1 files changed, 311 insertions, 0 deletions
diff --git a/drivers/net/ethernet/google/gve/gve_buffer_mgmt_dqo.c b/drivers/net/ethernet/google/gve/gve_buffer_mgmt_dqo.c
new file mode 100644
index 000000000000..403f0f335ba6
--- /dev/null
+++ b/drivers/net/ethernet/google/gve/gve_buffer_mgmt_dqo.c
@@ -0,0 +1,311 @@
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/* Google virtual Ethernet (gve) driver
+ *
+ * Copyright (C) 2015-2024 Google, Inc.
+ */
+
+#include "gve.h"
+#include "gve_utils.h"
+
+int gve_buf_ref_cnt(struct gve_rx_buf_state_dqo *bs)
+{
+	return page_count(bs->page_info.page) - bs->page_info.pagecnt_bias;
+}
+
+struct gve_rx_buf_state_dqo *gve_alloc_buf_state(struct gve_rx_ring *rx)
+{
+	struct gve_rx_buf_state_dqo *buf_state;
+	s16 buffer_id;
+
+	buffer_id = rx->dqo.free_buf_states;
+	if (unlikely(buffer_id == -1))
+		return NULL;
+
+	buf_state = &rx->dqo.buf_states[buffer_id];
+
+	/* Remove buf_state from free list */
+	rx->dqo.free_buf_states = buf_state->next;
+
+	/* Point buf_state to itself to mark it as allocated */
+	buf_state->next = buffer_id;
+
+	return buf_state;
+}
+
+bool gve_buf_state_is_allocated(struct gve_rx_ring *rx,
+				struct gve_rx_buf_state_dqo *buf_state)
+{
+	s16 buffer_id = buf_state - rx->dqo.buf_states;
+
+	return buf_state->next == buffer_id;
+}
+
+void gve_free_buf_state(struct gve_rx_ring *rx,
+			struct gve_rx_buf_state_dqo *buf_state)
+{
+	s16 buffer_id = buf_state - rx->dqo.buf_states;
+
+	buf_state->next = rx->dqo.free_buf_states;
+	rx->dqo.free_buf_states = buffer_id;
+}
+
+struct gve_rx_buf_state_dqo *gve_dequeue_buf_state(struct gve_rx_ring *rx,
+						   struct gve_index_list *list)
+{
+	struct gve_rx_buf_state_dqo *buf_state;
+	s16 buffer_id;
+
+	buffer_id = list->head;
+	if (unlikely(buffer_id == -1))
+		return NULL;
+
+	buf_state = &rx->dqo.buf_states[buffer_id];
+
+	/* Remove buf_state from list */
+	list->head = buf_state->next;
+	if (buf_state->next == -1)
+		list->tail = -1;
+
+	/* Point buf_state to itself to mark it as allocated */
+	buf_state->next = buffer_id;
+
+	return buf_state;
+}
+
+void gve_enqueue_buf_state(struct gve_rx_ring *rx, struct gve_index_list *list,
+			   struct gve_rx_buf_state_dqo *buf_state)
+{
+	s16 buffer_id = buf_state - rx->dqo.buf_states;
+
+	buf_state->next = -1;
+
+	if (list->head == -1) {
+		list->head = buffer_id;
+		list->tail = buffer_id;
+	} else {
+		int tail = list->tail;
+
+		rx->dqo.buf_states[tail].next = buffer_id;
+		list->tail = buffer_id;
+	}
+}
+
+struct gve_rx_buf_state_dqo *gve_get_recycled_buf_state(struct gve_rx_ring *rx)
+{
+	struct gve_rx_buf_state_dqo *buf_state;
+	int i;
+
+	/* Recycled buf states are immediately usable. */
+	buf_state = gve_dequeue_buf_state(rx, &rx->dqo.recycled_buf_states);
+	if (likely(buf_state))
+		return buf_state;
+
+	if (unlikely(rx->dqo.used_buf_states.head == -1))
+		return NULL;
+
+	/* Used buf states are only usable when ref count reaches 0, which means
+	 * no SKBs refer to them.
+	 *
+	 * Search a limited number before giving up.
+	 */
+	for (i = 0; i < 5; i++) {
+		buf_state = gve_dequeue_buf_state(rx, &rx->dqo.used_buf_states);
+		if (gve_buf_ref_cnt(buf_state) == 0) {
+			rx->dqo.used_buf_states_cnt--;
+			return buf_state;
+		}
+
+		gve_enqueue_buf_state(rx, &rx->dqo.used_buf_states, buf_state);
+	}
+
+	return NULL;
+}
+
+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;
+
+	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. */
+	page_ref_add(buf_state->page_info.page, INT_MAX - 1);
+	buf_state->page_info.pagecnt_bias = INT_MAX;
+
+	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)
+{
+	const u16 data_buffer_size = priv->data_buffer_size_dqo;
+	int pagecount;
+
+	/* Can't reuse if we only fit one buffer per page */
+	if (data_buffer_size * 2 > PAGE_SIZE)
+		goto mark_used;
+
+	pagecount = gve_buf_ref_cnt(buf_state);
+
+	/* Record the offset when we have a single remaining reference.
+	 *
+	 * When this happens, we know all of the other offsets of the page are
+	 * usable.
+	 */
+	if (pagecount == 1) {
+		buf_state->last_single_ref_offset =
+			buf_state->page_info.page_offset;
+	}
+
+	/* Use the next buffer sized chunk in the page. */
+	buf_state->page_info.page_offset += data_buffer_size;
+	buf_state->page_info.page_offset &= (PAGE_SIZE - 1);
+
+	/* If we wrap around to the same offset without ever dropping to 1
+	 * reference, then we don't know if this offset was ever freed.
+	 */
+	if (buf_state->page_info.page_offset ==
+	    buf_state->last_single_ref_offset) {
+		goto mark_used;
+	}
+
+	gve_enqueue_buf_state(rx, &rx->dqo.recycled_buf_states, buf_state);
+	return;
+
+mark_used:
+	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_full_page(page->pp, page, 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;
+}