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net: ena: introduce XDP redirect implementation
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This patch adds a partial support for the XDP_REDIRECT directive which
instructs the driver to pass the packet to an interface specified by the
program. The directive is passed to the driver by calling bpf_redirect()
or bpf_redirect_map() functions from the eBPF program.

To lay the ground for integration with the existing XDP TX
implementation the patch removes the redundant page ref count increase
in ena_xdp_xmit_frame() and then decrease in ena_clean_rx_irq(). Instead
it only DMA unmaps descriptors for which XDP TX or REDIRECT directive
was received.

The XDP Redirect support is still missing .ndo_xdp_xmit function
implementation, which allows to redirect packet to an ENA interface,
which would be added in a later patch.

Signed-off-by: Shay Agroskin <shayagr@amazon.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Shay Agroskin authored and Jakub Kicinski committed Dec 9, 2020
1 parent e8223ee commit a318c70
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Showing 3 changed files with 53 additions and 32 deletions.
1 change: 1 addition & 0 deletions drivers/net/ethernet/amazon/ena/ena_ethtool.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -95,6 +95,7 @@ static const struct ena_stats ena_stats_rx_strings[] = {
ENA_STAT_RX_ENTRY(xdp_pass),
ENA_STAT_RX_ENTRY(xdp_tx),
ENA_STAT_RX_ENTRY(xdp_invalid),
ENA_STAT_RX_ENTRY(xdp_redirect),
};

static const struct ena_stats ena_stats_ena_com_strings[] = {
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83 changes: 51 additions & 32 deletions drivers/net/ethernet/amazon/ena/ena_netdev.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -289,21 +289,17 @@ static int ena_xdp_xmit_frame(struct net_device *dev,
struct ena_com_tx_ctx ena_tx_ctx = {};
struct ena_tx_buffer *tx_info;
struct ena_ring *xdp_ring;
struct page *rx_buff_page;
u16 next_to_use, req_id;
int rc;
void *push_hdr;
u32 push_len;

rx_buff_page = virt_to_page(xdpf->data);

xdp_ring = &adapter->tx_ring[qid];
next_to_use = xdp_ring->next_to_use;
req_id = xdp_ring->free_ids[next_to_use];
tx_info = &xdp_ring->tx_buffer_info[req_id];
tx_info->num_of_bufs = 0;
page_ref_inc(rx_buff_page);
tx_info->xdp_rx_page = rx_buff_page;
tx_info->xdp_rx_page = virt_to_page(xdpf->data);

rc = ena_xdp_tx_map_frame(xdp_ring, tx_info, xdpf, &push_hdr, &push_len);
if (unlikely(rc))
Expand Down Expand Up @@ -335,7 +331,7 @@ static int ena_xdp_xmit_frame(struct net_device *dev,
ena_unmap_tx_buff(xdp_ring, tx_info);
tx_info->xdpf = NULL;
error_drop_packet:
__free_page(tx_info->xdp_rx_page);
xdp_return_frame(xdpf);
return NETDEV_TX_OK;
}

Expand All @@ -354,25 +350,36 @@ static int ena_xdp_execute(struct ena_ring *rx_ring, struct xdp_buff *xdp)

verdict = bpf_prog_run_xdp(xdp_prog, xdp);

if (verdict == XDP_TX) {
switch (verdict) {
case XDP_TX:
xdpf = xdp_convert_buff_to_frame(xdp);
if (unlikely(!xdpf)) {
trace_xdp_exception(rx_ring->netdev, xdp_prog, verdict);
xdp_stat = &rx_ring->rx_stats.xdp_aborted;
} else {
ena_xdp_xmit_frame(rx_ring->netdev, xdpf,
rx_ring->qid + rx_ring->adapter->num_io_queues);
break;
}

xdp_stat = &rx_ring->rx_stats.xdp_tx;
ena_xdp_xmit_frame(rx_ring->netdev, xdpf,
rx_ring->qid + rx_ring->adapter->num_io_queues);
xdp_stat = &rx_ring->rx_stats.xdp_tx;
break;
case XDP_REDIRECT:
if (likely(!xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog))) {
xdp_stat = &rx_ring->rx_stats.xdp_redirect;
break;
}
} else if (unlikely(verdict == XDP_ABORTED)) {
fallthrough;
case XDP_ABORTED:
trace_xdp_exception(rx_ring->netdev, xdp_prog, verdict);
xdp_stat = &rx_ring->rx_stats.xdp_aborted;
} else if (unlikely(verdict == XDP_DROP)) {
break;
case XDP_DROP:
xdp_stat = &rx_ring->rx_stats.xdp_drop;
} else if (unlikely(verdict == XDP_PASS)) {
break;
case XDP_PASS:
xdp_stat = &rx_ring->rx_stats.xdp_pass;
} else {
break;
default:
bpf_warn_invalid_xdp_action(verdict);
xdp_stat = &rx_ring->rx_stats.xdp_invalid;
}
Expand Down Expand Up @@ -958,21 +965,28 @@ static int ena_alloc_rx_page(struct ena_ring *rx_ring,
return 0;
}

static void ena_unmap_rx_buff(struct ena_ring *rx_ring,
struct ena_rx_buffer *rx_info)
{
struct ena_com_buf *ena_buf = &rx_info->ena_buf;

dma_unmap_page(rx_ring->dev, ena_buf->paddr - rx_ring->rx_headroom,
ENA_PAGE_SIZE,
DMA_BIDIRECTIONAL);
}

static void ena_free_rx_page(struct ena_ring *rx_ring,
struct ena_rx_buffer *rx_info)
{
struct page *page = rx_info->page;
struct ena_com_buf *ena_buf = &rx_info->ena_buf;

if (unlikely(!page)) {
netif_warn(rx_ring->adapter, rx_err, rx_ring->netdev,
"Trying to free unallocated buffer\n");
return;
}

dma_unmap_page(rx_ring->dev, ena_buf->paddr - rx_ring->rx_headroom,
ENA_PAGE_SIZE,
DMA_BIDIRECTIONAL);
ena_unmap_rx_buff(rx_ring, rx_info);

__free_page(page);
rx_info->page = NULL;
Expand Down Expand Up @@ -1396,9 +1410,7 @@ static struct sk_buff *ena_rx_skb(struct ena_ring *rx_ring,
return NULL;

do {
dma_unmap_page(rx_ring->dev,
dma_unmap_addr(&rx_info->ena_buf, paddr),
ENA_PAGE_SIZE, DMA_BIDIRECTIONAL);
ena_unmap_rx_buff(rx_ring, rx_info);

skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, rx_info->page,
rx_info->page_offset, len, ENA_PAGE_SIZE);
Expand Down Expand Up @@ -1556,6 +1568,7 @@ static int ena_clean_rx_irq(struct ena_ring *rx_ring, struct napi_struct *napi,
struct sk_buff *skb;
int refill_required;
struct xdp_buff xdp;
int xdp_flags = 0;
int total_len = 0;
int xdp_verdict;
int rc = 0;
Expand Down Expand Up @@ -1603,22 +1616,25 @@ static int ena_clean_rx_irq(struct ena_ring *rx_ring, struct napi_struct *napi,
&next_to_clean);

if (unlikely(!skb)) {
/* The page might not actually be freed here since the
* page reference count is incremented in
* ena_xdp_xmit_frame(), and it will be decreased only
* when send completion was received from the device
*/
if (xdp_verdict == XDP_TX)
ena_free_rx_page(rx_ring,
&rx_ring->rx_buffer_info[rx_ring->ena_bufs[0].req_id]);
for (i = 0; i < ena_rx_ctx.descs; i++) {
rx_ring->free_ids[next_to_clean] =
rx_ring->ena_bufs[i].req_id;
int req_id = rx_ring->ena_bufs[i].req_id;

rx_ring->free_ids[next_to_clean] = req_id;
next_to_clean =
ENA_RX_RING_IDX_NEXT(next_to_clean,
rx_ring->ring_size);

/* Packets was passed for transmission, unmap it
* from RX side.
*/
if (xdp_verdict == XDP_TX || xdp_verdict == XDP_REDIRECT) {
ena_unmap_rx_buff(rx_ring,
&rx_ring->rx_buffer_info[req_id]);
rx_ring->rx_buffer_info[req_id].page = NULL;
}
}
if (xdp_verdict != XDP_PASS) {
xdp_flags |= xdp_verdict;
res_budget--;
continue;
}
Expand Down Expand Up @@ -1664,6 +1680,9 @@ static int ena_clean_rx_irq(struct ena_ring *rx_ring, struct napi_struct *napi,
ena_refill_rx_bufs(rx_ring, refill_required);
}

if (xdp_flags & XDP_REDIRECT)
xdp_do_flush_map();

return work_done;

error:
Expand Down
1 change: 1 addition & 0 deletions drivers/net/ethernet/amazon/ena/ena_netdev.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -239,6 +239,7 @@ struct ena_stats_rx {
u64 xdp_pass;
u64 xdp_tx;
u64 xdp_invalid;
u64 xdp_redirect;
};

struct ena_ring {
Expand Down

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