// 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 (!vq->private_data) 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 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 (!vq->private_data) 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) virtio_transport_recv_pkt(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 (!vq->private_data) { vq->private_data = vsock; ret = vhost_vq_init_access(vq); if (ret) goto err_vq; } mutex_unlock(&vq->mutex); } mutex_unlock(&vsock->dev.mutex); return 0; err_vq: vq->private_data = NULL; mutex_unlock(&vq->mutex); for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) { vq = &vsock->vqs[i]; mutex_lock(&vq->mutex); vq->private_data = 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); vq->private_data = 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); 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 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 struct virtio_transport vhost_transport = { .transport = { .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, .set_buffer_size = virtio_transport_set_buffer_size, .set_min_buffer_size = virtio_transport_set_min_buffer_size, .set_max_buffer_size = virtio_transport_set_max_buffer_size, .get_buffer_size = virtio_transport_get_buffer_size, .get_min_buffer_size = virtio_transport_get_min_buffer_size, .get_max_buffer_size = virtio_transport_get_max_buffer_size, }, .send_pkt = vhost_transport_send_pkt, }; static int __init vhost_vsock_init(void) { int ret; ret = vsock_core_init(&vhost_transport.transport); 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_exit(); }; 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");