1 files changed, 751 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 000000000..5e11b8236
--- /dev/null
+++ b/drivers/net/ethernet/google/gve/gve_tx.c
@@ -0,0 +1,751 @@
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/* Google virtual Ethernet (gve) driver
+ *
+ * Copyright (C) 2015-2021 Google, Inc.
+ */
+
+#include "gve.h"
+#include "gve_adminq.h"
+#include "gve_utils.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 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, priv->tx_desc_cnt, 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;
+
+	if (!tx->raw_addressing) {
+		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 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));
+	spin_lock_init(&tx->clean_lock);
+	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->raw_addressing = priv->queue_format == GVE_GQI_RDA_FORMAT;
+	tx->dev = &priv->pdev->dev;
+	if (!tx->raw_addressing) {
+		tx->tx_fifo.qpl = gve_assign_tx_qpl(priv);
+		if (!tx->tx_fifo.qpl)
+			goto abort_with_desc;
+		/* map Tx FIFO */
+		if (gve_tx_fifo_init(priv, &tx->tx_fifo))
+			goto abort_with_qpl;
+	}
+
+	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:
+	if (!tx->raw_addressing)
+		gve_tx_fifo_release(priv, &tx->tx_fifo);
+abort_with_qpl:
+	if (!tx->raw_addressing)
+		gve_unassign_qpl(priv, tx->tx_fifo.qpl->id);
+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_gqi(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) :
+				 min_t(int, GVE_GQ_TX_MIN_PKT_DESC_BYTES, skb->len);
+
+	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 is MAX_SKB_FRAGS + 4 :
+ * 1 for each skb frag
+ * 1 for the skb linear portion
+ * 1 for when tcp hdr needs to be in separate descriptor
+ * 1 if the payload wraps to the beginning of the FIFO
+ * 1 for metadata descriptor
+ */
+#define MAX_TX_DESC_NEEDED	(MAX_SKB_FRAGS + 4)
+static void gve_tx_unmap_buf(struct device *dev, struct gve_tx_buffer_state *info)
+{
+	if (info->skb) {
+		dma_unmap_single(dev, dma_unmap_addr(info, dma),
+				 dma_unmap_len(info, len),
+				 DMA_TO_DEVICE);
+		dma_unmap_len_set(info, len, 0);
+	} else {
+		dma_unmap_page(dev, dma_unmap_addr(info, dma),
+			       dma_unmap_len(info, len),
+			       DMA_TO_DEVICE);
+		dma_unmap_len_set(info, len, 0);
+	}
+}
+
+/* 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)
+{
+	bool can_alloc = true;
+
+	if (!tx->raw_addressing)
+		can_alloc = gve_tx_fifo_can_alloc(&tx->tx_fifo, bytes_required);
+
+	return (gve_tx_avail(tx) >= MAX_TX_DESC_NEEDED && can_alloc);
+}
+
+static_assert(NAPI_POLL_WEIGHT >= MAX_TX_DESC_NEEDED);
+
+/* Stops the queue if the skb cannot be transmitted. */
+static int gve_maybe_stop_tx(struct gve_priv *priv, struct gve_tx_ring *tx,
+			     struct sk_buff *skb)
+{
+	int bytes_required = 0;
+	u32 nic_done;
+	u32 to_do;
+	int ret;
+
+	if (!tx->raw_addressing)
+		bytes_required = gve_skb_fifo_bytes_required(tx, skb);
+
+	if (likely(gve_can_tx(tx, bytes_required)))
+		return 0;
+
+	ret = -EBUSY;
+	spin_lock(&tx->clean_lock);
+	nic_done = gve_tx_load_event_counter(priv, tx);
+	to_do = nic_done - tx->done;
+
+	/* Only try to clean if there is hope for TX */
+	if (to_do + gve_tx_avail(tx) >= MAX_TX_DESC_NEEDED) {
+		if (to_do > 0) {
+			to_do = min_t(u32, to_do, NAPI_POLL_WEIGHT);
+			gve_clean_tx_done(priv, tx, to_do, false);
+		}
+		if (likely(gve_can_tx(tx, bytes_required)))
+			ret = 0;
+	}
+	if (ret) {
+		/* No space, so stop the queue */
+		tx->stop_queue++;
+		netif_tx_stop_queue(tx->netdev_txq);
+	}
+	spin_unlock(&tx->clean_lock);
+
+	return ret;
+}
+
+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_mtd_desc(union gve_tx_desc *mtd_desc,
+				 struct sk_buff *skb)
+{
+	BUILD_BUG_ON(sizeof(mtd_desc->mtd) != sizeof(mtd_desc->pkt));
+
+	mtd_desc->mtd.type_flags = GVE_TXD_MTD | GVE_MTD_SUBTYPE_PATH;
+	mtd_desc->mtd.path_state = GVE_MTD_PATH_STATE_DEFAULT |
+				   GVE_MTD_PATH_HASH_L4;
+	mtd_desc->mtd.path_hash = cpu_to_be32(skb->hash);
+	mtd_desc->mtd.reserved0 = 0;
+	mtd_desc->mtd.reserved1 = 0;
+}
+
+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 void gve_dma_sync_for_device(struct device *dev, dma_addr_t *page_buses,
+				    u64 iov_offset, u64 iov_len)
+{
+	u64 last_page = (iov_offset + iov_len - 1) / PAGE_SIZE;
+	u64 first_page = iov_offset / PAGE_SIZE;
+	u64 page;
+
+	for (page = first_page; page <= last_page; page++)
+		dma_sync_single_for_device(dev, page_buses[page], PAGE_SIZE, DMA_TO_DEVICE);
+}
+
+static int gve_tx_add_skb_copy(struct gve_priv *priv, 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;
+	int mtd_desc_nr = !!skb->l4_hash;
+	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 alone in the first segment
+	 * otherwise we want the minimum required by the gVNIC spec.
+	 */
+	hlen = is_gso ? l4_hdr_offset + tcp_hdrlen(skb) :
+			min_t(int, GVE_GQ_TX_MIN_PKT_DESC_BYTES, skb->len);
+
+	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 + mtd_desc_nr + 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);
+	gve_dma_sync_for_device(&priv->pdev->dev, tx->tx_fifo.qpl->page_buses,
+				info->iov[hdr_nfrags - 1].iov_offset,
+				info->iov[hdr_nfrags - 1].iov_len);
+	copy_offset = hlen;
+
+	if (mtd_desc_nr) {
+		next_idx = (tx->req + 1) & tx->mask;
+		gve_tx_fill_mtd_desc(&tx->desc[next_idx], skb);
+	}
+
+	for (i = payload_iov; i < payload_nfrags + payload_iov; i++) {
+		next_idx = (tx->req + 1 + mtd_desc_nr + 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);
+		gve_dma_sync_for_device(&priv->pdev->dev, tx->tx_fifo.qpl->page_buses,
+					info->iov[i].iov_offset,
+					info->iov[i].iov_len);
+		copy_offset += info->iov[i].iov_len;
+	}
+
+	return 1 + mtd_desc_nr + payload_nfrags;
+}
+
+static int gve_tx_add_skb_no_copy(struct gve_priv *priv, struct gve_tx_ring *tx,
+				  struct sk_buff *skb)
+{
+	const struct skb_shared_info *shinfo = skb_shinfo(skb);
+	int hlen, num_descriptors, l4_hdr_offset;
+	union gve_tx_desc *pkt_desc, *mtd_desc, *seg_desc;
+	struct gve_tx_buffer_state *info;
+	int mtd_desc_nr = !!skb->l4_hash;
+	bool is_gso = skb_is_gso(skb);
+	u32 idx = tx->req & tx->mask;
+	u64 addr;
+	u32 len;
+	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 only up to the tcp header in the first segment
+	 * to efficiently replicate on each 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);
+	len = skb_headlen(skb);
+
+	info->skb =  skb;
+
+	addr = dma_map_single(tx->dev, skb->data, len, DMA_TO_DEVICE);
+	if (unlikely(dma_mapping_error(tx->dev, addr))) {
+		tx->dma_mapping_error++;
+		goto drop;
+	}
+	dma_unmap_len_set(info, len, len);
+	dma_unmap_addr_set(info, dma, addr);
+
+	num_descriptors = 1 + shinfo->nr_frags;
+	if (hlen < len)
+		num_descriptors++;
+	if (mtd_desc_nr)
+		num_descriptors++;
+
+	gve_tx_fill_pkt_desc(pkt_desc, skb, is_gso, l4_hdr_offset,
+			     num_descriptors, hlen, addr);
+
+	if (mtd_desc_nr) {
+		idx = (idx + 1) & tx->mask;
+		mtd_desc = &tx->desc[idx];
+		gve_tx_fill_mtd_desc(mtd_desc, skb);
+	}
+
+	if (hlen < len) {
+		/* For gso the rest of the linear portion of the skb needs to
+		 * be in its own descriptor.
+		 */
+		len -= hlen;
+		addr += hlen;
+		idx = (idx + 1) & tx->mask;
+		seg_desc = &tx->desc[idx];
+		gve_tx_fill_seg_desc(seg_desc, skb, is_gso, len, addr);
+	}
+
+	for (i = 0; i < shinfo->nr_frags; i++) {
+		const skb_frag_t *frag = &shinfo->frags[i];
+
+		idx = (idx + 1) & tx->mask;
+		seg_desc = &tx->desc[idx];
+		len = skb_frag_size(frag);
+		addr = skb_frag_dma_map(tx->dev, frag, 0, len, DMA_TO_DEVICE);
+		if (unlikely(dma_mapping_error(tx->dev, addr))) {
+			tx->dma_mapping_error++;
+			goto unmap_drop;
+		}
+		tx->info[idx].skb = NULL;
+		dma_unmap_len_set(&tx->info[idx], len, len);
+		dma_unmap_addr_set(&tx->info[idx], dma, addr);
+
+		gve_tx_fill_seg_desc(seg_desc, skb, is_gso, len, addr);
+	}
+
+	return num_descriptors;
+
+unmap_drop:
+	i += num_descriptors - shinfo->nr_frags;
+	while (i--) {
+		/* Skip metadata descriptor, if set */
+		if (i == 1 && mtd_desc_nr == 1)
+			continue;
+		idx--;
+		gve_tx_unmap_buf(tx->dev, &tx->info[idx & tx->mask]);
+	}
+drop:
+	tx->dropped_pkt++;
+	return 0;
+}
+
+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(priv, 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.
+		 */
+
+		gve_tx_put_doorbell(priv, tx->q_resources, tx->req);
+		return NETDEV_TX_BUSY;
+	}
+	if (tx->raw_addressing)
+		nsegs = gve_tx_add_skb_no_copy(priv, tx, skb);
+	else
+		nsegs = gve_tx_add_skb_copy(priv, tx, skb);
+
+	/* If the packet is getting sent, we need to update the skb */
+	if (nsegs) {
+		netdev_tx_sent_queue(tx->netdev_txq, skb->len);
+		skb_tx_timestamp(skb);
+		tx->req += nsegs;
+	} else {
+		dev_kfree_skb_any(skb);
+	}
+
+	if (!netif_xmit_stopped(tx->netdev_txq) && netdev_xmit_more())
+		return NETDEV_TX_OK;
+
+	/* Give packets to NIC. Even if this packet failed to send the doorbell
+	 * might need to be rung because of xmit_more.
+	 */
+	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;
+
+		/* Unmap the buffer */
+		if (tx->raw_addressing)
+			gve_tx_unmap_buf(tx->dev, info);
+		tx->done++;
+		/* Mark as free */
+		if (skb) {
+			info->skb = NULL;
+			bytes += skb->len;
+			pkts++;
+			dev_consume_skb_any(skb);
+			if (tx->raw_addressing)
+				continue;
+			/* 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;
+			}
+		}
+	}
+
+	if (!tx->raw_addressing)
+		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;
+}
+
+u32 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);
+	__be32 counter = READ_ONCE(priv->counter_array[counter_index]);
+
+	return be32_to_cpu(counter);
+}
+
+bool gve_tx_poll(struct gve_notify_block *block, int budget)
+{
+	struct gve_priv *priv = block->priv;
+	struct gve_tx_ring *tx = block->tx;
+	u32 nic_done;
+	u32 to_do;
+
+	/* If budget is 0, do all the work */
+	if (budget == 0)
+		budget = INT_MAX;
+
+	/* In TX path, it may try to clean completed pkts in order to xmit,
+	 * to avoid cleaning conflict, use spin_lock(), it yields better
+	 * concurrency between xmit/clean than netif's lock.
+	 */
+	spin_lock(&tx->clean_lock);
+	/* Find out how much work there is to be done */
+	nic_done = gve_tx_load_event_counter(priv, tx);
+	to_do = min_t(u32, (nic_done - tx->done), budget);
+	gve_clean_tx_done(priv, tx, to_do, true);
+	spin_unlock(&tx->clean_lock);
+	/* If we still have work we want to repoll */
+	return nic_done != tx->done;
+}
+
+bool gve_tx_clean_pending(struct gve_priv *priv, struct gve_tx_ring *tx)
+{
+	u32 nic_done = gve_tx_load_event_counter(priv, tx);
+
+	return nic_done != tx->done;
+}