gve: adopt page pool for DQ RDA mode

For DQ queue format in raw DMA addressing(RDA) mode,
implement page pool recycling of buffers by leveraging
a few helper functions.

DQ QPL mode will continue to use the exisiting recycling
logic. This is because in QPL mode, the pages come from a
constant set of pages that the driver pre-allocates and
registers with the device.

Reviewed-by: Praveen Kaligineedi <[email protected]>
Reviewed-by: Shailend Chand <[email protected]>
Reviewed-by: Willem de Bruijn <[email protected]>
Signed-off-by: Harshitha Ramamurthy <[email protected]>
Reviewed-by: Jacob Keller <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: hramamurthy12

drivers/net/ethernet/google/Kconfig

@@ -18,6 +18,7 @@ if NET_VENDOR_GOOGLE
 config GVE
 	tristate "Google Virtual NIC (gVNIC) support"
 	depends on (PCI_MSI && (X86 || CPU_LITTLE_ENDIAN))
+	select PAGE_POOL
 	help
 	  This driver supports Google Virtual NIC (gVNIC)"
 

drivers/net/ethernet/google/gve/gve.h

@@ -13,6 +13,7 @@
 #include <linux/netdevice.h>
 #include <linux/pci.h>
 #include <linux/u64_stats_sync.h>
+#include <net/page_pool/helpers.h>
 #include <net/xdp.h>
 
 #include "gve_desc.h"
@@ -60,6 +61,8 @@
 
 #define GVE_DEFAULT_RX_BUFFER_OFFSET 2048
 
+#define GVE_PAGE_POOL_SIZE_MULTIPLIER 4
+
 #define GVE_FLOW_RULES_CACHE_SIZE \
 	(GVE_ADMINQ_BUFFER_SIZE / sizeof(struct gve_adminq_queried_flow_rule))
 #define GVE_FLOW_RULE_IDS_CACHE_SIZE \
@@ -102,6 +105,7 @@ struct gve_rx_slot_page_info {
 	struct page *page;
 	void *page_address;
 	u32 page_offset; /* offset to write to in page */
+	unsigned int buf_size;
 	int pagecnt_bias; /* expected pagecnt if only the driver has a ref */
 	u16 pad; /* adjustment for rx padding */
 	u8 can_flip; /* tracks if the networking stack is using the page */
@@ -273,6 +277,8 @@ struct gve_rx_ring {
 
 			/* Address info of the buffers for header-split */
 			struct gve_header_buf hdr_bufs;
+
+			struct page_pool *page_pool;
 		} dqo;
 	};
 
@@ -1176,10 +1182,22 @@ struct gve_rx_buf_state_dqo *gve_dequeue_buf_state(struct gve_rx_ring *rx,
 void gve_enqueue_buf_state(struct gve_rx_ring *rx, struct gve_index_list *list,
 			   struct gve_rx_buf_state_dqo *buf_state);
 struct gve_rx_buf_state_dqo *gve_get_recycled_buf_state(struct gve_rx_ring *rx);
-int gve_alloc_page_dqo(struct gve_rx_ring *rx,
-		       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);
+void gve_free_to_page_pool(struct gve_rx_ring *rx,
+			   struct gve_rx_buf_state_dqo *buf_state,
+			   bool allow_direct);
+int gve_alloc_qpl_page_dqo(struct gve_rx_ring *rx,
+			   struct gve_rx_buf_state_dqo *buf_state);
+void gve_free_qpl_page_dqo(struct gve_rx_buf_state_dqo *buf_state);
+void gve_reuse_buffer(struct gve_rx_ring *rx,
+		      struct gve_rx_buf_state_dqo *buf_state);
+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);
+
 /* Reset */
 void gve_schedule_reset(struct gve_priv *priv);
 int gve_reset(struct gve_priv *priv, bool attempt_teardown);

drivers/net/ethernet/google/gve/gve_buffer_mgmt_dqo.c

@@ -12,16 +12,6 @@ int gve_buf_ref_cnt(struct gve_rx_buf_state_dqo *bs)
 	return page_count(bs->page_info.page) - bs->page_info.pagecnt_bias;
 }
 
-void gve_free_page_dqo(struct gve_priv *priv, struct gve_rx_buf_state_dqo *bs,
-		       bool free_page)
-{
-	page_ref_sub(bs->page_info.page, bs->page_info.pagecnt_bias - 1);
-	if (free_page)
-		gve_free_page(&priv->pdev->dev, bs->page_info.page, bs->addr,
-			      DMA_FROM_DEVICE);
-	bs->page_info.page = NULL;
-}
-
 struct gve_rx_buf_state_dqo *gve_alloc_buf_state(struct gve_rx_ring *rx)
 {
 	struct gve_rx_buf_state_dqo *buf_state;
@@ -128,56 +118,28 @@ struct gve_rx_buf_state_dqo *gve_get_recycled_buf_state(struct gve_rx_ring *rx)
 		gve_enqueue_buf_state(rx, &rx->dqo.used_buf_states, buf_state);
 	}
 
-	/* For QPL, we cannot allocate any new buffers and must
-	 * wait for the existing ones to be available.
-	 */
-	if (rx->dqo.qpl)
-		return NULL;
-
-	/* If there are no free buf states discard an entry from
-	 * `used_buf_states` so it can be used.
-	 */
-	if (unlikely(rx->dqo.free_buf_states == -1)) {
-		buf_state = gve_dequeue_buf_state(rx, &rx->dqo.used_buf_states);
-		if (gve_buf_ref_cnt(buf_state) == 0)
-			return buf_state;
-
-		gve_free_page_dqo(rx->gve, buf_state, true);
-		gve_free_buf_state(rx, buf_state);
-	}
-
 	return NULL;
 }
 
-int gve_alloc_page_dqo(struct gve_rx_ring *rx,
-		       struct gve_rx_buf_state_dqo *buf_state)
+int gve_alloc_qpl_page_dqo(struct gve_rx_ring *rx,
+			   struct gve_rx_buf_state_dqo *buf_state)
 {
 	struct gve_priv *priv = rx->gve;
 	u32 idx;
 
-	if (!rx->dqo.qpl) {
-		int err;
-
-		err = gve_alloc_page(priv, &priv->pdev->dev,
-				     &buf_state->page_info.page,
-				     &buf_state->addr,
-				     DMA_FROM_DEVICE, GFP_ATOMIC);
-		if (err)
-			return err;
-	} else {
-		idx = rx->dqo.next_qpl_page_idx;
-		if (idx >= gve_get_rx_pages_per_qpl_dqo(priv->rx_desc_cnt)) {
-			net_err_ratelimited("%s: Out of QPL pages\n",
-					    priv->dev->name);
-			return -ENOMEM;
-		}
-		buf_state->page_info.page = rx->dqo.qpl->pages[idx];
-		buf_state->addr = rx->dqo.qpl->page_buses[idx];
-		rx->dqo.next_qpl_page_idx++;
+	idx = rx->dqo.next_qpl_page_idx;
+	if (idx >= gve_get_rx_pages_per_qpl_dqo(priv->rx_desc_cnt)) {
+		net_err_ratelimited("%s: Out of QPL pages\n",
+				    priv->dev->name);
+		return -ENOMEM;
 	}
+	buf_state->page_info.page = rx->dqo.qpl->pages[idx];
+	buf_state->addr = rx->dqo.qpl->page_buses[idx];
+	rx->dqo.next_qpl_page_idx++;
 	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 = priv->data_buffer_size_dqo;
 	buf_state->last_single_ref_offset = 0;
 
 	/* The page already has 1 ref. */
@@ -187,6 +149,16 @@ int gve_alloc_page_dqo(struct gve_rx_ring *rx,
 	return 0;
 }
 
+void gve_free_qpl_page_dqo(struct gve_rx_buf_state_dqo *buf_state)
+{
+	if (!buf_state->page_info.page)
+		return;
+
+	page_ref_sub(buf_state->page_info.page,
+		     buf_state->page_info.pagecnt_bias - 1);
+	buf_state->page_info.page = NULL;
+}
+
 void gve_try_recycle_buf(struct gve_priv *priv, struct gve_rx_ring *rx,
 			 struct gve_rx_buf_state_dqo *buf_state)
 {
@@ -228,3 +200,113 @@ void gve_try_recycle_buf(struct gve_priv *priv, struct gve_rx_ring *rx,
 	gve_enqueue_buf_state(rx, &rx->dqo.used_buf_states, buf_state);
 	rx->dqo.used_buf_states_cnt++;
 }
+
+void gve_free_to_page_pool(struct gve_rx_ring *rx,
+			   struct gve_rx_buf_state_dqo *buf_state,
+			   bool allow_direct)
+{
+	struct page *page = buf_state->page_info.page;
+
+	if (!page)
+		return;
+
+	page_pool_put_page(page->pp, page, buf_state->page_info.buf_size,
+			   allow_direct);
+	buf_state->page_info.page = NULL;
+}
+
+static int gve_alloc_from_page_pool(struct gve_rx_ring *rx,
+				    struct gve_rx_buf_state_dqo *buf_state)
+{
+	struct gve_priv *priv = rx->gve;
+	struct page *page;
+
+	buf_state->page_info.buf_size = priv->data_buffer_size_dqo;
+	page = page_pool_alloc(rx->dqo.page_pool,
+			       &buf_state->page_info.page_offset,
+			       &buf_state->page_info.buf_size, GFP_ATOMIC);
+
+	if (!page)
+		return -ENOMEM;
+
+	buf_state->page_info.page = page;
+	buf_state->page_info.page_address = page_address(page);
+	buf_state->addr = page_pool_get_dma_addr(page);
+
+	return 0;
+}
+
+struct page_pool *gve_rx_create_page_pool(struct gve_priv *priv,
+					  struct gve_rx_ring *rx)
+{
+	u32 ntfy_id = gve_rx_idx_to_ntfy(priv, rx->q_num);
+	struct page_pool_params pp = {
+		.flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV,
+		.order = 0,
+		.pool_size = GVE_PAGE_POOL_SIZE_MULTIPLIER * priv->rx_desc_cnt,
+		.dev = &priv->pdev->dev,
+		.netdev = priv->dev,
+		.napi = &priv->ntfy_blocks[ntfy_id].napi,
+		.max_len = PAGE_SIZE,
+		.dma_dir = DMA_FROM_DEVICE,
+	};
+
+	return page_pool_create(&pp);
+}
+
+void gve_free_buffer(struct gve_rx_ring *rx,
+		     struct gve_rx_buf_state_dqo *buf_state)
+{
+	if (rx->dqo.page_pool) {
+		gve_free_to_page_pool(rx, buf_state, true);
+		gve_free_buf_state(rx, buf_state);
+	} else {
+		gve_enqueue_buf_state(rx, &rx->dqo.recycled_buf_states,
+				      buf_state);
+	}
+}
+
+void gve_reuse_buffer(struct gve_rx_ring *rx,
+		      struct gve_rx_buf_state_dqo *buf_state)
+{
+	if (rx->dqo.page_pool) {
+		buf_state->page_info.page = NULL;
+		gve_free_buf_state(rx, buf_state);
+	} else {
+		gve_dec_pagecnt_bias(&buf_state->page_info);
+		gve_try_recycle_buf(rx->gve, rx, buf_state);
+	}
+}
+
+int gve_alloc_buffer(struct gve_rx_ring *rx, struct gve_rx_desc_dqo *desc)
+{
+	struct gve_rx_buf_state_dqo *buf_state;
+
+	if (rx->dqo.page_pool) {
+		buf_state = gve_alloc_buf_state(rx);
+		if (WARN_ON_ONCE(!buf_state))
+			return -ENOMEM;
+
+		if (gve_alloc_from_page_pool(rx, buf_state))
+			goto free_buf_state;
+	} else {
+		buf_state = gve_get_recycled_buf_state(rx);
+		if (unlikely(!buf_state)) {
+			buf_state = gve_alloc_buf_state(rx);
+			if (unlikely(!buf_state))
+				return -ENOMEM;
+
+			if (unlikely(gve_alloc_qpl_page_dqo(rx, buf_state)))
+				goto free_buf_state;
+		}
+	}
+	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);
+
+	return 0;
+
+free_buf_state:
+	gve_free_buf_state(rx, buf_state);
+	return -ENOMEM;
+}