xref: /openbmc/linux/drivers/net/ethernet/sfc/rx_common.c (revision 3d95b884)

// SPDX-License-Identifier: GPL-2.0-only
/****************************************************************************
 * Driver for Solarflare network controllers and boards
 * Copyright 2018 Solarflare Communications Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation, incorporated herein by reference.
 */

#include "net_driver.h"
#include <linux/module.h>
#include <linux/iommu.h>
#include "efx.h"
#include "nic.h"
#include "rx_common.h"

/* This is the percentage fill level below which new RX descriptors
 * will be added to the RX descriptor ring.
 */
static unsigned int rx_refill_threshold;
module_param(rx_refill_threshold, uint, 0444);
MODULE_PARM_DESC(rx_refill_threshold,
		 "RX descriptor ring refill threshold (%)");

/* Number of RX buffers to recycle pages for.  When creating the RX page recycle
 * ring, this number is divided by the number of buffers per page to calculate
 * the number of pages to store in the RX page recycle ring.
 */
#define EFX_RECYCLE_RING_SIZE_IOMMU 4096
#define EFX_RECYCLE_RING_SIZE_NOIOMMU (2 * EFX_RX_PREFERRED_BATCH)

/* RX maximum head room required.
 *
 * This must be at least 1 to prevent overflow, plus one packet-worth
 * to allow pipelined receives.
 */
#define EFX_RXD_HEAD_ROOM (1 + EFX_RX_MAX_FRAGS)

/* Check the RX page recycle ring for a page that can be reused. */
static struct page *efx_reuse_page(struct efx_rx_queue *rx_queue)
{
	struct efx_nic *efx = rx_queue->efx;
	struct efx_rx_page_state *state;
	unsigned int index;
	struct page *page;

	index = rx_queue->page_remove & rx_queue->page_ptr_mask;
	page = rx_queue->page_ring[index];
	if (page == NULL)
		return NULL;

	rx_queue->page_ring[index] = NULL;
	/* page_remove cannot exceed page_add. */
	if (rx_queue->page_remove != rx_queue->page_add)
		++rx_queue->page_remove;

	/* If page_count is 1 then we hold the only reference to this page. */
	if (page_count(page) == 1) {
		++rx_queue->page_recycle_count;
		return page;
	} else {
		state = page_address(page);
		dma_unmap_page(&efx->pci_dev->dev, state->dma_addr,
			       PAGE_SIZE << efx->rx_buffer_order,
			       DMA_FROM_DEVICE);
		put_page(page);
		++rx_queue->page_recycle_failed;
	}

	return NULL;
}

/* Attempt to recycle the page if there is an RX recycle ring; the page can
 * only be added if this is the final RX buffer, to prevent pages being used in
 * the descriptor ring and appearing in the recycle ring simultaneously.
 */
static void efx_recycle_rx_page(struct efx_channel *channel,
				struct efx_rx_buffer *rx_buf)
{
	struct efx_rx_queue *rx_queue = efx_channel_get_rx_queue(channel);
	struct efx_nic *efx = rx_queue->efx;
	struct page *page = rx_buf->page;
	unsigned int index;

	/* Only recycle the page after processing the final buffer. */
	if (!(rx_buf->flags & EFX_RX_BUF_LAST_IN_PAGE))
		return;

	index = rx_queue->page_add & rx_queue->page_ptr_mask;
	if (rx_queue->page_ring[index] == NULL) {
		unsigned int read_index = rx_queue->page_remove &
			rx_queue->page_ptr_mask;

		/* The next slot in the recycle ring is available, but
		 * increment page_remove if the read pointer currently
		 * points here.
		 */
		if (read_index == index)
			++rx_queue->page_remove;
		rx_queue->page_ring[index] = page;
		++rx_queue->page_add;
		return;
	}
	++rx_queue->page_recycle_full;
	efx_unmap_rx_buffer(efx, rx_buf);
	put_page(rx_buf->page);
}

/* Recycle the pages that are used by buffers that have just been received. */
void efx_recycle_rx_pages(struct efx_channel *channel,
			  struct efx_rx_buffer *rx_buf,
			  unsigned int n_frags)
{
	struct efx_rx_queue *rx_queue = efx_channel_get_rx_queue(channel);

	do {
		efx_recycle_rx_page(channel, rx_buf);
		rx_buf = efx_rx_buf_next(rx_queue, rx_buf);
	} while (--n_frags);
}

void efx_discard_rx_packet(struct efx_channel *channel,
			   struct efx_rx_buffer *rx_buf,
			   unsigned int n_frags)
{
	struct efx_rx_queue *rx_queue = efx_channel_get_rx_queue(channel);

	efx_recycle_rx_pages(channel, rx_buf, n_frags);

	efx_free_rx_buffers(rx_queue, rx_buf, n_frags);
}

static void efx_init_rx_recycle_ring(struct efx_rx_queue *rx_queue)
{
	unsigned int bufs_in_recycle_ring, page_ring_size;
	struct efx_nic *efx = rx_queue->efx;

	/* Set the RX recycle ring size */
#ifdef CONFIG_PPC64
	bufs_in_recycle_ring = EFX_RECYCLE_RING_SIZE_IOMMU;
#else
	if (iommu_present(&pci_bus_type))
		bufs_in_recycle_ring = EFX_RECYCLE_RING_SIZE_IOMMU;
	else
		bufs_in_recycle_ring = EFX_RECYCLE_RING_SIZE_NOIOMMU;
#endif /* CONFIG_PPC64 */

	page_ring_size = roundup_pow_of_two(bufs_in_recycle_ring /
					    efx->rx_bufs_per_page);
	rx_queue->page_ring = kcalloc(page_ring_size,
				      sizeof(*rx_queue->page_ring), GFP_KERNEL);
	rx_queue->page_ptr_mask = page_ring_size - 1;
}

static void efx_fini_rx_recycle_ring(struct efx_rx_queue *rx_queue)
{
	struct efx_nic *efx = rx_queue->efx;
	int i;

	/* Unmap and release the pages in the recycle ring. Remove the ring. */
	for (i = 0; i <= rx_queue->page_ptr_mask; i++) {
		struct page *page = rx_queue->page_ring[i];
		struct efx_rx_page_state *state;

		if (page == NULL)
			continue;

		state = page_address(page);
		dma_unmap_page(&efx->pci_dev->dev, state->dma_addr,
			       PAGE_SIZE << efx->rx_buffer_order,
			       DMA_FROM_DEVICE);
		put_page(page);
	}
	kfree(rx_queue->page_ring);
	rx_queue->page_ring = NULL;
}

static void efx_fini_rx_buffer(struct efx_rx_queue *rx_queue,
			       struct efx_rx_buffer *rx_buf)
{
	/* Release the page reference we hold for the buffer. */
	if (rx_buf->page)
		put_page(rx_buf->page);

	/* If this is the last buffer in a page, unmap and free it. */
	if (rx_buf->flags & EFX_RX_BUF_LAST_IN_PAGE) {
		efx_unmap_rx_buffer(rx_queue->efx, rx_buf);
		efx_free_rx_buffers(rx_queue, rx_buf, 1);
	}
	rx_buf->page = NULL;
}

int efx_probe_rx_queue(struct efx_rx_queue *rx_queue)
{
	struct efx_nic *efx = rx_queue->efx;
	unsigned int entries;
	int rc;

	/* Create the smallest power-of-two aligned ring */
	entries = max(roundup_pow_of_two(efx->rxq_entries), EFX_MIN_DMAQ_SIZE);
	EFX_WARN_ON_PARANOID(entries > EFX_MAX_DMAQ_SIZE);
	rx_queue->ptr_mask = entries - 1;

	netif_dbg(efx, probe, efx->net_dev,
		  "creating RX queue %d size %#x mask %#x\n",
		  efx_rx_queue_index(rx_queue), efx->rxq_entries,
		  rx_queue->ptr_mask);

	/* Allocate RX buffers */
	rx_queue->buffer = kcalloc(entries, sizeof(*rx_queue->buffer),
				   GFP_KERNEL);
	if (!rx_queue->buffer)
		return -ENOMEM;

	rc = efx_nic_probe_rx(rx_queue);
	if (rc) {
		kfree(rx_queue->buffer);
		rx_queue->buffer = NULL;
	}

	return rc;
}

void efx_init_rx_queue(struct efx_rx_queue *rx_queue)
{
	unsigned int max_fill, trigger, max_trigger;
	struct efx_nic *efx = rx_queue->efx;
	int rc = 0;

	netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
		  "initialising RX queue %d\n", efx_rx_queue_index(rx_queue));

	/* Initialise ptr fields */
	rx_queue->added_count = 0;
	rx_queue->notified_count = 0;
	rx_queue->removed_count = 0;
	rx_queue->min_fill = -1U;
	efx_init_rx_recycle_ring(rx_queue);

	rx_queue->page_remove = 0;
	rx_queue->page_add = rx_queue->page_ptr_mask + 1;
	rx_queue->page_recycle_count = 0;
	rx_queue->page_recycle_failed = 0;
	rx_queue->page_recycle_full = 0;

	/* Initialise limit fields */
	max_fill = efx->rxq_entries - EFX_RXD_HEAD_ROOM;
	max_trigger =
		max_fill - efx->rx_pages_per_batch * efx->rx_bufs_per_page;
	if (rx_refill_threshold != 0) {
		trigger = max_fill * min(rx_refill_threshold, 100U) / 100U;
		if (trigger > max_trigger)
			trigger = max_trigger;
	} else {
		trigger = max_trigger;
	}

	rx_queue->max_fill = max_fill;
	rx_queue->fast_fill_trigger = trigger;
	rx_queue->refill_enabled = true;

	/* Initialise XDP queue information */
	rc = xdp_rxq_info_reg(&rx_queue->xdp_rxq_info, efx->net_dev,
			      rx_queue->core_index);

	if (rc) {
		netif_err(efx, rx_err, efx->net_dev,
			  "Failure to initialise XDP queue information rc=%d\n",
			  rc);
		efx->xdp_rxq_info_failed = true;
	} else {
		rx_queue->xdp_rxq_info_valid = true;
	}

	/* Set up RX descriptor ring */
	efx_nic_init_rx(rx_queue);
}

void efx_fini_rx_queue(struct efx_rx_queue *rx_queue)
{
	struct efx_rx_buffer *rx_buf;
	int i;

	netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
		  "shutting down RX queue %d\n", efx_rx_queue_index(rx_queue));

	del_timer_sync(&rx_queue->slow_fill);

	/* Release RX buffers from the current read ptr to the write ptr */
	if (rx_queue->buffer) {
		for (i = rx_queue->removed_count; i < rx_queue->added_count;
		     i++) {
			unsigned int index = i & rx_queue->ptr_mask;

			rx_buf = efx_rx_buffer(rx_queue, index);
			efx_fini_rx_buffer(rx_queue, rx_buf);
		}
	}

	efx_fini_rx_recycle_ring(rx_queue);

	if (rx_queue->xdp_rxq_info_valid)
		xdp_rxq_info_unreg(&rx_queue->xdp_rxq_info);

	rx_queue->xdp_rxq_info_valid = false;
}

void efx_remove_rx_queue(struct efx_rx_queue *rx_queue)
{
	netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
		  "destroying RX queue %d\n", efx_rx_queue_index(rx_queue));

	efx_nic_remove_rx(rx_queue);

	kfree(rx_queue->buffer);
	rx_queue->buffer = NULL;
}

/* Unmap a DMA-mapped page.  This function is only called for the final RX
 * buffer in a page.
 */
void efx_unmap_rx_buffer(struct efx_nic *efx,
			 struct efx_rx_buffer *rx_buf)
{
	struct page *page = rx_buf->page;

	if (page) {
		struct efx_rx_page_state *state = page_address(page);

		dma_unmap_page(&efx->pci_dev->dev,
			       state->dma_addr,
			       PAGE_SIZE << efx->rx_buffer_order,
			       DMA_FROM_DEVICE);
	}
}

void efx_free_rx_buffers(struct efx_rx_queue *rx_queue,
			 struct efx_rx_buffer *rx_buf,
			 unsigned int num_bufs)
{
	do {
		if (rx_buf->page) {
			put_page(rx_buf->page);
			rx_buf->page = NULL;
		}
		rx_buf = efx_rx_buf_next(rx_queue, rx_buf);
	} while (--num_bufs);
}

void efx_rx_slow_fill(struct timer_list *t)
{
	struct efx_rx_queue *rx_queue = from_timer(rx_queue, t, slow_fill);

	/* Post an event to cause NAPI to run and refill the queue */
	efx_nic_generate_fill_event(rx_queue);
	++rx_queue->slow_fill_count;
}

void efx_schedule_slow_fill(struct efx_rx_queue *rx_queue)
{
	mod_timer(&rx_queue->slow_fill, jiffies + msecs_to_jiffies(10));
}

/* efx_init_rx_buffers - create EFX_RX_BATCH page-based RX buffers
 *
 * @rx_queue:		Efx RX queue
 *
 * This allocates a batch of pages, maps them for DMA, and populates
 * struct efx_rx_buffers for each one. Return a negative error code or
 * 0 on success. If a single page can be used for multiple buffers,
 * then the page will either be inserted fully, or not at all.
 */
static int efx_init_rx_buffers(struct efx_rx_queue *rx_queue, bool atomic)
{
	unsigned int page_offset, index, count;
	struct efx_nic *efx = rx_queue->efx;
	struct efx_rx_page_state *state;
	struct efx_rx_buffer *rx_buf;
	dma_addr_t dma_addr;
	struct page *page;

	count = 0;
	do {
		page = efx_reuse_page(rx_queue);
		if (page == NULL) {
			page = alloc_pages(__GFP_COMP |
					   (atomic ? GFP_ATOMIC : GFP_KERNEL),
					   efx->rx_buffer_order);
			if (unlikely(page == NULL))
				return -ENOMEM;
			dma_addr =
				dma_map_page(&efx->pci_dev->dev, page, 0,
					     PAGE_SIZE << efx->rx_buffer_order,
					     DMA_FROM_DEVICE);
			if (unlikely(dma_mapping_error(&efx->pci_dev->dev,
						       dma_addr))) {
				__free_pages(page, efx->rx_buffer_order);
				return -EIO;
			}
			state = page_address(page);
			state->dma_addr = dma_addr;
		} else {
			state = page_address(page);
			dma_addr = state->dma_addr;
		}

		dma_addr += sizeof(struct efx_rx_page_state);
		page_offset = sizeof(struct efx_rx_page_state);

		do {
			index = rx_queue->added_count & rx_queue->ptr_mask;
			rx_buf = efx_rx_buffer(rx_queue, index);
			rx_buf->dma_addr = dma_addr + efx->rx_ip_align +
					   XDP_PACKET_HEADROOM;
			rx_buf->page = page;
			rx_buf->page_offset = page_offset + efx->rx_ip_align +
					      XDP_PACKET_HEADROOM;
			rx_buf->len = efx->rx_dma_len;
			rx_buf->flags = 0;
			++rx_queue->added_count;
			get_page(page);
			dma_addr += efx->rx_page_buf_step;
			page_offset += efx->rx_page_buf_step;
		} while (page_offset + efx->rx_page_buf_step <= PAGE_SIZE);

		rx_buf->flags = EFX_RX_BUF_LAST_IN_PAGE;
	} while (++count < efx->rx_pages_per_batch);

	return 0;
}

void efx_rx_config_page_split(struct efx_nic *efx)
{
	efx->rx_page_buf_step = ALIGN(efx->rx_dma_len + efx->rx_ip_align +
				      XDP_PACKET_HEADROOM,
				      EFX_RX_BUF_ALIGNMENT);
	efx->rx_bufs_per_page = efx->rx_buffer_order ? 1 :
		((PAGE_SIZE - sizeof(struct efx_rx_page_state)) /
		efx->rx_page_buf_step);
	efx->rx_buffer_truesize = (PAGE_SIZE << efx->rx_buffer_order) /
		efx->rx_bufs_per_page;
	efx->rx_pages_per_batch = DIV_ROUND_UP(EFX_RX_PREFERRED_BATCH,
					       efx->rx_bufs_per_page);
}

/* efx_fast_push_rx_descriptors - push new RX descriptors quickly
 * @rx_queue:		RX descriptor queue
 *
 * This will aim to fill the RX descriptor queue up to
 * @rx_queue->@max_fill. If there is insufficient atomic
 * memory to do so, a slow fill will be scheduled.
 *
 * The caller must provide serialisation (none is used here). In practise,
 * this means this function must run from the NAPI handler, or be called
 * when NAPI is disabled.
 */
void efx_fast_push_rx_descriptors(struct efx_rx_queue *rx_queue, bool atomic)
{
	struct efx_nic *efx = rx_queue->efx;
	unsigned int fill_level, batch_size;
	int space, rc = 0;

	if (!rx_queue->refill_enabled)
		return;

	/* Calculate current fill level, and exit if we don't need to fill */
	fill_level = (rx_queue->added_count - rx_queue->removed_count);
	EFX_WARN_ON_ONCE_PARANOID(fill_level > rx_queue->efx->rxq_entries);
	if (fill_level >= rx_queue->fast_fill_trigger)
		goto out;

	/* Record minimum fill level */
	if (unlikely(fill_level < rx_queue->min_fill)) {
		if (fill_level)
			rx_queue->min_fill = fill_level;
	}

	batch_size = efx->rx_pages_per_batch * efx->rx_bufs_per_page;
	space = rx_queue->max_fill - fill_level;
	EFX_WARN_ON_ONCE_PARANOID(space < batch_size);

	netif_vdbg(rx_queue->efx, rx_status, rx_queue->efx->net_dev,
		   "RX queue %d fast-filling descriptor ring from"
		   " level %d to level %d\n",
		   efx_rx_queue_index(rx_queue), fill_level,
		   rx_queue->max_fill);

	do {
		rc = efx_init_rx_buffers(rx_queue, atomic);
		if (unlikely(rc)) {
			/* Ensure that we don't leave the rx queue empty */
			efx_schedule_slow_fill(rx_queue);
			goto out;
		}
	} while ((space -= batch_size) >= batch_size);

	netif_vdbg(rx_queue->efx, rx_status, rx_queue->efx->net_dev,
		   "RX queue %d fast-filled descriptor ring "
		   "to level %d\n", efx_rx_queue_index(rx_queue),
		   rx_queue->added_count - rx_queue->removed_count);

 out:
	if (rx_queue->notified_count != rx_queue->added_count)
		efx_nic_notify_rx_desc(rx_queue);
}

/* Pass a received packet up through GRO.  GRO can handle pages
 * regardless of checksum state and skbs with a good checksum.
 */
void
efx_rx_packet_gro(struct efx_channel *channel, struct efx_rx_buffer *rx_buf,
		  unsigned int n_frags, u8 *eh)
{
	struct napi_struct *napi = &channel->napi_str;
	struct efx_nic *efx = channel->efx;
	struct sk_buff *skb;

	skb = napi_get_frags(napi);
	if (unlikely(!skb)) {
		struct efx_rx_queue *rx_queue;

		rx_queue = efx_channel_get_rx_queue(channel);
		efx_free_rx_buffers(rx_queue, rx_buf, n_frags);
		return;
	}

	if (efx->net_dev->features & NETIF_F_RXHASH)
		skb_set_hash(skb, efx_rx_buf_hash(efx, eh),
			     PKT_HASH_TYPE_L3);
	skb->ip_summed = ((rx_buf->flags & EFX_RX_PKT_CSUMMED) ?
			  CHECKSUM_UNNECESSARY : CHECKSUM_NONE);
	skb->csum_level = !!(rx_buf->flags & EFX_RX_PKT_CSUM_LEVEL);

	for (;;) {
		skb_fill_page_desc(skb, skb_shinfo(skb)->nr_frags,
				   rx_buf->page, rx_buf->page_offset,
				   rx_buf->len);
		rx_buf->page = NULL;
		skb->len += rx_buf->len;
		if (skb_shinfo(skb)->nr_frags == n_frags)
			break;

		rx_buf = efx_rx_buf_next(&channel->rx_queue, rx_buf);
	}

	skb->data_len = skb->len;
	skb->truesize += n_frags * efx->rx_buffer_truesize;

	skb_record_rx_queue(skb, channel->rx_queue.core_index);

	napi_gro_frags(napi);
}