libeth: xdp: add RSS hash hint and XDP features setup helpers

End the XDP section by adding helpers to setup XDP features, flipping
.ndo_xdp_xmit() support at runtime (in case when it's not always on),
and calculating the queue clean/refill threshold.

Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

1 files changed, 69 insertions, 0 deletions

diff --git a/drivers/net/ethernet/intel/libeth/xdp.c b/drivers/net/ethernet/intel/libeth/xdp.c
index 1607579d65bb..4eb0f3c6cdab 100644
--- a/drivers/net/ethernet/intel/libeth/xdp.c
+++ b/drivers/net/ethernet/intel/libeth/xdp.c
@@ -340,6 +340,75 @@ head:
 }
 EXPORT_SYMBOL_GPL(libeth_xdp_return_buff_bulk);
 
+/* Misc */
+
+/**
+ * libeth_xdp_queue_threshold - calculate XDP queue clean/refill threshold
+ * @count: number of descriptors in the queue
+ *
+ * The threshold is the limit at which RQs start to refill (when the number of
+ * empty buffers exceeds it) and SQs get cleaned up (when the number of free
+ * descriptors goes below it). To speed up hotpath processing, threshold is
+ * always pow-2, closest to 1/4 of the queue length.
+ * Don't call it on hotpath, calculate and cache the threshold during the
+ * queue initialization.
+ *
+ * Return: the calculated threshold.
+ */
+u32 libeth_xdp_queue_threshold(u32 count)
+{
+	u32 quarter, low, high;
+
+	if (likely(is_power_of_2(count)))
+		return count >> 2;
+
+	quarter = DIV_ROUND_CLOSEST(count, 4);
+	low = rounddown_pow_of_two(quarter);
+	high = roundup_pow_of_two(quarter);
+
+	return high - quarter <= quarter - low ? high : low;
+}
+EXPORT_SYMBOL_GPL(libeth_xdp_queue_threshold);
+
+/**
+ * __libeth_xdp_set_features - set XDP features for netdev
+ * @dev: &net_device to configure
+ * @xmo: XDP metadata ops (Rx hints)
+ *
+ * Set all the features libeth_xdp supports. Only the first argument is
+ * necessary.
+ * Use the non-underscored versions in drivers instead.
+ */
+void __libeth_xdp_set_features(struct net_device *dev,
+			       const struct xdp_metadata_ops *xmo)
+{
+	xdp_set_features_flag(dev,
+			      NETDEV_XDP_ACT_BASIC |
+			      NETDEV_XDP_ACT_REDIRECT |
+			      NETDEV_XDP_ACT_NDO_XMIT |
+			      NETDEV_XDP_ACT_RX_SG |
+			      NETDEV_XDP_ACT_NDO_XMIT_SG);
+	dev->xdp_metadata_ops = xmo;
+}
+EXPORT_SYMBOL_GPL(__libeth_xdp_set_features);
+
+/**
+ * libeth_xdp_set_redirect - toggle the XDP redirect feature
+ * @dev: &net_device to configure
+ * @enable: whether XDP is enabled
+ *
+ * Use this when XDPSQs are not always available to dynamically enable
+ * and disable redirect feature.
+ */
+void libeth_xdp_set_redirect(struct net_device *dev, bool enable)
+{
+	if (enable)
+		xdp_features_set_redirect_target(dev, true);
+	else
+		xdp_features_clear_redirect_target(dev);
+}
+EXPORT_SYMBOL_GPL(libeth_xdp_set_redirect);
+
 /* Module */
 
 static const struct libeth_xdp_ops xdp_ops __initconst = {