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

From: Jason Wang <[email-masked]>
Date: Mon, 23 Jul 2012 13:48:35 +0800

On 07/20/2012 09:40 PM, Michael S. Tsirkin wrote:
> 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<[email-masked]>
>> Signed-off-by: Jason Wang<[email-masked]>
> 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.

Sure, thanks for the reviewing.
>
> 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?

Sure.
>> @@ -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;
> 	};

Ok.
>> +	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?

Enough, so has_cvq is dupliated with vi->cvq. I will remove it in next 
version.
>
>>   	/* 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?

Yes, will change it to use kzalloc.
>
>> +	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.

Ok.
>> +	}
>>
>> -	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.

Consider the code is really simple, seem no need to use helpers.
>
>>   	}
>> -	return 0;
>> +
>> +err:
>> +	if (ret&&  names)
> If we are here ret != 0. For names, just add another label, don't
> complicate cleanup.

Ok.
>> +		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.
>

Ok.
>> +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.

Ok.
>>   }
>>
>>   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

Will fix this, thanks.
>> +	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?

We can, but as you said, just let the logic simpler a bit.
>> +	/* 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