1 files changed, 584 insertions, 0 deletions

diff --git a/drivers/net/ethernet/google/gve/gve_tx.c b/drivers/net/ethernet/google/gve/gve_tx.c
new file mode 100644
index 000000000000..778b87b5a06c
--- /dev/null
+++ b/drivers/net/ethernet/google/gve/gve_tx.c
@@ -0,0 +1,584 @@
+// 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;
+}