diff options
Diffstat (limited to 'drivers/net/ethernet/google/gve/gve_buffer_mgmt_dqo.c')
| -rw-r--r-- | drivers/net/ethernet/google/gve/gve_buffer_mgmt_dqo.c | 230 |
1 files changed, 230 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..8e50f0e4bb2e --- /dev/null +++ b/drivers/net/ethernet/google/gve/gve_buffer_mgmt_dqo.c @@ -0,0 +1,230 @@ +// 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; +} + +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; + 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); + } + + /* 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) +{ + 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++; + } + buf_state->page_info.page_offset = 0; + buf_state->page_info.page_address = + page_address(buf_state->page_info.page); + 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_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++; +} |