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    Subject[net-next RFC V4 PATCH 4/4] virtio_net: multiqueue support
    Date
    This addes multiqueue support to virtio_net driver. This feature is negotiated
    through VIRTIO_NET_F_MULTIQUEUE.

    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@in.ibm.com>
    Signed-off-by: Jason Wang <jasowang@redhat.com>
    ---
    drivers/net/virtio_net.c | 695 ++++++++++++++++++++++++++++++++------------
    include/linux/virtio_net.h | 2 +
    2 files changed, 506 insertions(+), 191 deletions(-)

    diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
    index f18149a..5c719de 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);
    @@ -51,43 +52,73 @@ 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];
    +
    + cpumask_var_t affinity_mask;
    +};
    +
    +/* 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];
    +
    + cpumask_var_t affinity_mask;
    +};
    +
    +struct virtnet_info {
    + int num_queue_pairs; /* # of RX/TX vq pairs */
    +
    + 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;
    +
    /* 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 +139,22 @@ 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 +164,22 @@ 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 +187,15 @@ 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 +214,10 @@ 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 +273,12 @@ 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 +292,7 @@ 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 +305,14 @@ 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 +323,7 @@ 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 +335,14 @@ 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 +412,91 @@ 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, vi->rx_sg + 1, 0, skb->len);
    + skb_to_sgvec(skb, rq->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 +508,104 @@ 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 +614,14 @@ 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 +635,8 @@ 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 +674,47 @@ 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 +723,13 @@ 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 +762,8 @@ 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 +797,31 @@ 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 void free_stats(struct virtnet_info *vi)
    +{
    + free_percpu(vi->stats);
    +}
    +
    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 +883,13 @@ 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 +1001,10 @@ 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 +1037,19 @@ 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 +1061,7 @@ 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 +1097,10 @@ 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 +1113,252 @@ 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 free_rq_sq(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;
    + free_stats(vi);

    - err = vi->vdev->config->find_vqs(vi->vdev, nvqs, vqs, callbacks, names);
    - if (err)
    - return err;
    + if (vi->rq) {
    + for (i = 0; i < vi->num_queue_pairs; i++)
    + kfree(vi->rq[i]);
    + kfree(vi->rq);
    + }
    +
    + if (vi->sq) {
    + for (i = 0; i < vi->num_queue_pairs; i++)
    + kfree(vi->sq[i]);
    + kfree(vi->sq);
    + }
    +}
    +
    +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;

    - vi->rvq = vqs[0];
    - vi->svq = vqs[1];
    + 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 int virtnet_find_vqs(struct virtnet_info *vi)
    +{
    + vq_callback_t **callbacks;
    + struct virtqueue **vqs;
    + int ret = -ENOMEM;
    + int i, total_vqs;
    + char **names;
    +
    + /*
    + * 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);
    + 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);
    + }

    - 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];
    }
    +
    +err:
    + if (ret && names)
    + for (i = 0; i < vi->num_queue_pairs * 2; i++)
    + kfree(names[i]);
    +
    + kfree(names);
    + kfree(callbacks);
    + kfree(vqs);
    +
    + return ret;
    +}
    +
    +static int allocate_queues(struct virtnet_info *vi)
    +{
    + int ret = -ENOMEM;
    + int i;
    +
    + vi->rq = kcalloc(vi->num_queue_pairs, sizeof(*vi->rq), GFP_KERNEL);
    + vi->sq = kcalloc(vi->num_queue_pairs, sizeof(*vi->sq), GFP_KERNEL);
    + if (!vi->sq || !vi->rq)
    + goto err;
    +
    + 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));
    + }
    +
    +err:
    + if (ret)
    + free_rq_sq(vi);
    +
    + return ret;
    +}
    +
    +static int virtnet_setup_vqs(struct virtnet_info *vi)
    +{
    + int ret;
    +
    + /* Allocate send & receive queues */
    + ret = allocate_queues(vi);
    + if (!ret) {
    + ret = virtnet_find_vqs(vi);
    + if (ret)
    + free_rq_sq(vi);
    + }
    +
    + return ret;
    +}
    +
    +static void _virtnet_free_affinity(struct virtnet_info *vi, int i)
    +{
    + struct virtio_device *vdev = vi->vdev;
    + int irq;
    +
    + while (i) {
    + i--;
    + irq = vdev->config->get_vq_irq(vdev, vi->rq[i]->vq);
    + irq_set_affinity_hint(irq, NULL);
    + free_cpumask_var(vi->rq[i]->affinity_mask);
    + irq = vdev->config->get_vq_irq(vdev, vi->sq[i]->vq);
    + irq_set_affinity_hint(irq, NULL);
    + free_cpumask_var(vi->sq[i]->affinity_mask);
    + }
    +}
    +
    +static int virtnet_init_affinity(struct virtnet_info *vi)
    +{
    + struct virtio_device *vdev = vi->vdev;
    + int i, irq;
    +
    + for (i = 0; i < vi->num_queue_pairs; i++) {
    + if (!alloc_cpumask_var(&vi->rq[i]->affinity_mask, GFP_KERNEL))
    + goto err_out;
    + if (!alloc_cpumask_var(&vi->sq[i]->affinity_mask, GFP_KERNEL)) {
    + free_cpumask_var(vi->rq[i]->affinity_mask);
    + goto err_out;
    + }
    + cpumask_set_cpu(i, vi->rq[i]->affinity_mask);
    + cpumask_set_cpu(i, vi->sq[i]->affinity_mask);
    +
    + irq = vdev->config->get_vq_irq(vdev, vi->rq[i]->vq);
    + if (irq_set_affinity_hint(irq, vi->rq[i]->affinity_mask))
    + goto err_out;
    + irq = vdev->config->get_vq_irq(vdev, vi->sq[i]->vq);
    + if (irq_set_affinity_hint(irq, vi->sq[i]->affinity_mask)) {
    + irq = vdev->config->get_vq_irq(vdev, vi->rq[i]->vq);
    + irq_set_affinity_hint(irq, NULL);
    + goto err_out;
    + }
    + }
    +
    return 0;
    +err_out:
    + _virtnet_free_affinity(vi, i);
    + return -ENOMEM;
    +}
    +
    +static void virtnet_free_affinity(struct virtnet_info *vi)
    +{
    + _virtnet_free_affinity(vi, vi->num_queue_pairs);
    }

    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 */
    + if (err || num_queues < 2)
    + num_queues = 2;
    +
    + 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 +1404,18 @@ 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 +1426,17 @@ 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;
    +
    + /* 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 +1445,21 @@ static int virtnet_probe(struct virtio_device *vdev)
    }

    /* Last of all, set up some receive buffers. */
    - try_fill_recv(vi, GFP_KERNEL);
    + 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;
    + }
    + }

    - /* If we didn't even get one input buffer, we're useless. */
    - if (vi->num == 0) {
    - err = -ENOMEM;
    - goto unregister;
    + err = virtnet_init_affinity(vi);
    + if (err) {
    + pr_debug("virtio_net: fail to initialize irq affinity\n");
    + goto free_recv_bufs;
    }

    /* Assume link up if device can't report link status,
    @@ -1158,42 +1472,26 @@ 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:
    + for (i = 0; i < num_queue_pairs; i++)
    + cancel_delayed_work_sync(&vi->rq[i]->refill);
    vdev->config->del_vqs(vdev);
    -free_stats:
    - free_percpu(vi->stats);
    -free:
    +
    +free_netdev:
    + free_rq_sq(vi);
    +
    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);
    @@ -1203,14 +1501,17 @@ static void remove_vq_common(struct virtnet_info *vi)

    vi->vdev->config->del_vqs(vi->vdev);

    - while (vi->pages)
    - __free_pages(get_a_page(vi, GFP_KERNEL), 0);
    + free_receive_bufs(vi);
    }

    static void __devexit virtnet_remove(struct virtio_device *vdev)
    {
    struct virtnet_info *vi = vdev->priv;

    + /* Stop all the virtqueues. */
    + vdev->config->reset(vdev);
    +
    +
    /* Prevent config work handler from accessing the device. */
    mutex_lock(&vi->config_lock);
    vi->config_enable = false;
    @@ -1220,6 +1521,11 @@ static void __devexit virtnet_remove(struct virtio_device *vdev)

    remove_vq_common(vi);

    + virtnet_free_affinity(vi);
    +
    + /* Free memory for send and receive queues */
    + free_rq_sq(vi);
    +
    flush_work(&vi->config_work);

    free_percpu(vi->stats);
    @@ -1230,6 +1536,7 @@ 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 +1544,13 @@ 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 +1562,22 @@ 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 +1600,7 @@ 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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