gve: Add header split data path

Add header buffers and ethtool support to enable header split via the
tcp-data-split flag in ethtool's ringparam config. A coherent dma memory
is allocated for the header buffers. There is one header buffer per ring
entry by calculating the offset to the header-buffers starting address.
The header buffer is always copied directly into the skb and payload is
always added as frags. When there is a header buffer overflow or the
header length is 0, the driver places the whole unsplit packet in frags.

When toggling header split, the driver will call gve_adjust_config to
set its queues appropriately. If header split is enabled by the user and
the max packet buffer size is no less than 4KB, driver will set the
packet buffer size as 4KB to support TCP_ZEROCOPY_RECEIVE. Otherwise the
driver will use the default 2KB as the packet buffer size.

`ethtool -G <dev> tcp-data-split on/off` is the command to toggle header
split.
`ethtool -g <dev>` will show the status of header split with the field
of `tcp-data-split`.

Co-developed-by: Ziwei Xiao <ziweixiao@google.com>
Signed-off-by: Ziwei Xiao <ziweixiao@google.com>
Signed-off-by: Jeroen de Borst <jeroendb@google.com>
Reviewed-by: Praveen Kaligineedi <pkaligineedi@google.com>
Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/net/ethernet/google/gve/gve.h b/drivers/net/ethernet/google/gve/gve.h
index 5305404516fc..5f02b87d7fea 100644
--- a/drivers/net/ethernet/google/gve/gve.h
+++ b/drivers/net/ethernet/google/gve/gve.h
@@ -9,6 +9,7 @@
 
 #include <linux/dma-mapping.h>
 #include <linux/dmapool.h>
+#include <linux/ethtool_netlink.h>
 #include <linux/netdevice.h>
 #include <linux/pci.h>
 #include <linux/u64_stats_sync.h>
@@ -154,6 +155,11 @@ struct gve_rx_compl_queue_dqo {
 	u32 mask; /* Mask for indices to the size of the ring */
 };
 
+struct gve_header_buf {
+	u8 *data;
+	dma_addr_t addr;
+};
+
 /* Stores state for tracking buffers posted to HW */
 struct gve_rx_buf_state_dqo {
 	/* The page posted to HW. */
@@ -256,6 +262,9 @@ struct gve_rx_ring {
 
 			/* track number of used buffers */
 			u16 used_buf_states_cnt;
+
+			/* Address info of the buffers for header-split */
+			struct gve_header_buf hdr_bufs;
 		} dqo;
 	};
 
@@ -668,6 +677,7 @@ struct gve_rx_alloc_rings_cfg {
 	struct gve_qpl_config *qpl_cfg;
 
 	u16 ring_size;
+	u16 packet_buffer_size;
 	bool raw_addressing;
 	bool enable_header_split;
 
@@ -792,6 +802,7 @@ struct gve_priv {
 	u32 rx_coalesce_usecs;
 
 	u16 header_buf_size; /* device configured, header-split supported if non-zero */
+	bool header_split_enabled; /* True if the header split is enabled by the user */
 };
 
 enum gve_service_task_flags_bit {
@@ -1129,6 +1140,9 @@ void gve_rx_free_rings_gqi(struct gve_priv *priv,
 			   struct gve_rx_alloc_rings_cfg *cfg);
 void gve_rx_start_ring_gqi(struct gve_priv *priv, int idx);
 void gve_rx_stop_ring_gqi(struct gve_priv *priv, int idx);
+u16 gve_get_pkt_buf_size(const struct gve_priv *priv, bool enable_hplit);
+bool gve_header_split_supported(const struct gve_priv *priv);
+int gve_set_hsplit_config(struct gve_priv *priv, u8 tcp_data_split);
 /* Reset */
 void gve_schedule_reset(struct gve_priv *priv);
 int gve_reset(struct gve_priv *priv, bool attempt_teardown);