| /* 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 |
| * |
| * This work is licensed under the terms of the GNU GPL, version 2. |
| * |
| * 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/mmu_context.h> |
| #include <linux/miscdevice.h> |
| #include <linux/mutex.h> |
| #include <linux/rcupdate.h> |
| #include <linux/poll.h> |
| #include <linux/file.h> |
| #include <linux/highmem.h> |
| #include <linux/slab.h> |
| #include <linux/kthread.h> |
| #include <linux/cgroup.h> |
| #include <linux/module.h> |
| |
| #include "vhost.h" |
| |
| enum { |
| VHOST_MEMORY_MAX_NREGIONS = 64, |
| VHOST_MEMORY_F_LOG = 0x1, |
| }; |
| |
| #define vhost_used_event(vq) ((u16 __user *)&vq->avail->ring[vq->num]) |
| #define vhost_avail_event(vq) ((u16 __user *)&vq->used->ring[vq->num]) |
| |
| 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_t *wait, unsigned mode, int sync, |
| void *key) |
| { |
| struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait); |
| |
| if (!((unsigned long)key & poll->mask)) |
| return 0; |
| |
| vhost_poll_queue(poll); |
| return 0; |
| } |
| |
| void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn) |
| { |
| INIT_LIST_HEAD(&work->node); |
| work->fn = fn; |
| init_waitqueue_head(&work->done); |
| work->flushing = 0; |
| work->queue_seq = work->done_seq = 0; |
| } |
| EXPORT_SYMBOL_GPL(vhost_work_init); |
| |
| /* Init poll structure */ |
| void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, |
| unsigned long 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) |
| { |
| unsigned long mask; |
| int ret = 0; |
| |
| if (poll->wqh) |
| return 0; |
| |
| mask = file->f_op->poll(file, &poll->table); |
| if (mask) |
| vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask); |
| if (mask & POLLERR) { |
| if (poll->wqh) |
| remove_wait_queue(poll->wqh, &poll->wait); |
| ret = -EINVAL; |
| } |
| |
| return ret; |
| } |
| 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); |
| |
| static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work, |
| unsigned seq) |
| { |
| int left; |
| |
| spin_lock_irq(&dev->work_lock); |
| left = seq - work->done_seq; |
| spin_unlock_irq(&dev->work_lock); |
| return left <= 0; |
| } |
| |
| void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work) |
| { |
| unsigned seq; |
| int flushing; |
| |
| spin_lock_irq(&dev->work_lock); |
| seq = work->queue_seq; |
| work->flushing++; |
| spin_unlock_irq(&dev->work_lock); |
| wait_event(work->done, vhost_work_seq_done(dev, work, seq)); |
| spin_lock_irq(&dev->work_lock); |
| flushing = --work->flushing; |
| spin_unlock_irq(&dev->work_lock); |
| BUG_ON(flushing < 0); |
| } |
| 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) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(&dev->work_lock, flags); |
| if (list_empty(&work->node)) { |
| list_add_tail(&work->node, &dev->work_list); |
| work->queue_seq++; |
| wake_up_process(dev->worker); |
| } |
| spin_unlock_irqrestore(&dev->work_lock, flags); |
| } |
| EXPORT_SYMBOL_GPL(vhost_work_queue); |
| |
| 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_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->log_base = NULL; |
| vq->error_ctx = NULL; |
| vq->error = NULL; |
| vq->kick = NULL; |
| vq->call_ctx = NULL; |
| vq->call = NULL; |
| vq->log_ctx = NULL; |
| } |
| |
| static int vhost_worker(void *data) |
| { |
| struct vhost_dev *dev = data; |
| struct vhost_work *work = NULL; |
| unsigned uninitialized_var(seq); |
| mm_segment_t oldfs = get_fs(); |
| |
| set_fs(USER_DS); |
| use_mm(dev->mm); |
| |
| for (;;) { |
| /* mb paired w/ kthread_stop */ |
| set_current_state(TASK_INTERRUPTIBLE); |
| |
| spin_lock_irq(&dev->work_lock); |
| if (work) { |
| work->done_seq = seq; |
| if (work->flushing) |
| wake_up_all(&work->done); |
| } |
| |
| if (kthread_should_stop()) { |
| spin_unlock_irq(&dev->work_lock); |
| __set_current_state(TASK_RUNNING); |
| break; |
| } |
| if (!list_empty(&dev->work_list)) { |
| work = list_first_entry(&dev->work_list, |
| struct vhost_work, node); |
| list_del_init(&work->node); |
| seq = work->queue_seq; |
| } else |
| work = NULL; |
| spin_unlock_irq(&dev->work_lock); |
| |
| if (work) { |
| __set_current_state(TASK_RUNNING); |
| work->fn(work); |
| if (need_resched()) |
| schedule(); |
| } else |
| schedule(); |
| |
| } |
| unuse_mm(dev->mm); |
| set_fs(oldfs); |
| 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(sizeof *vq->indirect * UIO_MAXIOV, |
| GFP_KERNEL); |
| vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL); |
| vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, 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]); |
| } |
| |
| long vhost_dev_init(struct vhost_dev *dev, |
| struct vhost_virtqueue **vqs, int nvqs) |
| { |
| struct vhost_virtqueue *vq; |
| int i; |
| |
| dev->vqs = vqs; |
| dev->nvqs = nvqs; |
| mutex_init(&dev->mutex); |
| dev->log_ctx = NULL; |
| dev->log_file = NULL; |
| dev->memory = NULL; |
| dev->mm = NULL; |
| spin_lock_init(&dev->work_lock); |
| INIT_LIST_HEAD(&dev->work_list); |
| dev->worker = NULL; |
| |
| 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, |
| POLLIN, dev); |
| } |
| |
| return 0; |
| } |
| 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); |
| |
| /* 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; |
| } |
| |
| /* No owner, become one */ |
| dev->mm = get_task_mm(current); |
| 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: |
| kthread_stop(worker); |
| dev->worker = NULL; |
| err_worker: |
| if (dev->mm) |
| mmput(dev->mm); |
| dev->mm = NULL; |
| err_mm: |
| return err; |
| } |
| EXPORT_SYMBOL_GPL(vhost_dev_set_owner); |
| |
| struct vhost_memory *vhost_dev_reset_owner_prepare(void) |
| { |
| return kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL); |
| } |
| EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare); |
| |
| /* Caller should have device mutex */ |
| void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_memory *memory) |
| { |
| vhost_dev_cleanup(dev, true); |
| |
| /* Restore memory to default empty mapping. */ |
| memory->nregions = 0; |
| RCU_INIT_POINTER(dev->memory, memory); |
| } |
| 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); |
| |
| /* Caller should have device mutex if and only if locked is set */ |
| void vhost_dev_cleanup(struct vhost_dev *dev, bool locked) |
| { |
| 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]->error) |
| fput(dev->vqs[i]->error); |
| if (dev->vqs[i]->kick) |
| fput(dev->vqs[i]->kick); |
| if (dev->vqs[i]->call_ctx) |
| eventfd_ctx_put(dev->vqs[i]->call_ctx); |
| if (dev->vqs[i]->call) |
| fput(dev->vqs[i]->call); |
| 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; |
| if (dev->log_file) |
| fput(dev->log_file); |
| dev->log_file = NULL; |
| /* No one will access memory at this point */ |
| kfree(rcu_dereference_protected(dev->memory, |
| locked == |
| lockdep_is_held(&dev->mutex))); |
| RCU_INIT_POINTER(dev->memory, NULL); |
| WARN_ON(!list_empty(&dev->work_list)); |
| if (dev->worker) { |
| kthread_stop(dev->worker); |
| dev->worker = NULL; |
| } |
| if (dev->mm) |
| mmput(dev->mm); |
| dev->mm = NULL; |
| } |
| EXPORT_SYMBOL_GPL(vhost_dev_cleanup); |
| |
| static int 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 0; |
| |
| return access_ok(VERIFY_WRITE, log_base + a, |
| (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8); |
| } |
| |
| /* Caller should have vq mutex and device mutex. */ |
| static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem, |
| int log_all) |
| { |
| int i; |
| |
| if (!mem) |
| return 0; |
| |
| for (i = 0; i < mem->nregions; ++i) { |
| struct vhost_memory_region *m = mem->regions + i; |
| unsigned long a = m->userspace_addr; |
| if (m->memory_size > ULONG_MAX) |
| return 0; |
| else if (!access_ok(VERIFY_WRITE, (void __user *)a, |
| m->memory_size)) |
| return 0; |
| else if (log_all && !log_access_ok(log_base, |
| m->guest_phys_addr, |
| m->memory_size)) |
| return 0; |
| } |
| return 1; |
| } |
| |
| /* Can we switch to this memory table? */ |
| /* Caller should have device mutex but not vq mutex */ |
| static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem, |
| int log_all) |
| { |
| int i; |
| |
| for (i = 0; i < d->nvqs; ++i) { |
| int ok; |
| mutex_lock(&d->vqs[i]->mutex); |
| /* 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, mem, |
| log_all); |
| else |
| ok = 1; |
| mutex_unlock(&d->vqs[i]->mutex); |
| if (!ok) |
| return 0; |
| } |
| return 1; |
| } |
| |
| static int vq_access_ok(struct vhost_dev *d, unsigned int num, |
| struct vring_desc __user *desc, |
| struct vring_avail __user *avail, |
| struct vring_used __user *used) |
| { |
| size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; |
| return access_ok(VERIFY_READ, desc, num * sizeof *desc) && |
| access_ok(VERIFY_READ, avail, |
| sizeof *avail + num * sizeof *avail->ring + s) && |
| access_ok(VERIFY_WRITE, used, |
| sizeof *used + num * sizeof *used->ring + s); |
| } |
| |
| /* Can we log writes? */ |
| /* Caller should have device mutex but not vq mutex */ |
| int vhost_log_access_ok(struct vhost_dev *dev) |
| { |
| struct vhost_memory *mp; |
| |
| mp = rcu_dereference_protected(dev->memory, |
| lockdep_is_held(&dev->mutex)); |
| return memory_access_ok(dev, mp, 1); |
| } |
| EXPORT_SYMBOL_GPL(vhost_log_access_ok); |
| |
| /* Verify access for write logging. */ |
| /* Caller should have vq mutex and device mutex */ |
| static int vq_log_access_ok(struct vhost_dev *d, struct vhost_virtqueue *vq, |
| void __user *log_base) |
| { |
| struct vhost_memory *mp; |
| size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; |
| |
| mp = rcu_dereference_protected(vq->dev->memory, |
| lockdep_is_held(&vq->mutex)); |
| return vq_memory_access_ok(log_base, mp, |
| vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) && |
| (!vq->log_used || log_access_ok(log_base, vq->log_addr, |
| sizeof *vq->used + |
| vq->num * sizeof *vq->used->ring + s)); |
| } |
| |
| /* Can we start vq? */ |
| /* Caller should have vq mutex and device mutex */ |
| int vhost_vq_access_ok(struct vhost_virtqueue *vq) |
| { |
| return vq_access_ok(vq->dev, vq->num, vq->desc, vq->avail, vq->used) && |
| vq_log_access_ok(vq->dev, vq, vq->log_base); |
| } |
| 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, *oldmem; |
| unsigned long size = offsetof(struct vhost_memory, regions); |
| |
| if (copy_from_user(&mem, m, size)) |
| return -EFAULT; |
| if (mem.padding) |
| return -EOPNOTSUPP; |
| if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS) |
| return -E2BIG; |
| newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL); |
| if (!newmem) |
| return -ENOMEM; |
| |
| memcpy(newmem, &mem, size); |
| if (copy_from_user(newmem->regions, m->regions, |
| mem.nregions * sizeof *m->regions)) { |
| kfree(newmem); |
| return -EFAULT; |
| } |
| |
| if (!memory_access_ok(d, newmem, |
| vhost_has_feature(d, VHOST_F_LOG_ALL))) { |
| kfree(newmem); |
| return -EFAULT; |
| } |
| oldmem = rcu_dereference_protected(d->memory, |
| lockdep_is_held(&d->mutex)); |
| rcu_assign_pointer(d->memory, newmem); |
| synchronize_rcu(); |
| kfree(oldmem); |
| return 0; |
| } |
| |
| long vhost_vring_ioctl(struct vhost_dev *d, 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; |
| struct vhost_vring_addr a; |
| u32 idx; |
| long r; |
| |
| r = get_user(idx, idxp); |
| if (r < 0) |
| return r; |
| if (idx >= d->nvqs) |
| return -ENOBUFS; |
| |
| vq = d->vqs[idx]; |
| |
| mutex_lock(&vq->mutex); |
| |
| switch (ioctl) { |
| case VHOST_SET_VRING_NUM: |
| /* Resizing ring 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 || s.num > 0xffff || (s.num & (s.num - 1))) { |
| r = -EINVAL; |
| break; |
| } |
| vq->num = s.num; |
| break; |
| 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_ADDR: |
| if (copy_from_user(&a, argp, sizeof a)) { |
| r = -EFAULT; |
| break; |
| } |
| if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) { |
| r = -EOPNOTSUPP; |
| break; |
| } |
| /* 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) { |
| r = -EFAULT; |
| break; |
| } |
| if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) || |
| (a.used_user_addr & (sizeof *vq->used->ring - 1)) || |
| (a.log_guest_addr & (sizeof *vq->used->ring - 1))) { |
| r = -EINVAL; |
| break; |
| } |
| |
| /* 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(d, 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)) { |
| r = -EINVAL; |
| break; |
| } |
| |
| /* 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)) { |
| r = -EINVAL; |
| break; |
| } |
| } |
| |
| 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; |
| break; |
| case VHOST_SET_VRING_KICK: |
| if (copy_from_user(&f, argp, sizeof f)) { |
| r = -EFAULT; |
| break; |
| } |
| eventfp = f.fd == -1 ? 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; |
| } |
| eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); |
| if (IS_ERR(eventfp)) { |
| r = PTR_ERR(eventfp); |
| break; |
| } |
| if (eventfp != vq->call) { |
| filep = vq->call; |
| ctx = vq->call_ctx; |
| vq->call = eventfp; |
| vq->call_ctx = eventfp ? |
| eventfd_ctx_fileget(eventfp) : NULL; |
| } else |
| filep = eventfp; |
| break; |
| case VHOST_SET_VRING_ERR: |
| if (copy_from_user(&f, argp, sizeof f)) { |
| r = -EFAULT; |
| break; |
| } |
| eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); |
| if (IS_ERR(eventfp)) { |
| r = PTR_ERR(eventfp); |
| break; |
| } |
| if (eventfp != vq->error) { |
| filep = vq->error; |
| vq->error = eventfp; |
| ctx = vq->error_ctx; |
| vq->error_ctx = eventfp ? |
| eventfd_ctx_fileget(eventfp) : NULL; |
| } else |
| filep = eventfp; |
| break; |
| default: |
| r = -ENOIOCTLCMD; |
| } |
| |
| if (pollstop && vq->handle_kick) |
| vhost_poll_stop(&vq->poll); |
| |
| if (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); |
| |
| /* Caller must have device mutex */ |
| long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp) |
| { |
| struct file *eventfp, *filep = NULL; |
| struct eventfd_ctx *ctx = NULL; |
| 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(d, 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; |
| eventfp = fd == -1 ? NULL : eventfd_fget(fd); |
| if (IS_ERR(eventfp)) { |
| r = PTR_ERR(eventfp); |
| break; |
| } |
| if (eventfp != d->log_file) { |
| filep = d->log_file; |
| ctx = d->log_ctx; |
| d->log_ctx = eventfp ? |
| eventfd_ctx_fileget(eventfp) : NULL; |
| } else |
| filep = eventfp; |
| 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); |
| if (filep) |
| fput(filep); |
| break; |
| default: |
| r = -ENOIOCTLCMD; |
| break; |
| } |
| done: |
| return r; |
| } |
| EXPORT_SYMBOL_GPL(vhost_dev_ioctl); |
| |
| static const struct vhost_memory_region *find_region(struct vhost_memory *mem, |
| __u64 addr, __u32 len) |
| { |
| struct vhost_memory_region *reg; |
| int i; |
| |
| /* linear search is not brilliant, but we really have on the order of 6 |
| * regions in practice */ |
| for (i = 0; i < mem->nregions; ++i) { |
| reg = mem->regions + i; |
| if (reg->guest_phys_addr <= addr && |
| reg->guest_phys_addr + reg->memory_size - 1 >= addr) |
| return reg; |
| } |
| return NULL; |
| } |
| |
| /* 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.txt. |
| */ |
| 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 = get_user_pages_fast(log, 1, 1, &page); |
| if (r < 0) |
| return r; |
| BUG_ON(r != 1); |
| base = kmap_atomic(page); |
| set_bit(bit, base); |
| kunmap_atomic(base); |
| set_page_dirty_lock(page); |
| put_page(page); |
| 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; |
| } |
| |
| int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, |
| unsigned int log_num, u64 len) |
| { |
| int i, r; |
| |
| /* Make sure data written is seen before log. */ |
| smp_wmb(); |
| 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 (__put_user(vq->used_flags, &vq->used->flags) < 0) |
| 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_write(vq->log_base, vq->log_addr + |
| (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 (__put_user(vq->avail_idx, vhost_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_write(vq->log_base, vq->log_addr + |
| (used - (void __user *)vq->used), |
| sizeof *vhost_avail_event(vq)); |
| if (vq->log_ctx) |
| eventfd_signal(vq->log_ctx, 1); |
| } |
| return 0; |
| } |
| |
| int vhost_init_used(struct vhost_virtqueue *vq) |
| { |
| int r; |
| if (!vq->private_data) |
| return 0; |
| |
| r = vhost_update_used_flags(vq); |
| if (r) |
| return r; |
| vq->signalled_used_valid = false; |
| return get_user(vq->last_used_idx, &vq->used->idx); |
| } |
| EXPORT_SYMBOL_GPL(vhost_init_used); |
| |
| static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len, |
| struct iovec iov[], int iov_size) |
| { |
| const struct vhost_memory_region *reg; |
| struct vhost_memory *mem; |
| struct iovec *_iov; |
| u64 s = 0; |
| int ret = 0; |
| |
| rcu_read_lock(); |
| |
| mem = rcu_dereference(dev->memory); |
| while ((u64)len > s) { |
| u64 size; |
| if (unlikely(ret >= iov_size)) { |
| ret = -ENOBUFS; |
| break; |
| } |
| reg = find_region(mem, addr, len); |
| if (unlikely(!reg)) { |
| ret = -EFAULT; |
| break; |
| } |
| _iov = iov + ret; |
| size = reg->memory_size - addr + reg->guest_phys_addr; |
| _iov->iov_len = min((u64)len - s, size); |
| _iov->iov_base = (void __user *)(unsigned long) |
| (reg->userspace_addr + addr - reg->guest_phys_addr); |
| s += size; |
| addr += size; |
| ++ret; |
| } |
| |
| rcu_read_unlock(); |
| 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 vring_desc *desc) |
| { |
| unsigned int next; |
| |
| /* If this descriptor says it doesn't chain, we're done. */ |
| if (!(desc->flags & VRING_DESC_F_NEXT)) |
| return -1U; |
| |
| /* Check they're not leading us off end of descriptors. */ |
| next = desc->next; |
| /* Make sure compiler knows to grab that: we don't want it changing! */ |
| /* We will use the result as an index in an array, so most |
| * architectures only need a compiler barrier here. */ |
| read_barrier_depends(); |
| |
| return next; |
| } |
| |
| static int get_indirect(struct vhost_dev *dev, 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; |
| int ret; |
| |
| /* Sanity check */ |
| if (unlikely(indirect->len % sizeof desc)) { |
| vq_err(vq, "Invalid length in indirect descriptor: " |
| "len 0x%llx not multiple of 0x%zx\n", |
| (unsigned long long)indirect->len, |
| sizeof desc); |
| return -EINVAL; |
| } |
| |
| ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect, |
| UIO_MAXIOV); |
| if (unlikely(ret < 0)) { |
| vq_err(vq, "Translation failure %d in indirect.\n", ret); |
| return ret; |
| } |
| |
| /* We will use the result as an address to read from, so most |
| * architectures only need a compiler barrier here. */ |
| read_barrier_depends(); |
| |
| count = indirect->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(memcpy_fromiovec((unsigned char *)&desc, |
| vq->indirect, sizeof desc))) { |
| vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", |
| i, (size_t)indirect->addr + i * sizeof desc); |
| return -EINVAL; |
| } |
| if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) { |
| vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", |
| i, (size_t)indirect->addr + i * sizeof desc); |
| return -EINVAL; |
| } |
| |
| ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, |
| iov_size - iov_count); |
| if (unlikely(ret < 0)) { |
| vq_err(vq, "Translation failure %d indirect idx %d\n", |
| ret, i); |
| return ret; |
| } |
| /* If this is an input descriptor, increment that count. */ |
| if (desc.flags & VRING_DESC_F_WRITE) { |
| *in_num += ret; |
| if (unlikely(log)) { |
| log[*log_num].addr = desc.addr; |
| log[*log_num].len = 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(&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_dev *dev, 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; |
| int ret; |
| |
| /* Check it isn't doing very strange things with descriptor numbers. */ |
| last_avail_idx = vq->last_avail_idx; |
| if (unlikely(__get_user(vq->avail_idx, &vq->avail->idx))) { |
| vq_err(vq, "Failed to access avail idx at %p\n", |
| &vq->avail->idx); |
| return -EFAULT; |
| } |
| |
| 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(__get_user(head, |
| &vq->avail->ring[last_avail_idx % vq->num]))) { |
| 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; |
| } |
| |
| /* 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 = __copy_from_user(&desc, vq->desc + i, sizeof desc); |
| if (unlikely(ret)) { |
| vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", |
| i, vq->desc + i); |
| return -EFAULT; |
| } |
| if (desc.flags & VRING_DESC_F_INDIRECT) { |
| ret = get_indirect(dev, vq, iov, iov_size, |
| out_num, in_num, |
| log, log_num, &desc); |
| if (unlikely(ret < 0)) { |
| vq_err(vq, "Failure detected " |
| "in indirect descriptor at idx %d\n", i); |
| return ret; |
| } |
| continue; |
| } |
| |
| ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, |
| iov_size - iov_count); |
| if (unlikely(ret < 0)) { |
| vq_err(vq, "Translation failure %d descriptor idx %d\n", |
| ret, i); |
| return ret; |
| } |
| if (desc.flags & VRING_DESC_F_WRITE) { |
| /* If this is an input descriptor, |
| * increment that count. */ |
| *in_num += ret; |
| if (unlikely(log)) { |
| log[*log_num].addr = desc.addr; |
| log[*log_num].len = 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(&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 = { head, 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) |
| { |
| struct vring_used_elem __user *used; |
| u16 old, new; |
| int start; |
| |
| start = vq->last_used_idx % vq->num; |
| used = vq->used->ring + start; |
| if (count == 1) { |
| if (__put_user(heads[0].id, &used->id)) { |
| vq_err(vq, "Failed to write used id"); |
| return -EFAULT; |
| } |
| if (__put_user(heads[0].len, &used->len)) { |
| vq_err(vq, "Failed to write used len"); |
| return -EFAULT; |
| } |
| } else if (__copy_to_user(used, heads, count * sizeof *used)) { |
| 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_write(vq->log_base, |
| vq->log_addr + |
| ((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; |
| 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 (put_user(vq->last_used_idx, &vq->used->idx)) { |
| vq_err(vq, "Failed to increment used idx"); |
| return -EFAULT; |
| } |
| if (unlikely(vq->log_used)) { |
| /* Log used index update. */ |
| log_write(vq->log_base, |
| vq->log_addr + 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, 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(dev, VIRTIO_F_NOTIFY_ON_EMPTY) && |
| unlikely(vq->avail_idx == vq->last_avail_idx)) |
| return true; |
| |
| if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) { |
| __u16 flags; |
| if (__get_user(flags, &vq->avail->flags)) { |
| vq_err(vq, "Failed to get flags"); |
| return true; |
| } |
| return !(flags & 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 (get_user(event, vhost_used_event(vq))) { |
| vq_err(vq, "Failed to get used event idx"); |
| return true; |
| } |
| return vring_need_event(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); |
| |
| /* OK, now we need to know about added descriptors. */ |
| bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) |
| { |
| u16 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(dev, 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 = __get_user(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 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(dev, 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); |
| |
| 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"); |