| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Jason (Hui) Wang | 5561 | 44.47% | 40 | 30.08% |
| Michael S. Tsirkin | 5491 | 43.91% | 35 | 26.32% |
| Greg Kurz | 395 | 3.16% | 4 | 3.01% |
| David L Stevens | 325 | 2.60% | 1 | 0.75% |
| Asias He | 222 | 1.78% | 4 | 3.01% |
| Tejun Heo | 133 | 1.06% | 2 | 1.50% |
| Takuya Yoshikawa | 62 | 0.50% | 1 | 0.75% |
| Igor Mammedov | 55 | 0.44% | 3 | 2.26% |
| Al Viro | 47 | 0.38% | 7 | 5.26% |
| Stefan Hajnoczi | 33 | 0.26% | 2 | 1.50% |
| Andrey Konovalov | 30 | 0.24% | 1 | 0.75% |
| Eric Biggers | 25 | 0.20% | 3 | 2.26% |
| Eric Dumazet | 18 | 0.14% | 1 | 0.75% |
| Pavel Tikhomirov | 14 | 0.11% | 1 | 0.75% |
| Arnd Bergmann | 11 | 0.09% | 1 | 0.75% |
| Halil Pasic | 10 | 0.08% | 1 | 0.75% |
| Ingo Molnar | 7 | 0.06% | 3 | 2.26% |
| Linus Torvalds | 7 | 0.06% | 1 | 0.75% |
| John Hubbard | 7 | 0.06% | 1 | 0.75% |
| Matthew Wilcox | 6 | 0.05% | 1 | 0.75% |
| Jeff Dike | 6 | 0.05% | 1 | 0.75% |
| Christoph Hellwig | 5 | 0.04% | 3 | 2.26% |
| Nadav Har'El | 5 | 0.04% | 1 | 0.75% |
| yongduan | 4 | 0.03% | 1 | 0.75% |
| Zhu Lingshan | 4 | 0.03% | 1 | 0.75% |
| Lin Yun Sheng | 3 | 0.02% | 1 | 0.75% |
| Paul E. McKenney | 3 | 0.02% | 1 | 0.75% |
| Michal Hocko | 3 | 0.02% | 1 | 0.75% |
| Kees Cook | 3 | 0.02% | 1 | 0.75% |
| Jens Freimann | 2 | 0.02% | 1 | 0.75% |
| Thomas Gleixner | 2 | 0.02% | 1 | 0.75% |
| Mauro Carvalho Chehab | 1 | 0.01% | 1 | 0.75% |
| Peng Tao | 1 | 0.01% | 1 | 0.75% |
| Ira Weiny | 1 | 0.01% | 1 | 0.75% |
| Qin Chuanyu | 1 | 0.01% | 1 | 0.75% |
| Eric Auger | 1 | 0.01% | 1 | 0.75% |
| Guennadi Liakhovetski | 1 | 0.01% | 1 | 0.75% |
| Alexey Dobriyan | 1 | 0.01% | 1 | 0.75% |
| Total | 12506 | 133 |
// SPDX-License-Identifier: GPL-2.0-only /* Copyright (C) 2009 Red Hat, Inc. * Copyright (C) 2006 Rusty Russell IBM Corporation * * Author: Michael S. Tsirkin <mst@redhat.com> * * Inspiration, some code, and most witty comments come from * Documentation/virtual/lguest/lguest.c, by Rusty Russell * * Generic code for virtio server in host kernel. */ #include <linux/eventfd.h> #include <linux/vhost.h> #include <linux/uio.h> #include <linux/mm.h> #include <linux/miscdevice.h> #include <linux/mutex.h> #include <linux/poll.h> #include <linux/file.h> #include <linux/highmem.h> #include <linux/slab.h> #include <linux/vmalloc.h> #include <linux/kthread.h> #include <linux/cgroup.h> #include <linux/module.h> #include <linux/sort.h> #include <linux/sched/mm.h> #include <linux/sched/signal.h> #include <linux/interval_tree_generic.h> #include <linux/nospec.h> #include <linux/kcov.h> #include "vhost.h" static ushort max_mem_regions = 64; module_param(max_mem_regions, ushort, 0444); MODULE_PARM_DESC(max_mem_regions, "Maximum number of memory regions in memory map. (default: 64)"); static int max_iotlb_entries = 2048; module_param(max_iotlb_entries, int, 0444); MODULE_PARM_DESC(max_iotlb_entries, "Maximum number of iotlb entries. (default: 2048)"); enum { VHOST_MEMORY_F_LOG = 0x1, }; #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num]) #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num]) #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY static void vhost_disable_cross_endian(struct vhost_virtqueue *vq) { vq->user_be = !virtio_legacy_is_little_endian(); } static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq) { vq->user_be = true; } static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq) { vq->user_be = false; } static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp) { struct vhost_vring_state s; if (vq->private_data) return -EBUSY; if (copy_from_user(&s, argp, sizeof(s))) return -EFAULT; if (s.num != VHOST_VRING_LITTLE_ENDIAN && s.num != VHOST_VRING_BIG_ENDIAN) return -EINVAL; if (s.num == VHOST_VRING_BIG_ENDIAN) vhost_enable_cross_endian_big(vq); else vhost_enable_cross_endian_little(vq); return 0; } static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx, int __user *argp) { struct vhost_vring_state s = { .index = idx, .num = vq->user_be }; if (copy_to_user(argp, &s, sizeof(s))) return -EFAULT; return 0; } static void vhost_init_is_le(struct vhost_virtqueue *vq) { /* Note for legacy virtio: user_be is initialized at reset time * according to the host endianness. If userspace does not set an * explicit endianness, the default behavior is native endian, as * expected by legacy virtio. */ vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be; } #else static void vhost_disable_cross_endian(struct vhost_virtqueue *vq) { } static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp) { return -ENOIOCTLCMD; } static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx, int __user *argp) { return -ENOIOCTLCMD; } static void vhost_init_is_le(struct vhost_virtqueue *vq) { vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || virtio_legacy_is_little_endian(); } #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */ static void vhost_reset_is_le(struct vhost_virtqueue *vq) { vhost_init_is_le(vq); } struct vhost_flush_struct { struct vhost_work work; struct completion wait_event; }; static void vhost_flush_work(struct vhost_work *work) { struct vhost_flush_struct *s; s = container_of(work, struct vhost_flush_struct, work); complete(&s->wait_event); } static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh, poll_table *pt) { struct vhost_poll *poll; poll = container_of(pt, struct vhost_poll, table); poll->wqh = wqh; add_wait_queue(wqh, &poll->wait); } static int vhost_poll_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key) { struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait); struct vhost_work *work = &poll->work; if (!(key_to_poll(key) & poll->mask)) return 0; if (!poll->dev->use_worker) work->fn(work); else vhost_poll_queue(poll); return 0; } void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn) { clear_bit(VHOST_WORK_QUEUED, &work->flags); work->fn = fn; } EXPORT_SYMBOL_GPL(vhost_work_init); /* Init poll structure */ void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, __poll_t mask, struct vhost_dev *dev) { init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup); init_poll_funcptr(&poll->table, vhost_poll_func); poll->mask = mask; poll->dev = dev; poll->wqh = NULL; vhost_work_init(&poll->work, fn); } EXPORT_SYMBOL_GPL(vhost_poll_init); /* Start polling a file. We add ourselves to file's wait queue. The caller must * keep a reference to a file until after vhost_poll_stop is called. */ int vhost_poll_start(struct vhost_poll *poll, struct file *file) { __poll_t mask; if (poll->wqh) return 0; mask = vfs_poll(file, &poll->table); if (mask) vhost_poll_wakeup(&poll->wait, 0, 0, poll_to_key(mask)); if (mask & EPOLLERR) { vhost_poll_stop(poll); return -EINVAL; } return 0; } EXPORT_SYMBOL_GPL(vhost_poll_start); /* Stop polling a file. After this function returns, it becomes safe to drop the * file reference. You must also flush afterwards. */ void vhost_poll_stop(struct vhost_poll *poll) { if (poll->wqh) { remove_wait_queue(poll->wqh, &poll->wait); poll->wqh = NULL; } } EXPORT_SYMBOL_GPL(vhost_poll_stop); void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work) { struct vhost_flush_struct flush; if (dev->worker) { init_completion(&flush.wait_event); vhost_work_init(&flush.work, vhost_flush_work); vhost_work_queue(dev, &flush.work); wait_for_completion(&flush.wait_event); } } EXPORT_SYMBOL_GPL(vhost_work_flush); /* Flush any work that has been scheduled. When calling this, don't hold any * locks that are also used by the callback. */ void vhost_poll_flush(struct vhost_poll *poll) { vhost_work_flush(poll->dev, &poll->work); } EXPORT_SYMBOL_GPL(vhost_poll_flush); void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work) { if (!dev->worker) return; if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) { /* We can only add the work to the list after we're * sure it was not in the list. * test_and_set_bit() implies a memory barrier. */ llist_add(&work->node, &dev->work_list); wake_up_process(dev->worker); } } EXPORT_SYMBOL_GPL(vhost_work_queue); /* A lockless hint for busy polling code to exit the loop */ bool vhost_has_work(struct vhost_dev *dev) { return !llist_empty(&dev->work_list); } EXPORT_SYMBOL_GPL(vhost_has_work); void vhost_poll_queue(struct vhost_poll *poll) { vhost_work_queue(poll->dev, &poll->work); } EXPORT_SYMBOL_GPL(vhost_poll_queue); static void __vhost_vq_meta_reset(struct vhost_virtqueue *vq) { int j; for (j = 0; j < VHOST_NUM_ADDRS; j++) vq->meta_iotlb[j] = NULL; } static void vhost_vq_meta_reset(struct vhost_dev *d) { int i; for (i = 0; i < d->nvqs; ++i) __vhost_vq_meta_reset(d->vqs[i]); } static void vhost_vq_reset(struct vhost_dev *dev, struct vhost_virtqueue *vq) { vq->num = 1; vq->desc = NULL; vq->avail = NULL; vq->used = NULL; vq->last_avail_idx = 0; vq->avail_idx = 0; vq->last_used_idx = 0; vq->signalled_used = 0; vq->signalled_used_valid = false; vq->used_flags = 0; vq->log_used = false; vq->log_addr = -1ull; vq->private_data = NULL; vq->acked_features = 0; vq->acked_backend_features = 0; vq->log_base = NULL; vq->error_ctx = NULL; vq->kick = NULL; vq->call_ctx = NULL; vq->log_ctx = NULL; vhost_reset_is_le(vq); vhost_disable_cross_endian(vq); vq->busyloop_timeout = 0; vq->umem = NULL; vq->iotlb = NULL; __vhost_vq_meta_reset(vq); } static int vhost_worker(void *data) { struct vhost_dev *dev = data; struct vhost_work *work, *work_next; struct llist_node *node; kthread_use_mm(dev->mm); for (;;) { /* mb paired w/ kthread_stop */ set_current_state(TASK_INTERRUPTIBLE); if (kthread_should_stop()) { __set_current_state(TASK_RUNNING); break; } node = llist_del_all(&dev->work_list); if (!node) schedule(); node = llist_reverse_order(node); /* make sure flag is seen after deletion */ smp_wmb(); llist_for_each_entry_safe(work, work_next, node, node) { clear_bit(VHOST_WORK_QUEUED, &work->flags); __set_current_state(TASK_RUNNING); kcov_remote_start_common(dev->kcov_handle); work->fn(work); kcov_remote_stop(); if (need_resched()) schedule(); } } kthread_unuse_mm(dev->mm); return 0; } static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq) { kfree(vq->indirect); vq->indirect = NULL; kfree(vq->log); vq->log = NULL; kfree(vq->heads); vq->heads = NULL; } /* Helper to allocate iovec buffers for all vqs. */ static long vhost_dev_alloc_iovecs(struct vhost_dev *dev) { struct vhost_virtqueue *vq; int i; for (i = 0; i < dev->nvqs; ++i) { vq = dev->vqs[i]; vq->indirect = kmalloc_array(UIO_MAXIOV, sizeof(*vq->indirect), GFP_KERNEL); vq->log = kmalloc_array(dev->iov_limit, sizeof(*vq->log), GFP_KERNEL); vq->heads = kmalloc_array(dev->iov_limit, sizeof(*vq->heads), GFP_KERNEL); if (!vq->indirect || !vq->log || !vq->heads) goto err_nomem; } return 0; err_nomem: for (; i >= 0; --i) vhost_vq_free_iovecs(dev->vqs[i]); return -ENOMEM; } static void vhost_dev_free_iovecs(struct vhost_dev *dev) { int i; for (i = 0; i < dev->nvqs; ++i) vhost_vq_free_iovecs(dev->vqs[i]); } bool vhost_exceeds_weight(struct vhost_virtqueue *vq, int pkts, int total_len) { struct vhost_dev *dev = vq->dev; if ((dev->byte_weight && total_len >= dev->byte_weight) || pkts >= dev->weight) { vhost_poll_queue(&vq->poll); return true; } return false; } EXPORT_SYMBOL_GPL(vhost_exceeds_weight); static size_t vhost_get_avail_size(struct vhost_virtqueue *vq, unsigned int num) { size_t event __maybe_unused = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; return sizeof(*vq->avail) + sizeof(*vq->avail->ring) * num + event; } static size_t vhost_get_used_size(struct vhost_virtqueue *vq, unsigned int num) { size_t event __maybe_unused = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; return sizeof(*vq->used) + sizeof(*vq->used->ring) * num + event; } static size_t vhost_get_desc_size(struct vhost_virtqueue *vq, unsigned int num) { return sizeof(*vq->desc) * num; } void vhost_dev_init(struct vhost_dev *dev, struct vhost_virtqueue **vqs, int nvqs, int iov_limit, int weight, int byte_weight, bool use_worker, int (*msg_handler)(struct vhost_dev *dev, struct vhost_iotlb_msg *msg)) { struct vhost_virtqueue *vq; int i; dev->vqs = vqs; dev->nvqs = nvqs; mutex_init(&dev->mutex); dev->log_ctx = NULL; dev->umem = NULL; dev->iotlb = NULL; dev->mm = NULL; dev->worker = NULL; dev->iov_limit = iov_limit; dev->weight = weight; dev->byte_weight = byte_weight; dev->use_worker = use_worker; dev->msg_handler = msg_handler; init_llist_head(&dev->work_list); init_waitqueue_head(&dev->wait); INIT_LIST_HEAD(&dev->read_list); INIT_LIST_HEAD(&dev->pending_list); spin_lock_init(&dev->iotlb_lock); for (i = 0; i < dev->nvqs; ++i) { vq = dev->vqs[i]; vq->log = NULL; vq->indirect = NULL; vq->heads = NULL; vq->dev = dev; mutex_init(&vq->mutex); vhost_vq_reset(dev, vq); if (vq->handle_kick) vhost_poll_init(&vq->poll, vq->handle_kick, EPOLLIN, dev); } } EXPORT_SYMBOL_GPL(vhost_dev_init); /* Caller should have device mutex */ long vhost_dev_check_owner(struct vhost_dev *dev) { /* Are you the owner? If not, I don't think you mean to do that */ return dev->mm == current->mm ? 0 : -EPERM; } EXPORT_SYMBOL_GPL(vhost_dev_check_owner); struct vhost_attach_cgroups_struct { struct vhost_work work; struct task_struct *owner; int ret; }; static void vhost_attach_cgroups_work(struct vhost_work *work) { struct vhost_attach_cgroups_struct *s; s = container_of(work, struct vhost_attach_cgroups_struct, work); s->ret = cgroup_attach_task_all(s->owner, current); } static int vhost_attach_cgroups(struct vhost_dev *dev) { struct vhost_attach_cgroups_struct attach; attach.owner = current; vhost_work_init(&attach.work, vhost_attach_cgroups_work); vhost_work_queue(dev, &attach.work); vhost_work_flush(dev, &attach.work); return attach.ret; } /* Caller should have device mutex */ bool vhost_dev_has_owner(struct vhost_dev *dev) { return dev->mm; } EXPORT_SYMBOL_GPL(vhost_dev_has_owner); static void vhost_attach_mm(struct vhost_dev *dev) { /* No owner, become one */ if (dev->use_worker) { dev->mm = get_task_mm(current); } else { /* vDPA device does not use worker thead, so there's * no need to hold the address space for mm. This help * to avoid deadlock in the case of mmap() which may * held the refcnt of the file and depends on release * method to remove vma. */ dev->mm = current->mm; mmgrab(dev->mm); } } static void vhost_detach_mm(struct vhost_dev *dev) { if (!dev->mm) return; if (dev->use_worker) mmput(dev->mm); else mmdrop(dev->mm); dev->mm = NULL; } /* Caller should have device mutex */ long vhost_dev_set_owner(struct vhost_dev *dev) { struct task_struct *worker; int err; /* Is there an owner already? */ if (vhost_dev_has_owner(dev)) { err = -EBUSY; goto err_mm; } vhost_attach_mm(dev); dev->kcov_handle = kcov_common_handle(); if (dev->use_worker) { worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid); if (IS_ERR(worker)) { err = PTR_ERR(worker); goto err_worker; } dev->worker = worker; wake_up_process(worker); /* avoid contributing to loadavg */ err = vhost_attach_cgroups(dev); if (err) goto err_cgroup; } err = vhost_dev_alloc_iovecs(dev); if (err) goto err_cgroup; return 0; err_cgroup: if (dev->worker) { kthread_stop(dev->worker); dev->worker = NULL; } err_worker: vhost_detach_mm(dev); dev->kcov_handle = 0; err_mm: return err; } EXPORT_SYMBOL_GPL(vhost_dev_set_owner); static struct vhost_iotlb *iotlb_alloc(void) { return vhost_iotlb_alloc(max_iotlb_entries, VHOST_IOTLB_FLAG_RETIRE); } struct vhost_iotlb *vhost_dev_reset_owner_prepare(void) { return iotlb_alloc(); } EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare); /* Caller should have device mutex */ void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_iotlb *umem) { int i; vhost_dev_cleanup(dev); dev->umem = umem; /* We don't need VQ locks below since vhost_dev_cleanup makes sure * VQs aren't running. */ for (i = 0; i < dev->nvqs; ++i) dev->vqs[i]->umem = umem; } EXPORT_SYMBOL_GPL(vhost_dev_reset_owner); void vhost_dev_stop(struct vhost_dev *dev) { int i; for (i = 0; i < dev->nvqs; ++i) { if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) { vhost_poll_stop(&dev->vqs[i]->poll); vhost_poll_flush(&dev->vqs[i]->poll); } } } EXPORT_SYMBOL_GPL(vhost_dev_stop); static void vhost_clear_msg(struct vhost_dev *dev) { struct vhost_msg_node *node, *n; spin_lock(&dev->iotlb_lock); list_for_each_entry_safe(node, n, &dev->read_list, node) { list_del(&node->node); kfree(node); } list_for_each_entry_safe(node, n, &dev->pending_list, node) { list_del(&node->node); kfree(node); } spin_unlock(&dev->iotlb_lock); } void vhost_dev_cleanup(struct vhost_dev *dev) { int i; for (i = 0; i < dev->nvqs; ++i) { if (dev->vqs[i]->error_ctx) eventfd_ctx_put(dev->vqs[i]->error_ctx); if (dev->vqs[i]->kick) fput(dev->vqs[i]->kick); if (dev->vqs[i]->call_ctx) eventfd_ctx_put(dev->vqs[i]->call_ctx); vhost_vq_reset(dev, dev->vqs[i]); } vhost_dev_free_iovecs(dev); if (dev->log_ctx) eventfd_ctx_put(dev->log_ctx); dev->log_ctx = NULL; /* No one will access memory at this point */ vhost_iotlb_free(dev->umem); dev->umem = NULL; vhost_iotlb_free(dev->iotlb); dev->iotlb = NULL; vhost_clear_msg(dev); wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM); WARN_ON(!llist_empty(&dev->work_list)); if (dev->worker) { kthread_stop(dev->worker); dev->worker = NULL; dev->kcov_handle = 0; } vhost_detach_mm(dev); } EXPORT_SYMBOL_GPL(vhost_dev_cleanup); static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz) { u64 a = addr / VHOST_PAGE_SIZE / 8; /* Make sure 64 bit math will not overflow. */ if (a > ULONG_MAX - (unsigned long)log_base || a + (unsigned long)log_base > ULONG_MAX) return false; return access_ok(log_base + a, (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8); } static bool vhost_overflow(u64 uaddr, u64 size) { /* Make sure 64 bit math will not overflow. */ return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size; } /* Caller should have vq mutex and device mutex. */ static bool vq_memory_access_ok(void __user *log_base, struct vhost_iotlb *umem, int log_all) { struct vhost_iotlb_map *map; if (!umem) return false; list_for_each_entry(map, &umem->list, link) { unsigned long a = map->addr; if (vhost_overflow(map->addr, map->size)) return false; if (!access_ok((void __user *)a, map->size)) return false; else if (log_all && !log_access_ok(log_base, map->start, map->size)) return false; } return true; } static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq, u64 addr, unsigned int size, int type) { const struct vhost_iotlb_map *map = vq->meta_iotlb[type]; if (!map) return NULL; return (void __user *)(uintptr_t)(map->addr + addr - map->start); } /* Can we switch to this memory table? */ /* Caller should have device mutex but not vq mutex */ static bool memory_access_ok(struct vhost_dev *d, struct vhost_iotlb *umem, int log_all) { int i; for (i = 0; i < d->nvqs; ++i) { bool ok; bool log; mutex_lock(&d->vqs[i]->mutex); log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL); /* If ring is inactive, will check when it's enabled. */ if (d->vqs[i]->private_data) ok = vq_memory_access_ok(d->vqs[i]->log_base, umem, log); else ok = true; mutex_unlock(&d->vqs[i]->mutex); if (!ok) return false; } return true; } static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len, struct iovec iov[], int iov_size, int access); static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to, const void *from, unsigned size) { int ret; if (!vq->iotlb) return __copy_to_user(to, from, size); else { /* This function should be called after iotlb * prefetch, which means we're sure that all vq * could be access through iotlb. So -EAGAIN should * not happen in this case. */ struct iov_iter t; void __user *uaddr = vhost_vq_meta_fetch(vq, (u64)(uintptr_t)to, size, VHOST_ADDR_USED); if (uaddr) return __copy_to_user(uaddr, from, size); ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov, ARRAY_SIZE(vq->iotlb_iov), VHOST_ACCESS_WO); if (ret < 0) goto out; iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size); ret = copy_to_iter(from, size, &t); if (ret == size) ret = 0; } out: return ret; } static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to, void __user *from, unsigned size) { int ret; if (!vq->iotlb) return __copy_from_user(to, from, size); else { /* This function should be called after iotlb * prefetch, which means we're sure that vq * could be access through iotlb. So -EAGAIN should * not happen in this case. */ void __user *uaddr = vhost_vq_meta_fetch(vq, (u64)(uintptr_t)from, size, VHOST_ADDR_DESC); struct iov_iter f; if (uaddr) return __copy_from_user(to, uaddr, size); ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov, ARRAY_SIZE(vq->iotlb_iov), VHOST_ACCESS_RO); if (ret < 0) { vq_err(vq, "IOTLB translation failure: uaddr " "%p size 0x%llx\n", from, (unsigned long long) size); goto out; } iov_iter_init(&f, READ, vq->iotlb_iov, ret, size); ret = copy_from_iter(to, size, &f); if (ret == size) ret = 0; } out: return ret; } static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq, void __user *addr, unsigned int size, int type) { int ret; ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov, ARRAY_SIZE(vq->iotlb_iov), VHOST_ACCESS_RO); if (ret < 0) { vq_err(vq, "IOTLB translation failure: uaddr " "%p size 0x%llx\n", addr, (unsigned long long) size); return NULL; } if (ret != 1 || vq->iotlb_iov[0].iov_len != size) { vq_err(vq, "Non atomic userspace memory access: uaddr " "%p size 0x%llx\n", addr, (unsigned long long) size); return NULL; } return vq->iotlb_iov[0].iov_base; } /* This function should be called after iotlb * prefetch, which means we're sure that vq * could be access through iotlb. So -EAGAIN should * not happen in this case. */ static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq, void __user *addr, unsigned int size, int type) { void __user *uaddr = vhost_vq_meta_fetch(vq, (u64)(uintptr_t)addr, size, type); if (uaddr) return uaddr; return __vhost_get_user_slow(vq, addr, size, type); } #define vhost_put_user(vq, x, ptr) \ ({ \ int ret; \ if (!vq->iotlb) { \ ret = __put_user(x, ptr); \ } else { \ __typeof__(ptr) to = \ (__typeof__(ptr)) __vhost_get_user(vq, ptr, \ sizeof(*ptr), VHOST_ADDR_USED); \ if (to != NULL) \ ret = __put_user(x, to); \ else \ ret = -EFAULT; \ } \ ret; \ }) static inline int vhost_put_avail_event(struct vhost_virtqueue *vq) { return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx), vhost_avail_event(vq)); } static inline int vhost_put_used(struct vhost_virtqueue *vq, struct vring_used_elem *head, int idx, int count) { return vhost_copy_to_user(vq, vq->used->ring + idx, head, count * sizeof(*head)); } static inline int vhost_put_used_flags(struct vhost_virtqueue *vq) { return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags), &vq->used->flags); } static inline int vhost_put_used_idx(struct vhost_virtqueue *vq) { return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx), &vq->used->idx); } #define vhost_get_user(vq, x, ptr, type) \ ({ \ int ret; \ if (!vq->iotlb) { \ ret = __get_user(x, ptr); \ } else { \ __typeof__(ptr) from = \ (__typeof__(ptr)) __vhost_get_user(vq, ptr, \ sizeof(*ptr), \ type); \ if (from != NULL) \ ret = __get_user(x, from); \ else \ ret = -EFAULT; \ } \ ret; \ }) #define vhost_get_avail(vq, x, ptr) \ vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL) #define vhost_get_used(vq, x, ptr) \ vhost_get_user(vq, x, ptr, VHOST_ADDR_USED) static void vhost_dev_lock_vqs(struct vhost_dev *d) { int i = 0; for (i = 0; i < d->nvqs; ++i) mutex_lock_nested(&d->vqs[i]->mutex, i); } static void vhost_dev_unlock_vqs(struct vhost_dev *d) { int i = 0; for (i = 0; i < d->nvqs; ++i) mutex_unlock(&d->vqs[i]->mutex); } static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq, __virtio16 *idx) { return vhost_get_avail(vq, *idx, &vq->avail->idx); } static inline int vhost_get_avail_head(struct vhost_virtqueue *vq, __virtio16 *head, int idx) { return vhost_get_avail(vq, *head, &vq->avail->ring[idx & (vq->num - 1)]); } static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq, __virtio16 *flags) { return vhost_get_avail(vq, *flags, &vq->avail->flags); } static inline int vhost_get_used_event(struct vhost_virtqueue *vq, __virtio16 *event) { return vhost_get_avail(vq, *event, vhost_used_event(vq)); } static inline int vhost_get_used_idx(struct vhost_virtqueue *vq, __virtio16 *idx) { return vhost_get_used(vq, *idx, &vq->used->idx); } static inline int vhost_get_desc(struct vhost_virtqueue *vq, struct vring_desc *desc, int idx) { return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc)); } static void vhost_iotlb_notify_vq(struct vhost_dev *d, struct vhost_iotlb_msg *msg) { struct vhost_msg_node *node, *n; spin_lock(&d->iotlb_lock); list_for_each_entry_safe(node, n, &d->pending_list, node) { struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb; if (msg->iova <= vq_msg->iova && msg->iova + msg->size - 1 >= vq_msg->iova && vq_msg->type == VHOST_IOTLB_MISS) { vhost_poll_queue(&node->vq->poll); list_del(&node->node); kfree(node); } } spin_unlock(&d->iotlb_lock); } static bool umem_access_ok(u64 uaddr, u64 size, int access) { unsigned long a = uaddr; /* Make sure 64 bit math will not overflow. */ if (vhost_overflow(uaddr, size)) return false; if ((access & VHOST_ACCESS_RO) && !access_ok((void __user *)a, size)) return false; if ((access & VHOST_ACCESS_WO) && !access_ok((void __user *)a, size)) return false; return true; } static int vhost_process_iotlb_msg(struct vhost_dev *dev, struct vhost_iotlb_msg *msg) { int ret = 0; mutex_lock(&dev->mutex); vhost_dev_lock_vqs(dev); switch (msg->type) { case VHOST_IOTLB_UPDATE: if (!dev->iotlb) { ret = -EFAULT; break; } if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) { ret = -EFAULT; break; } vhost_vq_meta_reset(dev); if (vhost_iotlb_add_range(dev->iotlb, msg->iova, msg->iova + msg->size - 1, msg->uaddr, msg->perm)) { ret = -ENOMEM; break; } vhost_iotlb_notify_vq(dev, msg); break; case VHOST_IOTLB_INVALIDATE: if (!dev->iotlb) { ret = -EFAULT; break; } vhost_vq_meta_reset(dev); vhost_iotlb_del_range(dev->iotlb, msg->iova, msg->iova + msg->size - 1); break; default: ret = -EINVAL; break; } vhost_dev_unlock_vqs(dev); mutex_unlock(&dev->mutex); return ret; } ssize_t vhost_chr_write_iter(struct vhost_dev *dev, struct iov_iter *from) { struct vhost_iotlb_msg msg; size_t offset; int type, ret; ret = copy_from_iter(&type, sizeof(type), from); if (ret != sizeof(type)) { ret = -EINVAL; goto done; } switch (type) { case VHOST_IOTLB_MSG: /* There maybe a hole after type for V1 message type, * so skip it here. */ offset = offsetof(struct vhost_msg, iotlb) - sizeof(int); break; case VHOST_IOTLB_MSG_V2: offset = sizeof(__u32); break; default: ret = -EINVAL; goto done; } iov_iter_advance(from, offset); ret = copy_from_iter(&msg, sizeof(msg), from); if (ret != sizeof(msg)) { ret = -EINVAL; goto done; } if (dev->msg_handler) ret = dev->msg_handler(dev, &msg); else ret = vhost_process_iotlb_msg(dev, &msg); if (ret) { ret = -EFAULT; goto done; } ret = (type == VHOST_IOTLB_MSG) ? sizeof(struct vhost_msg) : sizeof(struct vhost_msg_v2); done: return ret; } EXPORT_SYMBOL(vhost_chr_write_iter); __poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev, poll_table *wait) { __poll_t mask = 0; poll_wait(file, &dev->wait, wait); if (!list_empty(&dev->read_list)) mask |= EPOLLIN | EPOLLRDNORM; return mask; } EXPORT_SYMBOL(vhost_chr_poll); ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to, int noblock) { DEFINE_WAIT(wait); struct vhost_msg_node *node; ssize_t ret = 0; unsigned size = sizeof(struct vhost_msg); if (iov_iter_count(to) < size) return 0; while (1) { if (!noblock) prepare_to_wait(&dev->wait, &wait, TASK_INTERRUPTIBLE); node = vhost_dequeue_msg(dev, &dev->read_list); if (node) break; if (noblock) { ret = -EAGAIN; break; } if (signal_pending(current)) { ret = -ERESTARTSYS; break; } if (!dev->iotlb) { ret = -EBADFD; break; } schedule(); } if (!noblock) finish_wait(&dev->wait, &wait); if (node) { struct vhost_iotlb_msg *msg; void *start = &node->msg; switch (node->msg.type) { case VHOST_IOTLB_MSG: size = sizeof(node->msg); msg = &node->msg.iotlb; break; case VHOST_IOTLB_MSG_V2: size = sizeof(node->msg_v2); msg = &node->msg_v2.iotlb; break; default: BUG(); break; } ret = copy_to_iter(start, size, to); if (ret != size || msg->type != VHOST_IOTLB_MISS) { kfree(node); return ret; } vhost_enqueue_msg(dev, &dev->pending_list, node); } return ret; } EXPORT_SYMBOL_GPL(vhost_chr_read_iter); static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access) { struct vhost_dev *dev = vq->dev; struct vhost_msg_node *node; struct vhost_iotlb_msg *msg; bool v2 = vhost_backend_has_feature(vq, VHOST_BACKEND_F_IOTLB_MSG_V2); node = vhost_new_msg(vq, v2 ? VHOST_IOTLB_MSG_V2 : VHOST_IOTLB_MSG); if (!node) return -ENOMEM; if (v2) { node->msg_v2.type = VHOST_IOTLB_MSG_V2; msg = &node->msg_v2.iotlb; } else { msg = &node->msg.iotlb; } msg->type = VHOST_IOTLB_MISS; msg->iova = iova; msg->perm = access; vhost_enqueue_msg(dev, &dev->read_list, node); return 0; } static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num, vring_desc_t __user *desc, vring_avail_t __user *avail, vring_used_t __user *used) { return access_ok(desc, vhost_get_desc_size(vq, num)) && access_ok(avail, vhost_get_avail_size(vq, num)) && access_ok(used, vhost_get_used_size(vq, num)); } static void vhost_vq_meta_update(struct vhost_virtqueue *vq, const struct vhost_iotlb_map *map, int type) { int access = (type == VHOST_ADDR_USED) ? VHOST_ACCESS_WO : VHOST_ACCESS_RO; if (likely(map->perm & access)) vq->meta_iotlb[type] = map; } static bool iotlb_access_ok(struct vhost_virtqueue *vq, int access, u64 addr, u64 len, int type) { const struct vhost_iotlb_map *map; struct vhost_iotlb *umem = vq->iotlb; u64 s = 0, size, orig_addr = addr, last = addr + len - 1; if (vhost_vq_meta_fetch(vq, addr, len, type)) return true; while (len > s) { map = vhost_iotlb_itree_first(umem, addr, last); if (map == NULL || map->start > addr) { vhost_iotlb_miss(vq, addr, access); return false; } else if (!(map->perm & access)) { /* Report the possible access violation by * request another translation from userspace. */ return false; } size = map->size - addr + map->start; if (orig_addr == addr && size >= len) vhost_vq_meta_update(vq, map, type); s += size; addr += size; } return true; } int vq_meta_prefetch(struct vhost_virtqueue *vq) { unsigned int num = vq->num; if (!vq->iotlb) return 1; return iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->desc, vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) && iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->avail, vhost_get_avail_size(vq, num), VHOST_ADDR_AVAIL) && iotlb_access_ok(vq, VHOST_MAP_WO, (u64)(uintptr_t)vq->used, vhost_get_used_size(vq, num), VHOST_ADDR_USED); } EXPORT_SYMBOL_GPL(vq_meta_prefetch); /* Can we log writes? */ /* Caller should have device mutex but not vq mutex */ bool vhost_log_access_ok(struct vhost_dev *dev) { return memory_access_ok(dev, dev->umem, 1); } EXPORT_SYMBOL_GPL(vhost_log_access_ok); /* Verify access for write logging. */ /* Caller should have vq mutex and device mutex */ static bool vq_log_access_ok(struct vhost_virtqueue *vq, void __user *log_base) { return vq_memory_access_ok(log_base, vq->umem, vhost_has_feature(vq, VHOST_F_LOG_ALL)) && (!vq->log_used || log_access_ok(log_base, vq->log_addr, vhost_get_used_size(vq, vq->num))); } /* Can we start vq? */ /* Caller should have vq mutex and device mutex */ bool vhost_vq_access_ok(struct vhost_virtqueue *vq) { if (!vq_log_access_ok(vq, vq->log_base)) return false; /* Access validation occurs at prefetch time with IOTLB */ if (vq->iotlb) return true; return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used); } EXPORT_SYMBOL_GPL(vhost_vq_access_ok); static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m) { struct vhost_memory mem, *newmem; struct vhost_memory_region *region; struct vhost_iotlb *newumem, *oldumem; unsigned long size = offsetof(struct vhost_memory, regions); int i; if (copy_from_user(&mem, m, size)) return -EFAULT; if (mem.padding) return -EOPNOTSUPP; if (mem.nregions > max_mem_regions) return -E2BIG; newmem = kvzalloc(struct_size(newmem, regions, mem.nregions), GFP_KERNEL); if (!newmem) return -ENOMEM; memcpy(newmem, &mem, size); if (copy_from_user(newmem->regions, m->regions, mem.nregions * sizeof *m->regions)) { kvfree(newmem); return -EFAULT; } newumem = iotlb_alloc(); if (!newumem) { kvfree(newmem); return -ENOMEM; } for (region = newmem->regions; region < newmem->regions + mem.nregions; region++) { if (vhost_iotlb_add_range(newumem, region->guest_phys_addr, region->guest_phys_addr + region->memory_size - 1, region->userspace_addr, VHOST_MAP_RW)) goto err; } if (!memory_access_ok(d, newumem, 0)) goto err; oldumem = d->umem; d->umem = newumem; /* All memory accesses are done under some VQ mutex. */ for (i = 0; i < d->nvqs; ++i) { mutex_lock(&d->vqs[i]->mutex); d->vqs[i]->umem = newumem; mutex_unlock(&d->vqs[i]->mutex); } kvfree(newmem); vhost_iotlb_free(oldumem); return 0; err: vhost_iotlb_free(newumem); kvfree(newmem); return -EFAULT; } static long vhost_vring_set_num(struct vhost_dev *d, struct vhost_virtqueue *vq, void __user *argp) { struct vhost_vring_state s; /* Resizing ring with an active backend? * You don't want to do that. */ if (vq->private_data) return -EBUSY; if (copy_from_user(&s, argp, sizeof s)) return -EFAULT; if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) return -EINVAL; vq->num = s.num; return 0; } static long vhost_vring_set_addr(struct vhost_dev *d, struct vhost_virtqueue *vq, void __user *argp) { struct vhost_vring_addr a; if (copy_from_user(&a, argp, sizeof a)) return -EFAULT; if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) return -EOPNOTSUPP; /* For 32bit, verify that the top 32bits of the user data are set to zero. */ if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr || (u64)(unsigned long)a.used_user_addr != a.used_user_addr || (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) return -EFAULT; /* Make sure it's safe to cast pointers to vring types. */ BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE); BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE); if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) || (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) || (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) return -EINVAL; /* We only verify access here if backend is configured. * If it is not, we don't as size might not have been setup. * We will verify when backend is configured. */ if (vq->private_data) { if (!vq_access_ok(vq, vq->num, (void __user *)(unsigned long)a.desc_user_addr, (void __user *)(unsigned long)a.avail_user_addr, (void __user *)(unsigned long)a.used_user_addr)) return -EINVAL; /* Also validate log access for used ring if enabled. */ if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) && !log_access_ok(vq->log_base, a.log_guest_addr, sizeof *vq->used + vq->num * sizeof *vq->used->ring)) return -EINVAL; } vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG)); vq->desc = (void __user *)(unsigned long)a.desc_user_addr; vq->avail = (void __user *)(unsigned long)a.avail_user_addr; vq->log_addr = a.log_guest_addr; vq->used = (void __user *)(unsigned long)a.used_user_addr; return 0; } static long vhost_vring_set_num_addr(struct vhost_dev *d, struct vhost_virtqueue *vq, unsigned int ioctl, void __user *argp) { long r; mutex_lock(&vq->mutex); switch (ioctl) { case VHOST_SET_VRING_NUM: r = vhost_vring_set_num(d, vq, argp); break; case VHOST_SET_VRING_ADDR: r = vhost_vring_set_addr(d, vq, argp); break; default: BUG(); } mutex_unlock(&vq->mutex); return r; } long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp) { struct file *eventfp, *filep = NULL; bool pollstart = false, pollstop = false; struct eventfd_ctx *ctx = NULL; u32 __user *idxp = argp; struct vhost_virtqueue *vq; struct vhost_vring_state s; struct vhost_vring_file f; u32 idx; long r; r = get_user(idx, idxp); if (r < 0) return r; if (idx >= d->nvqs) return -ENOBUFS; idx = array_index_nospec(idx, d->nvqs); vq = d->vqs[idx]; if (ioctl == VHOST_SET_VRING_NUM || ioctl == VHOST_SET_VRING_ADDR) { return vhost_vring_set_num_addr(d, vq, ioctl, argp); } mutex_lock(&vq->mutex); switch (ioctl) { case VHOST_SET_VRING_BASE: /* Moving base with an active backend? * You don't want to do that. */ if (vq->private_data) { r = -EBUSY; break; } if (copy_from_user(&s, argp, sizeof s)) { r = -EFAULT; break; } if (s.num > 0xffff) { r = -EINVAL; break; } vq->last_avail_idx = s.num; /* Forget the cached index value. */ vq->avail_idx = vq->last_avail_idx; break; case VHOST_GET_VRING_BASE: s.index = idx; s.num = vq->last_avail_idx; if (copy_to_user(argp, &s, sizeof s)) r = -EFAULT; break; case VHOST_SET_VRING_KICK: if (copy_from_user(&f, argp, sizeof f)) { r = -EFAULT; break; } eventfp = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_fget(f.fd); if (IS_ERR(eventfp)) { r = PTR_ERR(eventfp); break; } if (eventfp != vq->kick) { pollstop = (filep = vq->kick) != NULL; pollstart = (vq->kick = eventfp) != NULL; } else filep = eventfp; break; case VHOST_SET_VRING_CALL: if (copy_from_user(&f, argp, sizeof f)) { r = -EFAULT; break; } ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd); if (IS_ERR(ctx)) { r = PTR_ERR(ctx); break; } swap(ctx, vq->call_ctx); break; case VHOST_SET_VRING_ERR: if (copy_from_user(&f, argp, sizeof f)) { r = -EFAULT; break; } ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd); if (IS_ERR(ctx)) { r = PTR_ERR(ctx); break; } swap(ctx, vq->error_ctx); break; case VHOST_SET_VRING_ENDIAN: r = vhost_set_vring_endian(vq, argp); break; case VHOST_GET_VRING_ENDIAN: r = vhost_get_vring_endian(vq, idx, argp); break; case VHOST_SET_VRING_BUSYLOOP_TIMEOUT: if (copy_from_user(&s, argp, sizeof(s))) { r = -EFAULT; break; } vq->busyloop_timeout = s.num; break; case VHOST_GET_VRING_BUSYLOOP_TIMEOUT: s.index = idx; s.num = vq->busyloop_timeout; if (copy_to_user(argp, &s, sizeof(s))) r = -EFAULT; break; default: r = -ENOIOCTLCMD; } if (pollstop && vq->handle_kick) vhost_poll_stop(&vq->poll); if (!IS_ERR_OR_NULL(ctx)) eventfd_ctx_put(ctx); if (filep) fput(filep); if (pollstart && vq->handle_kick) r = vhost_poll_start(&vq->poll, vq->kick); mutex_unlock(&vq->mutex); if (pollstop && vq->handle_kick) vhost_poll_flush(&vq->poll); return r; } EXPORT_SYMBOL_GPL(vhost_vring_ioctl); int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled) { struct vhost_iotlb *niotlb, *oiotlb; int i; niotlb = iotlb_alloc(); if (!niotlb) return -ENOMEM; oiotlb = d->iotlb; d->iotlb = niotlb; for (i = 0; i < d->nvqs; ++i) { struct vhost_virtqueue *vq = d->vqs[i]; mutex_lock(&vq->mutex); vq->iotlb = niotlb; __vhost_vq_meta_reset(vq); mutex_unlock(&vq->mutex); } vhost_iotlb_free(oiotlb); return 0; } EXPORT_SYMBOL_GPL(vhost_init_device_iotlb); /* Caller must have device mutex */ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp) { struct eventfd_ctx *ctx; u64 p; long r; int i, fd; /* If you are not the owner, you can become one */ if (ioctl == VHOST_SET_OWNER) { r = vhost_dev_set_owner(d); goto done; } /* You must be the owner to do anything else */ r = vhost_dev_check_owner(d); if (r) goto done; switch (ioctl) { case VHOST_SET_MEM_TABLE: r = vhost_set_memory(d, argp); break; case VHOST_SET_LOG_BASE: if (copy_from_user(&p, argp, sizeof p)) { r = -EFAULT; break; } if ((u64)(unsigned long)p != p) { r = -EFAULT; break; } for (i = 0; i < d->nvqs; ++i) { struct vhost_virtqueue *vq; void __user *base = (void __user *)(unsigned long)p; vq = d->vqs[i]; mutex_lock(&vq->mutex); /* If ring is inactive, will check when it's enabled. */ if (vq->private_data && !vq_log_access_ok(vq, base)) r = -EFAULT; else vq->log_base = base; mutex_unlock(&vq->mutex); } break; case VHOST_SET_LOG_FD: r = get_user(fd, (int __user *)argp); if (r < 0) break; ctx = fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(fd); if (IS_ERR(ctx)) { r = PTR_ERR(ctx); break; } swap(ctx, d->log_ctx); for (i = 0; i < d->nvqs; ++i) { mutex_lock(&d->vqs[i]->mutex); d->vqs[i]->log_ctx = d->log_ctx; mutex_unlock(&d->vqs[i]->mutex); } if (ctx) eventfd_ctx_put(ctx); break; default: r = -ENOIOCTLCMD; break; } done: return r; } EXPORT_SYMBOL_GPL(vhost_dev_ioctl); /* TODO: This is really inefficient. We need something like get_user() * (instruction directly accesses the data, with an exception table entry * returning -EFAULT). See Documentation/x86/exception-tables.rst. */ static int set_bit_to_user(int nr, void __user *addr) { unsigned long log = (unsigned long)addr; struct page *page; void *base; int bit = nr + (log % PAGE_SIZE) * 8; int r; r = pin_user_pages_fast(log, 1, FOLL_WRITE, &page); if (r < 0) return r; BUG_ON(r != 1); base = kmap_atomic(page); set_bit(bit, base); kunmap_atomic(base); unpin_user_pages_dirty_lock(&page, 1, true); return 0; } static int log_write(void __user *log_base, u64 write_address, u64 write_length) { u64 write_page = write_address / VHOST_PAGE_SIZE; int r; if (!write_length) return 0; write_length += write_address % VHOST_PAGE_SIZE; for (;;) { u64 base = (u64)(unsigned long)log_base; u64 log = base + write_page / 8; int bit = write_page % 8; if ((u64)(unsigned long)log != log) return -EFAULT; r = set_bit_to_user(bit, (void __user *)(unsigned long)log); if (r < 0) return r; if (write_length <= VHOST_PAGE_SIZE) break; write_length -= VHOST_PAGE_SIZE; write_page += 1; } return r; } static int log_write_hva(struct vhost_virtqueue *vq, u64 hva, u64 len) { struct vhost_iotlb *umem = vq->umem; struct vhost_iotlb_map *u; u64 start, end, l, min; int r; bool hit = false; while (len) { min = len; /* More than one GPAs can be mapped into a single HVA. So * iterate all possible umems here to be safe. */ list_for_each_entry(u, &umem->list, link) { if (u->addr > hva - 1 + len || u->addr - 1 + u->size < hva) continue; start = max(u->addr, hva); end = min(u->addr - 1 + u->size, hva - 1 + len); l = end - start + 1; r = log_write(vq->log_base, u->start + start - u->addr, l); if (r < 0) return r; hit = true; min = min(l, min); } if (!hit) return -EFAULT; len -= min; hva += min; } return 0; } static int log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len) { struct iovec iov[64]; int i, ret; if (!vq->iotlb) return log_write(vq->log_base, vq->log_addr + used_offset, len); ret = translate_desc(vq, (uintptr_t)vq->used + used_offset, len, iov, 64, VHOST_ACCESS_WO); if (ret < 0) return ret; for (i = 0; i < ret; i++) { ret = log_write_hva(vq, (uintptr_t)iov[i].iov_base, iov[i].iov_len); if (ret) return ret; } return 0; } int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, unsigned int log_num, u64 len, struct iovec *iov, int count) { int i, r; /* Make sure data written is seen before log. */ smp_wmb(); if (vq->iotlb) { for (i = 0; i < count; i++) { r = log_write_hva(vq, (uintptr_t)iov[i].iov_base, iov[i].iov_len); if (r < 0) return r; } return 0; } for (i = 0; i < log_num; ++i) { u64 l = min(log[i].len, len); r = log_write(vq->log_base, log[i].addr, l); if (r < 0) return r; len -= l; if (!len) { if (vq->log_ctx) eventfd_signal(vq->log_ctx, 1); return 0; } } /* Length written exceeds what we have stored. This is a bug. */ BUG(); return 0; } EXPORT_SYMBOL_GPL(vhost_log_write); static int vhost_update_used_flags(struct vhost_virtqueue *vq) { void __user *used; if (vhost_put_used_flags(vq)) return -EFAULT; if (unlikely(vq->log_used)) { /* Make sure the flag is seen before log. */ smp_wmb(); /* Log used flag write. */ used = &vq->used->flags; log_used(vq, (used - (void __user *)vq->used), sizeof vq->used->flags); if (vq->log_ctx) eventfd_signal(vq->log_ctx, 1); } return 0; } static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event) { if (vhost_put_avail_event(vq)) return -EFAULT; if (unlikely(vq->log_used)) { void __user *used; /* Make sure the event is seen before log. */ smp_wmb(); /* Log avail event write */ used = vhost_avail_event(vq); log_used(vq, (used - (void __user *)vq->used), sizeof *vhost_avail_event(vq)); if (vq->log_ctx) eventfd_signal(vq->log_ctx, 1); } return 0; } int vhost_vq_init_access(struct vhost_virtqueue *vq) { __virtio16 last_used_idx; int r; bool is_le = vq->is_le; if (!vq->private_data) return 0; vhost_init_is_le(vq); r = vhost_update_used_flags(vq); if (r) goto err; vq->signalled_used_valid = false; if (!vq->iotlb && !access_ok(&vq->used->idx, sizeof vq->used->idx)) { r = -EFAULT; goto err; } r = vhost_get_used_idx(vq, &last_used_idx); if (r) { vq_err(vq, "Can't access used idx at %p\n", &vq->used->idx); goto err; } vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx); return 0; err: vq->is_le = is_le; return r; } EXPORT_SYMBOL_GPL(vhost_vq_init_access); static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len, struct iovec iov[], int iov_size, int access) { const struct vhost_iotlb_map *map; struct vhost_dev *dev = vq->dev; struct vhost_iotlb *umem = dev->iotlb ? dev->iotlb : dev->umem; struct iovec *_iov; u64 s = 0; int ret = 0; while ((u64)len > s) { u64 size; if (unlikely(ret >= iov_size)) { ret = -ENOBUFS; break; } map = vhost_iotlb_itree_first(umem, addr, addr + len - 1); if (map == NULL || map->start > addr) { if (umem != dev->iotlb) { ret = -EFAULT; break; } ret = -EAGAIN; break; } else if (!(map->perm & access)) { ret = -EPERM; break; } _iov = iov + ret; size = map->size - addr + map->start; _iov->iov_len = min((u64)len - s, size); _iov->iov_base = (void __user *)(unsigned long) (map->addr + addr - map->start); s += size; addr += size; ++ret; } if (ret == -EAGAIN) vhost_iotlb_miss(vq, addr, access); return ret; } /* Each buffer in the virtqueues is actually a chain of descriptors. This * function returns the next descriptor in the chain, * or -1U if we're at the end. */ static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc) { unsigned int next; /* If this descriptor says it doesn't chain, we're done. */ if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT))) return -1U; /* Check they're not leading us off end of descriptors. */ next = vhost16_to_cpu(vq, READ_ONCE(desc->next)); return next; } static int get_indirect(struct vhost_virtqueue *vq, struct iovec iov[], unsigned int iov_size, unsigned int *out_num, unsigned int *in_num, struct vhost_log *log, unsigned int *log_num, struct vring_desc *indirect) { struct vring_desc desc; unsigned int i = 0, count, found = 0; u32 len = vhost32_to_cpu(vq, indirect->len); struct iov_iter from; int ret, access; /* Sanity check */ if (unlikely(len % sizeof desc)) { vq_err(vq, "Invalid length in indirect descriptor: " "len 0x%llx not multiple of 0x%zx\n", (unsigned long long)len, sizeof desc); return -EINVAL; } ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect, UIO_MAXIOV, VHOST_ACCESS_RO); if (unlikely(ret < 0)) { if (ret != -EAGAIN) vq_err(vq, "Translation failure %d in indirect.\n", ret); return ret; } iov_iter_init(&from, READ, vq->indirect, ret, len); /* We will use the result as an address to read from, so most * architectures only need a compiler barrier here. */ read_barrier_depends(); count = len / sizeof desc; /* Buffers are chained via a 16 bit next field, so * we can have at most 2^16 of these. */ if (unlikely(count > USHRT_MAX + 1)) { vq_err(vq, "Indirect buffer length too big: %d\n", indirect->len); return -E2BIG; } do { unsigned iov_count = *in_num + *out_num; if (unlikely(++found > count)) { vq_err(vq, "Loop detected: last one at %u " "indirect size %u\n", i, count); return -EINVAL; } if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) { vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc); return -EINVAL; } if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) { vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc); return -EINVAL; } if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) access = VHOST_ACCESS_WO; else access = VHOST_ACCESS_RO; ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr), vhost32_to_cpu(vq, desc.len), iov + iov_count, iov_size - iov_count, access); if (unlikely(ret < 0)) { if (ret != -EAGAIN) vq_err(vq, "Translation failure %d indirect idx %d\n", ret, i); return ret; } /* If this is an input descriptor, increment that count. */ if (access == VHOST_ACCESS_WO) { *in_num += ret; if (unlikely(log && ret)) { log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); log[*log_num].len = vhost32_to_cpu(vq, desc.len); ++*log_num; } } else { /* If it's an output descriptor, they're all supposed * to come before any input descriptors. */ if (unlikely(*in_num)) { vq_err(vq, "Indirect descriptor " "has out after in: idx %d\n", i); return -EINVAL; } *out_num += ret; } } while ((i = next_desc(vq, &desc)) != -1); return 0; } /* This looks in the virtqueue and for the first available buffer, and converts * it to an iovec for convenient access. Since descriptors consist of some * number of output then some number of input descriptors, it's actually two * iovecs, but we pack them into one and note how many of each there were. * * This function returns the descriptor number found, or vq->num (which is * never a valid descriptor number) if none was found. A negative code is * returned on error. */ int vhost_get_vq_desc(struct vhost_virtqueue *vq, struct iovec iov[], unsigned int iov_size, unsigned int *out_num, unsigned int *in_num, struct vhost_log *log, unsigned int *log_num) { struct vring_desc desc; unsigned int i, head, found = 0; u16 last_avail_idx; __virtio16 avail_idx; __virtio16 ring_head; int ret, access; /* Check it isn't doing very strange things with descriptor numbers. */ last_avail_idx = vq->last_avail_idx; if (vq->avail_idx == vq->last_avail_idx) { if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) { vq_err(vq, "Failed to access avail idx at %p\n", &vq->avail->idx); return -EFAULT; } vq->avail_idx = vhost16_to_cpu(vq, avail_idx); if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) { vq_err(vq, "Guest moved used index from %u to %u", last_avail_idx, vq->avail_idx); return -EFAULT; } /* If there's nothing new since last we looked, return * invalid. */ if (vq->avail_idx == last_avail_idx) return vq->num; /* Only get avail ring entries after they have been * exposed by guest. */ smp_rmb(); } /* Grab the next descriptor number they're advertising, and increment * the index we've seen. */ if (unlikely(vhost_get_avail_head(vq, &ring_head, last_avail_idx))) { vq_err(vq, "Failed to read head: idx %d address %p\n", last_avail_idx, &vq->avail->ring[last_avail_idx % vq->num]); return -EFAULT; } head = vhost16_to_cpu(vq, ring_head); /* If their number is silly, that's an error. */ if (unlikely(head >= vq->num)) { vq_err(vq, "Guest says index %u > %u is available", head, vq->num); return -EINVAL; } /* When we start there are none of either input nor output. */ *out_num = *in_num = 0; if (unlikely(log)) *log_num = 0; i = head; do { unsigned iov_count = *in_num + *out_num; if (unlikely(i >= vq->num)) { vq_err(vq, "Desc index is %u > %u, head = %u", i, vq->num, head); return -EINVAL; } if (unlikely(++found > vq->num)) { vq_err(vq, "Loop detected: last one at %u " "vq size %u head %u\n", i, vq->num, head); return -EINVAL; } ret = vhost_get_desc(vq, &desc, i); if (unlikely(ret)) { vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", i, vq->desc + i); return -EFAULT; } if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) { ret = get_indirect(vq, iov, iov_size, out_num, in_num, log, log_num, &desc); if (unlikely(ret < 0)) { if (ret != -EAGAIN) vq_err(vq, "Failure detected " "in indirect descriptor at idx %d\n", i); return ret; } continue; } if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) access = VHOST_ACCESS_WO; else access = VHOST_ACCESS_RO; ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr), vhost32_to_cpu(vq, desc.len), iov + iov_count, iov_size - iov_count, access); if (unlikely(ret < 0)) { if (ret != -EAGAIN) vq_err(vq, "Translation failure %d descriptor idx %d\n", ret, i); return ret; } if (access == VHOST_ACCESS_WO) { /* If this is an input descriptor, * increment that count. */ *in_num += ret; if (unlikely(log && ret)) { log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); log[*log_num].len = vhost32_to_cpu(vq, desc.len); ++*log_num; } } else { /* If it's an output descriptor, they're all supposed * to come before any input descriptors. */ if (unlikely(*in_num)) { vq_err(vq, "Descriptor has out after in: " "idx %d\n", i); return -EINVAL; } *out_num += ret; } } while ((i = next_desc(vq, &desc)) != -1); /* On success, increment avail index. */ vq->last_avail_idx++; /* Assume notifications from guest are disabled at this point, * if they aren't we would need to update avail_event index. */ BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY)); return head; } EXPORT_SYMBOL_GPL(vhost_get_vq_desc); /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n) { vq->last_avail_idx -= n; } EXPORT_SYMBOL_GPL(vhost_discard_vq_desc); /* After we've used one of their buffers, we tell them about it. We'll then * want to notify the guest, using eventfd. */ int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len) { struct vring_used_elem heads = { cpu_to_vhost32(vq, head), cpu_to_vhost32(vq, len) }; return vhost_add_used_n(vq, &heads, 1); } EXPORT_SYMBOL_GPL(vhost_add_used); static int __vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads, unsigned count) { vring_used_elem_t __user *used; u16 old, new; int start; start = vq->last_used_idx & (vq->num - 1); used = vq->used->ring + start; if (vhost_put_used(vq, heads, start, count)) { vq_err(vq, "Failed to write used"); return -EFAULT; } if (unlikely(vq->log_used)) { /* Make sure data is seen before log. */ smp_wmb(); /* Log used ring entry write. */ log_used(vq, ((void __user *)used - (void __user *)vq->used), count * sizeof *used); } old = vq->last_used_idx; new = (vq->last_used_idx += count); /* If the driver never bothers to signal in a very long while, * used index might wrap around. If that happens, invalidate * signalled_used index we stored. TODO: make sure driver * signals at least once in 2^16 and remove this. */ if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old))) vq->signalled_used_valid = false; return 0; } /* After we've used one of their buffers, we tell them about it. We'll then * want to notify the guest, using eventfd. */ int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads, unsigned count) { int start, n, r; start = vq->last_used_idx & (vq->num - 1); n = vq->num - start; if (n < count) { r = __vhost_add_used_n(vq, heads, n); if (r < 0) return r; heads += n; count -= n; } r = __vhost_add_used_n(vq, heads, count); /* Make sure buffer is written before we update index. */ smp_wmb(); if (vhost_put_used_idx(vq)) { vq_err(vq, "Failed to increment used idx"); return -EFAULT; } if (unlikely(vq->log_used)) { /* Make sure used idx is seen before log. */ smp_wmb(); /* Log used index update. */ log_used(vq, offsetof(struct vring_used, idx), sizeof vq->used->idx); if (vq->log_ctx) eventfd_signal(vq->log_ctx, 1); } return r; } EXPORT_SYMBOL_GPL(vhost_add_used_n); static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) { __u16 old, new; __virtio16 event; bool v; /* Flush out used index updates. This is paired * with the barrier that the Guest executes when enabling * interrupts. */ smp_mb(); if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) && unlikely(vq->avail_idx == vq->last_avail_idx)) return true; if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { __virtio16 flags; if (vhost_get_avail_flags(vq, &flags)) { vq_err(vq, "Failed to get flags"); return true; } return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT)); } old = vq->signalled_used; v = vq->signalled_used_valid; new = vq->signalled_used = vq->last_used_idx; vq->signalled_used_valid = true; if (unlikely(!v)) return true; if (vhost_get_used_event(vq, &event)) { vq_err(vq, "Failed to get used event idx"); return true; } return vring_need_event(vhost16_to_cpu(vq, event), new, old); } /* This actually signals the guest, using eventfd. */ void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) { /* Signal the Guest tell them we used something up. */ if (vq->call_ctx && vhost_notify(dev, vq)) eventfd_signal(vq->call_ctx, 1); } EXPORT_SYMBOL_GPL(vhost_signal); /* And here's the combo meal deal. Supersize me! */ void vhost_add_used_and_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq, unsigned int head, int len) { vhost_add_used(vq, head, len); vhost_signal(dev, vq); } EXPORT_SYMBOL_GPL(vhost_add_used_and_signal); /* multi-buffer version of vhost_add_used_and_signal */ void vhost_add_used_and_signal_n(struct vhost_dev *dev, struct vhost_virtqueue *vq, struct vring_used_elem *heads, unsigned count) { vhost_add_used_n(vq, heads, count); vhost_signal(dev, vq); } EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n); /* return true if we're sure that avaiable ring is empty */ bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq) { __virtio16 avail_idx; int r; if (vq->avail_idx != vq->last_avail_idx) return false; r = vhost_get_avail_idx(vq, &avail_idx); if (unlikely(r)) return false; vq->avail_idx = vhost16_to_cpu(vq, avail_idx); return vq->avail_idx == vq->last_avail_idx; } EXPORT_SYMBOL_GPL(vhost_vq_avail_empty); /* OK, now we need to know about added descriptors. */ bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) { __virtio16 avail_idx; int r; if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) return false; vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { r = vhost_update_used_flags(vq); if (r) { vq_err(vq, "Failed to enable notification at %p: %d\n", &vq->used->flags, r); return false; } } else { r = vhost_update_avail_event(vq, vq->avail_idx); if (r) { vq_err(vq, "Failed to update avail event index at %p: %d\n", vhost_avail_event(vq), r); return false; } } /* They could have slipped one in as we were doing that: make * sure it's written, then check again. */ smp_mb(); r = vhost_get_avail_idx(vq, &avail_idx); if (r) { vq_err(vq, "Failed to check avail idx at %p: %d\n", &vq->avail->idx, r); return false; } return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx; } EXPORT_SYMBOL_GPL(vhost_enable_notify); /* We don't need to be notified again. */ void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) { int r; if (vq->used_flags & VRING_USED_F_NO_NOTIFY) return; vq->used_flags |= VRING_USED_F_NO_NOTIFY; if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { r = vhost_update_used_flags(vq); if (r) vq_err(vq, "Failed to enable notification at %p: %d\n", &vq->used->flags, r); } } EXPORT_SYMBOL_GPL(vhost_disable_notify); /* Create a new message. */ struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type) { struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL); if (!node) return NULL; /* Make sure all padding within the structure is initialized. */ memset(&node->msg, 0, sizeof node->msg); node->vq = vq; node->msg.type = type; return node; } EXPORT_SYMBOL_GPL(vhost_new_msg); void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head, struct vhost_msg_node *node) { spin_lock(&dev->iotlb_lock); list_add_tail(&node->node, head); spin_unlock(&dev->iotlb_lock); wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM); } EXPORT_SYMBOL_GPL(vhost_enqueue_msg); struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev, struct list_head *head) { struct vhost_msg_node *node = NULL; spin_lock(&dev->iotlb_lock); if (!list_empty(head)) { node = list_first_entry(head, struct vhost_msg_node, node); list_del(&node->node); } spin_unlock(&dev->iotlb_lock); return node; } EXPORT_SYMBOL_GPL(vhost_dequeue_msg); static int __init vhost_init(void) { return 0; } static void __exit vhost_exit(void) { } module_init(vhost_init); module_exit(vhost_exit); MODULE_VERSION("0.0.1"); MODULE_LICENSE("GPL v2"); MODULE_AUTHOR("Michael S. Tsirkin"); MODULE_DESCRIPTION("Host kernel accelerator for virtio");
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