					parms->act_nr_sges, 0);
+	}
+
 	if (!ipz_rc) {
 		ehca_err(ib_dev, "Cannot allocate page for queue. ipz_rc=%x",
 			 ipz_rc);
@@ -323,7 +328,7 @@ static inline int init_qp_queue(struct ehca_shca *shca,
 		h_ret = hipz_h_register_rpage_qp(ipz_hca_handle,
 						 my_qp->ipz_qp_handle,
 						 NULL, 0, q_type,
-						 rpage, 1,
+						 rpage, parms->is_small ? 0 : 1,
 						 my_qp->galpas.kernel);
 		if (cnt == (nr_q_pages - 1)) {	/* last page! */
 			if (h_ret != expected_hret) {
@@ -354,10 +359,45 @@ static inline int init_qp_queue(struct ehca_shca *shca,
 	return 0;
 
 init_qp_queue1:
-	ipz_queue_dtor(queue);
+	ipz_queue_dtor(pd, queue);
 	return ret;
 }
 
+static inline int ehca_calc_wqe_size(int act_nr_sge, int is_llqp)
+{
+	if (is_llqp)
+		return 128 << act_nr_sge;
+	else
+		return offsetof(struct ehca_wqe,
+				u.nud.sg_list[act_nr_sge]);
+}
+
+static void ehca_determine_small_queue(struct ehca_alloc_queue_parms *queue,
+				       int req_nr_sge, int is_llqp)
+{
+	u32 wqe_size, q_size;
+	int act_nr_sge = req_nr_sge;
+
+	if (!is_llqp)
+		/* round up #SGEs so WQE size is a power of 2 */
+		for (act_nr_sge = 4; act_nr_sge <= 252;
+		     act_nr_sge = 4 + 2 * act_nr_sge)
+			if (act_nr_sge >= req_nr_sge)
+				break;
+
+	wqe_size = ehca_calc_wqe_size(act_nr_sge, is_llqp);
+	q_size = wqe_size * (queue->max_wr + 1);
+
+	if (q_size <= 512)
+		queue->page_size = 2;
+	else if (q_size <= 1024)
+		queue->page_size = 3;
+	else
+		queue->page_size = 0;
+
+	queue->is_small = (queue->page_size != 0);
+}
+
 /*
  * Create an ib_qp struct that is either a QP or an SRQ, depending on
  * the value of the is_srq parameter. If init_attr and srq_init_attr share
@@ -553,10 +593,20 @@ static struct ehca_qp *internal_create_qp(
 	if (my_qp->recv_cq)
 		parms.recv_cq_handle = my_qp->recv_cq->ipz_cq_handle;
 
-	parms.max_send_wr = init_attr->cap.max_send_wr;
-	parms.max_recv_wr = init_attr->cap.max_recv_wr;
-	parms.max_send_sge = max_send_sge;
-	parms.max_recv_sge = max_recv_sge;
+	parms.squeue.max_wr = init_attr->cap.max_send_wr;
+	parms.rqueue.max_wr = init_attr->cap.max_recv_wr;
+	parms.squeue.max_sge = max_send_sge;
+	parms.rqueue.max_sge = max_recv_sge;
+
+	if (EHCA_BMASK_GET(HCA_CAP_MINI_QP, shca->hca_cap)
+	    && !(context && udata)) { /* no small QP support in userspace ATM */
+		ehca_determine_small_queue(
+			&parms.squeue, max_send_sge, is_llqp);
+		ehca_determine_small_queue(
+			&parms.rqueue, max_recv_sge, is_llqp);
+		parms.qp_storage =
+			(parms.squeue.is_small || parms.rqueue.is_small);
+	}
 
 	h_ret = hipz_h_alloc_resource_qp(shca->ipz_hca_handle, &parms);
 	if (h_ret != H_SUCCESS) {
@@ -570,50 +620,33 @@ static struct ehca_qp *internal_create_qp(
 	my_qp->ipz_qp_handle = parms.qp_handle;
 	my_qp->galpas = parms.galpas;
 
+	swqe_size = ehca_calc_wqe_size(parms.squeue.act_nr_sges, is_llqp);
+	rwqe_size = ehca_calc_wqe_size(parms.rqueue.act_nr_sges, is_llqp);
+
 	switch (qp_type) {
 	case IB_QPT_RC:
-		if (!is_llqp) {
-			swqe_size = offsetof(struct ehca_wqe, u.nud.sg_list[
-					     (parms.act_nr_send_sges)]);
-			rwqe_size = offsetof(struct ehca_wqe, u.nud.sg_list[
-					     (parms.act_nr_recv_sges)]);
-		} else { /* for LLQP we need to use msg size, not wqe size */
-			swqe_size = ll_qp_msg_size(max_send_sge);
-			rwqe_size = ll_qp_msg_size(max_recv_sge);
-			parms.act_nr_send_sges = 1;
-			parms.act_nr_recv_sges = 1;
+		if (is_llqp) {
+			parms.squeue.act_nr_sges = 1;
+			parms.rqueue.act_nr_sges = 1;
 		}
 		break;
-	case IB_QPT_UC:
-		swqe_size = offsetof(struct ehca_wqe,
-				     u.nud.sg_list[parms.act_nr_send_sges]);
-		rwqe_size = offsetof(struct ehca_wqe,
-				     u.nud.sg_list[parms.act_nr_recv_sges]);
-		break;
-
 	case IB_QPT_UD:
 	case IB_QPT_GSI:
 	case IB_QPT_SMI:
+		/* UD circumvention */
 		if (is_llqp) {
-			swqe_size = ll_qp_msg_size(parms.act_nr_send_sges);
-			rwqe_size = ll_qp_msg_size(parms.act_nr_recv_sges);
-			parms.act_nr_send_sges = 1;
-			parms.act_nr_recv_sges = 1;
+			parms.squeue.act_nr_sges = 1;
+			parms.rqueue.act_nr_sges = 1;
 		} else {
-			/* UD circumvention */
-			parms.act_nr_send_sges -= 2;
-			parms.act_nr_recv_sges -= 2;
-			swqe_size = offsetof(struct ehca_wqe, u.ud_av.sg_list[
-						     parms.act_nr_send_sges]);
-			rwqe_size = offsetof(struct ehca_wqe, u.ud_av.sg_list[
-						     parms.act_nr_recv_sges]);
+			parms.squeue.act_nr_sges -= 2;
+			parms.rqueue.act_nr_sges -= 2;
 		}
 
 		if (IB_QPT_GSI == qp_type || IB_QPT_SMI == qp_type) {
-			parms.act_nr_send_wqes = init_attr->cap.max_send_wr;
-			parms.act_nr_recv_wqes = init_attr->cap.max_recv_wr;
-			parms.act_nr_send_sges = init_attr->cap.max_send_sge;
-			parms.act_nr_recv_sges = init_attr->cap.max_recv_sge;
+			parms.squeue.act_nr_wqes = init_attr->cap.max_send_wr;
+			parms.rqueue.act_nr_wqes = init_attr->cap.max_recv_wr;
+			parms.squeue.act_nr_sges = init_attr->cap.max_send_sge;
+			parms.rqueue.act_nr_sges = init_attr->cap.max_recv_sge;
 			ib_qp_num = (qp_type == IB_QPT_SMI) ? 0 : 1;
 		}
 
@@ -626,10 +659,9 @@ static struct ehca_qp *internal_create_qp(
 	/* initialize r/squeue and register queue pages */
 	if (HAS_SQ(my_qp)) {
 		ret = init_qp_queue(
-			shca, my_qp, &my_qp->ipz_squeue, 0,
+			shca, my_pd, my_qp, &my_qp->ipz_squeue, 0,
 			HAS_RQ(my_qp) ? H_PAGE_REGISTERED : H_SUCCESS,
-			parms.nr_sq_pages, swqe_size,
-			parms.act_nr_send_sges);
+			&parms.squeue, swqe_size);
 		if (ret) {
 			ehca_err(pd->device, "Couldn't initialize squeue "
 				 "and pages  ret=%x", ret);
@@ -639,9 +671,8 @@ static struct ehca_qp *internal_create_qp(
 
 	if (HAS_RQ(my_qp)) {
 		ret = init_qp_queue(
-			shca, my_qp, &my_qp->ipz_rqueue, 1,
-			H_SUCCESS, parms.nr_rq_pages, rwqe_size,
-			parms.act_nr_recv_sges);
+			shca, my_pd, my_qp, &my_qp->ipz_rqueue, 1,
+			H_SUCCESS, &parms.rqueue, rwqe_size);
 		if (ret) {
 			ehca_err(pd->device, "Couldn't initialize rqueue "
 				 "and pages ret=%x", ret);
@@ -671,10 +702,10 @@ static struct ehca_qp *internal_create_qp(
 	}
 
 	init_attr->cap.max_inline_data = 0; /* not supported yet */
-	init_attr->cap.max_recv_sge = parms.act_nr_recv_sges;
-	init_attr->cap.max_recv_wr = parms.act_nr_recv_wqes;
-	init_attr->cap.max_send_sge = parms.act_nr_send_sges;
-	init_attr->cap.max_send_wr = parms.act_nr_send_wqes;
+	init_attr->cap.max_recv_sge = parms.rqueue.act_nr_sges;
+	init_attr->cap.max_recv_wr = parms.rqueue.act_nr_wqes;
+	init_attr->cap.max_send_sge = parms.squeue.act_nr_sges;
+	init_attr->cap.max_send_wr = parms.squeue.act_nr_wqes;
 	my_qp->init_attr = *init_attr;
 
 	/* NOTE: define_apq0() not supported yet */
@@ -708,6 +739,8 @@ static struct ehca_qp *internal_create_qp(
 		resp.ext_type = my_qp->ext_type;
 		resp.qkey = my_qp->qkey;
 		resp.real_qp_num = my_qp->real_qp_num;
+		resp.ipz_rqueue.offset = my_qp->ipz_rqueue.offset;
+		resp.ipz_squeue.offset = my_qp->ipz_squeue.offset;
 		if (HAS_SQ(my_qp))
 			queue2resp(&resp.ipz_squeue, &my_qp->ipz_squeue);
 		if (HAS_RQ(my_qp))
@@ -724,11 +757,11 @@ static struct ehca_qp *internal_create_qp(
 
 create_qp_exit4:
 	if (HAS_RQ(my_qp))
-		ipz_queue_dtor(&my_qp->ipz_rqueue);
+		ipz_queue_dtor(my_pd, &my_qp->ipz_rqueue);
 
 create_qp_exit3:
 	if (HAS_SQ(my_qp))
-		ipz_queue_dtor(&my_qp->ipz_squeue);
+		ipz_queue_dtor(my_pd, &my_qp->ipz_squeue);
 
 create_qp_exit2:
 	hipz_h_destroy_qp(shca->ipz_hca_handle, my_qp);
@@ -1735,9 +1768,9 @@ static int internal_destroy_qp(struct ib_device *dev, struct ehca_qp *my_qp,
 	}
 
 	if (HAS_RQ(my_qp))
-		ipz_queue_dtor(&my_qp->ipz_rqueue);
+		ipz_queue_dtor(my_pd, &my_qp->ipz_rqueue);
 	if (HAS_SQ(my_qp))
-		ipz_queue_dtor(&my_qp->ipz_squeue);
+		ipz_queue_dtor(my_pd, &my_qp->ipz_squeue);
 	kmem_cache_free(qp_cache, my_qp);
 	return 0;
 }