OSCL-LXR linux-6.0.1/​drivers/​net/​virtio_net.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /* A network driver using virtio.
  *
  * Copyright 2007 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
  */
 //#define DEBUG
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/ethtool.h>
 #include <linux/module.h>
 #include <linux/virtio.h>
 #include <linux/virtio_net.h>
 #include <linux/bpf.h>
 #include <linux/bpf_trace.h>
 #include <linux/scatterlist.h>
 #include <linux/if_vlan.h>
 #include <linux/slab.h>
 #include <linux/cpu.h>
 #include <linux/average.h>
 #include <linux/filter.h>
 #include <linux/kernel.h>
 #include <net/route.h>
 #include <net/xdp.h>
 #include <net/net_failover.h>
 
 static int napi_weight = NAPI_POLL_WEIGHT;
 module_param(napi_weight, int, 0444);
 
 static bool csum = true, gso = true, napi_tx = true;
 module_param(csum, bool, 0444);
 module_param(gso, bool, 0444);
 module_param(napi_tx, bool, 0644);
 
 /* FIXME: MTU in config. */
 #define GOOD_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN)
 #define GOOD_COPY_LEN   128
 
 #define VIRTNET_RX_PAD (NET_IP_ALIGN + NET_SKB_PAD)
 
 /* Amount of XDP headroom to prepend to packets for use by xdp_adjust_head */
 #define VIRTIO_XDP_HEADROOM 256
 
 /* Separating two types of XDP xmit */
 #define VIRTIO_XDP_TX       BIT(0)
 #define VIRTIO_XDP_REDIR    BIT(1)
 
 #define VIRTIO_XDP_FLAG BIT(0)
 
 /* RX packet size EWMA. The average packet size is used to determine the packet
  * buffer size when refilling RX rings. As the entire RX ring may be refilled
  * at once, the weight is chosen so that the EWMA will be insensitive to short-
  * term, transient changes in packet size.
  */
 DECLARE_EWMA(pkt_len, 0, 64)
 
 #define VIRTNET_DRIVER_VERSION "1.0.0"
 
 static const unsigned long guest_offloads[] = {
     VIRTIO_NET_F_GUEST_TSO4,
     VIRTIO_NET_F_GUEST_TSO6,
     VIRTIO_NET_F_GUEST_ECN,
     VIRTIO_NET_F_GUEST_UFO,
     VIRTIO_NET_F_GUEST_CSUM
 };
 
 #define GUEST_OFFLOAD_GRO_HW_MASK ((1ULL << VIRTIO_NET_F_GUEST_TSO4) | \
                 (1ULL << VIRTIO_NET_F_GUEST_TSO6) | \
                 (1ULL << VIRTIO_NET_F_GUEST_ECN)  | \
                 (1ULL << VIRTIO_NET_F_GUEST_UFO))
 
 struct virtnet_stat_desc {
     char desc[ETH_GSTRING_LEN];
     size_t offset;
 };
 
 struct virtnet_sq_stats {
     struct u64_stats_sync syncp;
     u64 packets;
     u64 bytes;
     u64 xdp_tx;
     u64 xdp_tx_drops;
     u64 kicks;
     u64 tx_timeouts;
 };
 
 struct virtnet_rq_stats {
     struct u64_stats_sync syncp;
     u64 packets;
     u64 bytes;
     u64 drops;
     u64 xdp_packets;
     u64 xdp_tx;
     u64 xdp_redirects;
     u64 xdp_drops;
     u64 kicks;
 };
 
 #define VIRTNET_SQ_STAT(m)  offsetof(struct virtnet_sq_stats, m)
 #define VIRTNET_RQ_STAT(m)  offsetof(struct virtnet_rq_stats, m)
 
 static const struct virtnet_stat_desc virtnet_sq_stats_desc[] = {
     { "packets",        VIRTNET_SQ_STAT(packets) },
     { "bytes",      VIRTNET_SQ_STAT(bytes) },
     { "xdp_tx",     VIRTNET_SQ_STAT(xdp_tx) },
     { "xdp_tx_drops",   VIRTNET_SQ_STAT(xdp_tx_drops) },
     { "kicks",      VIRTNET_SQ_STAT(kicks) },
     { "tx_timeouts",    VIRTNET_SQ_STAT(tx_timeouts) },
 };
 
 static const struct virtnet_stat_desc virtnet_rq_stats_desc[] = {
     { "packets",        VIRTNET_RQ_STAT(packets) },
     { "bytes",      VIRTNET_RQ_STAT(bytes) },
     { "drops",      VIRTNET_RQ_STAT(drops) },
     { "xdp_packets",    VIRTNET_RQ_STAT(xdp_packets) },
     { "xdp_tx",     VIRTNET_RQ_STAT(xdp_tx) },
     { "xdp_redirects",  VIRTNET_RQ_STAT(xdp_redirects) },
     { "xdp_drops",      VIRTNET_RQ_STAT(xdp_drops) },
     { "kicks",      VIRTNET_RQ_STAT(kicks) },
 };
 
 #define VIRTNET_SQ_STATS_LEN    ARRAY_SIZE(virtnet_sq_stats_desc)
 #define VIRTNET_RQ_STATS_LEN    ARRAY_SIZE(virtnet_rq_stats_desc)
 
 /* 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];
 
     /* Name of the send queue: output.$index */
     char name[40];
 
     struct virtnet_sq_stats stats;
 
     struct napi_struct napi;
 
     /* Record whether sq is in reset state. */
     bool reset;
 };
 
 /* Internal representation of a receive virtqueue */
 struct receive_queue {
     /* Virtqueue associated with this receive_queue */
     struct virtqueue *vq;
 
     struct napi_struct napi;
 
     struct bpf_prog __rcu *xdp_prog;
 
     struct virtnet_rq_stats stats;
 
     /* Chain pages by the private ptr. */
     struct page *pages;
 
     /* Average packet length for mergeable receive buffers. */
     struct ewma_pkt_len mrg_avg_pkt_len;
 
     /* Page frag for packet buffer allocation. */
     struct page_frag alloc_frag;
 
     /* RX: fragments + linear part + virtio header */
     struct scatterlist sg[MAX_SKB_FRAGS + 2];
 
     /* Min single buffer size for mergeable buffers case. */
     unsigned int min_buf_len;
 
     /* Name of this receive queue: input.$index */
     char name[40];
 
     struct xdp_rxq_info xdp_rxq;
 };
 
 /* This structure can contain rss message with maximum settings for indirection table and keysize
  * Note, that default structure that describes RSS configuration virtio_net_rss_config
  * contains same info but can't handle table values.
  * In any case, structure would be passed to virtio hw through sg_buf split by parts
  * because table sizes may be differ according to the device configuration.
  */
 #define VIRTIO_NET_RSS_MAX_KEY_SIZE     40
 #define VIRTIO_NET_RSS_MAX_TABLE_LEN    128
 struct virtio_net_ctrl_rss {
     u32 hash_types;
     u16 indirection_table_mask;
     u16 unclassified_queue;
     u16 indirection_table[VIRTIO_NET_RSS_MAX_TABLE_LEN];
     u16 max_tx_vq;
     u8 hash_key_length;
     u8 key[VIRTIO_NET_RSS_MAX_KEY_SIZE];
 };
 
 /* Control VQ buffers: protected by the rtnl lock */
 struct control_buf {
     struct virtio_net_ctrl_hdr hdr;
     virtio_net_ctrl_ack status;
     struct virtio_net_ctrl_mq mq;
     u8 promisc;
     u8 allmulti;
     __virtio16 vid;
     __virtio64 offloads;
     struct virtio_net_ctrl_rss rss;
 };
 
 struct virtnet_info {
     struct virtio_device *vdev;
     struct virtqueue *cvq;
     struct net_device *dev;
     struct send_queue *sq;
     struct receive_queue *rq;
     unsigned int status;
 
     /* Max # of queue pairs supported by the device */
     u16 max_queue_pairs;
 
     /* # of queue pairs currently used by the driver */
     u16 curr_queue_pairs;
 
     /* # of XDP queue pairs currently used by the driver */
     u16 xdp_queue_pairs;
 
     /* xdp_queue_pairs may be 0, when xdp is already loaded. So add this. */
     bool xdp_enabled;
 
     /* 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;
 
     /* Host supports rss and/or hash report */
     bool has_rss;
     bool has_rss_hash_report;
     u8 rss_key_size;
     u16 rss_indir_table_size;
     u32 rss_hash_types_supported;
     u32 rss_hash_types_saved;
 
     /* Has control virtqueue */
     bool has_cvq;
 
     /* Host can handle any s/g split between our header and packet data */
     bool any_header_sg;
 
     /* Packet virtio header size */
     u8 hdr_len;
 
     /* Work struct for delayed refilling if we run low on memory. */
     struct delayed_work refill;
 
     /* Is delayed refill enabled? */
     bool refill_enabled;
 
     /* The lock to synchronize the access to refill_enabled */
     spinlock_t refill_lock;
 
     /* Work struct for config space updates */
     struct work_struct config_work;
 
     /* Does the affinity hint is set for virtqueues? */
     bool affinity_hint_set;
 
     /* CPU hotplug instances for online & dead */
     struct hlist_node node;
     struct hlist_node node_dead;
 
     struct control_buf *ctrl;
 
     /* Ethtool settings */
     u8 duplex;
     u32 speed;
 
     /* Interrupt coalescing settings */
     u32 tx_usecs;
     u32 rx_usecs;
     u32 tx_max_packets;
     u32 rx_max_packets;
 
     unsigned long guest_offloads;
     unsigned long guest_offloads_capable;
 
     /* failover when STANDBY feature enabled */
     struct failover *failover;
 };
 
 struct padded_vnet_hdr {
     struct virtio_net_hdr_v1_hash hdr;
     /*
      * hdr is in a separate sg buffer, and data sg buffer shares same page
      * with this header sg. This padding makes next sg 16 byte aligned
      * after the header.
      */
     char padding[12];
 };
 
 static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf);
 static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf);
 
 static bool is_xdp_frame(void *ptr)
 {
     return (unsigned long)ptr & VIRTIO_XDP_FLAG;
 }
 
 static void *xdp_to_ptr(struct xdp_frame *ptr)
 {
     return (void *)((unsigned long)ptr | VIRTIO_XDP_FLAG);
 }
 
 static struct xdp_frame *ptr_to_xdp(void *ptr)
 {
     return (struct xdp_frame *)((unsigned long)ptr & ~VIRTIO_XDP_FLAG);
 }
 
 /* Converting between virtqueue no. and kernel tx/rx queue no.
  * 0:rx0 1:tx0 2:rx1 3:tx1 ... 2N:rxN 2N+1:txN 2N+2:cvq
  */
 static int vq2txq(struct virtqueue *vq)
 {
     return (vq->index - 1) / 2;
 }
 
 static int txq2vq(int txq)
 {
     return txq * 2 + 1;
 }
 
 static int vq2rxq(struct virtqueue *vq)
 {
     return vq->index / 2;
 }
 
 static int rxq2vq(int rxq)
 {
     return rxq * 2;
 }
 
 static inline struct virtio_net_hdr_mrg_rxbuf *skb_vnet_hdr(struct sk_buff *skb)
 {
     return (struct virtio_net_hdr_mrg_rxbuf *)skb->cb;
 }
 
 /*
  * 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 receive_queue *rq, struct page *page)
 {
     struct page *end;
 
     /* Find end of list, sew whole thing into vi->rq.pages. */
     for (end = page; end->private; end = (struct page *)end->private);
     end->private = (unsigned long)rq->pages;
     rq->pages = page;
 }
 
 static struct page *get_a_page(struct receive_queue *rq, gfp_t gfp_mask)
 {
     struct page *p = rq->pages;
 
     if (p) {
         rq->pages = (struct page *)p->private;
         /* clear private here, it is used to chain pages */
         p->private = 0;
     } else
         p = alloc_page(gfp_mask);
     return p;
 }
 
 static void enable_delayed_refill(struct virtnet_info *vi)
 {
     spin_lock_bh(&vi->refill_lock);
     vi->refill_enabled = true;
     spin_unlock_bh(&vi->refill_lock);
 }
 
 static void disable_delayed_refill(struct virtnet_info *vi)
 {
     spin_lock_bh(&vi->refill_lock);
     vi->refill_enabled = false;
     spin_unlock_bh(&vi->refill_lock);
 }
 
 static void virtqueue_napi_schedule(struct napi_struct *napi,
                     struct virtqueue *vq)
 {
     if (napi_schedule_prep(napi)) {
         virtqueue_disable_cb(vq);
         __napi_schedule(napi);
     }
 }
 
 static void virtqueue_napi_complete(struct napi_struct *napi,
                     struct virtqueue *vq, int processed)
 {
     int opaque;
 
     opaque = virtqueue_enable_cb_prepare(vq);
     if (napi_complete_done(napi, processed)) {
         if (unlikely(virtqueue_poll(vq, opaque)))
             virtqueue_napi_schedule(napi, vq);
     } else {
         virtqueue_disable_cb(vq);
     }
 }
 
 static void skb_xmit_done(struct virtqueue *vq)
 {
     struct virtnet_info *vi = vq->vdev->priv;
     struct napi_struct *napi = &vi->sq[vq2txq(vq)].napi;
 
     /* Suppress further interrupts. */
     virtqueue_disable_cb(vq);
 
     if (napi->weight)
         virtqueue_napi_schedule(napi, vq);
     else
         /* We were probably waiting for more output buffers. */
         netif_wake_subqueue(vi->dev, vq2txq(vq));
 }
 
 #define MRG_CTX_HEADER_SHIFT 22
 static void *mergeable_len_to_ctx(unsigned int truesize,
                   unsigned int headroom)
 {
     return (void *)(unsigned long)((headroom << MRG_CTX_HEADER_SHIFT) | truesize);
 }
 
 static unsigned int mergeable_ctx_to_headroom(void *mrg_ctx)
 {
     return (unsigned long)mrg_ctx >> MRG_CTX_HEADER_SHIFT;
 }
 
 static unsigned int mergeable_ctx_to_truesize(void *mrg_ctx)
 {
     return (unsigned long)mrg_ctx & ((1 << MRG_CTX_HEADER_SHIFT) - 1);
 }
 
 /* Called from bottom half context */
 static struct sk_buff *page_to_skb(struct virtnet_info *vi,
                    struct receive_queue *rq,
                    struct page *page, unsigned int offset,
                    unsigned int len, unsigned int truesize,
                    bool hdr_valid, unsigned int metasize,
                    unsigned int headroom)
 {
     struct sk_buff *skb;
     struct virtio_net_hdr_mrg_rxbuf *hdr;
     unsigned int copy, hdr_len, hdr_padded_len;
     struct page *page_to_free = NULL;
     int tailroom, shinfo_size;
     char *p, *hdr_p, *buf;
 
     p = page_address(page) + offset;
     hdr_p = p;
 
     hdr_len = vi->hdr_len;
     if (vi->mergeable_rx_bufs)
         hdr_padded_len = hdr_len;
     else
         hdr_padded_len = sizeof(struct padded_vnet_hdr);
 
     /* If headroom is not 0, there is an offset between the beginning of the
      * data and the allocated space, otherwise the data and the allocated
      * space are aligned.
      *
      * Buffers with headroom use PAGE_SIZE as alloc size, see
      * add_recvbuf_mergeable() + get_mergeable_buf_len()
      */
     truesize = headroom ? PAGE_SIZE : truesize;
     tailroom = truesize - headroom;
     buf = p - headroom;
 
     len -= hdr_len;
     offset += hdr_padded_len;
     p += hdr_padded_len;
     tailroom -= hdr_padded_len + len;
 
     shinfo_size = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 
     /* copy small packet so we can reuse these pages */
     if (!NET_IP_ALIGN && len > GOOD_COPY_LEN && tailroom >= shinfo_size) {
         skb = build_skb(buf, truesize);
         if (unlikely(!skb))
             return NULL;
 
         skb_reserve(skb, p - buf);
         skb_put(skb, len);
 
         page = (struct page *)page->private;
         if (page)
             give_pages(rq, page);
         goto ok;
     }
 
     /* copy small packet so we can reuse these pages for small data */
     skb = napi_alloc_skb(&rq->napi, GOOD_COPY_LEN);
     if (unlikely(!skb))
         return NULL;
 
     /* Copy all frame if it fits skb->head, otherwise
      * we let virtio_net_hdr_to_skb() and GRO pull headers as needed.
      */
     if (len <= skb_tailroom(skb))
         copy = len;
     else
         copy = ETH_HLEN + metasize;
     skb_put_data(skb, p, copy);
 
     len -= copy;
     offset += copy;
 
     if (vi->mergeable_rx_bufs) {
         if (len)
             skb_add_rx_frag(skb, 0, page, offset, len, truesize);
         else
             page_to_free = page;
         goto ok;
     }
 
     /*
      * Verify that we can indeed put this data into a skb.
      * This is here to handle cases when the device erroneously
      * tries to receive more than is possible. This is usually
      * the case of a broken device.
      */
     if (unlikely(len > MAX_SKB_FRAGS * PAGE_SIZE)) {
         net_dbg_ratelimited("%s: too much data\n", skb->dev->name);
         dev_kfree_skb(skb);
         return NULL;
     }
     BUG_ON(offset >= PAGE_SIZE);
     while (len) {
         unsigned int frag_size = min((unsigned)PAGE_SIZE - offset, len);
         skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page, offset,
                 frag_size, truesize);
         len -= frag_size;
         page = (struct page *)page->private;
         offset = 0;
     }
 
     if (page)
         give_pages(rq, page);
 
 ok:
     /* hdr_valid means no XDP, so we can copy the vnet header */
     if (hdr_valid) {
         hdr = skb_vnet_hdr(skb);
         memcpy(hdr, hdr_p, hdr_len);
     }
     if (page_to_free)
         put_page(page_to_free);
 
     if (metasize) {
         __skb_pull(skb, metasize);
         skb_metadata_set(skb, metasize);
     }
 
     return skb;
 }
 
 static int __virtnet_xdp_xmit_one(struct virtnet_info *vi,
                    struct send_queue *sq,
                    struct xdp_frame *xdpf)
 {
     struct virtio_net_hdr_mrg_rxbuf *hdr;
     int err;
 
     if (unlikely(xdpf->headroom < vi->hdr_len))
         return -EOVERFLOW;
 
     /* Make room for virtqueue hdr (also change xdpf->headroom?) */
     xdpf->data -= vi->hdr_len;
     /* Zero header and leave csum up to XDP layers */
     hdr = xdpf->data;
     memset(hdr, 0, vi->hdr_len);
     xdpf->len   += vi->hdr_len;
 
     sg_init_one(sq->sg, xdpf->data, xdpf->len);
 
     err = virtqueue_add_outbuf(sq->vq, sq->sg, 1, xdp_to_ptr(xdpf),
                    GFP_ATOMIC);
     if (unlikely(err))
         return -ENOSPC; /* Caller handle free/refcnt */
 
     return 0;
 }
 
 /* when vi->curr_queue_pairs > nr_cpu_ids, the txq/sq is only used for xdp tx on
  * the current cpu, so it does not need to be locked.
  *
  * Here we use marco instead of inline functions because we have to deal with
  * three issues at the same time: 1. the choice of sq. 2. judge and execute the
  * lock/unlock of txq 3. make sparse happy. It is difficult for two inline
  * functions to perfectly solve these three problems at the same time.
  */
 #define virtnet_xdp_get_sq(vi) ({                                       \
     int cpu = smp_processor_id();                                   \
     struct netdev_queue *txq;                                       \
     typeof(vi) v = (vi);                                            \
     unsigned int qp;                                                \
                                     \
     if (v->curr_queue_pairs > nr_cpu_ids) {                         \
         qp = v->curr_queue_pairs - v->xdp_queue_pairs;          \
         qp += cpu;                                              \
         txq = netdev_get_tx_queue(v->dev, qp);                  \
         __netif_tx_acquire(txq);                                \
     } else {                                                        \
         qp = cpu % v->curr_queue_pairs;                         \
         txq = netdev_get_tx_queue(v->dev, qp);                  \
         __netif_tx_lock(txq, cpu);                              \
     }                                                               \
     v->sq + qp;                                                     \
 })
 
 #define virtnet_xdp_put_sq(vi, q) {                                     \
     struct netdev_queue *txq;                                       \
     typeof(vi) v = (vi);                                            \
                                     \
     txq = netdev_get_tx_queue(v->dev, (q) - v->sq);                 \
     if (v->curr_queue_pairs > nr_cpu_ids)                           \
         __netif_tx_release(txq);                                \
     else                                                            \
         __netif_tx_unlock(txq);                                 \
 }
 
 static int virtnet_xdp_xmit(struct net_device *dev,
                 int n, struct xdp_frame **frames, u32 flags)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     struct receive_queue *rq = vi->rq;
     struct bpf_prog *xdp_prog;
     struct send_queue *sq;
     unsigned int len;
     int packets = 0;
     int bytes = 0;
     int nxmit = 0;
     int kicks = 0;
     void *ptr;
     int ret;
     int i;
 
     /* Only allow ndo_xdp_xmit if XDP is loaded on dev, as this
      * indicate XDP resources have been successfully allocated.
      */
     xdp_prog = rcu_access_pointer(rq->xdp_prog);
     if (!xdp_prog)
         return -ENXIO;
 
     sq = virtnet_xdp_get_sq(vi);
 
     if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK)) {
         ret = -EINVAL;
         goto out;
     }
 
     /* Free up any pending old buffers before queueing new ones. */
     while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
         if (likely(is_xdp_frame(ptr))) {
             struct xdp_frame *frame = ptr_to_xdp(ptr);
 
             bytes += frame->len;
             xdp_return_frame(frame);
         } else {
             struct sk_buff *skb = ptr;
 
             bytes += skb->len;
             napi_consume_skb(skb, false);
         }
         packets++;
     }
 
     for (i = 0; i < n; i++) {
         struct xdp_frame *xdpf = frames[i];
 
         if (__virtnet_xdp_xmit_one(vi, sq, xdpf))
             break;
         nxmit++;
     }
     ret = nxmit;
 
     if (flags & XDP_XMIT_FLUSH) {
         if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq))
             kicks = 1;
     }
 out:
     u64_stats_update_begin(&sq->stats.syncp);
     sq->stats.bytes += bytes;
     sq->stats.packets += packets;
     sq->stats.xdp_tx += n;
     sq->stats.xdp_tx_drops += n - nxmit;
     sq->stats.kicks += kicks;
     u64_stats_update_end(&sq->stats.syncp);
 
     virtnet_xdp_put_sq(vi, sq);
     return ret;
 }
 
 static unsigned int virtnet_get_headroom(struct virtnet_info *vi)
 {
     return vi->xdp_enabled ? VIRTIO_XDP_HEADROOM : 0;
 }
 
 /* We copy the packet for XDP in the following cases:
  *
  * 1) Packet is scattered across multiple rx buffers.
  * 2) Headroom space is insufficient.
  *
  * This is inefficient but it's a temporary condition that
  * we hit right after XDP is enabled and until queue is refilled
  * with large buffers with sufficient headroom - so it should affect
  * at most queue size packets.
  * Afterwards, the conditions to enable
  * XDP should preclude the underlying device from sending packets
  * across multiple buffers (num_buf > 1), and we make sure buffers
  * have enough headroom.
  */
 static struct page *xdp_linearize_page(struct receive_queue *rq,
                        u16 *num_buf,
                        struct page *p,
                        int offset,
                        int page_off,
                        unsigned int *len)
 {
     struct page *page = alloc_page(GFP_ATOMIC);
 
     if (!page)
         return NULL;
 
     memcpy(page_address(page) + page_off, page_address(p) + offset, *len);
     page_off += *len;
 
     while (--*num_buf) {
         int tailroom = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
         unsigned int buflen;
         void *buf;
         int off;
 
         buf = virtqueue_get_buf(rq->vq, &buflen);
         if (unlikely(!buf))
             goto err_buf;
 
         p = virt_to_head_page(buf);
         off = buf - page_address(p);
 
         /* guard against a misconfigured or uncooperative backend that
          * is sending packet larger than the MTU.
          */
         if ((page_off + buflen + tailroom) > PAGE_SIZE) {
             put_page(p);
             goto err_buf;
         }
 
         memcpy(page_address(page) + page_off,
                page_address(p) + off, buflen);
         page_off += buflen;
         put_page(p);
     }
 
     /* Headroom does not contribute to packet length */
     *len = page_off - VIRTIO_XDP_HEADROOM;
     return page;
 err_buf:
     __free_pages(page, 0);
     return NULL;
 }
 
 static struct sk_buff *receive_small(struct net_device *dev,
                      struct virtnet_info *vi,
                      struct receive_queue *rq,
                      void *buf, void *ctx,
                      unsigned int len,
                      unsigned int *xdp_xmit,
                      struct virtnet_rq_stats *stats)
 {
     struct sk_buff *skb;
     struct bpf_prog *xdp_prog;
     unsigned int xdp_headroom = (unsigned long)ctx;
     unsigned int header_offset = VIRTNET_RX_PAD + xdp_headroom;
     unsigned int headroom = vi->hdr_len + header_offset;
     unsigned int buflen = SKB_DATA_ALIGN(GOOD_PACKET_LEN + headroom) +
                   SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
     struct page *page = virt_to_head_page(buf);
     unsigned int delta = 0;
     struct page *xdp_page;
     int err;
     unsigned int metasize = 0;
 
     len -= vi->hdr_len;
     stats->bytes += len;
 
     if (unlikely(len > GOOD_PACKET_LEN)) {
         pr_debug("%s: rx error: len %u exceeds max size %d\n",
              dev->name, len, GOOD_PACKET_LEN);
         dev->stats.rx_length_errors++;
         goto err;
     }
 
     if (likely(!vi->xdp_enabled)) {
         xdp_prog = NULL;
         goto skip_xdp;
     }
 
     rcu_read_lock();
     xdp_prog = rcu_dereference(rq->xdp_prog);
     if (xdp_prog) {
         struct virtio_net_hdr_mrg_rxbuf *hdr = buf + header_offset;
         struct xdp_frame *xdpf;
         struct xdp_buff xdp;
         void *orig_data;
         u32 act;
 
         if (unlikely(hdr->hdr.gso_type))
             goto err_xdp;
 
         if (unlikely(xdp_headroom < virtnet_get_headroom(vi))) {
             int offset = buf - page_address(page) + header_offset;
             unsigned int tlen = len + vi->hdr_len;
             u16 num_buf = 1;
 
             xdp_headroom = virtnet_get_headroom(vi);
             header_offset = VIRTNET_RX_PAD + xdp_headroom;
             headroom = vi->hdr_len + header_offset;
             buflen = SKB_DATA_ALIGN(GOOD_PACKET_LEN + headroom) +
                  SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
             xdp_page = xdp_linearize_page(rq, &num_buf, page,
                               offset, header_offset,
                               &tlen);
             if (!xdp_page)
                 goto err_xdp;
 
             buf = page_address(xdp_page);
             put_page(page);
             page = xdp_page;
         }
 
         xdp_init_buff(&xdp, buflen, &rq->xdp_rxq);
         xdp_prepare_buff(&xdp, buf + VIRTNET_RX_PAD + vi->hdr_len,
                  xdp_headroom, len, true);
         orig_data = xdp.data;
         act = bpf_prog_run_xdp(xdp_prog, &xdp);
         stats->xdp_packets++;
 
         switch (act) {
         case XDP_PASS:
             /* Recalculate length in case bpf program changed it */
             delta = orig_data - xdp.data;
             len = xdp.data_end - xdp.data;
             metasize = xdp.data - xdp.data_meta;
             break;
         case XDP_TX:
             stats->xdp_tx++;
             xdpf = xdp_convert_buff_to_frame(&xdp);
             if (unlikely(!xdpf))
                 goto err_xdp;
             err = virtnet_xdp_xmit(dev, 1, &xdpf, 0);
             if (unlikely(!err)) {
                 xdp_return_frame_rx_napi(xdpf);
             } else if (unlikely(err < 0)) {
                 trace_xdp_exception(vi->dev, xdp_prog, act);
                 goto err_xdp;
             }
             *xdp_xmit |= VIRTIO_XDP_TX;
             rcu_read_unlock();
             goto xdp_xmit;
         case XDP_REDIRECT:
             stats->xdp_redirects++;
             err = xdp_do_redirect(dev, &xdp, xdp_prog);
             if (err)
                 goto err_xdp;
             *xdp_xmit |= VIRTIO_XDP_REDIR;
             rcu_read_unlock();
             goto xdp_xmit;
         default:
             bpf_warn_invalid_xdp_action(vi->dev, xdp_prog, act);
             fallthrough;
         case XDP_ABORTED:
             trace_xdp_exception(vi->dev, xdp_prog, act);
             goto err_xdp;
         case XDP_DROP:
             goto err_xdp;
         }
     }
     rcu_read_unlock();
 
 skip_xdp:
     skb = build_skb(buf, buflen);
     if (!skb)
         goto err;
     skb_reserve(skb, headroom - delta);
     skb_put(skb, len);
     if (!xdp_prog) {
         buf += header_offset;
         memcpy(skb_vnet_hdr(skb), buf, vi->hdr_len);
     } /* keep zeroed vnet hdr since XDP is loaded */
 
     if (metasize)
         skb_metadata_set(skb, metasize);
 
     return skb;
 
 err_xdp:
     rcu_read_unlock();
     stats->xdp_drops++;
 err:
     stats->drops++;
     put_page(page);
 xdp_xmit:
     return NULL;
 }
 
 static struct sk_buff *receive_big(struct net_device *dev,
                    struct virtnet_info *vi,
                    struct receive_queue *rq,
                    void *buf,
                    unsigned int len,
                    struct virtnet_rq_stats *stats)
 {
     struct page *page = buf;
     struct sk_buff *skb =
         page_to_skb(vi, rq, page, 0, len, PAGE_SIZE, true, 0, 0);
 
     stats->bytes += len - vi->hdr_len;
     if (unlikely(!skb))
         goto err;
 
     return skb;
 
 err:
     stats->drops++;
     give_pages(rq, page);
     return NULL;
 }
 
 static struct sk_buff *receive_mergeable(struct net_device *dev,
                      struct virtnet_info *vi,
                      struct receive_queue *rq,
                      void *buf,
                      void *ctx,
                      unsigned int len,
                      unsigned int *xdp_xmit,
                      struct virtnet_rq_stats *stats)
 {
     struct virtio_net_hdr_mrg_rxbuf *hdr = buf;
     u16 num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers);
     struct page *page = virt_to_head_page(buf);
     int offset = buf - page_address(page);
     struct sk_buff *head_skb, *curr_skb;
     struct bpf_prog *xdp_prog;
     unsigned int truesize = mergeable_ctx_to_truesize(ctx);
     unsigned int headroom = mergeable_ctx_to_headroom(ctx);
     unsigned int metasize = 0;
     unsigned int frame_sz;
     int err;
 
     head_skb = NULL;
     stats->bytes += len - vi->hdr_len;
 
     if (unlikely(len > truesize)) {
         pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
              dev->name, len, (unsigned long)ctx);
         dev->stats.rx_length_errors++;
         goto err_skb;
     }
 
     if (likely(!vi->xdp_enabled)) {
         xdp_prog = NULL;
         goto skip_xdp;
     }
 
     rcu_read_lock();
     xdp_prog = rcu_dereference(rq->xdp_prog);
     if (xdp_prog) {
         struct xdp_frame *xdpf;
         struct page *xdp_page;
         struct xdp_buff xdp;
         void *data;
         u32 act;
 
         /* Transient failure which in theory could occur if
          * in-flight packets from before XDP was enabled reach
          * the receive path after XDP is loaded.
          */
         if (unlikely(hdr->hdr.gso_type))
             goto err_xdp;
 
         /* Buffers with headroom use PAGE_SIZE as alloc size,
          * see add_recvbuf_mergeable() + get_mergeable_buf_len()
          */
         frame_sz = headroom ? PAGE_SIZE : truesize;
 
         /* This happens when rx buffer size is underestimated
          * or headroom is not enough because of the buffer
          * was refilled before XDP is set. This should only
          * happen for the first several packets, so we don't
          * care much about its performance.
          */
         if (unlikely(num_buf > 1 ||
                  headroom < virtnet_get_headroom(vi))) {
             /* linearize data for XDP */
             xdp_page = xdp_linearize_page(rq, &num_buf,
                               page, offset,
                               VIRTIO_XDP_HEADROOM,
                               &len);
             frame_sz = PAGE_SIZE;
 
             if (!xdp_page)
                 goto err_xdp;
             offset = VIRTIO_XDP_HEADROOM;
         } else {
             xdp_page = page;
         }
 
         /* Allow consuming headroom but reserve enough space to push
          * the descriptor on if we get an XDP_TX return code.
          */
         data = page_address(xdp_page) + offset;
         xdp_init_buff(&xdp, frame_sz - vi->hdr_len, &rq->xdp_rxq);
         xdp_prepare_buff(&xdp, data - VIRTIO_XDP_HEADROOM + vi->hdr_len,
                  VIRTIO_XDP_HEADROOM, len - vi->hdr_len, true);
 
         act = bpf_prog_run_xdp(xdp_prog, &xdp);
         stats->xdp_packets++;
 
         switch (act) {
         case XDP_PASS:
             metasize = xdp.data - xdp.data_meta;
 
             /* recalculate offset to account for any header
              * adjustments and minus the metasize to copy the
              * metadata in page_to_skb(). Note other cases do not
              * build an skb and avoid using offset
              */
             offset = xdp.data - page_address(xdp_page) -
                  vi->hdr_len - metasize;
 
             /* recalculate len if xdp.data, xdp.data_end or
              * xdp.data_meta were adjusted
              */
             len = xdp.data_end - xdp.data + vi->hdr_len + metasize;
 
             /* recalculate headroom if xdp.data or xdp_data_meta
              * were adjusted, note that offset should always point
              * to the start of the reserved bytes for virtio_net
              * header which are followed by xdp.data, that means
              * that offset is equal to the headroom (when buf is
              * starting at the beginning of the page, otherwise
              * there is a base offset inside the page) but it's used
              * with a different starting point (buf start) than
              * xdp.data (buf start + vnet hdr size). If xdp.data or
              * data_meta were adjusted by the xdp prog then the
              * headroom size has changed and so has the offset, we
              * can use data_hard_start, which points at buf start +
              * vnet hdr size, to calculate the new headroom and use
              * it later to compute buf start in page_to_skb()
              */
             headroom = xdp.data - xdp.data_hard_start - metasize;
 
             /* We can only create skb based on xdp_page. */
             if (unlikely(xdp_page != page)) {
                 rcu_read_unlock();
                 put_page(page);
                 head_skb = page_to_skb(vi, rq, xdp_page, offset,
                                len, PAGE_SIZE, false,
                                metasize,
                                headroom);
                 return head_skb;
             }
             break;
         case XDP_TX:
             stats->xdp_tx++;
             xdpf = xdp_convert_buff_to_frame(&xdp);
             if (unlikely(!xdpf)) {
                 if (unlikely(xdp_page != page))
                     put_page(xdp_page);
                 goto err_xdp;
             }
             err = virtnet_xdp_xmit(dev, 1, &xdpf, 0);
             if (unlikely(!err)) {
                 xdp_return_frame_rx_napi(xdpf);
             } else if (unlikely(err < 0)) {
                 trace_xdp_exception(vi->dev, xdp_prog, act);
                 if (unlikely(xdp_page != page))
                     put_page(xdp_page);
                 goto err_xdp;
             }
             *xdp_xmit |= VIRTIO_XDP_TX;
             if (unlikely(xdp_page != page))
                 put_page(page);
             rcu_read_unlock();
             goto xdp_xmit;
         case XDP_REDIRECT:
             stats->xdp_redirects++;
             err = xdp_do_redirect(dev, &xdp, xdp_prog);
             if (err) {
                 if (unlikely(xdp_page != page))
                     put_page(xdp_page);
                 goto err_xdp;
             }
             *xdp_xmit |= VIRTIO_XDP_REDIR;
             if (unlikely(xdp_page != page))
                 put_page(page);
             rcu_read_unlock();
             goto xdp_xmit;
         default:
             bpf_warn_invalid_xdp_action(vi->dev, xdp_prog, act);
             fallthrough;
         case XDP_ABORTED:
             trace_xdp_exception(vi->dev, xdp_prog, act);
             fallthrough;
         case XDP_DROP:
             if (unlikely(xdp_page != page))
                 __free_pages(xdp_page, 0);
             goto err_xdp;
         }
     }
     rcu_read_unlock();
 
 skip_xdp:
     head_skb = page_to_skb(vi, rq, page, offset, len, truesize, !xdp_prog,
                    metasize, headroom);
     curr_skb = head_skb;
 
     if (unlikely(!curr_skb))
         goto err_skb;
     while (--num_buf) {
         int num_skb_frags;
 
         buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx);
         if (unlikely(!buf)) {
             pr_debug("%s: rx error: %d buffers out of %d missing\n",
                  dev->name, num_buf,
                  virtio16_to_cpu(vi->vdev,
                          hdr->num_buffers));
             dev->stats.rx_length_errors++;
             goto err_buf;
         }
 
         stats->bytes += len;
         page = virt_to_head_page(buf);
 
         truesize = mergeable_ctx_to_truesize(ctx);
         if (unlikely(len > truesize)) {
             pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
                  dev->name, len, (unsigned long)ctx);
             dev->stats.rx_length_errors++;
             goto err_skb;
         }
 
         num_skb_frags = skb_shinfo(curr_skb)->nr_frags;
         if (unlikely(num_skb_frags == MAX_SKB_FRAGS)) {
             struct sk_buff *nskb = alloc_skb(0, GFP_ATOMIC);
 
             if (unlikely(!nskb))
                 goto err_skb;
             if (curr_skb == head_skb)
                 skb_shinfo(curr_skb)->frag_list = nskb;
             else
                 curr_skb->next = nskb;
             curr_skb = nskb;
             head_skb->truesize += nskb->truesize;
             num_skb_frags = 0;
         }
         if (curr_skb != head_skb) {
             head_skb->data_len += len;
             head_skb->len += len;
             head_skb->truesize += truesize;
         }
         offset = buf - page_address(page);
         if (skb_can_coalesce(curr_skb, num_skb_frags, page, offset)) {
             put_page(page);
             skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1,
                          len, truesize);
         } else {
             skb_add_rx_frag(curr_skb, num_skb_frags, page,
                     offset, len, truesize);
         }
     }
 
     ewma_pkt_len_add(&rq->mrg_avg_pkt_len, head_skb->len);
     return head_skb;
 
 err_xdp:
     rcu_read_unlock();
     stats->xdp_drops++;
 err_skb:
     put_page(page);
     while (num_buf-- > 1) {
         buf = virtqueue_get_buf(rq->vq, &len);
         if (unlikely(!buf)) {
             pr_debug("%s: rx error: %d buffers missing\n",
                  dev->name, num_buf);
             dev->stats.rx_length_errors++;
             break;
         }
         stats->bytes += len;
         page = virt_to_head_page(buf);
         put_page(page);
     }
 err_buf:
     stats->drops++;
     dev_kfree_skb(head_skb);
 xdp_xmit:
     return NULL;
 }
 
 static void virtio_skb_set_hash(const struct virtio_net_hdr_v1_hash *hdr_hash,
                 struct sk_buff *skb)
 {
     enum pkt_hash_types rss_hash_type;
 
     if (!hdr_hash || !skb)
         return;
 
     switch (__le16_to_cpu(hdr_hash->hash_report)) {
     case VIRTIO_NET_HASH_REPORT_TCPv4:
     case VIRTIO_NET_HASH_REPORT_UDPv4:
     case VIRTIO_NET_HASH_REPORT_TCPv6:
     case VIRTIO_NET_HASH_REPORT_UDPv6:
     case VIRTIO_NET_HASH_REPORT_TCPv6_EX:
     case VIRTIO_NET_HASH_REPORT_UDPv6_EX:
         rss_hash_type = PKT_HASH_TYPE_L4;
         break;
     case VIRTIO_NET_HASH_REPORT_IPv4:
     case VIRTIO_NET_HASH_REPORT_IPv6:
     case VIRTIO_NET_HASH_REPORT_IPv6_EX:
         rss_hash_type = PKT_HASH_TYPE_L3;
         break;
     case VIRTIO_NET_HASH_REPORT_NONE:
     default:
         rss_hash_type = PKT_HASH_TYPE_NONE;
     }
     skb_set_hash(skb, __le32_to_cpu(hdr_hash->hash_value), rss_hash_type);
 }
 
 static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
             void *buf, unsigned int len, void **ctx,
             unsigned int *xdp_xmit,
             struct virtnet_rq_stats *stats)
 {
     struct net_device *dev = vi->dev;
     struct sk_buff *skb;
     struct virtio_net_hdr_mrg_rxbuf *hdr;
 
     if (unlikely(len < vi->hdr_len + ETH_HLEN)) {
         pr_debug("%s: short packet %i\n", dev->name, len);
         dev->stats.rx_length_errors++;
         if (vi->mergeable_rx_bufs) {
             put_page(virt_to_head_page(buf));
         } else if (vi->big_packets) {
             give_pages(rq, buf);
         } else {
             put_page(virt_to_head_page(buf));
         }
         return;
     }
 
     if (vi->mergeable_rx_bufs)
         skb = receive_mergeable(dev, vi, rq, buf, ctx, len, xdp_xmit,
                     stats);
     else if (vi->big_packets)
         skb = receive_big(dev, vi, rq, buf, len, stats);
     else
         skb = receive_small(dev, vi, rq, buf, ctx, len, xdp_xmit, stats);
 
     if (unlikely(!skb))
         return;
 
     hdr = skb_vnet_hdr(skb);
     if (dev->features & NETIF_F_RXHASH && vi->has_rss_hash_report)
         virtio_skb_set_hash((const struct virtio_net_hdr_v1_hash *)hdr, skb);
 
     if (hdr->hdr.flags & VIRTIO_NET_HDR_F_DATA_VALID)
         skb->ip_summed = CHECKSUM_UNNECESSARY;
 
     if (virtio_net_hdr_to_skb(skb, &hdr->hdr,
                   virtio_is_little_endian(vi->vdev))) {
         net_warn_ratelimited("%s: bad gso: type: %u, size: %u\n",
                      dev->name, hdr->hdr.gso_type,
                      hdr->hdr.gso_size);
         goto frame_err;
     }
 
     skb_record_rx_queue(skb, vq2rxq(rq->vq));
     skb->protocol = eth_type_trans(skb, dev);
     pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
          ntohs(skb->protocol), skb->len, skb->pkt_type);
 
     napi_gro_receive(&rq->napi, skb);
     return;
 
 frame_err:
     dev->stats.rx_frame_errors++;
     dev_kfree_skb(skb);
 }
 
 /* Unlike mergeable buffers, all buffers are allocated to the
  * same size, except for the headroom. For this reason we do
  * not need to use  mergeable_len_to_ctx here - it is enough
  * to store the headroom as the context ignoring the truesize.
  */
 static int add_recvbuf_small(struct virtnet_info *vi, struct receive_queue *rq,
                  gfp_t gfp)
 {
     struct page_frag *alloc_frag = &rq->alloc_frag;
     char *buf;
     unsigned int xdp_headroom = virtnet_get_headroom(vi);
     void *ctx = (void *)(unsigned long)xdp_headroom;
     int len = vi->hdr_len + VIRTNET_RX_PAD + GOOD_PACKET_LEN + xdp_headroom;
     int err;
 
     len = SKB_DATA_ALIGN(len) +
           SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
     if (unlikely(!skb_page_frag_refill(len, alloc_frag, gfp)))
         return -ENOMEM;
 
     buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;
     get_page(alloc_frag->page);
     alloc_frag->offset += len;
     sg_init_one(rq->sg, buf + VIRTNET_RX_PAD + xdp_headroom,
             vi->hdr_len + GOOD_PACKET_LEN);
     err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
     if (err < 0)
         put_page(virt_to_head_page(buf));
     return err;
 }
 
 static int add_recvbuf_big(struct virtnet_info *vi, struct receive_queue *rq,
                gfp_t gfp)
 {
     struct page *first, *list = NULL;
     char *p;
     int i, err, offset;
 
     sg_init_table(rq->sg, MAX_SKB_FRAGS + 2);
 
     /* page in rq->sg[MAX_SKB_FRAGS + 1] is list tail */
     for (i = MAX_SKB_FRAGS + 1; i > 1; --i) {
         first = get_a_page(rq, gfp);
         if (!first) {
             if (list)
                 give_pages(rq, list);
             return -ENOMEM;
         }
         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(rq, gfp);
     if (!first) {
         give_pages(rq, list);
         return -ENOMEM;
     }
     p = page_address(first);
 
     /* rq->sg[0], rq->sg[1] share the same page */
     /* a separated rq->sg[0] for header - required in case !any_header_sg */
     sg_set_buf(&rq->sg[0], p, vi->hdr_len);
 
     /* rq->sg[1] for data packet, from offset */
     offset = sizeof(struct padded_vnet_hdr);
     sg_set_buf(&rq->sg[1], p + offset, PAGE_SIZE - offset);
 
     /* chain first in list head */
     first->private = (unsigned long)list;
     err = virtqueue_add_inbuf(rq->vq, rq->sg, MAX_SKB_FRAGS + 2,
                   first, gfp);
     if (err < 0)
         give_pages(rq, first);
 
     return err;
 }
 
 static unsigned int get_mergeable_buf_len(struct receive_queue *rq,
                       struct ewma_pkt_len *avg_pkt_len,
                       unsigned int room)
 {
     struct virtnet_info *vi = rq->vq->vdev->priv;
     const size_t hdr_len = vi->hdr_len;
     unsigned int len;
 
     if (room)
         return PAGE_SIZE - room;
 
     len = hdr_len + clamp_t(unsigned int, ewma_pkt_len_read(avg_pkt_len),
                 rq->min_buf_len, PAGE_SIZE - hdr_len);
 
     return ALIGN(len, L1_CACHE_BYTES);
 }
 
 static int add_recvbuf_mergeable(struct virtnet_info *vi,
                  struct receive_queue *rq, gfp_t gfp)
 {
     struct page_frag *alloc_frag = &rq->alloc_frag;
     unsigned int headroom = virtnet_get_headroom(vi);
     unsigned int tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
     unsigned int room = SKB_DATA_ALIGN(headroom + tailroom);
     char *buf;
     void *ctx;
     int err;
     unsigned int len, hole;
 
     /* Extra tailroom is needed to satisfy XDP's assumption. This
      * means rx frags coalescing won't work, but consider we've
      * disabled GSO for XDP, it won't be a big issue.
      */
     len = get_mergeable_buf_len(rq, &rq->mrg_avg_pkt_len, room);
     if (unlikely(!skb_page_frag_refill(len + room, alloc_frag, gfp)))
         return -ENOMEM;
 
     buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;
     buf += headroom; /* advance address leaving hole at front of pkt */
     get_page(alloc_frag->page);
     alloc_frag->offset += len + room;
     hole = alloc_frag->size - alloc_frag->offset;
     if (hole < len + room) {
         /* To avoid internal fragmentation, if there is very likely not
          * enough space for another buffer, add the remaining space to
          * the current buffer.
          */
         len += hole;
         alloc_frag->offset += hole;
     }
 
     sg_init_one(rq->sg, buf, len);
     ctx = mergeable_len_to_ctx(len, headroom);
     err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
     if (err < 0)
         put_page(virt_to_head_page(buf));
 
     return err;
 }
 
 /*
  * Returns false if we couldn't fill entirely (OOM).
  *
  * Normally run in the receive path, but can also be run from ndo_open
  * 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, struct receive_queue *rq,
               gfp_t gfp)
 {
     int err;
     bool oom;
 
     do {
         if (vi->mergeable_rx_bufs)
             err = add_recvbuf_mergeable(vi, rq, gfp);
         else if (vi->big_packets)
             err = add_recvbuf_big(vi, rq, gfp);
         else
             err = add_recvbuf_small(vi, rq, gfp);
 
         oom = err == -ENOMEM;
         if (err)
             break;
     } while (rq->vq->num_free);
     if (virtqueue_kick_prepare(rq->vq) && virtqueue_notify(rq->vq)) {
         unsigned long flags;
 
         flags = u64_stats_update_begin_irqsave(&rq->stats.syncp);
         rq->stats.kicks++;
         u64_stats_update_end_irqrestore(&rq->stats.syncp, flags);
     }
 
     return !oom;
 }
 
 static void skb_recv_done(struct virtqueue *rvq)
 {
     struct virtnet_info *vi = rvq->vdev->priv;
     struct receive_queue *rq = &vi->rq[vq2rxq(rvq)];
 
     virtqueue_napi_schedule(&rq->napi, rvq);
 }
 
 static void virtnet_napi_enable(struct virtqueue *vq, struct napi_struct *napi)
 {
     napi_enable(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.
      * Call local_bh_enable after to trigger softIRQ processing.
      */
     local_bh_disable();
     virtqueue_napi_schedule(napi, vq);
     local_bh_enable();
 }
 
 static void virtnet_napi_tx_enable(struct virtnet_info *vi,
                    struct virtqueue *vq,
                    struct napi_struct *napi)
 {
     if (!napi->weight)
         return;
 
     /* Tx napi touches cachelines on the cpu handling tx interrupts. Only
      * enable the feature if this is likely affine with the transmit path.
      */
     if (!vi->affinity_hint_set) {
         napi->weight = 0;
         return;
     }
 
     return virtnet_napi_enable(vq, napi);
 }
 
 static void virtnet_napi_tx_disable(struct napi_struct *napi)
 {
     if (napi->weight)
         napi_disable(napi);
 }
 
 static void refill_work(struct work_struct *work)
 {
     struct virtnet_info *vi =
         container_of(work, struct virtnet_info, refill.work);
     bool still_empty;
     int i;
 
     for (i = 0; i < vi->curr_queue_pairs; i++) {
         struct receive_queue *rq = &vi->rq[i];
 
         napi_disable(&rq->napi);
         still_empty = !try_fill_recv(vi, rq, GFP_KERNEL);
         virtnet_napi_enable(rq->vq, &rq->napi);
 
         /* In theory, this can happen: if we don't get any buffers in
          * we will *never* try to fill again.
          */
         if (still_empty)
             schedule_delayed_work(&vi->refill, HZ/2);
     }
 }
 
 static int virtnet_receive(struct receive_queue *rq, int budget,
                unsigned int *xdp_xmit)
 {
     struct virtnet_info *vi = rq->vq->vdev->priv;
     struct virtnet_rq_stats stats = {};
     unsigned int len;
     void *buf;
     int i;
 
     if (!vi->big_packets || vi->mergeable_rx_bufs) {
         void *ctx;
 
         while (stats.packets < budget &&
                (buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx))) {
             receive_buf(vi, rq, buf, len, ctx, xdp_xmit, &stats);
             stats.packets++;
         }
     } else {
         while (stats.packets < budget &&
                (buf = virtqueue_get_buf(rq->vq, &len)) != NULL) {
             receive_buf(vi, rq, buf, len, NULL, xdp_xmit, &stats);
             stats.packets++;
         }
     }
 
     if (rq->vq->num_free > min((unsigned int)budget, virtqueue_get_vring_size(rq->vq)) / 2) {
         if (!try_fill_recv(vi, rq, GFP_ATOMIC)) {
             spin_lock(&vi->refill_lock);
             if (vi->refill_enabled)
                 schedule_delayed_work(&vi->refill, 0);
             spin_unlock(&vi->refill_lock);
         }
     }
 
     u64_stats_update_begin(&rq->stats.syncp);
     for (i = 0; i < VIRTNET_RQ_STATS_LEN; i++) {
         size_t offset = virtnet_rq_stats_desc[i].offset;
         u64 *item;
 
         item = (u64 *)((u8 *)&rq->stats + offset);
         *item += *(u64 *)((u8 *)&stats + offset);
     }
     u64_stats_update_end(&rq->stats.syncp);
 
     return stats.packets;
 }
 
 static void free_old_xmit_skbs(struct send_queue *sq, bool in_napi)
 {
     unsigned int len;
     unsigned int packets = 0;
     unsigned int bytes = 0;
     void *ptr;
 
     while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
         if (likely(!is_xdp_frame(ptr))) {
             struct sk_buff *skb = ptr;
 
             pr_debug("Sent skb %p\n", skb);
 
             bytes += skb->len;
             napi_consume_skb(skb, in_napi);
         } else {
             struct xdp_frame *frame = ptr_to_xdp(ptr);
 
             bytes += frame->len;
             xdp_return_frame(frame);
         }
         packets++;
     }
 
     /* Avoid overhead when no packets have been processed
      * happens when called speculatively from start_xmit.
      */
     if (!packets)
         return;
 
     u64_stats_update_begin(&sq->stats.syncp);
     sq->stats.bytes += bytes;
     sq->stats.packets += packets;
     u64_stats_update_end(&sq->stats.syncp);
 }
 
 static bool is_xdp_raw_buffer_queue(struct virtnet_info *vi, int q)
 {
     if (q < (vi->curr_queue_pairs - vi->xdp_queue_pairs))
         return false;
     else if (q < vi->curr_queue_pairs)
         return true;
     else
         return false;
 }
 
 static void virtnet_poll_cleantx(struct receive_queue *rq)
 {
     struct virtnet_info *vi = rq->vq->vdev->priv;
     unsigned int index = vq2rxq(rq->vq);
     struct send_queue *sq = &vi->sq[index];
     struct netdev_queue *txq = netdev_get_tx_queue(vi->dev, index);
 
     if (!sq->napi.weight || is_xdp_raw_buffer_queue(vi, index))
         return;
 
     if (__netif_tx_trylock(txq)) {
         if (sq->reset) {
             __netif_tx_unlock(txq);
             return;
         }
 
         do {
             virtqueue_disable_cb(sq->vq);
             free_old_xmit_skbs(sq, true);
         } while (unlikely(!virtqueue_enable_cb_delayed(sq->vq)));
 
         if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS)
             netif_tx_wake_queue(txq);
 
         __netif_tx_unlock(txq);
     }
 }
 
 static int virtnet_poll(struct napi_struct *napi, int budget)
 {
     struct receive_queue *rq =
         container_of(napi, struct receive_queue, napi);
     struct virtnet_info *vi = rq->vq->vdev->priv;
     struct send_queue *sq;
     unsigned int received;
     unsigned int xdp_xmit = 0;
 
     virtnet_poll_cleantx(rq);
 
     received = virtnet_receive(rq, budget, &xdp_xmit);
 
     /* Out of packets? */
     if (received < budget)
         virtqueue_napi_complete(napi, rq->vq, received);
 
     if (xdp_xmit & VIRTIO_XDP_REDIR)
         xdp_do_flush();
 
     if (xdp_xmit & VIRTIO_XDP_TX) {
         sq = virtnet_xdp_get_sq(vi);
         if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {
             u64_stats_update_begin(&sq->stats.syncp);
             sq->stats.kicks++;
             u64_stats_update_end(&sq->stats.syncp);
         }
         virtnet_xdp_put_sq(vi, sq);
     }
 
     return received;
 }
 
 static int virtnet_open(struct net_device *dev)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     int i, err;
 
     enable_delayed_refill(vi);
 
     for (i = 0; i < vi->max_queue_pairs; i++) {
         if (i < vi->curr_queue_pairs)
             /* Make sure we have some buffers: if oom use wq. */
             if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL))
                 schedule_delayed_work(&vi->refill, 0);
 
         err = xdp_rxq_info_reg(&vi->rq[i].xdp_rxq, dev, i, vi->rq[i].napi.napi_id);
         if (err < 0)
             return err;
 
         err = xdp_rxq_info_reg_mem_model(&vi->rq[i].xdp_rxq,
                          MEM_TYPE_PAGE_SHARED, NULL);
         if (err < 0) {
             xdp_rxq_info_unreg(&vi->rq[i].xdp_rxq);
             return err;
         }
 
         virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);
         virtnet_napi_tx_enable(vi, vi->sq[i].vq, &vi->sq[i].napi);
     }
 
     return 0;
 }
 
 static int virtnet_poll_tx(struct napi_struct *napi, int budget)
 {
     struct send_queue *sq = container_of(napi, struct send_queue, napi);
     struct virtnet_info *vi = sq->vq->vdev->priv;
     unsigned int index = vq2txq(sq->vq);
     struct netdev_queue *txq;
     int opaque;
     bool done;
 
     if (unlikely(is_xdp_raw_buffer_queue(vi, index))) {
         /* We don't need to enable cb for XDP */
         napi_complete_done(napi, 0);
         return 0;
     }
 
     txq = netdev_get_tx_queue(vi->dev, index);
     __netif_tx_lock(txq, raw_smp_processor_id());
     virtqueue_disable_cb(sq->vq);
     free_old_xmit_skbs(sq, true);
 
     if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS)
         netif_tx_wake_queue(txq);
 
     opaque = virtqueue_enable_cb_prepare(sq->vq);
 
     done = napi_complete_done(napi, 0);
 
     if (!done)
         virtqueue_disable_cb(sq->vq);
 
     __netif_tx_unlock(txq);
 
     if (done) {
         if (unlikely(virtqueue_poll(sq->vq, opaque))) {
             if (napi_schedule_prep(napi)) {
                 __netif_tx_lock(txq, raw_smp_processor_id());
                 virtqueue_disable_cb(sq->vq);
                 __netif_tx_unlock(txq);
                 __napi_schedule(napi);
             }
         }
     }
 
     return 0;
 }
 
 static int xmit_skb(struct send_queue *sq, struct sk_buff *skb)
 {
     struct virtio_net_hdr_mrg_rxbuf *hdr;
     const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
     struct virtnet_info *vi = sq->vq->vdev->priv;
     int num_sg;
     unsigned hdr_len = vi->hdr_len;
     bool can_push;
 
     pr_debug("%s: xmit %p %pM\n", vi->dev->name, skb, dest);
 
     can_push = vi->any_header_sg &&
         !((unsigned long)skb->data & (__alignof__(*hdr) - 1)) &&
         !skb_header_cloned(skb) && skb_headroom(skb) >= hdr_len;
     /* Even if we can, don't push here yet as this would skew
      * csum_start offset below. */
     if (can_push)
         hdr = (struct virtio_net_hdr_mrg_rxbuf *)(skb->data - hdr_len);
     else
         hdr = skb_vnet_hdr(skb);
 
     if (virtio_net_hdr_from_skb(skb, &hdr->hdr,
                     virtio_is_little_endian(vi->vdev), false,
                     0))
         return -EPROTO;
 
     if (vi->mergeable_rx_bufs)
         hdr->num_buffers = 0;
 
     sg_init_table(sq->sg, skb_shinfo(skb)->nr_frags + (can_push ? 1 : 2));
     if (can_push) {
         __skb_push(skb, hdr_len);
         num_sg = skb_to_sgvec(skb, sq->sg, 0, skb->len);
         if (unlikely(num_sg < 0))
             return num_sg;
         /* Pull header back to avoid skew in tx bytes calculations. */
         __skb_pull(skb, hdr_len);
     } else {
         sg_set_buf(sq->sg, hdr, hdr_len);
         num_sg = skb_to_sgvec(skb, sq->sg + 1, 0, skb->len);
         if (unlikely(num_sg < 0))
             return num_sg;
         num_sg++;
     }
     return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, 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 send_queue *sq = &vi->sq[qnum];
     int err;
     struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum);
     bool kick = !netdev_xmit_more();
     bool use_napi = sq->napi.weight;
 
     /* Free up any pending old buffers before queueing new ones. */
     do {
         if (use_napi)
             virtqueue_disable_cb(sq->vq);
 
         free_old_xmit_skbs(sq, false);
 
     } while (use_napi && kick &&
            unlikely(!virtqueue_enable_cb_delayed(sq->vq)));
 
     /* timestamp packet in software */
     skb_tx_timestamp(skb);
 
     /* Try to transmit */
     err = xmit_skb(sq, skb);
 
     /* This should not happen! */
     if (unlikely(err)) {
         dev->stats.tx_fifo_errors++;
         if (net_ratelimit())
             dev_warn(&dev->dev,
                  "Unexpected TXQ (%d) queue failure: %d\n",
                  qnum, err);
         dev->stats.tx_dropped++;
         dev_kfree_skb_any(skb);
         return NETDEV_TX_OK;
     }
 
     /* Don't wait up for transmitted skbs to be freed. */
     if (!use_napi) {
         skb_orphan(skb);
         nf_reset_ct(skb);
     }
 
     /* If running out of space, stop queue to avoid getting packets that we
      * are then unable to transmit.
      * An alternative would be to force queuing layer to requeue the skb by
      * returning NETDEV_TX_BUSY. However, NETDEV_TX_BUSY should not be
      * returned in a normal path of operation: it means that driver is not
      * maintaining the TX queue stop/start state properly, and causes
      * the stack to do a non-trivial amount of useless work.
      * Since most packets only take 1 or 2 ring slots, stopping the queue
      * early means 16 slots are typically wasted.
      */
     if (sq->vq->num_free < 2+MAX_SKB_FRAGS) {
         netif_stop_subqueue(dev, qnum);
         if (!use_napi &&
             unlikely(!virtqueue_enable_cb_delayed(sq->vq))) {
             /* More just got used, free them then recheck. */
             free_old_xmit_skbs(sq, false);
             if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) {
                 netif_start_subqueue(dev, qnum);
                 virtqueue_disable_cb(sq->vq);
             }
         }
     }
 
     if (kick || netif_xmit_stopped(txq)) {
         if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {
             u64_stats_update_begin(&sq->stats.syncp);
             sq->stats.kicks++;
             u64_stats_update_end(&sq->stats.syncp);
         }
     }
 
     return NETDEV_TX_OK;
 }
 
 static int virtnet_rx_resize(struct virtnet_info *vi,
                  struct receive_queue *rq, u32 ring_num)
 {
     bool running = netif_running(vi->dev);
     int err, qindex;
 
     qindex = rq - vi->rq;
 
     if (running)
         napi_disable(&rq->napi);
 
     err = virtqueue_resize(rq->vq, ring_num, virtnet_rq_free_unused_buf);
     if (err)
         netdev_err(vi->dev, "resize rx fail: rx queue index: %d err: %d\n", qindex, err);
 
     if (!try_fill_recv(vi, rq, GFP_KERNEL))
         schedule_delayed_work(&vi->refill, 0);
 
     if (running)
         virtnet_napi_enable(rq->vq, &rq->napi);
     return err;
 }
 
 static int virtnet_tx_resize(struct virtnet_info *vi,
                  struct send_queue *sq, u32 ring_num)
 {
     bool running = netif_running(vi->dev);
     struct netdev_queue *txq;
     int err, qindex;
 
     qindex = sq - vi->sq;
 
     if (running)
         virtnet_napi_tx_disable(&sq->napi);
 
     txq = netdev_get_tx_queue(vi->dev, qindex);
 
     /* 1. wait all ximt complete
      * 2. fix the race of netif_stop_subqueue() vs netif_start_subqueue()
      */
     __netif_tx_lock_bh(txq);
 
     /* Prevent rx poll from accessing sq. */
     sq->reset = true;
 
     /* Prevent the upper layer from trying to send packets. */
     netif_stop_subqueue(vi->dev, qindex);
 
     __netif_tx_unlock_bh(txq);
 
     err = virtqueue_resize(sq->vq, ring_num, virtnet_sq_free_unused_buf);
     if (err)
         netdev_err(vi->dev, "resize tx fail: tx queue index: %d err: %d\n", qindex, err);
 
     __netif_tx_lock_bh(txq);
     sq->reset = false;
     netif_tx_wake_queue(txq);
     __netif_tx_unlock_bh(txq);
 
     if (running)
         virtnet_napi_tx_enable(vi, sq->vq, &sq->napi);
     return err;
 }
 
 /*
  * Send command via the control virtqueue and check status.  Commands
  * supported by the hypervisor, as indicated by feature bits, should
  * never fail unless improperly formatted.
  */
 static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
                  struct scatterlist *out)
 {
     struct scatterlist *sgs[4], hdr, stat;
     unsigned out_num = 0, tmp;
     int ret;
 
     /* Caller should know better */
     BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ));
 
     vi->ctrl->status = ~0;
     vi->ctrl->hdr.class = class;
     vi->ctrl->hdr.cmd = cmd;
     /* Add header */
     sg_init_one(&hdr, &vi->ctrl->hdr, sizeof(vi->ctrl->hdr));
     sgs[out_num++] = &hdr;
 
     if (out)
         sgs[out_num++] = out;
 
     /* Add return status. */
     sg_init_one(&stat, &vi->ctrl->status, sizeof(vi->ctrl->status));
     sgs[out_num] = &stat;
 
     BUG_ON(out_num + 1 > ARRAY_SIZE(sgs));
     ret = virtqueue_add_sgs(vi->cvq, sgs, out_num, 1, vi, GFP_ATOMIC);
     if (ret < 0) {
         dev_warn(&vi->vdev->dev,
              "Failed to add sgs for command vq: %d\n.", ret);
         return false;
     }
 
     if (unlikely(!virtqueue_kick(vi->cvq)))
         return vi->ctrl->status == VIRTIO_NET_OK;
 
     /* Spin for a response, the kick causes an ioport write, trapping
      * into the hypervisor, so the request should be handled immediately.
      */
     while (!virtqueue_get_buf(vi->cvq, &tmp) &&
            !virtqueue_is_broken(vi->cvq))
         cpu_relax();
 
     return vi->ctrl->status == VIRTIO_NET_OK;
 }
 
 static int virtnet_set_mac_address(struct net_device *dev, void *p)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     struct virtio_device *vdev = vi->vdev;
     int ret;
     struct sockaddr *addr;
     struct scatterlist sg;
 
     if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STANDBY))
         return -EOPNOTSUPP;
 
     addr = kmemdup(p, sizeof(*addr), GFP_KERNEL);
     if (!addr)
         return -ENOMEM;
 
     ret = eth_prepare_mac_addr_change(dev, addr);
     if (ret)
         goto out;
 
     if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)) {
         sg_init_one(&sg, addr->sa_data, dev->addr_len);
         if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
                       VIRTIO_NET_CTRL_MAC_ADDR_SET, &sg)) {
             dev_warn(&vdev->dev,
                  "Failed to set mac address by vq command.\n");
             ret = -EINVAL;
             goto out;
         }
     } else if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC) &&
            !virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
         unsigned int i;
 
         /* Naturally, this has an atomicity problem. */
         for (i = 0; i < dev->addr_len; i++)
             virtio_cwrite8(vdev,
                        offsetof(struct virtio_net_config, mac) +
                        i, addr->sa_data[i]);
     }
 
     eth_commit_mac_addr_change(dev, p);
     ret = 0;
 
 out:
     kfree(addr);
     return ret;
 }
 
 static void virtnet_stats(struct net_device *dev,
               struct rtnl_link_stats64 *tot)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     unsigned int start;
     int i;
 
     for (i = 0; i < vi->max_queue_pairs; i++) {
         u64 tpackets, tbytes, terrors, rpackets, rbytes, rdrops;
         struct receive_queue *rq = &vi->rq[i];
         struct send_queue *sq = &vi->sq[i];
 
         do {
             start = u64_stats_fetch_begin_irq(&sq->stats.syncp);
             tpackets = sq->stats.packets;
             tbytes   = sq->stats.bytes;
             terrors  = sq->stats.tx_timeouts;
         } while (u64_stats_fetch_retry_irq(&sq->stats.syncp, start));
 
         do {
             start = u64_stats_fetch_begin_irq(&rq->stats.syncp);
             rpackets = rq->stats.packets;
             rbytes   = rq->stats.bytes;
             rdrops   = rq->stats.drops;
         } while (u64_stats_fetch_retry_irq(&rq->stats.syncp, start));
 
         tot->rx_packets += rpackets;
         tot->tx_packets += tpackets;
         tot->rx_bytes   += rbytes;
         tot->tx_bytes   += tbytes;
         tot->rx_dropped += rdrops;
         tot->tx_errors  += terrors;
     }
 
     tot->tx_dropped = dev->stats.tx_dropped;
     tot->tx_fifo_errors = dev->stats.tx_fifo_errors;
     tot->rx_length_errors = dev->stats.rx_length_errors;
     tot->rx_frame_errors = dev->stats.rx_frame_errors;
 }
 
 static void virtnet_ack_link_announce(struct virtnet_info *vi)
 {
     rtnl_lock();
     if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_ANNOUNCE,
                   VIRTIO_NET_CTRL_ANNOUNCE_ACK, NULL))
         dev_warn(&vi->dev->dev, "Failed to ack link announce.\n");
     rtnl_unlock();
 }
 
 static int _virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs)
 {
     struct scatterlist sg;
     struct net_device *dev = vi->dev;
 
     if (!vi->has_cvq || !virtio_has_feature(vi->vdev, VIRTIO_NET_F_MQ))
         return 0;
 
     vi->ctrl->mq.virtqueue_pairs = cpu_to_virtio16(vi->vdev, queue_pairs);
     sg_init_one(&sg, &vi->ctrl->mq, sizeof(vi->ctrl->mq));
 
     if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MQ,
                   VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET, &sg)) {
         dev_warn(&dev->dev, "Fail to set num of queue pairs to %d\n",
              queue_pairs);
         return -EINVAL;
     } else {
         vi->curr_queue_pairs = queue_pairs;
         /* virtnet_open() will refill when device is going to up. */
         if (dev->flags & IFF_UP)
             schedule_delayed_work(&vi->refill, 0);
     }
 
     return 0;
 }
 
 static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs)
 {
     int err;
 
     rtnl_lock();
     err = _virtnet_set_queues(vi, queue_pairs);
     rtnl_unlock();
     return err;
 }
 
 static int virtnet_close(struct net_device *dev)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     int i;
 
     /* Make sure NAPI doesn't schedule refill work */
     disable_delayed_refill(vi);
     /* Make sure refill_work doesn't re-enable napi! */
     cancel_delayed_work_sync(&vi->refill);
 
     for (i = 0; i < vi->max_queue_pairs; i++) {
         xdp_rxq_info_unreg(&vi->rq[i].xdp_rxq);
         napi_disable(&vi->rq[i].napi);
         virtnet_napi_tx_disable(&vi->sq[i].napi);
     }
 
     return 0;
 }
 
 static void virtnet_set_rx_mode(struct net_device *dev)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     struct scatterlist sg[2];
     struct virtio_net_ctrl_mac *mac_data;
     struct netdev_hw_addr *ha;
     int uc_count;
     int mc_count;
     void *buf;
     int i;
 
     /* We can't dynamically set ndo_set_rx_mode, so return gracefully */
     if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_RX))
         return;
 
     vi->ctrl->promisc = ((dev->flags & IFF_PROMISC) != 0);
     vi->ctrl->allmulti = ((dev->flags & IFF_ALLMULTI) != 0);
 
     sg_init_one(sg, &vi->ctrl->promisc, sizeof(vi->ctrl->promisc));
 
     if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RX,
                   VIRTIO_NET_CTRL_RX_PROMISC, sg))
         dev_warn(&dev->dev, "Failed to %sable promisc mode.\n",
              vi->ctrl->promisc ? "en" : "dis");
 
     sg_init_one(sg, &vi->ctrl->allmulti, sizeof(vi->ctrl->allmulti));
 
     if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RX,
                   VIRTIO_NET_CTRL_RX_ALLMULTI, sg))
         dev_warn(&dev->dev, "Failed to %sable allmulti mode.\n",
              vi->ctrl->allmulti ? "en" : "dis");
 
     uc_count = netdev_uc_count(dev);
     mc_count = netdev_mc_count(dev);
     /* MAC filter - use one buffer for both lists */
     buf = kzalloc(((uc_count + mc_count) * ETH_ALEN) +
               (2 * sizeof(mac_data->entries)), GFP_ATOMIC);
     mac_data = buf;
     if (!buf)
         return;
 
     sg_init_table(sg, 2);
 
     /* Store the unicast list and count in the front of the buffer */
     mac_data->entries = cpu_to_virtio32(vi->vdev, uc_count);
     i = 0;
     netdev_for_each_uc_addr(ha, dev)
         memcpy(&mac_data->macs[i++][0], ha->addr, ETH_ALEN);
 
     sg_set_buf(&sg[0], mac_data,
            sizeof(mac_data->entries) + (uc_count * ETH_ALEN));
 
     /* multicast list and count fill the end */
     mac_data = (void *)&mac_data->macs[uc_count][0];
 
     mac_data->entries = cpu_to_virtio32(vi->vdev, mc_count);
     i = 0;
     netdev_for_each_mc_addr(ha, dev)
         memcpy(&mac_data->macs[i++][0], ha->addr, ETH_ALEN);
 
     sg_set_buf(&sg[1], mac_data,
            sizeof(mac_data->entries) + (mc_count * ETH_ALEN));
 
     if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
                   VIRTIO_NET_CTRL_MAC_TABLE_SET, sg))
         dev_warn(&dev->dev, "Failed to set MAC filter table.\n");
 
     kfree(buf);
 }
 
 static int virtnet_vlan_rx_add_vid(struct net_device *dev,
                    __be16 proto, u16 vid)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     struct scatterlist sg;
 
     vi->ctrl->vid = cpu_to_virtio16(vi->vdev, vid);
     sg_init_one(&sg, &vi->ctrl->vid, sizeof(vi->ctrl->vid));
 
     if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
                   VIRTIO_NET_CTRL_VLAN_ADD, &sg))
         dev_warn(&dev->dev, "Failed to add VLAN ID %d.\n", vid);
     return 0;
 }
 
 static int virtnet_vlan_rx_kill_vid(struct net_device *dev,
                     __be16 proto, u16 vid)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     struct scatterlist sg;
 
     vi->ctrl->vid = cpu_to_virtio16(vi->vdev, vid);
     sg_init_one(&sg, &vi->ctrl->vid, sizeof(vi->ctrl->vid));
 
     if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
                   VIRTIO_NET_CTRL_VLAN_DEL, &sg))
         dev_warn(&dev->dev, "Failed to kill VLAN ID %d.\n", vid);
     return 0;
 }
 
 static void virtnet_clean_affinity(struct virtnet_info *vi)
 {
     int i;
 
     if (vi->affinity_hint_set) {
         for (i = 0; i < vi->max_queue_pairs; i++) {
             virtqueue_set_affinity(vi->rq[i].vq, NULL);
             virtqueue_set_affinity(vi->sq[i].vq, NULL);
         }
 
         vi->affinity_hint_set = false;
     }
 }
 
 static void virtnet_set_affinity(struct virtnet_info *vi)
 {
     cpumask_var_t mask;
     int stragglers;
     int group_size;
     int i, j, cpu;
     int num_cpu;
     int stride;
 
     if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
         virtnet_clean_affinity(vi);
         return;
     }
 
     num_cpu = num_online_cpus();
     stride = max_t(int, num_cpu / vi->curr_queue_pairs, 1);
     stragglers = num_cpu >= vi->curr_queue_pairs ?
             num_cpu % vi->curr_queue_pairs :
             0;
     cpu = cpumask_first(cpu_online_mask);
 
     for (i = 0; i < vi->curr_queue_pairs; i++) {
         group_size = stride + (i < stragglers ? 1 : 0);
 
         for (j = 0; j < group_size; j++) {
             cpumask_set_cpu(cpu, mask);
             cpu = cpumask_next_wrap(cpu, cpu_online_mask,
                         nr_cpu_ids, false);
         }
         virtqueue_set_affinity(vi->rq[i].vq, mask);
         virtqueue_set_affinity(vi->sq[i].vq, mask);
         __netif_set_xps_queue(vi->dev, cpumask_bits(mask), i, XPS_CPUS);
         cpumask_clear(mask);
     }
 
     vi->affinity_hint_set = true;
     free_cpumask_var(mask);
 }
 
 static int virtnet_cpu_online(unsigned int cpu, struct hlist_node *node)
 {
     struct virtnet_info *vi = hlist_entry_safe(node, struct virtnet_info,
                            node);
     virtnet_set_affinity(vi);
     return 0;
 }
 
 static int virtnet_cpu_dead(unsigned int cpu, struct hlist_node *node)
 {
     struct virtnet_info *vi = hlist_entry_safe(node, struct virtnet_info,
                            node_dead);
     virtnet_set_affinity(vi);
     return 0;
 }
 
 static int virtnet_cpu_down_prep(unsigned int cpu, struct hlist_node *node)
 {
     struct virtnet_info *vi = hlist_entry_safe(node, struct virtnet_info,
                            node);
 
     virtnet_clean_affinity(vi);
     return 0;
 }
 
 static enum cpuhp_state virtionet_online;
 
 static int virtnet_cpu_notif_add(struct virtnet_info *vi)
 {
     int ret;
 
     ret = cpuhp_state_add_instance_nocalls(virtionet_online, &vi->node);
     if (ret)
         return ret;
     ret = cpuhp_state_add_instance_nocalls(CPUHP_VIRT_NET_DEAD,
                            &vi->node_dead);
     if (!ret)
         return ret;
     cpuhp_state_remove_instance_nocalls(virtionet_online, &vi->node);
     return ret;
 }
 
 static void virtnet_cpu_notif_remove(struct virtnet_info *vi)
 {
     cpuhp_state_remove_instance_nocalls(virtionet_online, &vi->node);
     cpuhp_state_remove_instance_nocalls(CPUHP_VIRT_NET_DEAD,
                         &vi->node_dead);
 }
 
 static void virtnet_get_ringparam(struct net_device *dev,
                   struct ethtool_ringparam *ring,
                   struct kernel_ethtool_ringparam *kernel_ring,
                   struct netlink_ext_ack *extack)
 {
     struct virtnet_info *vi = netdev_priv(dev);
 
     ring->rx_max_pending = vi->rq[0].vq->num_max;
     ring->tx_max_pending = vi->sq[0].vq->num_max;
     ring->rx_pending = virtqueue_get_vring_size(vi->rq[0].vq);
     ring->tx_pending = virtqueue_get_vring_size(vi->sq[0].vq);
 }
 
 static int virtnet_set_ringparam(struct net_device *dev,
                  struct ethtool_ringparam *ring,
                  struct kernel_ethtool_ringparam *kernel_ring,
                  struct netlink_ext_ack *extack)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     u32 rx_pending, tx_pending;
     struct receive_queue *rq;
     struct send_queue *sq;
     int i, err;
 
     if (ring->rx_mini_pending || ring->rx_jumbo_pending)
         return -EINVAL;
 
     rx_pending = virtqueue_get_vring_size(vi->rq[0].vq);
     tx_pending = virtqueue_get_vring_size(vi->sq[0].vq);
 
     if (ring->rx_pending == rx_pending &&
         ring->tx_pending == tx_pending)
         return 0;
 
     if (ring->rx_pending > vi->rq[0].vq->num_max)
         return -EINVAL;
 
     if (ring->tx_pending > vi->sq[0].vq->num_max)
         return -EINVAL;
 
     for (i = 0; i < vi->max_queue_pairs; i++) {
         rq = vi->rq + i;
         sq = vi->sq + i;
 
         if (ring->tx_pending != tx_pending) {
             err = virtnet_tx_resize(vi, sq, ring->tx_pending);
             if (err)
                 return err;
         }
 
         if (ring->rx_pending != rx_pending) {
             err = virtnet_rx_resize(vi, rq, ring->rx_pending);
             if (err)
                 return err;
         }
     }
 
     return 0;
 }
 
 static bool virtnet_commit_rss_command(struct virtnet_info *vi)
 {
     struct net_device *dev = vi->dev;
     struct scatterlist sgs[4];
     unsigned int sg_buf_size;
 
     /* prepare sgs */
     sg_init_table(sgs, 4);
 
     sg_buf_size = offsetof(struct virtio_net_ctrl_rss, indirection_table);
     sg_set_buf(&sgs[0], &vi->ctrl->rss, sg_buf_size);
 
     sg_buf_size = sizeof(uint16_t) * (vi->ctrl->rss.indirection_table_mask + 1);
     sg_set_buf(&sgs[1], vi->ctrl->rss.indirection_table, sg_buf_size);
 
     sg_buf_size = offsetof(struct virtio_net_ctrl_rss, key)
             - offsetof(struct virtio_net_ctrl_rss, max_tx_vq);
     sg_set_buf(&sgs[2], &vi->ctrl->rss.max_tx_vq, sg_buf_size);
 
     sg_buf_size = vi->rss_key_size;
     sg_set_buf(&sgs[3], vi->ctrl->rss.key, sg_buf_size);
 
     if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MQ,
                   vi->has_rss ? VIRTIO_NET_CTRL_MQ_RSS_CONFIG
                   : VIRTIO_NET_CTRL_MQ_HASH_CONFIG, sgs)) {
         dev_warn(&dev->dev, "VIRTIONET issue with committing RSS sgs\n");
         return false;
     }
     return true;
 }
 
 static void virtnet_init_default_rss(struct virtnet_info *vi)
 {
     u32 indir_val = 0;
     int i = 0;
 
     vi->ctrl->rss.hash_types = vi->rss_hash_types_supported;
     vi->rss_hash_types_saved = vi->rss_hash_types_supported;
     vi->ctrl->rss.indirection_table_mask = vi->rss_indir_table_size
                         ? vi->rss_indir_table_size - 1 : 0;
     vi->ctrl->rss.unclassified_queue = 0;
 
     for (; i < vi->rss_indir_table_size; ++i) {
         indir_val = ethtool_rxfh_indir_default(i, vi->curr_queue_pairs);
         vi->ctrl->rss.indirection_table[i] = indir_val;
     }
 
     vi->ctrl->rss.max_tx_vq = vi->curr_queue_pairs;
     vi->ctrl->rss.hash_key_length = vi->rss_key_size;
 
     netdev_rss_key_fill(vi->ctrl->rss.key, vi->rss_key_size);
 }
 
 static void virtnet_get_hashflow(const struct virtnet_info *vi, struct ethtool_rxnfc *info)
 {
     info->data = 0;
     switch (info->flow_type) {
     case TCP_V4_FLOW:
         if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_TCPv4) {
             info->data = RXH_IP_SRC | RXH_IP_DST |
                          RXH_L4_B_0_1 | RXH_L4_B_2_3;
         } else if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv4) {
             info->data = RXH_IP_SRC | RXH_IP_DST;
         }
         break;
     case TCP_V6_FLOW:
         if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_TCPv6) {
             info->data = RXH_IP_SRC | RXH_IP_DST |
                          RXH_L4_B_0_1 | RXH_L4_B_2_3;
         } else if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv6) {
             info->data = RXH_IP_SRC | RXH_IP_DST;
         }
         break;
     case UDP_V4_FLOW:
         if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_UDPv4) {
             info->data = RXH_IP_SRC | RXH_IP_DST |
                          RXH_L4_B_0_1 | RXH_L4_B_2_3;
         } else if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv4) {
             info->data = RXH_IP_SRC | RXH_IP_DST;
         }
         break;
     case UDP_V6_FLOW:
         if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_UDPv6) {
             info->data = RXH_IP_SRC | RXH_IP_DST |
                          RXH_L4_B_0_1 | RXH_L4_B_2_3;
         } else if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv6) {
             info->data = RXH_IP_SRC | RXH_IP_DST;
         }
         break;
     case IPV4_FLOW:
         if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv4)
             info->data = RXH_IP_SRC | RXH_IP_DST;
 
         break;
     case IPV6_FLOW:
         if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv6)
             info->data = RXH_IP_SRC | RXH_IP_DST;
 
         break;
     default:
         info->data = 0;
         break;
     }
 }
 
 static bool virtnet_set_hashflow(struct virtnet_info *vi, struct ethtool_rxnfc *info)
 {
     u32 new_hashtypes = vi->rss_hash_types_saved;
     bool is_disable = info->data & RXH_DISCARD;
     bool is_l4 = info->data == (RXH_IP_SRC | RXH_IP_DST | RXH_L4_B_0_1 | RXH_L4_B_2_3);
 
     /* supports only 'sd', 'sdfn' and 'r' */
     if (!((info->data == (RXH_IP_SRC | RXH_IP_DST)) | is_l4 | is_disable))
         return false;
 
     switch (info->flow_type) {
     case TCP_V4_FLOW:
         new_hashtypes &= ~(VIRTIO_NET_RSS_HASH_TYPE_IPv4 | VIRTIO_NET_RSS_HASH_TYPE_TCPv4);
         if (!is_disable)
             new_hashtypes |= VIRTIO_NET_RSS_HASH_TYPE_IPv4
                 | (is_l4 ? VIRTIO_NET_RSS_HASH_TYPE_TCPv4 : 0);
         break;
     case UDP_V4_FLOW:
         new_hashtypes &= ~(VIRTIO_NET_RSS_HASH_TYPE_IPv4 | VIRTIO_NET_RSS_HASH_TYPE_UDPv4);
         if (!is_disable)
             new_hashtypes |= VIRTIO_NET_RSS_HASH_TYPE_IPv4
                 | (is_l4 ? VIRTIO_NET_RSS_HASH_TYPE_UDPv4 : 0);
         break;
     case IPV4_FLOW:
         new_hashtypes &= ~VIRTIO_NET_RSS_HASH_TYPE_IPv4;
         if (!is_disable)
             new_hashtypes = VIRTIO_NET_RSS_HASH_TYPE_IPv4;
         break;
     case TCP_V6_FLOW:
         new_hashtypes &= ~(VIRTIO_NET_RSS_HASH_TYPE_IPv6 | VIRTIO_NET_RSS_HASH_TYPE_TCPv6);
         if (!is_disable)
             new_hashtypes |= VIRTIO_NET_RSS_HASH_TYPE_IPv6
                 | (is_l4 ? VIRTIO_NET_RSS_HASH_TYPE_TCPv6 : 0);
         break;
     case UDP_V6_FLOW:
         new_hashtypes &= ~(VIRTIO_NET_RSS_HASH_TYPE_IPv6 | VIRTIO_NET_RSS_HASH_TYPE_UDPv6);
         if (!is_disable)
             new_hashtypes |= VIRTIO_NET_RSS_HASH_TYPE_IPv6
                 | (is_l4 ? VIRTIO_NET_RSS_HASH_TYPE_UDPv6 : 0);
         break;
     case IPV6_FLOW:
         new_hashtypes &= ~VIRTIO_NET_RSS_HASH_TYPE_IPv6;
         if (!is_disable)
             new_hashtypes = VIRTIO_NET_RSS_HASH_TYPE_IPv6;
         break;
     default:
         /* unsupported flow */
         return false;
     }
 
     /* if unsupported hashtype was set */
     if (new_hashtypes != (new_hashtypes & vi->rss_hash_types_supported))
         return false;
 
     if (new_hashtypes != vi->rss_hash_types_saved) {
         vi->rss_hash_types_saved = new_hashtypes;
         vi->ctrl->rss.hash_types = vi->rss_hash_types_saved;
         if (vi->dev->features & NETIF_F_RXHASH)
             return virtnet_commit_rss_command(vi);
     }
 
     return true;
 }
 
 static void virtnet_get_drvinfo(struct net_device *dev,
                 struct ethtool_drvinfo *info)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     struct virtio_device *vdev = vi->vdev;
 
     strlcpy(info->driver, KBUILD_MODNAME, sizeof(info->driver));
     strlcpy(info->version, VIRTNET_DRIVER_VERSION, sizeof(info->version));
     strlcpy(info->bus_info, virtio_bus_name(vdev), sizeof(info->bus_info));
 
 }
 
 /* TODO: Eliminate OOO packets during switching */
 static int virtnet_set_channels(struct net_device *dev,
                 struct ethtool_channels *channels)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     u16 queue_pairs = channels->combined_count;
     int err;
 
     /* We don't support separate rx/tx channels.
      * We don't allow setting 'other' channels.
      */
     if (channels->rx_count || channels->tx_count || channels->other_count)
         return -EINVAL;
 
     if (queue_pairs > vi->max_queue_pairs || queue_pairs == 0)
         return -EINVAL;
 
     /* For now we don't support modifying channels while XDP is loaded
      * also when XDP is loaded all RX queues have XDP programs so we only
      * need to check a single RX queue.
      */
     if (vi->rq[0].xdp_prog)
         return -EINVAL;
 
     cpus_read_lock();
     err = _virtnet_set_queues(vi, queue_pairs);
     if (err) {
         cpus_read_unlock();
         goto err;
     }
     virtnet_set_affinity(vi);
     cpus_read_unlock();
 
     netif_set_real_num_tx_queues(dev, queue_pairs);
     netif_set_real_num_rx_queues(dev, queue_pairs);
  err:
     return err;
 }
 
 static void virtnet_get_strings(struct net_device *dev, u32 stringset, u8 *data)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     unsigned int i, j;
     u8 *p = data;
 
     switch (stringset) {
     case ETH_SS_STATS:
         for (i = 0; i < vi->curr_queue_pairs; i++) {
             for (j = 0; j < VIRTNET_RQ_STATS_LEN; j++)
                 ethtool_sprintf(&p, "rx_queue_%u_%s", i,
                         virtnet_rq_stats_desc[j].desc);
         }
 
         for (i = 0; i < vi->curr_queue_pairs; i++) {
             for (j = 0; j < VIRTNET_SQ_STATS_LEN; j++)
                 ethtool_sprintf(&p, "tx_queue_%u_%s", i,
                         virtnet_sq_stats_desc[j].desc);
         }
         break;
     }
 }
 
 static int virtnet_get_sset_count(struct net_device *dev, int sset)
 {
     struct virtnet_info *vi = netdev_priv(dev);
 
     switch (sset) {
     case ETH_SS_STATS:
         return vi->curr_queue_pairs * (VIRTNET_RQ_STATS_LEN +
                            VIRTNET_SQ_STATS_LEN);
     default:
         return -EOPNOTSUPP;
     }
 }
 
 static void virtnet_get_ethtool_stats(struct net_device *dev,
                       struct ethtool_stats *stats, u64 *data)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     unsigned int idx = 0, start, i, j;
     const u8 *stats_base;
     size_t offset;
 
     for (i = 0; i < vi->curr_queue_pairs; i++) {
         struct receive_queue *rq = &vi->rq[i];
 
         stats_base = (u8 *)&rq->stats;
         do {
             start = u64_stats_fetch_begin_irq(&rq->stats.syncp);
             for (j = 0; j < VIRTNET_RQ_STATS_LEN; j++) {
                 offset = virtnet_rq_stats_desc[j].offset;
                 data[idx + j] = *(u64 *)(stats_base + offset);
             }
         } while (u64_stats_fetch_retry_irq(&rq->stats.syncp, start));
         idx += VIRTNET_RQ_STATS_LEN;
     }
 
     for (i = 0; i < vi->curr_queue_pairs; i++) {
         struct send_queue *sq = &vi->sq[i];
 
         stats_base = (u8 *)&sq->stats;
         do {
             start = u64_stats_fetch_begin_irq(&sq->stats.syncp);
             for (j = 0; j < VIRTNET_SQ_STATS_LEN; j++) {
                 offset = virtnet_sq_stats_desc[j].offset;
                 data[idx + j] = *(u64 *)(stats_base + offset);
             }
         } while (u64_stats_fetch_retry_irq(&sq->stats.syncp, start));
         idx += VIRTNET_SQ_STATS_LEN;
     }
 }
 
 static void virtnet_get_channels(struct net_device *dev,
                  struct ethtool_channels *channels)
 {
     struct virtnet_info *vi = netdev_priv(dev);
 
     channels->combined_count = vi->curr_queue_pairs;
     channels->max_combined = vi->max_queue_pairs;
     channels->max_other = 0;
     channels->rx_count = 0;
     channels->tx_count = 0;
     channels->other_count = 0;
 }
 
 static int virtnet_set_link_ksettings(struct net_device *dev,
                       const struct ethtool_link_ksettings *cmd)
 {
     struct virtnet_info *vi = netdev_priv(dev);
 
     return ethtool_virtdev_set_link_ksettings(dev, cmd,
                           &vi->speed, &vi->duplex);
 }
 
 static int virtnet_get_link_ksettings(struct net_device *dev,
                       struct ethtool_link_ksettings *cmd)
 {
     struct virtnet_info *vi = netdev_priv(dev);
 
     cmd->base.speed = vi->speed;
     cmd->base.duplex = vi->duplex;
     cmd->base.port = PORT_OTHER;
 
     return 0;
 }
 
 static int virtnet_send_notf_coal_cmds(struct virtnet_info *vi,
                        struct ethtool_coalesce *ec)
 {
     struct scatterlist sgs_tx, sgs_rx;
     struct virtio_net_ctrl_coal_tx coal_tx;
     struct virtio_net_ctrl_coal_rx coal_rx;
 
     coal_tx.tx_usecs = cpu_to_le32(ec->tx_coalesce_usecs);
     coal_tx.tx_max_packets = cpu_to_le32(ec->tx_max_coalesced_frames);
     sg_init_one(&sgs_tx, &coal_tx, sizeof(coal_tx));
 
     if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
                   VIRTIO_NET_CTRL_NOTF_COAL_TX_SET,
                   &sgs_tx))
         return -EINVAL;
 
     /* Save parameters */
     vi->tx_usecs = ec->tx_coalesce_usecs;
     vi->tx_max_packets = ec->tx_max_coalesced_frames;
 
     coal_rx.rx_usecs = cpu_to_le32(ec->rx_coalesce_usecs);
     coal_rx.rx_max_packets = cpu_to_le32(ec->rx_max_coalesced_frames);
     sg_init_one(&sgs_rx, &coal_rx, sizeof(coal_rx));
 
     if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
                   VIRTIO_NET_CTRL_NOTF_COAL_RX_SET,
                   &sgs_rx))
         return -EINVAL;
 
     /* Save parameters */
     vi->rx_usecs = ec->rx_coalesce_usecs;
     vi->rx_max_packets = ec->rx_max_coalesced_frames;
 
     return 0;
 }
 
 static int virtnet_coal_params_supported(struct ethtool_coalesce *ec)
 {
     /* usecs coalescing is supported only if VIRTIO_NET_F_NOTF_COAL
      * feature is negotiated.
      */
     if (ec->rx_coalesce_usecs || ec->tx_coalesce_usecs)
         return -EOPNOTSUPP;
 
     if (ec->tx_max_coalesced_frames > 1 ||
         ec->rx_max_coalesced_frames != 1)
         return -EINVAL;
 
     return 0;
 }
 
 static int virtnet_set_coalesce(struct net_device *dev,
                 struct ethtool_coalesce *ec,
                 struct kernel_ethtool_coalesce *kernel_coal,
                 struct netlink_ext_ack *extack)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     int ret, i, napi_weight;
     bool update_napi = false;
 
     /* Can't change NAPI weight if the link is up */
     napi_weight = ec->tx_max_coalesced_frames ? NAPI_POLL_WEIGHT : 0;
     if (napi_weight ^ vi->sq[0].napi.weight) {
         if (dev->flags & IFF_UP)
             return -EBUSY;
         else
             update_napi = true;
     }
 
     if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL))
         ret = virtnet_send_notf_coal_cmds(vi, ec);
     else
         ret = virtnet_coal_params_supported(ec);
 
     if (ret)
         return ret;
 
     if (update_napi) {
         for (i = 0; i < vi->max_queue_pairs; i++)
             vi->sq[i].napi.weight = napi_weight;
     }
 
     return ret;
 }
 
 static int virtnet_get_coalesce(struct net_device *dev,
                 struct ethtool_coalesce *ec,
                 struct kernel_ethtool_coalesce *kernel_coal,
                 struct netlink_ext_ack *extack)
 {
     struct virtnet_info *vi = netdev_priv(dev);
 
     if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
         ec->rx_coalesce_usecs = vi->rx_usecs;
         ec->tx_coalesce_usecs = vi->tx_usecs;
         ec->tx_max_coalesced_frames = vi->tx_max_packets;
         ec->rx_max_coalesced_frames = vi->rx_max_packets;
     } else {
         ec->rx_max_coalesced_frames = 1;
 
         if (vi->sq[0].napi.weight)
             ec->tx_max_coalesced_frames = 1;
     }
 
     return 0;
 }
 
 static void virtnet_init_settings(struct net_device *dev)
 {
     struct virtnet_info *vi = netdev_priv(dev);
 
     vi->speed = SPEED_UNKNOWN;
     vi->duplex = DUPLEX_UNKNOWN;
 }
 
 static void virtnet_update_settings(struct virtnet_info *vi)
 {
     u32 speed;
     u8 duplex;
 
     if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_SPEED_DUPLEX))
         return;
 
     virtio_cread_le(vi->vdev, struct virtio_net_config, speed, &speed);
 
     if (ethtool_validate_speed(speed))
         vi->speed = speed;
 
     virtio_cread_le(vi->vdev, struct virtio_net_config, duplex, &duplex);
 
     if (ethtool_validate_duplex(duplex))
         vi->duplex = duplex;
 }
 
 static u32 virtnet_get_rxfh_key_size(struct net_device *dev)
 {
     return ((struct virtnet_info *)netdev_priv(dev))->rss_key_size;
 }
 
 static u32 virtnet_get_rxfh_indir_size(struct net_device *dev)
 {
     return ((struct virtnet_info *)netdev_priv(dev))->rss_indir_table_size;
 }
 
 static int virtnet_get_rxfh(struct net_device *dev, u32 *indir, u8 *key, u8 *hfunc)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     int i;
 
     if (indir) {
         for (i = 0; i < vi->rss_indir_table_size; ++i)
             indir[i] = vi->ctrl->rss.indirection_table[i];
     }
 
     if (key)
         memcpy(key, vi->ctrl->rss.key, vi->rss_key_size);
 
     if (hfunc)
         *hfunc = ETH_RSS_HASH_TOP;
 
     return 0;
 }
 
 static int virtnet_set_rxfh(struct net_device *dev, const u32 *indir, const u8 *key, const u8 hfunc)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     int i;
 
     if (hfunc != ETH_RSS_HASH_NO_CHANGE && hfunc != ETH_RSS_HASH_TOP)
         return -EOPNOTSUPP;
 
     if (indir) {
         for (i = 0; i < vi->rss_indir_table_size; ++i)
             vi->ctrl->rss.indirection_table[i] = indir[i];
     }
     if (key)
         memcpy(vi->ctrl->rss.key, key, vi->rss_key_size);
 
     virtnet_commit_rss_command(vi);
 
     return 0;
 }
 
 static int virtnet_get_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info, u32 *rule_locs)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     int rc = 0;
 
     switch (info->cmd) {
     case ETHTOOL_GRXRINGS:
         info->data = vi->curr_queue_pairs;
         break;
     case ETHTOOL_GRXFH:
         virtnet_get_hashflow(vi, info);
         break;
     default:
         rc = -EOPNOTSUPP;
     }
 
     return rc;
 }
 
 static int virtnet_set_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     int rc = 0;
 
     switch (info->cmd) {
     case ETHTOOL_SRXFH:
         if (!virtnet_set_hashflow(vi, info))
             rc = -EINVAL;
 
         break;
     default:
         rc = -EOPNOTSUPP;
     }
 
     return rc;
 }
 
 static const struct ethtool_ops virtnet_ethtool_ops = {
     .supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES |
         ETHTOOL_COALESCE_USECS,
     .get_drvinfo = virtnet_get_drvinfo,
     .get_link = ethtool_op_get_link,
     .get_ringparam = virtnet_get_ringparam,
     .set_ringparam = virtnet_set_ringparam,
     .get_strings = virtnet_get_strings,
     .get_sset_count = virtnet_get_sset_count,
     .get_ethtool_stats = virtnet_get_ethtool_stats,
     .set_channels = virtnet_set_channels,
     .get_channels = virtnet_get_channels,
     .get_ts_info = ethtool_op_get_ts_info,
     .get_link_ksettings = virtnet_get_link_ksettings,
     .set_link_ksettings = virtnet_set_link_ksettings,
     .set_coalesce = virtnet_set_coalesce,
     .get_coalesce = virtnet_get_coalesce,
     .get_rxfh_key_size = virtnet_get_rxfh_key_size,
     .get_rxfh_indir_size = virtnet_get_rxfh_indir_size,
     .get_rxfh = virtnet_get_rxfh,
     .set_rxfh = virtnet_set_rxfh,
     .get_rxnfc = virtnet_get_rxnfc,
     .set_rxnfc = virtnet_set_rxnfc,
 };
 
 static void virtnet_freeze_down(struct virtio_device *vdev)
 {
     struct virtnet_info *vi = vdev->priv;
 
     /* Make sure no work handler is accessing the device */
     flush_work(&vi->config_work);
 
     netif_tx_lock_bh(vi->dev);
     netif_device_detach(vi->dev);
     netif_tx_unlock_bh(vi->dev);
     if (netif_running(vi->dev))
         virtnet_close(vi->dev);
 }
 
 static int init_vqs(struct virtnet_info *vi);
 
 static int virtnet_restore_up(struct virtio_device *vdev)
 {
     struct virtnet_info *vi = vdev->priv;
     int err;
 
     err = init_vqs(vi);
     if (err)
         return err;
 
     virtio_device_ready(vdev);
 
     enable_delayed_refill(vi);
 
     if (netif_running(vi->dev)) {
         err = virtnet_open(vi->dev);
         if (err)
             return err;
     }
 
     netif_tx_lock_bh(vi->dev);
     netif_device_attach(vi->dev);
     netif_tx_unlock_bh(vi->dev);
     return err;
 }
 
 static int virtnet_set_guest_offloads(struct virtnet_info *vi, u64 offloads)
 {
     struct scatterlist sg;
     vi->ctrl->offloads = cpu_to_virtio64(vi->vdev, offloads);
 
     sg_init_one(&sg, &vi->ctrl->offloads, sizeof(vi->ctrl->offloads));
 
     if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_GUEST_OFFLOADS,
                   VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET, &sg)) {
         dev_warn(&vi->dev->dev, "Fail to set guest offload.\n");
         return -EINVAL;
     }
 
     return 0;
 }
 
 static int virtnet_clear_guest_offloads(struct virtnet_info *vi)
 {
     u64 offloads = 0;
 
     if (!vi->guest_offloads)
         return 0;
 
     return virtnet_set_guest_offloads(vi, offloads);
 }
 
 static int virtnet_restore_guest_offloads(struct virtnet_info *vi)
 {
     u64 offloads = vi->guest_offloads;
 
     if (!vi->guest_offloads)
         return 0;
 
     return virtnet_set_guest_offloads(vi, offloads);
 }
 
 static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
                struct netlink_ext_ack *extack)
 {
     unsigned long int max_sz = PAGE_SIZE - sizeof(struct padded_vnet_hdr);
     struct virtnet_info *vi = netdev_priv(dev);
     struct bpf_prog *old_prog;
     u16 xdp_qp = 0, curr_qp;
     int i, err;
 
     if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS)
         && (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
             virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6) ||
             virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_ECN) ||
         virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_UFO) ||
         virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_CSUM))) {
         NL_SET_ERR_MSG_MOD(extack, "Can't set XDP while host is implementing GRO_HW/CSUM, disable GRO_HW/CSUM first");
         return -EOPNOTSUPP;
     }
 
     if (vi->mergeable_rx_bufs && !vi->any_header_sg) {
         NL_SET_ERR_MSG_MOD(extack, "XDP expects header/data in single page, any_header_sg required");
         return -EINVAL;
     }
 
     if (dev->mtu > max_sz) {
         NL_SET_ERR_MSG_MOD(extack, "MTU too large to enable XDP");
         netdev_warn(dev, "XDP requires MTU less than %lu\n", max_sz);
         return -EINVAL;
     }
 
     curr_qp = vi->curr_queue_pairs - vi->xdp_queue_pairs;
     if (prog)
         xdp_qp = nr_cpu_ids;
 
     /* XDP requires extra queues for XDP_TX */
     if (curr_qp + xdp_qp > vi->max_queue_pairs) {
         netdev_warn_once(dev, "XDP request %i queues but max is %i. XDP_TX and XDP_REDIRECT will operate in a slower locked tx mode.\n",
                  curr_qp + xdp_qp, vi->max_queue_pairs);
         xdp_qp = 0;
     }
 
     old_prog = rtnl_dereference(vi->rq[0].xdp_prog);
     if (!prog && !old_prog)
         return 0;
 
     if (prog)
         bpf_prog_add(prog, vi->max_queue_pairs - 1);
 
     /* Make sure NAPI is not using any XDP TX queues for RX. */
     if (netif_running(dev)) {
         for (i = 0; i < vi->max_queue_pairs; i++) {
             napi_disable(&vi->rq[i].napi);
             virtnet_napi_tx_disable(&vi->sq[i].napi);
         }
     }
 
     if (!prog) {
         for (i = 0; i < vi->max_queue_pairs; i++) {
             rcu_assign_pointer(vi->rq[i].xdp_prog, prog);
             if (i == 0)
                 virtnet_restore_guest_offloads(vi);
         }
         synchronize_net();
     }
 
     err = _virtnet_set_queues(vi, curr_qp + xdp_qp);
     if (err)
         goto err;
     netif_set_real_num_rx_queues(dev, curr_qp + xdp_qp);
     vi->xdp_queue_pairs = xdp_qp;
 
     if (prog) {
         vi->xdp_enabled = true;
         for (i = 0; i < vi->max_queue_pairs; i++) {
             rcu_assign_pointer(vi->rq[i].xdp_prog, prog);
             if (i == 0 && !old_prog)
                 virtnet_clear_guest_offloads(vi);
         }
     } else {
         vi->xdp_enabled = false;
     }
 
     for (i = 0; i < vi->max_queue_pairs; i++) {
         if (old_prog)
             bpf_prog_put(old_prog);
         if (netif_running(dev)) {
             virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);
             virtnet_napi_tx_enable(vi, vi->sq[i].vq,
                            &vi->sq[i].napi);
         }
     }
 
     return 0;
 
 err:
     if (!prog) {
         virtnet_clear_guest_offloads(vi);
         for (i = 0; i < vi->max_queue_pairs; i++)
             rcu_assign_pointer(vi->rq[i].xdp_prog, old_prog);
     }
 
     if (netif_running(dev)) {
         for (i = 0; i < vi->max_queue_pairs; i++) {
             virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);
             virtnet_napi_tx_enable(vi, vi->sq[i].vq,
                            &vi->sq[i].napi);
         }
     }
     if (prog)
         bpf_prog_sub(prog, vi->max_queue_pairs - 1);
     return err;
 }
 
 static int virtnet_xdp(struct net_device *dev, struct netdev_bpf *xdp)
 {
     switch (xdp->command) {
     case XDP_SETUP_PROG:
         return virtnet_xdp_set(dev, xdp->prog, xdp->extack);
     default:
         return -EINVAL;
     }
 }
 
 static int virtnet_get_phys_port_name(struct net_device *dev, char *buf,
                       size_t len)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     int ret;
 
     if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_STANDBY))
         return -EOPNOTSUPP;
 
     ret = snprintf(buf, len, "sby");
     if (ret >= len)
         return -EOPNOTSUPP;
 
     return 0;
 }
 
 static int virtnet_set_features(struct net_device *dev,
                 netdev_features_t features)
 {
     struct virtnet_info *vi = netdev_priv(dev);
     u64 offloads;
     int err;
 
     if ((dev->features ^ features) & NETIF_F_GRO_HW) {
         if (vi->xdp_enabled)
             return -EBUSY;
 
         if (features & NETIF_F_GRO_HW)
             offloads = vi->guest_offloads_capable;
         else
             offloads = vi->guest_offloads_capable &
                    ~GUEST_OFFLOAD_GRO_HW_MASK;
 
         err = virtnet_set_guest_offloads(vi, offloads);
         if (err)
             return err;
         vi->guest_offloads = offloads;
     }
 
     if ((dev->features ^ features) & NETIF_F_RXHASH) {
         if (features & NETIF_F_RXHASH)
             vi->ctrl->rss.hash_types = vi->rss_hash_types_saved;
         else
             vi->ctrl->rss.hash_types = VIRTIO_NET_HASH_REPORT_NONE;
 
         if (!virtnet_commit_rss_command(vi))
             return -EINVAL;
     }
 
     return 0;
 }
 
 static void virtnet_tx_timeout(struct net_device *dev, unsigned int txqueue)
 {
     struct virtnet_info *priv = netdev_priv(dev);
     struct send_queue *sq = &priv->sq[txqueue];
     struct netdev_queue *txq = netdev_get_tx_queue(dev, txqueue);
 
     u64_stats_update_begin(&sq->stats.syncp);
     sq->stats.tx_timeouts++;
     u64_stats_update_end(&sq->stats.syncp);
 
     netdev_err(dev, "TX timeout on queue: %u, sq: %s, vq: 0x%x, name: %s, %u usecs ago\n",
            txqueue, sq->name, sq->vq->index, sq->vq->name,
            jiffies_to_usecs(jiffies - READ_ONCE(txq->trans_start)));
 }
 
 static const struct net_device_ops virtnet_netdev = {
     .ndo_open            = virtnet_open,
     .ndo_stop            = virtnet_close,
     .ndo_start_xmit      = start_xmit,
     .ndo_validate_addr   = eth_validate_addr,
     .ndo_set_mac_address = virtnet_set_mac_address,
     .ndo_set_rx_mode     = virtnet_set_rx_mode,
     .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_bpf        = virtnet_xdp,
     .ndo_xdp_xmit       = virtnet_xdp_xmit,
     .ndo_features_check = passthru_features_check,
     .ndo_get_phys_port_name = virtnet_get_phys_port_name,
     .ndo_set_features   = virtnet_set_features,
     .ndo_tx_timeout     = virtnet_tx_timeout,
 };
 
 static void virtnet_config_changed_work(struct work_struct *work)
 {
     struct virtnet_info *vi =
         container_of(work, struct virtnet_info, config_work);
     u16 v;
 
     if (virtio_cread_feature(vi->vdev, VIRTIO_NET_F_STATUS,
                  struct virtio_net_config, status, &v) < 0)
         return;
 
     if (v & VIRTIO_NET_S_ANNOUNCE) {
         netdev_notify_peers(vi->dev);
         virtnet_ack_link_announce(vi);
     }
 
     /* Ignore unknown (future) status bits */
     v &= VIRTIO_NET_S_LINK_UP;
 
     if (vi->status == v)
         return;
 
     vi->status = v;
 
     if (vi->status & VIRTIO_NET_S_LINK_UP) {
         virtnet_update_settings(vi);
         netif_carrier_on(vi->dev);
         netif_tx_wake_all_queues(vi->dev);
     } else {
         netif_carrier_off(vi->dev);
         netif_tx_stop_all_queues(vi->dev);
     }
 }
 
 static void virtnet_config_changed(struct virtio_device *vdev)
 {
     struct virtnet_info *vi = vdev->priv;
 
     schedule_work(&vi->config_work);
 }
 
 static void virtnet_free_queues(struct virtnet_info *vi)
 {
     int i;
 
     for (i = 0; i < vi->max_queue_pairs; i++) {
         __netif_napi_del(&vi->rq[i].napi);
         __netif_napi_del(&vi->sq[i].napi);
     }
 
     /* We called __netif_napi_del(),
      * we need to respect an RCU grace period before freeing vi->rq
      */
     synchronize_net();
 
     kfree(vi->rq);
     kfree(vi->sq);
     kfree(vi->ctrl);
 }
 
 static void _free_receive_bufs(struct virtnet_info *vi)
 {
     struct bpf_prog *old_prog;
     int i;
 
     for (i = 0; i < vi->max_queue_pairs; i++) {
         while (vi->rq[i].pages)
             __free_pages(get_a_page(&vi->rq[i], GFP_KERNEL), 0);
 
         old_prog = rtnl_dereference(vi->rq[i].xdp_prog);
         RCU_INIT_POINTER(vi->rq[i].xdp_prog, NULL);
         if (old_prog)
             bpf_prog_put(old_prog);
     }
 }
 
 static void free_receive_bufs(struct virtnet_info *vi)
 {
     rtnl_lock();
     _free_receive_bufs(vi);
     rtnl_unlock();
 }
 
 static void free_receive_page_frags(struct virtnet_info *vi)
 {
     int i;
     for (i = 0; i < vi->max_queue_pairs; i++)
         if (vi->rq[i].alloc_frag.page)
             put_page(vi->rq[i].alloc_frag.page);
 }
 
 static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf)
 {
     if (!is_xdp_frame(buf))
         dev_kfree_skb(buf);
     else
         xdp_return_frame(ptr_to_xdp(buf));
 }
 
 static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf)
 {
     struct virtnet_info *vi = vq->vdev->priv;
     int i = vq2rxq(vq);
 
     if (vi->mergeable_rx_bufs)
         put_page(virt_to_head_page(buf));
     else if (vi->big_packets)
         give_pages(&vi->rq[i], buf);
     else
         put_page(virt_to_head_page(buf));
 }
 
 static void free_unused_bufs(struct virtnet_info *vi)
 {
     void *buf;
     int i;
 
     for (i = 0; i < vi->max_queue_pairs; i++) {
         struct virtqueue *vq = vi->sq[i].vq;
         while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
             virtnet_sq_free_unused_buf(vq, buf);
     }
 
     for (i = 0; i < vi->max_queue_pairs; i++) {
         struct virtqueue *vq = vi->rq[i].vq;
         while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
             virtnet_rq_free_unused_buf(vq, buf);
     }
 }
 
 static void virtnet_del_vqs(struct virtnet_info *vi)
 {
     struct virtio_device *vdev = vi->vdev;
 
     virtnet_clean_affinity(vi);
 
     vdev->config->del_vqs(vdev);
 
     virtnet_free_queues(vi);
 }
 
 /* How large should a single buffer be so a queue full of these can fit at
  * least one full packet?
  * Logic below assumes the mergeable buffer header is used.
  */
 static unsigned int mergeable_min_buf_len(struct virtnet_info *vi, struct virtqueue *vq)
 {
     const unsigned int hdr_len = vi->hdr_len;
     unsigned int rq_size = virtqueue_get_vring_size(vq);
     unsigned int packet_len = vi->big_packets ? IP_MAX_MTU : vi->dev->max_mtu;
     unsigned int buf_len = hdr_len + ETH_HLEN + VLAN_HLEN + packet_len;
     unsigned int min_buf_len = DIV_ROUND_UP(buf_len, rq_size);
 
     return max(max(min_buf_len, hdr_len) - hdr_len,
            (unsigned int)GOOD_PACKET_LEN);
 }
 
 static int virtnet_find_vqs(struct virtnet_info *vi)
 {
     vq_callback_t **callbacks;
     struct virtqueue **vqs;
     int ret = -ENOMEM;
     int i, total_vqs;
     const char **names;
     bool *ctx;
 
     /* We expect 1 RX virtqueue followed by 1 TX virtqueue, followed by
      * possible N-1 RX/TX queue pairs used in multiqueue mode, followed by
      * possible control vq.
      */
     total_vqs = vi->max_queue_pairs * 2 +
             virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ);
 
     /* Allocate space for find_vqs parameters */
     vqs = kcalloc(total_vqs, sizeof(*vqs), GFP_KERNEL);
     if (!vqs)
         goto err_vq;
     callbacks = kmalloc_array(total_vqs, sizeof(*callbacks), GFP_KERNEL);
     if (!callbacks)
         goto err_callback;
     names = kmalloc_array(total_vqs, sizeof(*names), GFP_KERNEL);
     if (!names)
         goto err_names;
     if (!vi->big_packets || vi->mergeable_rx_bufs) {
         ctx = kcalloc(total_vqs, sizeof(*ctx), GFP_KERNEL);
         if (!ctx)
             goto err_ctx;
     } else {
         ctx = NULL;
     }
 
     /* Parameters for control virtqueue, if any */
     if (vi->has_cvq) {
         callbacks[total_vqs - 1] = NULL;
         names[total_vqs - 1] = "control";
     }
 
     /* Allocate/initialize parameters for send/receive virtqueues */
     for (i = 0; i < vi->max_queue_pairs; i++) {
         callbacks[rxq2vq(i)] = skb_recv_done;
         callbacks[txq2vq(i)] = skb_xmit_done;
         sprintf(vi->rq[i].name, "input.%d", i);
         sprintf(vi->sq[i].name, "output.%d", i);
         names[rxq2vq(i)] = vi->rq[i].name;
         names[txq2vq(i)] = vi->sq[i].name;
         if (ctx)
             ctx[rxq2vq(i)] = true;
     }
 
     ret = virtio_find_vqs_ctx(vi->vdev, total_vqs, vqs, callbacks,
                   names, ctx, NULL);
     if (ret)
         goto err_find;
 
     if (vi->has_cvq) {
         vi->cvq = vqs[total_vqs - 1];
         if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VLAN))
             vi->dev->features |= NETIF_F_HW_VLAN_CTAG_FILTER;
     }
 
     for (i = 0; i < vi->max_queue_pairs; i++) {
         vi->rq[i].vq = vqs[rxq2vq(i)];
         vi->rq[i].min_buf_len = mergeable_min_buf_len(vi, vi->rq[i].vq);
         vi->sq[i].vq = vqs[txq2vq(i)];
     }
 
     /* run here: ret == 0. */
 
 
 err_find:
     kfree(ctx);
 err_ctx:
     kfree(names);
 err_names:
     kfree(callbacks);
 err_callback:
     kfree(vqs);
 err_vq:
     return ret;
 }
 
 static int virtnet_alloc_queues(struct virtnet_info *vi)
 {
     int i;
 
     if (vi->has_cvq) {
         vi->ctrl = kzalloc(sizeof(*vi->ctrl), GFP_KERNEL);
         if (!vi->ctrl)
             goto err_ctrl;
     } else {
         vi->ctrl = NULL;
     }
     vi->sq = kcalloc(vi->max_queue_pairs, sizeof(*vi->sq), GFP_KERNEL);
     if (!vi->sq)
         goto err_sq;
     vi->rq = kcalloc(vi->max_queue_pairs, sizeof(*vi->rq), GFP_KERNEL);
     if (!vi->rq)
         goto err_rq;
 
     INIT_DELAYED_WORK(&vi->refill, refill_work);
     for (i = 0; i < vi->max_queue_pairs; i++) {
         vi->rq[i].pages = NULL;
         netif_napi_add_weight(vi->dev, &vi->rq[i].napi, virtnet_poll,
                       napi_weight);
         netif_napi_add_tx_weight(vi->dev, &vi->sq[i].napi,
                      virtnet_poll_tx,
                      napi_tx ? napi_weight : 0);
 
         sg_init_table(vi->rq[i].sg, ARRAY_SIZE(vi->rq[i].sg));
         ewma_pkt_len_init(&vi->rq[i].mrg_avg_pkt_len);
         sg_init_table(vi->sq[i].sg, ARRAY_SIZE(vi->sq[i].sg));
 
         u64_stats_init(&vi->rq[i].stats.syncp);
         u64_stats_init(&vi->sq[i].stats.syncp);
     }
 
     return 0;
 
 err_rq:
     kfree(vi->sq);
 err_sq:
     kfree(vi->ctrl);
 err_ctrl:
     return -ENOMEM;
 }
 
 static int init_vqs(struct virtnet_info *vi)
 {
     int ret;
 
     /* Allocate send & receive queues */
     ret = virtnet_alloc_queues(vi);
     if (ret)
         goto err;
 
     ret = virtnet_find_vqs(vi);
     if (ret)
         goto err_free;
 
     cpus_read_lock();
     virtnet_set_affinity(vi);
     cpus_read_unlock();
 
     return 0;
 
 err_free:
     virtnet_free_queues(vi);
 err:
     return ret;
 }
 
 #ifdef CONFIG_SYSFS
 static ssize_t mergeable_rx_buffer_size_show(struct netdev_rx_queue *queue,
         char *buf)
 {
     struct virtnet_info *vi = netdev_priv(queue->dev);
     unsigned int queue_index = get_netdev_rx_queue_index(queue);
     unsigned int headroom = virtnet_get_headroom(vi);
     unsigned int tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
     struct ewma_pkt_len *avg;
 
     BUG_ON(queue_index >= vi->max_queue_pairs);
     avg = &vi->rq[queue_index].mrg_avg_pkt_len;
     return sprintf(buf, "%u\n",
                get_mergeable_buf_len(&vi->rq[queue_index], avg,
                        SKB_DATA_ALIGN(headroom + tailroom)));
 }
 
 static struct rx_queue_attribute mergeable_rx_buffer_size_attribute =
     __ATTR_RO(mergeable_rx_buffer_size);
 
 static struct attribute *virtio_net_mrg_rx_attrs[] = {
     &mergeable_rx_buffer_size_attribute.attr,
     NULL
 };
 
 static const struct attribute_group virtio_net_mrg_rx_group = {
     .name = "virtio_net",
     .attrs = virtio_net_mrg_rx_attrs
 };
 #endif
 
 static bool virtnet_fail_on_feature(struct virtio_device *vdev,
                     unsigned int fbit,
                     const char *fname, const char *dname)
 {
     if (!virtio_has_feature(vdev, fbit))
         return false;
 
     dev_err(&vdev->dev, "device advertises feature %s but not %s",
         fname, dname);
 
     return true;
 }
 
 #define VIRTNET_FAIL_ON(vdev, fbit, dbit)           \
     virtnet_fail_on_feature(vdev, fbit, #fbit, dbit)
 
 static bool virtnet_validate_features(struct virtio_device *vdev)
 {
     if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ) &&
         (VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_RX,
                  "VIRTIO_NET_F_CTRL_VQ") ||
          VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_VLAN,
                  "VIRTIO_NET_F_CTRL_VQ") ||
          VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_GUEST_ANNOUNCE,
                  "VIRTIO_NET_F_CTRL_VQ") ||
          VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_MQ, "VIRTIO_NET_F_CTRL_VQ") ||
          VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR,
                  "VIRTIO_NET_F_CTRL_VQ") ||
          VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_RSS,
                  "VIRTIO_NET_F_CTRL_VQ") ||
          VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_HASH_REPORT,
                  "VIRTIO_NET_F_CTRL_VQ") ||
          VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_NOTF_COAL,
                  "VIRTIO_NET_F_CTRL_VQ"))) {
         return false;
     }
 
     return true;
 }
 
 #define MIN_MTU ETH_MIN_MTU
 #define MAX_MTU ETH_MAX_MTU
 
 static int virtnet_validate(struct virtio_device *vdev)
 {
     if (!vdev->config->get) {
         dev_err(&vdev->dev, "%s failure: config access disabled\n",
             __func__);
         return -EINVAL;
     }
 
     if (!virtnet_validate_features(vdev))
         return -EINVAL;
 
     if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
         int mtu = virtio_cread16(vdev,
                      offsetof(struct virtio_net_config,
                           mtu));
         if (mtu < MIN_MTU)
             __virtio_clear_bit(vdev, VIRTIO_NET_F_MTU);
     }
 
     return 0;
 }
 
 static int virtnet_probe(struct virtio_device *vdev)
 {
     int i, err = -ENOMEM;
     struct net_device *dev;
     struct virtnet_info *vi;
     u16 max_queue_pairs;
     int mtu;
 
     /* Find if host supports multiqueue/rss virtio_net device */
     max_queue_pairs = 1;
     if (virtio_has_feature(vdev, VIRTIO_NET_F_MQ) || virtio_has_feature(vdev, VIRTIO_NET_F_RSS))
         max_queue_pairs =
              virtio_cread16(vdev, offsetof(struct virtio_net_config, max_virtqueue_pairs));
 
     /* We need at least 2 queue's */
     if (max_queue_pairs < VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN ||
         max_queue_pairs > VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX ||
         !virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
         max_queue_pairs = 1;
 
     /* Allocate ourselves a network device with room for our info */
     dev = alloc_etherdev_mq(sizeof(struct virtnet_info), max_queue_pairs);
     if (!dev)
         return -ENOMEM;
 
     /* Set up network device as normal. */
     dev->priv_flags |= IFF_UNICAST_FLT | IFF_LIVE_ADDR_CHANGE |
                IFF_TX_SKB_NO_LINEAR;
     dev->netdev_ops = &virtnet_netdev;
     dev->features = NETIF_F_HIGHDMA;
 
     dev->ethtool_ops = &virtnet_ethtool_ops;
     SET_NETDEV_DEV(dev, &vdev->dev);
 
     /* Do we support "hardware" checksums? */
     if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
         /* This opens up the world of extra features. */
         dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG;
         if (csum)
             dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;
 
         if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
             dev->hw_features |= NETIF_F_TSO
                 | NETIF_F_TSO_ECN | NETIF_F_TSO6;
         }
         /* Individual feature bits: what can host handle? */
         if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO4))
             dev->hw_features |= NETIF_F_TSO;
         if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO6))
             dev->hw_features |= NETIF_F_TSO6;
         if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_ECN))
             dev->hw_features |= NETIF_F_TSO_ECN;
 
         dev->features |= NETIF_F_GSO_ROBUST;
 
         if (gso)
             dev->features |= dev->hw_features & NETIF_F_ALL_TSO;
         /* (!csum && gso) case will be fixed by register_netdev() */
     }
     if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_CSUM))
         dev->features |= NETIF_F_RXCSUM;
     if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
         virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6))
         dev->features |= NETIF_F_GRO_HW;
     if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
         dev->hw_features |= NETIF_F_GRO_HW;
 
     dev->vlan_features = dev->features;
 
     /* MTU range: 68 - 65535 */
     dev->min_mtu = MIN_MTU;
     dev->max_mtu = MAX_MTU;
 
     /* Configuration may specify what MAC to use.  Otherwise random. */
     if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) {
         u8 addr[ETH_ALEN];
 
         virtio_cread_bytes(vdev,
                    offsetof(struct virtio_net_config, mac),
                    addr, ETH_ALEN);
         eth_hw_addr_set(dev, addr);
     } else {
         eth_hw_addr_random(dev);
     }
 
     /* Set up our device-specific information */
     vi = netdev_priv(dev);
     vi->dev = dev;
     vi->vdev = vdev;
     vdev->priv = vi;
 
     INIT_WORK(&vi->config_work, virtnet_config_changed_work);
     spin_lock_init(&vi->refill_lock);
 
     /* If we can receive ANY GSO packets, we must allocate large ones. */
     if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
         virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6) ||
         virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_ECN) ||
         virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_UFO))
         vi->big_packets = true;
 
     if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
         vi->mergeable_rx_bufs = true;
 
     if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
         vi->rx_usecs = 0;
         vi->tx_usecs = 0;
         vi->tx_max_packets = 0;
         vi->rx_max_packets = 0;
     }
 
     if (virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT))
         vi->has_rss_hash_report = true;
 
     if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS))
         vi->has_rss = true;
 
     if (vi->has_rss || vi->has_rss_hash_report) {
         vi->rss_indir_table_size =
             virtio_cread16(vdev, offsetof(struct virtio_net_config,
                 rss_max_indirection_table_length));
         vi->rss_key_size =
             virtio_cread8(vdev, offsetof(struct virtio_net_config, rss_max_key_size));
 
         vi->rss_hash_types_supported =
             virtio_cread32(vdev, offsetof(struct virtio_net_config, supported_hash_types));
         vi->rss_hash_types_supported &=
                 ~(VIRTIO_NET_RSS_HASH_TYPE_IP_EX |
                   VIRTIO_NET_RSS_HASH_TYPE_TCP_EX |
                   VIRTIO_NET_RSS_HASH_TYPE_UDP_EX);
 
         dev->hw_features |= NETIF_F_RXHASH;
     }
 
     if (vi->has_rss_hash_report)
         vi->hdr_len = sizeof(struct virtio_net_hdr_v1_hash);
     else if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF) ||
          virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
         vi->hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
     else
         vi->hdr_len = sizeof(struct virtio_net_hdr);
 
     if (virtio_has_feature(vdev, VIRTIO_F_ANY_LAYOUT) ||
         virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
         vi->any_header_sg = true;
 
     if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
         vi->has_cvq = true;
 
     if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
         mtu = virtio_cread16(vdev,
                      offsetof(struct virtio_net_config,
                           mtu));
         if (mtu < dev->min_mtu) {
             /* Should never trigger: MTU was previously validated
              * in virtnet_validate.
              */
             dev_err(&vdev->dev,
                 "device MTU appears to have changed it is now %d < %d",
                 mtu, dev->min_mtu);
             err = -EINVAL;
             goto free;
         }
 
         dev->mtu = mtu;
         dev->max_mtu = mtu;
 
         /* TODO: size buffers correctly in this case. */
         if (dev->mtu > ETH_DATA_LEN)
             vi->big_packets = true;
     }
 
     if (vi->any_header_sg)
         dev->needed_headroom = vi->hdr_len;
 
     /* Enable multiqueue by default */
     if (num_online_cpus() >= max_queue_pairs)
         vi->curr_queue_pairs = max_queue_pairs;
     else
         vi->curr_queue_pairs = num_online_cpus();
     vi->max_queue_pairs = max_queue_pairs;
 
     /* Allocate/initialize the rx/tx queues, and invoke find_vqs */
     err = init_vqs(vi);
     if (err)
         goto free;
 
 #ifdef CONFIG_SYSFS
     if (vi->mergeable_rx_bufs)
         dev->sysfs_rx_queue_group = &virtio_net_mrg_rx_group;
 #endif
     netif_set_real_num_tx_queues(dev, vi->curr_queue_pairs);
     netif_set_real_num_rx_queues(dev, vi->curr_queue_pairs);
 
     virtnet_init_settings(dev);
 
     if (virtio_has_feature(vdev, VIRTIO_NET_F_STANDBY)) {
         vi->failover = net_failover_create(vi->dev);
         if (IS_ERR(vi->failover)) {
             err = PTR_ERR(vi->failover);
             goto free_vqs;
         }
     }
 
     if (vi->has_rss || vi->has_rss_hash_report)
         virtnet_init_default_rss(vi);
 
     /* serialize netdev register + virtio_device_ready() with ndo_open() */
     rtnl_lock();
 
     err = register_netdevice(dev);
     if (err) {
         pr_debug("virtio_net: registering device failed\n");
         rtnl_unlock();
         goto free_failover;
     }
 
     virtio_device_ready(vdev);
 
     rtnl_unlock();
 
     err = virtnet_cpu_notif_add(vi);
     if (err) {
         pr_debug("virtio_net: registering cpu notifier failed\n");
         goto free_unregister_netdev;
     }
 
     virtnet_set_queues(vi, vi->curr_queue_pairs);
 
     /* Assume link up if device can't report link status,
        otherwise get link status from config. */
     netif_carrier_off(dev);
     if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
         schedule_work(&vi->config_work);
     } else {
         vi->status = VIRTIO_NET_S_LINK_UP;
         virtnet_update_settings(vi);
         netif_carrier_on(dev);
     }
 
     for (i = 0; i < ARRAY_SIZE(guest_offloads); i++)
         if (virtio_has_feature(vi->vdev, guest_offloads[i]))
             set_bit(guest_offloads[i], &vi->guest_offloads);
     vi->guest_offloads_capable = vi->guest_offloads;
 
     pr_debug("virtnet: registered device %s with %d RX and TX vq's\n",
          dev->name, max_queue_pairs);
 
     return 0;
 
 free_unregister_netdev:
     virtio_reset_device(vdev);
 
     unregister_netdev(dev);
 free_failover:
     net_failover_destroy(vi->failover);
 free_vqs:
     cancel_delayed_work_sync(&vi->refill);
     free_receive_page_frags(vi);
     virtnet_del_vqs(vi);
 free:
     free_netdev(dev);
     return err;
 }
 
 static void remove_vq_common(struct virtnet_info *vi)
 {
     virtio_reset_device(vi->vdev);
 
     /* Free unused buffers in both send and recv, if any. */
     free_unused_bufs(vi);
 
     free_receive_bufs(vi);
 
     free_receive_page_frags(vi);
 
     virtnet_del_vqs(vi);
 }
 
 static void virtnet_remove(struct virtio_device *vdev)
 {
     struct virtnet_info *vi = vdev->priv;
 
     virtnet_cpu_notif_remove(vi);
 
     /* Make sure no work handler is accessing the device. */
     flush_work(&vi->config_work);
 
     unregister_netdev(vi->dev);
 
     net_failover_destroy(vi->failover);
 
     remove_vq_common(vi);
 
     free_netdev(vi->dev);
 }
 
 static __maybe_unused int virtnet_freeze(struct virtio_device *vdev)
 {
     struct virtnet_info *vi = vdev->priv;
 
     virtnet_cpu_notif_remove(vi);
     virtnet_freeze_down(vdev);
     remove_vq_common(vi);
 
     return 0;
 }
 
 static __maybe_unused int virtnet_restore(struct virtio_device *vdev)
 {
     struct virtnet_info *vi = vdev->priv;
     int err;
 
     err = virtnet_restore_up(vdev);
     if (err)
         return err;
     virtnet_set_queues(vi, vi->curr_queue_pairs);
 
     err = virtnet_cpu_notif_add(vi);
     if (err) {
         virtnet_freeze_down(vdev);
         remove_vq_common(vi);
         return err;
     }
 
     return 0;
 }
 
 static struct virtio_device_id id_table[] = {
     { VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },
     { 0 },
 };
 
 #define VIRTNET_FEATURES \
     VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM, \
     VIRTIO_NET_F_MAC, \
     VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6, \
     VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6, \
     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_MQ, \
     VIRTIO_NET_F_CTRL_MAC_ADDR, \
     VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
     VIRTIO_NET_F_SPEED_DUPLEX, VIRTIO_NET_F_STANDBY, \
     VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT, VIRTIO_NET_F_NOTF_COAL
 
 static unsigned int features[] = {
     VIRTNET_FEATURES,
 };
 
 static unsigned int features_legacy[] = {
     VIRTNET_FEATURES,
     VIRTIO_NET_F_GSO,
     VIRTIO_F_ANY_LAYOUT,
 };
 
 static struct virtio_driver virtio_net_driver = {
     .feature_table = features,
     .feature_table_size = ARRAY_SIZE(features),
     .feature_table_legacy = features_legacy,
     .feature_table_size_legacy = ARRAY_SIZE(features_legacy),
     .driver.name =  KBUILD_MODNAME,
     .driver.owner = THIS_MODULE,
     .id_table = id_table,
     .validate = virtnet_validate,
     .probe =    virtnet_probe,
     .remove =   virtnet_remove,
     .config_changed = virtnet_config_changed,
 #ifdef CONFIG_PM_SLEEP
     .freeze =   virtnet_freeze,
     .restore =  virtnet_restore,
 #endif
 };
 
 static __init int virtio_net_driver_init(void)
 {
     int ret;
 
     ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "virtio/net:online",
                       virtnet_cpu_online,
                       virtnet_cpu_down_prep);
     if (ret < 0)
         goto out;
     virtionet_online = ret;
     ret = cpuhp_setup_state_multi(CPUHP_VIRT_NET_DEAD, "virtio/net:dead",
                       NULL, virtnet_cpu_dead);
     if (ret)
         goto err_dead;
     ret = register_virtio_driver(&virtio_net_driver);
     if (ret)
         goto err_virtio;
     return 0;
 err_virtio:
     cpuhp_remove_multi_state(CPUHP_VIRT_NET_DEAD);
 err_dead:
     cpuhp_remove_multi_state(virtionet_online);
 out:
     return ret;
 }
 module_init(virtio_net_driver_init);
 
 static __exit void virtio_net_driver_exit(void)
 {
     unregister_virtio_driver(&virtio_net_driver);
     cpuhp_remove_multi_state(CPUHP_VIRT_NET_DEAD);
     cpuhp_remove_multi_state(virtionet_online);
 }
 module_exit(virtio_net_driver_exit);
 
 MODULE_DEVICE_TABLE(virtio, id_table);
 MODULE_DESCRIPTION("Virtio network driver");
 MODULE_LICENSE("GPL");