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31 results

generic_mpih-mul1.c

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    • Dmitry Kasatkin's avatar
      cdec9cb5
      crypto: GnuPG based MPI lib - source files (part 1) · cdec9cb5
      Dmitry Kasatkin authored
      
      Adds the multi-precision-integer maths library which was originally taken
      from GnuPG and ported to the kernel by (among others) David Howells.
      This version is taken from Fedora kernel 2.6.32-71.14.1.el6.
      The difference is that checkpatch reported errors and warnings have been fixed.
      
      This library is used to implemenet RSA digital signature verification
      used in IMA/EVM integrity protection subsystem.
      
      Due to patch size limitation, the patch is divided into 4 parts.
      
      Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
      cdec9cb5
      History
      crypto: GnuPG based MPI lib - source files (part 1)
      Dmitry Kasatkin authored
      
      Adds the multi-precision-integer maths library which was originally taken
      from GnuPG and ported to the kernel by (among others) David Howells.
      This version is taken from Fedora kernel 2.6.32-71.14.1.el6.
      The difference is that checkpatch reported errors and warnings have been fixed.
      
      This library is used to implemenet RSA digital signature verification
      used in IMA/EVM integrity protection subsystem.
      
      Due to patch size limitation, the patch is divided into 4 parts.
      
      Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
    vsock.c 21.03 KiB
    // SPDX-License-Identifier: GPL-2.0-only
    /*
     * vhost transport for vsock
     *
     * Copyright (C) 2013-2015 Red Hat, Inc.
     * Author: Asias He <asias@redhat.com>
     *         Stefan Hajnoczi <stefanha@redhat.com>
     */
    #include <linux/miscdevice.h>
    #include <linux/atomic.h>
    #include <linux/module.h>
    #include <linux/mutex.h>
    #include <linux/vmalloc.h>
    #include <net/sock.h>
    #include <linux/virtio_vsock.h>
    #include <linux/vhost.h>
    #include <linux/hashtable.h>
    
    #include <net/af_vsock.h>
    #include "vhost.h"
    
    #define VHOST_VSOCK_DEFAULT_HOST_CID	2
    /* Max number of bytes transferred before requeueing the job.
     * Using this limit prevents one virtqueue from starving others. */
    #define VHOST_VSOCK_WEIGHT 0x80000
    /* Max number of packets transferred before requeueing the job.
     * Using this limit prevents one virtqueue from starving others with
     * small pkts.
     */
    #define VHOST_VSOCK_PKT_WEIGHT 256
    
    enum {
    	VHOST_VSOCK_FEATURES = VHOST_FEATURES,
    };
    
    /* Used to track all the vhost_vsock instances on the system. */
    static DEFINE_MUTEX(vhost_vsock_mutex);
    static DEFINE_READ_MOSTLY_HASHTABLE(vhost_vsock_hash, 8);
    
    struct vhost_vsock {
    	struct vhost_dev dev;
    	struct vhost_virtqueue vqs[2];
    
    	/* Link to global vhost_vsock_hash, writes use vhost_vsock_mutex */
    	struct hlist_node hash;
    
    	struct vhost_work send_pkt_work;
    	spinlock_t send_pkt_list_lock;
    	struct list_head send_pkt_list;	/* host->guest pending packets */
    
    	atomic_t queued_replies;
    
    	u32 guest_cid;
    };
    
    static u32 vhost_transport_get_local_cid(void)
    {
    	return VHOST_VSOCK_DEFAULT_HOST_CID;
    }
    
    /* Callers that dereference the return value must hold vhost_vsock_mutex or the
     * RCU read lock.
     */
    static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
    {
    	struct vhost_vsock *vsock;
    
    	hash_for_each_possible_rcu(vhost_vsock_hash, vsock, hash, guest_cid) {
    		u32 other_cid = vsock->guest_cid;
    
    		/* Skip instances that have no CID yet */
    		if (other_cid == 0)
    			continue;
    
    		if (other_cid == guest_cid)
    			return vsock;
    
    	}
    
    	return NULL;
    }
    
    static void
    vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
    			    struct vhost_virtqueue *vq)
    {
    	struct vhost_virtqueue *tx_vq = &vsock->vqs[VSOCK_VQ_TX];
    	int pkts = 0, total_len = 0;
    	bool added = false;
    	bool restart_tx = false;
    
    	mutex_lock(&vq->mutex);
    
    	if (!vhost_vq_get_backend(vq))
    		goto out;
    
    	/* Avoid further vmexits, we're already processing the virtqueue */
    	vhost_disable_notify(&vsock->dev, vq);
    
    	do {
    		struct virtio_vsock_pkt *pkt;
    		struct iov_iter iov_iter;
    		unsigned out, in;
    		size_t nbytes;
    		size_t iov_len, payload_len;
    		int head;
    
    		spin_lock_bh(&vsock->send_pkt_list_lock);
    		if (list_empty(&vsock->send_pkt_list)) {
    			spin_unlock_bh(&vsock->send_pkt_list_lock);
    			vhost_enable_notify(&vsock->dev, vq);
    			break;
    		}
    
    		pkt = list_first_entry(&vsock->send_pkt_list,
    				       struct virtio_vsock_pkt, list);
    		list_del_init(&pkt->list);
    		spin_unlock_bh(&vsock->send_pkt_list_lock);
    
    		head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
    					 &out, &in, NULL, NULL);
    		if (head < 0) {
    			spin_lock_bh(&vsock->send_pkt_list_lock);
    			list_add(&pkt->list, &vsock->send_pkt_list);
    			spin_unlock_bh(&vsock->send_pkt_list_lock);
    			break;
    		}
    
    		if (head == vq->num) {
    			spin_lock_bh(&vsock->send_pkt_list_lock);
    			list_add(&pkt->list, &vsock->send_pkt_list);
    			spin_unlock_bh(&vsock->send_pkt_list_lock);
    
    			/* We cannot finish yet if more buffers snuck in while
    			 * re-enabling notify.
    			 */
    			if (unlikely(vhost_enable_notify(&vsock->dev, vq))) {
    				vhost_disable_notify(&vsock->dev, vq);
    				continue;
    			}
    			break;
    		}
    
    		if (out) {
    			virtio_transport_free_pkt(pkt);
    			vq_err(vq, "Expected 0 output buffers, got %u\n", out);
    			break;
    		}
    
    		iov_len = iov_length(&vq->iov[out], in);
    		if (iov_len < sizeof(pkt->hdr)) {
    			virtio_transport_free_pkt(pkt);
    			vq_err(vq, "Buffer len [%zu] too small\n", iov_len);
    			break;
    		}
    
    		iov_iter_init(&iov_iter, READ, &vq->iov[out], in, iov_len);
    		payload_len = pkt->len - pkt->off;
    
    		/* If the packet is greater than the space available in the
    		 * buffer, we split it using multiple buffers.
    		 */
    		if (payload_len > iov_len - sizeof(pkt->hdr))
    			payload_len = iov_len - sizeof(pkt->hdr);
    
    		/* Set the correct length in the header */
    		pkt->hdr.len = cpu_to_le32(payload_len);
    
    		nbytes = copy_to_iter(&pkt->hdr, sizeof(pkt->hdr), &iov_iter);
    		if (nbytes != sizeof(pkt->hdr)) {
    			virtio_transport_free_pkt(pkt);
    			vq_err(vq, "Faulted on copying pkt hdr\n");
    			break;
    		}
    
    		nbytes = copy_to_iter(pkt->buf + pkt->off, payload_len,
    				      &iov_iter);
    		if (nbytes != payload_len) {
    			virtio_transport_free_pkt(pkt);
    			vq_err(vq, "Faulted on copying pkt buf\n");
    			break;
    		}
    
    		vhost_add_used(vq, head, sizeof(pkt->hdr) + payload_len);
    		added = true;
    
    		/* Deliver to monitoring devices all correctly transmitted
    		 * packets.
    		 */
    		virtio_transport_deliver_tap_pkt(pkt);
    
    		pkt->off += payload_len;
    		total_len += payload_len;
    
    		/* If we didn't send all the payload we can requeue the packet
    		 * to send it with the next available buffer.
    		 */
    		if (pkt->off < pkt->len) {
    			spin_lock_bh(&vsock->send_pkt_list_lock);
    			list_add(&pkt->list, &vsock->send_pkt_list);
    			spin_unlock_bh(&vsock->send_pkt_list_lock);
    		} else {
    			if (pkt->reply) {
    				int val;
    
    				val = atomic_dec_return(&vsock->queued_replies);
    
    				/* Do we have resources to resume tx
    				 * processing?
    				 */
    				if (val + 1 == tx_vq->num)
    					restart_tx = true;
    			}
    
    			virtio_transport_free_pkt(pkt);
    		}
    	} while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
    	if (added)
    		vhost_signal(&vsock->dev, vq);
    
    out:
    	mutex_unlock(&vq->mutex);
    
    	if (restart_tx)
    		vhost_poll_queue(&tx_vq->poll);
    }
    
    static void vhost_transport_send_pkt_work(struct vhost_work *work)
    {
    	struct vhost_virtqueue *vq;
    	struct vhost_vsock *vsock;
    
    	vsock = container_of(work, struct vhost_vsock, send_pkt_work);
    	vq = &vsock->vqs[VSOCK_VQ_RX];
    
    	vhost_transport_do_send_pkt(vsock, vq);
    }
    
    static int
    vhost_transport_send_pkt(struct virtio_vsock_pkt *pkt)
    {
    	struct vhost_vsock *vsock;
    	int len = pkt->len;
    
    	rcu_read_lock();
    
    	/* Find the vhost_vsock according to guest context id  */
    	vsock = vhost_vsock_get(le64_to_cpu(pkt->hdr.dst_cid));
    	if (!vsock) {
    		rcu_read_unlock();
    		virtio_transport_free_pkt(pkt);
    		return -ENODEV;
    	}
    
    	if (pkt->reply)
    		atomic_inc(&vsock->queued_replies);
    
    	spin_lock_bh(&vsock->send_pkt_list_lock);
    	list_add_tail(&pkt->list, &vsock->send_pkt_list);
    	spin_unlock_bh(&vsock->send_pkt_list_lock);
    
    	vhost_work_queue(&vsock->dev, &vsock->send_pkt_work);
    
    	rcu_read_unlock();
    	return len;
    }
    
    static int
    vhost_transport_cancel_pkt(struct vsock_sock *vsk)
    {
    	struct vhost_vsock *vsock;
    	struct virtio_vsock_pkt *pkt, *n;
    	int cnt = 0;
    	int ret = -ENODEV;
    	LIST_HEAD(freeme);
    
    	rcu_read_lock();
    
    	/* Find the vhost_vsock according to guest context id  */
    	vsock = vhost_vsock_get(vsk->remote_addr.svm_cid);
    	if (!vsock)
    		goto out;
    
    	spin_lock_bh(&vsock->send_pkt_list_lock);
    	list_for_each_entry_safe(pkt, n, &vsock->send_pkt_list, list) {
    		if (pkt->vsk != vsk)
    			continue;
    		list_move(&pkt->list, &freeme);
    	}
    	spin_unlock_bh(&vsock->send_pkt_list_lock);
    
    	list_for_each_entry_safe(pkt, n, &freeme, list) {
    		if (pkt->reply)
    			cnt++;
    		list_del(&pkt->list);
    		virtio_transport_free_pkt(pkt);
    	}
    
    	if (cnt) {
    		struct vhost_virtqueue *tx_vq = &vsock->vqs[VSOCK_VQ_TX];
    		int new_cnt;
    
    		new_cnt = atomic_sub_return(cnt, &vsock->queued_replies);
    		if (new_cnt + cnt >= tx_vq->num && new_cnt < tx_vq->num)
    			vhost_poll_queue(&tx_vq->poll);
    	}
    
    	ret = 0;
    out:
    	rcu_read_unlock();
    	return ret;
    }
    
    static struct virtio_vsock_pkt *
    vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
    		      unsigned int out, unsigned int in)
    {
    	struct virtio_vsock_pkt *pkt;
    	struct iov_iter iov_iter;
    	size_t nbytes;
    	size_t len;
    
    	if (in != 0) {
    		vq_err(vq, "Expected 0 input buffers, got %u\n", in);
    		return NULL;
    	}
    
    	pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
    	if (!pkt)
    		return NULL;
    
    	len = iov_length(vq->iov, out);
    	iov_iter_init(&iov_iter, WRITE, vq->iov, out, len);
    
    	nbytes = copy_from_iter(&pkt->hdr, sizeof(pkt->hdr), &iov_iter);
    	if (nbytes != sizeof(pkt->hdr)) {
    		vq_err(vq, "Expected %zu bytes for pkt->hdr, got %zu bytes\n",
    		       sizeof(pkt->hdr), nbytes);
    		kfree(pkt);
    		return NULL;
    	}
    
    	if (le16_to_cpu(pkt->hdr.type) == VIRTIO_VSOCK_TYPE_STREAM)
    		pkt->len = le32_to_cpu(pkt->hdr.len);
    
    	/* No payload */
    	if (!pkt->len)
    		return pkt;
    
    	/* The pkt is too big */
    	if (pkt->len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) {
    		kfree(pkt);
    		return NULL;
    	}
    
    	pkt->buf = kmalloc(pkt->len, GFP_KERNEL);
    	if (!pkt->buf) {
    		kfree(pkt);
    		return NULL;
    	}
    
    	pkt->buf_len = pkt->len;
    
    	nbytes = copy_from_iter(pkt->buf, pkt->len, &iov_iter);
    	if (nbytes != pkt->len) {
    		vq_err(vq, "Expected %u byte payload, got %zu bytes\n",
    		       pkt->len, nbytes);
    		virtio_transport_free_pkt(pkt);
    		return NULL;
    	}
    
    	return pkt;
    }
    
    /* Is there space left for replies to rx packets? */
    static bool vhost_vsock_more_replies(struct vhost_vsock *vsock)
    {
    	struct vhost_virtqueue *vq = &vsock->vqs[VSOCK_VQ_TX];
    	int val;
    
    	smp_rmb(); /* paired with atomic_inc() and atomic_dec_return() */
    	val = atomic_read(&vsock->queued_replies);
    
    	return val < vq->num;
    }
    
    static struct virtio_transport vhost_transport = {
    	.transport = {
    		.module                   = THIS_MODULE,
    
    		.get_local_cid            = vhost_transport_get_local_cid,
    
    		.init                     = virtio_transport_do_socket_init,
    		.destruct                 = virtio_transport_destruct,
    		.release                  = virtio_transport_release,
    		.connect                  = virtio_transport_connect,
    		.shutdown                 = virtio_transport_shutdown,
    		.cancel_pkt               = vhost_transport_cancel_pkt,
    
    		.dgram_enqueue            = virtio_transport_dgram_enqueue,
    		.dgram_dequeue            = virtio_transport_dgram_dequeue,
    		.dgram_bind               = virtio_transport_dgram_bind,
    		.dgram_allow              = virtio_transport_dgram_allow,
    
    		.stream_enqueue           = virtio_transport_stream_enqueue,
    		.stream_dequeue           = virtio_transport_stream_dequeue,
    		.stream_has_data          = virtio_transport_stream_has_data,
    		.stream_has_space         = virtio_transport_stream_has_space,
    		.stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
    		.stream_is_active         = virtio_transport_stream_is_active,
    		.stream_allow             = virtio_transport_stream_allow,
    
    		.notify_poll_in           = virtio_transport_notify_poll_in,
    		.notify_poll_out          = virtio_transport_notify_poll_out,
    		.notify_recv_init         = virtio_transport_notify_recv_init,
    		.notify_recv_pre_block    = virtio_transport_notify_recv_pre_block,
    		.notify_recv_pre_dequeue  = virtio_transport_notify_recv_pre_dequeue,
    		.notify_recv_post_dequeue = virtio_transport_notify_recv_post_dequeue,
    		.notify_send_init         = virtio_transport_notify_send_init,
    		.notify_send_pre_block    = virtio_transport_notify_send_pre_block,
    		.notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
    		.notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
    		.notify_buffer_size       = virtio_transport_notify_buffer_size,
    
    	},
    
    	.send_pkt = vhost_transport_send_pkt,
    };
    
    static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
    {
    	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
    						  poll.work);
    	struct vhost_vsock *vsock = container_of(vq->dev, struct vhost_vsock,
    						 dev);
    	struct virtio_vsock_pkt *pkt;
    	int head, pkts = 0, total_len = 0;
    	unsigned int out, in;
    	bool added = false;
    
    	mutex_lock(&vq->mutex);
    
    	if (!vhost_vq_get_backend(vq))
    		goto out;
    
    	vhost_disable_notify(&vsock->dev, vq);
    	do {
    		u32 len;
    
    		if (!vhost_vsock_more_replies(vsock)) {
    			/* Stop tx until the device processes already
    			 * pending replies.  Leave tx virtqueue
    			 * callbacks disabled.
    			 */
    			goto no_more_replies;
    		}
    
    		head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
    					 &out, &in, NULL, NULL);
    		if (head < 0)
    			break;
    
    		if (head == vq->num) {
    			if (unlikely(vhost_enable_notify(&vsock->dev, vq))) {
    				vhost_disable_notify(&vsock->dev, vq);
    				continue;
    			}
    			break;
    		}
    
    		pkt = vhost_vsock_alloc_pkt(vq, out, in);
    		if (!pkt) {
    			vq_err(vq, "Faulted on pkt\n");
    			continue;
    		}
    
    		len = pkt->len;
    
    		/* Deliver to monitoring devices all received packets */
    		virtio_transport_deliver_tap_pkt(pkt);
    
    		/* Only accept correctly addressed packets */
    		if (le64_to_cpu(pkt->hdr.src_cid) == vsock->guest_cid &&
    		    le64_to_cpu(pkt->hdr.dst_cid) ==
    		    vhost_transport_get_local_cid())
    			virtio_transport_recv_pkt(&vhost_transport, pkt);
    		else
    			virtio_transport_free_pkt(pkt);
    
    		len += sizeof(pkt->hdr);
    		vhost_add_used(vq, head, len);
    		total_len += len;
    		added = true;
    	} while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
    
    no_more_replies:
    	if (added)
    		vhost_signal(&vsock->dev, vq);
    
    out:
    	mutex_unlock(&vq->mutex);
    }
    
    static void vhost_vsock_handle_rx_kick(struct vhost_work *work)
    {
    	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
    						poll.work);
    	struct vhost_vsock *vsock = container_of(vq->dev, struct vhost_vsock,
    						 dev);
    
    	vhost_transport_do_send_pkt(vsock, vq);
    }
    
    static int vhost_vsock_start(struct vhost_vsock *vsock)
    {
    	struct vhost_virtqueue *vq;
    	size_t i;
    	int ret;
    
    	mutex_lock(&vsock->dev.mutex);
    
    	ret = vhost_dev_check_owner(&vsock->dev);
    	if (ret)
    		goto err;
    
    	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
    		vq = &vsock->vqs[i];
    
    		mutex_lock(&vq->mutex);
    
    		if (!vhost_vq_access_ok(vq)) {
    			ret = -EFAULT;
    			goto err_vq;
    		}
    
    		if (!vhost_vq_get_backend(vq)) {
    			vhost_vq_set_backend(vq, vsock);
    			ret = vhost_vq_init_access(vq);
    			if (ret)
    				goto err_vq;
    		}
    
    		mutex_unlock(&vq->mutex);
    	}
    
    	/* Some packets may have been queued before the device was started,
    	 * let's kick the send worker to send them.
    	 */
    	vhost_work_queue(&vsock->dev, &vsock->send_pkt_work);
    
    	mutex_unlock(&vsock->dev.mutex);
    	return 0;
    
    err_vq:
    	vhost_vq_set_backend(vq, NULL);
    	mutex_unlock(&vq->mutex);
    
    	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
    		vq = &vsock->vqs[i];
    
    		mutex_lock(&vq->mutex);
    		vhost_vq_set_backend(vq, NULL);
    		mutex_unlock(&vq->mutex);
    	}
    err:
    	mutex_unlock(&vsock->dev.mutex);
    	return ret;
    }
    
    static int vhost_vsock_stop(struct vhost_vsock *vsock)
    {
    	size_t i;
    	int ret;
    
    	mutex_lock(&vsock->dev.mutex);
    
    	ret = vhost_dev_check_owner(&vsock->dev);
    	if (ret)
    		goto err;
    
    	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
    		struct vhost_virtqueue *vq = &vsock->vqs[i];
    
    		mutex_lock(&vq->mutex);
    		vhost_vq_set_backend(vq, NULL);
    		mutex_unlock(&vq->mutex);
    	}
    
    err:
    	mutex_unlock(&vsock->dev.mutex);
    	return ret;
    }
    
    static void vhost_vsock_free(struct vhost_vsock *vsock)
    {
    	kvfree(vsock);
    }
    
    static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
    {
    	struct vhost_virtqueue **vqs;
    	struct vhost_vsock *vsock;
    	int ret;
    
    	/* This struct is large and allocation could fail, fall back to vmalloc
    	 * if there is no other way.
    	 */
    	vsock = kvmalloc(sizeof(*vsock), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
    	if (!vsock)
    		return -ENOMEM;
    
    	vqs = kmalloc_array(ARRAY_SIZE(vsock->vqs), sizeof(*vqs), GFP_KERNEL);
    	if (!vqs) {
    		ret = -ENOMEM;
    		goto out;
    	}
    
    	vsock->guest_cid = 0; /* no CID assigned yet */
    
    	atomic_set(&vsock->queued_replies, 0);
    
    	vqs[VSOCK_VQ_TX] = &vsock->vqs[VSOCK_VQ_TX];
    	vqs[VSOCK_VQ_RX] = &vsock->vqs[VSOCK_VQ_RX];
    	vsock->vqs[VSOCK_VQ_TX].handle_kick = vhost_vsock_handle_tx_kick;
    	vsock->vqs[VSOCK_VQ_RX].handle_kick = vhost_vsock_handle_rx_kick;
    
    	vhost_dev_init(&vsock->dev, vqs, ARRAY_SIZE(vsock->vqs),
    		       UIO_MAXIOV, VHOST_VSOCK_PKT_WEIGHT,
    		       VHOST_VSOCK_WEIGHT, NULL);
    
    	file->private_data = vsock;
    	spin_lock_init(&vsock->send_pkt_list_lock);
    	INIT_LIST_HEAD(&vsock->send_pkt_list);
    	vhost_work_init(&vsock->send_pkt_work, vhost_transport_send_pkt_work);
    	return 0;
    
    out:
    	vhost_vsock_free(vsock);
    	return ret;
    }
    
    static void vhost_vsock_flush(struct vhost_vsock *vsock)
    {
    	int i;
    
    	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++)
    		if (vsock->vqs[i].handle_kick)
    			vhost_poll_flush(&vsock->vqs[i].poll);
    	vhost_work_flush(&vsock->dev, &vsock->send_pkt_work);
    }
    
    static void vhost_vsock_reset_orphans(struct sock *sk)
    {
    	struct vsock_sock *vsk = vsock_sk(sk);
    
    	/* vmci_transport.c doesn't take sk_lock here either.  At least we're
    	 * under vsock_table_lock so the sock cannot disappear while we're
    	 * executing.
    	 */
    
    	/* If the peer is still valid, no need to reset connection */
    	if (vhost_vsock_get(vsk->remote_addr.svm_cid))
    		return;
    
    	/* If the close timeout is pending, let it expire.  This avoids races
    	 * with the timeout callback.
    	 */
    	if (vsk->close_work_scheduled)
    		return;
    
    	sock_set_flag(sk, SOCK_DONE);
    	vsk->peer_shutdown = SHUTDOWN_MASK;
    	sk->sk_state = SS_UNCONNECTED;
    	sk->sk_err = ECONNRESET;
    	sk->sk_error_report(sk);
    }
    
    static int vhost_vsock_dev_release(struct inode *inode, struct file *file)
    {
    	struct vhost_vsock *vsock = file->private_data;
    
    	mutex_lock(&vhost_vsock_mutex);
    	if (vsock->guest_cid)
    		hash_del_rcu(&vsock->hash);
    	mutex_unlock(&vhost_vsock_mutex);
    
    	/* Wait for other CPUs to finish using vsock */
    	synchronize_rcu();
    
    	/* Iterating over all connections for all CIDs to find orphans is
    	 * inefficient.  Room for improvement here. */
    	vsock_for_each_connected_socket(vhost_vsock_reset_orphans);
    
    	vhost_vsock_stop(vsock);
    	vhost_vsock_flush(vsock);
    	vhost_dev_stop(&vsock->dev);
    
    	spin_lock_bh(&vsock->send_pkt_list_lock);
    	while (!list_empty(&vsock->send_pkt_list)) {
    		struct virtio_vsock_pkt *pkt;
    
    		pkt = list_first_entry(&vsock->send_pkt_list,
    				struct virtio_vsock_pkt, list);
    		list_del_init(&pkt->list);
    		virtio_transport_free_pkt(pkt);
    	}
    	spin_unlock_bh(&vsock->send_pkt_list_lock);
    
    	vhost_dev_cleanup(&vsock->dev);
    	kfree(vsock->dev.vqs);
    	vhost_vsock_free(vsock);
    	return 0;
    }
    
    static int vhost_vsock_set_cid(struct vhost_vsock *vsock, u64 guest_cid)
    {
    	struct vhost_vsock *other;
    
    	/* Refuse reserved CIDs */
    	if (guest_cid <= VMADDR_CID_HOST ||
    	    guest_cid == U32_MAX)
    		return -EINVAL;
    
    	/* 64-bit CIDs are not yet supported */
    	if (guest_cid > U32_MAX)
    		return -EINVAL;
    
    	/* Refuse if CID is assigned to the guest->host transport (i.e. nested
    	 * VM), to make the loopback work.
    	 */
    	if (vsock_find_cid(guest_cid))
    		return -EADDRINUSE;
    
    	/* Refuse if CID is already in use */
    	mutex_lock(&vhost_vsock_mutex);
    	other = vhost_vsock_get(guest_cid);
    	if (other && other != vsock) {
    		mutex_unlock(&vhost_vsock_mutex);
    		return -EADDRINUSE;
    	}
    
    	if (vsock->guest_cid)
    		hash_del_rcu(&vsock->hash);
    
    	vsock->guest_cid = guest_cid;
    	hash_add_rcu(vhost_vsock_hash, &vsock->hash, vsock->guest_cid);
    	mutex_unlock(&vhost_vsock_mutex);
    
    	return 0;
    }
    
    static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features)
    {
    	struct vhost_virtqueue *vq;
    	int i;
    
    	if (features & ~VHOST_VSOCK_FEATURES)
    		return -EOPNOTSUPP;
    
    	mutex_lock(&vsock->dev.mutex);
    	if ((features & (1 << VHOST_F_LOG_ALL)) &&
    	    !vhost_log_access_ok(&vsock->dev)) {
    		mutex_unlock(&vsock->dev.mutex);
    		return -EFAULT;
    	}
    
    	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
    		vq = &vsock->vqs[i];
    		mutex_lock(&vq->mutex);
    		vq->acked_features = features;
    		mutex_unlock(&vq->mutex);
    	}
    	mutex_unlock(&vsock->dev.mutex);
    	return 0;
    }
    
    static long vhost_vsock_dev_ioctl(struct file *f, unsigned int ioctl,
    				  unsigned long arg)
    {
    	struct vhost_vsock *vsock = f->private_data;
    	void __user *argp = (void __user *)arg;
    	u64 guest_cid;
    	u64 features;
    	int start;
    	int r;
    
    	switch (ioctl) {
    	case VHOST_VSOCK_SET_GUEST_CID:
    		if (copy_from_user(&guest_cid, argp, sizeof(guest_cid)))
    			return -EFAULT;
    		return vhost_vsock_set_cid(vsock, guest_cid);
    	case VHOST_VSOCK_SET_RUNNING:
    		if (copy_from_user(&start, argp, sizeof(start)))
    			return -EFAULT;
    		if (start)
    			return vhost_vsock_start(vsock);
    		else
    			return vhost_vsock_stop(vsock);
    	case VHOST_GET_FEATURES:
    		features = VHOST_VSOCK_FEATURES;
    		if (copy_to_user(argp, &features, sizeof(features)))
    			return -EFAULT;
    		return 0;
    	case VHOST_SET_FEATURES:
    		if (copy_from_user(&features, argp, sizeof(features)))
    			return -EFAULT;
    		return vhost_vsock_set_features(vsock, features);
    	default:
    		mutex_lock(&vsock->dev.mutex);
    		r = vhost_dev_ioctl(&vsock->dev, ioctl, argp);
    		if (r == -ENOIOCTLCMD)
    			r = vhost_vring_ioctl(&vsock->dev, ioctl, argp);
    		else
    			vhost_vsock_flush(vsock);
    		mutex_unlock(&vsock->dev.mutex);
    		return r;
    	}
    }
    
    static const struct file_operations vhost_vsock_fops = {
    	.owner          = THIS_MODULE,
    	.open           = vhost_vsock_dev_open,
    	.release        = vhost_vsock_dev_release,
    	.llseek		= noop_llseek,
    	.unlocked_ioctl = vhost_vsock_dev_ioctl,
    	.compat_ioctl   = compat_ptr_ioctl,
    };
    
    static struct miscdevice vhost_vsock_misc = {
    	.minor = VHOST_VSOCK_MINOR,
    	.name = "vhost-vsock",
    	.fops = &vhost_vsock_fops,
    };
    
    static int __init vhost_vsock_init(void)
    {
    	int ret;
    
    	ret = vsock_core_register(&vhost_transport.transport,
    				  VSOCK_TRANSPORT_F_H2G);
    	if (ret < 0)
    		return ret;
    	return misc_register(&vhost_vsock_misc);
    };
    
    static void __exit vhost_vsock_exit(void)
    {
    	misc_deregister(&vhost_vsock_misc);
    	vsock_core_unregister(&vhost_transport.transport);
    };
    
    module_init(vhost_vsock_init);
    module_exit(vhost_vsock_exit);
    MODULE_LICENSE("GPL v2");
    MODULE_AUTHOR("Asias He");
    MODULE_DESCRIPTION("vhost transport for vsock ");
    MODULE_ALIAS_MISCDEV(VHOST_VSOCK_MINOR);
    MODULE_ALIAS("devname:vhost-vsock");