diff mbox series

[net-next,5/6] gve: update XDP allocation path support RX buffer posting

Message ID 20250321002910.1343422-6-hramamurthy@google.com (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series Basic XDP Support for DQO RDA Queue Format | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 16 of 16 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 193 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest warning net-next-2025-03-21--18-00 (tests: 896)

Commit Message

Harshitha Ramamurthy March 21, 2025, 12:29 a.m. UTC 
From: Joshua Washington <joshwash@google.com>

In order to support installing an XDP program on DQ, RX buffers need to
be reposted using 4K buffers, which is larger than the default packet
buffer size of 2K. This is needed to accommodate the extra head and tail
that accompanies the data portion of an XDP buffer. Continuing to use 2K
buffers would mean that the packet buffer size for the NIC would have to
be restricted to 2048 - 320 - 256 = 1472B. However, this is problematic
for two reasons: first, 1472 is not a packet buffer size accepted by
GVE; second, at least 1474B of buffer space is needed to accommodate an
MTU of 1460, which is the default on GCP. As such, we allocate 4K
buffers, and post a 2K section of those 4K buffers (offset relative to
the XDP headroom) to the NIC for DMA to avoid a potential extra copy.
Because the GQ-QPL datapath requires copies regardless, this change was
not needed to support XDP in that case.

To capture this subtlety, a new field, packet_buffer_truesize, has been
added to the rx ring struct to represent size of the allocated buffer,
while packet_buffer_size has been left to represent the portion of the
buffer posted to the NIC.

Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Praveen Kaligineedi <pkaligineedi@google.com>
Signed-off-by: Joshua Washington <joshwash@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
---
 drivers/net/ethernet/google/gve/gve.h         | 12 ++++++++--
 .../ethernet/google/gve/gve_buffer_mgmt_dqo.c | 17 +++++++++-----
 drivers/net/ethernet/google/gve/gve_main.c    | 19 +++++++++++++---
 drivers/net/ethernet/google/gve/gve_rx_dqo.c  | 22 ++++++++++++++-----
 4 files changed, 53 insertions(+), 17 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/google/gve/gve.h b/drivers/net/ethernet/google/gve/gve.h
index 9895541eddae..2fab38c8ee78 100644
--- a/drivers/net/ethernet/google/gve/gve.h
+++ b/drivers/net/ethernet/google/gve/gve.h
@@ -59,6 +59,8 @@ 
 
 #define GVE_MAX_RX_BUFFER_SIZE 4096
 
+#define GVE_XDP_RX_BUFFER_SIZE_DQO 4096
+
 #define GVE_DEFAULT_RX_BUFFER_OFFSET 2048
 
 #define GVE_PAGE_POOL_SIZE_MULTIPLIER 4
@@ -227,7 +229,11 @@  struct gve_rx_cnts {
 /* Contains datapath state used to represent an RX queue. */
 struct gve_rx_ring {
 	struct gve_priv *gve;
-	u16 packet_buffer_size;
+
+	u16 packet_buffer_size;		/* Size of buffer posted to NIC */
+	u16 packet_buffer_truesize;	/* Total size of RX buffer */
+	u16 rx_headroom;
+
 	union {
 		/* GQI fields */
 		struct {
@@ -688,6 +694,7 @@  struct gve_rx_alloc_rings_cfg {
 	bool raw_addressing;
 	bool enable_header_split;
 	bool reset_rss;
+	bool xdp;
 
 	/* Allocated resources are returned here */
 	struct gve_rx_ring *rx;
@@ -1218,7 +1225,8 @@  void gve_free_buffer(struct gve_rx_ring *rx,
 		     struct gve_rx_buf_state_dqo *buf_state);
 int gve_alloc_buffer(struct gve_rx_ring *rx, struct gve_rx_desc_dqo *desc);
 struct page_pool *gve_rx_create_page_pool(struct gve_priv *priv,
-					  struct gve_rx_ring *rx);
+					  struct gve_rx_ring *rx,
+					  bool xdp);
 
 /* Reset */
 void gve_schedule_reset(struct gve_priv *priv);
diff --git a/drivers/net/ethernet/google/gve/gve_buffer_mgmt_dqo.c b/drivers/net/ethernet/google/gve/gve_buffer_mgmt_dqo.c
index f9824664d04c..a71883e1d920 100644
--- a/drivers/net/ethernet/google/gve/gve_buffer_mgmt_dqo.c
+++ b/drivers/net/ethernet/google/gve/gve_buffer_mgmt_dqo.c
@@ -139,7 +139,8 @@  int gve_alloc_qpl_page_dqo(struct gve_rx_ring *rx,
 	buf_state->page_info.page_offset = 0;
 	buf_state->page_info.page_address =
 		page_address(buf_state->page_info.page);
-	buf_state->page_info.buf_size = rx->packet_buffer_size;
+	buf_state->page_info.buf_size = rx->packet_buffer_truesize;
+	buf_state->page_info.pad = rx->rx_headroom;
 	buf_state->last_single_ref_offset = 0;
 
 	/* The page already has 1 ref. */
@@ -162,7 +163,7 @@  void gve_free_qpl_page_dqo(struct gve_rx_buf_state_dqo *buf_state)
 void gve_try_recycle_buf(struct gve_priv *priv, struct gve_rx_ring *rx,
 			 struct gve_rx_buf_state_dqo *buf_state)
 {
-	const u16 data_buffer_size = rx->packet_buffer_size;
+	const u16 data_buffer_size = rx->packet_buffer_truesize;
 	int pagecount;
 
 	/* Can't reuse if we only fit one buffer per page */
@@ -219,7 +220,7 @@  static int gve_alloc_from_page_pool(struct gve_rx_ring *rx,
 {
 	netmem_ref netmem;
 
-	buf_state->page_info.buf_size = rx->packet_buffer_size;
+	buf_state->page_info.buf_size = rx->packet_buffer_truesize;
 	netmem = page_pool_alloc_netmem(rx->dqo.page_pool,
 					&buf_state->page_info.page_offset,
 					&buf_state->page_info.buf_size,
@@ -231,12 +232,14 @@  static int gve_alloc_from_page_pool(struct gve_rx_ring *rx,
 	buf_state->page_info.netmem = netmem;
 	buf_state->page_info.page_address = netmem_address(netmem);
 	buf_state->addr = page_pool_get_dma_addr_netmem(netmem);
+	buf_state->page_info.pad = rx->dqo.page_pool->p.offset;
 
 	return 0;
 }
 
 struct page_pool *gve_rx_create_page_pool(struct gve_priv *priv,
-					  struct gve_rx_ring *rx)
+					  struct gve_rx_ring *rx,
+					  bool xdp)
 {
 	u32 ntfy_id = gve_rx_idx_to_ntfy(priv, rx->q_num);
 	struct page_pool_params pp = {
@@ -247,7 +250,8 @@  struct page_pool *gve_rx_create_page_pool(struct gve_priv *priv,
 		.netdev = priv->dev,
 		.napi = &priv->ntfy_blocks[ntfy_id].napi,
 		.max_len = PAGE_SIZE,
-		.dma_dir = DMA_FROM_DEVICE,
+		.dma_dir = xdp ? DMA_BIDIRECTIONAL : DMA_FROM_DEVICE,
+		.offset = xdp ? XDP_PACKET_HEADROOM : 0,
 	};
 
 	return page_pool_create(&pp);
@@ -301,7 +305,8 @@  int gve_alloc_buffer(struct gve_rx_ring *rx, struct gve_rx_desc_dqo *desc)
 	}
 	desc->buf_id = cpu_to_le16(buf_state - rx->dqo.buf_states);
 	desc->buf_addr = cpu_to_le64(buf_state->addr +
-				     buf_state->page_info.page_offset);
+				     buf_state->page_info.page_offset +
+				     buf_state->page_info.pad);
 
 	return 0;
 
diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index 20aabbe0e518..cb2f9978f45e 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -1149,8 +1149,14 @@  static int gve_reg_xdp_info(struct gve_priv *priv, struct net_device *dev)
 				       napi->napi_id);
 		if (err)
 			goto err;
-		err = xdp_rxq_info_reg_mem_model(&rx->xdp_rxq,
-						 MEM_TYPE_PAGE_SHARED, NULL);
+		if (gve_is_qpl(priv))
+			err = xdp_rxq_info_reg_mem_model(&rx->xdp_rxq,
+							 MEM_TYPE_PAGE_SHARED,
+							 NULL);
+		else
+			err = xdp_rxq_info_reg_mem_model(&rx->xdp_rxq,
+							 MEM_TYPE_PAGE_POOL,
+							 rx->dqo.page_pool);
 		if (err)
 			goto err;
 		rx->xsk_pool = xsk_get_pool_from_qid(dev, i);
@@ -1226,6 +1232,7 @@  static void gve_rx_get_curr_alloc_cfg(struct gve_priv *priv,
 	cfg->ring_size = priv->rx_desc_cnt;
 	cfg->packet_buffer_size = priv->rx_cfg.packet_buffer_size;
 	cfg->rx = priv->rx;
+	cfg->xdp = !!cfg->qcfg_tx->num_xdp_queues;
 }
 
 void gve_get_curr_alloc_cfgs(struct gve_priv *priv,
@@ -1461,6 +1468,7 @@  static int gve_configure_rings_xdp(struct gve_priv *priv,
 	gve_get_curr_alloc_cfgs(priv, &tx_alloc_cfg, &rx_alloc_cfg);
 	tx_alloc_cfg.num_xdp_rings = num_xdp_rings;
 
+	rx_alloc_cfg.xdp = !!num_xdp_rings;
 	return gve_adjust_config(priv, &tx_alloc_cfg, &rx_alloc_cfg);
 }
 
@@ -1629,6 +1637,7 @@  static int gve_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)
 static int verify_xdp_configuration(struct net_device *dev)
 {
 	struct gve_priv *priv = netdev_priv(dev);
+	u16 max_xdp_mtu;
 
 	if (dev->features & NETIF_F_LRO) {
 		netdev_warn(dev, "XDP is not supported when LRO is on.\n");
@@ -1641,7 +1650,11 @@  static int verify_xdp_configuration(struct net_device *dev)
 		return -EOPNOTSUPP;
 	}
 
-	if (dev->mtu > GVE_DEFAULT_RX_BUFFER_SIZE - sizeof(struct ethhdr) - GVE_RX_PAD) {
+	max_xdp_mtu = priv->rx_cfg.packet_buffer_size - sizeof(struct ethhdr);
+	if (priv->queue_format == GVE_GQI_QPL_FORMAT)
+		max_xdp_mtu -= GVE_RX_PAD;
+
+	if (dev->mtu > max_xdp_mtu) {
 		netdev_warn(dev, "XDP is not supported for mtu %d.\n",
 			    dev->mtu);
 		return -EOPNOTSUPP;
diff --git a/drivers/net/ethernet/google/gve/gve_rx_dqo.c b/drivers/net/ethernet/google/gve/gve_rx_dqo.c
index 5fbcf93a54e0..2edf3c632cbd 100644
--- a/drivers/net/ethernet/google/gve/gve_rx_dqo.c
+++ b/drivers/net/ethernet/google/gve/gve_rx_dqo.c
@@ -225,6 +225,14 @@  int gve_rx_alloc_ring_dqo(struct gve_priv *priv,
 	rx->q_num = idx;
 	rx->packet_buffer_size = cfg->packet_buffer_size;
 
+	if (cfg->xdp) {
+		rx->packet_buffer_truesize = GVE_XDP_RX_BUFFER_SIZE_DQO;
+		rx->rx_headroom = XDP_PACKET_HEADROOM;
+	} else {
+		rx->packet_buffer_truesize = rx->packet_buffer_size;
+		rx->rx_headroom = 0;
+	}
+
 	rx->dqo.num_buf_states = cfg->raw_addressing ? buffer_queue_slots :
 		gve_get_rx_pages_per_qpl_dqo(cfg->ring_size);
 	rx->dqo.buf_states = kvcalloc(rx->dqo.num_buf_states,
@@ -254,7 +262,7 @@  int gve_rx_alloc_ring_dqo(struct gve_priv *priv,
 		goto err;
 
 	if (cfg->raw_addressing) {
-		pool = gve_rx_create_page_pool(priv, rx);
+		pool = gve_rx_create_page_pool(priv, rx, cfg->xdp);
 		if (IS_ERR(pool))
 			goto err;
 
@@ -484,14 +492,15 @@  static void gve_skb_add_rx_frag(struct gve_rx_ring *rx,
 	if (rx->dqo.page_pool) {
 		skb_add_rx_frag_netmem(rx->ctx.skb_tail, num_frags,
 				       buf_state->page_info.netmem,
-				       buf_state->page_info.page_offset,
-				       buf_len,
+				       buf_state->page_info.page_offset +
+				       buf_state->page_info.pad, buf_len,
 				       buf_state->page_info.buf_size);
 	} else {
 		skb_add_rx_frag(rx->ctx.skb_tail, num_frags,
 				buf_state->page_info.page,
-				buf_state->page_info.page_offset,
-				buf_len, buf_state->page_info.buf_size);
+				buf_state->page_info.page_offset +
+				buf_state->page_info.pad, buf_len,
+				buf_state->page_info.buf_size);
 	}
 }
 
@@ -611,7 +620,8 @@  static int gve_rx_dqo(struct napi_struct *napi, struct gve_rx_ring *rx,
 
 	/* Sync the portion of dma buffer for CPU to read. */
 	dma_sync_single_range_for_cpu(&priv->pdev->dev, buf_state->addr,
-				      buf_state->page_info.page_offset,
+				      buf_state->page_info.page_offset +
+				      buf_state->page_info.pad,
 				      buf_len, DMA_FROM_DEVICE);
 
 	/* Append to current skb if one exists. */