xref: /src/sys/dev/pci/ixgbe/ixgbe_netmap.c

/* $NetBSD: ixgbe_netmap.c,v 1.6 2023/10/06 14:37:04 msaitoh Exp $ */
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/*$FreeBSD: head/sys/dev/ixgbe/ixgbe_netmap.c 320688 2017-07-05 17:27:03Z erj $*/

/*
 * Copyright (C) 2011-2014 Matteo Landi, Luigi Rizzo. 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, 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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: head/sys/dev/ixgbe/ixgbe_netmap.c 320688 2017-07-05 17:27:03Z erj $
 *
 * netmap support for: ixgbe
 *
 * This file is meant to be a reference on how to implement
 * netmap support for a network driver.
 * This file contains code but only static or inline functions used
 * by a single driver. To avoid replication of code we just #include
 * it near the beginning of the standard driver.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ixgbe_netmap.c,v 1.6 2023/10/06 14:37:04 msaitoh Exp $");

#ifdef DEV_NETMAP
/*
 * Some drivers may need the following headers. Others
 * already include them by default

#include <vm/vm.h>
#include <vm/pmap.h>

 */
#include "ixgbe.h"

/*
 * device-specific sysctl variables:
 *
 * ix_crcstrip: 0: keep CRC in rx frames (default), 1: strip it.
 *	During regular operations the CRC is stripped, but on some
 *	hardware reception of frames not multiple of 64 is slower,
 *	so using crcstrip=0 helps in benchmarks.
 *
 * ix_rx_miss, ix_rx_miss_bufs:
 *	count packets that might be missed due to lost interrupts.
 */
SYSCTL_DECL(_dev_netmap);
static int ix_rx_miss, ix_rx_miss_bufs;
int ix_crcstrip;
SYSCTL_INT(_dev_netmap, OID_AUTO, ix_crcstrip,
    CTLFLAG_RW, &ix_crcstrip, 0, "strip CRC on rx frames");
SYSCTL_INT(_dev_netmap, OID_AUTO, ix_rx_miss,
    CTLFLAG_RW, &ix_rx_miss, 0, "potentially missed rx intr");
SYSCTL_INT(_dev_netmap, OID_AUTO, ix_rx_miss_bufs,
    CTLFLAG_RW, &ix_rx_miss_bufs, 0, "potentially missed rx intr bufs");


static void
set_crcstrip(struct ixgbe_hw *hw, int onoff)
{
	/* crc stripping is set in two places:
	 * IXGBE_HLREG0 (modified on init_locked and hw reset)
	 * IXGBE_RDRXCTL (set by the original driver in
	 *	ixgbe_setup_hw_rsc() called in init_locked.
	 *	We disable the setting when netmap is compiled in).
	 * We update the values here, but also in ixgbe.c because
	 * init_locked sometimes is called outside our control.
	 */
	uint32_t hl, rxc;

	hl = IXGBE_READ_REG(hw, IXGBE_HLREG0);
	rxc = IXGBE_READ_REG(hw, IXGBE_RDRXCTL);
#ifdef D
	if (netmap_verbose)
		D("%s read  HLREG 0x%x rxc 0x%x",
			onoff ? "enter" : "exit", hl, rxc);
#endif
	/* hw requirements ... */
	rxc &= ~IXGBE_RDRXCTL_RSCFRSTSIZE;
	rxc |= IXGBE_RDRXCTL_RSCACKC;
	if (onoff && !ix_crcstrip) {
		/* keep the crc. Fast rx */
		hl &= ~IXGBE_HLREG0_RXCRCSTRP;
		rxc &= ~IXGBE_RDRXCTL_CRCSTRIP;
	} else {
		/* reset default mode */
		hl |= IXGBE_HLREG0_RXCRCSTRP;
		rxc |= IXGBE_RDRXCTL_CRCSTRIP;
	}
#ifdef D
	if (netmap_verbose)
		D("%s write HLREG 0x%x rxc 0x%x",
			onoff ? "enter" : "exit", hl, rxc);
#endif
	IXGBE_WRITE_REG(hw, IXGBE_HLREG0, hl);
	IXGBE_WRITE_REG(hw, IXGBE_RDRXCTL, rxc);
}


/*
 * Register/unregister. We are already under netmap lock.
 * Only called on the first register or the last unregister.
 */
static int
ixgbe_netmap_reg(struct netmap_adapter *na, int onoff)
{
	struct ifnet *ifp = na->ifp;
	struct ixgbe_softc *sc = ifp->if_softc;

	IXGBE_CORE_LOCK(sc);
	sc->stop_locked(sc);

	set_crcstrip(&sc->hw, onoff);
	/* enable or disable flags and callbacks in na and ifp */
	if (onoff) {
		nm_set_native_flags(na);
	} else {
		nm_clear_native_flags(na);
	}
	sc->init_locked(sc);	/* also enables intr */
	set_crcstrip(&sc->hw, onoff); // XXX why twice ?
	IXGBE_CORE_UNLOCK(sc);
	return (ifp->if_drv_flags & IFF_DRV_RUNNING ? 0 : 1);
}


/*
 * Reconcile kernel and user view of the transmit ring.
 *
 * All information is in the kring.
 * Userspace wants to send packets up to the one before kring->rhead,
 * kernel knows kring->nr_hwcur is the first unsent packet.
 *
 * Here we push packets out (as many as possible), and possibly
 * reclaim buffers from previously completed transmission.
 *
 * The caller (netmap) guarantees that there is only one instance
 * running at any time. Any interference with other driver
 * methods should be handled by the individual drivers.
 */
static int
ixgbe_netmap_txsync(struct netmap_kring *kring, int flags)
{
	struct netmap_adapter *na = kring->na;
	struct ifnet *ifp = na->ifp;
	struct netmap_ring *ring = kring->ring;
	u_int nm_i;	/* index into the netmap ring */
	u_int nic_i;	/* index into the NIC ring */
	u_int n;
	u_int const lim = kring->nkr_num_slots - 1;
	u_int const head = kring->rhead;
	/*
	 * interrupts on every tx packet are expensive so request
	 * them every half ring, or where NS_REPORT is set
	 */
	u_int report_frequency = kring->nkr_num_slots >> 1;

	/* device-specific */
	struct ixgbe_softc *sc = ifp->if_softc;
	struct tx_ring *txr = &sc->tx_rings[kring->ring_id];
	int reclaim_tx;

	bus_dmamap_sync(txr->txdma.dma_tag, txr->txdma.dma_map,
			BUS_DMASYNC_POSTREAD);

	/*
	 * First part: process new packets to send.
	 * nm_i is the current index in the netmap ring,
	 * nic_i is the corresponding index in the NIC ring.
	 * The two numbers differ because upon a *_init() we reset
	 * the NIC ring but leave the netmap ring unchanged.
	 * For the transmit ring, we have
	 *
	 *		nm_i = kring->nr_hwcur
	 *		nic_i = IXGBE_TDT (not tracked in the driver)
	 * and
	 * 		nm_i == (nic_i + kring->nkr_hwofs) % ring_size
	 *
	 * In this driver kring->nkr_hwofs >= 0, but for other
	 * drivers it might be negative as well.
	 */

	/*
	 * If we have packets to send (kring->nr_hwcur != kring->rhead)
	 * iterate over the netmap ring, fetch length and update
	 * the corresponding slot in the NIC ring. Some drivers also
	 * need to update the buffer's physical address in the NIC slot
	 * even NS_BUF_CHANGED is not set (PNMB computes the addresses).
	 *
	 * The netmap_reload_map() calls is especially expensive,
	 * even when (as in this case) the tag is 0, so do only
	 * when the buffer has actually changed.
	 *
	 * If possible do not set the report/intr bit on all slots,
	 * but only a few times per ring or when NS_REPORT is set.
	 *
	 * Finally, on 10G and faster drivers, it might be useful
	 * to prefetch the next slot and txr entry.
	 */

	nm_i = kring->nr_hwcur;
	if (nm_i != head) {	/* we have new packets to send */
		nic_i = netmap_idx_k2n(kring, nm_i);

		__builtin_prefetch(&ring->slot[nm_i]);
		__builtin_prefetch(&txr->tx_buffers[nic_i]);

		for (n = 0; nm_i != head; n++) {
			struct netmap_slot *slot = &ring->slot[nm_i];
			u_int len = slot->len;
			uint64_t paddr;
			void *addr = PNMB(na, slot, &paddr);

			/* device-specific */
			union ixgbe_adv_tx_desc *curr = &txr->tx_base[nic_i];
			struct ixgbe_tx_buf *txbuf = &txr->tx_buffers[nic_i];
			int flags = (slot->flags & NS_REPORT ||
				nic_i == 0 || nic_i == report_frequency) ?
				IXGBE_TXD_CMD_RS : 0;

			/* prefetch for next round */
			__builtin_prefetch(&ring->slot[nm_i + 1]);
			__builtin_prefetch(&txr->tx_buffers[nic_i + 1]);

			NM_CHECK_ADDR_LEN(na, addr, len);

			if (slot->flags & NS_BUF_CHANGED) {
				/* buffer has changed, reload map */
				netmap_reload_map(na, txr->txtag, txbuf->map, addr);
			}
			slot->flags &= ~(NS_REPORT | NS_BUF_CHANGED);

			/* Fill the slot in the NIC ring. */
			/* Use legacy descriptor, they are faster? */
			curr->read.buffer_addr = htole64(paddr);
			curr->read.olinfo_status = 0;
			curr->read.cmd_type_len = htole32(len | flags |
				IXGBE_ADVTXD_DCMD_IFCS | IXGBE_TXD_CMD_EOP);

			/* make sure changes to the buffer are synced */
			bus_dmamap_sync(txr->txtag, txbuf->map,
				BUS_DMASYNC_PREWRITE);

			nm_i = nm_next(nm_i, lim);
			nic_i = nm_next(nic_i, lim);
		}
		kring->nr_hwcur = head;

		/* synchronize the NIC ring */
		bus_dmamap_sync(txr->txdma.dma_tag, txr->txdma.dma_map,
			BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);

		/* (re)start the tx unit up to slot nic_i (excluded) */
		IXGBE_WRITE_REG(&sc->hw, txr->tail, nic_i);
	}

	/*
	 * Second part: reclaim buffers for completed transmissions.
	 * Because this is expensive (we read a NIC register etc.)
	 * we only do it in specific cases (see below).
	 */
	if (flags & NAF_FORCE_RECLAIM) {
		reclaim_tx = 1; /* forced reclaim */
	} else if (!nm_kr_txempty(kring)) {
		reclaim_tx = 0; /* have buffers, no reclaim */
	} else {
		/*
		 * No buffers available. Locate previous slot with
		 * REPORT_STATUS set.
		 * If the slot has DD set, we can reclaim space,
		 * otherwise wait for the next interrupt.
		 * This enables interrupt moderation on the tx
		 * side though it might reduce throughput.
		 */
		struct ixgbe_legacy_tx_desc *txd =
		    (struct ixgbe_legacy_tx_desc *)txr->tx_base;

		nic_i = txr->next_to_clean + report_frequency;
		if (nic_i > lim)
			nic_i -= lim + 1;
		// round to the closest with dd set
		nic_i = (nic_i < kring->nkr_num_slots / 4 ||
			 nic_i >= kring->nkr_num_slots*3/4) ?
			0 : report_frequency;
		reclaim_tx = txd[nic_i].upper.fields.status & IXGBE_TXD_STAT_DD;	// XXX cpu_to_le32 ?
	}
	if (reclaim_tx) {
		/*
		 * Record completed transmissions.
		 * We (re)use the driver's txr->next_to_clean to keep
		 * track of the most recently completed transmission.
		 *
		 * The datasheet discourages the use of TDH to find
		 * out the number of sent packets, but we only set
		 * REPORT_STATUS in a few slots so TDH is the only
		 * good way.
		 */
		nic_i = IXGBE_READ_REG(&sc->hw, IXGBE_TDH(kring->ring_id));
		if (nic_i >= kring->nkr_num_slots) { /* XXX can it happen ? */
#ifdef D
			D("TDH wrap %d", nic_i);
#endif
			nic_i -= kring->nkr_num_slots;
		}
		if (nic_i != txr->next_to_clean) {
			/* some tx completed, increment avail */
			txr->next_to_clean = nic_i;
			kring->nr_hwtail = nm_prev(netmap_idx_n2k(kring, nic_i), lim);
		}
	}

	return 0;
}


/*
 * Reconcile kernel and user view of the receive ring.
 * Same as for the txsync, this routine must be efficient.
 * The caller guarantees a single invocations, but races against
 * the rest of the driver should be handled here.
 *
 * On call, kring->rhead is the first packet that userspace wants
 * to keep, and kring->rcur is the wakeup point.
 * The kernel has previously reported packets up to kring->rtail.
 *
 * If (flags & NAF_FORCE_READ) also check for incoming packets irrespective
 * of whether or not we received an interrupt.
 */
static int
ixgbe_netmap_rxsync(struct netmap_kring *kring, int flags)
{
	struct netmap_adapter *na = kring->na;
	struct ifnet *ifp = na->ifp;
	struct netmap_ring *ring = kring->ring;
	u_int nm_i;	/* index into the netmap ring */
	u_int nic_i;	/* index into the NIC ring */
	u_int n;
	u_int const lim = kring->nkr_num_slots - 1;
	u_int const head = kring->rhead;
	int force_update = (flags & NAF_FORCE_READ) || kring->nr_kflags & NKR_PENDINTR;

	/* device-specific */
	struct ixgbe_softc *sc = ifp->if_softc;
	struct rx_ring *rxr = &sc->rx_rings[kring->ring_id];

	if (head > lim)
		return netmap_ring_reinit(kring);

	/* XXX check sync modes */
	bus_dmamap_sync(rxr->rxdma.dma_tag, rxr->rxdma.dma_map,
			BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);

	/*
	 * First part: import newly received packets.
	 *
	 * nm_i is the index of the next free slot in the netmap ring,
	 * nic_i is the index of the next received packet in the NIC ring,
	 * and they may differ in case if_init() has been called while
	 * in netmap mode. For the receive ring we have
	 *
	 *	nic_i = rxr->next_to_check;
	 *	nm_i = kring->nr_hwtail (previous)
	 * and
	 *	nm_i == (nic_i + kring->nkr_hwofs) % ring_size
	 *
	 * rxr->next_to_check is set to 0 on a ring reinit
	 */
	if (netmap_no_pendintr || force_update) {
		int crclen = (ix_crcstrip) ? 0 : 4;

		nic_i = rxr->next_to_check; // or also k2n(kring->nr_hwtail)
		nm_i = netmap_idx_n2k(kring, nic_i);

		for (n = 0; ; n++) {
			union ixgbe_adv_rx_desc *curr = &rxr->rx_base[nic_i];
			uint32_t staterr = le32toh(curr->wb.upper.status_error);

			if ((staterr & IXGBE_RXD_STAT_DD) == 0)
				break;
			ring->slot[nm_i].len = le16toh(curr->wb.upper.length) - crclen;
			ring->slot[nm_i].flags = 0;
			bus_dmamap_sync(rxr->ptag,
			    rxr->rx_buffers[nic_i].pmap, BUS_DMASYNC_POSTREAD);
			nm_i = nm_next(nm_i, lim);
			nic_i = nm_next(nic_i, lim);
		}
		if (n) { /* update the state variables */
			if (netmap_no_pendintr && !force_update) {
				/* diagnostics */
				ix_rx_miss ++;
				ix_rx_miss_bufs += n;
			}
			rxr->next_to_check = nic_i;
			kring->nr_hwtail = nm_i;
		}
		kring->nr_kflags &= ~NKR_PENDINTR;
	}

	/*
	 * Second part: skip past packets that userspace has released.
	 * (kring->nr_hwcur to kring->rhead excluded),
	 * and make the buffers available for reception.
	 * As usual nm_i is the index in the netmap ring,
	 * nic_i is the index in the NIC ring, and
	 * nm_i == (nic_i + kring->nkr_hwofs) % ring_size
	 */
	nm_i = kring->nr_hwcur;
	if (nm_i != head) {
		nic_i = netmap_idx_k2n(kring, nm_i);
		for (n = 0; nm_i != head; n++) {
			struct netmap_slot *slot = &ring->slot[nm_i];
			uint64_t paddr;
			void *addr = PNMB(na, slot, &paddr);

			union ixgbe_adv_rx_desc *curr = &rxr->rx_base[nic_i];
			struct ixgbe_rx_buf *rxbuf = &rxr->rx_buffers[nic_i];

			if (addr == NETMAP_BUF_BASE(na)) /* bad buf */
				goto ring_reset;

			if (slot->flags & NS_BUF_CHANGED) {
				/* buffer has changed, reload map */
				netmap_reload_map(na, rxr->ptag, rxbuf->pmap, addr);
				slot->flags &= ~NS_BUF_CHANGED;
			}
			curr->wb.upper.status_error = 0;
			curr->read.pkt_addr = htole64(paddr);
			bus_dmamap_sync(rxr->ptag, rxbuf->pmap,
			    BUS_DMASYNC_PREREAD);
			nm_i = nm_next(nm_i, lim);
			nic_i = nm_next(nic_i, lim);
		}
		kring->nr_hwcur = head;

		bus_dmamap_sync(rxr->rxdma.dma_tag, rxr->rxdma.dma_map,
		    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
		/*
		 * IMPORTANT: we must leave one free slot in the ring,
		 * so move nic_i back by one unit
		 */
		nic_i = nm_prev(nic_i, lim);
		IXGBE_WRITE_REG(&sc->hw, rxr->tail, nic_i);
	}

	return 0;

ring_reset:
	return netmap_ring_reinit(kring);
}


/*
 * The attach routine, called near the end of ixgbe_attach(),
 * fills the parameters for netmap_attach() and calls it.
 * It cannot fail, in the worst case (such as no memory)
 * netmap mode will be disabled and the driver will only
 * operate in standard mode.
 */
void
ixgbe_netmap_attach(struct ixgbe_softc *sc)
{
	struct netmap_adapter na;

	bzero(&na, sizeof(na));

	na.ifp = sc->ifp;
	na.na_flags = NAF_BDG_MAYSLEEP;
	na.num_tx_desc = sc->num_tx_desc;
	na.num_rx_desc = sc->num_rx_desc;
	na.nm_txsync = ixgbe_netmap_txsync;
	na.nm_rxsync = ixgbe_netmap_rxsync;
	na.nm_register = ixgbe_netmap_reg;
	na.num_tx_rings = na.num_rx_rings = sc->num_queues;
	netmap_attach(&na);
}

#endif /* DEV_NETMAP */

/* end of file */