WIP FPC-III support

[linux/fpc-iii.git] / drivers / net / ethernet / sfc / falcon / rx.c

// SPDX-License-Identifier: GPL-2.0-only
/****************************************************************************
 * Driver for Solarflare network controllers and boards
 * Copyright 2005-2006 Fen Systems Ltd.
 * Copyright 2005-2013 Solarflare Communications Inc.
 */

#include <linux/socket.h>
#include <linux/in.h>
#include <linux/slab.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/prefetch.h>
#include <linux/moduleparam.h>
#include <linux/iommu.h>
#include <net/ip.h>
#include <net/checksum.h>
#include "net_driver.h"
#include "efx.h"
#include "filter.h"
#include "nic.h"
#include "selftest.h"
#include "workarounds.h"

/* Preferred number of descriptors to fill at once */
#define EF4_RX_PREFERRED_BATCH 8U

/* 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 EF4_RECYCLE_RING_SIZE_IOMMU 4096
#define EF4_RECYCLE_RING_SIZE_NOIOMMU (2 * EF4_RX_PREFERRED_BATCH)

/* Size of buffer allocated for skb header area. */
#define EF4_SKB_HEADERS  128u

/* 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;

/* Each packet can consume up to ceil(max_frame_len / buffer_size) buffers */
#define EF4_RX_MAX_FRAGS DIV_ROUND_UP(EF4_MAX_FRAME_LEN(EF4_MAX_MTU), \
                                      EF4_RX_USR_BUF_SIZE)

/*
 * RX maximum head room required.
 *
 * This must be at least 1 to prevent overflow, plus one packet-worth
 * to allow pipelined receives.
 */
#define EF4_RXD_HEAD_ROOM (1 + EF4_RX_MAX_FRAGS)

static inline u8 *ef4_rx_buf_va(struct ef4_rx_buffer *buf)
{
        return page_address(buf->page) + buf->page_offset;
}

static inline u32 ef4_rx_buf_hash(struct ef4_nic *efx, const u8 *eh)
{
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
        return __le32_to_cpup((const __le32 *)(eh + efx->rx_packet_hash_offset));
#else
        const u8 *data = eh + efx->rx_packet_hash_offset;
        return (u32)data[0]       |
               (u32)data[1] << 8  |
               (u32)data[2] << 16 |
               (u32)data[3] << 24;
#endif
}

static inline struct ef4_rx_buffer *
ef4_rx_buf_next(struct ef4_rx_queue *rx_queue, struct ef4_rx_buffer *rx_buf)
{
        if (unlikely(rx_buf == ef4_rx_buffer(rx_queue, rx_queue->ptr_mask)))
                return ef4_rx_buffer(rx_queue, 0);
        else
                return rx_buf + 1;
}

static inline void ef4_sync_rx_buffer(struct ef4_nic *efx,
                                      struct ef4_rx_buffer *rx_buf,
                                      unsigned int len)
{
        dma_sync_single_for_cpu(&efx->pci_dev->dev, rx_buf->dma_addr, len,
                                DMA_FROM_DEVICE);
}

void ef4_rx_config_page_split(struct ef4_nic *efx)
{
        efx->rx_page_buf_step = ALIGN(efx->rx_dma_len + efx->rx_ip_align,
                                      EF4_RX_BUF_ALIGNMENT);
        efx->rx_bufs_per_page = efx->rx_buffer_order ? 1 :
                ((PAGE_SIZE - sizeof(struct ef4_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(EF4_RX_PREFERRED_BATCH,
                                               efx->rx_bufs_per_page);
}

/* Check the RX page recycle ring for a page that can be reused. */
static struct page *ef4_reuse_page(struct ef4_rx_queue *rx_queue)
{
        struct ef4_nic *efx = rx_queue->efx;
        struct page *page;
        struct ef4_rx_page_state *state;
        unsigned index;

        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;
}

/**
 * ef4_init_rx_buffers - create EF4_RX_BATCH page-based RX buffers
 *
 * @rx_queue:           Efx RX queue
 * @atomic:             control memory allocation flags
 *
 * This allocates a batch of pages, maps them for DMA, and populates
 * struct ef4_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 ef4_init_rx_buffers(struct ef4_rx_queue *rx_queue, bool atomic)
{
        struct ef4_nic *efx = rx_queue->efx;
        struct ef4_rx_buffer *rx_buf;
        struct page *page;
        unsigned int page_offset;
        struct ef4_rx_page_state *state;
        dma_addr_t dma_addr;
        unsigned index, count;

        count = 0;
        do {
                page = ef4_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 ef4_rx_page_state);
                page_offset = sizeof(struct ef4_rx_page_state);

                do {
                        index = rx_queue->added_count & rx_queue->ptr_mask;
                        rx_buf = ef4_rx_buffer(rx_queue, index);
                        rx_buf->dma_addr = dma_addr + efx->rx_ip_align;
                        rx_buf->page = page;
                        rx_buf->page_offset = page_offset + efx->rx_ip_align;
                        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 = EF4_RX_BUF_LAST_IN_PAGE;
        } while (++count < efx->rx_pages_per_batch);

        return 0;
}

/* Unmap a DMA-mapped page.  This function is only called for the final RX
 * buffer in a page.
 */
static void ef4_unmap_rx_buffer(struct ef4_nic *efx,
                                struct ef4_rx_buffer *rx_buf)
{
        struct page *page = rx_buf->page;

        if (page) {
                struct ef4_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);
        }
}

static void ef4_free_rx_buffers(struct ef4_rx_queue *rx_queue,
                                struct ef4_rx_buffer *rx_buf,
                                unsigned int num_bufs)
{
        do {
                if (rx_buf->page) {
                        put_page(rx_buf->page);
                        rx_buf->page = NULL;
                }
                rx_buf = ef4_rx_buf_next(rx_queue, rx_buf);
        } while (--num_bufs);
}

/* 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 ef4_recycle_rx_page(struct ef4_channel *channel,
                                struct ef4_rx_buffer *rx_buf)
{
        struct page *page = rx_buf->page;
        struct ef4_rx_queue *rx_queue = ef4_channel_get_rx_queue(channel);
        struct ef4_nic *efx = rx_queue->efx;
        unsigned index;

        /* Only recycle the page after processing the final buffer. */
        if (!(rx_buf->flags & EF4_RX_BUF_LAST_IN_PAGE))
                return;

        index = rx_queue->page_add & rx_queue->page_ptr_mask;
        if (rx_queue->page_ring[index] == NULL) {
                unsigned 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;
        ef4_unmap_rx_buffer(efx, rx_buf);
        put_page(rx_buf->page);
}

static void ef4_fini_rx_buffer(struct ef4_rx_queue *rx_queue,
                               struct ef4_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 & EF4_RX_BUF_LAST_IN_PAGE) {
                ef4_unmap_rx_buffer(rx_queue->efx, rx_buf);
                ef4_free_rx_buffers(rx_queue, rx_buf, 1);
        }
        rx_buf->page = NULL;
}

/* Recycle the pages that are used by buffers that have just been received. */
static void ef4_recycle_rx_pages(struct ef4_channel *channel,
                                 struct ef4_rx_buffer *rx_buf,
                                 unsigned int n_frags)
{
        struct ef4_rx_queue *rx_queue = ef4_channel_get_rx_queue(channel);

        do {
                ef4_recycle_rx_page(channel, rx_buf);
                rx_buf = ef4_rx_buf_next(rx_queue, rx_buf);
        } while (--n_frags);
}

static void ef4_discard_rx_packet(struct ef4_channel *channel,
                                  struct ef4_rx_buffer *rx_buf,
                                  unsigned int n_frags)
{
        struct ef4_rx_queue *rx_queue = ef4_channel_get_rx_queue(channel);

        ef4_recycle_rx_pages(channel, rx_buf, n_frags);

        ef4_free_rx_buffers(rx_queue, rx_buf, n_frags);
}

/**
 * ef4_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.
 * @atomic: control memory allocation flags
 *
 * 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 ef4_fast_push_rx_descriptors(struct ef4_rx_queue *rx_queue, bool atomic)
{
        struct ef4_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);
        EF4_BUG_ON_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;
        EF4_BUG_ON_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",
                   ef4_rx_queue_index(rx_queue), fill_level,
                   rx_queue->max_fill);


        do {
                rc = ef4_init_rx_buffers(rx_queue, atomic);
                if (unlikely(rc)) {
                        /* Ensure that we don't leave the rx queue empty */
                        if (rx_queue->added_count == rx_queue->removed_count)
                                ef4_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", ef4_rx_queue_index(rx_queue),
                   rx_queue->added_count - rx_queue->removed_count);

 out:
        if (rx_queue->notified_count != rx_queue->added_count)
                ef4_nic_notify_rx_desc(rx_queue);
}

void ef4_rx_slow_fill(struct timer_list *t)
{
        struct ef4_rx_queue *rx_queue = from_timer(rx_queue, t, slow_fill);

        /* Post an event to cause NAPI to run and refill the queue */
        ef4_nic_generate_fill_event(rx_queue);
        ++rx_queue->slow_fill_count;
}

static void ef4_rx_packet__check_len(struct ef4_rx_queue *rx_queue,
                                     struct ef4_rx_buffer *rx_buf,
                                     int len)
{
        struct ef4_nic *efx = rx_queue->efx;
        unsigned max_len = rx_buf->len - efx->type->rx_buffer_padding;

        if (likely(len <= max_len))
                return;

        /* The packet must be discarded, but this is only a fatal error
         * if the caller indicated it was
         */
        rx_buf->flags |= EF4_RX_PKT_DISCARD;

        if ((len > rx_buf->len) && EF4_WORKAROUND_8071(efx)) {
                if (net_ratelimit())
                        netif_err(efx, rx_err, efx->net_dev,
                                  " RX queue %d seriously overlength "
                                  "RX event (0x%x > 0x%x+0x%x). Leaking\n",
                                  ef4_rx_queue_index(rx_queue), len, max_len,
                                  efx->type->rx_buffer_padding);
                ef4_schedule_reset(efx, RESET_TYPE_RX_RECOVERY);
        } else {
                if (net_ratelimit())
                        netif_err(efx, rx_err, efx->net_dev,
                                  " RX queue %d overlength RX event "
                                  "(0x%x > 0x%x)\n",
                                  ef4_rx_queue_index(rx_queue), len, max_len);
        }

        ef4_rx_queue_channel(rx_queue)->n_rx_overlength++;
}

/* Pass a received packet up through GRO.  GRO can handle pages
 * regardless of checksum state and skbs with a good checksum.
 */
static void
ef4_rx_packet_gro(struct ef4_channel *channel, struct ef4_rx_buffer *rx_buf,
                  unsigned int n_frags, u8 *eh)
{
        struct napi_struct *napi = &channel->napi_str;
        struct ef4_nic *efx = channel->efx;
        struct sk_buff *skb;

        skb = napi_get_frags(napi);
        if (unlikely(!skb)) {
                struct ef4_rx_queue *rx_queue;

                rx_queue = ef4_channel_get_rx_queue(channel);
                ef4_free_rx_buffers(rx_queue, rx_buf, n_frags);
                return;
        }

        if (efx->net_dev->features & NETIF_F_RXHASH)
                skb_set_hash(skb, ef4_rx_buf_hash(efx, eh),
                             PKT_HASH_TYPE_L3);
        skb->ip_summed = ((rx_buf->flags & EF4_RX_PKT_CSUMMED) ?
                          CHECKSUM_UNNECESSARY : CHECKSUM_NONE);

        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 = ef4_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);
}

/* Allocate and construct an SKB around page fragments */
static struct sk_buff *ef4_rx_mk_skb(struct ef4_channel *channel,
                                     struct ef4_rx_buffer *rx_buf,
                                     unsigned int n_frags,
                                     u8 *eh, int hdr_len)
{
        struct ef4_nic *efx = channel->efx;
        struct sk_buff *skb;

        /* Allocate an SKB to store the headers */
        skb = netdev_alloc_skb(efx->net_dev,
                               efx->rx_ip_align + efx->rx_prefix_size +
                               hdr_len);
        if (unlikely(skb == NULL)) {
                atomic_inc(&efx->n_rx_noskb_drops);
                return NULL;
        }

        EF4_BUG_ON_PARANOID(rx_buf->len < hdr_len);

        memcpy(skb->data + efx->rx_ip_align, eh - efx->rx_prefix_size,
               efx->rx_prefix_size + hdr_len);
        skb_reserve(skb, efx->rx_ip_align + efx->rx_prefix_size);
        __skb_put(skb, hdr_len);

        /* Append the remaining page(s) onto the frag list */
        if (rx_buf->len > hdr_len) {
                rx_buf->page_offset += hdr_len;
                rx_buf->len -= hdr_len;

                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;
                        skb->data_len += rx_buf->len;
                        if (skb_shinfo(skb)->nr_frags == n_frags)
                                break;

                        rx_buf = ef4_rx_buf_next(&channel->rx_queue, rx_buf);
                }
        } else {
                __free_pages(rx_buf->page, efx->rx_buffer_order);
                rx_buf->page = NULL;
                n_frags = 0;
        }

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

        /* Move past the ethernet header */
        skb->protocol = eth_type_trans(skb, efx->net_dev);

        skb_mark_napi_id(skb, &channel->napi_str);

        return skb;
}

void ef4_rx_packet(struct ef4_rx_queue *rx_queue, unsigned int index,
                   unsigned int n_frags, unsigned int len, u16 flags)
{
        struct ef4_nic *efx = rx_queue->efx;
        struct ef4_channel *channel = ef4_rx_queue_channel(rx_queue);
        struct ef4_rx_buffer *rx_buf;

        rx_queue->rx_packets++;

        rx_buf = ef4_rx_buffer(rx_queue, index);
        rx_buf->flags |= flags;

        /* Validate the number of fragments and completed length */
        if (n_frags == 1) {
                if (!(flags & EF4_RX_PKT_PREFIX_LEN))
                        ef4_rx_packet__check_len(rx_queue, rx_buf, len);
        } else if (unlikely(n_frags > EF4_RX_MAX_FRAGS) ||
                   unlikely(len <= (n_frags - 1) * efx->rx_dma_len) ||
                   unlikely(len > n_frags * efx->rx_dma_len) ||
                   unlikely(!efx->rx_scatter)) {
                /* If this isn't an explicit discard request, either
                 * the hardware or the driver is broken.
                 */
                WARN_ON(!(len == 0 && rx_buf->flags & EF4_RX_PKT_DISCARD));
                rx_buf->flags |= EF4_RX_PKT_DISCARD;
        }

        netif_vdbg(efx, rx_status, efx->net_dev,
                   "RX queue %d received ids %x-%x len %d %s%s\n",
                   ef4_rx_queue_index(rx_queue), index,
                   (index + n_frags - 1) & rx_queue->ptr_mask, len,
                   (rx_buf->flags & EF4_RX_PKT_CSUMMED) ? " [SUMMED]" : "",
                   (rx_buf->flags & EF4_RX_PKT_DISCARD) ? " [DISCARD]" : "");

        /* Discard packet, if instructed to do so.  Process the
         * previous receive first.
         */
        if (unlikely(rx_buf->flags & EF4_RX_PKT_DISCARD)) {
                ef4_rx_flush_packet(channel);
                ef4_discard_rx_packet(channel, rx_buf, n_frags);
                return;
        }

        if (n_frags == 1 && !(flags & EF4_RX_PKT_PREFIX_LEN))
                rx_buf->len = len;

        /* Release and/or sync the DMA mapping - assumes all RX buffers
         * consumed in-order per RX queue.
         */
        ef4_sync_rx_buffer(efx, rx_buf, rx_buf->len);

        /* Prefetch nice and early so data will (hopefully) be in cache by
         * the time we look at it.
         */
        prefetch(ef4_rx_buf_va(rx_buf));

        rx_buf->page_offset += efx->rx_prefix_size;
        rx_buf->len -= efx->rx_prefix_size;

        if (n_frags > 1) {
                /* Release/sync DMA mapping for additional fragments.
                 * Fix length for last fragment.
                 */
                unsigned int tail_frags = n_frags - 1;

                for (;;) {
                        rx_buf = ef4_rx_buf_next(rx_queue, rx_buf);
                        if (--tail_frags == 0)
                                break;
                        ef4_sync_rx_buffer(efx, rx_buf, efx->rx_dma_len);
                }
                rx_buf->len = len - (n_frags - 1) * efx->rx_dma_len;
                ef4_sync_rx_buffer(efx, rx_buf, rx_buf->len);
        }

        /* All fragments have been DMA-synced, so recycle pages. */
        rx_buf = ef4_rx_buffer(rx_queue, index);
        ef4_recycle_rx_pages(channel, rx_buf, n_frags);

        /* Pipeline receives so that we give time for packet headers to be
         * prefetched into cache.
         */
        ef4_rx_flush_packet(channel);
        channel->rx_pkt_n_frags = n_frags;
        channel->rx_pkt_index = index;
}

static void ef4_rx_deliver(struct ef4_channel *channel, u8 *eh,
                           struct ef4_rx_buffer *rx_buf,
                           unsigned int n_frags)
{
        struct sk_buff *skb;
        u16 hdr_len = min_t(u16, rx_buf->len, EF4_SKB_HEADERS);

        skb = ef4_rx_mk_skb(channel, rx_buf, n_frags, eh, hdr_len);
        if (unlikely(skb == NULL)) {
                struct ef4_rx_queue *rx_queue;

                rx_queue = ef4_channel_get_rx_queue(channel);
                ef4_free_rx_buffers(rx_queue, rx_buf, n_frags);
                return;
        }
        skb_record_rx_queue(skb, channel->rx_queue.core_index);

        /* Set the SKB flags */
        skb_checksum_none_assert(skb);
        if (likely(rx_buf->flags & EF4_RX_PKT_CSUMMED))
                skb->ip_summed = CHECKSUM_UNNECESSARY;

        if (channel->type->receive_skb)
                if (channel->type->receive_skb(channel, skb))
                        return;

        /* Pass the packet up */
        netif_receive_skb(skb);
}

/* Handle a received packet.  Second half: Touches packet payload. */
void __ef4_rx_packet(struct ef4_channel *channel)
{
        struct ef4_nic *efx = channel->efx;
        struct ef4_rx_buffer *rx_buf =
                ef4_rx_buffer(&channel->rx_queue, channel->rx_pkt_index);
        u8 *eh = ef4_rx_buf_va(rx_buf);

        /* Read length from the prefix if necessary.  This already
         * excludes the length of the prefix itself.
         */
        if (rx_buf->flags & EF4_RX_PKT_PREFIX_LEN)
                rx_buf->len = le16_to_cpup((__le16 *)
                                           (eh + efx->rx_packet_len_offset));

        /* If we're in loopback test, then pass the packet directly to the
         * loopback layer, and free the rx_buf here
         */
        if (unlikely(efx->loopback_selftest)) {
                struct ef4_rx_queue *rx_queue;

                ef4_loopback_rx_packet(efx, eh, rx_buf->len);
                rx_queue = ef4_channel_get_rx_queue(channel);
                ef4_free_rx_buffers(rx_queue, rx_buf,
                                    channel->rx_pkt_n_frags);
                goto out;
        }

        if (unlikely(!(efx->net_dev->features & NETIF_F_RXCSUM)))
                rx_buf->flags &= ~EF4_RX_PKT_CSUMMED;

        if ((rx_buf->flags & EF4_RX_PKT_TCP) && !channel->type->receive_skb)
                ef4_rx_packet_gro(channel, rx_buf, channel->rx_pkt_n_frags, eh);
        else
                ef4_rx_deliver(channel, eh, rx_buf, channel->rx_pkt_n_frags);
out:
        channel->rx_pkt_n_frags = 0;
}

int ef4_probe_rx_queue(struct ef4_rx_queue *rx_queue)
{
        struct ef4_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), EF4_MIN_DMAQ_SIZE);
        EF4_BUG_ON_PARANOID(entries > EF4_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",
                  ef4_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 = ef4_nic_probe_rx(rx_queue);
        if (rc) {
                kfree(rx_queue->buffer);
                rx_queue->buffer = NULL;
        }

        return rc;
}

static void ef4_init_rx_recycle_ring(struct ef4_nic *efx,
                                     struct ef4_rx_queue *rx_queue)
{
        unsigned int bufs_in_recycle_ring, page_ring_size;

        /* Set the RX recycle ring size */
#ifdef CONFIG_PPC64
        bufs_in_recycle_ring = EF4_RECYCLE_RING_SIZE_IOMMU;
#else
        if (iommu_present(&pci_bus_type))
                bufs_in_recycle_ring = EF4_RECYCLE_RING_SIZE_IOMMU;
        else
                bufs_in_recycle_ring = EF4_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;
}

void ef4_init_rx_queue(struct ef4_rx_queue *rx_queue)
{
        struct ef4_nic *efx = rx_queue->efx;
        unsigned int max_fill, trigger, max_trigger;

        netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
                  "initialising RX queue %d\n", ef4_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;
        ef4_init_rx_recycle_ring(efx, 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 - EF4_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;

        /* Set up RX descriptor ring */
        ef4_nic_init_rx(rx_queue);
}

void ef4_fini_rx_queue(struct ef4_rx_queue *rx_queue)
{
        int i;
        struct ef4_nic *efx = rx_queue->efx;
        struct ef4_rx_buffer *rx_buf;

        netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
                  "shutting down RX queue %d\n", ef4_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 index = i & rx_queue->ptr_mask;
                        rx_buf = ef4_rx_buffer(rx_queue, index);
                        ef4_fini_rx_buffer(rx_queue, rx_buf);
                }
        }

        /* 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 ef4_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;
}

void ef4_remove_rx_queue(struct ef4_rx_queue *rx_queue)
{
        netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
                  "destroying RX queue %d\n", ef4_rx_queue_index(rx_queue));

        ef4_nic_remove_rx(rx_queue);

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


module_param(rx_refill_threshold, uint, 0444);
MODULE_PARM_DESC(rx_refill_threshold,
                 "RX descriptor ring refill threshold (%)");

#ifdef CONFIG_RFS_ACCEL

int ef4_filter_rfs(struct net_device *net_dev, const struct sk_buff *skb,
                   u16 rxq_index, u32 flow_id)
{
        struct ef4_nic *efx = netdev_priv(net_dev);
        struct ef4_channel *channel;
        struct ef4_filter_spec spec;
        struct flow_keys fk;
        int rc;

        if (flow_id == RPS_FLOW_ID_INVALID)
                return -EINVAL;

        if (!skb_flow_dissect_flow_keys(skb, &fk, 0))
                return -EPROTONOSUPPORT;

        if (fk.basic.n_proto != htons(ETH_P_IP) && fk.basic.n_proto != htons(ETH_P_IPV6))
                return -EPROTONOSUPPORT;
        if (fk.control.flags & FLOW_DIS_IS_FRAGMENT)
                return -EPROTONOSUPPORT;

        ef4_filter_init_rx(&spec, EF4_FILTER_PRI_HINT,
                           efx->rx_scatter ? EF4_FILTER_FLAG_RX_SCATTER : 0,
                           rxq_index);
        spec.match_flags =
                EF4_FILTER_MATCH_ETHER_TYPE | EF4_FILTER_MATCH_IP_PROTO |
                EF4_FILTER_MATCH_LOC_HOST | EF4_FILTER_MATCH_LOC_PORT |
                EF4_FILTER_MATCH_REM_HOST | EF4_FILTER_MATCH_REM_PORT;
        spec.ether_type = fk.basic.n_proto;
        spec.ip_proto = fk.basic.ip_proto;

        if (fk.basic.n_proto == htons(ETH_P_IP)) {
                spec.rem_host[0] = fk.addrs.v4addrs.src;
                spec.loc_host[0] = fk.addrs.v4addrs.dst;
        } else {
                memcpy(spec.rem_host, &fk.addrs.v6addrs.src, sizeof(struct in6_addr));
                memcpy(spec.loc_host, &fk.addrs.v6addrs.dst, sizeof(struct in6_addr));
        }

        spec.rem_port = fk.ports.src;
        spec.loc_port = fk.ports.dst;

        rc = efx->type->filter_rfs_insert(efx, &spec);
        if (rc < 0)
                return rc;

        /* Remember this so we can check whether to expire the filter later */
        channel = ef4_get_channel(efx, rxq_index);
        channel->rps_flow_id[rc] = flow_id;
        ++channel->rfs_filters_added;

        if (spec.ether_type == htons(ETH_P_IP))
                netif_info(efx, rx_status, efx->net_dev,
                           "steering %s %pI4:%u:%pI4:%u to queue %u [flow %u filter %d]\n",
                           (spec.ip_proto == IPPROTO_TCP) ? "TCP" : "UDP",
                           spec.rem_host, ntohs(spec.rem_port), spec.loc_host,
                           ntohs(spec.loc_port), rxq_index, flow_id, rc);
        else
                netif_info(efx, rx_status, efx->net_dev,
                           "steering %s [%pI6]:%u:[%pI6]:%u to queue %u [flow %u filter %d]\n",
                           (spec.ip_proto == IPPROTO_TCP) ? "TCP" : "UDP",
                           spec.rem_host, ntohs(spec.rem_port), spec.loc_host,
                           ntohs(spec.loc_port), rxq_index, flow_id, rc);

        return rc;
}

bool __ef4_filter_rfs_expire(struct ef4_nic *efx, unsigned int quota)
{
        bool (*expire_one)(struct ef4_nic *efx, u32 flow_id, unsigned int index);
        unsigned int channel_idx, index, size;
        u32 flow_id;

        if (!spin_trylock_bh(&efx->filter_lock))
                return false;

        expire_one = efx->type->filter_rfs_expire_one;
        channel_idx = efx->rps_expire_channel;
        index = efx->rps_expire_index;
        size = efx->type->max_rx_ip_filters;
        while (quota--) {
                struct ef4_channel *channel = ef4_get_channel(efx, channel_idx);
                flow_id = channel->rps_flow_id[index];

                if (flow_id != RPS_FLOW_ID_INVALID &&
                    expire_one(efx, flow_id, index)) {
                        netif_info(efx, rx_status, efx->net_dev,
                                   "expired filter %d [queue %u flow %u]\n",
                                   index, channel_idx, flow_id);
                        channel->rps_flow_id[index] = RPS_FLOW_ID_INVALID;
                }
                if (++index == size) {
                        if (++channel_idx == efx->n_channels)
                                channel_idx = 0;
                        index = 0;
                }
        }
        efx->rps_expire_channel = channel_idx;
        efx->rps_expire_index = index;

        spin_unlock_bh(&efx->filter_lock);
        return true;
}

#endif /* CONFIG_RFS_ACCEL */

/**
 * ef4_filter_is_mc_recipient - test whether spec is a multicast recipient
 * @spec: Specification to test
 *
 * Return: %true if the specification is a non-drop RX filter that
 * matches a local MAC address I/G bit value of 1 or matches a local
 * IPv4 or IPv6 address value in the respective multicast address
 * range.  Otherwise %false.
 */
bool ef4_filter_is_mc_recipient(const struct ef4_filter_spec *spec)
{
        if (!(spec->flags & EF4_FILTER_FLAG_RX) ||
            spec->dmaq_id == EF4_FILTER_RX_DMAQ_ID_DROP)
                return false;

        if (spec->match_flags &
            (EF4_FILTER_MATCH_LOC_MAC | EF4_FILTER_MATCH_LOC_MAC_IG) &&
            is_multicast_ether_addr(spec->loc_mac))
                return true;

        if ((spec->match_flags &
             (EF4_FILTER_MATCH_ETHER_TYPE | EF4_FILTER_MATCH_LOC_HOST)) ==
            (EF4_FILTER_MATCH_ETHER_TYPE | EF4_FILTER_MATCH_LOC_HOST)) {
                if (spec->ether_type == htons(ETH_P_IP) &&
                    ipv4_is_multicast(spec->loc_host[0]))
                        return true;
                if (spec->ether_type == htons(ETH_P_IPV6) &&
                    ((const u8 *)spec->loc_host)[0] == 0xff)
                        return true;
        }

        return false;
}