Re: [net-next RFC V5 4/5] virtio_net: multiqueue support

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On Thu, Jul 05, 2012 at 06:29:53PM +0800, Jason Wang wrote:
> This patch converts virtio_net to a multi queue device. After negotiated
> VIRTIO_NET_F_MULTIQUEUE feature, the virtio device has many tx/rx queue pairs,
> and driver could read the number from config space.
> 
> The driver expects the number of rx/tx queue paris is equal to the number of
> vcpus. To maximize the performance under this per-cpu rx/tx queue pairs, some
> optimization were introduced:
> 
> - Txq selection is based on the processor id in order to avoid contending a lock
>   whose owner may exits to host.
> - Since the txq/txq were per-cpu, affinity hint were set to the cpu that owns
>   the queue pairs.
> 
> Signed-off-by: Krishna Kumar <krkumar2@xxxxxxxxxx>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>

Overall fine. I think it is best to smash the following patch
into this one, so that default behavior does not
jump to mq then back. some comments below: mostly nits, and a minor bug.

If you are worried the patch is too big, it can be split
differently
	- rework to use send_queue/receive_queue structures, no
	  functional changes.
	- add multiqueue

but this is not a must.

> ---
>  drivers/net/virtio_net.c   |  645 ++++++++++++++++++++++++++++++-------------
>  include/linux/virtio_net.h |    2 +
>  2 files changed, 452 insertions(+), 195 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 1db445b..7410187 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -26,6 +26,7 @@
>  #include <linux/scatterlist.h>
>  #include <linux/if_vlan.h>
>  #include <linux/slab.h>
> +#include <linux/interrupt.h>
>  
>  static int napi_weight = 128;
>  module_param(napi_weight, int, 0444);
> @@ -41,6 +42,8 @@ module_param(gso, bool, 0444);
>  #define VIRTNET_SEND_COMMAND_SG_MAX    2
>  #define VIRTNET_DRIVER_VERSION "1.0.0"
>  
> +#define MAX_QUEUES 256
> +
>  struct virtnet_stats {
>  	struct u64_stats_sync tx_syncp;
>  	struct u64_stats_sync rx_syncp;

Would be a bit better not to have artificial limits like that.
Maybe allocate arrays at probe time, then we can
take whatever the device gives us?

> @@ -51,43 +54,69 @@ struct virtnet_stats {
>  	u64 rx_packets;
>  };
>  
> -struct virtnet_info {
> -	struct virtio_device *vdev;
> -	struct virtqueue *rvq, *svq, *cvq;
> -	struct net_device *dev;
> +/* Internal representation of a send virtqueue */
> +struct send_queue {
> +	/* Virtqueue associated with this send _queue */
> +	struct virtqueue *vq;
> +
> +	/* TX: fragments + linear part + virtio header */
> +	struct scatterlist sg[MAX_SKB_FRAGS + 2];
> +};
> +
> +/* Internal representation of a receive virtqueue */
> +struct receive_queue {
> +	/* Virtqueue associated with this receive_queue */
> +	struct virtqueue *vq;
> +
> +	/* Back pointer to the virtnet_info */
> +	struct virtnet_info *vi;
> +
>  	struct napi_struct napi;
> -	unsigned int status;
>  
>  	/* Number of input buffers, and max we've ever had. */
>  	unsigned int num, max;
>  
> +	/* Work struct for refilling if we run low on memory. */
> +	struct delayed_work refill;
> +
> +	/* Chain pages by the private ptr. */
> +	struct page *pages;
> +
> +	/* RX: fragments + linear part + virtio header */
> +	struct scatterlist sg[MAX_SKB_FRAGS + 2];
> +};
> +
> +struct virtnet_info {
> +	u16 num_queue_pairs;		/* # of RX/TX vq pairs */
> +
> +	struct send_queue *sq[MAX_QUEUES] ____cacheline_aligned_in_smp;
> +	struct receive_queue *rq[MAX_QUEUES] ____cacheline_aligned_in_smp;

The assumption is a tx/rx pair is handled on the same cpu, yes?
If yes maybe make it a single array to improve cache locality
a bit?
	struct queue_pair {
		struct send_queue sq;
		struct receive_queue rq;
	};

> +	struct virtqueue *cvq;
> +
> +	struct virtio_device *vdev;
> +	struct net_device *dev;
> +	unsigned int status;
> +
>  	/* I like... big packets and I cannot lie! */
>  	bool big_packets;
>  
>  	/* Host will merge rx buffers for big packets (shake it! shake it!) */
>  	bool mergeable_rx_bufs;
>  
> +	/* Has control virtqueue */
> +	bool has_cvq;
> +

won't checking (cvq != NULL) be enough?

>  	/* enable config space updates */
>  	bool config_enable;
>  
>  	/* Active statistics */
>  	struct virtnet_stats __percpu *stats;
>  
> -	/* Work struct for refilling if we run low on memory. */
> -	struct delayed_work refill;
> -
>  	/* Work struct for config space updates */
>  	struct work_struct config_work;
>  
>  	/* Lock for config space updates */
>  	struct mutex config_lock;
> -
> -	/* Chain pages by the private ptr. */
> -	struct page *pages;
> -
> -	/* fragments + linear part + virtio header */
> -	struct scatterlist rx_sg[MAX_SKB_FRAGS + 2];
> -	struct scatterlist tx_sg[MAX_SKB_FRAGS + 2];
>  };
>  
>  struct skb_vnet_hdr {
> @@ -108,6 +137,22 @@ struct padded_vnet_hdr {
>  	char padding[6];
>  };
>  
> +static inline int txq_get_qnum(struct virtnet_info *vi, struct virtqueue *vq)
> +{
> +	int ret = virtqueue_get_queue_index(vq);
> +
> +	/* skip ctrl vq */
> +	if (vi->has_cvq)
> +		return (ret - 1) / 2;
> +	else
> +		return ret / 2;
> +}
> +
> +static inline int rxq_get_qnum(struct virtnet_info *vi, struct virtqueue *vq)
> +{
> +	return virtqueue_get_queue_index(vq) / 2;
> +}
> +
>  static inline struct skb_vnet_hdr *skb_vnet_hdr(struct sk_buff *skb)
>  {
>  	return (struct skb_vnet_hdr *)skb->cb;
> @@ -117,22 +162,22 @@ static inline struct skb_vnet_hdr *skb_vnet_hdr(struct sk_buff *skb)
>   * private is used to chain pages for big packets, put the whole
>   * most recent used list in the beginning for reuse
>   */
> -static void give_pages(struct virtnet_info *vi, struct page *page)
> +static void give_pages(struct receive_queue *rq, struct page *page)
>  {
>  	struct page *end;
>  
>  	/* Find end of list, sew whole thing into vi->pages. */
>  	for (end = page; end->private; end = (struct page *)end->private);
> -	end->private = (unsigned long)vi->pages;
> -	vi->pages = page;
> +	end->private = (unsigned long)rq->pages;
> +	rq->pages = page;
>  }
>  
> -static struct page *get_a_page(struct virtnet_info *vi, gfp_t gfp_mask)
> +static struct page *get_a_page(struct receive_queue *rq, gfp_t gfp_mask)
>  {
> -	struct page *p = vi->pages;
> +	struct page *p = rq->pages;
>  
>  	if (p) {
> -		vi->pages = (struct page *)p->private;
> +		rq->pages = (struct page *)p->private;
>  		/* clear private here, it is used to chain pages */
>  		p->private = 0;
>  	} else
> @@ -140,15 +185,15 @@ static struct page *get_a_page(struct virtnet_info *vi, gfp_t gfp_mask)
>  	return p;
>  }
>  
> -static void skb_xmit_done(struct virtqueue *svq)
> +static void skb_xmit_done(struct virtqueue *vq)
>  {
> -	struct virtnet_info *vi = svq->vdev->priv;
> +	struct virtnet_info *vi = vq->vdev->priv;
>  
>  	/* Suppress further interrupts. */
> -	virtqueue_disable_cb(svq);
> +	virtqueue_disable_cb(vq);
>  
>  	/* We were probably waiting for more output buffers. */
> -	netif_wake_queue(vi->dev);
> +	netif_wake_subqueue(vi->dev, txq_get_qnum(vi, vq));
>  }
>  
>  static void set_skb_frag(struct sk_buff *skb, struct page *page,
> @@ -167,9 +212,10 @@ static void set_skb_frag(struct sk_buff *skb, struct page *page,
>  }
>  
>  /* Called from bottom half context */
> -static struct sk_buff *page_to_skb(struct virtnet_info *vi,
> +static struct sk_buff *page_to_skb(struct receive_queue *rq,
>  				   struct page *page, unsigned int len)
>  {
> +	struct virtnet_info *vi = rq->vi;
>  	struct sk_buff *skb;
>  	struct skb_vnet_hdr *hdr;
>  	unsigned int copy, hdr_len, offset;
> @@ -225,12 +271,12 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
>  	}
>  
>  	if (page)
> -		give_pages(vi, page);
> +		give_pages(rq, page);
>  
>  	return skb;
>  }
>  
> -static int receive_mergeable(struct virtnet_info *vi, struct sk_buff *skb)
> +static int receive_mergeable(struct receive_queue *rq, struct sk_buff *skb)
>  {
>  	struct skb_vnet_hdr *hdr = skb_vnet_hdr(skb);
>  	struct page *page;
> @@ -244,7 +290,7 @@ static int receive_mergeable(struct virtnet_info *vi, struct sk_buff *skb)
>  			skb->dev->stats.rx_length_errors++;
>  			return -EINVAL;
>  		}
> -		page = virtqueue_get_buf(vi->rvq, &len);
> +		page = virtqueue_get_buf(rq->vq, &len);
>  		if (!page) {
>  			pr_debug("%s: rx error: %d buffers missing\n",
>  				 skb->dev->name, hdr->mhdr.num_buffers);
> @@ -257,13 +303,14 @@ static int receive_mergeable(struct virtnet_info *vi, struct sk_buff *skb)
>  
>  		set_skb_frag(skb, page, 0, &len);
>  
> -		--vi->num;
> +		--rq->num;
>  	}
>  	return 0;
>  }
>  
> -static void receive_buf(struct net_device *dev, void *buf, unsigned int len)
> +static void receive_buf(struct receive_queue *rq, void *buf, unsigned int len)
>  {
> +	struct net_device *dev = rq->vi->dev;
>  	struct virtnet_info *vi = netdev_priv(dev);
>  	struct virtnet_stats *stats = this_cpu_ptr(vi->stats);
>  	struct sk_buff *skb;
> @@ -274,7 +321,7 @@ static void receive_buf(struct net_device *dev, void *buf, unsigned int len)
>  		pr_debug("%s: short packet %i\n", dev->name, len);
>  		dev->stats.rx_length_errors++;
>  		if (vi->mergeable_rx_bufs || vi->big_packets)
> -			give_pages(vi, buf);
> +			give_pages(rq, buf);
>  		else
>  			dev_kfree_skb(buf);
>  		return;
> @@ -286,14 +333,14 @@ static void receive_buf(struct net_device *dev, void *buf, unsigned int len)
>  		skb_trim(skb, len);
>  	} else {
>  		page = buf;
> -		skb = page_to_skb(vi, page, len);
> +		skb = page_to_skb(rq, page, len);
>  		if (unlikely(!skb)) {
>  			dev->stats.rx_dropped++;
> -			give_pages(vi, page);
> +			give_pages(rq, page);
>  			return;
>  		}
>  		if (vi->mergeable_rx_bufs)
> -			if (receive_mergeable(vi, skb)) {
> +			if (receive_mergeable(rq, skb)) {
>  				dev_kfree_skb(skb);
>  				return;
>  			}
> @@ -363,90 +410,91 @@ frame_err:
>  	dev_kfree_skb(skb);
>  }
>  
> -static int add_recvbuf_small(struct virtnet_info *vi, gfp_t gfp)
> +static int add_recvbuf_small(struct receive_queue *rq, gfp_t gfp)
>  {
>  	struct sk_buff *skb;
>  	struct skb_vnet_hdr *hdr;
>  	int err;
>  
> -	skb = __netdev_alloc_skb_ip_align(vi->dev, MAX_PACKET_LEN, gfp);
> +	skb = __netdev_alloc_skb_ip_align(rq->vi->dev, MAX_PACKET_LEN, gfp);
>  	if (unlikely(!skb))
>  		return -ENOMEM;
>  
>  	skb_put(skb, MAX_PACKET_LEN);
>  
>  	hdr = skb_vnet_hdr(skb);
> -	sg_set_buf(vi->rx_sg, &hdr->hdr, sizeof hdr->hdr);
> +	sg_set_buf(rq->sg, &hdr->hdr, sizeof hdr->hdr);
> +
> +	skb_to_sgvec(skb, rq->sg + 1, 0, skb->len);
>  
> -	skb_to_sgvec(skb, vi->rx_sg + 1, 0, skb->len);
> +	err = virtqueue_add_buf(rq->vq, rq->sg, 0, 2, skb, gfp);
>  
> -	err = virtqueue_add_buf(vi->rvq, vi->rx_sg, 0, 2, skb, gfp);
>  	if (err < 0)
>  		dev_kfree_skb(skb);
>  
>  	return err;
>  }
>  
> -static int add_recvbuf_big(struct virtnet_info *vi, gfp_t gfp)
> +static int add_recvbuf_big(struct receive_queue *rq, gfp_t gfp)
>  {
>  	struct page *first, *list = NULL;
>  	char *p;
>  	int i, err, offset;
>  
> -	/* page in vi->rx_sg[MAX_SKB_FRAGS + 1] is list tail */
> +	/* page in rq->sg[MAX_SKB_FRAGS + 1] is list tail */
>  	for (i = MAX_SKB_FRAGS + 1; i > 1; --i) {
> -		first = get_a_page(vi, gfp);
> +		first = get_a_page(rq, gfp);
>  		if (!first) {
>  			if (list)
> -				give_pages(vi, list);
> +				give_pages(rq, list);
>  			return -ENOMEM;
>  		}
> -		sg_set_buf(&vi->rx_sg[i], page_address(first), PAGE_SIZE);
> +		sg_set_buf(&rq->sg[i], page_address(first), PAGE_SIZE);
>  
>  		/* chain new page in list head to match sg */
>  		first->private = (unsigned long)list;
>  		list = first;
>  	}
>  
> -	first = get_a_page(vi, gfp);
> +	first = get_a_page(rq, gfp);
>  	if (!first) {
> -		give_pages(vi, list);
> +		give_pages(rq, list);
>  		return -ENOMEM;
>  	}
>  	p = page_address(first);
>  
> -	/* vi->rx_sg[0], vi->rx_sg[1] share the same page */
> -	/* a separated vi->rx_sg[0] for virtio_net_hdr only due to QEMU bug */
> -	sg_set_buf(&vi->rx_sg[0], p, sizeof(struct virtio_net_hdr));
> +	/* rq->sg[0], rq->sg[1] share the same page */
> +	/* a separated rq->sg[0] for virtio_net_hdr only due to QEMU bug */
> +	sg_set_buf(&rq->sg[0], p, sizeof(struct virtio_net_hdr));
>  
> -	/* vi->rx_sg[1] for data packet, from offset */
> +	/* rq->sg[1] for data packet, from offset */
>  	offset = sizeof(struct padded_vnet_hdr);
> -	sg_set_buf(&vi->rx_sg[1], p + offset, PAGE_SIZE - offset);
> +	sg_set_buf(&rq->sg[1], p + offset, PAGE_SIZE - offset);
>  
>  	/* chain first in list head */
>  	first->private = (unsigned long)list;
> -	err = virtqueue_add_buf(vi->rvq, vi->rx_sg, 0, MAX_SKB_FRAGS + 2,
> +	err = virtqueue_add_buf(rq->vq, rq->sg, 0, MAX_SKB_FRAGS + 2,
>  				first, gfp);
>  	if (err < 0)
> -		give_pages(vi, first);
> +		give_pages(rq, first);
>  
>  	return err;
>  }
>  
> -static int add_recvbuf_mergeable(struct virtnet_info *vi, gfp_t gfp)
> +static int add_recvbuf_mergeable(struct receive_queue *rq, gfp_t gfp)
>  {
>  	struct page *page;
>  	int err;
>  
> -	page = get_a_page(vi, gfp);
> +	page = get_a_page(rq, gfp);
>  	if (!page)
>  		return -ENOMEM;
>  
> -	sg_init_one(vi->rx_sg, page_address(page), PAGE_SIZE);
> +	sg_init_one(rq->sg, page_address(page), PAGE_SIZE);
>  
> -	err = virtqueue_add_buf(vi->rvq, vi->rx_sg, 0, 1, page, gfp);
> +	err = virtqueue_add_buf(rq->vq, rq->sg, 0, 1, page, gfp);
>  	if (err < 0)
> -		give_pages(vi, page);
> +		give_pages(rq, page);
>  
>  	return err;
>  }
> @@ -458,97 +506,104 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi, gfp_t gfp)
>   * before we're receiving packets, or from refill_work which is
>   * careful to disable receiving (using napi_disable).
>   */
> -static bool try_fill_recv(struct virtnet_info *vi, gfp_t gfp)
> +static bool try_fill_recv(struct receive_queue *rq, gfp_t gfp)
>  {
> +	struct virtnet_info *vi = rq->vi;
>  	int err;
>  	bool oom;
>  
>  	do {
>  		if (vi->mergeable_rx_bufs)
> -			err = add_recvbuf_mergeable(vi, gfp);
> +			err = add_recvbuf_mergeable(rq, gfp);
>  		else if (vi->big_packets)
> -			err = add_recvbuf_big(vi, gfp);
> +			err = add_recvbuf_big(rq, gfp);
>  		else
> -			err = add_recvbuf_small(vi, gfp);
> +			err = add_recvbuf_small(rq, gfp);
>  
>  		oom = err == -ENOMEM;
>  		if (err < 0)
>  			break;
> -		++vi->num;
> +		++rq->num;
>  	} while (err > 0);
> -	if (unlikely(vi->num > vi->max))
> -		vi->max = vi->num;
> -	virtqueue_kick(vi->rvq);
> +	if (unlikely(rq->num > rq->max))
> +		rq->max = rq->num;
> +	virtqueue_kick(rq->vq);
>  	return !oom;
>  }
>  
> -static void skb_recv_done(struct virtqueue *rvq)
> +static void skb_recv_done(struct virtqueue *vq)
>  {
> -	struct virtnet_info *vi = rvq->vdev->priv;
> +	struct virtnet_info *vi = vq->vdev->priv;
> +	struct napi_struct *napi = &vi->rq[rxq_get_qnum(vi, vq)]->napi;
> +
>  	/* Schedule NAPI, Suppress further interrupts if successful. */
> -	if (napi_schedule_prep(&vi->napi)) {
> -		virtqueue_disable_cb(rvq);
> -		__napi_schedule(&vi->napi);
> +	if (napi_schedule_prep(napi)) {
> +		virtqueue_disable_cb(vq);
> +		__napi_schedule(napi);
>  	}
>  }
>  
> -static void virtnet_napi_enable(struct virtnet_info *vi)
> +static void virtnet_napi_enable(struct receive_queue *rq)
>  {
> -	napi_enable(&vi->napi);
> +	napi_enable(&rq->napi);
>  
>  	/* If all buffers were filled by other side before we napi_enabled, we
>  	 * won't get another interrupt, so process any outstanding packets
>  	 * now.  virtnet_poll wants re-enable the queue, so we disable here.
>  	 * We synchronize against interrupts via NAPI_STATE_SCHED */
> -	if (napi_schedule_prep(&vi->napi)) {
> -		virtqueue_disable_cb(vi->rvq);
> +	if (napi_schedule_prep(&rq->napi)) {
> +		virtqueue_disable_cb(rq->vq);
>  		local_bh_disable();
> -		__napi_schedule(&vi->napi);
> +		__napi_schedule(&rq->napi);
>  		local_bh_enable();
>  	}
>  }
>  
>  static void refill_work(struct work_struct *work)
>  {
> -	struct virtnet_info *vi;
> +	struct napi_struct *napi;
> +	struct receive_queue *rq;
>  	bool still_empty;
>  
> -	vi = container_of(work, struct virtnet_info, refill.work);
> -	napi_disable(&vi->napi);
> -	still_empty = !try_fill_recv(vi, GFP_KERNEL);
> -	virtnet_napi_enable(vi);
> +	rq = container_of(work, struct receive_queue, refill.work);
> +	napi = &rq->napi;
> +
> +	napi_disable(napi);
> +	still_empty = !try_fill_recv(rq, GFP_KERNEL);
> +	virtnet_napi_enable(rq);
>  
>  	/* In theory, this can happen: if we don't get any buffers in
>  	 * we will *never* try to fill again. */
>  	if (still_empty)
> -		queue_delayed_work(system_nrt_wq, &vi->refill, HZ/2);
> +		queue_delayed_work(system_nrt_wq, &rq->refill, HZ/2);
>  }
>  
>  static int virtnet_poll(struct napi_struct *napi, int budget)
>  {
> -	struct virtnet_info *vi = container_of(napi, struct virtnet_info, napi);
> +	struct receive_queue *rq = container_of(napi, struct receive_queue,
> +						napi);
>  	void *buf;
>  	unsigned int len, received = 0;
>  
>  again:
>  	while (received < budget &&
> -	       (buf = virtqueue_get_buf(vi->rvq, &len)) != NULL) {
> -		receive_buf(vi->dev, buf, len);
> -		--vi->num;
> +	       (buf = virtqueue_get_buf(rq->vq, &len)) != NULL) {
> +		receive_buf(rq, buf, len);
> +		--rq->num;
>  		received++;
>  	}
>  
> -	if (vi->num < vi->max / 2) {
> -		if (!try_fill_recv(vi, GFP_ATOMIC))
> -			queue_delayed_work(system_nrt_wq, &vi->refill, 0);
> +	if (rq->num < rq->max / 2) {
> +		if (!try_fill_recv(rq, GFP_ATOMIC))
> +			queue_delayed_work(system_nrt_wq, &rq->refill, 0);
>  	}
>  
>  	/* Out of packets? */
>  	if (received < budget) {
>  		napi_complete(napi);
> -		if (unlikely(!virtqueue_enable_cb(vi->rvq)) &&
> +		if (unlikely(!virtqueue_enable_cb(rq->vq)) &&
>  		    napi_schedule_prep(napi)) {
> -			virtqueue_disable_cb(vi->rvq);
> +			virtqueue_disable_cb(rq->vq);
>  			__napi_schedule(napi);
>  			goto again;
>  		}
> @@ -557,13 +612,14 @@ again:
>  	return received;
>  }
>  
> -static unsigned int free_old_xmit_skbs(struct virtnet_info *vi)
> +static unsigned int free_old_xmit_skbs(struct virtnet_info *vi,
> +				       struct virtqueue *vq)
>  {
>  	struct sk_buff *skb;
>  	unsigned int len, tot_sgs = 0;
>  	struct virtnet_stats *stats = this_cpu_ptr(vi->stats);
>  
> -	while ((skb = virtqueue_get_buf(vi->svq, &len)) != NULL) {
> +	while ((skb = virtqueue_get_buf(vq, &len)) != NULL) {
>  		pr_debug("Sent skb %p\n", skb);
>  
>  		u64_stats_update_begin(&stats->tx_syncp);
> @@ -577,7 +633,8 @@ static unsigned int free_old_xmit_skbs(struct virtnet_info *vi)
>  	return tot_sgs;
>  }
>  
> -static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb)
> +static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb,
> +		    struct virtqueue *vq, struct scatterlist *sg)
>  {
>  	struct skb_vnet_hdr *hdr = skb_vnet_hdr(skb);
>  	const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
> @@ -615,44 +672,47 @@ static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb)
>  
>  	/* Encode metadata header at front. */
>  	if (vi->mergeable_rx_bufs)
> -		sg_set_buf(vi->tx_sg, &hdr->mhdr, sizeof hdr->mhdr);
> +		sg_set_buf(sg, &hdr->mhdr, sizeof hdr->mhdr);
>  	else
> -		sg_set_buf(vi->tx_sg, &hdr->hdr, sizeof hdr->hdr);
> +		sg_set_buf(sg, &hdr->hdr, sizeof hdr->hdr);
>  
> -	hdr->num_sg = skb_to_sgvec(skb, vi->tx_sg + 1, 0, skb->len) + 1;
> -	return virtqueue_add_buf(vi->svq, vi->tx_sg, hdr->num_sg,
> +	hdr->num_sg = skb_to_sgvec(skb, sg + 1, 0, skb->len) + 1;
> +	return virtqueue_add_buf(vq, sg, hdr->num_sg,
>  				 0, skb, GFP_ATOMIC);
>  }
>  
>  static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
>  {
>  	struct virtnet_info *vi = netdev_priv(dev);
> +	int qnum = skb_get_queue_mapping(skb);
> +	struct virtqueue *vq = vi->sq[qnum]->vq;
>  	int capacity;
>  
>  	/* Free up any pending old buffers before queueing new ones. */
> -	free_old_xmit_skbs(vi);
> +	free_old_xmit_skbs(vi, vq);
>  
>  	/* Try to transmit */
> -	capacity = xmit_skb(vi, skb);
> +	capacity = xmit_skb(vi, skb, vq, vi->sq[qnum]->sg);
>  
>  	/* This can happen with OOM and indirect buffers. */
>  	if (unlikely(capacity < 0)) {
>  		if (likely(capacity == -ENOMEM)) {
>  			if (net_ratelimit())
>  				dev_warn(&dev->dev,
> -					 "TX queue failure: out of memory\n");
> +					"TXQ (%d) failure: out of memory\n",
> +					qnum);
>  		} else {
>  			dev->stats.tx_fifo_errors++;
>  			if (net_ratelimit())
>  				dev_warn(&dev->dev,
> -					 "Unexpected TX queue failure: %d\n",
> -					 capacity);
> +					"Unexpected TXQ (%d) failure: %d\n",
> +					qnum, capacity);
>  		}
>  		dev->stats.tx_dropped++;
>  		kfree_skb(skb);
>  		return NETDEV_TX_OK;
>  	}
> -	virtqueue_kick(vi->svq);
> +	virtqueue_kick(vq);
>  
>  	/* Don't wait up for transmitted skbs to be freed. */
>  	skb_orphan(skb);
> @@ -661,13 +721,13 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
>  	/* Apparently nice girls don't return TX_BUSY; stop the queue
>  	 * before it gets out of hand.  Naturally, this wastes entries. */
>  	if (capacity < 2+MAX_SKB_FRAGS) {
> -		netif_stop_queue(dev);
> -		if (unlikely(!virtqueue_enable_cb_delayed(vi->svq))) {
> +		netif_stop_subqueue(dev, qnum);
> +		if (unlikely(!virtqueue_enable_cb_delayed(vq))) {
>  			/* More just got used, free them then recheck. */
> -			capacity += free_old_xmit_skbs(vi);
> +			capacity += free_old_xmit_skbs(vi, vq);
>  			if (capacity >= 2+MAX_SKB_FRAGS) {
> -				netif_start_queue(dev);
> -				virtqueue_disable_cb(vi->svq);
> +				netif_start_subqueue(dev, qnum);
> +				virtqueue_disable_cb(vq);
>  			}
>  		}
>  	}
> @@ -700,7 +760,8 @@ static struct rtnl_link_stats64 *virtnet_stats(struct net_device *dev,
>  	unsigned int start;
>  
>  	for_each_possible_cpu(cpu) {
> -		struct virtnet_stats *stats = per_cpu_ptr(vi->stats, cpu);
> +		struct virtnet_stats __percpu *stats
> +			= per_cpu_ptr(vi->stats, cpu);
>  		u64 tpackets, tbytes, rpackets, rbytes;
>  
>  		do {
> @@ -734,20 +795,26 @@ static struct rtnl_link_stats64 *virtnet_stats(struct net_device *dev,
>  static void virtnet_netpoll(struct net_device *dev)
>  {
>  	struct virtnet_info *vi = netdev_priv(dev);
> +	int i;
>  
> -	napi_schedule(&vi->napi);
> +	for (i = 0; i < vi->num_queue_pairs; i++)
> +		napi_schedule(&vi->rq[i]->napi);
>  }
>  #endif
>  
>  static int virtnet_open(struct net_device *dev)
>  {
>  	struct virtnet_info *vi = netdev_priv(dev);
> +	int i;
>  
> -	/* Make sure we have some buffers: if oom use wq. */
> -	if (!try_fill_recv(vi, GFP_KERNEL))
> -		queue_delayed_work(system_nrt_wq, &vi->refill, 0);
> +	for (i = 0; i < vi->num_queue_pairs; i++) {
> +		/* Make sure we have some buffers: if oom use wq. */
> +		if (!try_fill_recv(vi->rq[i], GFP_KERNEL))
> +			queue_delayed_work(system_nrt_wq,
> +					   &vi->rq[i]->refill, 0);
> +		virtnet_napi_enable(vi->rq[i]);
> +	}
>  
> -	virtnet_napi_enable(vi);
>  	return 0;
>  }
>  
> @@ -809,10 +876,13 @@ static void virtnet_ack_link_announce(struct virtnet_info *vi)
>  static int virtnet_close(struct net_device *dev)
>  {
>  	struct virtnet_info *vi = netdev_priv(dev);
> +	int i;
>  
>  	/* Make sure refill_work doesn't re-enable napi! */
> -	cancel_delayed_work_sync(&vi->refill);
> -	napi_disable(&vi->napi);
> +	for (i = 0; i < vi->num_queue_pairs; i++) {
> +		cancel_delayed_work_sync(&vi->rq[i]->refill);
> +		napi_disable(&vi->rq[i]->napi);
> +	}
>  
>  	return 0;
>  }
> @@ -924,11 +994,10 @@ static void virtnet_get_ringparam(struct net_device *dev,
>  {
>  	struct virtnet_info *vi = netdev_priv(dev);
>  
> -	ring->rx_max_pending = virtqueue_get_vring_size(vi->rvq);
> -	ring->tx_max_pending = virtqueue_get_vring_size(vi->svq);
> +	ring->rx_max_pending = virtqueue_get_vring_size(vi->rq[0]->vq);
> +	ring->tx_max_pending = virtqueue_get_vring_size(vi->sq[0]->vq);
>  	ring->rx_pending = ring->rx_max_pending;
>  	ring->tx_pending = ring->tx_max_pending;
> -
>  }
>  
>  
> @@ -961,6 +1030,19 @@ static int virtnet_change_mtu(struct net_device *dev, int new_mtu)
>  	return 0;
>  }
>  
> +/* To avoid contending a lock hold by a vcpu who would exit to host, select the
> + * txq based on the processor id.
> + */
> +static u16 virtnet_select_queue(struct net_device *dev, struct sk_buff *skb)
> +{
> +	int txq = skb_rx_queue_recorded(skb) ? skb_get_rx_queue(skb) :
> +		  smp_processor_id();
> +
> +	while (unlikely(txq >= dev->real_num_tx_queues))
> +		txq -= dev->real_num_tx_queues;
> +	return txq;
> +}
> +
>  static const struct net_device_ops virtnet_netdev = {
>  	.ndo_open            = virtnet_open,
>  	.ndo_stop   	     = virtnet_close,
> @@ -972,6 +1054,7 @@ static const struct net_device_ops virtnet_netdev = {
>  	.ndo_get_stats64     = virtnet_stats,
>  	.ndo_vlan_rx_add_vid = virtnet_vlan_rx_add_vid,
>  	.ndo_vlan_rx_kill_vid = virtnet_vlan_rx_kill_vid,
> +	.ndo_select_queue     = virtnet_select_queue,
>  #ifdef CONFIG_NET_POLL_CONTROLLER
>  	.ndo_poll_controller = virtnet_netpoll,
>  #endif
> @@ -1007,10 +1090,10 @@ static void virtnet_config_changed_work(struct work_struct *work)
>  
>  	if (vi->status & VIRTIO_NET_S_LINK_UP) {
>  		netif_carrier_on(vi->dev);
> -		netif_wake_queue(vi->dev);
> +		netif_tx_wake_all_queues(vi->dev);
>  	} else {
>  		netif_carrier_off(vi->dev);
> -		netif_stop_queue(vi->dev);
> +		netif_tx_stop_all_queues(vi->dev);
>  	}
>  done:
>  	mutex_unlock(&vi->config_lock);
> @@ -1023,41 +1106,217 @@ static void virtnet_config_changed(struct virtio_device *vdev)
>  	queue_work(system_nrt_wq, &vi->config_work);
>  }
>  
> -static int init_vqs(struct virtnet_info *vi)
> +static void free_receive_bufs(struct virtnet_info *vi)
> +{
> +	int i;
> +
> +	for (i = 0; i < vi->num_queue_pairs; i++) {
> +		while (vi->rq[i]->pages)
> +			__free_pages(get_a_page(vi->rq[i], GFP_KERNEL), 0);
> +	}
> +}
> +
> +/* Free memory allocated for send and receive queues */
> +static void virtnet_free_queues(struct virtnet_info *vi)
>  {
> -	struct virtqueue *vqs[3];
> -	vq_callback_t *callbacks[] = { skb_recv_done, skb_xmit_done, NULL};
> -	const char *names[] = { "input", "output", "control" };
> -	int nvqs, err;
> +	int i;
>  
> -	/* We expect two virtqueues, receive then send,
> -	 * and optionally control. */
> -	nvqs = virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ) ? 3 : 2;
> +	for (i = 0; i < vi->num_queue_pairs; i++) {
> +		kfree(vi->rq[i]);
> +		vi->rq[i] = NULL;
> +		kfree(vi->sq[i]);
> +		vi->sq[i] = NULL;
> +	}
> +}
>  
> -	err = vi->vdev->config->find_vqs(vi->vdev, nvqs, vqs, callbacks, names);
> -	if (err)
> -		return err;
> +static void free_unused_bufs(struct virtnet_info *vi)
> +{
> +	void *buf;
> +	int i;
> +
> +	for (i = 0; i < vi->num_queue_pairs; i++) {
> +		struct virtqueue *vq = vi->sq[i]->vq;
> +
> +		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
> +			dev_kfree_skb(buf);
> +	}
> +
> +	for (i = 0; i < vi->num_queue_pairs; i++) {
> +		struct virtqueue *vq = vi->rq[i]->vq;
> +
> +		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL) {
> +			if (vi->mergeable_rx_bufs || vi->big_packets)
> +				give_pages(vi->rq[i], buf);
> +			else
> +				dev_kfree_skb(buf);
> +			--vi->rq[i]->num;
> +		}
> +		BUG_ON(vi->rq[i]->num != 0);
> +	}
> +}
> +
> +static void virtnet_set_affinity(struct virtnet_info *vi, bool set)
> +{
> +	int i;
> +
> +	if (vi->num_queue_pairs == 1)
> +		return;
> +
> +	for (i = 0; i < vi->num_queue_pairs; i++) {
> +		int cpu = set ? i : -1;
> +		virtqueue_set_affinity(vi->rq[i]->vq, cpu);
> +		virtqueue_set_affinity(vi->sq[i]->vq, cpu);
> +	}
> +	return;
> +}
> +
> +static void virtnet_del_vqs(struct virtnet_info *vi)
> +{
> +	struct virtio_device *vdev = vi->vdev;
> +
> +	virtnet_set_affinity(vi, false);
> +
> +	vdev->config->del_vqs(vdev);
> +
> +	virtnet_free_queues(vi);
> +}
> +
> +static int virtnet_find_vqs(struct virtnet_info *vi)
> +{
> +	vq_callback_t **callbacks;
> +	struct virtqueue **vqs;
> +	int ret = -ENOMEM;
> +	int i, total_vqs;
> +	char **names;
>  
> -	vi->rvq = vqs[0];
> -	vi->svq = vqs[1];
> +	/*
> +	 * We expect 1 RX virtqueue followed by 1 TX virtqueue, followd by
> +	 * possible control virtqueue and followed by the same
> +	 * 'vi->num_queue_pairs-1' more times
> +	 */
> +	total_vqs = vi->num_queue_pairs * 2 +
> +		    virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ);
> +
> +	/* Allocate space for find_vqs parameters */
> +	vqs = kmalloc(total_vqs * sizeof(*vqs), GFP_KERNEL);
> +	callbacks = kmalloc(total_vqs * sizeof(*callbacks), GFP_KERNEL);
> +	names = kmalloc(total_vqs * sizeof(*names), GFP_KERNEL);

so this needs to be kzalloc otherwise on an error cleanup will
get uninitialized data and crash?

> +	if (!vqs || !callbacks || !names)
> +		goto err;
> +
> +	/* Parameters for control virtqueue, if any */
> +	if (vi->has_cvq) {
> +		callbacks[2] = NULL;
> +		names[2] = "control";
> +	}
> +
> +	/* Allocate/initialize parameters for send/receive virtqueues */
> +	for (i = 0; i < vi->num_queue_pairs * 2; i += 2) {
> +		int j = (i == 0 ? i : i + vi->has_cvq);
> +		callbacks[j] = skb_recv_done;
> +		callbacks[j + 1] = skb_xmit_done;
> +		names[j] = kasprintf(GFP_KERNEL, "input.%d", i / 2);
> +		names[j + 1] = kasprintf(GFP_KERNEL, "output.%d", i / 2);

This needs wrappers. E.g. virtnet_rx_vq(int queue_pair), virtnet_tx_vq(int queue_pair);
Then you would just scan 0 to num_queue_pairs, and i is queue pair
number.

> +	}
>  
> -	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ)) {
> +	ret = vi->vdev->config->find_vqs(vi->vdev, total_vqs, vqs, callbacks,
> +					 (const char **)names);
> +	if (ret)
> +		goto err;
> +
> +	if (vi->has_cvq)
>  		vi->cvq = vqs[2];
>  
> -		if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VLAN))
> -			vi->dev->features |= NETIF_F_HW_VLAN_FILTER;
> +	for (i = 0; i < vi->num_queue_pairs * 2; i += 2) {
> +		int j = i == 0 ? i : i + vi->has_cvq;
> +		vi->rq[i / 2]->vq = vqs[j];
> +		vi->sq[i / 2]->vq = vqs[j + 1];

Same here.

>  	}
> -	return 0;
> +
> +err:
> +	if (ret && names)

If we are here ret != 0. For names, just add another label, don't
complicate cleanup.

> +		for (i = 0; i < vi->num_queue_pairs * 2; i++)
> +			kfree(names[i]);
> +
> +	kfree(names);
> +	kfree(callbacks);
> +	kfree(vqs);
> +
> +	return ret;
> +}
> +
> +static int virtnet_alloc_queues(struct virtnet_info *vi)
> +{
> +	int ret = -ENOMEM;
> +	int i;
> +
> +	for (i = 0; i < vi->num_queue_pairs; i++) {
> +		vi->rq[i] = kzalloc(sizeof(*vi->rq[i]), GFP_KERNEL);
> +		vi->sq[i] = kzalloc(sizeof(*vi->sq[i]), GFP_KERNEL);
> +		if (!vi->rq[i] || !vi->sq[i])
> +			goto err;
> +	}
> +
> +	ret = 0;
> +
> +	/* setup initial receive and send queue parameters */
> +	for (i = 0; i < vi->num_queue_pairs; i++) {
> +		vi->rq[i]->vi = vi;
> +		vi->rq[i]->pages = NULL;
> +		INIT_DELAYED_WORK(&vi->rq[i]->refill, refill_work);
> +		netif_napi_add(vi->dev, &vi->rq[i]->napi, virtnet_poll,
> +			       napi_weight);
> +
> +		sg_init_table(vi->rq[i]->sg, ARRAY_SIZE(vi->rq[i]->sg));
> +		sg_init_table(vi->sq[i]->sg, ARRAY_SIZE(vi->sq[i]->sg));
> +	}
> +

Add return 0 here, then ret = 0 will not be needed
above and if (ret) below.


> +err:
> +	if (ret)
> +		virtnet_free_queues(vi);
> +
> +	return ret;
> +}
> +
> +static int virtnet_setup_vqs(struct virtnet_info *vi)
> +{
> +	int ret;
> +
> +	/* Allocate send & receive queues */
> +	ret = virtnet_alloc_queues(vi);
> +	if (!ret) {
> +		ret = virtnet_find_vqs(vi);
> +		if (ret)
> +			virtnet_free_queues(vi);
> +		else
> +			virtnet_set_affinity(vi, true);
> +	}
> +
> +	return ret;

Add some labels for error handling, this if nesting is messy.

>  }
>  
>  static int virtnet_probe(struct virtio_device *vdev)
>  {
> -	int err;
> +	int i, err;
>  	struct net_device *dev;
>  	struct virtnet_info *vi;
> +	u16 num_queues, num_queue_pairs;
> +
> +	/* Find if host supports multiqueue virtio_net device */
> +	err = virtio_config_val(vdev, VIRTIO_NET_F_MULTIQUEUE,
> +				offsetof(struct virtio_net_config,
> +				num_queues), &num_queues);
> +
> +	/* We need atleast 2 queue's */

typo

> +	if (err || num_queues < 2)
> +		num_queues = 2;
> +	if (num_queues > MAX_QUEUES * 2)
> +		num_queues = MAX_QUEUES;
> +
> +	num_queue_pairs = num_queues / 2;
>  
>  	/* Allocate ourselves a network device with room for our info */
> -	dev = alloc_etherdev(sizeof(struct virtnet_info));
> +	dev = alloc_etherdev_mq(sizeof(struct virtnet_info), num_queue_pairs);
>  	if (!dev)
>  		return -ENOMEM;
>  
> @@ -1103,22 +1362,18 @@ static int virtnet_probe(struct virtio_device *vdev)
>  
>  	/* Set up our device-specific information */
>  	vi = netdev_priv(dev);
> -	netif_napi_add(dev, &vi->napi, virtnet_poll, napi_weight);
>  	vi->dev = dev;
>  	vi->vdev = vdev;
>  	vdev->priv = vi;
> -	vi->pages = NULL;
>  	vi->stats = alloc_percpu(struct virtnet_stats);
>  	err = -ENOMEM;
>  	if (vi->stats == NULL)
> -		goto free;
> +		goto free_netdev;
>  
> -	INIT_DELAYED_WORK(&vi->refill, refill_work);
>  	mutex_init(&vi->config_lock);
>  	vi->config_enable = true;
>  	INIT_WORK(&vi->config_work, virtnet_config_changed_work);
> -	sg_init_table(vi->rx_sg, ARRAY_SIZE(vi->rx_sg));
> -	sg_init_table(vi->tx_sg, ARRAY_SIZE(vi->tx_sg));
> +	vi->num_queue_pairs = num_queue_pairs;
>  
>  	/* If we can receive ANY GSO packets, we must allocate large ones. */
>  	if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
> @@ -1129,9 +1384,17 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
>  		vi->mergeable_rx_bufs = true;
>  
> -	err = init_vqs(vi);
> +	if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
> +		vi->has_cvq = true;
> +

How about we disable multiqueue if there's no cvq?
Will make logic a bit simpler, won't it?

> +	/* Allocate/initialize the rx/tx queues, and invoke find_vqs */
> +	err = virtnet_setup_vqs(vi);
>  	if (err)
> -		goto free_stats;
> +		goto free_netdev;
> +
> +	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ) &&
> +	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VLAN))
> +		dev->features |= NETIF_F_HW_VLAN_FILTER;
>  
>  	err = register_netdev(dev);
>  	if (err) {
> @@ -1140,12 +1403,15 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	}
>  
>  	/* Last of all, set up some receive buffers. */
> -	try_fill_recv(vi, GFP_KERNEL);
> -
> -	/* If we didn't even get one input buffer, we're useless. */
> -	if (vi->num == 0) {
> -		err = -ENOMEM;
> -		goto unregister;
> +	for (i = 0; i < num_queue_pairs; i++) {
> +		try_fill_recv(vi->rq[i], GFP_KERNEL);
> +
> +		/* If we didn't even get one input buffer, we're useless. */
> +		if (vi->rq[i]->num == 0) {
> +			free_unused_bufs(vi);
> +			err = -ENOMEM;
> +			goto free_recv_bufs;
> +		}
>  	}
>  
>  	/* Assume link up if device can't report link status,
> @@ -1158,42 +1424,25 @@ static int virtnet_probe(struct virtio_device *vdev)
>  		netif_carrier_on(dev);
>  	}
>  
> -	pr_debug("virtnet: registered device %s\n", dev->name);
> +	pr_debug("virtnet: registered device %s with %d RX and TX vq's\n",
> +		 dev->name, num_queue_pairs);
> +
>  	return 0;
>  
> -unregister:
> +free_recv_bufs:
> +	free_receive_bufs(vi);
>  	unregister_netdev(dev);
> +
>  free_vqs:
> -	vdev->config->del_vqs(vdev);
> -free_stats:
> -	free_percpu(vi->stats);
> -free:
> +	for (i = 0; i < num_queue_pairs; i++)
> +		cancel_delayed_work_sync(&vi->rq[i]->refill);
> +	virtnet_del_vqs(vi);
> +
> +free_netdev:
>  	free_netdev(dev);
>  	return err;
>  }
>  
> -static void free_unused_bufs(struct virtnet_info *vi)
> -{
> -	void *buf;
> -	while (1) {
> -		buf = virtqueue_detach_unused_buf(vi->svq);
> -		if (!buf)
> -			break;
> -		dev_kfree_skb(buf);
> -	}
> -	while (1) {
> -		buf = virtqueue_detach_unused_buf(vi->rvq);
> -		if (!buf)
> -			break;
> -		if (vi->mergeable_rx_bufs || vi->big_packets)
> -			give_pages(vi, buf);
> -		else
> -			dev_kfree_skb(buf);
> -		--vi->num;
> -	}
> -	BUG_ON(vi->num != 0);
> -}
> -
>  static void remove_vq_common(struct virtnet_info *vi)
>  {
>  	vi->vdev->config->reset(vi->vdev);
> @@ -1201,10 +1450,9 @@ static void remove_vq_common(struct virtnet_info *vi)
>  	/* Free unused buffers in both send and recv, if any. */
>  	free_unused_bufs(vi);
>  
> -	vi->vdev->config->del_vqs(vi->vdev);
> +	free_receive_bufs(vi);
>  
> -	while (vi->pages)
> -		__free_pages(get_a_page(vi, GFP_KERNEL), 0);
> +	virtnet_del_vqs(vi);
>  }
>  
>  static void __devexit virtnet_remove(struct virtio_device *vdev)
> @@ -1230,6 +1478,7 @@ static void __devexit virtnet_remove(struct virtio_device *vdev)
>  static int virtnet_freeze(struct virtio_device *vdev)
>  {
>  	struct virtnet_info *vi = vdev->priv;
> +	int i;
>  
>  	/* Prevent config work handler from accessing the device */
>  	mutex_lock(&vi->config_lock);
> @@ -1237,10 +1486,13 @@ static int virtnet_freeze(struct virtio_device *vdev)
>  	mutex_unlock(&vi->config_lock);
>  
>  	netif_device_detach(vi->dev);
> -	cancel_delayed_work_sync(&vi->refill);
> +	for (i = 0; i < vi->num_queue_pairs; i++)
> +		cancel_delayed_work_sync(&vi->rq[i]->refill);
>  
>  	if (netif_running(vi->dev))
> -		napi_disable(&vi->napi);
> +		for (i = 0; i < vi->num_queue_pairs; i++)
> +			napi_disable(&vi->rq[i]->napi);
> +
>  
>  	remove_vq_common(vi);
>  
> @@ -1252,19 +1504,22 @@ static int virtnet_freeze(struct virtio_device *vdev)
>  static int virtnet_restore(struct virtio_device *vdev)
>  {
>  	struct virtnet_info *vi = vdev->priv;
> -	int err;
> +	int err, i;
>  
> -	err = init_vqs(vi);
> +	err = virtnet_setup_vqs(vi);
>  	if (err)
>  		return err;
>  
>  	if (netif_running(vi->dev))
> -		virtnet_napi_enable(vi);
> +		for (i = 0; i < vi->num_queue_pairs; i++)
> +			virtnet_napi_enable(vi->rq[i]);
>  
>  	netif_device_attach(vi->dev);
>  
> -	if (!try_fill_recv(vi, GFP_KERNEL))
> -		queue_delayed_work(system_nrt_wq, &vi->refill, 0);
> +	for (i = 0; i < vi->num_queue_pairs; i++)
> +		if (!try_fill_recv(vi->rq[i], GFP_KERNEL))
> +			queue_delayed_work(system_nrt_wq,
> +					   &vi->rq[i]->refill, 0);
>  
>  	mutex_lock(&vi->config_lock);
>  	vi->config_enable = true;
> @@ -1287,7 +1542,7 @@ static unsigned int features[] = {
>  	VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_UFO,
>  	VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ,
>  	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
> -	VIRTIO_NET_F_GUEST_ANNOUNCE,
> +	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MULTIQUEUE,
>  };
>  
>  static struct virtio_driver virtio_net_driver = {
> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> index 1bc7e30..60f09ff 100644
> --- a/include/linux/virtio_net.h
> +++ b/include/linux/virtio_net.h
> @@ -61,6 +61,8 @@ struct virtio_net_config {
>  	__u8 mac[6];
>  	/* See VIRTIO_NET_F_STATUS and VIRTIO_NET_S_* above */
>  	__u16 status;
> +	/* Total number of RX/TX queues */
> +	__u16 num_queues;
>  } __attribute__((packed));
>  
>  /* This is the first element of the scatter-gather list.  If you don't
> -- 
> 1.7.1
--
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