1 files changed, 2277 insertions, 0 deletions

diff --git a/sys/dev/netmap/if_ptnet.c b/sys/dev/netmap/if_ptnet.c
new file mode 100644
index 000000000000..86b500e36e18
--- /dev/null
+++ b/sys/dev/netmap/if_ptnet.c
@@ -0,0 +1,2277 @@
+/*-
+ * Copyright (c) 2016, Vincenzo Maffione
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice unmodified, this list of conditions, and the following
+ *    disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+/* Driver for ptnet paravirtualized network device. */
+
+#include <sys/cdefs.h>
+
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/sockio.h>
+#include <sys/mbuf.h>
+#include <sys/malloc.h>
+#include <sys/module.h>
+#include <sys/socket.h>
+#include <sys/sysctl.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
+#include <sys/taskqueue.h>
+#include <sys/smp.h>
+#include <sys/time.h>
+#include <machine/smp.h>
+
+#include <vm/uma.h>
+#include <vm/vm.h>
+#include <vm/pmap.h>
+
+#include <net/ethernet.h>
+#include <net/if.h>
+#include <net/if_var.h>
+#include <net/if_arp.h>
+#include <net/if_dl.h>
+#include <net/if_types.h>
+#include <net/if_media.h>
+#include <net/if_vlan_var.h>
+#include <net/bpf.h>
+
+#include <netinet/in_systm.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/ip6.h>
+#include <netinet6/ip6_var.h>
+#include <netinet/udp.h>
+#include <netinet/tcp.h>
+#include <netinet/sctp.h>
+
+#include <machine/bus.h>
+#include <machine/resource.h>
+#include <sys/bus.h>
+#include <sys/rman.h>
+
+#include <dev/pci/pcivar.h>
+#include <dev/pci/pcireg.h>
+
+#include "opt_inet.h"
+#include "opt_inet6.h"
+
+#include <sys/selinfo.h>
+#include <net/netmap.h>
+#include <dev/netmap/netmap_kern.h>
+#include <net/netmap_virt.h>
+#include <dev/netmap/netmap_mem2.h>
+#include <dev/virtio/network/virtio_net.h>
+
+#ifndef PTNET_CSB_ALLOC
+#error "No support for on-device CSB"
+#endif
+
+#ifndef INET
+#error "INET not defined, cannot support offloadings"
+#endif
+
+#if __FreeBSD_version >= 1100000
+static uint64_t	ptnet_get_counter(if_t, ift_counter);
+#else
+typedef struct ifnet *if_t;
+#define if_getsoftc(_ifp)   (_ifp)->if_softc
+#endif
+
+//#define PTNETMAP_STATS
+//#define DEBUG
+#ifdef DEBUG
+#define DBG(x) x
+#else   /* !DEBUG */
+#define DBG(x)
+#endif  /* !DEBUG */
+
+extern int ptnet_vnet_hdr; /* Tunable parameter */
+
+struct ptnet_softc;
+
+struct ptnet_queue_stats {
+	uint64_t	packets; /* if_[io]packets */
+	uint64_t	bytes;	 /* if_[io]bytes */
+	uint64_t	errors;	 /* if_[io]errors */
+	uint64_t	iqdrops; /* if_iqdrops */
+	uint64_t	mcasts;  /* if_[io]mcasts */
+#ifdef PTNETMAP_STATS
+	uint64_t	intrs;
+	uint64_t	kicks;
+#endif /* PTNETMAP_STATS */
+};
+
+struct ptnet_queue {
+	struct ptnet_softc		*sc;
+	struct				resource *irq;
+	void				*cookie;
+	int				kring_id;
+	struct ptnet_ring		*ptring;
+	unsigned int			kick;
+	struct mtx			lock;
+	struct buf_ring			*bufring; /* for TX queues */
+	struct ptnet_queue_stats	stats;
+#ifdef PTNETMAP_STATS
+	struct ptnet_queue_stats	last_stats;
+#endif /* PTNETMAP_STATS */
+	struct taskqueue		*taskq;
+	struct task			task;
+	char				lock_name[16];
+};
+
+#define PTNET_Q_LOCK(_pq)	mtx_lock(&(_pq)->lock)
+#define PTNET_Q_TRYLOCK(_pq)	mtx_trylock(&(_pq)->lock)
+#define PTNET_Q_UNLOCK(_pq)	mtx_unlock(&(_pq)->lock)
+
+struct ptnet_softc {
+	device_t		dev;
+	if_t			ifp;
+	struct ifmedia		media;
+	struct mtx		lock;
+	char			lock_name[16];
+	char			hwaddr[ETHER_ADDR_LEN];
+
+	/* Mirror of PTFEAT register. */
+	uint32_t		ptfeatures;
+	unsigned int		vnet_hdr_len;
+
+	/* PCI BARs support. */
+	struct resource		*iomem;
+	struct resource		*msix_mem;
+
+	unsigned int		num_rings;
+	unsigned int		num_tx_rings;
+	struct ptnet_queue	*queues;
+	struct ptnet_queue	*rxqueues;
+	struct ptnet_csb	*csb;
+
+	unsigned int		min_tx_space;
+
+	struct netmap_pt_guest_adapter *ptna;
+
+	struct callout		tick;
+#ifdef PTNETMAP_STATS
+	struct timeval		last_ts;
+#endif /* PTNETMAP_STATS */
+};
+
+#define PTNET_CORE_LOCK(_sc)	mtx_lock(&(_sc)->lock)
+#define PTNET_CORE_UNLOCK(_sc)	mtx_unlock(&(_sc)->lock)
+
+static int	ptnet_probe(device_t);
+static int	ptnet_attach(device_t);
+static int	ptnet_detach(device_t);
+static int	ptnet_suspend(device_t);
+static int	ptnet_resume(device_t);
+static int	ptnet_shutdown(device_t);
+
+static void	ptnet_init(void *opaque);
+static int	ptnet_ioctl(if_t ifp, u_long cmd, caddr_t data);
+static int	ptnet_init_locked(struct ptnet_softc *sc);
+static int	ptnet_stop(struct ptnet_softc *sc);
+static int	ptnet_transmit(if_t ifp, struct mbuf *m);
+static int	ptnet_drain_transmit_queue(struct ptnet_queue *pq,
+					   unsigned int budget,
+					   bool may_resched);
+static void	ptnet_qflush(if_t ifp);
+static void	ptnet_tx_task(void *context, int pending);
+
+static int	ptnet_media_change(if_t ifp);
+static void	ptnet_media_status(if_t ifp, struct ifmediareq *ifmr);
+#ifdef PTNETMAP_STATS
+static void	ptnet_tick(void *opaque);
+#endif
+
+static int	ptnet_irqs_init(struct ptnet_softc *sc);
+static void	ptnet_irqs_fini(struct ptnet_softc *sc);
+
+static uint32_t ptnet_nm_ptctl(if_t ifp, uint32_t cmd);
+static int	ptnet_nm_config(struct netmap_adapter *na, unsigned *txr,
+				unsigned *txd, unsigned *rxr, unsigned *rxd);
+static void	ptnet_update_vnet_hdr(struct ptnet_softc *sc);
+static int	ptnet_nm_register(struct netmap_adapter *na, int onoff);
+static int	ptnet_nm_txsync(struct netmap_kring *kring, int flags);
+static int	ptnet_nm_rxsync(struct netmap_kring *kring, int flags);
+
+static void	ptnet_tx_intr(void *opaque);
+static void	ptnet_rx_intr(void *opaque);
+
+static unsigned	ptnet_rx_discard(struct netmap_kring *kring,
+				 unsigned int head);
+static int	ptnet_rx_eof(struct ptnet_queue *pq, unsigned int budget,
+			     bool may_resched);
+static void	ptnet_rx_task(void *context, int pending);
+
+#ifdef DEVICE_POLLING
+static poll_handler_t ptnet_poll;
+#endif
+
+static device_method_t ptnet_methods[] = {
+	DEVMETHOD(device_probe,			ptnet_probe),
+	DEVMETHOD(device_attach,		ptnet_attach),
+	DEVMETHOD(device_detach,		ptnet_detach),
+	DEVMETHOD(device_suspend,		ptnet_suspend),
+	DEVMETHOD(device_resume,		ptnet_resume),
+	DEVMETHOD(device_shutdown,		ptnet_shutdown),
+	DEVMETHOD_END
+};
+
+static driver_t ptnet_driver = {
+	"ptnet",
+	ptnet_methods,
+	sizeof(struct ptnet_softc)
+};
+
+/* We use (SI_ORDER_MIDDLE+2) here, see DEV_MODULE_ORDERED() invocation. */
+static devclass_t ptnet_devclass;
+DRIVER_MODULE_ORDERED(ptnet, pci, ptnet_driver, ptnet_devclass,
+		      NULL, NULL, SI_ORDER_MIDDLE + 2);
+
+static int
+ptnet_probe(device_t dev)
+{
+	if (pci_get_vendor(dev) != PTNETMAP_PCI_VENDOR_ID ||
+		pci_get_device(dev) != PTNETMAP_PCI_NETIF_ID) {
+		return (ENXIO);
+	}
+
+	device_set_desc(dev, "ptnet network adapter");
+
+	return (BUS_PROBE_DEFAULT);
+}
+
+static inline void ptnet_kick(struct ptnet_queue *pq)
+{
+#ifdef PTNETMAP_STATS
+	pq->stats.kicks ++;
+#endif /* PTNETMAP_STATS */
+	bus_write_4(pq->sc->iomem, pq->kick, 0);
+}
+
+#define PTNET_BUF_RING_SIZE	4096
+#define PTNET_RX_BUDGET		512
+#define PTNET_RX_BATCH		1
+#define PTNET_TX_BUDGET		512
+#define PTNET_TX_BATCH		64
+#define PTNET_HDR_SIZE		sizeof(struct virtio_net_hdr_mrg_rxbuf)
+#define PTNET_MAX_PKT_SIZE	65536
+
+#define PTNET_CSUM_OFFLOAD	(CSUM_TCP | CSUM_UDP | CSUM_SCTP)
+#define PTNET_CSUM_OFFLOAD_IPV6	(CSUM_TCP_IPV6 | CSUM_UDP_IPV6 |\
+				 CSUM_SCTP_IPV6)
+#define PTNET_ALL_OFFLOAD	(CSUM_TSO | PTNET_CSUM_OFFLOAD |\
+				 PTNET_CSUM_OFFLOAD_IPV6)
+
+static int
+ptnet_attach(device_t dev)
+{
+	uint32_t ptfeatures = PTNETMAP_F_BASE;
+	unsigned int num_rx_rings, num_tx_rings;
+	struct netmap_adapter na_arg;
+	unsigned int nifp_offset;
+	struct ptnet_softc *sc;
+	if_t ifp;
+	uint32_t macreg;
+	int err, rid;
+	int i;
+
+	sc = device_get_softc(dev);
+	sc->dev = dev;
+
+	/* Setup PCI resources. */
+	pci_enable_busmaster(dev);
+
+	rid = PCIR_BAR(PTNETMAP_IO_PCI_BAR);
+	sc->iomem = bus_alloc_resource_any(dev, SYS_RES_IOPORT, &rid,
+					   RF_ACTIVE);
+	if (sc->iomem == NULL) {
+		device_printf(dev, "Failed to map I/O BAR\n");
+		return (ENXIO);
+	}
+
+	/* Check if we are supported by the hypervisor. If not,
+	 * bail out immediately. */
+	if (ptnet_vnet_hdr) {
+		ptfeatures |= PTNETMAP_F_VNET_HDR;
+	}
+	bus_write_4(sc->iomem, PTNET_IO_PTFEAT, ptfeatures); /* wanted */
+	ptfeatures = bus_read_4(sc->iomem, PTNET_IO_PTFEAT); /* acked */
+	if (!(ptfeatures & PTNETMAP_F_BASE)) {
+		device_printf(dev, "Hypervisor does not support netmap "
+				   "passthorugh\n");
+		err = ENXIO;
+		goto err_path;
+	}
+	sc->ptfeatures = ptfeatures;
+
+	/* Allocate CSB and carry out CSB allocation protocol (CSBBAH first,
+	 * then CSBBAL). */
+	sc->csb = malloc(sizeof(struct ptnet_csb), M_DEVBUF,
+			 M_NOWAIT | M_ZERO);
+	if (sc->csb == NULL) {
+		device_printf(dev, "Failed to allocate CSB\n");
+		err = ENOMEM;
+		goto err_path;
+	}
+
+	{
+		vm_paddr_t paddr = vtophys(sc->csb);
+
+		bus_write_4(sc->iomem, PTNET_IO_CSBBAH,
+			    (paddr >> 32) & 0xffffffff);
+		bus_write_4(sc->iomem, PTNET_IO_CSBBAL, paddr & 0xffffffff);
+	}
+
+	num_tx_rings = bus_read_4(sc->iomem, PTNET_IO_NUM_TX_RINGS);
+	num_rx_rings = bus_read_4(sc->iomem, PTNET_IO_NUM_RX_RINGS);
+	sc->num_rings = num_tx_rings + num_rx_rings;
+	sc->num_tx_rings = num_tx_rings;
+
+	/* Allocate and initialize per-queue data structures. */
+	sc->queues = malloc(sizeof(struct ptnet_queue) * sc->num_rings,
+			    M_DEVBUF, M_NOWAIT | M_ZERO);
+	if (sc->queues == NULL) {
+		err = ENOMEM;
+		goto err_path;
+	}
+	sc->rxqueues = sc->queues + num_tx_rings;
+
+	for (i = 0; i < sc->num_rings; i++) {
+		struct ptnet_queue *pq = sc->queues + i;
+
+		pq->sc = sc;
+		pq->kring_id = i;
+		pq->kick = PTNET_IO_KICK_BASE + 4 * i;
+		pq->ptring = sc->csb->rings + i;
+		snprintf(pq->lock_name, sizeof(pq->lock_name), "%s-%d",
+			 device_get_nameunit(dev), i);
+		mtx_init(&pq->lock, pq->lock_name, NULL, MTX_DEF);
+		if (i >= num_tx_rings) {
+			/* RX queue: fix kring_id. */
+			pq->kring_id -= num_tx_rings;
+		} else {
+			/* TX queue: allocate buf_ring. */
+			pq->bufring = buf_ring_alloc(PTNET_BUF_RING_SIZE,
+						M_DEVBUF, M_NOWAIT, &pq->lock);
+			if (pq->bufring == NULL) {
+				err = ENOMEM;
+				goto err_path;
+			}
+		}
+	}
+
+	sc->min_tx_space = 64; /* Safe initial value. */
+
+	err = ptnet_irqs_init(sc);
+	if (err) {
+		goto err_path;
+	}
+
+	/* Setup Ethernet interface. */
+	sc->ifp = ifp = if_alloc(IFT_ETHER);
+	if (ifp == NULL) {
+		device_printf(dev, "Failed to allocate ifnet\n");
+		err = ENOMEM;
+		goto err_path;
+	}
+
+	if_initname(ifp, device_get_name(dev), device_get_unit(dev));
+	ifp->if_baudrate = IF_Gbps(10);
+	ifp->if_softc = sc;
+	ifp->if_flags = IFF_BROADCAST | IFF_MULTICAST | IFF_SIMPLEX;
+	ifp->if_init = ptnet_init;
+	ifp->if_ioctl = ptnet_ioctl;
+#if __FreeBSD_version >= 1100000
+	ifp->if_get_counter = ptnet_get_counter;
+#endif
+	ifp->if_transmit = ptnet_transmit;
+	ifp->if_qflush = ptnet_qflush;
+
+	ifmedia_init(&sc->media, IFM_IMASK, ptnet_media_change,
+		     ptnet_media_status);
+	ifmedia_add(&sc->media, IFM_ETHER | IFM_10G_T | IFM_FDX, 0, NULL);
+	ifmedia_set(&sc->media, IFM_ETHER | IFM_10G_T | IFM_FDX);
+
+	macreg = bus_read_4(sc->iomem, PTNET_IO_MAC_HI);
+	sc->hwaddr[0] = (macreg >> 8) & 0xff;
+	sc->hwaddr[1] = macreg & 0xff;
+	macreg = bus_read_4(sc->iomem, PTNET_IO_MAC_LO);
+	sc->hwaddr[2] = (macreg >> 24) & 0xff;
+	sc->hwaddr[3] = (macreg >> 16) & 0xff;
+	sc->hwaddr[4] = (macreg >> 8) & 0xff;
+	sc->hwaddr[5] = macreg & 0xff;
+
+	ether_ifattach(ifp, sc->hwaddr);
+
+	ifp->if_hdrlen = sizeof(struct ether_vlan_header);
+	ifp->if_capabilities |= IFCAP_JUMBO_MTU | IFCAP_VLAN_MTU;
+
+	if (sc->ptfeatures & PTNETMAP_F_VNET_HDR) {
+		/* Similarly to what the vtnet driver does, we can emulate
+		 * VLAN offloadings by inserting and removing the 802.1Q
+		 * header during transmit and receive. We are then able
+		 * to do checksum offloading of VLAN frames. */
+		ifp->if_capabilities |= IFCAP_HWCSUM | IFCAP_HWCSUM_IPV6
+					| IFCAP_VLAN_HWCSUM
+					| IFCAP_TSO | IFCAP_LRO
+					| IFCAP_VLAN_HWTSO
+					| IFCAP_VLAN_HWTAGGING;
+	}
+
+	ifp->if_capenable = ifp->if_capabilities;
+#ifdef DEVICE_POLLING
+	/* Don't enable polling by default. */
+	ifp->if_capabilities |= IFCAP_POLLING;
+#endif
+	snprintf(sc->lock_name, sizeof(sc->lock_name),
+		 "%s", device_get_nameunit(dev));
+	mtx_init(&sc->lock, sc->lock_name, "ptnet core lock", MTX_DEF);
+	callout_init_mtx(&sc->tick, &sc->lock, 0);
+
+	/* Prepare a netmap_adapter struct instance to do netmap_attach(). */
+	nifp_offset = bus_read_4(sc->iomem, PTNET_IO_NIFP_OFS);
+	memset(&na_arg, 0, sizeof(na_arg));
+	na_arg.ifp = ifp;
+	na_arg.num_tx_desc = bus_read_4(sc->iomem, PTNET_IO_NUM_TX_SLOTS);
+	na_arg.num_rx_desc = bus_read_4(sc->iomem, PTNET_IO_NUM_RX_SLOTS);
+	na_arg.num_tx_rings = num_tx_rings;
+	na_arg.num_rx_rings = num_rx_rings;
+	na_arg.nm_config = ptnet_nm_config;
+	na_arg.nm_krings_create = ptnet_nm_krings_create;
+	na_arg.nm_krings_delete = ptnet_nm_krings_delete;
+	na_arg.nm_dtor = ptnet_nm_dtor;
+	na_arg.nm_register = ptnet_nm_register;
+	na_arg.nm_txsync = ptnet_nm_txsync;
+	na_arg.nm_rxsync = ptnet_nm_rxsync;
+
+	netmap_pt_guest_attach(&na_arg, sc->csb, nifp_offset, ptnet_nm_ptctl);
+
+	/* Now a netmap adapter for this ifp has been allocated, and it
+	 * can be accessed through NA(ifp). We also have to initialize the CSB
+	 * pointer. */
+	sc->ptna = (struct netmap_pt_guest_adapter *)NA(ifp);
+
+	/* If virtio-net header was negotiated, set the virt_hdr_len field in
+	 * the netmap adapter, to inform users that this netmap adapter requires
+	 * the application to deal with the headers. */
+	ptnet_update_vnet_hdr(sc);
+
+	device_printf(dev, "%s() completed\n", __func__);
+
+	return (0);
+
+err_path:
+	ptnet_detach(dev);
+	return err;
+}
+
+static int
+ptnet_detach(device_t dev)
+{
+	struct ptnet_softc *sc = device_get_softc(dev);
+	int i;
+
+#ifdef DEVICE_POLLING
+	if (sc->ifp->if_capenable & IFCAP_POLLING) {
+		ether_poll_deregister(sc->ifp);
+	}
+#endif
+	callout_drain(&sc->tick);
+
+	if (sc->queues) {
+		/* Drain taskqueues before calling if_detach. */
+		for (i = 0; i < sc->num_rings; i++) {
+			struct ptnet_queue *pq = sc->queues + i;
+
+			if (pq->taskq) {
+				taskqueue_drain(pq->taskq, &pq->task);
+			}
+		}
+	}
+
+	if (sc->ifp) {
+		ether_ifdetach(sc->ifp);
+
+		/* Uninitialize netmap adapters for this device. */
+		netmap_detach(sc->ifp);
+
+		ifmedia_removeall(&sc->media);
+		if_free(sc->ifp);
+		sc->ifp = NULL;
+	}
+
+	ptnet_irqs_fini(sc);
+
+	if (sc->csb) {
+		bus_write_4(sc->iomem, PTNET_IO_CSBBAH, 0);
+		bus_write_4(sc->iomem, PTNET_IO_CSBBAL, 0);
+		free(sc->csb, M_DEVBUF);
+		sc->csb = NULL;
+	}
+
+	if (sc->queues) {
+		for (i = 0; i < sc->num_rings; i++) {
+			struct ptnet_queue *pq = sc->queues + i;
+
+			if (mtx_initialized(&pq->lock)) {
+				mtx_destroy(&pq->lock);
+			}
+			if (pq->bufring != NULL) {
+				buf_ring_free(pq->bufring, M_DEVBUF);
+			}
+		}
+		free(sc->queues, M_DEVBUF);
+		sc->queues = NULL;
+	}
+
+	if (sc->iomem) {
+		bus_release_resource(dev, SYS_RES_IOPORT,
+				     PCIR_BAR(PTNETMAP_IO_PCI_BAR), sc->iomem);
+		sc->iomem = NULL;
+	}
+
+	mtx_destroy(&sc->lock);
+
+	device_printf(dev, "%s() completed\n", __func__);
+
+	return (0);
+}
+
+static int
+ptnet_suspend(device_t dev)
+{
+	struct ptnet_softc *sc;
+
+	sc = device_get_softc(dev);
+	(void)sc;
+
+	return (0);
+}
+
+static int
+ptnet_resume(device_t dev)
+{
+	struct ptnet_softc *sc;
+
+	sc = device_get_softc(dev);
+	(void)sc;
+
+	return (0);
+}
+
+static int
+ptnet_shutdown(device_t dev)
+{
+	/*
+	 * Suspend already does all of what we need to
+	 * do here; we just never expect to be resumed.
+	 */
+	return (ptnet_suspend(dev));
+}
+
+static int
+ptnet_irqs_init(struct ptnet_softc *sc)
+{
+	int rid = PCIR_BAR(PTNETMAP_MSIX_PCI_BAR);
+	int nvecs = sc->num_rings;
+	device_t dev = sc->dev;
+	int err = ENOSPC;
+	int cpu_cur;
+	int i;
+
+	if (pci_find_cap(dev, PCIY_MSIX, NULL) != 0)  {
+		device_printf(dev, "Could not find MSI-X capability\n");
+		return (ENXIO);
+	}
+
+	sc->msix_mem = bus_alloc_resource_any(dev, SYS_RES_MEMORY,
+					      &rid, RF_ACTIVE);
+	if (sc->msix_mem == NULL) {
+		device_printf(dev, "Failed to allocate MSIX PCI BAR\n");
+		return (ENXIO);
+	}
+
+	if (pci_msix_count(dev) < nvecs) {
+		device_printf(dev, "Not enough MSI-X vectors\n");
+		goto err_path;
+	}
+
+	err = pci_alloc_msix(dev, &nvecs);
+	if (err) {
+		device_printf(dev, "Failed to allocate MSI-X vectors\n");
+		goto err_path;
+	}
+
+	for (i = 0; i < nvecs; i++) {
+		struct ptnet_queue *pq = sc->queues + i;
+
+		rid = i + 1;
+		pq->irq = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid,
+						 RF_ACTIVE);
+		if (pq->irq == NULL) {
+			device_printf(dev, "Failed to allocate interrupt "
+					   "for queue #%d\n", i);
+			err = ENOSPC;
+			goto err_path;
+		}
+	}
+
+	cpu_cur = CPU_FIRST();
+	for (i = 0; i < nvecs; i++) {
+		struct ptnet_queue *pq = sc->queues + i;
+		void (*handler)(void *) = ptnet_tx_intr;
+
+		if (i >= sc->num_tx_rings) {
+			handler = ptnet_rx_intr;
+		}
+		err = bus_setup_intr(dev, pq->irq, INTR_TYPE_NET | INTR_MPSAFE,
+				     NULL /* intr_filter */, handler,
+				     pq, &pq->cookie);
+		if (err) {
+			device_printf(dev, "Failed to register intr handler "
+					   "for queue #%d\n", i);
+			goto err_path;
+		}
+
+		bus_describe_intr(dev, pq->irq, pq->cookie, "q%d", i);
+#if 0
+		bus_bind_intr(sc->dev, pq->irq, cpu_cur);
+#endif
+		cpu_cur = CPU_NEXT(cpu_cur);
+	}
+
+	device_printf(dev, "Allocated %d MSI-X vectors\n", nvecs);
+
+	cpu_cur = CPU_FIRST();
+	for (i = 0; i < nvecs; i++) {
+		struct ptnet_queue *pq = sc->queues + i;
+		static void (*handler)(void *context, int pending);
+
+		handler = (i < sc->num_tx_rings) ? ptnet_tx_task : ptnet_rx_task;
+
+		TASK_INIT(&pq->task, 0, handler, pq);
+		pq->taskq = taskqueue_create_fast("ptnet_queue", M_NOWAIT,
+					taskqueue_thread_enqueue, &pq->taskq);
+		taskqueue_start_threads(&pq->taskq, 1, PI_NET, "%s-pq-%d",
+					device_get_nameunit(sc->dev), cpu_cur);
+		cpu_cur = CPU_NEXT(cpu_cur);
+	}
+
+	return 0;
+err_path:
+	ptnet_irqs_fini(sc);
+	return err;
+}
+
+static void
+ptnet_irqs_fini(struct ptnet_softc *sc)
+{
+	device_t dev = sc->dev;
+	int i;
+
+	for (i = 0; i < sc->num_rings; i++) {
+		struct ptnet_queue *pq = sc->queues + i;
+
+		if (pq->taskq) {
+			taskqueue_free(pq->taskq);
+			pq->taskq = NULL;
+		}
+
+		if (pq->cookie) {
+			bus_teardown_intr(dev, pq->irq, pq->cookie);
+			pq->cookie = NULL;
+		}
+
+		if (pq->irq) {
+			bus_release_resource(dev, SYS_RES_IRQ, i + 1, pq->irq);
+			pq->irq = NULL;
+		}
+	}
+
+	if (sc->msix_mem) {
+		pci_release_msi(dev);
+
+		bus_release_resource(dev, SYS_RES_MEMORY,
+				     PCIR_BAR(PTNETMAP_MSIX_PCI_BAR),
+				     sc->msix_mem);
+		sc->msix_mem = NULL;
+	}
+}
+
+static void
+ptnet_init(void *opaque)
+{
+	struct ptnet_softc *sc = opaque;
+
+	PTNET_CORE_LOCK(sc);
+	ptnet_init_locked(sc);
+	PTNET_CORE_UNLOCK(sc);
+}
+
+static int
+ptnet_ioctl(if_t ifp, u_long cmd, caddr_t data)
+{
+	struct ptnet_softc *sc = if_getsoftc(ifp);
+	device_t dev = sc->dev;
+	struct ifreq *ifr = (struct ifreq *)data;
+	int mask, err = 0;
+
+	switch (cmd) {
+	case SIOCSIFFLAGS:
+		device_printf(dev, "SIOCSIFFLAGS %x\n", ifp->if_flags);
+		PTNET_CORE_LOCK(sc);
+		if (ifp->if_flags & IFF_UP) {
+			/* Network stack wants the iff to be up. */
+			err = ptnet_init_locked(sc);
+		} else {
+			/* Network stack wants the iff to be down. */
+			err = ptnet_stop(sc);
+		}
+		/* We don't need to do nothing to support IFF_PROMISC,
+		 * since that is managed by the backend port. */
+		PTNET_CORE_UNLOCK(sc);
+		break;
+
+	case SIOCSIFCAP:
+		device_printf(dev, "SIOCSIFCAP %x %x\n",
+			      ifr->ifr_reqcap, ifp->if_capenable);
+		mask = ifr->ifr_reqcap ^ ifp->if_capenable;
+#ifdef DEVICE_POLLING
+		if (mask & IFCAP_POLLING) {
+			struct ptnet_queue *pq;
+			int i;
+
+			if (ifr->ifr_reqcap & IFCAP_POLLING) {
+				err = ether_poll_register(ptnet_poll, ifp);
+				if (err) {
+					break;
+				}
+				/* Stop queues and sync with taskqueues. */
+				ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
+				for (i = 0; i < sc->num_rings; i++) {
+					pq = sc-> queues + i;
+					/* Make sure the worker sees the
+					 * IFF_DRV_RUNNING down. */
+					PTNET_Q_LOCK(pq);
+					pq->ptring->guest_need_kick = 0;
+					PTNET_Q_UNLOCK(pq);
+					/* Wait for rescheduling to finish. */
+					if (pq->taskq) {
+						taskqueue_drain(pq->taskq,
+								&pq->task);
+					}
+				}
+				ifp->if_drv_flags |= IFF_DRV_RUNNING;
+			} else {
+				err = ether_poll_deregister(ifp);
+				for (i = 0; i < sc->num_rings; i++) {
+					pq = sc-> queues + i;
+					PTNET_Q_LOCK(pq);
+					pq->ptring->guest_need_kick = 1;
+					PTNET_Q_UNLOCK(pq);
+				}
+			}
+		}
+#endif  /* DEVICE_POLLING */
+		ifp->if_capenable = ifr->ifr_reqcap;
+		break;
+
+	case SIOCSIFMTU:
+		/* We support any reasonable MTU. */
+		if (ifr->ifr_mtu < ETHERMIN ||
+				ifr->ifr_mtu > PTNET_MAX_PKT_SIZE) {
+			err = EINVAL;
+		} else {
+			PTNET_CORE_LOCK(sc);
+			ifp->if_mtu = ifr->ifr_mtu;
+			PTNET_CORE_UNLOCK(sc);
+		}
+		break;
+
+	case SIOCSIFMEDIA:
+	case SIOCGIFMEDIA:
+		err = ifmedia_ioctl(ifp, ifr, &sc->media, cmd);
+		break;
+
+	default:
+		err = ether_ioctl(ifp, cmd, data);
+		break;
+	}
+
+	return err;
+}
+
+static int
+ptnet_init_locked(struct ptnet_softc *sc)
+{
+	if_t ifp = sc->ifp;
+	struct netmap_adapter *na_dr = &sc->ptna->dr.up;
+	struct netmap_adapter *na_nm = &sc->ptna->hwup.up;
+	unsigned int nm_buf_size;
+	int ret;
+
+	if (ifp->if_drv_flags & IFF_DRV_RUNNING) {
+		return 0; /* nothing to do */
+	}
+
+	device_printf(sc->dev, "%s\n", __func__);
+
+	/* Translate offload capabilities according to if_capenable. */
+	ifp->if_hwassist = 0;
+	if (ifp->if_capenable & IFCAP_TXCSUM)
+		ifp->if_hwassist |= PTNET_CSUM_OFFLOAD;
+	if (ifp->if_capenable & IFCAP_TXCSUM_IPV6)
+		ifp->if_hwassist |= PTNET_CSUM_OFFLOAD_IPV6;
+	if (ifp->if_capenable & IFCAP_TSO4)
+		ifp->if_hwassist |= CSUM_IP_TSO;
+	if (ifp->if_capenable & IFCAP_TSO6)
+		ifp->if_hwassist |= CSUM_IP6_TSO;
+
+	/*
+	 * Prepare the interface for netmap mode access.
+	 */
+	netmap_update_config(na_dr);
+
+	ret = netmap_mem_finalize(na_dr->nm_mem, na_dr);
+	if (ret) {
+		device_printf(sc->dev, "netmap_mem_finalize() failed\n");
+		return ret;
+	}
+
+	if (sc->ptna->backend_regifs == 0) {
+		ret = ptnet_nm_krings_create(na_nm);
+		if (ret) {
+			device_printf(sc->dev, "ptnet_nm_krings_create() "
+					       "failed\n");
+			goto err_mem_finalize;
+		}
+
+		ret = netmap_mem_rings_create(na_dr);
+		if (ret) {
+			device_printf(sc->dev, "netmap_mem_rings_create() "
+					       "failed\n");
+			goto err_rings_create;
+		}
+
+		ret = netmap_mem_get_lut(na_dr->nm_mem, &na_dr->na_lut);
+		if (ret) {
+			device_printf(sc->dev, "netmap_mem_get_lut() "
+					       "failed\n");
+			goto err_get_lut;
+		}
+	}
+
+	ret = ptnet_nm_register(na_dr, 1 /* on */);
+	if (ret) {
+		goto err_register;
+	}
+
+	nm_buf_size = NETMAP_BUF_SIZE(na_dr);
+
+	KASSERT(nm_buf_size > 0, ("Invalid netmap buffer size"));
+	sc->min_tx_space = PTNET_MAX_PKT_SIZE / nm_buf_size + 2;
+	device_printf(sc->dev, "%s: min_tx_space = %u\n", __func__,
+		      sc->min_tx_space);
+#ifdef PTNETMAP_STATS
+	callout_reset(&sc->tick, hz, ptnet_tick, sc);
+#endif
+
+	ifp->if_drv_flags |= IFF_DRV_RUNNING;
+
+	return 0;
+
+err_register:
+	memset(&na_dr->na_lut, 0, sizeof(na_dr->na_lut));
+err_get_lut:
+	netmap_mem_rings_delete(na_dr);
+err_rings_create:
+	ptnet_nm_krings_delete(na_nm);
+err_mem_finalize:
+	netmap_mem_deref(na_dr->nm_mem, na_dr);
+
+	return ret;
+}
+
+/* To be called under core lock. */
+static int
+ptnet_stop(struct ptnet_softc *sc)
+{
+	if_t ifp = sc->ifp;
+	struct netmap_adapter *na_dr = &sc->ptna->dr.up;
+	struct netmap_adapter *na_nm = &sc->ptna->hwup.up;
+	int i;
+
+	device_printf(sc->dev, "%s\n", __func__);
+
+	if (!(ifp->if_drv_flags & IFF_DRV_RUNNING)) {
+		return 0; /* nothing to do */
+	}
+
+	/* Clear the driver-ready flag, and synchronize with all the queues,
+	 * so that after this loop we are sure nobody is working anymore with
+	 * the device. This scheme is taken from the vtnet driver. */
+	ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
+	callout_stop(&sc->tick);
+	for (i = 0; i < sc->num_rings; i++) {
+		PTNET_Q_LOCK(sc->queues + i);
+		PTNET_Q_UNLOCK(sc->queues + i);
+	}
+
+	ptnet_nm_register(na_dr, 0 /* off */);
+
+	if (sc->ptna->backend_regifs == 0) {
+		netmap_mem_rings_delete(na_dr);
+		ptnet_nm_krings_delete(na_nm);
+	}
+	netmap_mem_deref(na_dr->nm_mem, na_dr);
+
+	return 0;
+}
+
+static void
+ptnet_qflush(if_t ifp)
+{
+	struct ptnet_softc *sc = if_getsoftc(ifp);
+	int i;
+
+	/* Flush all the bufrings and do the interface flush. */
+	for (i = 0; i < sc->num_rings; i++) {
+		struct ptnet_queue *pq = sc->queues + i;
+		struct mbuf *m;
+
+		PTNET_Q_LOCK(pq);
+		if (pq->bufring) {
+			while ((m = buf_ring_dequeue_sc(pq->bufring))) {
+				m_freem(m);
+			}
+		}
+		PTNET_Q_UNLOCK(pq);
+	}
+
+	if_qflush(ifp);
+}
+
+static int
+ptnet_media_change(if_t ifp)
+{
+	struct ptnet_softc *sc = if_getsoftc(ifp);
+	struct ifmedia *ifm = &sc->media;
+
+	if (IFM_TYPE(ifm->ifm_media) != IFM_ETHER) {
+		return EINVAL;
+	}
+
+	return 0;
+}
+
+#if __FreeBSD_version >= 1100000
+static uint64_t
+ptnet_get_counter(if_t ifp, ift_counter cnt)
+{
+	struct ptnet_softc *sc = if_getsoftc(ifp);
+	struct ptnet_queue_stats stats[2];
+	int i;
+
+	/* Accumulate statistics over the queues. */
+	memset(stats, 0, sizeof(stats));
+	for (i = 0; i < sc->num_rings; i++) {
+		struct ptnet_queue *pq = sc->queues + i;
+		int idx = (i < sc->num_tx_rings) ? 0 : 1;
+
+		stats[idx].packets	+= pq->stats.packets;
+		stats[idx].bytes	+= pq->stats.bytes;
+		stats[idx].errors	+= pq->stats.errors;
+		stats[idx].iqdrops	+= pq->stats.iqdrops;
+		stats[idx].mcasts	+= pq->stats.mcasts;
+	}
+
+	switch (cnt) {
+	case IFCOUNTER_IPACKETS:
+		return (stats[1].packets);
+	case IFCOUNTER_IQDROPS:
+		return (stats[1].iqdrops);
+	case IFCOUNTER_IERRORS:
+		return (stats[1].errors);
+	case IFCOUNTER_OPACKETS:
+		return (stats[0].packets);
+	case IFCOUNTER_OBYTES:
+		return (stats[0].bytes);
+	case IFCOUNTER_OMCASTS:
+		return (stats[0].mcasts);
+	default:
+		return (if_get_counter_default(ifp, cnt));
+	}
+}
+#endif
+
+
+#ifdef PTNETMAP_STATS
+/* Called under core lock. */
+static void
+ptnet_tick(void *opaque)
+{
+	struct ptnet_softc *sc = opaque;
+	int i;
+
+	for (i = 0; i < sc->num_rings; i++) {
+		struct ptnet_queue *pq = sc->queues + i;
+		struct ptnet_queue_stats cur = pq->stats;
+		struct timeval now;
+		unsigned int delta;
+
+		microtime(&now);
+		delta = now.tv_usec - sc->last_ts.tv_usec +
+			(now.tv_sec - sc->last_ts.tv_sec) * 1000000;
+		delta /= 1000; /* in milliseconds */
+
+		if (delta == 0)
+			continue;
+
+		device_printf(sc->dev, "#%d[%u ms]:pkts %lu, kicks %lu, "
+			      "intr %lu\n", i, delta,
+			      (cur.packets - pq->last_stats.packets),
+			      (cur.kicks - pq->last_stats.kicks),
+			      (cur.intrs - pq->last_stats.intrs));
+		pq->last_stats = cur;
+	}
+	microtime(&sc->last_ts);
+	callout_schedule(&sc->tick, hz);
+}
+#endif /* PTNETMAP_STATS */
+
+static void
+ptnet_media_status(if_t ifp, struct ifmediareq *ifmr)
+{
+	/* We are always active, as the backend netmap port is
+	 * always open in netmap mode. */
+	ifmr->ifm_status = IFM_AVALID | IFM_ACTIVE;
+	ifmr->ifm_active = IFM_ETHER | IFM_10G_T | IFM_FDX;
+}
+
+static uint32_t
+ptnet_nm_ptctl(if_t ifp, uint32_t cmd)
+{
+	struct ptnet_softc *sc = if_getsoftc(ifp);
+	int ret;
+
+	bus_write_4(sc->iomem, PTNET_IO_PTCTL, cmd);
+	ret = bus_read_4(sc->iomem, PTNET_IO_PTSTS);
+	device_printf(sc->dev, "PTCTL %u, ret %u\n", cmd, ret);
+
+	return ret;
+}
+
+static int
+ptnet_nm_config(struct netmap_adapter *na, unsigned *txr, unsigned *txd,
+		unsigned *rxr, unsigned *rxd)
+{
+	struct ptnet_softc *sc = if_getsoftc(na->ifp);
+
+	*txr = bus_read_4(sc->iomem, PTNET_IO_NUM_TX_RINGS);
+	*rxr = bus_read_4(sc->iomem, PTNET_IO_NUM_RX_RINGS);
+	*txd = bus_read_4(sc->iomem, PTNET_IO_NUM_TX_SLOTS);
+	*rxd = bus_read_4(sc->iomem, PTNET_IO_NUM_RX_SLOTS);
+
+	device_printf(sc->dev, "txr %u, rxr %u, txd %u, rxd %u\n",
+		      *txr, *rxr, *txd, *rxd);
+
+	return 0;
+}
+
+static void
+ptnet_sync_from_csb(struct ptnet_softc *sc, struct netmap_adapter *na)
+{
+	int i;
+
+	/* Sync krings from the host, reading from
+	 * CSB. */
+	for (i = 0; i < sc->num_rings; i++) {
+		struct ptnet_ring *ptring = sc->queues[i].ptring;
+		struct netmap_kring *kring;
+
+		if (i < na->num_tx_rings) {
+			kring = na->tx_rings + i;
+		} else {
+			kring = na->rx_rings + i - na->num_tx_rings;
+		}
+		kring->rhead = kring->ring->head = ptring->head;
+		kring->rcur = kring->ring->cur = ptring->cur;
+		kring->nr_hwcur = ptring->hwcur;
+		kring->nr_hwtail = kring->rtail =
+			kring->ring->tail = ptring->hwtail;
+
+		ND("%d,%d: csb {hc %u h %u c %u ht %u}", t, i,
+		   ptring->hwcur, ptring->head, ptring->cur,
+		   ptring->hwtail);
+		ND("%d,%d: kring {hc %u rh %u rc %u h %u c %u ht %u rt %u t %u}",
+		   t, i, kring->nr_hwcur, kring->rhead, kring->rcur,
+		   kring->ring->head, kring->ring->cur, kring->nr_hwtail,
+		   kring->rtail, kring->ring->tail);
+	}
+}
+
+static void
+ptnet_update_vnet_hdr(struct ptnet_softc *sc)
+{
+	sc->vnet_hdr_len = ptnet_vnet_hdr ? PTNET_HDR_SIZE : 0;
+	sc->ptna->hwup.up.virt_hdr_len = sc->vnet_hdr_len;
+	bus_write_4(sc->iomem, PTNET_IO_VNET_HDR_LEN, sc->vnet_hdr_len);
+}
+
+static int
+ptnet_nm_register(struct netmap_adapter *na, int onoff)
+{
+	/* device-specific */
+	if_t ifp = na->ifp;
+	struct ptnet_softc *sc = if_getsoftc(ifp);
+	int native = (na == &sc->ptna->hwup.up);
+	struct ptnet_queue *pq;
+	enum txrx t;
+	int ret = 0;
+	int i;
+
+	if (!onoff) {
+		sc->ptna->backend_regifs--;
+	}
+
+	/* If this is the last netmap client, guest interrupt enable flags may
+	 * be in arbitrary state. Since these flags are going to be used also
+	 * by the netdevice driver, we have to make sure to start with
+	 * notifications enabled. Also, schedule NAPI to flush pending packets
+	 * in the RX rings, since we will not receive further interrupts
+	 * until these will be processed. */
+	if (native && !onoff && na->active_fds == 0) {
+		D("Exit netmap mode, re-enable interrupts");
+		for (i = 0; i < sc->num_rings; i++) {
+			pq = sc->queues + i;
+			pq->ptring->guest_need_kick = 1;
+		}
+	}
+
+	if (onoff) {
+		if (sc->ptna->backend_regifs == 0) {
+			/* Initialize notification enable fields in the CSB. */
+			for (i = 0; i < sc->num_rings; i++) {
+				pq = sc->queues + i;
+				pq->ptring->host_need_kick = 1;
+				pq->ptring->guest_need_kick =
+					(!(ifp->if_capenable & IFCAP_POLLING)
+						&& i >= sc->num_tx_rings);
+			}
+
+			/* Set the virtio-net header length. */
+			ptnet_update_vnet_hdr(sc);
+
+			/* Make sure the host adapter passed through is ready
+			 * for txsync/rxsync. */
+			ret = ptnet_nm_ptctl(ifp, PTNETMAP_PTCTL_REGIF);
+			if (ret) {
+				return ret;
+			}
+		}
+
+		/* Sync from CSB must be done after REGIF PTCTL. Skip this
+		 * step only if this is a netmap client and it is not the
+		 * first one. */
+		if ((!native && sc->ptna->backend_regifs == 0) ||
+				(native && na->active_fds == 0)) {
+			ptnet_sync_from_csb(sc, na);
+		}
+
+		/* If not native, don't call nm_set_native_flags, since we don't want
+		 * to replace if_transmit method, nor set NAF_NETMAP_ON */
+		if (native) {
+			for_rx_tx(t) {
+				for (i = 0; i <= nma_get_nrings(na, t); i++) {
+					struct netmap_kring *kring = &NMR(na, t)[i];
+
+					if (nm_kring_pending_on(kring)) {
+						kring->nr_mode = NKR_NETMAP_ON;
+					}
+				}
+			}
+			nm_set_native_flags(na);
+		}
+
+	} else {
+		if (native) {
+			nm_clear_native_flags(na);
+			for_rx_tx(t) {
+				for (i = 0; i <= nma_get_nrings(na, t); i++) {
+					struct netmap_kring *kring = &NMR(na, t)[i];
+
+					if (nm_kring_pending_off(kring)) {
+						kring->nr_mode = NKR_NETMAP_OFF;
+					}
+				}
+			}
+		}
+
+		/* Sync from CSB must be done before UNREGIF PTCTL, on the last
+		 * netmap client. */
+		if (native && na->active_fds == 0) {
+			ptnet_sync_from_csb(sc, na);
+		}
+
+		if (sc->ptna->backend_regifs == 0) {
+			ret = ptnet_nm_ptctl(ifp, PTNETMAP_PTCTL_UNREGIF);
+		}
+	}
+
+	if (onoff) {
+		sc->ptna->backend_regifs++;
+	}
+
+	return ret;
+}
+
+static int
+ptnet_nm_txsync(struct netmap_kring *kring, int flags)
+{
+	struct ptnet_softc *sc = if_getsoftc(kring->na->ifp);
+	struct ptnet_queue *pq = sc->queues + kring->ring_id;
+	bool notify;
+
+	notify = netmap_pt_guest_txsync(pq->ptring, kring, flags);
+	if (notify) {
+		ptnet_kick(pq);
+	}
+
+	return 0;
+}
+
+static int
+ptnet_nm_rxsync(struct netmap_kring *kring, int flags)
+{
+	struct ptnet_softc *sc = if_getsoftc(kring->na->ifp);
+	struct ptnet_queue *pq = sc->rxqueues + kring->ring_id;
+	bool notify;
+
+	notify = netmap_pt_guest_rxsync(pq->ptring, kring, flags);
+	if (notify) {
+		ptnet_kick(pq);
+	}
+
+	return 0;
+}
+
+static void
+ptnet_tx_intr(void *opaque)
+{
+	struct ptnet_queue *pq = opaque;
+	struct ptnet_softc *sc = pq->sc;
+
+	DBG(device_printf(sc->dev, "Tx interrupt #%d\n", pq->kring_id));
+#ifdef PTNETMAP_STATS
+	pq->stats.intrs ++;
+#endif /* PTNETMAP_STATS */
+
+	if (netmap_tx_irq(sc->ifp, pq->kring_id) != NM_IRQ_PASS) {
+		return;
+	}
+
+	/* Schedule the tasqueue to flush process transmissions requests.
+	 * However, vtnet, if_em and if_igb just call ptnet_transmit() here,
+	 * at least when using MSI-X interrupts. The if_em driver, instead
+	 * schedule taskqueue when using legacy interrupts. */
+	taskqueue_enqueue(pq->taskq, &pq->task);
+}
+
+static void
+ptnet_rx_intr(void *opaque)
+{
+	struct ptnet_queue *pq = opaque;
+	struct ptnet_softc *sc = pq->sc;
+	unsigned int unused;
+
+	DBG(device_printf(sc->dev, "Rx interrupt #%d\n", pq->kring_id));
+#ifdef PTNETMAP_STATS
+	pq->stats.intrs ++;
+#endif /* PTNETMAP_STATS */
+
+	if (netmap_rx_irq(sc->ifp, pq->kring_id, &unused) != NM_IRQ_PASS) {
+		return;
+	}
+
+	/* Like vtnet, if_igb and if_em drivers when using MSI-X interrupts,
+	 * receive-side processing is executed directly in the interrupt
+	 * service routine. Alternatively, we may schedule the taskqueue. */
+	ptnet_rx_eof(pq, PTNET_RX_BUDGET, true);
+}
+
+/* The following offloadings-related functions are taken from the vtnet
+ * driver, but the same functionality is required for the ptnet driver.
+ * As a temporary solution, I copied this code from vtnet and I started
+ * to generalize it (taking away driver-specific statistic accounting),
+ * making as little modifications as possible.
+ * In the future we need to share these functions between vtnet and ptnet.
+ */
+static int
+ptnet_tx_offload_ctx(struct mbuf *m, int *etype, int *proto, int *start)
+{
+	struct ether_vlan_header *evh;
+	int offset;
+
+	evh = mtod(m, struct ether_vlan_header *);
+	if (evh->evl_encap_proto == htons(ETHERTYPE_VLAN)) {
+		/* BMV: We should handle nested VLAN tags too. */
+		*etype = ntohs(evh->evl_proto);
+		offset = sizeof(struct ether_vlan_header);
+	} else {
+		*etype = ntohs(evh->evl_encap_proto);
+		offset = sizeof(struct ether_header);
+	}
+
+	switch (*etype) {
+#if defined(INET)
+	case ETHERTYPE_IP: {
+		struct ip *ip, iphdr;
+		if (__predict_false(m->m_len < offset + sizeof(struct ip))) {
+			m_copydata(m, offset, sizeof(struct ip),
+			    (caddr_t) &iphdr);
+			ip = &iphdr;
+		} else
+			ip = (struct ip *)(m->m_data + offset);
+		*proto = ip->ip_p;
+		*start = offset + (ip->ip_hl << 2);
+		break;
+	}
+#endif
+#if defined(INET6)
+	case ETHERTYPE_IPV6:
+		*proto = -1;
+		*start = ip6_lasthdr(m, offset, IPPROTO_IPV6, proto);
+		/* Assert the network stack sent us a valid packet. */
+		KASSERT(*start > offset,
+		    ("%s: mbuf %p start %d offset %d proto %d", __func__, m,
+		    *start, offset, *proto));
+		break;
+#endif
+	default:
+		/* Here we should increment the tx_csum_bad_ethtype counter. */
+		return (EINVAL);
+	}
+
+	return (0);
+}
+
+static int
+ptnet_tx_offload_tso(if_t ifp, struct mbuf *m, int eth_type,
+		     int offset, bool allow_ecn, struct virtio_net_hdr *hdr)
+{
+	static struct timeval lastecn;
+	static int curecn;
+	struct tcphdr *tcp, tcphdr;
+
+	if (__predict_false(m->m_len < offset + sizeof(struct tcphdr))) {
+		m_copydata(m, offset, sizeof(struct tcphdr), (caddr_t) &tcphdr);
+		tcp = &tcphdr;
+	} else
+		tcp = (struct tcphdr *)(m->m_data + offset);
+
+	hdr->hdr_len = offset + (tcp->th_off << 2);
+	hdr->gso_size = m->m_pkthdr.tso_segsz;
+	hdr->gso_type = eth_type == ETHERTYPE_IP ? VIRTIO_NET_HDR_GSO_TCPV4 :
+	    VIRTIO_NET_HDR_GSO_TCPV6;
+
+	if (tcp->th_flags & TH_CWR) {
+		/*
+		 * Drop if VIRTIO_NET_F_HOST_ECN was not negotiated. In FreeBSD,
+		 * ECN support is not on a per-interface basis, but globally via
+		 * the net.inet.tcp.ecn.enable sysctl knob. The default is off.
+		 */
+		if (!allow_ecn) {
+			if (ppsratecheck(&lastecn, &curecn, 1))
+				if_printf(ifp,
+				    "TSO with ECN not negotiated with host\n");
+			return (ENOTSUP);
+		}
+		hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
+	}
+
+	/* Here we should increment tx_tso counter. */
+
+	return (0);
+}
+
+static struct mbuf *
+ptnet_tx_offload(if_t ifp, struct mbuf *m, bool allow_ecn,
+		 struct virtio_net_hdr *hdr)
+{
+	int flags, etype, csum_start, proto, error;
+
+	flags = m->m_pkthdr.csum_flags;
+
+	error = ptnet_tx_offload_ctx(m, &etype, &proto, &csum_start);
+	if (error)
+		goto drop;
+
+	if ((etype == ETHERTYPE_IP && flags & PTNET_CSUM_OFFLOAD) ||
+	    (etype == ETHERTYPE_IPV6 && flags & PTNET_CSUM_OFFLOAD_IPV6)) {
+		/*
+		 * We could compare the IP protocol vs the CSUM_ flag too,
+		 * but that really should not be necessary.
+		 */
+		hdr->flags |= VIRTIO_NET_HDR_F_NEEDS_CSUM;
+		hdr->csum_start = csum_start;
+		hdr->csum_offset = m->m_pkthdr.csum_data;
+		/* Here we should increment the tx_csum counter. */
+	}
+
+	if (flags & CSUM_TSO) {
+		if (__predict_false(proto != IPPROTO_TCP)) {
+			/* Likely failed to correctly parse the mbuf.
+			 * Here we should increment the tx_tso_not_tcp
+			 * counter. */
+			goto drop;
+		}
+
+		KASSERT(hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM,
+		    ("%s: mbuf %p TSO without checksum offload %#x",
+		    __func__, m, flags));
+
+		error = ptnet_tx_offload_tso(ifp, m, etype, csum_start,
+					     allow_ecn, hdr);
+		if (error)
+			goto drop;
+	}
+
+	return (m);
+
+drop:
+	m_freem(m);
+	return (NULL);
+}
+
+static void
+ptnet_vlan_tag_remove(struct mbuf *m)
+{
+	struct ether_vlan_header *evh;
+
+	evh = mtod(m, struct ether_vlan_header *);
+	m->m_pkthdr.ether_vtag = ntohs(evh->evl_tag);
+	m->m_flags |= M_VLANTAG;
+
+	/* Strip the 802.1Q header. */
+	bcopy((char *) evh, (char *) evh + ETHER_VLAN_ENCAP_LEN,
+	    ETHER_HDR_LEN - ETHER_TYPE_LEN);
+	m_adj(m, ETHER_VLAN_ENCAP_LEN);
+}
+
+/*
+ * Use the checksum offset in the VirtIO header to set the
+ * correct CSUM_* flags.
+ */
+static int
+ptnet_rx_csum_by_offset(struct mbuf *m, uint16_t eth_type, int ip_start,
+			struct virtio_net_hdr *hdr)
+{
+#if defined(INET) || defined(INET6)
+	int offset = hdr->csum_start + hdr->csum_offset;
+#endif
+
+	/* Only do a basic sanity check on the offset. */
+	switch (eth_type) {
+#if defined(INET)
+	case ETHERTYPE_IP:
+		if (__predict_false(offset < ip_start + sizeof(struct ip)))
+			return (1);
+		break;
+#endif
+#if defined(INET6)
+	case ETHERTYPE_IPV6:
+		if (__predict_false(offset < ip_start + sizeof(struct ip6_hdr)))
+			return (1);
+		break;
+#endif
+	default:
+		/* Here we should increment the rx_csum_bad_ethtype counter. */
+		return (1);
+	}
+
+	/*
+	 * Use the offset to determine the appropriate CSUM_* flags. This is
+	 * a bit dirty, but we can get by with it since the checksum offsets
+	 * happen to be different. We assume the host host does not do IPv4
+	 * header checksum offloading.
+	 */
+	switch (hdr->csum_offset) {
+	case offsetof(struct udphdr, uh_sum):
+	case offsetof(struct tcphdr, th_sum):
+		m->m_pkthdr.csum_flags |= CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
+		m->m_pkthdr.csum_data = 0xFFFF;
+		break;
+	case offsetof(struct sctphdr, checksum):
+		m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
+		break;
+	default:
+		/* Here we should increment the rx_csum_bad_offset counter. */
+		return (1);
+	}
+
+	return (0);
+}
+
+static int
+ptnet_rx_csum_by_parse(struct mbuf *m, uint16_t eth_type, int ip_start,
+		       struct virtio_net_hdr *hdr)
+{
+	int offset, proto;
+
+	switch (eth_type) {
+#if defined(INET)
+	case ETHERTYPE_IP: {
+		struct ip *ip;
+		if (__predict_false(m->m_len < ip_start + sizeof(struct ip)))
+			return (1);
+		ip = (struct ip *)(m->m_data + ip_start);
+		proto = ip->ip_p;
+		offset = ip_start + (ip->ip_hl << 2);
+		break;
+	}
+#endif
+#if defined(INET6)
+	case ETHERTYPE_IPV6:
+		if (__predict_false(m->m_len < ip_start +
+		    sizeof(struct ip6_hdr)))
+			return (1);
+		offset = ip6_lasthdr(m, ip_start, IPPROTO_IPV6, &proto);
+		if (__predict_false(offset < 0))
+			return (1);
+		break;
+#endif
+	default:
+		/* Here we should increment the rx_csum_bad_ethtype counter. */
+		return (1);
+	}
+
+	switch (proto) {
+	case IPPROTO_TCP:
+		if (__predict_false(m->m_len < offset + sizeof(struct tcphdr)))
+			return (1);
+		m->m_pkthdr.csum_flags |= CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
+		m->m_pkthdr.csum_data = 0xFFFF;
+		break;
+	case IPPROTO_UDP:
+		if (__predict_false(m->m_len < offset + sizeof(struct udphdr)))
+			return (1);
+		m->m_pkthdr.csum_flags |= CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
+		m->m_pkthdr.csum_data = 0xFFFF;
+		break;
+	case IPPROTO_SCTP:
+		if (__predict_false(m->m_len < offset + sizeof(struct sctphdr)))
+			return (1);
+		m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
+		break;
+	default:
+		/*
+		 * For the remaining protocols, FreeBSD does not support
+		 * checksum offloading, so the checksum will be recomputed.
+		 */
+#if 0
+		if_printf(ifp, "cksum offload of unsupported "
+		    "protocol eth_type=%#x proto=%d csum_start=%d "
+		    "csum_offset=%d\n", __func__, eth_type, proto,
+		    hdr->csum_start, hdr->csum_offset);
+#endif
+		break;
+	}
+
+	return (0);
+}
+
+/*
+ * Set the appropriate CSUM_* flags. Unfortunately, the information
+ * provided is not directly useful to us. The VirtIO header gives the
+ * offset of the checksum, which is all Linux needs, but this is not
+ * how FreeBSD does things. We are forced to peek inside the packet
+ * a bit.
+ *
+ * It would be nice if VirtIO gave us the L4 protocol or if FreeBSD
+ * could accept the offsets and let the stack figure it out.
+ */
+static int
+ptnet_rx_csum(struct mbuf *m, struct virtio_net_hdr *hdr)
+{
+	struct ether_header *eh;
+	struct ether_vlan_header *evh;
+	uint16_t eth_type;
+	int offset, error;
+
+	eh = mtod(m, struct ether_header *);
+	eth_type = ntohs(eh->ether_type);
+	if (eth_type == ETHERTYPE_VLAN) {
+		/* BMV: We should handle nested VLAN tags too. */
+		evh = mtod(m, struct ether_vlan_header *);
+		eth_type = ntohs(evh->evl_proto);
+		offset = sizeof(struct ether_vlan_header);
+	} else
+		offset = sizeof(struct ether_header);
+
+	if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM)
+		error = ptnet_rx_csum_by_offset(m, eth_type, offset, hdr);
+	else
+		error = ptnet_rx_csum_by_parse(m, eth_type, offset, hdr);
+
+	return (error);
+}
+/* End of offloading-related functions to be shared with vtnet. */
+
+static inline void
+ptnet_sync_tail(struct ptnet_ring *ptring, struct netmap_kring *kring)
+{
+	struct netmap_ring *ring = kring->ring;
+
+	/* Update hwcur and hwtail as known by the host. */
+        ptnetmap_guest_read_kring_csb(ptring, kring);
+
+	/* nm_sync_finalize */
+	ring->tail = kring->rtail = kring->nr_hwtail;
+}
+
+static void
+ptnet_ring_update(struct ptnet_queue *pq, struct netmap_kring *kring,
+		  unsigned int head, unsigned int sync_flags)
+{
+	struct netmap_ring *ring = kring->ring;
+	struct ptnet_ring *ptring = pq->ptring;
+
+	/* Some packets have been pushed to the netmap ring. We have
+	 * to tell the host to process the new packets, updating cur
+	 * and head in the CSB. */
+	ring->head = ring->cur = head;
+
+	/* Mimic nm_txsync_prologue/nm_rxsync_prologue. */
+	kring->rcur = kring->rhead = head;
+
+	ptnetmap_guest_write_kring_csb(ptring, kring->rcur, kring->rhead);
+
+	/* Kick the host if needed. */
+	if (NM_ACCESS_ONCE(ptring->host_need_kick)) {
+		ptring->sync_flags = sync_flags;
+		ptnet_kick(pq);
+	}
+}
+
+#define PTNET_TX_NOSPACE(_h, _k, _min)	\
+	((((_h) < (_k)->rtail) ? 0 : (_k)->nkr_num_slots) + \
+		(_k)->rtail - (_h)) < (_min)
+
+/* This function may be called by the network stack, or by
+ * by the taskqueue thread. */
+static int
+ptnet_drain_transmit_queue(struct ptnet_queue *pq, unsigned int budget,
+			   bool may_resched)
+{
+	struct ptnet_softc *sc = pq->sc;
+	bool have_vnet_hdr = sc->vnet_hdr_len;
+	struct netmap_adapter *na = &sc->ptna->dr.up;
+	if_t ifp = sc->ifp;
+	unsigned int batch_count = 0;
+	struct ptnet_ring *ptring;
+	struct netmap_kring *kring;
+	struct netmap_ring *ring;
+	struct netmap_slot *slot;
+	unsigned int count = 0;
+	unsigned int minspace;
+	unsigned int head;
+	unsigned int lim;
+	struct mbuf *mhead;
+	struct mbuf *mf;
+	int nmbuf_bytes;
+	uint8_t *nmbuf;
+
+	if (!PTNET_Q_TRYLOCK(pq)) {
+		/* We failed to acquire the lock, schedule the taskqueue. */
+		RD(1, "Deferring TX work");
+		if (may_resched) {
+			taskqueue_enqueue(pq->taskq, &pq->task);
+		}
+
+		return 0;
+	}
+
+	if (unlikely(!(ifp->if_drv_flags & IFF_DRV_RUNNING))) {
+		PTNET_Q_UNLOCK(pq);
+		RD(1, "Interface is down");
+		return ENETDOWN;
+	}
+
+	ptring = pq->ptring;
+	kring = na->tx_rings + pq->kring_id;
+	ring = kring->ring;
+	lim = kring->nkr_num_slots - 1;
+	head = ring->head;
+	minspace = sc->min_tx_space;
+
+	while (count < budget) {
+		if (PTNET_TX_NOSPACE(head, kring, minspace)) {
+			/* We ran out of slot, let's see if the host has
+			 * freed up some, by reading hwcur and hwtail from
+			 * the CSB. */
+			ptnet_sync_tail(ptring, kring);
+
+			if (PTNET_TX_NOSPACE(head, kring, minspace)) {
+				/* Still no slots available. Reactivate the
+				 * interrupts so that we can be notified
+				 * when some free slots are made available by
+				 * the host. */
+				ptring->guest_need_kick = 1;
+
+				/* Double-check. */
+				ptnet_sync_tail(ptring, kring);
+				if (likely(PTNET_TX_NOSPACE(head, kring,
+							    minspace))) {
+					break;
+				}
+
+				RD(1, "Found more slots by doublecheck");
+				/* More slots were freed before reactivating
+				 * the interrupts. */
+				ptring->guest_need_kick = 0;
+			}
+		}
+
+		mhead = drbr_peek(ifp, pq->bufring);
+		if (!mhead) {
+			break;
+		}
+
+		/* Initialize transmission state variables. */
+		slot = ring->slot + head;
+		nmbuf = NMB(na, slot);
+		nmbuf_bytes = 0;
+
+		/* If needed, prepare the virtio-net header at the beginning
+		 * of the first slot. */
+		if (have_vnet_hdr) {
+			struct virtio_net_hdr *vh =
+					(struct virtio_net_hdr *)nmbuf;
+
+			/* For performance, we could replace this memset() with
+			 * two 8-bytes-wide writes. */
+			memset(nmbuf, 0, PTNET_HDR_SIZE);
+			if (mhead->m_pkthdr.csum_flags & PTNET_ALL_OFFLOAD) {
+				mhead = ptnet_tx_offload(ifp, mhead, false,
+							 vh);
+				if (unlikely(!mhead)) {
+					/* Packet dropped because errors
+					 * occurred while preparing the vnet
+					 * header. Let's go ahead with the next
+					 * packet. */
+					pq->stats.errors ++;
+					drbr_advance(ifp, pq->bufring);
+					continue;
+				}
+			}
+			ND(1, "%s: [csum_flags %lX] vnet hdr: flags %x "
+			      "csum_start %u csum_ofs %u hdr_len = %u "
+			      "gso_size %u gso_type %x", __func__,
+			      mhead->m_pkthdr.csum_flags, vh->flags,
+			      vh->csum_start, vh->csum_offset, vh->hdr_len,
+			      vh->gso_size, vh->gso_type);
+
+			nmbuf += PTNET_HDR_SIZE;
+			nmbuf_bytes += PTNET_HDR_SIZE;
+		}
+
+		for (mf = mhead; mf; mf = mf->m_next) {
+			uint8_t *mdata = mf->m_data;
+			int mlen = mf->m_len;
+
+			for (;;) {
+				int copy = NETMAP_BUF_SIZE(na) - nmbuf_bytes;
+
+				if (mlen < copy) {
+					copy = mlen;
+				}
+				memcpy(nmbuf, mdata, copy);
+
+				mdata += copy;
+				mlen -= copy;
+				nmbuf += copy;
+				nmbuf_bytes += copy;
+
+				if (!mlen) {
+					break;
+				}
+
+				slot->len = nmbuf_bytes;
+				slot->flags = NS_MOREFRAG;
+
+				head = nm_next(head, lim);
+				KASSERT(head != ring->tail,
+					("Unexpectedly run out of TX space"));
+				slot = ring->slot + head;
+				nmbuf = NMB(na, slot);
+				nmbuf_bytes = 0;
+			}
+		}
+
+		/* Complete last slot and update head. */
+		slot->len = nmbuf_bytes;
+		slot->flags = 0;
+		head = nm_next(head, lim);
+
+		/* Consume the packet just processed. */
+		drbr_advance(ifp, pq->bufring);
+
+		/* Copy the packet to listeners. */
+		ETHER_BPF_MTAP(ifp, mhead);
+
+		pq->stats.packets ++;
+		pq->stats.bytes += mhead->m_pkthdr.len;
+		if (mhead->m_flags & M_MCAST) {
+			pq->stats.mcasts ++;
+		}
+
+		m_freem(mhead);
+
+		count ++;
+		if (++batch_count == PTNET_TX_BATCH) {
+			ptnet_ring_update(pq, kring, head, NAF_FORCE_RECLAIM);
+			batch_count = 0;
+		}
+	}
+
+	if (batch_count) {
+		ptnet_ring_update(pq, kring, head, NAF_FORCE_RECLAIM);
+	}
+
+	if (count >= budget && may_resched) {
+		DBG(RD(1, "out of budget: resched, %d mbufs pending\n",
+					drbr_inuse(ifp, pq->bufring)));
+		taskqueue_enqueue(pq->taskq, &pq->task);
+	}
+
+	PTNET_Q_UNLOCK(pq);
+
+	return count;
+}
+
+static int
+ptnet_transmit(if_t ifp, struct mbuf *m)
+{
+	struct ptnet_softc *sc = if_getsoftc(ifp);
+	struct ptnet_queue *pq;
+	unsigned int queue_idx;
+	int err;
+
+	DBG(device_printf(sc->dev, "transmit %p\n", m));
+
+	/* Insert 802.1Q header if needed. */
+	if (m->m_flags & M_VLANTAG) {
+		m = ether_vlanencap(m, m->m_pkthdr.ether_vtag);
+		if (m == NULL) {
+			return ENOBUFS;
+		}
+		m->m_flags &= ~M_VLANTAG;
+	}
+
+	/* Get the flow-id if available. */
+	queue_idx = (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) ?
+		    m->m_pkthdr.flowid : curcpu;
+
+	if (unlikely(queue_idx >= sc->num_tx_rings)) {
+		queue_idx %= sc->num_tx_rings;
+	}
+
+	pq = sc->queues + queue_idx;
+
+	err = drbr_enqueue(ifp, pq->bufring, m);
+	if (err) {
+		/* ENOBUFS when the bufring is full */
+		RD(1, "%s: drbr_enqueue() failed %d\n",
+			__func__, err);
+		pq->stats.errors ++;
+		return err;
+	}
+
+	if (ifp->if_capenable & IFCAP_POLLING) {
+		/* If polling is on, the transmit queues will be
+		 * drained by the poller. */
+		return 0;
+	}
+
+	err = ptnet_drain_transmit_queue(pq, PTNET_TX_BUDGET, true);
+
+	return (err < 0) ? err : 0;
+}
+
+static unsigned int
+ptnet_rx_discard(struct netmap_kring *kring, unsigned int head)
+{
+	struct netmap_ring *ring = kring->ring;
+	struct netmap_slot *slot = ring->slot + head;
+
+	for (;;) {
+		head = nm_next(head, kring->nkr_num_slots - 1);
+		if (!(slot->flags & NS_MOREFRAG) || head == ring->tail) {
+			break;
+		}
+		slot = ring->slot + head;
+	}
+
+	return head;
+}
+
+static inline struct mbuf *
+ptnet_rx_slot(struct mbuf *mtail, uint8_t *nmbuf, unsigned int nmbuf_len)
+{
+	uint8_t *mdata = mtod(mtail, uint8_t *) + mtail->m_len;
+
+	do {
+		unsigned int copy;
+
+		if (mtail->m_len == MCLBYTES) {
+			struct mbuf *mf;
+
+			mf = m_getcl(M_NOWAIT, MT_DATA, 0);
+			if (unlikely(!mf)) {
+				return NULL;
+			}
+
+			mtail->m_next = mf;
+			mtail = mf;
+			mdata = mtod(mtail, uint8_t *);
+			mtail->m_len = 0;
+		}
+
+		copy = MCLBYTES - mtail->m_len;
+		if (nmbuf_len < copy) {
+			copy = nmbuf_len;
+		}
+
+		memcpy(mdata, nmbuf, copy);
+
+		nmbuf += copy;
+		nmbuf_len -= copy;
+		mdata += copy;
+		mtail->m_len += copy;
+	} while (nmbuf_len);
+
+	return mtail;
+}
+
+static int
+ptnet_rx_eof(struct ptnet_queue *pq, unsigned int budget, bool may_resched)
+{
+	struct ptnet_softc *sc = pq->sc;
+	bool have_vnet_hdr = sc->vnet_hdr_len;
+	struct ptnet_ring *ptring = pq->ptring;
+	struct netmap_adapter *na = &sc->ptna->dr.up;
+	struct netmap_kring *kring = na->rx_rings + pq->kring_id;
+	struct netmap_ring *ring = kring->ring;
+	unsigned int const lim = kring->nkr_num_slots - 1;
+	unsigned int head = ring->head;
+	unsigned int batch_count = 0;
+	if_t ifp = sc->ifp;
+	unsigned int count = 0;
+
+	PTNET_Q_LOCK(pq);
+
+	if (unlikely(!(ifp->if_drv_flags & IFF_DRV_RUNNING))) {
+		goto unlock;
+	}
+
+	kring->nr_kflags &= ~NKR_PENDINTR;
+
+	while (count < budget) {
+		unsigned int prev_head = head;
+		struct mbuf *mhead, *mtail;
+		struct virtio_net_hdr *vh;
+		struct netmap_slot *slot;
+		unsigned int nmbuf_len;
+		uint8_t *nmbuf;
+host_sync:
+		if (head == ring->tail) {
+			/* We ran out of slot, let's see if the host has
+			 * added some, by reading hwcur and hwtail from
+			 * the CSB. */
+			ptnet_sync_tail(ptring, kring);
+
+			if (head == ring->tail) {
+				/* Still no slots available. Reactivate
+				 * interrupts as they were disabled by the
+				 * host thread right before issuing the
+				 * last interrupt. */
+				ptring->guest_need_kick = 1;
+
+				/* Double-check. */
+				ptnet_sync_tail(ptring, kring);
+				if (likely(head == ring->tail)) {
+					break;
+				}
+				ptring->guest_need_kick = 0;
+			}
+		}
+
+		/* Initialize ring state variables, possibly grabbing the
+		 * virtio-net header. */
+		slot = ring->slot + head;
+		nmbuf = NMB(na, slot);
+		nmbuf_len = slot->len;
+
+		vh = (struct virtio_net_hdr *)nmbuf;
+		if (have_vnet_hdr) {
+			if (unlikely(nmbuf_len < PTNET_HDR_SIZE)) {
+				/* There is no good reason why host should
+				 * put the header in multiple netmap slots.
+				 * If this is the case, discard. */
+				RD(1, "Fragmented vnet-hdr: dropping");
+				head = ptnet_rx_discard(kring, head);
+				pq->stats.iqdrops ++;
+				goto skip;
+			}
+			ND(1, "%s: vnet hdr: flags %x csum_start %u "
+			      "csum_ofs %u hdr_len = %u gso_size %u "
+			      "gso_type %x", __func__, vh->flags,
+			      vh->csum_start, vh->csum_offset, vh->hdr_len,
+			      vh->gso_size, vh->gso_type);
+			nmbuf += PTNET_HDR_SIZE;
+			nmbuf_len -= PTNET_HDR_SIZE;
+		}
+
+		/* Allocate the head of a new mbuf chain.
+		 * We use m_getcl() to allocate an mbuf with standard cluster
+		 * size (MCLBYTES). In the future we could use m_getjcl()
+		 * to choose different sizes. */
+		mhead = mtail = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
+		if (unlikely(mhead == NULL)) {
+			device_printf(sc->dev, "%s: failed to allocate mbuf "
+				      "head\n", __func__);
+			pq->stats.errors ++;
+			break;
+		}
+
+		/* Initialize the mbuf state variables. */
+		mhead->m_pkthdr.len = nmbuf_len;
+		mtail->m_len = 0;
+
+		/* Scan all the netmap slots containing the current packet. */
+		for (;;) {
+			DBG(device_printf(sc->dev, "%s: h %u t %u rcv frag "
+					  "len %u, flags %u\n", __func__,
+					  head, ring->tail, slot->len,
+					  slot->flags));
+
+			mtail = ptnet_rx_slot(mtail, nmbuf, nmbuf_len);
+			if (unlikely(!mtail)) {
+				/* Ouch. We ran out of memory while processing
+				 * a packet. We have to restore the previous
+				 * head position, free the mbuf chain, and
+				 * schedule the taskqueue to give the packet
+				 * another chance. */
+				device_printf(sc->dev, "%s: failed to allocate"
+					" mbuf frag, reset head %u --> %u\n",
+					__func__, head, prev_head);
+				head = prev_head;
+				m_freem(mhead);
+				pq->stats.errors ++;
+				if (may_resched) {
+					taskqueue_enqueue(pq->taskq,
+							  &pq->task);
+				}
+				goto escape;
+			}
+
+			/* We have to increment head irrespective of the
+			 * NS_MOREFRAG being set or not. */
+			head = nm_next(head, lim);
+
+			if (!(slot->flags & NS_MOREFRAG)) {
+				break;
+			}
+
+			if (unlikely(head == ring->tail)) {
+				/* The very last slot prepared by the host has
+				 * the NS_MOREFRAG set. Drop it and continue
+				 * the outer cycle (to do the double-check). */
+				RD(1, "Incomplete packet: dropping");
+				m_freem(mhead);
+				pq->stats.iqdrops ++;
+				goto host_sync;
+			}
+
+			slot = ring->slot + head;
+			nmbuf = NMB(na, slot);
+			nmbuf_len = slot->len;
+			mhead->m_pkthdr.len += nmbuf_len;
+		}
+
+		mhead->m_pkthdr.rcvif = ifp;
+		mhead->m_pkthdr.csum_flags = 0;
+
+		/* Store the queue idx in the packet header. */
+		mhead->m_pkthdr.flowid = pq->kring_id;
+		M_HASHTYPE_SET(mhead, M_HASHTYPE_OPAQUE);
+
+		if (ifp->if_capenable & IFCAP_VLAN_HWTAGGING) {
+			struct ether_header *eh;
+
+			eh = mtod(mhead, struct ether_header *);
+			if (eh->ether_type == htons(ETHERTYPE_VLAN)) {
+				ptnet_vlan_tag_remove(mhead);
+				/*
+				 * With the 802.1Q header removed, update the
+				 * checksum starting location accordingly.
+				 */
+				if (vh->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM)
+					vh->csum_start -= ETHER_VLAN_ENCAP_LEN;
+			}
+		}
+
+		if (have_vnet_hdr && (vh->flags & (VIRTIO_NET_HDR_F_NEEDS_CSUM
+					| VIRTIO_NET_HDR_F_DATA_VALID))) {
+			if (unlikely(ptnet_rx_csum(mhead, vh))) {
+				m_freem(mhead);
+				RD(1, "Csum offload error: dropping");
+				pq->stats.iqdrops ++;
+				goto skip;
+			}
+		}
+
+		pq->stats.packets ++;
+		pq->stats.bytes += mhead->m_pkthdr.len;
+
+		PTNET_Q_UNLOCK(pq);
+		(*ifp->if_input)(ifp, mhead);
+		PTNET_Q_LOCK(pq);
+
+		if (unlikely(!(ifp->if_drv_flags & IFF_DRV_RUNNING))) {
+			/* The interface has gone down while we didn't
+			 * have the lock. Stop any processing and exit. */
+			goto unlock;
+		}
+skip:
+		count ++;
+		if (++batch_count == PTNET_RX_BATCH) {
+			/* Some packets have been pushed to the network stack.
+			 * We need to update the CSB to tell the host about the new
+			 * ring->cur and ring->head (RX buffer refill). */
+			ptnet_ring_update(pq, kring, head, NAF_FORCE_READ);
+			batch_count = 0;
+		}
+	}
+escape:
+	if (batch_count) {
+		ptnet_ring_update(pq, kring, head, NAF_FORCE_READ);
+
+	}
+
+	if (count >= budget && may_resched) {
+		/* If we ran out of budget or the double-check found new
+		 * slots to process, schedule the taskqueue. */
+		DBG(RD(1, "out of budget: resched h %u t %u\n",
+					head, ring->tail));
+		taskqueue_enqueue(pq->taskq, &pq->task);
+	}
+unlock:
+	PTNET_Q_UNLOCK(pq);
+
+	return count;
+}
+
+static void
+ptnet_rx_task(void *context, int pending)
+{
+	struct ptnet_queue *pq = context;
+
+	DBG(RD(1, "%s: pq #%u\n", __func__, pq->kring_id));
+	ptnet_rx_eof(pq, PTNET_RX_BUDGET, true);
+}
+
+static void
+ptnet_tx_task(void *context, int pending)
+{
+	struct ptnet_queue *pq = context;
+
+	DBG(RD(1, "%s: pq #%u\n", __func__, pq->kring_id));
+	ptnet_drain_transmit_queue(pq, PTNET_TX_BUDGET, true);
+}
+
+#ifdef DEVICE_POLLING
+/* We don't need to handle differently POLL_AND_CHECK_STATUS and
+ * POLL_ONLY, since we don't have an Interrupt Status Register. */
+static int
+ptnet_poll(if_t ifp, enum poll_cmd cmd, int budget)
+{
+	struct ptnet_softc *sc = if_getsoftc(ifp);
+	unsigned int queue_budget;
+	unsigned int count = 0;
+	bool borrow = false;
+	int i;
+
+	KASSERT(sc->num_rings > 0, ("Found no queues in while polling ptnet"));
+	queue_budget = MAX(budget / sc->num_rings, 1);
+	RD(1, "Per-queue budget is %d", queue_budget);
+
+	while (budget) {
+		unsigned int rcnt = 0;
+
+		for (i = 0; i < sc->num_rings; i++) {
+			struct ptnet_queue *pq = sc->queues + i;
+
+			if (borrow) {
+				queue_budget = MIN(queue_budget, budget);
+				if (queue_budget == 0) {
+					break;
+				}
+			}
+
+			if (i < sc->num_tx_rings) {
+				rcnt += ptnet_drain_transmit_queue(pq,
+						   queue_budget, false);
+			} else {
+				rcnt += ptnet_rx_eof(pq, queue_budget,
+						      false);
+			}
+		}
+
+		if (!rcnt) {
+			/* A scan of the queues gave no result, we can
+			 * stop here. */
+			break;
+		}
+
+		if (rcnt > budget) {
+			/* This may happen when initial budget < sc->num_rings,
+			 * since one packet budget is given to each queue
+			 * anyway. Just pretend we didn't eat "so much". */
+			rcnt = budget;
+		}
+		count += rcnt;
+		budget -= rcnt;
+		borrow = true;
+	}
+
+
+	return count;
+}
+#endif /* DEVICE_POLLING */