xref: /linux/drivers/net/ethernet/intel/ice/ice_txrx.c (revision 2b245cb29421abbad508e93cdfedf81adc12edf1)

// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2018, Intel Corporation. */

/* The driver transmit and receive code */

#include <linux/prefetch.h>
#include <linux/mm.h>
#include "ice.h"

#define ICE_RX_HDR_SIZE		256

/**
 * ice_unmap_and_free_tx_buf - Release a Tx buffer
 * @ring: the ring that owns the buffer
 * @tx_buf: the buffer to free
 */
static void
ice_unmap_and_free_tx_buf(struct ice_ring *ring, struct ice_tx_buf *tx_buf)
{
	if (tx_buf->skb) {
		dev_kfree_skb_any(tx_buf->skb);
		if (dma_unmap_len(tx_buf, len))
			dma_unmap_single(ring->dev,
					 dma_unmap_addr(tx_buf, dma),
					 dma_unmap_len(tx_buf, len),
					 DMA_TO_DEVICE);
	} else if (dma_unmap_len(tx_buf, len)) {
		dma_unmap_page(ring->dev,
			       dma_unmap_addr(tx_buf, dma),
			       dma_unmap_len(tx_buf, len),
			       DMA_TO_DEVICE);
	}

	tx_buf->next_to_watch = NULL;
	tx_buf->skb = NULL;
	dma_unmap_len_set(tx_buf, len, 0);
	/* tx_buf must be completely set up in the transmit path */
}

static struct netdev_queue *txring_txq(const struct ice_ring *ring)
{
	return netdev_get_tx_queue(ring->netdev, ring->q_index);
}

/**
 * ice_clean_tx_ring - Free any empty Tx buffers
 * @tx_ring: ring to be cleaned
 */
void ice_clean_tx_ring(struct ice_ring *tx_ring)
{
	unsigned long size;
	u16 i;

	/* ring already cleared, nothing to do */
	if (!tx_ring->tx_buf)
		return;

	/* Free all the Tx ring sk_bufss */
	for (i = 0; i < tx_ring->count; i++)
		ice_unmap_and_free_tx_buf(tx_ring, &tx_ring->tx_buf[i]);

	size = sizeof(struct ice_tx_buf) * tx_ring->count;
	memset(tx_ring->tx_buf, 0, size);

	/* Zero out the descriptor ring */
	memset(tx_ring->desc, 0, tx_ring->size);

	tx_ring->next_to_use = 0;
	tx_ring->next_to_clean = 0;

	if (!tx_ring->netdev)
		return;

	/* cleanup Tx queue statistics */
	netdev_tx_reset_queue(txring_txq(tx_ring));
}

/**
 * ice_free_tx_ring - Free Tx resources per queue
 * @tx_ring: Tx descriptor ring for a specific queue
 *
 * Free all transmit software resources
 */
void ice_free_tx_ring(struct ice_ring *tx_ring)
{
	ice_clean_tx_ring(tx_ring);
	devm_kfree(tx_ring->dev, tx_ring->tx_buf);
	tx_ring->tx_buf = NULL;

	if (tx_ring->desc) {
		dmam_free_coherent(tx_ring->dev, tx_ring->size,
				   tx_ring->desc, tx_ring->dma);
		tx_ring->desc = NULL;
	}
}

/**
 * ice_clean_tx_irq - Reclaim resources after transmit completes
 * @vsi: the VSI we care about
 * @tx_ring: Tx ring to clean
 * @napi_budget: Used to determine if we are in netpoll
 *
 * Returns true if there's any budget left (e.g. the clean is finished)
 */
static bool ice_clean_tx_irq(struct ice_vsi *vsi, struct ice_ring *tx_ring,
			     int napi_budget)
{
	unsigned int total_bytes = 0, total_pkts = 0;
	unsigned int budget = vsi->work_lmt;
	s16 i = tx_ring->next_to_clean;
	struct ice_tx_desc *tx_desc;
	struct ice_tx_buf *tx_buf;

	tx_buf = &tx_ring->tx_buf[i];
	tx_desc = ICE_TX_DESC(tx_ring, i);
	i -= tx_ring->count;

	do {
		struct ice_tx_desc *eop_desc = tx_buf->next_to_watch;

		/* if next_to_watch is not set then there is no work pending */
		if (!eop_desc)
			break;

		smp_rmb();	/* prevent any other reads prior to eop_desc */

		/* if the descriptor isn't done, no work yet to do */
		if (!(eop_desc->cmd_type_offset_bsz &
		      cpu_to_le64(ICE_TX_DESC_DTYPE_DESC_DONE)))
			break;

		/* clear next_to_watch to prevent false hangs */
		tx_buf->next_to_watch = NULL;

		/* update the statistics for this packet */
		total_bytes += tx_buf->bytecount;
		total_pkts += tx_buf->gso_segs;

		/* free the skb */
		napi_consume_skb(tx_buf->skb, napi_budget);

		/* unmap skb header data */
		dma_unmap_single(tx_ring->dev,
				 dma_unmap_addr(tx_buf, dma),
				 dma_unmap_len(tx_buf, len),
				 DMA_TO_DEVICE);

		/* clear tx_buf data */
		tx_buf->skb = NULL;
		dma_unmap_len_set(tx_buf, len, 0);

		/* unmap remaining buffers */
		while (tx_desc != eop_desc) {
			tx_buf++;
			tx_desc++;
			i++;
			if (unlikely(!i)) {
				i -= tx_ring->count;
				tx_buf = tx_ring->tx_buf;
				tx_desc = ICE_TX_DESC(tx_ring, 0);
			}

			/* unmap any remaining paged data */
			if (dma_unmap_len(tx_buf, len)) {
				dma_unmap_page(tx_ring->dev,
					       dma_unmap_addr(tx_buf, dma),
					       dma_unmap_len(tx_buf, len),
					       DMA_TO_DEVICE);
				dma_unmap_len_set(tx_buf, len, 0);
			}
		}

		/* move us one more past the eop_desc for start of next pkt */
		tx_buf++;
		tx_desc++;
		i++;
		if (unlikely(!i)) {
			i -= tx_ring->count;
			tx_buf = tx_ring->tx_buf;
			tx_desc = ICE_TX_DESC(tx_ring, 0);
		}

		prefetch(tx_desc);

		/* update budget accounting */
		budget--;
	} while (likely(budget));

	i += tx_ring->count;
	tx_ring->next_to_clean = i;
	u64_stats_update_begin(&tx_ring->syncp);
	tx_ring->stats.bytes += total_bytes;
	tx_ring->stats.pkts += total_pkts;
	u64_stats_update_end(&tx_ring->syncp);
	tx_ring->q_vector->tx.total_bytes += total_bytes;
	tx_ring->q_vector->tx.total_pkts += total_pkts;

	netdev_tx_completed_queue(txring_txq(tx_ring), total_pkts,
				  total_bytes);

#define TX_WAKE_THRESHOLD ((s16)(DESC_NEEDED * 2))
	if (unlikely(total_pkts && netif_carrier_ok(tx_ring->netdev) &&
		     (ICE_DESC_UNUSED(tx_ring) >= TX_WAKE_THRESHOLD))) {
		/* Make sure that anybody stopping the queue after this
		 * sees the new next_to_clean.
		 */
		smp_mb();
		if (__netif_subqueue_stopped(tx_ring->netdev,
					     tx_ring->q_index) &&
		   !test_bit(__ICE_DOWN, vsi->state)) {
			netif_wake_subqueue(tx_ring->netdev,
					    tx_ring->q_index);
			++tx_ring->tx_stats.restart_q;
		}
	}

	return !!budget;
}

/**
 * ice_setup_tx_ring - Allocate the Tx descriptors
 * @tx_ring: the tx ring to set up
 *
 * Return 0 on success, negative on error
 */
int ice_setup_tx_ring(struct ice_ring *tx_ring)
{
	struct device *dev = tx_ring->dev;
	int bi_size;

	if (!dev)
		return -ENOMEM;

	/* warn if we are about to overwrite the pointer */
	WARN_ON(tx_ring->tx_buf);
	bi_size = sizeof(struct ice_tx_buf) * tx_ring->count;
	tx_ring->tx_buf = devm_kzalloc(dev, bi_size, GFP_KERNEL);
	if (!tx_ring->tx_buf)
		return -ENOMEM;

	/* round up to nearest 4K */
	tx_ring->size = tx_ring->count * sizeof(struct ice_tx_desc);
	tx_ring->size = ALIGN(tx_ring->size, 4096);
	tx_ring->desc = dmam_alloc_coherent(dev, tx_ring->size, &tx_ring->dma,
					    GFP_KERNEL);
	if (!tx_ring->desc) {
		dev_err(dev, "Unable to allocate memory for the Tx descriptor ring, size=%d\n",
			tx_ring->size);
		goto err;
	}

	tx_ring->next_to_use = 0;
	tx_ring->next_to_clean = 0;
	return 0;

err:
	devm_kfree(dev, tx_ring->tx_buf);
	tx_ring->tx_buf = NULL;
	return -ENOMEM;
}

/**
 * ice_clean_rx_ring - Free Rx buffers
 * @rx_ring: ring to be cleaned
 */
void ice_clean_rx_ring(struct ice_ring *rx_ring)
{
	struct device *dev = rx_ring->dev;
	unsigned long size;
	u16 i;

	/* ring already cleared, nothing to do */
	if (!rx_ring->rx_buf)
		return;

	/* Free all the Rx ring sk_buffs */
	for (i = 0; i < rx_ring->count; i++) {
		struct ice_rx_buf *rx_buf = &rx_ring->rx_buf[i];

		if (rx_buf->skb) {
			dev_kfree_skb(rx_buf->skb);
			rx_buf->skb = NULL;
		}
		if (!rx_buf->page)
			continue;

		dma_unmap_page(dev, rx_buf->dma, PAGE_SIZE, DMA_FROM_DEVICE);
		__free_pages(rx_buf->page, 0);

		rx_buf->page = NULL;
		rx_buf->page_offset = 0;
	}

	size = sizeof(struct ice_rx_buf) * rx_ring->count;
	memset(rx_ring->rx_buf, 0, size);

	/* Zero out the descriptor ring */
	memset(rx_ring->desc, 0, rx_ring->size);

	rx_ring->next_to_alloc = 0;
	rx_ring->next_to_clean = 0;
	rx_ring->next_to_use = 0;
}

/**
 * ice_free_rx_ring - Free Rx resources
 * @rx_ring: ring to clean the resources from
 *
 * Free all receive software resources
 */
void ice_free_rx_ring(struct ice_ring *rx_ring)
{
	ice_clean_rx_ring(rx_ring);
	devm_kfree(rx_ring->dev, rx_ring->rx_buf);
	rx_ring->rx_buf = NULL;

	if (rx_ring->desc) {
		dmam_free_coherent(rx_ring->dev, rx_ring->size,
				   rx_ring->desc, rx_ring->dma);
		rx_ring->desc = NULL;
	}
}

/**
 * ice_setup_rx_ring - Allocate the Rx descriptors
 * @rx_ring: the rx ring to set up
 *
 * Return 0 on success, negative on error
 */
int ice_setup_rx_ring(struct ice_ring *rx_ring)
{
	struct device *dev = rx_ring->dev;
	int bi_size;

	if (!dev)
		return -ENOMEM;

	/* warn if we are about to overwrite the pointer */
	WARN_ON(rx_ring->rx_buf);
	bi_size = sizeof(struct ice_rx_buf) * rx_ring->count;
	rx_ring->rx_buf = devm_kzalloc(dev, bi_size, GFP_KERNEL);
	if (!rx_ring->rx_buf)
		return -ENOMEM;

	/* round up to nearest 4K */
	rx_ring->size = rx_ring->count * sizeof(union ice_32byte_rx_desc);
	rx_ring->size = ALIGN(rx_ring->size, 4096);
	rx_ring->desc = dmam_alloc_coherent(dev, rx_ring->size, &rx_ring->dma,
					    GFP_KERNEL);
	if (!rx_ring->desc) {
		dev_err(dev, "Unable to allocate memory for the Rx descriptor ring, size=%d\n",
			rx_ring->size);
		goto err;
	}

	rx_ring->next_to_use = 0;
	rx_ring->next_to_clean = 0;
	return 0;

err:
	devm_kfree(dev, rx_ring->rx_buf);
	rx_ring->rx_buf = NULL;
	return -ENOMEM;
}

/**
 * ice_release_rx_desc - Store the new tail and head values
 * @rx_ring: ring to bump
 * @val: new head index
 */
static void ice_release_rx_desc(struct ice_ring *rx_ring, u32 val)
{
	rx_ring->next_to_use = val;

	/* update next to alloc since we have filled the ring */
	rx_ring->next_to_alloc = val;

	/* Force memory writes to complete before letting h/w
	 * know there are new descriptors to fetch.  (Only
	 * applicable for weak-ordered memory model archs,
	 * such as IA-64).
	 */
	wmb();
	writel(val, rx_ring->tail);
}

/**
 * ice_alloc_mapped_page - recycle or make a new page
 * @rx_ring: ring to use
 * @bi: rx_buf struct to modify
 *
 * Returns true if the page was successfully allocated or
 * reused.
 */
static bool ice_alloc_mapped_page(struct ice_ring *rx_ring,
				  struct ice_rx_buf *bi)
{
	struct page *page = bi->page;
	dma_addr_t dma;

	/* since we are recycling buffers we should seldom need to alloc */
	if (likely(page)) {
		rx_ring->rx_stats.page_reuse_count++;
		return true;
	}

	/* alloc new page for storage */
	page = alloc_page(GFP_ATOMIC | __GFP_NOWARN);
	if (unlikely(!page)) {
		rx_ring->rx_stats.alloc_page_failed++;
		return false;
	}

	/* map page for use */
	dma = dma_map_page(rx_ring->dev, page, 0, PAGE_SIZE, DMA_FROM_DEVICE);

	/* if mapping failed free memory back to system since
	 * there isn't much point in holding memory we can't use
	 */
	if (dma_mapping_error(rx_ring->dev, dma)) {
		__free_pages(page, 0);
		rx_ring->rx_stats.alloc_page_failed++;
		return false;
	}

	bi->dma = dma;
	bi->page = page;
	bi->page_offset = 0;

	return true;
}

/**
 * ice_alloc_rx_bufs - Replace used receive buffers
 * @rx_ring: ring to place buffers on
 * @cleaned_count: number of buffers to replace
 *
 * Returns false if all allocations were successful, true if any fail
 */
bool ice_alloc_rx_bufs(struct ice_ring *rx_ring, u16 cleaned_count)
{
	union ice_32b_rx_flex_desc *rx_desc;
	u16 ntu = rx_ring->next_to_use;
	struct ice_rx_buf *bi;

	/* do nothing if no valid netdev defined */
	if (!rx_ring->netdev || !cleaned_count)
		return false;

	/* get the RX descriptor and buffer based on next_to_use */
	rx_desc = ICE_RX_DESC(rx_ring, ntu);
	bi = &rx_ring->rx_buf[ntu];

	do {
		if (!ice_alloc_mapped_page(rx_ring, bi))
			goto no_bufs;

		/* Refresh the desc even if buffer_addrs didn't change
		 * because each write-back erases this info.
		 */
		rx_desc->read.pkt_addr = cpu_to_le64(bi->dma + bi->page_offset);

		rx_desc++;
		bi++;
		ntu++;
		if (unlikely(ntu == rx_ring->count)) {
			rx_desc = ICE_RX_DESC(rx_ring, 0);
			bi = rx_ring->rx_buf;
			ntu = 0;
		}

		/* clear the status bits for the next_to_use descriptor */
		rx_desc->wb.status_error0 = 0;

		cleaned_count--;
	} while (cleaned_count);

	if (rx_ring->next_to_use != ntu)
		ice_release_rx_desc(rx_ring, ntu);

	return false;

no_bufs:
	if (rx_ring->next_to_use != ntu)
		ice_release_rx_desc(rx_ring, ntu);

	/* make sure to come back via polling to try again after
	 * allocation failure
	 */
	return true;
}

/**
 * ice_page_is_reserved - check if reuse is possible
 * @page: page struct to check
 */
static bool ice_page_is_reserved(struct page *page)
{
	return (page_to_nid(page) != numa_mem_id()) || page_is_pfmemalloc(page);
}

/**
 * ice_add_rx_frag - Add contents of Rx buffer to sk_buff
 * @rx_buf: buffer containing page to add
 * @rx_desc: descriptor containing length of buffer written by hardware
 * @skb: sk_buf to place the data into
 *
 * This function will add the data contained in rx_buf->page to the skb.
 * This is done either through a direct copy if the data in the buffer is
 * less than the skb header size, otherwise it will just attach the page as
 * a frag to the skb.
 *
 * The function will then update the page offset if necessary and return
 * true if the buffer can be reused by the adapter.
 */
static bool ice_add_rx_frag(struct ice_rx_buf *rx_buf,
			    union ice_32b_rx_flex_desc *rx_desc,
			    struct sk_buff *skb)
{
#if (PAGE_SIZE < 8192)
	unsigned int truesize = ICE_RXBUF_2048;
#else
	unsigned int last_offset = PAGE_SIZE - ICE_RXBUF_2048;
	unsigned int truesize;
#endif /* PAGE_SIZE < 8192) */

	struct page *page;
	unsigned int size;

	size = le16_to_cpu(rx_desc->wb.pkt_len) &
		ICE_RX_FLX_DESC_PKT_LEN_M;

	page = rx_buf->page;

#if (PAGE_SIZE >= 8192)
	truesize = ALIGN(size, L1_CACHE_BYTES);
#endif /* PAGE_SIZE >= 8192) */

	/* will the data fit in the skb we allocated? if so, just
	 * copy it as it is pretty small anyway
	 */
	if (size <= ICE_RX_HDR_SIZE && !skb_is_nonlinear(skb)) {
		unsigned char *va = page_address(page) + rx_buf->page_offset;

		memcpy(__skb_put(skb, size), va, ALIGN(size, sizeof(long)));

		/* page is not reserved, we can reuse buffer as-is */
		if (likely(!ice_page_is_reserved(page)))
			return true;

		/* this page cannot be reused so discard it */
		__free_pages(page, 0);
		return false;
	}

	skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page,
			rx_buf->page_offset, size, truesize);

	/* avoid re-using remote pages */
	if (unlikely(ice_page_is_reserved(page)))
		return false;

#if (PAGE_SIZE < 8192)
	/* if we are only owner of page we can reuse it */
	if (unlikely(page_count(page) != 1))
		return false;

	/* flip page offset to other buffer */
	rx_buf->page_offset ^= truesize;
#else
	/* move offset up to the next cache line */
	rx_buf->page_offset += truesize;

	if (rx_buf->page_offset > last_offset)
		return false;
#endif /* PAGE_SIZE < 8192) */

	/* Even if we own the page, we are not allowed to use atomic_set()
	 * This would break get_page_unless_zero() users.
	 */
	get_page(rx_buf->page);

	return true;
}

/**
 * ice_reuse_rx_page - page flip buffer and store it back on the ring
 * @rx_ring: rx descriptor ring to store buffers on
 * @old_buf: donor buffer to have page reused
 *
 * Synchronizes page for reuse by the adapter
 */
static void ice_reuse_rx_page(struct ice_ring *rx_ring,
			      struct ice_rx_buf *old_buf)
{
	u16 nta = rx_ring->next_to_alloc;
	struct ice_rx_buf *new_buf;

	new_buf = &rx_ring->rx_buf[nta];

	/* update, and store next to alloc */
	nta++;
	rx_ring->next_to_alloc = (nta < rx_ring->count) ? nta : 0;

	/* transfer page from old buffer to new buffer */
	*new_buf = *old_buf;
}

/**
 * ice_fetch_rx_buf - Allocate skb and populate it
 * @rx_ring: rx descriptor ring to transact packets on
 * @rx_desc: descriptor containing info written by hardware
 *
 * This function allocates an skb on the fly, and populates it with the page
 * data from the current receive descriptor, taking care to set up the skb
 * correctly, as well as handling calling the page recycle function if
 * necessary.
 */
static struct sk_buff *ice_fetch_rx_buf(struct ice_ring *rx_ring,
					union ice_32b_rx_flex_desc *rx_desc)
{
	struct ice_rx_buf *rx_buf;
	struct sk_buff *skb;
	struct page *page;

	rx_buf = &rx_ring->rx_buf[rx_ring->next_to_clean];
	page = rx_buf->page;
	prefetchw(page);

	skb = rx_buf->skb;

	if (likely(!skb)) {
		u8 *page_addr = page_address(page) + rx_buf->page_offset;

		/* prefetch first cache line of first page */
		prefetch(page_addr);
#if L1_CACHE_BYTES < 128
		prefetch((void *)(page_addr + L1_CACHE_BYTES));
#endif /* L1_CACHE_BYTES */

		/* allocate a skb to store the frags */
		skb = __napi_alloc_skb(&rx_ring->q_vector->napi,
				       ICE_RX_HDR_SIZE,
				       GFP_ATOMIC | __GFP_NOWARN);
		if (unlikely(!skb)) {
			rx_ring->rx_stats.alloc_buf_failed++;
			return NULL;
		}

		/* we will be copying header into skb->data in
		 * pskb_may_pull so it is in our interest to prefetch
		 * it now to avoid a possible cache miss
		 */
		prefetchw(skb->data);

		skb_record_rx_queue(skb, rx_ring->q_index);
	} else {
		/* we are reusing so sync this buffer for CPU use */
		dma_sync_single_range_for_cpu(rx_ring->dev, rx_buf->dma,
					      rx_buf->page_offset,
					      ICE_RXBUF_2048,
					      DMA_FROM_DEVICE);

		rx_buf->skb = NULL;
	}

	/* pull page into skb */
	if (ice_add_rx_frag(rx_buf, rx_desc, skb)) {
		/* hand second half of page back to the ring */
		ice_reuse_rx_page(rx_ring, rx_buf);
		rx_ring->rx_stats.page_reuse_count++;
	} else {
		/* we are not reusing the buffer so unmap it */
		dma_unmap_page(rx_ring->dev, rx_buf->dma, PAGE_SIZE,
			       DMA_FROM_DEVICE);
	}

	/* clear contents of buffer_info */
	rx_buf->page = NULL;

	return skb;
}

/**
 * ice_pull_tail - ice specific version of skb_pull_tail
 * @skb: pointer to current skb being adjusted
 *
 * This function is an ice specific version of __pskb_pull_tail.  The
 * main difference between this version and the original function is that
 * this function can make several assumptions about the state of things
 * that allow for significant optimizations versus the standard function.
 * As a result we can do things like drop a frag and maintain an accurate
 * truesize for the skb.
 */
static void ice_pull_tail(struct sk_buff *skb)
{
	struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[0];
	unsigned int pull_len;
	unsigned char *va;

	/* it is valid to use page_address instead of kmap since we are
	 * working with pages allocated out of the lomem pool per
	 * alloc_page(GFP_ATOMIC)
	 */
	va = skb_frag_address(frag);

	/* we need the header to contain the greater of either ETH_HLEN or
	 * 60 bytes if the skb->len is less than 60 for skb_pad.
	 */
	pull_len = eth_get_headlen(va, ICE_RX_HDR_SIZE);

	/* align pull length to size of long to optimize memcpy performance */
	skb_copy_to_linear_data(skb, va, ALIGN(pull_len, sizeof(long)));

	/* update all of the pointers */
	skb_frag_size_sub(frag, pull_len);
	frag->page_offset += pull_len;
	skb->data_len -= pull_len;
	skb->tail += pull_len;
}

/**
 * ice_cleanup_headers - Correct empty headers
 * @skb: pointer to current skb being fixed
 *
 * Also address the case where we are pulling data in on pages only
 * and as such no data is present in the skb header.
 *
 * In addition if skb is not at least 60 bytes we need to pad it so that
 * it is large enough to qualify as a valid Ethernet frame.
 *
 * Returns true if an error was encountered and skb was freed.
 */
static bool ice_cleanup_headers(struct sk_buff *skb)
{
	/* place header in linear portion of buffer */
	if (skb_is_nonlinear(skb))
		ice_pull_tail(skb);

	/* if eth_skb_pad returns an error the skb was freed */
	if (eth_skb_pad(skb))
		return true;

	return false;
}

/**
 * ice_test_staterr - tests bits in Rx descriptor status and error fields
 * @rx_desc: pointer to receive descriptor (in le64 format)
 * @stat_err_bits: value to mask
 *
 * This function does some fast chicanery in order to return the
 * value of the mask which is really only used for boolean tests.
 * The status_error_len doesn't need to be shifted because it begins
 * at offset zero.
 */
static bool ice_test_staterr(union ice_32b_rx_flex_desc *rx_desc,
			     const u16 stat_err_bits)
{
	return !!(rx_desc->wb.status_error0 &
		  cpu_to_le16(stat_err_bits));
}

/**
 * ice_is_non_eop - process handling of non-EOP buffers
 * @rx_ring: Rx ring being processed
 * @rx_desc: Rx descriptor for current buffer
 * @skb: Current socket buffer containing buffer in progress
 *
 * This function updates next to clean.  If the buffer is an EOP buffer
 * this function exits returning false, otherwise it will place the
 * sk_buff in the next buffer to be chained and return true indicating
 * that this is in fact a non-EOP buffer.
 */
static bool ice_is_non_eop(struct ice_ring *rx_ring,
			   union ice_32b_rx_flex_desc *rx_desc,
			   struct sk_buff *skb)
{
	u32 ntc = rx_ring->next_to_clean + 1;

	/* fetch, update, and store next to clean */
	ntc = (ntc < rx_ring->count) ? ntc : 0;
	rx_ring->next_to_clean = ntc;

	prefetch(ICE_RX_DESC(rx_ring, ntc));

	/* if we are the last buffer then there is nothing else to do */
#define ICE_RXD_EOF BIT(ICE_RX_FLEX_DESC_STATUS0_EOF_S)
	if (likely(ice_test_staterr(rx_desc, ICE_RXD_EOF)))
		return false;

	/* place skb in next buffer to be received */
	rx_ring->rx_buf[ntc].skb = skb;
	rx_ring->rx_stats.non_eop_descs++;

	return true;
}

/**
 * ice_receive_skb - Send a completed packet up the stack
 * @rx_ring: rx ring in play
 * @skb: packet to send up
 * @vlan_tag: vlan tag for packet
 *
 * This function sends the completed packet (via. skb) up the stack using
 * gro receive functions (with/without vlan tag)
 */
static void ice_receive_skb(struct ice_ring *rx_ring, struct sk_buff *skb,
			    u16 vlan_tag)
{
	if ((rx_ring->netdev->features & NETIF_F_HW_VLAN_CTAG_RX) &&
	    (vlan_tag & VLAN_VID_MASK)) {
		__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), vlan_tag);
	}
	napi_gro_receive(&rx_ring->q_vector->napi, skb);
}

/**
 * ice_clean_rx_irq - Clean completed descriptors from Rx ring - bounce buf
 * @rx_ring: rx descriptor ring to transact packets on
 * @budget: Total limit on number of packets to process
 *
 * This function provides a "bounce buffer" approach to Rx interrupt
 * processing.  The advantage to this is that on systems that have
 * expensive overhead for IOMMU access this provides a means of avoiding
 * it by maintaining the mapping of the page to the system.
 *
 * Returns amount of work completed
 */
static int ice_clean_rx_irq(struct ice_ring *rx_ring, int budget)
{
	unsigned int total_rx_bytes = 0, total_rx_pkts = 0;
	u16 cleaned_count = ICE_DESC_UNUSED(rx_ring);
	bool failure = false;

	/* start the loop to process RX packets bounded by 'budget' */
	while (likely(total_rx_pkts < (unsigned int)budget)) {
		union ice_32b_rx_flex_desc *rx_desc;
		struct sk_buff *skb;
		u16 stat_err_bits;
		u16 vlan_tag = 0;

		/* return some buffers to hardware, one at a time is too slow */
		if (cleaned_count >= ICE_RX_BUF_WRITE) {
			failure = failure ||
				  ice_alloc_rx_bufs(rx_ring, cleaned_count);
			cleaned_count = 0;
		}

		/* get the RX desc from RX ring based on 'next_to_clean' */
		rx_desc = ICE_RX_DESC(rx_ring, rx_ring->next_to_clean);

		/* status_error_len will always be zero for unused descriptors
		 * because it's cleared in cleanup, and overlaps with hdr_addr
		 * which is always zero because packet split isn't used, if the
		 * hardware wrote DD then it will be non-zero
		 */
		stat_err_bits = BIT(ICE_RX_FLEX_DESC_STATUS0_DD_S);
		if (!ice_test_staterr(rx_desc, stat_err_bits))
			break;

		/* This memory barrier is needed to keep us from reading
		 * any other fields out of the rx_desc until we know the
		 * DD bit is set.
		 */
		dma_rmb();

		/* allocate (if needed) and populate skb */
		skb = ice_fetch_rx_buf(rx_ring, rx_desc);
		if (!skb)
			break;

		cleaned_count++;

		/* skip if it is NOP desc */
		if (ice_is_non_eop(rx_ring, rx_desc, skb))
			continue;

		stat_err_bits = BIT(ICE_RX_FLEX_DESC_STATUS0_RXE_S);
		if (unlikely(ice_test_staterr(rx_desc, stat_err_bits))) {
			dev_kfree_skb_any(skb);
			continue;
		}

		stat_err_bits = BIT(ICE_RX_FLEX_DESC_STATUS0_L2TAG1P_S);
		if (ice_test_staterr(rx_desc, stat_err_bits))
			vlan_tag = le16_to_cpu(rx_desc->wb.l2tag1);

		/* correct empty headers and pad skb if needed (to make valid
		 * ethernet frame
		 */
		if (ice_cleanup_headers(skb)) {
			skb = NULL;
			continue;
		}

		/* probably a little skewed due to removing CRC */
		total_rx_bytes += skb->len;

		/* send completed skb up the stack */
		ice_receive_skb(rx_ring, skb, vlan_tag);

		/* update budget accounting */
		total_rx_pkts++;
	}

	/* update queue and vector specific stats */
	u64_stats_update_begin(&rx_ring->syncp);
	rx_ring->stats.pkts += total_rx_pkts;
	rx_ring->stats.bytes += total_rx_bytes;
	u64_stats_update_end(&rx_ring->syncp);
	rx_ring->q_vector->rx.total_pkts += total_rx_pkts;
	rx_ring->q_vector->rx.total_bytes += total_rx_bytes;

	/* guarantee a trip back through this routine if there was a failure */
	return failure ? budget : (int)total_rx_pkts;
}

/**
 * ice_napi_poll - NAPI polling Rx/Tx cleanup routine
 * @napi: napi struct with our devices info in it
 * @budget: amount of work driver is allowed to do this pass, in packets
 *
 * This function will clean all queues associated with a q_vector.
 *
 * Returns the amount of work done
 */
int ice_napi_poll(struct napi_struct *napi, int budget)
{
	struct ice_q_vector *q_vector =
				container_of(napi, struct ice_q_vector, napi);
	struct ice_vsi *vsi = q_vector->vsi;
	struct ice_pf *pf = vsi->back;
	bool clean_complete = true;
	int budget_per_ring = 0;
	struct ice_ring *ring;
	int work_done = 0;

	/* Since the actual Tx work is minimal, we can give the Tx a larger
	 * budget and be more aggressive about cleaning up the Tx descriptors.
	 */
	ice_for_each_ring(ring, q_vector->tx)
		if (!ice_clean_tx_irq(vsi, ring, budget))
			clean_complete = false;

	/* Handle case where we are called by netpoll with a budget of 0 */
	if (budget <= 0)
		return budget;

	/* We attempt to distribute budget to each Rx queue fairly, but don't
	 * allow the budget to go below 1 because that would exit polling early.
	 */
	if (q_vector->num_ring_rx)
		budget_per_ring = max(budget / q_vector->num_ring_rx, 1);

	ice_for_each_ring(ring, q_vector->rx) {
		int cleaned;

		cleaned = ice_clean_rx_irq(ring, budget_per_ring);
		work_done += cleaned;
		/* if we clean as many as budgeted, we must not be done */
		if (cleaned >= budget_per_ring)
			clean_complete = false;
	}

	/* If work not completed, return budget and polling will return */
	if (!clean_complete)
		return budget;

	/* Work is done so exit the polling mode and re-enable the interrupt */
	napi_complete_done(napi, work_done);
	if (test_bit(ICE_FLAG_MSIX_ENA, pf->flags))
		ice_irq_dynamic_ena(&vsi->back->hw, vsi, q_vector);
	return 0;
}

/* helper function for building cmd/type/offset */
static __le64
build_ctob(u64 td_cmd, u64 td_offset, unsigned int size, u64 td_tag)
{
	return cpu_to_le64(ICE_TX_DESC_DTYPE_DATA |
			   (td_cmd    << ICE_TXD_QW1_CMD_S) |
			   (td_offset << ICE_TXD_QW1_OFFSET_S) |
			   ((u64)size << ICE_TXD_QW1_TX_BUF_SZ_S) |
			   (td_tag    << ICE_TXD_QW1_L2TAG1_S));
}

/**
 * __ice_maybe_stop_tx - 2nd level check for tx stop conditions
 * @tx_ring: the ring to be checked
 * @size: the size buffer we want to assure is available
 *
 * Returns -EBUSY if a stop is needed, else 0
 */
static int __ice_maybe_stop_tx(struct ice_ring *tx_ring, unsigned int size)
{
	netif_stop_subqueue(tx_ring->netdev, tx_ring->q_index);
	/* Memory barrier before checking head and tail */
	smp_mb();

	/* Check again in a case another CPU has just made room available. */
	if (likely(ICE_DESC_UNUSED(tx_ring) < size))
		return -EBUSY;

	/* A reprieve! - use start_subqueue because it doesn't call schedule */
	netif_start_subqueue(tx_ring->netdev, tx_ring->q_index);
	++tx_ring->tx_stats.restart_q;
	return 0;
}

/**
 * ice_maybe_stop_tx - 1st level check for tx stop conditions
 * @tx_ring: the ring to be checked
 * @size:    the size buffer we want to assure is available
 *
 * Returns 0 if stop is not needed
 */
static int ice_maybe_stop_tx(struct ice_ring *tx_ring, unsigned int size)
{
	if (likely(ICE_DESC_UNUSED(tx_ring) >= size))
		return 0;
	return __ice_maybe_stop_tx(tx_ring, size);
}

/**
 * ice_tx_map - Build the Tx descriptor
 * @tx_ring: ring to send buffer on
 * @first: first buffer info buffer to use
 *
 * This function loops over the skb data pointed to by *first
 * and gets a physical address for each memory location and programs
 * it and the length into the transmit descriptor.
 */
static void ice_tx_map(struct ice_ring *tx_ring, struct ice_tx_buf *first)
{
	u64 td_offset = 0, td_tag = 0, td_cmd = 0;
	u16 i = tx_ring->next_to_use;
	struct skb_frag_struct *frag;
	unsigned int data_len, size;
	struct ice_tx_desc *tx_desc;
	struct ice_tx_buf *tx_buf;
	struct sk_buff *skb;
	dma_addr_t dma;

	skb = first->skb;

	data_len = skb->data_len;
	size = skb_headlen(skb);

	tx_desc = ICE_TX_DESC(tx_ring, i);

	dma = dma_map_single(tx_ring->dev, skb->data, size, DMA_TO_DEVICE);

	tx_buf = first;

	for (frag = &skb_shinfo(skb)->frags[0];; frag++) {
		unsigned int max_data = ICE_MAX_DATA_PER_TXD_ALIGNED;

		if (dma_mapping_error(tx_ring->dev, dma))
			goto dma_error;

		/* record length, and DMA address */
		dma_unmap_len_set(tx_buf, len, size);
		dma_unmap_addr_set(tx_buf, dma, dma);

		/* align size to end of page */
		max_data += -dma & (ICE_MAX_READ_REQ_SIZE - 1);
		tx_desc->buf_addr = cpu_to_le64(dma);

		/* account for data chunks larger than the hardware
		 * can handle
		 */
		while (unlikely(size > ICE_MAX_DATA_PER_TXD)) {
			tx_desc->cmd_type_offset_bsz =
				build_ctob(td_cmd, td_offset, max_data, td_tag);

			tx_desc++;
			i++;

			if (i == tx_ring->count) {
				tx_desc = ICE_TX_DESC(tx_ring, 0);
				i = 0;
			}

			dma += max_data;
			size -= max_data;

			max_data = ICE_MAX_DATA_PER_TXD_ALIGNED;
			tx_desc->buf_addr = cpu_to_le64(dma);
		}

		if (likely(!data_len))
			break;

		tx_desc->cmd_type_offset_bsz = build_ctob(td_cmd, td_offset,
							  size, td_tag);

		tx_desc++;
		i++;

		if (i == tx_ring->count) {
			tx_desc = ICE_TX_DESC(tx_ring, 0);
			i = 0;
		}

		size = skb_frag_size(frag);
		data_len -= size;

		dma = skb_frag_dma_map(tx_ring->dev, frag, 0, size,
				       DMA_TO_DEVICE);

		tx_buf = &tx_ring->tx_buf[i];
	}

	/* record bytecount for BQL */
	netdev_tx_sent_queue(txring_txq(tx_ring), first->bytecount);

	/* record SW timestamp if HW timestamp is not available */
	skb_tx_timestamp(first->skb);

	i++;
	if (i == tx_ring->count)
		i = 0;

	/* write last descriptor with RS and EOP bits */
	td_cmd |= (u64)(ICE_TX_DESC_CMD_EOP | ICE_TX_DESC_CMD_RS);
	tx_desc->cmd_type_offset_bsz =
			build_ctob(td_cmd, td_offset, size, td_tag);

	/* Force memory writes to complete before letting h/w know there
	 * are new descriptors to fetch.
	 *
	 * We also use this memory barrier to make certain all of the
	 * status bits have been updated before next_to_watch is written.
	 */
	wmb();

	/* set next_to_watch value indicating a packet is present */
	first->next_to_watch = tx_desc;

	tx_ring->next_to_use = i;

	ice_maybe_stop_tx(tx_ring, DESC_NEEDED);

	/* notify HW of packet */
	if (netif_xmit_stopped(txring_txq(tx_ring)) || !skb->xmit_more) {
		writel(i, tx_ring->tail);

		/* we need this if more than one processor can write to our tail
		 * at a time, it synchronizes IO on IA64/Altix systems
		 */
		mmiowb();
	}

	return;

dma_error:
	/* clear dma mappings for failed tx_buf map */
	for (;;) {
		tx_buf = &tx_ring->tx_buf[i];
		ice_unmap_and_free_tx_buf(tx_ring, tx_buf);
		if (tx_buf == first)
			break;
		if (i == 0)
			i = tx_ring->count;
		i--;
	}

	tx_ring->next_to_use = i;
}

/**
 * ice_txd_use_count  - estimate the number of descriptors needed for Tx
 * @size: transmit request size in bytes
 *
 * Due to hardware alignment restrictions (4K alignment), we need to
 * assume that we can have no more than 12K of data per descriptor, even
 * though each descriptor can take up to 16K - 1 bytes of aligned memory.
 * Thus, we need to divide by 12K. But division is slow! Instead,
 * we decompose the operation into shifts and one relatively cheap
 * multiply operation.
 *
 * To divide by 12K, we first divide by 4K, then divide by 3:
 *     To divide by 4K, shift right by 12 bits
 *     To divide by 3, multiply by 85, then divide by 256
 *     (Divide by 256 is done by shifting right by 8 bits)
 * Finally, we add one to round up. Because 256 isn't an exact multiple of
 * 3, we'll underestimate near each multiple of 12K. This is actually more
 * accurate as we have 4K - 1 of wiggle room that we can fit into the last
 * segment.  For our purposes this is accurate out to 1M which is orders of
 * magnitude greater than our largest possible GSO size.
 *
 * This would then be implemented as:
 *     return (((size >> 12) * 85) >> 8) + 1;
 *
 * Since multiplication and division are commutative, we can reorder
 * operations into:
 *     return ((size * 85) >> 20) + 1;
 */
static unsigned int ice_txd_use_count(unsigned int size)
{
	return ((size * 85) >> 20) + 1;
}

/**
 * ice_xmit_desc_count - calculate number of tx descriptors needed
 * @skb: send buffer
 *
 * Returns number of data descriptors needed for this skb.
 */
static unsigned int ice_xmit_desc_count(struct sk_buff *skb)
{
	const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[0];
	unsigned int nr_frags = skb_shinfo(skb)->nr_frags;
	unsigned int count = 0, size = skb_headlen(skb);

	for (;;) {
		count += ice_txd_use_count(size);

		if (!nr_frags--)
			break;

		size = skb_frag_size(frag++);
	}

	return count;
}

/**
 * __ice_chk_linearize - Check if there are more than 8 buffers per packet
 * @skb: send buffer
 *
 * Note: This HW can't DMA more than 8 buffers to build a packet on the wire
 * and so we need to figure out the cases where we need to linearize the skb.
 *
 * For TSO we need to count the TSO header and segment payload separately.
 * As such we need to check cases where we have 7 fragments or more as we
 * can potentially require 9 DMA transactions, 1 for the TSO header, 1 for
 * the segment payload in the first descriptor, and another 7 for the
 * fragments.
 */
static bool __ice_chk_linearize(struct sk_buff *skb)
{
	const struct skb_frag_struct *frag, *stale;
	int nr_frags, sum;

	/* no need to check if number of frags is less than 7 */
	nr_frags = skb_shinfo(skb)->nr_frags;
	if (nr_frags < (ICE_MAX_BUF_TXD - 1))
		return false;

	/* We need to walk through the list and validate that each group
	 * of 6 fragments totals at least gso_size.
	 */
	nr_frags -= ICE_MAX_BUF_TXD - 2;
	frag = &skb_shinfo(skb)->frags[0];

	/* Initialize size to the negative value of gso_size minus 1.  We
	 * use this as the worst case scenerio in which the frag ahead
	 * of us only provides one byte which is why we are limited to 6
	 * descriptors for a single transmit as the header and previous
	 * fragment are already consuming 2 descriptors.
	 */
	sum = 1 - skb_shinfo(skb)->gso_size;

	/* Add size of frags 0 through 4 to create our initial sum */
	sum += skb_frag_size(frag++);
	sum += skb_frag_size(frag++);
	sum += skb_frag_size(frag++);
	sum += skb_frag_size(frag++);
	sum += skb_frag_size(frag++);

	/* Walk through fragments adding latest fragment, testing it, and
	 * then removing stale fragments from the sum.
	 */
	stale = &skb_shinfo(skb)->frags[0];
	for (;;) {
		sum += skb_frag_size(frag++);

		/* if sum is negative we failed to make sufficient progress */
		if (sum < 0)
			return true;

		if (!nr_frags--)
			break;

		sum -= skb_frag_size(stale++);
	}

	return false;
}

/**
 * ice_chk_linearize - Check if there are more than 8 fragments per packet
 * @skb:      send buffer
 * @count:    number of buffers used
 *
 * Note: Our HW can't scatter-gather more than 8 fragments to build
 * a packet on the wire and so we need to figure out the cases where we
 * need to linearize the skb.
 */
static bool ice_chk_linearize(struct sk_buff *skb, unsigned int count)
{
	/* Both TSO and single send will work if count is less than 8 */
	if (likely(count < ICE_MAX_BUF_TXD))
		return false;

	if (skb_is_gso(skb))
		return __ice_chk_linearize(skb);

	/* we can support up to 8 data buffers for a single send */
	return count != ICE_MAX_BUF_TXD;
}

/**
 * ice_xmit_frame_ring - Sends buffer on Tx ring
 * @skb: send buffer
 * @tx_ring: ring to send buffer on
 *
 * Returns NETDEV_TX_OK if sent, else an error code
 */
static netdev_tx_t
ice_xmit_frame_ring(struct sk_buff *skb, struct ice_ring *tx_ring)
{
	struct ice_tx_buf *first;
	unsigned int count;

	count = ice_xmit_desc_count(skb);
	if (ice_chk_linearize(skb, count)) {
		if (__skb_linearize(skb))
			goto out_drop;
		count = ice_txd_use_count(skb->len);
		tx_ring->tx_stats.tx_linearize++;
	}

	/* need: 1 descriptor per page * PAGE_SIZE/ICE_MAX_DATA_PER_TXD,
	 *       + 1 desc for skb_head_len/ICE_MAX_DATA_PER_TXD,
	 *       + 4 desc gap to avoid the cache line where head is,
	 *       + 1 desc for context descriptor,
	 * otherwise try next time
	 */
	if (ice_maybe_stop_tx(tx_ring, count + 4 + 1)) {
		tx_ring->tx_stats.tx_busy++;
		return NETDEV_TX_BUSY;
	}

	/* record the location of the first descriptor for this packet */
	first = &tx_ring->tx_buf[tx_ring->next_to_use];
	first->skb = skb;
	first->bytecount = max_t(unsigned int, skb->len, ETH_ZLEN);
	first->gso_segs = 1;

	ice_tx_map(tx_ring, first);
	return NETDEV_TX_OK;

out_drop:
	dev_kfree_skb_any(skb);
	return NETDEV_TX_OK;
}

/**
 * ice_start_xmit - Selects the correct VSI and Tx queue to send buffer
 * @skb: send buffer
 * @netdev: network interface device structure
 *
 * Returns NETDEV_TX_OK if sent, else an error code
 */
netdev_tx_t ice_start_xmit(struct sk_buff *skb, struct net_device *netdev)
{
	struct ice_netdev_priv *np = netdev_priv(netdev);
	struct ice_vsi *vsi = np->vsi;
	struct ice_ring *tx_ring;

	tx_ring = vsi->tx_rings[skb->queue_mapping];

	/* hardware can't handle really short frames, hardware padding works
	 * beyond this point
	 */
	if (skb_put_padto(skb, ICE_MIN_TX_LEN))
		return NETDEV_TX_OK;

	return ice_xmit_frame_ring(skb, tx_ring);
}