RDMA/bnxt_re: Enable variable size WQEs for user space applications

Add backward compatibility code to enable variable size WQEs only if the
user lib supports it.

Link: https://patch.msgid.link/r/1724042847-1481-6-git-send-email-selvin.xavier@broadcom.comSigned-off-by: Hongguang Gao <hongguang.gao@broadcom.com>
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/hw/bnxt_re/ib_verbs.c

@@ -4233,6 +4233,11 @@ int bnxt_re_alloc_ucontext(struct ib_ucontext *ctx, struct ib_udata *udata)
 			resp.comp_mask |= BNXT_RE_UCNTX_CMASK_POW2_DISABLED;
 			uctx->cmask |= BNXT_RE_UCNTX_CAP_POW2_DISABLED;
 		}
+		if (ureq.comp_mask & BNXT_RE_COMP_MASK_REQ_UCNTX_VAR_WQE_SUPPORT) {
+			resp.comp_mask |= BNXT_RE_UCNTX_CMASK_HAVE_MODE;
+			resp.mode = rdev->chip_ctx->modes.wqe_mode;
+			uctx->cmask |= BNXT_RE_UCNTX_CAP_VAR_WQE_ENABLED;
+		}
 	}
 
 	rc = ib_copy_to_udata(udata, &resp, min(udata->outlen, sizeof(resp)));

include/uapi/rdma/bnxt_re-abi.h

@@ -66,6 +66,7 @@ enum bnxt_re_wqe_mode {
 
 enum {
 	BNXT_RE_COMP_MASK_REQ_UCNTX_POW2_SUPPORT = 0x01,
+	BNXT_RE_COMP_MASK_REQ_UCNTX_VAR_WQE_SUPPORT = 0x02,
 };
 
 struct bnxt_re_uctx_req {