xref: /openbmc/linux/drivers/net/ethernet/sun/sunvnet_common.c (revision d9ffa069)

// SPDX-License-Identifier: GPL-2.0
/* sunvnet.c: Sun LDOM Virtual Network Driver.
 *
 * Copyright (C) 2007, 2008 David S. Miller <davem@davemloft.net>
 * Copyright (C) 2016-2017 Oracle. All rights reserved.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/ethtool.h>
#include <linux/etherdevice.h>
#include <linux/mutex.h>
#include <linux/highmem.h>
#include <linux/if_vlan.h>
#define CREATE_TRACE_POINTS
#include <trace/events/sunvnet.h>

#if IS_ENABLED(CONFIG_IPV6)
#include <linux/icmpv6.h>
#endif

#include <net/ip.h>
#include <net/gso.h>
#include <net/icmp.h>
#include <net/route.h>

#include <asm/vio.h>
#include <asm/ldc.h>

#include "sunvnet_common.h"

/* Heuristic for the number of times to exponentially backoff and
 * retry sending an LDC trigger when EAGAIN is encountered
 */
#define	VNET_MAX_RETRIES	10

MODULE_AUTHOR("David S. Miller (davem@davemloft.net)");
MODULE_DESCRIPTION("Sun LDOM virtual network support library");
MODULE_LICENSE("GPL");
MODULE_VERSION("1.1");

static int __vnet_tx_trigger(struct vnet_port *port, u32 start);

static inline u32 vnet_tx_dring_avail(struct vio_dring_state *dr)
{
	return vio_dring_avail(dr, VNET_TX_RING_SIZE);
}

static int vnet_handle_unknown(struct vnet_port *port, void *arg)
{
	struct vio_msg_tag *pkt = arg;

	pr_err("Received unknown msg [%02x:%02x:%04x:%08x]\n",
	       pkt->type, pkt->stype, pkt->stype_env, pkt->sid);
	pr_err("Resetting connection\n");

	ldc_disconnect(port->vio.lp);

	return -ECONNRESET;
}

static int vnet_port_alloc_tx_ring(struct vnet_port *port);

int sunvnet_send_attr_common(struct vio_driver_state *vio)
{
	struct vnet_port *port = to_vnet_port(vio);
	struct net_device *dev = VNET_PORT_TO_NET_DEVICE(port);
	struct vio_net_attr_info pkt;
	int framelen = ETH_FRAME_LEN;
	int i, err;

	err = vnet_port_alloc_tx_ring(to_vnet_port(vio));
	if (err)
		return err;

	memset(&pkt, 0, sizeof(pkt));
	pkt.tag.type = VIO_TYPE_CTRL;
	pkt.tag.stype = VIO_SUBTYPE_INFO;
	pkt.tag.stype_env = VIO_ATTR_INFO;
	pkt.tag.sid = vio_send_sid(vio);
	if (vio_version_before(vio, 1, 2))
		pkt.xfer_mode = VIO_DRING_MODE;
	else
		pkt.xfer_mode = VIO_NEW_DRING_MODE;
	pkt.addr_type = VNET_ADDR_ETHERMAC;
	pkt.ack_freq = 0;
	for (i = 0; i < 6; i++)
		pkt.addr |= (u64)dev->dev_addr[i] << ((5 - i) * 8);
	if (vio_version_after(vio, 1, 3)) {
		if (port->rmtu) {
			port->rmtu = min(VNET_MAXPACKET, port->rmtu);
			pkt.mtu = port->rmtu;
		} else {
			port->rmtu = VNET_MAXPACKET;
			pkt.mtu = port->rmtu;
		}
		if (vio_version_after_eq(vio, 1, 6))
			pkt.options = VIO_TX_DRING;
	} else if (vio_version_before(vio, 1, 3)) {
		pkt.mtu = framelen;
	} else { /* v1.3 */
		pkt.mtu = framelen + VLAN_HLEN;
	}

	pkt.cflags = 0;
	if (vio_version_after_eq(vio, 1, 7) && port->tso) {
		pkt.cflags |= VNET_LSO_IPV4_CAPAB;
		if (!port->tsolen)
			port->tsolen = VNET_MAXTSO;
		pkt.ipv4_lso_maxlen = port->tsolen;
	}

	pkt.plnk_updt = PHYSLINK_UPDATE_NONE;

	viodbg(HS, "SEND NET ATTR xmode[0x%x] atype[0x%x] addr[%llx] "
	       "ackfreq[%u] plnk_updt[0x%02x] opts[0x%02x] mtu[%llu] "
	       "cflags[0x%04x] lso_max[%u]\n",
	       pkt.xfer_mode, pkt.addr_type,
	       (unsigned long long)pkt.addr,
	       pkt.ack_freq, pkt.plnk_updt, pkt.options,
	       (unsigned long long)pkt.mtu, pkt.cflags, pkt.ipv4_lso_maxlen);

	return vio_ldc_send(vio, &pkt, sizeof(pkt));
}
EXPORT_SYMBOL_GPL(sunvnet_send_attr_common);

static int handle_attr_info(struct vio_driver_state *vio,
			    struct vio_net_attr_info *pkt)
{
	struct vnet_port *port = to_vnet_port(vio);
	u64	localmtu;
	u8	xfer_mode;

	viodbg(HS, "GOT NET ATTR xmode[0x%x] atype[0x%x] addr[%llx] "
	       "ackfreq[%u] plnk_updt[0x%02x] opts[0x%02x] mtu[%llu] "
	       " (rmtu[%llu]) cflags[0x%04x] lso_max[%u]\n",
	       pkt->xfer_mode, pkt->addr_type,
	       (unsigned long long)pkt->addr,
	       pkt->ack_freq, pkt->plnk_updt, pkt->options,
	       (unsigned long long)pkt->mtu, port->rmtu, pkt->cflags,
	       pkt->ipv4_lso_maxlen);

	pkt->tag.sid = vio_send_sid(vio);

	xfer_mode = pkt->xfer_mode;
	/* for version < 1.2, VIO_DRING_MODE = 0x3 and no bitmask */
	if (vio_version_before(vio, 1, 2) && xfer_mode == VIO_DRING_MODE)
		xfer_mode = VIO_NEW_DRING_MODE;

	/* MTU negotiation:
	 *	< v1.3 - ETH_FRAME_LEN exactly
	 *	> v1.3 - MIN(pkt.mtu, VNET_MAXPACKET, port->rmtu) and change
	 *			pkt->mtu for ACK
	 *	= v1.3 - ETH_FRAME_LEN + VLAN_HLEN exactly
	 */
	if (vio_version_before(vio, 1, 3)) {
		localmtu = ETH_FRAME_LEN;
	} else if (vio_version_after(vio, 1, 3)) {
		localmtu = port->rmtu ? port->rmtu : VNET_MAXPACKET;
		localmtu = min(pkt->mtu, localmtu);
		pkt->mtu = localmtu;
	} else { /* v1.3 */
		localmtu = ETH_FRAME_LEN + VLAN_HLEN;
	}
	port->rmtu = localmtu;

	/* LSO negotiation */
	if (vio_version_after_eq(vio, 1, 7))
		port->tso &= !!(pkt->cflags & VNET_LSO_IPV4_CAPAB);
	else
		port->tso = false;
	if (port->tso) {
		if (!port->tsolen)
			port->tsolen = VNET_MAXTSO;
		port->tsolen = min(port->tsolen, pkt->ipv4_lso_maxlen);
		if (port->tsolen < VNET_MINTSO) {
			port->tso = false;
			port->tsolen = 0;
			pkt->cflags &= ~VNET_LSO_IPV4_CAPAB;
		}
		pkt->ipv4_lso_maxlen = port->tsolen;
	} else {
		pkt->cflags &= ~VNET_LSO_IPV4_CAPAB;
		pkt->ipv4_lso_maxlen = 0;
		port->tsolen = 0;
	}

	/* for version >= 1.6, ACK packet mode we support */
	if (vio_version_after_eq(vio, 1, 6)) {
		pkt->xfer_mode = VIO_NEW_DRING_MODE;
		pkt->options = VIO_TX_DRING;
	}

	if (!(xfer_mode | VIO_NEW_DRING_MODE) ||
	    pkt->addr_type != VNET_ADDR_ETHERMAC ||
	    pkt->mtu != localmtu) {
		viodbg(HS, "SEND NET ATTR NACK\n");

		pkt->tag.stype = VIO_SUBTYPE_NACK;

		(void)vio_ldc_send(vio, pkt, sizeof(*pkt));

		return -ECONNRESET;
	}

	viodbg(HS, "SEND NET ATTR ACK xmode[0x%x] atype[0x%x] "
	       "addr[%llx] ackfreq[%u] plnk_updt[0x%02x] opts[0x%02x] "
	       "mtu[%llu] (rmtu[%llu]) cflags[0x%04x] lso_max[%u]\n",
	       pkt->xfer_mode, pkt->addr_type,
	       (unsigned long long)pkt->addr,
	       pkt->ack_freq, pkt->plnk_updt, pkt->options,
	       (unsigned long long)pkt->mtu, port->rmtu, pkt->cflags,
	       pkt->ipv4_lso_maxlen);

	pkt->tag.stype = VIO_SUBTYPE_ACK;

	return vio_ldc_send(vio, pkt, sizeof(*pkt));
}

static int handle_attr_ack(struct vio_driver_state *vio,
			   struct vio_net_attr_info *pkt)
{
	viodbg(HS, "GOT NET ATTR ACK\n");

	return 0;
}

static int handle_attr_nack(struct vio_driver_state *vio,
			    struct vio_net_attr_info *pkt)
{
	viodbg(HS, "GOT NET ATTR NACK\n");

	return -ECONNRESET;
}

int sunvnet_handle_attr_common(struct vio_driver_state *vio, void *arg)
{
	struct vio_net_attr_info *pkt = arg;

	switch (pkt->tag.stype) {
	case VIO_SUBTYPE_INFO:
		return handle_attr_info(vio, pkt);

	case VIO_SUBTYPE_ACK:
		return handle_attr_ack(vio, pkt);

	case VIO_SUBTYPE_NACK:
		return handle_attr_nack(vio, pkt);

	default:
		return -ECONNRESET;
	}
}
EXPORT_SYMBOL_GPL(sunvnet_handle_attr_common);

void sunvnet_handshake_complete_common(struct vio_driver_state *vio)
{
	struct vio_dring_state *dr;

	dr = &vio->drings[VIO_DRIVER_RX_RING];
	dr->rcv_nxt = 1;
	dr->snd_nxt = 1;

	dr = &vio->drings[VIO_DRIVER_TX_RING];
	dr->rcv_nxt = 1;
	dr->snd_nxt = 1;
}
EXPORT_SYMBOL_GPL(sunvnet_handshake_complete_common);

/* The hypervisor interface that implements copying to/from imported
 * memory from another domain requires that copies are done to 8-byte
 * aligned buffers, and that the lengths of such copies are also 8-byte
 * multiples.
 *
 * So we align skb->data to an 8-byte multiple and pad-out the data
 * area so we can round the copy length up to the next multiple of
 * 8 for the copy.
 *
 * The transmitter puts the actual start of the packet 6 bytes into
 * the buffer it sends over, so that the IP headers after the ethernet
 * header are aligned properly.  These 6 bytes are not in the descriptor
 * length, they are simply implied.  This offset is represented using
 * the VNET_PACKET_SKIP macro.
 */
static struct sk_buff *alloc_and_align_skb(struct net_device *dev,
					   unsigned int len)
{
	struct sk_buff *skb;
	unsigned long addr, off;

	skb = netdev_alloc_skb(dev, len + VNET_PACKET_SKIP + 8 + 8);
	if (unlikely(!skb))
		return NULL;

	addr = (unsigned long)skb->data;
	off = ((addr + 7UL) & ~7UL) - addr;
	if (off)
		skb_reserve(skb, off);

	return skb;
}

static inline void vnet_fullcsum_ipv4(struct sk_buff *skb)
{
	struct iphdr *iph = ip_hdr(skb);
	int offset = skb_transport_offset(skb);

	if (skb->protocol != htons(ETH_P_IP))
		return;
	if (iph->protocol != IPPROTO_TCP &&
	    iph->protocol != IPPROTO_UDP)
		return;
	skb->ip_summed = CHECKSUM_NONE;
	skb->csum_level = 1;
	skb->csum = 0;
	if (iph->protocol == IPPROTO_TCP) {
		struct tcphdr *ptcp = tcp_hdr(skb);

		ptcp->check = 0;
		skb->csum = skb_checksum(skb, offset, skb->len - offset, 0);
		ptcp->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
						skb->len - offset, IPPROTO_TCP,
						skb->csum);
	} else if (iph->protocol == IPPROTO_UDP) {
		struct udphdr *pudp = udp_hdr(skb);

		pudp->check = 0;
		skb->csum = skb_checksum(skb, offset, skb->len - offset, 0);
		pudp->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
						skb->len - offset, IPPROTO_UDP,
						skb->csum);
	}
}

#if IS_ENABLED(CONFIG_IPV6)
static inline void vnet_fullcsum_ipv6(struct sk_buff *skb)
{
	struct ipv6hdr *ip6h = ipv6_hdr(skb);
	int offset = skb_transport_offset(skb);

	if (skb->protocol != htons(ETH_P_IPV6))
		return;
	if (ip6h->nexthdr != IPPROTO_TCP &&
	    ip6h->nexthdr != IPPROTO_UDP)
		return;
	skb->ip_summed = CHECKSUM_NONE;
	skb->csum_level = 1;
	skb->csum = 0;
	if (ip6h->nexthdr == IPPROTO_TCP) {
		struct tcphdr *ptcp = tcp_hdr(skb);

		ptcp->check = 0;
		skb->csum = skb_checksum(skb, offset, skb->len - offset, 0);
		ptcp->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
					      skb->len - offset, IPPROTO_TCP,
					      skb->csum);
	} else if (ip6h->nexthdr == IPPROTO_UDP) {
		struct udphdr *pudp = udp_hdr(skb);

		pudp->check = 0;
		skb->csum = skb_checksum(skb, offset, skb->len - offset, 0);
		pudp->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
					      skb->len - offset, IPPROTO_UDP,
					      skb->csum);
	}
}
#endif

static int vnet_rx_one(struct vnet_port *port, struct vio_net_desc *desc)
{
	struct net_device *dev = VNET_PORT_TO_NET_DEVICE(port);
	unsigned int len = desc->size;
	unsigned int copy_len;
	struct sk_buff *skb;
	int maxlen;
	int err;

	err = -EMSGSIZE;
	if (port->tso && port->tsolen > port->rmtu)
		maxlen = port->tsolen;
	else
		maxlen = port->rmtu;
	if (unlikely(len < ETH_ZLEN || len > maxlen)) {
		dev->stats.rx_length_errors++;
		goto out_dropped;
	}

	skb = alloc_and_align_skb(dev, len);
	err = -ENOMEM;
	if (unlikely(!skb)) {
		dev->stats.rx_missed_errors++;
		goto out_dropped;
	}

	copy_len = (len + VNET_PACKET_SKIP + 7U) & ~7U;
	skb_put(skb, copy_len);
	err = ldc_copy(port->vio.lp, LDC_COPY_IN,
		       skb->data, copy_len, 0,
		       desc->cookies, desc->ncookies);
	if (unlikely(err < 0)) {
		dev->stats.rx_frame_errors++;
		goto out_free_skb;
	}

	skb_pull(skb, VNET_PACKET_SKIP);
	skb_trim(skb, len);
	skb->protocol = eth_type_trans(skb, dev);

	if (vio_version_after_eq(&port->vio, 1, 8)) {
		struct vio_net_dext *dext = vio_net_ext(desc);

		skb_reset_network_header(skb);

		if (dext->flags & VNET_PKT_HCK_IPV4_HDRCKSUM) {
			if (skb->protocol == ETH_P_IP) {
				struct iphdr *iph = ip_hdr(skb);

				iph->check = 0;
				ip_send_check(iph);
			}
		}
		if ((dext->flags & VNET_PKT_HCK_FULLCKSUM) &&
		    skb->ip_summed == CHECKSUM_NONE) {
			if (skb->protocol == htons(ETH_P_IP)) {
				struct iphdr *iph = ip_hdr(skb);
				int ihl = iph->ihl * 4;

				skb_set_transport_header(skb, ihl);
				vnet_fullcsum_ipv4(skb);
#if IS_ENABLED(CONFIG_IPV6)
			} else if (skb->protocol == htons(ETH_P_IPV6)) {
				skb_set_transport_header(skb,
							 sizeof(struct ipv6hdr));
				vnet_fullcsum_ipv6(skb);
#endif
			}
		}
		if (dext->flags & VNET_PKT_HCK_IPV4_HDRCKSUM_OK) {
			skb->ip_summed = CHECKSUM_PARTIAL;
			skb->csum_level = 0;
			if (dext->flags & VNET_PKT_HCK_FULLCKSUM_OK)
				skb->csum_level = 1;
		}
	}

	skb->ip_summed = port->switch_port ? CHECKSUM_NONE : CHECKSUM_PARTIAL;

	if (unlikely(is_multicast_ether_addr(eth_hdr(skb)->h_dest)))
		dev->stats.multicast++;
	dev->stats.rx_packets++;
	dev->stats.rx_bytes += len;
	port->stats.rx_packets++;
	port->stats.rx_bytes += len;
	napi_gro_receive(&port->napi, skb);
	return 0;

out_free_skb:
	kfree_skb(skb);

out_dropped:
	dev->stats.rx_dropped++;
	return err;
}

static int vnet_send_ack(struct vnet_port *port, struct vio_dring_state *dr,
			 u32 start, u32 end, u8 vio_dring_state)
{
	struct vio_dring_data hdr = {
		.tag = {
			.type		= VIO_TYPE_DATA,
			.stype		= VIO_SUBTYPE_ACK,
			.stype_env	= VIO_DRING_DATA,
			.sid		= vio_send_sid(&port->vio),
		},
		.dring_ident		= dr->ident,
		.start_idx		= start,
		.end_idx		= end,
		.state			= vio_dring_state,
	};
	int err, delay;
	int retries = 0;

	hdr.seq = dr->snd_nxt;
	delay = 1;
	do {
		err = vio_ldc_send(&port->vio, &hdr, sizeof(hdr));
		if (err > 0) {
			dr->snd_nxt++;
			break;
		}
		udelay(delay);
		if ((delay <<= 1) > 128)
			delay = 128;
		if (retries++ > VNET_MAX_RETRIES) {
			pr_info("ECONNRESET %x:%x:%x:%x:%x:%x\n",
				port->raddr[0], port->raddr[1],
				port->raddr[2], port->raddr[3],
				port->raddr[4], port->raddr[5]);
			break;
		}
	} while (err == -EAGAIN);

	if (err <= 0 && vio_dring_state == VIO_DRING_STOPPED) {
		port->stop_rx_idx = end;
		port->stop_rx = true;
	} else {
		port->stop_rx_idx = 0;
		port->stop_rx = false;
	}

	return err;
}

static struct vio_net_desc *get_rx_desc(struct vnet_port *port,
					struct vio_dring_state *dr,
					u32 index)
{
	struct vio_net_desc *desc = port->vio.desc_buf;
	int err;

	err = ldc_get_dring_entry(port->vio.lp, desc, dr->entry_size,
				  (index * dr->entry_size),
				  dr->cookies, dr->ncookies);
	if (err < 0)
		return ERR_PTR(err);

	return desc;
}

static int put_rx_desc(struct vnet_port *port,
		       struct vio_dring_state *dr,
		       struct vio_net_desc *desc,
		       u32 index)
{
	int err;

	err = ldc_put_dring_entry(port->vio.lp, desc, dr->entry_size,
				  (index * dr->entry_size),
				  dr->cookies, dr->ncookies);
	if (err < 0)
		return err;

	return 0;
}

static int vnet_walk_rx_one(struct vnet_port *port,
			    struct vio_dring_state *dr,
			    u32 index, int *needs_ack)
{
	struct vio_net_desc *desc = get_rx_desc(port, dr, index);
	struct vio_driver_state *vio = &port->vio;
	int err;

	BUG_ON(!desc);
	if (IS_ERR(desc))
		return PTR_ERR(desc);

	if (desc->hdr.state != VIO_DESC_READY)
		return 1;

	dma_rmb();

	viodbg(DATA, "vio_walk_rx_one desc[%02x:%02x:%08x:%08x:%llx:%llx]\n",
	       desc->hdr.state, desc->hdr.ack,
	       desc->size, desc->ncookies,
	       desc->cookies[0].cookie_addr,
	       desc->cookies[0].cookie_size);

	err = vnet_rx_one(port, desc);
	if (err == -ECONNRESET)
		return err;
	trace_vnet_rx_one(port->vio._local_sid, port->vio._peer_sid,
			  index, desc->hdr.ack);
	desc->hdr.state = VIO_DESC_DONE;
	err = put_rx_desc(port, dr, desc, index);
	if (err < 0)
		return err;
	*needs_ack = desc->hdr.ack;
	return 0;
}

static int vnet_walk_rx(struct vnet_port *port, struct vio_dring_state *dr,
			u32 start, u32 end, int *npkts, int budget)
{
	struct vio_driver_state *vio = &port->vio;
	int ack_start = -1, ack_end = -1;
	bool send_ack = true;

	end = (end == (u32)-1) ? vio_dring_prev(dr, start)
			       : vio_dring_next(dr, end);

	viodbg(DATA, "vnet_walk_rx start[%08x] end[%08x]\n", start, end);

	while (start != end) {
		int ack = 0, err = vnet_walk_rx_one(port, dr, start, &ack);

		if (err == -ECONNRESET)
			return err;
		if (err != 0)
			break;
		(*npkts)++;
		if (ack_start == -1)
			ack_start = start;
		ack_end = start;
		start = vio_dring_next(dr, start);
		if (ack && start != end) {
			err = vnet_send_ack(port, dr, ack_start, ack_end,
					    VIO_DRING_ACTIVE);
			if (err == -ECONNRESET)
				return err;
			ack_start = -1;
		}
		if ((*npkts) >= budget) {
			send_ack = false;
			break;
		}
	}
	if (unlikely(ack_start == -1)) {
		ack_end = vio_dring_prev(dr, start);
		ack_start = ack_end;
	}
	if (send_ack) {
		port->napi_resume = false;
		trace_vnet_tx_send_stopped_ack(port->vio._local_sid,
					       port->vio._peer_sid,
					       ack_end, *npkts);
		return vnet_send_ack(port, dr, ack_start, ack_end,
				     VIO_DRING_STOPPED);
	} else  {
		trace_vnet_tx_defer_stopped_ack(port->vio._local_sid,
						port->vio._peer_sid,
						ack_end, *npkts);
		port->napi_resume = true;
		port->napi_stop_idx = ack_end;
		return 1;
	}
}

static int vnet_rx(struct vnet_port *port, void *msgbuf, int *npkts,
		   int budget)
{
	struct vio_dring_data *pkt = msgbuf;
	struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_RX_RING];
	struct vio_driver_state *vio = &port->vio;

	viodbg(DATA, "vnet_rx stype_env[%04x] seq[%016llx] rcv_nxt[%016llx]\n",
	       pkt->tag.stype_env, pkt->seq, dr->rcv_nxt);

	if (unlikely(pkt->tag.stype_env != VIO_DRING_DATA))
		return 0;
	if (unlikely(pkt->seq != dr->rcv_nxt)) {
		pr_err("RX out of sequence seq[0x%llx] rcv_nxt[0x%llx]\n",
		       pkt->seq, dr->rcv_nxt);
		return 0;
	}

	if (!port->napi_resume)
		dr->rcv_nxt++;

	/* XXX Validate pkt->start_idx and pkt->end_idx XXX */

	return vnet_walk_rx(port, dr, pkt->start_idx, pkt->end_idx,
			    npkts, budget);
}

static int idx_is_pending(struct vio_dring_state *dr, u32 end)
{
	u32 idx = dr->cons;
	int found = 0;

	while (idx != dr->prod) {
		if (idx == end) {
			found = 1;
			break;
		}
		idx = vio_dring_next(dr, idx);
	}
	return found;
}

static int vnet_ack(struct vnet_port *port, void *msgbuf)
{
	struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
	struct vio_dring_data *pkt = msgbuf;
	struct net_device *dev;
	u32 end;
	struct vio_net_desc *desc;
	struct netdev_queue *txq;

	if (unlikely(pkt->tag.stype_env != VIO_DRING_DATA))
		return 0;

	end = pkt->end_idx;
	dev = VNET_PORT_TO_NET_DEVICE(port);
	netif_tx_lock(dev);
	if (unlikely(!idx_is_pending(dr, end))) {
		netif_tx_unlock(dev);
		return 0;
	}

	/* sync for race conditions with vnet_start_xmit() and tell xmit it
	 * is time to send a trigger.
	 */
	trace_vnet_rx_stopped_ack(port->vio._local_sid,
				  port->vio._peer_sid, end);
	dr->cons = vio_dring_next(dr, end);
	desc = vio_dring_entry(dr, dr->cons);
	if (desc->hdr.state == VIO_DESC_READY && !port->start_cons) {
		/* vnet_start_xmit() just populated this dring but missed
		 * sending the "start" LDC message to the consumer.
		 * Send a "start" trigger on its behalf.
		 */
		if (__vnet_tx_trigger(port, dr->cons) > 0)
			port->start_cons = false;
		else
			port->start_cons = true;
	} else {
		port->start_cons = true;
	}
	netif_tx_unlock(dev);

	txq = netdev_get_tx_queue(dev, port->q_index);
	if (unlikely(netif_tx_queue_stopped(txq) &&
		     vnet_tx_dring_avail(dr) >= VNET_TX_WAKEUP_THRESH(dr)))
		return 1;

	return 0;
}

static int vnet_nack(struct vnet_port *port, void *msgbuf)
{
	/* XXX just reset or similar XXX */
	return 0;
}

static int handle_mcast(struct vnet_port *port, void *msgbuf)
{
	struct vio_net_mcast_info *pkt = msgbuf;
	struct net_device *dev = VNET_PORT_TO_NET_DEVICE(port);

	if (pkt->tag.stype != VIO_SUBTYPE_ACK)
		pr_err("%s: Got unexpected MCAST reply [%02x:%02x:%04x:%08x]\n",
		       dev->name,
		       pkt->tag.type,
		       pkt->tag.stype,
		       pkt->tag.stype_env,
		       pkt->tag.sid);

	return 0;
}

/* If the queue is stopped, wake it up so that we'll
 * send out another START message at the next TX.
 */
static void maybe_tx_wakeup(struct vnet_port *port)
{
	struct netdev_queue *txq;

	txq = netdev_get_tx_queue(VNET_PORT_TO_NET_DEVICE(port),
				  port->q_index);
	__netif_tx_lock(txq, smp_processor_id());
	if (likely(netif_tx_queue_stopped(txq)))
		netif_tx_wake_queue(txq);
	__netif_tx_unlock(txq);
}

bool sunvnet_port_is_up_common(struct vnet_port *vnet)
{
	struct vio_driver_state *vio = &vnet->vio;

	return !!(vio->hs_state & VIO_HS_COMPLETE);
}
EXPORT_SYMBOL_GPL(sunvnet_port_is_up_common);

static int vnet_event_napi(struct vnet_port *port, int budget)
{
	struct net_device *dev = VNET_PORT_TO_NET_DEVICE(port);
	struct vio_driver_state *vio = &port->vio;
	int tx_wakeup, err;
	int npkts = 0;

	/* we don't expect any other bits */
	BUG_ON(port->rx_event & ~(LDC_EVENT_DATA_READY |
				  LDC_EVENT_RESET |
				  LDC_EVENT_UP));

	/* RESET takes precedent over any other event */
	if (port->rx_event & LDC_EVENT_RESET) {
		/* a link went down */

		if (port->vsw == 1) {
			netif_tx_stop_all_queues(dev);
			netif_carrier_off(dev);
		}

		vio_link_state_change(vio, LDC_EVENT_RESET);
		vnet_port_reset(port);
		vio_port_up(vio);

		/* If the device is running but its tx queue was
		 * stopped (due to flow control), restart it.
		 * This is necessary since vnet_port_reset()
		 * clears the tx drings and thus we may never get
		 * back a VIO_TYPE_DATA ACK packet - which is
		 * the normal mechanism to restart the tx queue.
		 */
		if (netif_running(dev))
			maybe_tx_wakeup(port);

		port->rx_event = 0;
		port->stats.event_reset++;
		return 0;
	}

	if (port->rx_event & LDC_EVENT_UP) {
		/* a link came up */

		if (port->vsw == 1) {
			netif_carrier_on(port->dev);
			netif_tx_start_all_queues(port->dev);
		}

		vio_link_state_change(vio, LDC_EVENT_UP);
		port->rx_event = 0;
		port->stats.event_up++;
		return 0;
	}

	err = 0;
	tx_wakeup = 0;
	while (1) {
		union {
			struct vio_msg_tag tag;
			u64 raw[8];
		} msgbuf;

		if (port->napi_resume) {
			struct vio_dring_data *pkt =
				(struct vio_dring_data *)&msgbuf;
			struct vio_dring_state *dr =
				&port->vio.drings[VIO_DRIVER_RX_RING];

			pkt->tag.type = VIO_TYPE_DATA;
			pkt->tag.stype = VIO_SUBTYPE_INFO;
			pkt->tag.stype_env = VIO_DRING_DATA;
			pkt->seq = dr->rcv_nxt;
			pkt->start_idx = vio_dring_next(dr,
							port->napi_stop_idx);
			pkt->end_idx = -1;
		} else {
			err = ldc_read(vio->lp, &msgbuf, sizeof(msgbuf));
			if (unlikely(err < 0)) {
				if (err == -ECONNRESET)
					vio_conn_reset(vio);
				break;
			}
			if (err == 0)
				break;
			viodbg(DATA, "TAG [%02x:%02x:%04x:%08x]\n",
			       msgbuf.tag.type,
			       msgbuf.tag.stype,
			       msgbuf.tag.stype_env,
			       msgbuf.tag.sid);
			err = vio_validate_sid(vio, &msgbuf.tag);
			if (err < 0)
				break;
		}

		if (likely(msgbuf.tag.type == VIO_TYPE_DATA)) {
			if (msgbuf.tag.stype == VIO_SUBTYPE_INFO) {
				if (!sunvnet_port_is_up_common(port)) {
					/* failures like handshake_failure()
					 * may have cleaned up dring, but
					 * NAPI polling may bring us here.
					 */
					err = -ECONNRESET;
					break;
				}
				err = vnet_rx(port, &msgbuf, &npkts, budget);
				if (npkts >= budget)
					break;
				if (npkts == 0)
					break;
			} else if (msgbuf.tag.stype == VIO_SUBTYPE_ACK) {
				err = vnet_ack(port, &msgbuf);
				if (err > 0)
					tx_wakeup |= err;
			} else if (msgbuf.tag.stype == VIO_SUBTYPE_NACK) {
				err = vnet_nack(port, &msgbuf);
			}
		} else if (msgbuf.tag.type == VIO_TYPE_CTRL) {
			if (msgbuf.tag.stype_env == VNET_MCAST_INFO)
				err = handle_mcast(port, &msgbuf);
			else
				err = vio_control_pkt_engine(vio, &msgbuf);
			if (err)
				break;
		} else {
			err = vnet_handle_unknown(port, &msgbuf);
		}
		if (err == -ECONNRESET)
			break;
	}
	if (unlikely(tx_wakeup && err != -ECONNRESET))
		maybe_tx_wakeup(port);
	return npkts;
}

int sunvnet_poll_common(struct napi_struct *napi, int budget)
{
	struct vnet_port *port = container_of(napi, struct vnet_port, napi);
	struct vio_driver_state *vio = &port->vio;
	int processed = vnet_event_napi(port, budget);

	if (processed < budget) {
		napi_complete_done(napi, processed);
		port->rx_event &= ~LDC_EVENT_DATA_READY;
		vio_set_intr(vio->vdev->rx_ino, HV_INTR_ENABLED);
	}
	return processed;
}
EXPORT_SYMBOL_GPL(sunvnet_poll_common);

void sunvnet_event_common(void *arg, int event)
{
	struct vnet_port *port = arg;
	struct vio_driver_state *vio = &port->vio;

	port->rx_event |= event;
	vio_set_intr(vio->vdev->rx_ino, HV_INTR_DISABLED);
	napi_schedule(&port->napi);
}
EXPORT_SYMBOL_GPL(sunvnet_event_common);

static int __vnet_tx_trigger(struct vnet_port *port, u32 start)
{
	struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
	struct vio_dring_data hdr = {
		.tag = {
			.type		= VIO_TYPE_DATA,
			.stype		= VIO_SUBTYPE_INFO,
			.stype_env	= VIO_DRING_DATA,
			.sid		= vio_send_sid(&port->vio),
		},
		.dring_ident		= dr->ident,
		.start_idx		= start,
		.end_idx		= (u32)-1,
	};
	int err, delay;
	int retries = 0;

	if (port->stop_rx) {
		trace_vnet_tx_pending_stopped_ack(port->vio._local_sid,
						  port->vio._peer_sid,
						  port->stop_rx_idx, -1);
		err = vnet_send_ack(port,
				    &port->vio.drings[VIO_DRIVER_RX_RING],
				    port->stop_rx_idx, -1,
				    VIO_DRING_STOPPED);
		if (err <= 0)
			return err;
	}

	hdr.seq = dr->snd_nxt;
	delay = 1;
	do {
		err = vio_ldc_send(&port->vio, &hdr, sizeof(hdr));
		if (err > 0) {
			dr->snd_nxt++;
			break;
		}
		udelay(delay);
		if ((delay <<= 1) > 128)
			delay = 128;
		if (retries++ > VNET_MAX_RETRIES)
			break;
	} while (err == -EAGAIN);
	trace_vnet_tx_trigger(port->vio._local_sid,
			      port->vio._peer_sid, start, err);

	return err;
}

static struct sk_buff *vnet_clean_tx_ring(struct vnet_port *port,
					  unsigned *pending)
{
	struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
	struct sk_buff *skb = NULL;
	int i, txi;

	*pending = 0;

	txi = dr->prod;
	for (i = 0; i < VNET_TX_RING_SIZE; ++i) {
		struct vio_net_desc *d;

		--txi;
		if (txi < 0)
			txi = VNET_TX_RING_SIZE - 1;

		d = vio_dring_entry(dr, txi);

		if (d->hdr.state == VIO_DESC_READY) {
			(*pending)++;
			continue;
		}
		if (port->tx_bufs[txi].skb) {
			if (d->hdr.state != VIO_DESC_DONE)
				pr_notice("invalid ring buffer state %d\n",
					  d->hdr.state);
			BUG_ON(port->tx_bufs[txi].skb->next);

			port->tx_bufs[txi].skb->next = skb;
			skb = port->tx_bufs[txi].skb;
			port->tx_bufs[txi].skb = NULL;

			ldc_unmap(port->vio.lp,
				  port->tx_bufs[txi].cookies,
				  port->tx_bufs[txi].ncookies);
		} else if (d->hdr.state == VIO_DESC_FREE) {
			break;
		}
		d->hdr.state = VIO_DESC_FREE;
	}
	return skb;
}

static inline void vnet_free_skbs(struct sk_buff *skb)
{
	struct sk_buff *next;

	while (skb) {
		next = skb->next;
		skb->next = NULL;
		dev_kfree_skb(skb);
		skb = next;
	}
}

void sunvnet_clean_timer_expire_common(struct timer_list *t)
{
	struct vnet_port *port = from_timer(port, t, clean_timer);
	struct sk_buff *freeskbs;
	unsigned pending;

	netif_tx_lock(VNET_PORT_TO_NET_DEVICE(port));
	freeskbs = vnet_clean_tx_ring(port, &pending);
	netif_tx_unlock(VNET_PORT_TO_NET_DEVICE(port));

	vnet_free_skbs(freeskbs);

	if (pending)
		(void)mod_timer(&port->clean_timer,
				jiffies + VNET_CLEAN_TIMEOUT);
	 else
		del_timer(&port->clean_timer);
}
EXPORT_SYMBOL_GPL(sunvnet_clean_timer_expire_common);

static inline int vnet_skb_map(struct ldc_channel *lp, struct sk_buff *skb,
			       struct ldc_trans_cookie *cookies, int ncookies,
			       unsigned int map_perm)
{
	int i, nc, err, blen;

	/* header */
	blen = skb_headlen(skb);
	if (blen < ETH_ZLEN)
		blen = ETH_ZLEN;
	blen += VNET_PACKET_SKIP;
	blen += 8 - (blen & 7);

	err = ldc_map_single(lp, skb->data - VNET_PACKET_SKIP, blen, cookies,
			     ncookies, map_perm);
	if (err < 0)
		return err;
	nc = err;

	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		skb_frag_t *f = &skb_shinfo(skb)->frags[i];
		u8 *vaddr;

		if (nc < ncookies) {
			vaddr = kmap_local_page(skb_frag_page(f));
			blen = skb_frag_size(f);
			blen += 8 - (blen & 7);
			err = ldc_map_single(lp, vaddr + skb_frag_off(f),
					     blen, cookies + nc, ncookies - nc,
					     map_perm);
			kunmap_local(vaddr);
		} else {
			err = -EMSGSIZE;
		}

		if (err < 0) {
			ldc_unmap(lp, cookies, nc);
			return err;
		}
		nc += err;
	}
	return nc;
}

static inline struct sk_buff *vnet_skb_shape(struct sk_buff *skb, int ncookies)
{
	struct sk_buff *nskb;
	int i, len, pad, docopy;

	len = skb->len;
	pad = 0;
	if (len < ETH_ZLEN) {
		pad += ETH_ZLEN - skb->len;
		len += pad;
	}
	len += VNET_PACKET_SKIP;
	pad += 8 - (len & 7);

	/* make sure we have enough cookies and alignment in every frag */
	docopy = skb_shinfo(skb)->nr_frags >= ncookies;
	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		skb_frag_t *f = &skb_shinfo(skb)->frags[i];

		docopy |= skb_frag_off(f) & 7;
	}
	if (((unsigned long)skb->data & 7) != VNET_PACKET_SKIP ||
	    skb_tailroom(skb) < pad ||
	    skb_headroom(skb) < VNET_PACKET_SKIP || docopy) {
		int start = 0, offset;
		__wsum csum;

		len = skb->len > ETH_ZLEN ? skb->len : ETH_ZLEN;
		nskb = alloc_and_align_skb(skb->dev, len);
		if (!nskb) {
			dev_kfree_skb(skb);
			return NULL;
		}
		skb_reserve(nskb, VNET_PACKET_SKIP);

		nskb->protocol = skb->protocol;
		offset = skb_mac_header(skb) - skb->data;
		skb_set_mac_header(nskb, offset);
		offset = skb_network_header(skb) - skb->data;
		skb_set_network_header(nskb, offset);
		offset = skb_transport_header(skb) - skb->data;
		skb_set_transport_header(nskb, offset);

		offset = 0;
		nskb->csum_offset = skb->csum_offset;
		nskb->ip_summed = skb->ip_summed;

		if (skb->ip_summed == CHECKSUM_PARTIAL)
			start = skb_checksum_start_offset(skb);
		if (start) {
			int offset = start + nskb->csum_offset;

			/* copy the headers, no csum here */
			if (skb_copy_bits(skb, 0, nskb->data, start)) {
				dev_kfree_skb(nskb);
				dev_kfree_skb(skb);
				return NULL;
			}

			/* copy the rest, with csum calculation */
			*(__sum16 *)(skb->data + offset) = 0;
			csum = skb_copy_and_csum_bits(skb, start,
						      nskb->data + start,
						      skb->len - start);

			/* add in the header checksums */
			if (skb->protocol == htons(ETH_P_IP)) {
				struct iphdr *iph = ip_hdr(nskb);

				if (iph->protocol == IPPROTO_TCP ||
				    iph->protocol == IPPROTO_UDP) {
					csum = csum_tcpudp_magic(iph->saddr,
								 iph->daddr,
								 skb->len - start,
								 iph->protocol,
								 csum);
				}
			} else if (skb->protocol == htons(ETH_P_IPV6)) {
				struct ipv6hdr *ip6h = ipv6_hdr(nskb);

				if (ip6h->nexthdr == IPPROTO_TCP ||
				    ip6h->nexthdr == IPPROTO_UDP) {
					csum = csum_ipv6_magic(&ip6h->saddr,
							       &ip6h->daddr,
							       skb->len - start,
							       ip6h->nexthdr,
							       csum);
				}
			}

			/* save the final result */
			*(__sum16 *)(nskb->data + offset) = csum;

			nskb->ip_summed = CHECKSUM_NONE;
		} else if (skb_copy_bits(skb, 0, nskb->data, skb->len)) {
			dev_kfree_skb(nskb);
			dev_kfree_skb(skb);
			return NULL;
		}
		(void)skb_put(nskb, skb->len);
		if (skb_is_gso(skb)) {
			skb_shinfo(nskb)->gso_size = skb_shinfo(skb)->gso_size;
			skb_shinfo(nskb)->gso_type = skb_shinfo(skb)->gso_type;
		}
		nskb->queue_mapping = skb->queue_mapping;
		dev_kfree_skb(skb);
		skb = nskb;
	}
	return skb;
}

static netdev_tx_t
vnet_handle_offloads(struct vnet_port *port, struct sk_buff *skb,
		     struct vnet_port *(*vnet_tx_port)
		     (struct sk_buff *, struct net_device *))
{
	struct net_device *dev = VNET_PORT_TO_NET_DEVICE(port);
	struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
	struct sk_buff *segs, *curr, *next;
	int maclen, datalen;
	int status;
	int gso_size, gso_type, gso_segs;
	int hlen = skb_transport_header(skb) - skb_mac_header(skb);
	int proto = IPPROTO_IP;

	if (skb->protocol == htons(ETH_P_IP))
		proto = ip_hdr(skb)->protocol;
	else if (skb->protocol == htons(ETH_P_IPV6))
		proto = ipv6_hdr(skb)->nexthdr;

	if (proto == IPPROTO_TCP) {
		hlen += tcp_hdr(skb)->doff * 4;
	} else if (proto == IPPROTO_UDP) {
		hlen += sizeof(struct udphdr);
	} else {
		pr_err("vnet_handle_offloads GSO with unknown transport "
		       "protocol %d tproto %d\n", skb->protocol, proto);
		hlen = 128; /* XXX */
	}
	datalen = port->tsolen - hlen;

	gso_size = skb_shinfo(skb)->gso_size;
	gso_type = skb_shinfo(skb)->gso_type;
	gso_segs = skb_shinfo(skb)->gso_segs;

	if (port->tso && gso_size < datalen)
		gso_segs = DIV_ROUND_UP(skb->len - hlen, datalen);

	if (unlikely(vnet_tx_dring_avail(dr) < gso_segs)) {
		struct netdev_queue *txq;

		txq  = netdev_get_tx_queue(dev, port->q_index);
		netif_tx_stop_queue(txq);
		if (vnet_tx_dring_avail(dr) < skb_shinfo(skb)->gso_segs)
			return NETDEV_TX_BUSY;
		netif_tx_wake_queue(txq);
	}

	maclen = skb_network_header(skb) - skb_mac_header(skb);
	skb_pull(skb, maclen);

	if (port->tso && gso_size < datalen) {
		if (skb_unclone(skb, GFP_ATOMIC))
			goto out_dropped;

		/* segment to TSO size */
		skb_shinfo(skb)->gso_size = datalen;
		skb_shinfo(skb)->gso_segs = gso_segs;
	}
	segs = skb_gso_segment(skb, dev->features & ~NETIF_F_TSO);
	if (IS_ERR(segs))
		goto out_dropped;

	skb_push(skb, maclen);
	skb_reset_mac_header(skb);

	status = 0;
	skb_list_walk_safe(segs, curr, next) {
		skb_mark_not_on_list(curr);
		if (port->tso && curr->len > dev->mtu) {
			skb_shinfo(curr)->gso_size = gso_size;
			skb_shinfo(curr)->gso_type = gso_type;
			skb_shinfo(curr)->gso_segs =
				DIV_ROUND_UP(curr->len - hlen, gso_size);
		} else {
			skb_shinfo(curr)->gso_size = 0;
		}

		skb_push(curr, maclen);
		skb_reset_mac_header(curr);
		memcpy(skb_mac_header(curr), skb_mac_header(skb),
		       maclen);
		curr->csum_start = skb_transport_header(curr) - curr->head;
		if (ip_hdr(curr)->protocol == IPPROTO_TCP)
			curr->csum_offset = offsetof(struct tcphdr, check);
		else if (ip_hdr(curr)->protocol == IPPROTO_UDP)
			curr->csum_offset = offsetof(struct udphdr, check);

		if (!(status & NETDEV_TX_MASK))
			status = sunvnet_start_xmit_common(curr, dev,
							   vnet_tx_port);
		if (status & NETDEV_TX_MASK)
			dev_kfree_skb_any(curr);
	}

	if (!(status & NETDEV_TX_MASK))
		dev_kfree_skb_any(skb);
	return status;
out_dropped:
	dev->stats.tx_dropped++;
	dev_kfree_skb_any(skb);
	return NETDEV_TX_OK;
}

netdev_tx_t
sunvnet_start_xmit_common(struct sk_buff *skb, struct net_device *dev,
			  struct vnet_port *(*vnet_tx_port)
			  (struct sk_buff *, struct net_device *))
{
	struct vnet_port *port = NULL;
	struct vio_dring_state *dr;
	struct vio_net_desc *d;
	unsigned int len;
	struct sk_buff *freeskbs = NULL;
	int i, err, txi;
	unsigned pending = 0;
	struct netdev_queue *txq;

	rcu_read_lock();
	port = vnet_tx_port(skb, dev);
	if (unlikely(!port))
		goto out_dropped;

	if (skb_is_gso(skb) && skb->len > port->tsolen) {
		err = vnet_handle_offloads(port, skb, vnet_tx_port);
		rcu_read_unlock();
		return err;
	}

	if (!skb_is_gso(skb) && skb->len > port->rmtu) {
		unsigned long localmtu = port->rmtu - ETH_HLEN;

		if (vio_version_after_eq(&port->vio, 1, 3))
			localmtu -= VLAN_HLEN;

		if (skb->protocol == htons(ETH_P_IP))
			icmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
				      htonl(localmtu));
#if IS_ENABLED(CONFIG_IPV6)
		else if (skb->protocol == htons(ETH_P_IPV6))
			icmpv6_ndo_send(skb, ICMPV6_PKT_TOOBIG, 0, localmtu);
#endif
		goto out_dropped;
	}

	skb = vnet_skb_shape(skb, 2);

	if (unlikely(!skb))
		goto out_dropped;

	if (skb->ip_summed == CHECKSUM_PARTIAL) {
		if (skb->protocol == htons(ETH_P_IP))
			vnet_fullcsum_ipv4(skb);
#if IS_ENABLED(CONFIG_IPV6)
		else if (skb->protocol == htons(ETH_P_IPV6))
			vnet_fullcsum_ipv6(skb);
#endif
	}

	dr = &port->vio.drings[VIO_DRIVER_TX_RING];
	i = skb_get_queue_mapping(skb);
	txq = netdev_get_tx_queue(dev, i);
	if (unlikely(vnet_tx_dring_avail(dr) < 1)) {
		if (!netif_tx_queue_stopped(txq)) {
			netif_tx_stop_queue(txq);

			/* This is a hard error, log it. */
			netdev_err(dev, "BUG! Tx Ring full when queue awake!\n");
			dev->stats.tx_errors++;
		}
		rcu_read_unlock();
		return NETDEV_TX_BUSY;
	}

	d = vio_dring_cur(dr);

	txi = dr->prod;

	freeskbs = vnet_clean_tx_ring(port, &pending);

	BUG_ON(port->tx_bufs[txi].skb);

	len = skb->len;
	if (len < ETH_ZLEN)
		len = ETH_ZLEN;

	err = vnet_skb_map(port->vio.lp, skb, port->tx_bufs[txi].cookies, 2,
			   (LDC_MAP_SHADOW | LDC_MAP_DIRECT | LDC_MAP_RW));
	if (err < 0) {
		netdev_info(dev, "tx buffer map error %d\n", err);
		goto out_dropped;
	}

	port->tx_bufs[txi].skb = skb;
	skb = NULL;
	port->tx_bufs[txi].ncookies = err;

	/* We don't rely on the ACKs to free the skb in vnet_start_xmit(),
	 * thus it is safe to not set VIO_ACK_ENABLE for each transmission:
	 * the protocol itself does not require it as long as the peer
	 * sends a VIO_SUBTYPE_ACK for VIO_DRING_STOPPED.
	 *
	 * An ACK for every packet in the ring is expensive as the
	 * sending of LDC messages is slow and affects performance.
	 */
	d->hdr.ack = VIO_ACK_DISABLE;
	d->size = len;
	d->ncookies = port->tx_bufs[txi].ncookies;
	for (i = 0; i < d->ncookies; i++)
		d->cookies[i] = port->tx_bufs[txi].cookies[i];
	if (vio_version_after_eq(&port->vio, 1, 7)) {
		struct vio_net_dext *dext = vio_net_ext(d);

		memset(dext, 0, sizeof(*dext));
		if (skb_is_gso(port->tx_bufs[txi].skb)) {
			dext->ipv4_lso_mss = skb_shinfo(port->tx_bufs[txi].skb)
					     ->gso_size;
			dext->flags |= VNET_PKT_IPV4_LSO;
		}
		if (vio_version_after_eq(&port->vio, 1, 8) &&
		    !port->switch_port) {
			dext->flags |= VNET_PKT_HCK_IPV4_HDRCKSUM_OK;
			dext->flags |= VNET_PKT_HCK_FULLCKSUM_OK;
		}
	}

	/* This has to be a non-SMP write barrier because we are writing
	 * to memory which is shared with the peer LDOM.
	 */
	dma_wmb();

	d->hdr.state = VIO_DESC_READY;

	/* Exactly one ldc "start" trigger (for dr->cons) needs to be sent
	 * to notify the consumer that some descriptors are READY.
	 * After that "start" trigger, no additional triggers are needed until
	 * a DRING_STOPPED is received from the consumer. The dr->cons field
	 * (set up by vnet_ack()) has the value of the next dring index
	 * that has not yet been ack-ed. We send a "start" trigger here
	 * if, and only if, start_cons is true (reset it afterward). Conversely,
	 * vnet_ack() should check if the dring corresponding to cons
	 * is marked READY, but start_cons was false.
	 * If so, vnet_ack() should send out the missed "start" trigger.
	 *
	 * Note that the dma_wmb() above makes sure the cookies et al. are
	 * not globally visible before the VIO_DESC_READY, and that the
	 * stores are ordered correctly by the compiler. The consumer will
	 * not proceed until the VIO_DESC_READY is visible assuring that
	 * the consumer does not observe anything related to descriptors
	 * out of order. The HV trap from the LDC start trigger is the
	 * producer to consumer announcement that work is available to the
	 * consumer
	 */
	if (!port->start_cons) { /* previous trigger suffices */
		trace_vnet_skip_tx_trigger(port->vio._local_sid,
					   port->vio._peer_sid, dr->cons);
		goto ldc_start_done;
	}

	err = __vnet_tx_trigger(port, dr->cons);
	if (unlikely(err < 0)) {
		netdev_info(dev, "TX trigger error %d\n", err);
		d->hdr.state = VIO_DESC_FREE;
		skb = port->tx_bufs[txi].skb;
		port->tx_bufs[txi].skb = NULL;
		dev->stats.tx_carrier_errors++;
		goto out_dropped;
	}

ldc_start_done:
	port->start_cons = false;

	dev->stats.tx_packets++;
	dev->stats.tx_bytes += port->tx_bufs[txi].skb->len;
	port->stats.tx_packets++;
	port->stats.tx_bytes += port->tx_bufs[txi].skb->len;

	dr->prod = (dr->prod + 1) & (VNET_TX_RING_SIZE - 1);
	if (unlikely(vnet_tx_dring_avail(dr) < 1)) {
		netif_tx_stop_queue(txq);
		smp_rmb();
		if (vnet_tx_dring_avail(dr) > VNET_TX_WAKEUP_THRESH(dr))
			netif_tx_wake_queue(txq);
	}

	(void)mod_timer(&port->clean_timer, jiffies + VNET_CLEAN_TIMEOUT);
	rcu_read_unlock();

	vnet_free_skbs(freeskbs);

	return NETDEV_TX_OK;

out_dropped:
	if (pending)
		(void)mod_timer(&port->clean_timer,
				jiffies + VNET_CLEAN_TIMEOUT);
	else if (port)
		del_timer(&port->clean_timer);
	rcu_read_unlock();
	dev_kfree_skb(skb);
	vnet_free_skbs(freeskbs);
	dev->stats.tx_dropped++;
	return NETDEV_TX_OK;
}
EXPORT_SYMBOL_GPL(sunvnet_start_xmit_common);

void sunvnet_tx_timeout_common(struct net_device *dev, unsigned int txqueue)
{
	/* XXX Implement me XXX */
}
EXPORT_SYMBOL_GPL(sunvnet_tx_timeout_common);

int sunvnet_open_common(struct net_device *dev)
{
	netif_carrier_on(dev);
	netif_tx_start_all_queues(dev);

	return 0;
}
EXPORT_SYMBOL_GPL(sunvnet_open_common);

int sunvnet_close_common(struct net_device *dev)
{
	netif_tx_stop_all_queues(dev);
	netif_carrier_off(dev);

	return 0;
}
EXPORT_SYMBOL_GPL(sunvnet_close_common);

static struct vnet_mcast_entry *__vnet_mc_find(struct vnet *vp, u8 *addr)
{
	struct vnet_mcast_entry *m;

	for (m = vp->mcast_list; m; m = m->next) {
		if (ether_addr_equal(m->addr, addr))
			return m;
	}
	return NULL;
}

static void __update_mc_list(struct vnet *vp, struct net_device *dev)
{
	struct netdev_hw_addr *ha;

	netdev_for_each_mc_addr(ha, dev) {
		struct vnet_mcast_entry *m;

		m = __vnet_mc_find(vp, ha->addr);
		if (m) {
			m->hit = 1;
			continue;
		}

		if (!m) {
			m = kzalloc(sizeof(*m), GFP_ATOMIC);
			if (!m)
				continue;
			memcpy(m->addr, ha->addr, ETH_ALEN);
			m->hit = 1;

			m->next = vp->mcast_list;
			vp->mcast_list = m;
		}
	}
}

static void __send_mc_list(struct vnet *vp, struct vnet_port *port)
{
	struct vio_net_mcast_info info;
	struct vnet_mcast_entry *m, **pp;
	int n_addrs;

	memset(&info, 0, sizeof(info));

	info.tag.type = VIO_TYPE_CTRL;
	info.tag.stype = VIO_SUBTYPE_INFO;
	info.tag.stype_env = VNET_MCAST_INFO;
	info.tag.sid = vio_send_sid(&port->vio);
	info.set = 1;

	n_addrs = 0;
	for (m = vp->mcast_list; m; m = m->next) {
		if (m->sent)
			continue;
		m->sent = 1;
		memcpy(&info.mcast_addr[n_addrs * ETH_ALEN],
		       m->addr, ETH_ALEN);
		if (++n_addrs == VNET_NUM_MCAST) {
			info.count = n_addrs;

			(void)vio_ldc_send(&port->vio, &info,
					   sizeof(info));
			n_addrs = 0;
		}
	}
	if (n_addrs) {
		info.count = n_addrs;
		(void)vio_ldc_send(&port->vio, &info, sizeof(info));
	}

	info.set = 0;

	n_addrs = 0;
	pp = &vp->mcast_list;
	while ((m = *pp) != NULL) {
		if (m->hit) {
			m->hit = 0;
			pp = &m->next;
			continue;
		}

		memcpy(&info.mcast_addr[n_addrs * ETH_ALEN],
		       m->addr, ETH_ALEN);
		if (++n_addrs == VNET_NUM_MCAST) {
			info.count = n_addrs;
			(void)vio_ldc_send(&port->vio, &info,
					   sizeof(info));
			n_addrs = 0;
		}

		*pp = m->next;
		kfree(m);
	}
	if (n_addrs) {
		info.count = n_addrs;
		(void)vio_ldc_send(&port->vio, &info, sizeof(info));
	}
}

void sunvnet_set_rx_mode_common(struct net_device *dev, struct vnet *vp)
{
	struct vnet_port *port;

	rcu_read_lock();
	list_for_each_entry_rcu(port, &vp->port_list, list) {
		if (port->switch_port) {
			__update_mc_list(vp, dev);
			__send_mc_list(vp, port);
			break;
		}
	}
	rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(sunvnet_set_rx_mode_common);

int sunvnet_set_mac_addr_common(struct net_device *dev, void *p)
{
	return -EINVAL;
}
EXPORT_SYMBOL_GPL(sunvnet_set_mac_addr_common);

void sunvnet_port_free_tx_bufs_common(struct vnet_port *port)
{
	struct vio_dring_state *dr;
	int i;

	dr = &port->vio.drings[VIO_DRIVER_TX_RING];

	if (!dr->base)
		return;

	for (i = 0; i < VNET_TX_RING_SIZE; i++) {
		struct vio_net_desc *d;
		void *skb = port->tx_bufs[i].skb;

		if (!skb)
			continue;

		d = vio_dring_entry(dr, i);

		ldc_unmap(port->vio.lp,
			  port->tx_bufs[i].cookies,
			  port->tx_bufs[i].ncookies);
		dev_kfree_skb(skb);
		port->tx_bufs[i].skb = NULL;
		d->hdr.state = VIO_DESC_FREE;
	}
	ldc_free_exp_dring(port->vio.lp, dr->base,
			   (dr->entry_size * dr->num_entries),
			   dr->cookies, dr->ncookies);
	dr->base = NULL;
	dr->entry_size = 0;
	dr->num_entries = 0;
	dr->pending = 0;
	dr->ncookies = 0;
}
EXPORT_SYMBOL_GPL(sunvnet_port_free_tx_bufs_common);

void vnet_port_reset(struct vnet_port *port)
{
	del_timer(&port->clean_timer);
	sunvnet_port_free_tx_bufs_common(port);
	port->rmtu = 0;
	port->tso = (port->vsw == 0);  /* no tso in vsw, misbehaves in bridge */
	port->tsolen = 0;
}
EXPORT_SYMBOL_GPL(vnet_port_reset);

static int vnet_port_alloc_tx_ring(struct vnet_port *port)
{
	struct vio_dring_state *dr;
	unsigned long len, elen;
	int i, err, ncookies;
	void *dring;

	dr = &port->vio.drings[VIO_DRIVER_TX_RING];

	elen = sizeof(struct vio_net_desc) +
	       sizeof(struct ldc_trans_cookie) * 2;
	if (vio_version_after_eq(&port->vio, 1, 7))
		elen += sizeof(struct vio_net_dext);
	len = VNET_TX_RING_SIZE * elen;

	ncookies = VIO_MAX_RING_COOKIES;
	dring = ldc_alloc_exp_dring(port->vio.lp, len,
				    dr->cookies, &ncookies,
				    (LDC_MAP_SHADOW |
				     LDC_MAP_DIRECT |
				     LDC_MAP_RW));
	if (IS_ERR(dring)) {
		err = PTR_ERR(dring);
		goto err_out;
	}

	dr->base = dring;
	dr->entry_size = elen;
	dr->num_entries = VNET_TX_RING_SIZE;
	dr->prod = 0;
	dr->cons = 0;
	port->start_cons  = true; /* need an initial trigger */
	dr->pending = VNET_TX_RING_SIZE;
	dr->ncookies = ncookies;

	for (i = 0; i < VNET_TX_RING_SIZE; ++i) {
		struct vio_net_desc *d;

		d = vio_dring_entry(dr, i);
		d->hdr.state = VIO_DESC_FREE;
	}
	return 0;

err_out:
	sunvnet_port_free_tx_bufs_common(port);

	return err;
}

#ifdef CONFIG_NET_POLL_CONTROLLER
void sunvnet_poll_controller_common(struct net_device *dev, struct vnet *vp)
{
	struct vnet_port *port;
	unsigned long flags;

	spin_lock_irqsave(&vp->lock, flags);
	if (!list_empty(&vp->port_list)) {
		port = list_entry(vp->port_list.next, struct vnet_port, list);
		napi_schedule(&port->napi);
	}
	spin_unlock_irqrestore(&vp->lock, flags);
}
EXPORT_SYMBOL_GPL(sunvnet_poll_controller_common);
#endif

void sunvnet_port_add_txq_common(struct vnet_port *port)
{
	struct vnet *vp = port->vp;
	int smallest = 0;
	int i;

	/* find the first least-used q
	 * When there are more ldoms than q's, we start to
	 * double up on ports per queue.
	 */
	for (i = 0; i < VNET_MAX_TXQS; i++) {
		if (vp->q_used[i] == 0) {
			smallest = i;
			break;
		}
		if (vp->q_used[i] < vp->q_used[smallest])
			smallest = i;
	}

	vp->nports++;
	vp->q_used[smallest]++;
	port->q_index = smallest;
}
EXPORT_SYMBOL_GPL(sunvnet_port_add_txq_common);

void sunvnet_port_rm_txq_common(struct vnet_port *port)
{
	port->vp->nports--;
	port->vp->q_used[port->q_index]--;
	port->q_index = 0;
}
EXPORT_SYMBOL_GPL(sunvnet_port_rm_txq_common);