ice: store max_frame and rx_buf_len only in ice_rx_ring

The max_frame and rx_buf_len fields of the VSI set the maximum frame size
for packets on the wire, and configure the size of the Rx buffer. In the
hardware, these are per-queue configuration. Most VSI types use a simple
method to determine the size of the buffers for all queues.

However, VFs may potentially configure different values for each queue.
While the Linux iAVF driver does not do this, it is allowed by the virtchnl
interface.

The current virtchnl code simply sets the per-VSI fields inbetween calls to
ice_vsi_cfg_single_rxq(). This technically works, as these fields are only
ever used when programming the Rx ring, and otherwise not checked again.
However, it is confusing to maintain.

The Rx ring also already has an rx_buf_len field in order to access the
buffer length in the hotpath. It also has extra unused bytes in the ring
structure which we can make use of to store the maximum frame size.

Drop the VSI max_frame and rx_buf_len fields. Add max_frame to the Rx ring,
and slightly re-order rx_buf_len to better fit into the gaps in the
structure layout.

Change the ice_vsi_cfg_frame_size function so that it writes to the ring
fields. Call this function once per ring in ice_vsi_cfg_rxqs(). This is
done over calling it inside the ice_vsi_cfg_rxq(), because
ice_vsi_cfg_rxq() is called in the virtchnl flow where the max_frame and
rx_buf_len have already been configured.

Change the accesses for rx_buf_len and max_frame to all point to the ring
structure. This has the added benefit that ice_vsi_cfg_rxq() no longer has
the surprise side effect of updating ring->rx_buf_len based on the VSI
field.

Update the virtchnl ice_vc_cfg_qs_msg() function to set the ring values
directly, and drop references to the removed VSI fields.

This now makes the VF logic clear, as the ring fields are obviously
per-queue. This reduces the required cognitive load when reasoning about
this logic.

Note that removing the VSI fields does leave a 4 byte gap, but the ice_vsi
structure has many gaps, and its layout is not as critical in the hot path.
The structure may benefit from a more thorough repacking, but no attempt
was made in this change.

Signed-off-by: Jacob Keller <[email protected]>
Tested-by: Rafal Romanowski <[email protected]>
Signed-off-by: Tony Nguyen <[email protected]>

1 files changed, 18 insertions, 16 deletions

diff --git a/drivers/net/ethernet/intel/ice/ice_base.c b/drivers/net/ethernet/intel/ice/ice_base.c
index 4a9a6899fc45..98c3764fed39 100644
--- a/drivers/net/ethernet/intel/ice/ice_base.c
+++ b/drivers/net/ethernet/intel/ice/ice_base.c
@@ -445,7 +445,7 @@ static int ice_setup_rx_ctx(struct ice_rx_ring *ring)
 	/* Max packet size for this queue - must not be set to a larger value
 	 * than 5 x DBUF
 	 */
-	rlan_ctx.rxmax = min_t(u32, vsi->max_frame,
+	rlan_ctx.rxmax = min_t(u32, ring->max_frame,
 			       ICE_MAX_CHAINED_RX_BUFS * ring->rx_buf_len);
 
 	/* Rx queue threshold in units of 64 */
@@ -541,8 +541,6 @@ static int ice_vsi_cfg_rxq(struct ice_rx_ring *ring)
 	u32 num_bufs = ICE_RX_DESC_UNUSED(ring);
 	int err;
 
-	ring->rx_buf_len = ring->vsi->rx_buf_len;
-
 	if (ring->vsi->type == ICE_VSI_PF || ring->vsi->type == ICE_VSI_SF) {
 		if (!xdp_rxq_info_is_reg(&ring->xdp_rxq)) {
 			err = __xdp_rxq_info_reg(&ring->xdp_rxq, ring->netdev,
@@ -641,21 +639,25 @@ int ice_vsi_cfg_single_rxq(struct ice_vsi *vsi, u16 q_idx)
 /**
  * ice_vsi_cfg_frame_size - setup max frame size and Rx buffer length
  * @vsi: VSI
+ * @ring: Rx ring to configure
+ *
+ * Determine the maximum frame size and Rx buffer length to use for a PF VSI.
+ * Set these in the associated Rx ring structure.
  */
-static void ice_vsi_cfg_frame_size(struct ice_vsi *vsi)
+static void ice_vsi_cfg_frame_size(struct ice_vsi *vsi, struct ice_rx_ring *ring)
 {
 	if (!vsi->netdev || test_bit(ICE_FLAG_LEGACY_RX, vsi->back->flags)) {
-		vsi->max_frame = ICE_MAX_FRAME_LEGACY_RX;
-		vsi->rx_buf_len = ICE_RXBUF_1664;
+		ring->max_frame = ICE_MAX_FRAME_LEGACY_RX;
+		ring->rx_buf_len = ICE_RXBUF_1664;
 #if (PAGE_SIZE < 8192)
 	} else if (!ICE_2K_TOO_SMALL_WITH_PADDING &&
 		   (vsi->netdev->mtu <= ETH_DATA_LEN)) {
-		vsi->max_frame = ICE_RXBUF_1536 - NET_IP_ALIGN;
-		vsi->rx_buf_len = ICE_RXBUF_1536 - NET_IP_ALIGN;
+		ring->max_frame = ICE_RXBUF_1536 - NET_IP_ALIGN;
+		ring->rx_buf_len = ICE_RXBUF_1536 - NET_IP_ALIGN;
 #endif
 	} else {
-		vsi->max_frame = ICE_AQ_SET_MAC_FRAME_SIZE_MAX;
-		vsi->rx_buf_len = ICE_RXBUF_3072;
+		ring->max_frame = ICE_AQ_SET_MAC_FRAME_SIZE_MAX;
+		ring->rx_buf_len = ICE_RXBUF_3072;
 	}
 }
 
@@ -670,15 +672,15 @@ int ice_vsi_cfg_rxqs(struct ice_vsi *vsi)
 {
 	u16 i;
 
-	if (vsi->type == ICE_VSI_VF)
-		goto setup_rings;
-
-	ice_vsi_cfg_frame_size(vsi);
-setup_rings:
 	/* set up individual rings */
 	ice_for_each_rxq(vsi, i) {
-		int err = ice_vsi_cfg_rxq(vsi->rx_rings[i]);
+		struct ice_rx_ring *ring = vsi->rx_rings[i];
+		int err;
+
+		if (vsi->type != ICE_VSI_VF)
+			ice_vsi_cfg_frame_size(vsi, ring);
 
+		err = ice_vsi_cfg_rxq(ring);
 		if (err)
 			return err;
 	}