[linux-block.git] / drivers / net / xen-netback / rx.c

/*
 * Copyright (c) 2016 Citrix Systems Inc.
 * Copyright (c) 2002-2005, K A Fraser
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */
#include "common.h"

#include <linux/kthread.h>

#include <xen/xen.h>
#include <xen/events.h>

/*
 * Update the needed ring page slots for the first SKB queued.
 * Note that any call sequence outside the RX thread calling this function
 * needs to wake up the RX thread via a call of xenvif_kick_thread()
 * afterwards in order to avoid a race with putting the thread to sleep.
 */
static void xenvif_update_needed_slots(struct xenvif_queue *queue,
				       const struct sk_buff *skb)
{
	unsigned int needed = 0;

	if (skb) {
		needed = DIV_ROUND_UP(skb->len, XEN_PAGE_SIZE);
		if (skb_is_gso(skb))
			needed++;
		if (skb->sw_hash)
			needed++;
	}

	WRITE_ONCE(queue->rx_slots_needed, needed);
}

static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue)
{
	RING_IDX prod, cons;
	unsigned int needed;

	needed = READ_ONCE(queue->rx_slots_needed);
	if (!needed)
		return false;

	do {
		prod = queue->rx.sring->req_prod;
		cons = queue->rx.req_cons;

		if (prod - cons >= needed)
			return true;

		queue->rx.sring->req_event = prod + 1;

		/* Make sure event is visible before we check prod
		 * again.
		 */
		mb();
	} while (queue->rx.sring->req_prod != prod);

	return false;
}

bool xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb)
{
	unsigned long flags;
	bool ret = true;

	spin_lock_irqsave(&queue->rx_queue.lock, flags);

	if (queue->rx_queue_len >= queue->rx_queue_max) {
		struct net_device *dev = queue->vif->dev;

		netif_tx_stop_queue(netdev_get_tx_queue(dev, queue->id));
		ret = false;
	} else {
		if (skb_queue_empty(&queue->rx_queue))
			xenvif_update_needed_slots(queue, skb);

		__skb_queue_tail(&queue->rx_queue, skb);

		queue->rx_queue_len += skb->len;
	}

	spin_unlock_irqrestore(&queue->rx_queue.lock, flags);

	return ret;
}

static struct sk_buff *xenvif_rx_dequeue(struct xenvif_queue *queue)
{
	struct sk_buff *skb;

	spin_lock_irq(&queue->rx_queue.lock);

	skb = __skb_dequeue(&queue->rx_queue);
	if (skb) {
		xenvif_update_needed_slots(queue, skb_peek(&queue->rx_queue));

		queue->rx_queue_len -= skb->len;
		if (queue->rx_queue_len < queue->rx_queue_max) {
			struct netdev_queue *txq;

			txq = netdev_get_tx_queue(queue->vif->dev, queue->id);
			netif_tx_wake_queue(txq);
		}
	}

	spin_unlock_irq(&queue->rx_queue.lock);

	return skb;
}

static void xenvif_rx_queue_purge(struct xenvif_queue *queue)
{
	struct sk_buff *skb;

	while ((skb = xenvif_rx_dequeue(queue)) != NULL)
		kfree_skb(skb);
}

static void xenvif_rx_queue_drop_expired(struct xenvif_queue *queue)
{
	struct sk_buff *skb;

	for (;;) {
		skb = skb_peek(&queue->rx_queue);
		if (!skb)
			break;
		if (time_before(jiffies, XENVIF_RX_CB(skb)->expires))
			break;
		xenvif_rx_dequeue(queue);
		kfree_skb(skb);
		queue->vif->dev->stats.rx_dropped++;
	}
}

static void xenvif_rx_copy_flush(struct xenvif_queue *queue)
{
	unsigned int i;
	int notify;

	gnttab_batch_copy(queue->rx_copy.op, queue->rx_copy.num);

	for (i = 0; i < queue->rx_copy.num; i++) {
		struct gnttab_copy *op;

		op = &queue->rx_copy.op[i];

		/* If the copy failed, overwrite the status field in
		 * the corresponding response.
		 */
		if (unlikely(op->status != GNTST_okay)) {
			struct xen_netif_rx_response *rsp;

			rsp = RING_GET_RESPONSE(&queue->rx,
						queue->rx_copy.idx[i]);
			rsp->status = op->status;
		}
	}

	queue->rx_copy.num = 0;

	/* Push responses for all completed packets. */
	RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->rx, notify);
	if (notify)
		notify_remote_via_irq(queue->rx_irq);

	__skb_queue_purge(queue->rx_copy.completed);
}

static void xenvif_rx_copy_add(struct xenvif_queue *queue,
			       struct xen_netif_rx_request *req,
			       unsigned int offset, void *data, size_t len)
{
	struct gnttab_copy *op;
	struct page *page;
	struct xen_page_foreign *foreign;

	if (queue->rx_copy.num == COPY_BATCH_SIZE)
		xenvif_rx_copy_flush(queue);

	op = &queue->rx_copy.op[queue->rx_copy.num];

	page = virt_to_page(data);

	op->flags = GNTCOPY_dest_gref;

	foreign = xen_page_foreign(page);
	if (foreign) {
		op->source.domid = foreign->domid;
		op->source.u.ref = foreign->gref;
		op->flags |= GNTCOPY_source_gref;
	} else {
		op->source.u.gmfn = virt_to_gfn(data);
		op->source.domid  = DOMID_SELF;
	}

	op->source.offset = xen_offset_in_page(data);
	op->dest.u.ref    = req->gref;
	op->dest.domid    = queue->vif->domid;
	op->dest.offset   = offset;
	op->len           = len;

	queue->rx_copy.idx[queue->rx_copy.num] = queue->rx.req_cons;
	queue->rx_copy.num++;
}

static unsigned int xenvif_gso_type(struct sk_buff *skb)
{
	if (skb_is_gso(skb)) {
		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
			return XEN_NETIF_GSO_TYPE_TCPV4;
		else
			return XEN_NETIF_GSO_TYPE_TCPV6;
	}
	return XEN_NETIF_GSO_TYPE_NONE;
}

struct xenvif_pkt_state {
	struct sk_buff *skb;
	size_t remaining_len;
	struct sk_buff *frag_iter;
	int frag; /* frag == -1 => frag_iter->head */
	unsigned int frag_offset;
	struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX - 1];
	unsigned int extra_count;
	unsigned int slot;
};

static void xenvif_rx_next_skb(struct xenvif_queue *queue,
			       struct xenvif_pkt_state *pkt)
{
	struct sk_buff *skb;
	unsigned int gso_type;

	skb = xenvif_rx_dequeue(queue);

	queue->stats.tx_bytes += skb->len;
	queue->stats.tx_packets++;

	/* Reset packet state. */
	memset(pkt, 0, sizeof(struct xenvif_pkt_state));

	pkt->skb = skb;
	pkt->frag_iter = skb;
	pkt->remaining_len = skb->len;
	pkt->frag = -1;

	gso_type = xenvif_gso_type(skb);
	if ((1 << gso_type) & queue->vif->gso_mask) {
		struct xen_netif_extra_info *extra;

		extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];

		extra->u.gso.type = gso_type;
		extra->u.gso.size = skb_shinfo(skb)->gso_size;
		extra->u.gso.pad = 0;
		extra->u.gso.features = 0;
		extra->type = XEN_NETIF_EXTRA_TYPE_GSO;
		extra->flags = 0;

		pkt->extra_count++;
	}

	if (queue->vif->xdp_headroom) {
		struct xen_netif_extra_info *extra;

		extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_XDP - 1];

		memset(extra, 0, sizeof(struct xen_netif_extra_info));
		extra->u.xdp.headroom = queue->vif->xdp_headroom;
		extra->type = XEN_NETIF_EXTRA_TYPE_XDP;
		extra->flags = 0;

		pkt->extra_count++;
	}

	if (skb->sw_hash) {
		struct xen_netif_extra_info *extra;

		extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_HASH - 1];

		extra->u.hash.algorithm =
			XEN_NETIF_CTRL_HASH_ALGORITHM_TOEPLITZ;

		if (skb->l4_hash)
			extra->u.hash.type =
				skb->protocol == htons(ETH_P_IP) ?
				_XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP :
				_XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP;
		else
			extra->u.hash.type =
				skb->protocol == htons(ETH_P_IP) ?
				_XEN_NETIF_CTRL_HASH_TYPE_IPV4 :
				_XEN_NETIF_CTRL_HASH_TYPE_IPV6;

		*(uint32_t *)extra->u.hash.value = skb_get_hash_raw(skb);

		extra->type = XEN_NETIF_EXTRA_TYPE_HASH;
		extra->flags = 0;

		pkt->extra_count++;
	}
}

static void xenvif_rx_complete(struct xenvif_queue *queue,
			       struct xenvif_pkt_state *pkt)
{
	/* All responses are ready to be pushed. */
	queue->rx.rsp_prod_pvt = queue->rx.req_cons;

	__skb_queue_tail(queue->rx_copy.completed, pkt->skb);
}

static void xenvif_rx_next_frag(struct xenvif_pkt_state *pkt)
{
	struct sk_buff *frag_iter = pkt->frag_iter;
	unsigned int nr_frags = skb_shinfo(frag_iter)->nr_frags;

	pkt->frag++;
	pkt->frag_offset = 0;

	if (pkt->frag >= nr_frags) {
		if (frag_iter == pkt->skb)
			pkt->frag_iter = skb_shinfo(frag_iter)->frag_list;
		else
			pkt->frag_iter = frag_iter->next;

		pkt->frag = -1;
	}
}

static void xenvif_rx_next_chunk(struct xenvif_queue *queue,
				 struct xenvif_pkt_state *pkt,
				 unsigned int offset, void **data,
				 size_t *len)
{
	struct sk_buff *frag_iter = pkt->frag_iter;
	void *frag_data;
	size_t frag_len, chunk_len;

	BUG_ON(!frag_iter);

	if (pkt->frag == -1) {
		frag_data = frag_iter->data;
		frag_len = skb_headlen(frag_iter);
	} else {
		skb_frag_t *frag = &skb_shinfo(frag_iter)->frags[pkt->frag];

		frag_data = skb_frag_address(frag);
		frag_len = skb_frag_size(frag);
	}

	frag_data += pkt->frag_offset;
	frag_len -= pkt->frag_offset;

	chunk_len = min_t(size_t, frag_len, XEN_PAGE_SIZE - offset);
	chunk_len = min_t(size_t, chunk_len, XEN_PAGE_SIZE -
					     xen_offset_in_page(frag_data));

	pkt->frag_offset += chunk_len;

	/* Advance to next frag? */
	if (frag_len == chunk_len)
		xenvif_rx_next_frag(pkt);

	*data = frag_data;
	*len = chunk_len;
}

static void xenvif_rx_data_slot(struct xenvif_queue *queue,
				struct xenvif_pkt_state *pkt,
				struct xen_netif_rx_request *req,
				struct xen_netif_rx_response *rsp)
{
	unsigned int offset = queue->vif->xdp_headroom;
	unsigned int flags;

	do {
		size_t len;
		void *data;

		xenvif_rx_next_chunk(queue, pkt, offset, &data, &len);
		xenvif_rx_copy_add(queue, req, offset, data, len);

		offset += len;
		pkt->remaining_len -= len;

	} while (offset < XEN_PAGE_SIZE && pkt->remaining_len > 0);

	if (pkt->remaining_len > 0)
		flags = XEN_NETRXF_more_data;
	else
		flags = 0;

	if (pkt->slot == 0) {
		struct sk_buff *skb = pkt->skb;

		if (skb->ip_summed == CHECKSUM_PARTIAL)
			flags |= XEN_NETRXF_csum_blank |
				 XEN_NETRXF_data_validated;
		else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
			flags |= XEN_NETRXF_data_validated;

		if (pkt->extra_count != 0)
			flags |= XEN_NETRXF_extra_info;
	}

	rsp->offset = 0;
	rsp->flags = flags;
	rsp->id = req->id;
	rsp->status = (s16)offset;
}

static void xenvif_rx_extra_slot(struct xenvif_queue *queue,
				 struct xenvif_pkt_state *pkt,
				 struct xen_netif_rx_request *req,
				 struct xen_netif_rx_response *rsp)
{
	struct xen_netif_extra_info *extra = (void *)rsp;
	unsigned int i;

	pkt->extra_count--;

	for (i = 0; i < ARRAY_SIZE(pkt->extras); i++) {
		if (pkt->extras[i].type) {
			*extra = pkt->extras[i];

			if (pkt->extra_count != 0)
				extra->flags |= XEN_NETIF_EXTRA_FLAG_MORE;

			pkt->extras[i].type = 0;
			return;
		}
	}
	BUG();
}

static void xenvif_rx_skb(struct xenvif_queue *queue)
{
	struct xenvif_pkt_state pkt;

	xenvif_rx_next_skb(queue, &pkt);

	queue->last_rx_time = jiffies;

	do {
		struct xen_netif_rx_request *req;
		struct xen_netif_rx_response *rsp;

		req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons);
		rsp = RING_GET_RESPONSE(&queue->rx, queue->rx.req_cons);

		/* Extras must go after the first data slot */
		if (pkt.slot != 0 && pkt.extra_count != 0)
			xenvif_rx_extra_slot(queue, &pkt, req, rsp);
		else
			xenvif_rx_data_slot(queue, &pkt, req, rsp);

		queue->rx.req_cons++;
		pkt.slot++;
	} while (pkt.remaining_len > 0 || pkt.extra_count != 0);

	xenvif_rx_complete(queue, &pkt);
}

#define RX_BATCH_SIZE 64

static void xenvif_rx_action(struct xenvif_queue *queue)
{
	struct sk_buff_head completed_skbs;
	unsigned int work_done = 0;

	__skb_queue_head_init(&completed_skbs);
	queue->rx_copy.completed = &completed_skbs;

	while (xenvif_rx_ring_slots_available(queue) &&
	       !skb_queue_empty(&queue->rx_queue) &&
	       work_done < RX_BATCH_SIZE) {
		xenvif_rx_skb(queue);
		work_done++;
	}

	/* Flush any pending copies and complete all skbs. */
	xenvif_rx_copy_flush(queue);
}

static RING_IDX xenvif_rx_queue_slots(const struct xenvif_queue *queue)
{
	RING_IDX prod, cons;

	prod = queue->rx.sring->req_prod;
	cons = queue->rx.req_cons;

	return prod - cons;
}

static bool xenvif_rx_queue_stalled(const struct xenvif_queue *queue)
{
	unsigned int needed = READ_ONCE(queue->rx_slots_needed);

	return !queue->stalled &&
		xenvif_rx_queue_slots(queue) < needed &&
		time_after(jiffies,
			   queue->last_rx_time + queue->vif->stall_timeout);
}

static bool xenvif_rx_queue_ready(struct xenvif_queue *queue)
{
	unsigned int needed = READ_ONCE(queue->rx_slots_needed);

	return queue->stalled && xenvif_rx_queue_slots(queue) >= needed;
}

bool xenvif_have_rx_work(struct xenvif_queue *queue, bool test_kthread)
{
	return xenvif_rx_ring_slots_available(queue) ||
		(queue->vif->stall_timeout &&
		 (xenvif_rx_queue_stalled(queue) ||
		  xenvif_rx_queue_ready(queue))) ||
		(test_kthread && kthread_should_stop()) ||
		queue->vif->disabled;
}

static long xenvif_rx_queue_timeout(struct xenvif_queue *queue)
{
	struct sk_buff *skb;
	long timeout;

	skb = skb_peek(&queue->rx_queue);
	if (!skb)
		return MAX_SCHEDULE_TIMEOUT;

	timeout = XENVIF_RX_CB(skb)->expires - jiffies;
	return timeout < 0 ? 0 : timeout;
}

/* Wait until the guest Rx thread has work.
 *
 * The timeout needs to be adjusted based on the current head of the
 * queue (and not just the head at the beginning).  In particular, if
 * the queue is initially empty an infinite timeout is used and this
 * needs to be reduced when a skb is queued.
 *
 * This cannot be done with wait_event_timeout() because it only
 * calculates the timeout once.
 */
static void xenvif_wait_for_rx_work(struct xenvif_queue *queue)
{
	DEFINE_WAIT(wait);

	if (xenvif_have_rx_work(queue, true))
		return;

	for (;;) {
		long ret;

		prepare_to_wait(&queue->wq, &wait, TASK_INTERRUPTIBLE);
		if (xenvif_have_rx_work(queue, true))
			break;
		if (atomic_fetch_andnot(NETBK_RX_EOI | NETBK_COMMON_EOI,
					&queue->eoi_pending) &
		    (NETBK_RX_EOI | NETBK_COMMON_EOI))
			xen_irq_lateeoi(queue->rx_irq, 0);

		ret = schedule_timeout(xenvif_rx_queue_timeout(queue));
		if (!ret)
			break;
	}
	finish_wait(&queue->wq, &wait);
}

static void xenvif_queue_carrier_off(struct xenvif_queue *queue)
{
	struct xenvif *vif = queue->vif;

	queue->stalled = true;

	/* At least one queue has stalled? Disable the carrier. */
	spin_lock(&vif->lock);
	if (vif->stalled_queues++ == 0) {
		netdev_info(vif->dev, "Guest Rx stalled");
		netif_carrier_off(vif->dev);
	}
	spin_unlock(&vif->lock);
}

static void xenvif_queue_carrier_on(struct xenvif_queue *queue)
{
	struct xenvif *vif = queue->vif;

	queue->last_rx_time = jiffies; /* Reset Rx stall detection. */
	queue->stalled = false;

	/* All queues are ready? Enable the carrier. */
	spin_lock(&vif->lock);
	if (--vif->stalled_queues == 0) {
		netdev_info(vif->dev, "Guest Rx ready");
		netif_carrier_on(vif->dev);
	}
	spin_unlock(&vif->lock);
}

int xenvif_kthread_guest_rx(void *data)
{
	struct xenvif_queue *queue = data;
	struct xenvif *vif = queue->vif;

	if (!vif->stall_timeout)
		xenvif_queue_carrier_on(queue);

	for (;;) {
		xenvif_wait_for_rx_work(queue);

		if (kthread_should_stop())
			break;

		/* This frontend is found to be rogue, disable it in
		 * kthread context. Currently this is only set when
		 * netback finds out frontend sends malformed packet,
		 * but we cannot disable the interface in softirq
		 * context so we defer it here, if this thread is
		 * associated with queue 0.
		 */
		if (unlikely(vif->disabled && queue->id == 0)) {
			xenvif_carrier_off(vif);
			break;
		}

		if (!skb_queue_empty(&queue->rx_queue))
			xenvif_rx_action(queue);

		/* If the guest hasn't provided any Rx slots for a
		 * while it's probably not responsive, drop the
		 * carrier so packets are dropped earlier.
		 */
		if (vif->stall_timeout) {
			if (xenvif_rx_queue_stalled(queue))
				xenvif_queue_carrier_off(queue);
			else if (xenvif_rx_queue_ready(queue))
				xenvif_queue_carrier_on(queue);
		}

		/* Queued packets may have foreign pages from other
		 * domains.  These cannot be queued indefinitely as
		 * this would starve guests of grant refs and transmit
		 * slots.
		 */
		xenvif_rx_queue_drop_expired(queue);

		cond_resched();
	}

	/* Bin any remaining skbs */
	xenvif_rx_queue_purge(queue);

	return 0;
}
Commit	Line	Data
	1	/*
	2	* Copyright (c) 2016 Citrix Systems Inc.
	3	* Copyright (c) 2002-2005, K A Fraser
	4	*
	5	* This program is free software; you can redistribute it and/or
	6	* modify it under the terms of the GNU General Public License version 2
	7	* as published by the Free Software Foundation; or, when distributed
	8	* separately from the Linux kernel or incorporated into other
	9	* software packages, subject to the following license:
	10	*
	11	* Permission is hereby granted, free of charge, to any person obtaining a copy
	12	* of this source file (the "Software"), to deal in the Software without
	13	* restriction, including without limitation the rights to use, copy, modify,
	14	* merge, publish, distribute, sublicense, and/or sell copies of the Software,
	15	* and to permit persons to whom the Software is furnished to do so, subject to
	16	* the following conditions:
	17	*
	18	* The above copyright notice and this permission notice shall be included in
	19	* all copies or substantial portions of the Software.
	20	*
	21	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	22	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	23	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	24	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	25	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	26	* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
	27	* IN THE SOFTWARE.
	28	*/
	29	#include "common.h"
	30
	31	#include <linux/kthread.h>
	32
	33	#include <xen/xen.h>
	34	#include <xen/events.h>
	35
	36	/*
	37	* Update the needed ring page slots for the first SKB queued.
	38	* Note that any call sequence outside the RX thread calling this function
	39	* needs to wake up the RX thread via a call of xenvif_kick_thread()
	40	* afterwards in order to avoid a race with putting the thread to sleep.
	41	*/
	42	static void xenvif_update_needed_slots(struct xenvif_queue *queue,
	43	const struct sk_buff *skb)
	44	{
	45	unsigned int needed = 0;
	46
	47	if (skb) {
	48	needed = DIV_ROUND_UP(skb->len, XEN_PAGE_SIZE);
	49	if (skb_is_gso(skb))
	50	needed++;
	51	if (skb->sw_hash)
	52	needed++;
	53	}
	54
	55	WRITE_ONCE(queue->rx_slots_needed, needed);
	56	}
	57
	58	static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue)
	59	{
	60	RING_IDX prod, cons;
	61	unsigned int needed;
	62
	63	needed = READ_ONCE(queue->rx_slots_needed);
	64	if (!needed)
	65	return false;
	66
	67	do {
	68	prod = queue->rx.sring->req_prod;
	69	cons = queue->rx.req_cons;
	70
	71	if (prod - cons >= needed)
	72	return true;
	73
	74	queue->rx.sring->req_event = prod + 1;
	75
	76	/* Make sure event is visible before we check prod
	77	* again.
	78	*/
	79	mb();
	80	} while (queue->rx.sring->req_prod != prod);
	81
	82	return false;
	83	}
	84
	85	bool xenvif_rx_queue_tail(struct xenvif_queue queue, struct sk_buff skb)
	86	{
	87	unsigned long flags;
	88	bool ret = true;
	89
	90	spin_lock_irqsave(&queue->rx_queue.lock, flags);
	91
	92	if (queue->rx_queue_len >= queue->rx_queue_max) {
	93	struct net_device *dev = queue->vif->dev;
	94
	95	netif_tx_stop_queue(netdev_get_tx_queue(dev, queue->id));
	96	ret = false;
	97	} else {
	98	if (skb_queue_empty(&queue->rx_queue))
	99	xenvif_update_needed_slots(queue, skb);
	100
	101	__skb_queue_tail(&queue->rx_queue, skb);
	102
	103	queue->rx_queue_len += skb->len;
	104	}
	105
	106	spin_unlock_irqrestore(&queue->rx_queue.lock, flags);
	107
	108	return ret;
	109	}
	110
	111	static struct sk_buff xenvif_rx_dequeue(struct xenvif_queue queue)
	112	{
	113	struct sk_buff *skb;
	114
	115	spin_lock_irq(&queue->rx_queue.lock);
	116
	117	skb = __skb_dequeue(&queue->rx_queue);
	118	if (skb) {
	119	xenvif_update_needed_slots(queue, skb_peek(&queue->rx_queue));
	120
	121	queue->rx_queue_len -= skb->len;
	122	if (queue->rx_queue_len < queue->rx_queue_max) {
	123	struct netdev_queue *txq;
	124
	125	txq = netdev_get_tx_queue(queue->vif->dev, queue->id);
	126	netif_tx_wake_queue(txq);
	127	}
	128	}
	129
	130	spin_unlock_irq(&queue->rx_queue.lock);
	131
	132	return skb;
	133	}
	134
	135	static void xenvif_rx_queue_purge(struct xenvif_queue *queue)
	136	{
	137	struct sk_buff *skb;
	138
	139	while ((skb = xenvif_rx_dequeue(queue)) != NULL)
	140	kfree_skb(skb);
	141	}
	142
	143	static void xenvif_rx_queue_drop_expired(struct xenvif_queue *queue)
	144	{
	145	struct sk_buff *skb;
	146
	147	for (;;) {
	148	skb = skb_peek(&queue->rx_queue);
	149	if (!skb)
	150	break;
	151	if (time_before(jiffies, XENVIF_RX_CB(skb)->expires))
	152	break;
	153	xenvif_rx_dequeue(queue);
	154	kfree_skb(skb);
	155	queue->vif->dev->stats.rx_dropped++;
	156	}
	157	}
	158
	159	static void xenvif_rx_copy_flush(struct xenvif_queue *queue)
	160	{
	161	unsigned int i;
	162	int notify;
	163
	164	gnttab_batch_copy(queue->rx_copy.op, queue->rx_copy.num);
	165
	166	for (i = 0; i < queue->rx_copy.num; i++) {
	167	struct gnttab_copy *op;
	168
	169	op = &queue->rx_copy.op[i];
	170
	171	/* If the copy failed, overwrite the status field in
	172	* the corresponding response.
	173	*/
	174	if (unlikely(op->status != GNTST_okay)) {
	175	struct xen_netif_rx_response *rsp;
	176
	177	rsp = RING_GET_RESPONSE(&queue->rx,
	178	queue->rx_copy.idx[i]);
	179	rsp->status = op->status;
	180	}
	181	}
	182
	183	queue->rx_copy.num = 0;
	184
	185	/* Push responses for all completed packets. */
	186	RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->rx, notify);
	187	if (notify)
	188	notify_remote_via_irq(queue->rx_irq);
	189
	190	__skb_queue_purge(queue->rx_copy.completed);
	191	}
	192
	193	static void xenvif_rx_copy_add(struct xenvif_queue *queue,
	194	struct xen_netif_rx_request *req,
	195	unsigned int offset, void *data, size_t len)
	196	{
	197	struct gnttab_copy *op;
	198	struct page *page;
	199	struct xen_page_foreign *foreign;
	200
	201	if (queue->rx_copy.num == COPY_BATCH_SIZE)
	202	xenvif_rx_copy_flush(queue);
	203
	204	op = &queue->rx_copy.op[queue->rx_copy.num];
	205
	206	page = virt_to_page(data);
	207
	208	op->flags = GNTCOPY_dest_gref;
	209
	210	foreign = xen_page_foreign(page);
	211	if (foreign) {
	212	op->source.domid = foreign->domid;
	213	op->source.u.ref = foreign->gref;
	214	op->flags \|= GNTCOPY_source_gref;
	215	} else {
	216	op->source.u.gmfn = virt_to_gfn(data);
	217	op->source.domid = DOMID_SELF;
	218	}
	219
	220	op->source.offset = xen_offset_in_page(data);
	221	op->dest.u.ref = req->gref;
	222	op->dest.domid = queue->vif->domid;
	223	op->dest.offset = offset;
	224	op->len = len;
	225
	226	queue->rx_copy.idx[queue->rx_copy.num] = queue->rx.req_cons;
	227	queue->rx_copy.num++;
	228	}
	229
	230	static unsigned int xenvif_gso_type(struct sk_buff *skb)
	231	{
	232	if (skb_is_gso(skb)) {
	233	if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
	234	return XEN_NETIF_GSO_TYPE_TCPV4;
	235	else
	236	return XEN_NETIF_GSO_TYPE_TCPV6;
	237	}
	238	return XEN_NETIF_GSO_TYPE_NONE;
	239	}
	240
	241	struct xenvif_pkt_state {
	242	struct sk_buff *skb;
	243	size_t remaining_len;
	244	struct sk_buff *frag_iter;
	245	int frag; /* frag == -1 => frag_iter->head */
	246	unsigned int frag_offset;
	247	struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX - 1];
	248	unsigned int extra_count;
	249	unsigned int slot;
	250	};
	251
	252	static void xenvif_rx_next_skb(struct xenvif_queue *queue,
	253	struct xenvif_pkt_state *pkt)
	254	{
	255	struct sk_buff *skb;
	256	unsigned int gso_type;
	257
	258	skb = xenvif_rx_dequeue(queue);
	259
	260	queue->stats.tx_bytes += skb->len;
	261	queue->stats.tx_packets++;
	262
	263	/* Reset packet state. */
	264	memset(pkt, 0, sizeof(struct xenvif_pkt_state));
	265
	266	pkt->skb = skb;
	267	pkt->frag_iter = skb;
	268	pkt->remaining_len = skb->len;
	269	pkt->frag = -1;
	270
	271	gso_type = xenvif_gso_type(skb);
	272	if ((1 << gso_type) & queue->vif->gso_mask) {
	273	struct xen_netif_extra_info *extra;
	274
	275	extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
	276
	277	extra->u.gso.type = gso_type;
	278	extra->u.gso.size = skb_shinfo(skb)->gso_size;
	279	extra->u.gso.pad = 0;
	280	extra->u.gso.features = 0;
	281	extra->type = XEN_NETIF_EXTRA_TYPE_GSO;
	282	extra->flags = 0;
	283
	284	pkt->extra_count++;
	285	}
	286
	287	if (queue->vif->xdp_headroom) {
	288	struct xen_netif_extra_info *extra;
	289
	290	extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_XDP - 1];
	291
	292	memset(extra, 0, sizeof(struct xen_netif_extra_info));
	293	extra->u.xdp.headroom = queue->vif->xdp_headroom;
	294	extra->type = XEN_NETIF_EXTRA_TYPE_XDP;
	295	extra->flags = 0;
	296
	297	pkt->extra_count++;
	298	}
	299
	300	if (skb->sw_hash) {
	301	struct xen_netif_extra_info *extra;
	302
	303	extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_HASH - 1];
	304
	305	extra->u.hash.algorithm =
	306	XEN_NETIF_CTRL_HASH_ALGORITHM_TOEPLITZ;
	307
	308	if (skb->l4_hash)
	309	extra->u.hash.type =
	310	skb->protocol == htons(ETH_P_IP) ?
	311	_XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP :
	312	_XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP;
	313	else
	314	extra->u.hash.type =
	315	skb->protocol == htons(ETH_P_IP) ?
	316	_XEN_NETIF_CTRL_HASH_TYPE_IPV4 :
	317	_XEN_NETIF_CTRL_HASH_TYPE_IPV6;
	318
	319	(uint32_t )extra->u.hash.value = skb_get_hash_raw(skb);
	320
	321	extra->type = XEN_NETIF_EXTRA_TYPE_HASH;
	322	extra->flags = 0;
	323
	324	pkt->extra_count++;
	325	}
	326	}
	327
	328	static void xenvif_rx_complete(struct xenvif_queue *queue,
	329	struct xenvif_pkt_state *pkt)
	330	{
	331	/* All responses are ready to be pushed. */
	332	queue->rx.rsp_prod_pvt = queue->rx.req_cons;
	333
	334	__skb_queue_tail(queue->rx_copy.completed, pkt->skb);
	335	}
	336
	337	static void xenvif_rx_next_frag(struct xenvif_pkt_state *pkt)
	338	{
	339	struct sk_buff *frag_iter = pkt->frag_iter;
	340	unsigned int nr_frags = skb_shinfo(frag_iter)->nr_frags;
	341
	342	pkt->frag++;
	343	pkt->frag_offset = 0;
	344
	345	if (pkt->frag >= nr_frags) {
	346	if (frag_iter == pkt->skb)
	347	pkt->frag_iter = skb_shinfo(frag_iter)->frag_list;
	348	else
	349	pkt->frag_iter = frag_iter->next;
	350
	351	pkt->frag = -1;
	352	}
	353	}
	354
	355	static void xenvif_rx_next_chunk(struct xenvif_queue *queue,
	356	struct xenvif_pkt_state *pkt,
	357	unsigned int offset, void **data,
	358	size_t *len)
	359	{
	360	struct sk_buff *frag_iter = pkt->frag_iter;
	361	void *frag_data;
	362	size_t frag_len, chunk_len;
	363
	364	BUG_ON(!frag_iter);
	365
	366	if (pkt->frag == -1) {
	367	frag_data = frag_iter->data;
	368	frag_len = skb_headlen(frag_iter);
	369	} else {
	370	skb_frag_t *frag = &skb_shinfo(frag_iter)->frags[pkt->frag];
	371
	372	frag_data = skb_frag_address(frag);
	373	frag_len = skb_frag_size(frag);
	374	}
	375
	376	frag_data += pkt->frag_offset;
	377	frag_len -= pkt->frag_offset;
	378
	379	chunk_len = min_t(size_t, frag_len, XEN_PAGE_SIZE - offset);
	380	chunk_len = min_t(size_t, chunk_len, XEN_PAGE_SIZE -
	381	xen_offset_in_page(frag_data));
	382
	383	pkt->frag_offset += chunk_len;
	384
	385	/* Advance to next frag? */
	386	if (frag_len == chunk_len)
	387	xenvif_rx_next_frag(pkt);
	388
	389	*data = frag_data;
	390	*len = chunk_len;
	391	}
	392
	393	static void xenvif_rx_data_slot(struct xenvif_queue *queue,
	394	struct xenvif_pkt_state *pkt,
	395	struct xen_netif_rx_request *req,
	396	struct xen_netif_rx_response *rsp)
	397	{
	398	unsigned int offset = queue->vif->xdp_headroom;
	399	unsigned int flags;
	400
	401	do {
	402	size_t len;
	403	void *data;
	404
	405	xenvif_rx_next_chunk(queue, pkt, offset, &data, &len);
	406	xenvif_rx_copy_add(queue, req, offset, data, len);
	407
	408	offset += len;
	409	pkt->remaining_len -= len;
	410
	411	} while (offset < XEN_PAGE_SIZE && pkt->remaining_len > 0);
	412
	413	if (pkt->remaining_len > 0)
	414	flags = XEN_NETRXF_more_data;
	415	else
	416	flags = 0;
	417
	418	if (pkt->slot == 0) {
	419	struct sk_buff *skb = pkt->skb;
	420
	421	if (skb->ip_summed == CHECKSUM_PARTIAL)
	422	flags \|= XEN_NETRXF_csum_blank \|
	423	XEN_NETRXF_data_validated;
	424	else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
	425	flags \|= XEN_NETRXF_data_validated;
	426
	427	if (pkt->extra_count != 0)
	428	flags \|= XEN_NETRXF_extra_info;
	429	}
	430
	431	rsp->offset = 0;
	432	rsp->flags = flags;
	433	rsp->id = req->id;
	434	rsp->status = (s16)offset;
	435	}
	436
	437	static void xenvif_rx_extra_slot(struct xenvif_queue *queue,
	438	struct xenvif_pkt_state *pkt,
	439	struct xen_netif_rx_request *req,
	440	struct xen_netif_rx_response *rsp)
	441	{
	442	struct xen_netif_extra_info extra = (void )rsp;
	443	unsigned int i;
	444
	445	pkt->extra_count--;
	446
	447	for (i = 0; i < ARRAY_SIZE(pkt->extras); i++) {
	448	if (pkt->extras[i].type) {
	449	*extra = pkt->extras[i];
	450
	451	if (pkt->extra_count != 0)
	452	extra->flags \|= XEN_NETIF_EXTRA_FLAG_MORE;
	453
	454	pkt->extras[i].type = 0;
	455	return;
	456	}
	457	}
	458	BUG();
	459	}
	460
	461	static void xenvif_rx_skb(struct xenvif_queue *queue)
	462	{
	463	struct xenvif_pkt_state pkt;
	464
	465	xenvif_rx_next_skb(queue, &pkt);
	466
	467	queue->last_rx_time = jiffies;
	468
	469	do {
	470	struct xen_netif_rx_request *req;
	471	struct xen_netif_rx_response *rsp;
	472
	473	req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons);
	474	rsp = RING_GET_RESPONSE(&queue->rx, queue->rx.req_cons);
	475
	476	/* Extras must go after the first data slot */
	477	if (pkt.slot != 0 && pkt.extra_count != 0)
	478	xenvif_rx_extra_slot(queue, &pkt, req, rsp);
	479	else
	480	xenvif_rx_data_slot(queue, &pkt, req, rsp);
	481
	482	queue->rx.req_cons++;
	483	pkt.slot++;
	484	} while (pkt.remaining_len > 0 \|\| pkt.extra_count != 0);
	485
	486	xenvif_rx_complete(queue, &pkt);
	487	}
	488
	489	#define RX_BATCH_SIZE 64
	490
	491	static void xenvif_rx_action(struct xenvif_queue *queue)
	492	{
	493	struct sk_buff_head completed_skbs;
	494	unsigned int work_done = 0;
	495
	496	__skb_queue_head_init(&completed_skbs);
	497	queue->rx_copy.completed = &completed_skbs;
	498
	499	while (xenvif_rx_ring_slots_available(queue) &&
	500	!skb_queue_empty(&queue->rx_queue) &&
	501	work_done < RX_BATCH_SIZE) {
	502	xenvif_rx_skb(queue);
	503	work_done++;
	504	}
	505
	506	/* Flush any pending copies and complete all skbs. */
	507	xenvif_rx_copy_flush(queue);
	508	}
	509
	510	static RING_IDX xenvif_rx_queue_slots(const struct xenvif_queue *queue)
	511	{
	512	RING_IDX prod, cons;
	513
	514	prod = queue->rx.sring->req_prod;
	515	cons = queue->rx.req_cons;
	516
	517	return prod - cons;
	518	}
	519
	520	static bool xenvif_rx_queue_stalled(const struct xenvif_queue *queue)
	521	{
	522	unsigned int needed = READ_ONCE(queue->rx_slots_needed);
	523
	524	return !queue->stalled &&
	525	xenvif_rx_queue_slots(queue) < needed &&
	526	time_after(jiffies,
	527	queue->last_rx_time + queue->vif->stall_timeout);
	528	}
	529
	530	static bool xenvif_rx_queue_ready(struct xenvif_queue *queue)
	531	{
	532	unsigned int needed = READ_ONCE(queue->rx_slots_needed);
	533
	534	return queue->stalled && xenvif_rx_queue_slots(queue) >= needed;
	535	}
	536
	537	bool xenvif_have_rx_work(struct xenvif_queue *queue, bool test_kthread)
	538	{
	539	return xenvif_rx_ring_slots_available(queue) \|\|
	540	(queue->vif->stall_timeout &&
	541	(xenvif_rx_queue_stalled(queue) \|\|
	542	xenvif_rx_queue_ready(queue))) \|\|
	543	(test_kthread && kthread_should_stop()) \|\|
	544	queue->vif->disabled;
	545	}
	546
	547	static long xenvif_rx_queue_timeout(struct xenvif_queue *queue)
	548	{
	549	struct sk_buff *skb;
	550	long timeout;
	551
	552	skb = skb_peek(&queue->rx_queue);
	553	if (!skb)
	554	return MAX_SCHEDULE_TIMEOUT;
	555
	556	timeout = XENVIF_RX_CB(skb)->expires - jiffies;
	557	return timeout < 0 ? 0 : timeout;
	558	}
	559
	560	/* Wait until the guest Rx thread has work.
	561	*
	562	* The timeout needs to be adjusted based on the current head of the
	563	* queue (and not just the head at the beginning). In particular, if
	564	* the queue is initially empty an infinite timeout is used and this
	565	* needs to be reduced when a skb is queued.
	566	*
	567	* This cannot be done with wait_event_timeout() because it only
	568	* calculates the timeout once.
	569	*/
	570	static void xenvif_wait_for_rx_work(struct xenvif_queue *queue)
	571	{
	572	DEFINE_WAIT(wait);
	573
	574	if (xenvif_have_rx_work(queue, true))
	575	return;
	576
	577	for (;;) {
	578	long ret;
	579
	580	prepare_to_wait(&queue->wq, &wait, TASK_INTERRUPTIBLE);
	581	if (xenvif_have_rx_work(queue, true))
	582	break;
	583	if (atomic_fetch_andnot(NETBK_RX_EOI \| NETBK_COMMON_EOI,
	584	&queue->eoi_pending) &
	585	(NETBK_RX_EOI \| NETBK_COMMON_EOI))
	586	xen_irq_lateeoi(queue->rx_irq, 0);
	587
	588	ret = schedule_timeout(xenvif_rx_queue_timeout(queue));
	589	if (!ret)
	590	break;
	591	}
	592	finish_wait(&queue->wq, &wait);
	593	}
	594
	595	static void xenvif_queue_carrier_off(struct xenvif_queue *queue)
	596	{
	597	struct xenvif *vif = queue->vif;
	598
	599	queue->stalled = true;
	600
	601	/* At least one queue has stalled? Disable the carrier. */
	602	spin_lock(&vif->lock);
	603	if (vif->stalled_queues++ == 0) {
	604	netdev_info(vif->dev, "Guest Rx stalled");
	605	netif_carrier_off(vif->dev);
	606	}
	607	spin_unlock(&vif->lock);
	608	}
	609
	610	static void xenvif_queue_carrier_on(struct xenvif_queue *queue)
	611	{
	612	struct xenvif *vif = queue->vif;
	613
	614	queue->last_rx_time = jiffies; /* Reset Rx stall detection. */
	615	queue->stalled = false;
	616
	617	/* All queues are ready? Enable the carrier. */
	618	spin_lock(&vif->lock);
	619	if (--vif->stalled_queues == 0) {
	620	netdev_info(vif->dev, "Guest Rx ready");
	621	netif_carrier_on(vif->dev);
	622	}
	623	spin_unlock(&vif->lock);
	624	}
	625
	626	int xenvif_kthread_guest_rx(void *data)
	627	{
	628	struct xenvif_queue *queue = data;
	629	struct xenvif *vif = queue->vif;
	630
	631	if (!vif->stall_timeout)
	632	xenvif_queue_carrier_on(queue);
	633
	634	for (;;) {
	635	xenvif_wait_for_rx_work(queue);
	636
	637	if (kthread_should_stop())
	638	break;
	639
	640	/* This frontend is found to be rogue, disable it in
	641	* kthread context. Currently this is only set when
	642	* netback finds out frontend sends malformed packet,
	643	* but we cannot disable the interface in softirq
	644	* context so we defer it here, if this thread is
	645	* associated with queue 0.
	646	*/
	647	if (unlikely(vif->disabled && queue->id == 0)) {
	648	xenvif_carrier_off(vif);
	649	break;
	650	}
	651
	652	if (!skb_queue_empty(&queue->rx_queue))
	653	xenvif_rx_action(queue);
	654
	655	/* If the guest hasn't provided any Rx slots for a
	656	* while it's probably not responsive, drop the
	657	* carrier so packets are dropped earlier.
	658	*/
	659	if (vif->stall_timeout) {
	660	if (xenvif_rx_queue_stalled(queue))
	661	xenvif_queue_carrier_off(queue);
	662	else if (xenvif_rx_queue_ready(queue))
	663	xenvif_queue_carrier_on(queue);
	664	}
	665
	666	/* Queued packets may have foreign pages from other
	667	* domains. These cannot be queued indefinitely as
	668	* this would starve guests of grant refs and transmit
	669	* slots.
	670	*/
	671	xenvif_rx_queue_drop_expired(queue);
	672
	673	cond_resched();
	674	}
	675
	676	/* Bin any remaining skbs */
	677	xenvif_rx_queue_purge(queue);
	678
	679	return 0;
	680	}