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// SPDX-License-Identifier: (GPL-2.0 OR MIT)
/* Google virtual Ethernet (gve) driver
*
* Copyright (C) 2015-2019 Google, Inc.
*/
#include "gve.h"
#include "gve_adminq.h"
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/vmalloc.h>
#include <linux/skbuff.h>
static inline void gve_tx_put_doorbell(struct gve_priv *priv,
struct gve_queue_resources *q_resources,
u32 val)
{
iowrite32be(val, &priv->db_bar2[be32_to_cpu(q_resources->db_index)]);
}
/* gvnic can only transmit from a Registered Segment.
* We copy skb payloads into the registered segment before writing Tx
* descriptors and ringing the Tx doorbell.
*
* gve_tx_fifo_* manages the Registered Segment as a FIFO - clients must
* free allocations in the order they were allocated.
*/
static int gve_tx_fifo_init(struct gve_priv *priv, struct gve_tx_fifo *fifo)
{
fifo->base = vmap(fifo->qpl->pages, fifo->qpl->num_entries, VM_MAP,
PAGE_KERNEL);
if (unlikely(!fifo->base)) {
netif_err(priv, drv, priv->dev, "Failed to vmap fifo, qpl_id = %d\n",
fifo->qpl->id);
return -ENOMEM;
}
fifo->size = fifo->qpl->num_entries * PAGE_SIZE;
atomic_set(&fifo->available, fifo->size);
fifo->head = 0;
return 0;
}
static void gve_tx_fifo_release(struct gve_priv *priv, struct gve_tx_fifo *fifo)
{
WARN(atomic_read(&fifo->available) != fifo->size,
"Releasing non-empty fifo");
vunmap(fifo->base);
}
static int gve_tx_fifo_pad_alloc_one_frag(struct gve_tx_fifo *fifo,
size_t bytes)
{
return (fifo->head + bytes < fifo->size) ? 0 : fifo->size - fifo->head;
}
static bool gve_tx_fifo_can_alloc(struct gve_tx_fifo *fifo, size_t bytes)
{
return (atomic_read(&fifo->available) <= bytes) ? false : true;
}
/* gve_tx_alloc_fifo - Allocate fragment(s) from Tx FIFO
* @fifo: FIFO to allocate from
* @bytes: Allocation size
* @iov: Scatter-gather elements to fill with allocation fragment base/len
*
* Returns number of valid elements in iov[] or negative on error.
*
* Allocations from a given FIFO must be externally synchronized but concurrent
* allocation and frees are allowed.
*/
static int gve_tx_alloc_fifo(struct gve_tx_fifo *fifo, size_t bytes,
struct gve_tx_iovec iov[2])
{
size_t overflow, padding;
u32 aligned_head;
int nfrags = 0;
if (!bytes)
return 0;
/* This check happens before we know how much padding is needed to
* align to a cacheline boundary for the payload, but that is fine,
* because the FIFO head always start aligned, and the FIFO's boundaries
* are aligned, so if there is space for the data, there is space for
* the padding to the next alignment.
*/
WARN(!gve_tx_fifo_can_alloc(fifo, bytes),
"Reached %s when there's not enough space in the fifo", __func__);
nfrags++;
iov[0].iov_offset = fifo->head;
iov[0].iov_len = bytes;
fifo->head += bytes;
if (fifo->head > fifo->size) {
/* If the allocation did not fit in the tail fragment of the
* FIFO, also use the head fragment.
*/
nfrags++;
overflow = fifo->head - fifo->size;
iov[0].iov_len -= overflow;
iov[1].iov_offset = 0; /* Start of fifo*/
iov[1].iov_len = overflow;
fifo->head = overflow;
}
/* Re-align to a cacheline boundary */
aligned_head = L1_CACHE_ALIGN(fifo->head);
padding = aligned_head - fifo->head;
iov[nfrags - 1].iov_padding = padding;
atomic_sub(bytes + padding, &fifo->available);
fifo->head = aligned_head;
if (fifo->head == fifo->size)
fifo->head = 0;
return nfrags;
}
/* gve_tx_free_fifo - Return space to Tx FIFO
* @fifo: FIFO to return fragments to
* @bytes: Bytes to free
*/
static void gve_tx_free_fifo(struct gve_tx_fifo *fifo, size_t bytes)
{
atomic_add(bytes, &fifo->available);
}
static void gve_tx_remove_from_block(struct gve_priv *priv, int queue_idx)
{
struct gve_notify_block *block =
&priv->ntfy_blocks[gve_tx_idx_to_ntfy(priv, queue_idx)];
block->tx = NULL;
}
static int gve_clean_tx_done(struct gve_priv *priv, struct gve_tx_ring *tx,
u32 to_do, bool try_to_wake);
static void gve_tx_free_ring(struct gve_priv *priv, int idx)
{
struct gve_tx_ring *tx = &priv->tx[idx];
struct device *hdev = &priv->pdev->dev;
size_t bytes;
u32 slots;
gve_tx_remove_from_block(priv, idx);
slots = tx->mask + 1;
gve_clean_tx_done(priv, tx, tx->req, false);
netdev_tx_reset_queue(tx->netdev_txq);
dma_free_coherent(hdev, sizeof(*tx->q_resources),
tx->q_resources, tx->q_resources_bus);
tx->q_resources = NULL;
gve_tx_fifo_release(priv, &tx->tx_fifo);
gve_unassign_qpl(priv, tx->tx_fifo.qpl->id);
tx->tx_fifo.qpl = NULL;
bytes = sizeof(*tx->desc) * slots;
dma_free_coherent(hdev, bytes, tx->desc, tx->bus);
tx->desc = NULL;
vfree(tx->info);
tx->info = NULL;
netif_dbg(priv, drv, priv->dev, "freed tx queue %d\n", idx);
}
static void gve_tx_add_to_block(struct gve_priv *priv, int queue_idx)
{
int ntfy_idx = gve_tx_idx_to_ntfy(priv, queue_idx);
struct gve_notify_block *block = &priv->ntfy_blocks[ntfy_idx];
struct gve_tx_ring *tx = &priv->tx[queue_idx];
block->tx = tx;
tx->ntfy_id = ntfy_idx;
}
static int gve_tx_alloc_ring(struct gve_priv *priv, int idx)
{
struct gve_tx_ring *tx = &priv->tx[idx];
struct device *hdev = &priv->pdev->dev;
u32 slots = priv->tx_desc_cnt;
size_t bytes;
/* Make sure everything is zeroed to start */
memset(tx, 0, sizeof(*tx));
tx->q_num = idx;
tx->mask = slots - 1;
/* alloc metadata */
tx->info = vzalloc(sizeof(*tx->info) * slots);
if (!tx->info)
return -ENOMEM;
/* alloc tx queue */
bytes = sizeof(*tx->desc) * slots;
tx->desc = dma_alloc_coherent(hdev, bytes, &tx->bus, GFP_KERNEL);
if (!tx->desc)
goto abort_with_info;
tx->tx_fifo.qpl = gve_assign_tx_qpl(priv);
/* map Tx FIFO */
if (gve_tx_fifo_init(priv, &tx->tx_fifo))
goto abort_with_desc;
tx->q_resources =
dma_alloc_coherent(hdev,
sizeof(*tx->q_resources),
&tx->q_resources_bus,
GFP_KERNEL);
if (!tx->q_resources)
goto abort_with_fifo;
netif_dbg(priv, drv, priv->dev, "tx[%d]->bus=%lx\n", idx,
(unsigned long)tx->bus);
tx->netdev_txq = netdev_get_tx_queue(priv->dev, idx);
gve_tx_add_to_block(priv, idx);
return 0;
abort_with_fifo:
gve_tx_fifo_release(priv, &tx->tx_fifo);
abort_with_desc:
dma_free_coherent(hdev, bytes, tx->desc, tx->bus);
tx->desc = NULL;
abort_with_info:
vfree(tx->info);
tx->info = NULL;
return -ENOMEM;
}
int gve_tx_alloc_rings(struct gve_priv *priv)
{
int err = 0;
int i;
for (i = 0; i < priv->tx_cfg.num_queues; i++) {
err = gve_tx_alloc_ring(priv, i);
if (err) {
netif_err(priv, drv, priv->dev,
"Failed to alloc tx ring=%d: err=%d\n",
i, err);
break;
}
}
/* Unallocate if there was an error */
if (err) {
int j;
for (j = 0; j < i; j++)
gve_tx_free_ring(priv, j);
}
return err;
}
void gve_tx_free_rings(struct gve_priv *priv)
{
int i;
for (i = 0; i < priv->tx_cfg.num_queues; i++)
gve_tx_free_ring(priv, i);
}
/* gve_tx_avail - Calculates the number of slots available in the ring
* @tx: tx ring to check
*
* Returns the number of slots available
*
* The capacity of the queue is mask + 1. We don't need to reserve an entry.
**/
static inline u32 gve_tx_avail(struct gve_tx_ring *tx)
{
return tx->mask + 1 - (tx->req - tx->done);
}
static inline int gve_skb_fifo_bytes_required(struct gve_tx_ring *tx,
struct sk_buff *skb)
{
int pad_bytes, align_hdr_pad;
int bytes;
int hlen;
hlen = skb_is_gso(skb) ? skb_checksum_start_offset(skb) +
tcp_hdrlen(skb) : skb_headlen(skb);
pad_bytes = gve_tx_fifo_pad_alloc_one_frag(&tx->tx_fifo,
hlen);
/* We need to take into account the header alignment padding. */
align_hdr_pad = L1_CACHE_ALIGN(hlen) - hlen;
bytes = align_hdr_pad + pad_bytes + skb->len;
return bytes;
}
/* The most descriptors we could need are 3 - 1 for the headers, 1 for
* the beginning of the payload at the end of the FIFO, and 1 if the
* payload wraps to the beginning of the FIFO.
*/
#define MAX_TX_DESC_NEEDED 3
/* Check if sufficient resources (descriptor ring space, FIFO space) are
* available to transmit the given number of bytes.
*/
static inline bool gve_can_tx(struct gve_tx_ring *tx, int bytes_required)
{
return (gve_tx_avail(tx) >= MAX_TX_DESC_NEEDED &&
gve_tx_fifo_can_alloc(&tx->tx_fifo, bytes_required));
}
/* Stops the queue if the skb cannot be transmitted. */
static int gve_maybe_stop_tx(struct gve_tx_ring *tx, struct sk_buff *skb)
{
int bytes_required;
bytes_required = gve_skb_fifo_bytes_required(tx, skb);
if (likely(gve_can_tx(tx, bytes_required)))
return 0;
/* No space, so stop the queue */
tx->stop_queue++;
netif_tx_stop_queue(tx->netdev_txq);
smp_mb(); /* sync with restarting queue in gve_clean_tx_done() */
/* Now check for resources again, in case gve_clean_tx_done() freed
* resources after we checked and we stopped the queue after
* gve_clean_tx_done() checked.
*
* gve_maybe_stop_tx() gve_clean_tx_done()
* nsegs/can_alloc test failed
* gve_tx_free_fifo()
* if (tx queue stopped)
* netif_tx_queue_wake()
* netif_tx_stop_queue()
* Need to check again for space here!
*/
if (likely(!gve_can_tx(tx, bytes_required)))
return -EBUSY;
netif_tx_start_queue(tx->netdev_txq);
tx->wake_queue++;
return 0;
}
static void gve_tx_fill_pkt_desc(union gve_tx_desc *pkt_desc,
struct sk_buff *skb, bool is_gso,
int l4_hdr_offset, u32 desc_cnt,
u16 hlen, u64 addr)
{
/* l4_hdr_offset and csum_offset are in units of 16-bit words */
if (is_gso) {
pkt_desc->pkt.type_flags = GVE_TXD_TSO | GVE_TXF_L4CSUM;
pkt_desc->pkt.l4_csum_offset = skb->csum_offset >> 1;
pkt_desc->pkt.l4_hdr_offset = l4_hdr_offset >> 1;
} else if (likely(skb->ip_summed == CHECKSUM_PARTIAL)) {
pkt_desc->pkt.type_flags = GVE_TXD_STD | GVE_TXF_L4CSUM;
pkt_desc->pkt.l4_csum_offset = skb->csum_offset >> 1;
pkt_desc->pkt.l4_hdr_offset = l4_hdr_offset >> 1;
} else {
pkt_desc->pkt.type_flags = GVE_TXD_STD;
pkt_desc->pkt.l4_csum_offset = 0;
pkt_desc->pkt.l4_hdr_offset = 0;
}
pkt_desc->pkt.desc_cnt = desc_cnt;
pkt_desc->pkt.len = cpu_to_be16(skb->len);
pkt_desc->pkt.seg_len = cpu_to_be16(hlen);
pkt_desc->pkt.seg_addr = cpu_to_be64(addr);
}
static void gve_tx_fill_seg_desc(union gve_tx_desc *seg_desc,
struct sk_buff *skb, bool is_gso,
u16 len, u64 addr)
{
seg_desc->seg.type_flags = GVE_TXD_SEG;
if (is_gso) {
if (skb_is_gso_v6(skb))
seg_desc->seg.type_flags |= GVE_TXSF_IPV6;
seg_desc->seg.l3_offset = skb_network_offset(skb) >> 1;
seg_desc->seg.mss = cpu_to_be16(skb_shinfo(skb)->gso_size);
}
seg_desc->seg.seg_len = cpu_to_be16(len);
seg_desc->seg.seg_addr = cpu_to_be64(addr);
}
static int gve_tx_add_skb(struct gve_tx_ring *tx, struct sk_buff *skb)
{
int pad_bytes, hlen, hdr_nfrags, payload_nfrags, l4_hdr_offset;
union gve_tx_desc *pkt_desc, *seg_desc;
struct gve_tx_buffer_state *info;
bool is_gso = skb_is_gso(skb);
u32 idx = tx->req & tx->mask;
int payload_iov = 2;
int copy_offset;
u32 next_idx;
int i;
info = &tx->info[idx];
pkt_desc = &tx->desc[idx];
l4_hdr_offset = skb_checksum_start_offset(skb);
/* If the skb is gso, then we want the tcp header in the first segment
* otherwise we want the linear portion of the skb (which will contain
* the checksum because skb->csum_start and skb->csum_offset are given
* relative to skb->head) in the first segment.
*/
hlen = is_gso ? l4_hdr_offset + tcp_hdrlen(skb) :
skb_headlen(skb);
info->skb = skb;
/* We don't want to split the header, so if necessary, pad to the end
* of the fifo and then put the header at the beginning of the fifo.
*/
pad_bytes = gve_tx_fifo_pad_alloc_one_frag(&tx->tx_fifo, hlen);
hdr_nfrags = gve_tx_alloc_fifo(&tx->tx_fifo, hlen + pad_bytes,
&info->iov[0]);
WARN(!hdr_nfrags, "hdr_nfrags should never be 0!");
payload_nfrags = gve_tx_alloc_fifo(&tx->tx_fifo, skb->len - hlen,
&info->iov[payload_iov]);
gve_tx_fill_pkt_desc(pkt_desc, skb, is_gso, l4_hdr_offset,
1 + payload_nfrags, hlen,
info->iov[hdr_nfrags - 1].iov_offset);
skb_copy_bits(skb, 0,
tx->tx_fifo.base + info->iov[hdr_nfrags - 1].iov_offset,
hlen);
copy_offset = hlen;
for (i = payload_iov; i < payload_nfrags + payload_iov; i++) {
next_idx = (tx->req + 1 + i - payload_iov) & tx->mask;
seg_desc = &tx->desc[next_idx];
gve_tx_fill_seg_desc(seg_desc, skb, is_gso,
info->iov[i].iov_len,
info->iov[i].iov_offset);
skb_copy_bits(skb, copy_offset,
tx->tx_fifo.base + info->iov[i].iov_offset,
info->iov[i].iov_len);
copy_offset += info->iov[i].iov_len;
}
return 1 + payload_nfrags;
}
netdev_tx_t gve_tx(struct sk_buff *skb, struct net_device *dev)
{
struct gve_priv *priv = netdev_priv(dev);
struct gve_tx_ring *tx;
int nsegs;
WARN(skb_get_queue_mapping(skb) > priv->tx_cfg.num_queues,
"skb queue index out of range");
tx = &priv->tx[skb_get_queue_mapping(skb)];
if (unlikely(gve_maybe_stop_tx(tx, skb))) {
/* We need to ring the txq doorbell -- we have stopped the Tx
* queue for want of resources, but prior calls to gve_tx()
* may have added descriptors without ringing the doorbell.
*/
/* Ensure tx descs from a prior gve_tx are visible before
* ringing doorbell.
*/
dma_wmb();
gve_tx_put_doorbell(priv, tx->q_resources, tx->req);
return NETDEV_TX_BUSY;
}
nsegs = gve_tx_add_skb(tx, skb);
netdev_tx_sent_queue(tx->netdev_txq, skb->len);
skb_tx_timestamp(skb);
/* give packets to NIC */
tx->req += nsegs;
if (!netif_xmit_stopped(tx->netdev_txq) && netdev_xmit_more())
return NETDEV_TX_OK;
/* Ensure tx descs are visible before ringing doorbell */
dma_wmb();
gve_tx_put_doorbell(priv, tx->q_resources, tx->req);
return NETDEV_TX_OK;
}
#define GVE_TX_START_THRESH PAGE_SIZE
static int gve_clean_tx_done(struct gve_priv *priv, struct gve_tx_ring *tx,
u32 to_do, bool try_to_wake)
{
struct gve_tx_buffer_state *info;
u64 pkts = 0, bytes = 0;
size_t space_freed = 0;
struct sk_buff *skb;
int i, j;
u32 idx;
for (j = 0; j < to_do; j++) {
idx = tx->done & tx->mask;
netif_info(priv, tx_done, priv->dev,
"[%d] %s: idx=%d (req=%u done=%u)\n",
tx->q_num, __func__, idx, tx->req, tx->done);
info = &tx->info[idx];
skb = info->skb;
/* Mark as free */
if (skb) {
info->skb = NULL;
bytes += skb->len;
pkts++;
dev_consume_skb_any(skb);
/* FIFO free */
for (i = 0; i < ARRAY_SIZE(info->iov); i++) {
space_freed += info->iov[i].iov_len +
info->iov[i].iov_padding;
info->iov[i].iov_len = 0;
info->iov[i].iov_padding = 0;
}
}
tx->done++;
}
gve_tx_free_fifo(&tx->tx_fifo, space_freed);
u64_stats_update_begin(&tx->statss);
tx->bytes_done += bytes;
tx->pkt_done += pkts;
u64_stats_update_end(&tx->statss);
netdev_tx_completed_queue(tx->netdev_txq, pkts, bytes);
/* start the queue if we've stopped it */
#ifndef CONFIG_BQL
/* Make sure that the doorbells are synced */
smp_mb();
#endif
if (try_to_wake && netif_tx_queue_stopped(tx->netdev_txq) &&
likely(gve_can_tx(tx, GVE_TX_START_THRESH))) {
tx->wake_queue++;
netif_tx_wake_queue(tx->netdev_txq);
}
return pkts;
}
__be32 gve_tx_load_event_counter(struct gve_priv *priv,
struct gve_tx_ring *tx)
{
u32 counter_index = be32_to_cpu((tx->q_resources->counter_index));
return READ_ONCE(priv->counter_array[counter_index]);
}
bool gve_tx_poll(struct gve_notify_block *block, int budget)
{
struct gve_priv *priv = block->priv;
struct gve_tx_ring *tx = block->tx;
bool repoll = false;
u32 nic_done;
u32 to_do;
/* If budget is 0, do all the work */
if (budget == 0)
budget = INT_MAX;
/* Find out how much work there is to be done */
tx->last_nic_done = gve_tx_load_event_counter(priv, tx);
nic_done = be32_to_cpu(tx->last_nic_done);
if (budget > 0) {
/* Do as much work as we have that the budget will
* allow
*/
to_do = min_t(u32, (nic_done - tx->done), budget);
gve_clean_tx_done(priv, tx, to_do, true);
}
/* If we still have work we want to repoll */
repoll |= (nic_done != tx->done);
return repoll;
}
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