IB/rdmavt: Add support for rvt_query_device function

With this commit, the drivers using rdmavt need not define query_device
function. But they should fill in the IB device attributes structure
rvt_dev_info.dparms.props

Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Harish Chegondi <harish.chegondi@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/sw/rdmavt/vt.c

@@ -68,10 +68,15 @@ static int rvt_query_device(struct ib_device *ibdev,
 			    struct ib_device_attr *props,
 			    struct ib_udata *uhw)
 {
+	struct rvt_dev_info *rdi = ib_to_rvt(ibdev);
+
+	if (uhw->inlen || uhw->outlen)
+		return -EINVAL;
 	/*
-	 * Return rvt_dev_info.props contents
+	 * Return rvt_dev_info.dparms.props contents
 	 */
-	return -EOPNOTSUPP;
+	*props = rdi->dparms.props;
+	return 0;
 }
 
 static int rvt_modify_device(struct ib_device *device,

include/rdma/rdma_vt.h

@@ -245,7 +245,10 @@ struct rvt_dev_info {
 	 * allocating space for this structure.
 	 *
 	 * The driver will also be responsible for filling in certain members of
-	 * dparms.props
+	 * dparms.props. The driver needs to fill in dparms exactly as it would
+	 * want values reported to a ULP. This will be returned to the caller
+	 * in rdmavt's device. The driver should also therefore refrain from
+	 * modifying this directly after registration with rdmavt.
 	 */
 
 	/* Driver specific properties */