RDMA/efa: Expose minimum SQ size

The device reports the minimum SQ size required for creation.

This patch queries the min SQ size and reports it back to the userspace
library.

Link: https://lore.kernel.org/r/20200722140312.3651-3-galpress@amazon.comReviewed-by: Firas JahJah <firasj@amazon.com>
Reviewed-by: Shadi Ammouri <sammouri@amazon.com>
Signed-off-by: Gal Pressman <galpress@amazon.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/hw/efa/efa_admin_cmds_defs.h

@@ -606,8 +606,8 @@ struct efa_admin_feature_queue_attr_desc {
 	/* Number of sub-CQs to be created for each CQ */
 	u16 sub_cqs_per_cq;
 
-	/* MBZ */
-	u16 reserved;
+	/* Minimum number of WQEs per SQ */
+	u16 min_sq_depth;
 
 	/* Maximum number of SGEs (buffers) allowed for a single send WQE */
 	u16 max_wr_send_sges;

drivers/infiniband/hw/efa/efa_com_cmd.c

@@ -481,6 +481,7 @@ int efa_com_get_device_attr(struct efa_com_dev *edev,
 	result->sub_cqs_per_cq = resp.u.queue_attr.sub_cqs_per_cq;
 	result->max_wr_rdma_sge = resp.u.queue_attr.max_wr_rdma_sges;
 	result->max_tx_batch = resp.u.queue_attr.max_tx_batch;
+	result->min_sq_depth = resp.u.queue_attr.min_sq_depth;
 
 	err = efa_com_get_feature(edev, &resp, EFA_ADMIN_NETWORK_ATTR);
 	if (err) {

drivers/infiniband/hw/efa/efa_com_cmd.h

@@ -128,6 +128,7 @@ struct efa_com_get_device_attr_result {
 	u16 max_rq_sge;
 	u16 max_wr_rdma_sge;
 	u16 max_tx_batch;
+	u16 min_sq_depth;
 	u8 db_bar;
 };
 

drivers/infiniband/hw/efa/efa_verbs.c

@@ -1526,6 +1526,7 @@ int efa_alloc_ucontext(struct ib_ucontext *ibucontext, struct ib_udata *udata)
 	resp.inline_buf_size = dev->dev_attr.inline_buf_size;
 	resp.max_llq_size = dev->dev_attr.max_llq_size;
 	resp.max_tx_batch = dev->dev_attr.max_tx_batch;
+	resp.min_sq_wr = dev->dev_attr.min_sq_depth;
 
 	if (udata && udata->outlen) {
 		err = ib_copy_to_udata(udata, &resp,

include/uapi/rdma/efa-abi.h

@@ -32,7 +32,8 @@ struct efa_ibv_alloc_ucontext_resp {
 	__u16 inline_buf_size;
 	__u32 max_llq_size; /* bytes */
 	__u16 max_tx_batch; /* units of 64 bytes */
-	__u8 reserved_90[6];
+	__u16 min_sq_wr;
+	__u8 reserved_a0[4];
 };
 
 struct efa_ibv_alloc_pd_resp {