vhost.c 41.8 KB
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/* 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
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 * Documentation/virtual/lguest/lguest.c, by Rusty Russell
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 *
 * 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>
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#include <linux/uio.h>
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#include <linux/mm.h>
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#include <linux/mmu_context.h>
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#include <linux/miscdevice.h>
#include <linux/mutex.h>
#include <linux/poll.h>
#include <linux/file.h>
#include <linux/highmem.h>
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#include <linux/slab.h>
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#include <linux/kthread.h>
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#include <linux/cgroup.h>
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#include <linux/module.h>
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#include "vhost.h"

enum {
	VHOST_MEMORY_MAX_NREGIONS = 64,
	VHOST_MEMORY_F_LOG = 0x1,
};

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#define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
#define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
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#ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
static void vhost_vq_reset_user_be(struct vhost_virtqueue *vq)
{
	vq->user_be = !virtio_legacy_is_little_endian();
}

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;

	vq->user_be = s.num;

	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_vq_reset_user_be(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)
{
	if (vhost_has_feature(vq, VIRTIO_F_VERSION_1))
		vq->is_le = true;
}
#endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */

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static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
			    poll_table *pt)
{
	struct vhost_poll *poll;

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	poll = container_of(pt, struct vhost_poll, table);
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	poll->wqh = wqh;
	add_wait_queue(wqh, &poll->wait);
}

static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync,
			     void *key)
{
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	struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);

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	if (!((unsigned long)key & poll->mask))
		return 0;

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	vhost_poll_queue(poll);
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	return 0;
}

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void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
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{
	INIT_LIST_HEAD(&work->node);
	work->fn = fn;
	init_waitqueue_head(&work->done);
	work->flushing = 0;
	work->queue_seq = work->done_seq = 0;
}
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EXPORT_SYMBOL_GPL(vhost_work_init);
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/* Init poll structure */
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void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
		     unsigned long mask, struct vhost_dev *dev)
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{
	init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
	init_poll_funcptr(&poll->table, vhost_poll_func);
	poll->mask = mask;
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	poll->dev = dev;
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	poll->wqh = NULL;
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	vhost_work_init(&poll->work, fn);
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}
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EXPORT_SYMBOL_GPL(vhost_poll_init);
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/* 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. */
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int vhost_poll_start(struct vhost_poll *poll, struct file *file)
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{
	unsigned long mask;
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	int ret = 0;
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	if (poll->wqh)
		return 0;

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	mask = file->f_op->poll(file, &poll->table);
	if (mask)
		vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
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	if (mask & POLLERR) {
		if (poll->wqh)
			remove_wait_queue(poll->wqh, &poll->wait);
		ret = -EINVAL;
	}

	return ret;
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}
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EXPORT_SYMBOL_GPL(vhost_poll_start);
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/* 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)
{
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	if (poll->wqh) {
		remove_wait_queue(poll->wqh, &poll->wait);
		poll->wqh = NULL;
	}
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}
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EXPORT_SYMBOL_GPL(vhost_poll_stop);
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static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work,
				unsigned seq)
{
	int left;
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	spin_lock_irq(&dev->work_lock);
	left = seq - work->done_seq;
	spin_unlock_irq(&dev->work_lock);
	return left <= 0;
}

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void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
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{
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	unsigned seq;
	int flushing;

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	spin_lock_irq(&dev->work_lock);
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	seq = work->queue_seq;
	work->flushing++;
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	spin_unlock_irq(&dev->work_lock);
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	wait_event(work->done, vhost_work_seq_done(dev, work, seq));
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	spin_lock_irq(&dev->work_lock);
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	flushing = --work->flushing;
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	spin_unlock_irq(&dev->work_lock);
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	BUG_ON(flushing < 0);
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}
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EXPORT_SYMBOL_GPL(vhost_work_flush);
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/* 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);
}
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EXPORT_SYMBOL_GPL(vhost_poll_flush);
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void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
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{
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	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++;
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		spin_unlock_irqrestore(&dev->work_lock, flags);
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		wake_up_process(dev->worker);
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	} else {
		spin_unlock_irqrestore(&dev->work_lock, flags);
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	}
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}
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EXPORT_SYMBOL_GPL(vhost_work_queue);
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void vhost_poll_queue(struct vhost_poll *poll)
{
	vhost_work_queue(poll->dev, &poll->work);
}
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EXPORT_SYMBOL_GPL(vhost_poll_queue);
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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;
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	vq->signalled_used = 0;
	vq->signalled_used_valid = false;
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	vq->used_flags = 0;
	vq->log_used = false;
	vq->log_addr = -1ull;
	vq->private_data = NULL;
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	vq->acked_features = 0;
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	vq->log_base = NULL;
	vq->error_ctx = NULL;
	vq->error = NULL;
	vq->kick = NULL;
	vq->call_ctx = NULL;
	vq->call = NULL;
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	vq->log_ctx = NULL;
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	vq->memory = NULL;
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	vq->is_le = virtio_legacy_is_little_endian();
	vhost_vq_reset_user_be(vq);
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}

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static int vhost_worker(void *data)
{
	struct vhost_dev *dev = data;
	struct vhost_work *work = NULL;
	unsigned uninitialized_var(seq);
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	mm_segment_t oldfs = get_fs();
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	set_fs(USER_DS);
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	use_mm(dev->mm);

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	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);
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			break;
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		}
		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);
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			if (need_resched())
				schedule();
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		} else
			schedule();

	}
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	unuse_mm(dev->mm);
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	set_fs(oldfs);
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	return 0;
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}

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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;
}

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/* Helper to allocate iovec buffers for all vqs. */
static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
{
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	struct vhost_virtqueue *vq;
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	int i;
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	for (i = 0; i < dev->nvqs; ++i) {
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		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)
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			goto err_nomem;
	}
	return 0;
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err_nomem:
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	for (; i >= 0; --i)
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		vhost_vq_free_iovecs(dev->vqs[i]);
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	return -ENOMEM;
}

static void vhost_dev_free_iovecs(struct vhost_dev *dev)
{
	int i;
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	for (i = 0; i < dev->nvqs; ++i)
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		vhost_vq_free_iovecs(dev->vqs[i]);
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}

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void vhost_dev_init(struct vhost_dev *dev,
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		    struct vhost_virtqueue **vqs, int nvqs)
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{
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	struct vhost_virtqueue *vq;
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	int i;
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	dev->vqs = vqs;
	dev->nvqs = nvqs;
	mutex_init(&dev->mutex);
	dev->log_ctx = NULL;
	dev->log_file = NULL;
	dev->memory = NULL;
	dev->mm = NULL;
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	spin_lock_init(&dev->work_lock);
	INIT_LIST_HEAD(&dev->work_list);
	dev->worker = NULL;
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	for (i = 0; i < dev->nvqs; ++i) {
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		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);
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	}
}
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EXPORT_SYMBOL_GPL(vhost_dev_init);
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/* 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;
}
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EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
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struct vhost_attach_cgroups_struct {
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	struct vhost_work work;
	struct task_struct *owner;
	int ret;
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};

static void vhost_attach_cgroups_work(struct vhost_work *work)
{
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	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);
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}

static int vhost_attach_cgroups(struct vhost_dev *dev)
{
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	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;
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}

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/* Caller should have device mutex */
bool vhost_dev_has_owner(struct vhost_dev *dev)
{
	return dev->mm;
}
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EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
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/* Caller should have device mutex */
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long vhost_dev_set_owner(struct vhost_dev *dev)
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{
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	struct task_struct *worker;
	int err;
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	/* Is there an owner already? */
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	if (vhost_dev_has_owner(dev)) {
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		err = -EBUSY;
		goto err_mm;
	}
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	/* No owner, become one */
	dev->mm = get_task_mm(current);
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	worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
	if (IS_ERR(worker)) {
		err = PTR_ERR(worker);
		goto err_worker;
	}

	dev->worker = worker;
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	wake_up_process(worker);	/* avoid contributing to loadavg */

	err = vhost_attach_cgroups(dev);
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	if (err)
		goto err_cgroup;
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	err = vhost_dev_alloc_iovecs(dev);
	if (err)
		goto err_cgroup;

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	return 0;
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err_cgroup:
	kthread_stop(worker);
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	dev->worker = NULL;
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err_worker:
	if (dev->mm)
		mmput(dev->mm);
	dev->mm = NULL;
err_mm:
	return err;
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}
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EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
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struct vhost_memory *vhost_dev_reset_owner_prepare(void)
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{
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	return kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
}
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EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
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/* Caller should have device mutex */
void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_memory *memory)
{
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	int i;

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	vhost_dev_cleanup(dev, true);
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	/* Restore memory to default empty mapping. */
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	memory->nregions = 0;
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	dev->memory = memory;
	/* 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]->memory = memory;
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}
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EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
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void vhost_dev_stop(struct vhost_dev *dev)
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{
	int i;
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	for (i = 0; i < dev->nvqs; ++i) {
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		if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
			vhost_poll_stop(&dev->vqs[i]->poll);
			vhost_poll_flush(&dev->vqs[i]->poll);
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		}
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	}
}
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EXPORT_SYMBOL_GPL(vhost_dev_stop);
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/* Caller should have device mutex if and only if locked is set */
void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
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{
	int i;
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	for (i = 0; i < dev->nvqs; ++i) {
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		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]);
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	}
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	vhost_dev_free_iovecs(dev);
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	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 */
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	kfree(dev->memory);
	dev->memory = NULL;
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	WARN_ON(!list_empty(&dev->work_list));
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	if (dev->worker) {
		kthread_stop(dev->worker);
		dev->worker = NULL;
	}
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	if (dev->mm)
		mmput(dev->mm);
	dev->mm = NULL;
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}
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EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
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static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
{
	u64 a = addr / VHOST_PAGE_SIZE / 8;
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	/* Make sure 64 bit math will not overflow. */
	if (a > ULONG_MAX - (unsigned long)log_base ||
	    a + (unsigned long)log_base > ULONG_MAX)
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		return 0;
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	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;
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	if (!mem)
		return 0;
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	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;
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	for (i = 0; i < d->nvqs; ++i) {
		int ok;
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		bool log;

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		mutex_lock(&d->vqs[i]->mutex);
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		log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
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		/* If ring is inactive, will check when it's enabled. */
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		if (d->vqs[i]->private_data)
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			ok = vq_memory_access_ok(d->vqs[i]->log_base, mem, log);
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		else
			ok = 1;
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		mutex_unlock(&d->vqs[i]->mutex);
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		if (!ok)
			return 0;
	}
	return 1;
}

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static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
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			struct vring_desc __user *desc,
			struct vring_avail __user *avail,
			struct vring_used __user *used)
{
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	size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
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	return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
	       access_ok(VERIFY_READ, avail,
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			 sizeof *avail + num * sizeof *avail->ring + s) &&
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	       access_ok(VERIFY_WRITE, used,
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			sizeof *used + num * sizeof *used->ring + s);
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}

/* Can we log writes? */
/* Caller should have device mutex but not vq mutex */
int vhost_log_access_ok(struct vhost_dev *dev)
{
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	return memory_access_ok(dev, dev->memory, 1);
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}
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EXPORT_SYMBOL_GPL(vhost_log_access_ok);
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/* Verify access for write logging. */
/* Caller should have vq mutex and device mutex */
645
static int vq_log_access_ok(struct vhost_virtqueue *vq,
646
			    void __user *log_base)
647
{
648
	size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
Arnd Bergmann's avatar
Arnd Bergmann committed
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650
	return vq_memory_access_ok(log_base, vq->memory,
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				   vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
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		(!vq->log_used || log_access_ok(log_base, vq->log_addr,
					sizeof *vq->used +
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					vq->num * sizeof *vq->used->ring + s));
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}

/* Can we start vq? */
/* Caller should have vq mutex and device mutex */
int vhost_vq_access_ok(struct vhost_virtqueue *vq)
{
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	return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
		vq_log_access_ok(vq, vq->log_base);
663
}
664
EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
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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);
670
	int i;
671

672 673
	if (copy_from_user(&mem, m, size))
		return -EFAULT;
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	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);
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	if (copy_from_user(newmem->regions, m->regions,
			   mem.nregions * sizeof *m->regions)) {
685
		kfree(newmem);
686
		return -EFAULT;
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	}

689
	if (!memory_access_ok(d, newmem, 0)) {
690
		kfree(newmem);
691
		return -EFAULT;
692
	}
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	oldmem = d->memory;
	d->memory = newmem;
695

696
	/* All memory accesses are done under some VQ mutex. */
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	for (i = 0; i < d->nvqs; ++i) {
		mutex_lock(&d->vqs[i]->mutex);
699
		d->vqs[i]->memory = newmem;
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		mutex_unlock(&d->vqs[i]->mutex);
	}
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	kfree(oldmem);
	return 0;
}

706
long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
707
{
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	struct file *eventfp, *filep = NULL;
	bool pollstart = false, pollstop = false;
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	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;
722
	if (idx >= d->nvqs)
723 724
		return -ENOBUFS;

725
	vq = d->vqs[idx];
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	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;
		}
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		if (copy_from_user(&s, argp, sizeof s)) {
			r = -EFAULT;
739
			break;
740
		}
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		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;
		}
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		if (copy_from_user(&s, argp, sizeof s)) {
			r = -EFAULT;
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			break;
757
		}
758 759 760 761 762 763 764 765 766 767 768
		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;
769 770
		if (copy_to_user(argp, &s, sizeof s))
			r = -EFAULT;
771 772
		break;
	case VHOST_SET_VRING_ADDR:
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		if (copy_from_user(&a, argp, sizeof a)) {
			r = -EFAULT;
775
			break;
776
		}
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		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;
		}
789 790 791 792 793 794 795

		/* 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 & (sizeof(u64) - 1))) {
796 797 798 799 800 801 802 803
			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) {
804
			if (!vq_access_ok(vq, vq->num,
805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828
				(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:
829 830
		if (copy_from_user(&f, argp, sizeof f)) {
			r = -EFAULT;
831
			break;
832
		}
833
		eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
834 835 836 837
		if (IS_ERR(eventfp)) {
			r = PTR_ERR(eventfp);
			break;
		}
838
		if (eventfp != vq->kick) {
839 840
			pollstop = (filep = vq->kick) != NULL;
			pollstart = (vq->kick = eventfp) != NULL;
841 842 843 844
		} else
			filep = eventfp;
		break;
	case VHOST_SET_VRING_CALL:
845 846
		if (copy_from_user(&f, argp, sizeof f)) {
			r = -EFAULT;
847
			break;
848
		}
849
		eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
850 851 852 853
		if (IS_ERR(eventfp)) {
			r = PTR_ERR(eventfp);
			break;
		}
854 855 856 857 858 859 860 861 862 863
		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:
864 865
		if (copy_from_user(&f, argp, sizeof f)) {
			r = -EFAULT;
866
			break;
867
		}
868
		eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
869 870 871 872
		if (IS_ERR(eventfp)) {
			r = PTR_ERR(eventfp);
			break;
		}
873 874 875 876 877 878 879 880 881
		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;
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	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;
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	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)
901
		r = vhost_poll_start(&vq->poll, vq->kick);
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	mutex_unlock(&vq->mutex);

	if (pollstop && vq->handle_kick)
		vhost_poll_flush(&vq->poll);
	return r;
}
909
EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
910 911

/* Caller must have device mutex */
912
long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935
{
	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:
936 937
		if (copy_from_user(&p, argp, sizeof p)) {
			r = -EFAULT;
938
			break;
939
		}
940 941 942 943 944 945 946
		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;
947
			vq = d->vqs[i];
948 949
			mutex_lock(&vq->mutex);
			/* If ring is inactive, will check when it's enabled. */
950
			if (vq->private_data && !vq_log_access_ok(vq, base))
951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973
				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) {
974 975 976
			mutex_lock(&d->vqs[i]->mutex);
			d->vqs[i]->log_ctx = d->log_ctx;
			mutex_unlock(&d->vqs[i]->mutex);
977 978 979 980 981 982 983
		}
		if (ctx)
			eventfd_ctx_put(ctx);
		if (filep)
			fput(filep);
		break;
	default:
984
		r = -ENOIOCTLCMD;
985 986 987 988 989
		break;
	}
done:
	return r;
}
990
EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
991 992 993 994 995 996

static const struct vhost_memory_region *find_region(struct vhost_memory *mem,
						     __u64 addr, __u32 len)
{
	struct vhost_memory_region *reg;
	int i;
997

998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019
	/* 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;
1020

1021
	r = get_user_pages_fast(log, 1, 1, &page);
1022
	if (r < 0)
1023
		return r;
1024
	BUG_ON(r != 1);
1025
	base = kmap_atomic(page);
1026
	set_bit(bit, base);
1027
	kunmap_atomic(base);
1028 1029 1030 1031 1032 1033 1034 1035
	set_page_dirty_lock(page);
	put_page(page);
	return 0;
}

static int log_write(void __user *log_base,
		     u64 write_address, u64 write_length)
{
1036
	u64 write_page = write_address / VHOST_PAGE_SIZE;
1037
	int r;
1038

1039 1040
	if (!write_length)
		return 0;
1041
	write_length += write_address % VHOST_PAGE_SIZE;
1042 1043
	for (;;) {
		u64 base = (u64)(unsigned long)log_base;
1044 1045
		u64 log = base + write_page / 8;
		int bit = write_page % 8;
1046 1047 1048 1049 1050 1051 1052 1053
		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;
1054
		write_page += 1;
1055 1056 1057 1058 1059 1060 1061 1062 1063 1064
	}
	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. */
1065
	smp_wmb();
1066 1067 1068 1069 1070 1071
	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;
1072 1073 1074
		if (!len) {
			if (vq->log_ctx)
				eventfd_signal(vq->log_ctx, 1);
1075
			return 0;
1076
		}
1077 1078 1079 1080 1081
	}
	/* Length written exceeds what we have stored. This is a bug. */
	BUG();
	return 0;
}
1082
EXPORT_SYMBOL_GPL(vhost_log_write);
1083

1084 1085 1086
static int vhost_update_used_flags(struct vhost_virtqueue *vq)
{
	void __user *used;
1087
	if (__put_user(cpu_to_vhost16(vq, vq->used_flags), &vq->used->flags) < 0)
1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104
		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)
{
1105
	if (__put_user(cpu_to_vhost16(vq, vq->avail_idx), vhost_avail_event(vq)))
1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123
		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)
{
1124
	__virtio16 last_used_idx;
1125
	int r;
1126 1127
	if (!vq->private_data) {
		vq->is_le = virtio_legacy_is_little_endian();
1128
		return 0;
1129 1130 1131
	}

	vhost_init_is_le(vq);
1132 1133 1134 1135 1136

	r = vhost_update_used_flags(vq);
	if (r)
		return r;
	vq->signalled_used_valid = false;
1137 1138 1139 1140 1141
	if (!access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx))
		return -EFAULT;
	r = __get_user(last_used_idx, &vq->used->idx);
	if (r)
		return r;
1142
	vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1143
	return 0;
1144
}
1145
EXPORT_SYMBOL_GPL(vhost_init_used);
1146

1147
static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1148
			  struct iovec iov[], int iov_size)
1149 1150 1151 1152 1153 1154 1155
{
	const struct vhost_memory_region *reg;
	struct vhost_memory *mem;
	struct iovec *_iov;
	u64 s = 0;
	int ret = 0;

1156
	mem = vq->memory;
1157 1158
	while ((u64)len > s) {
		u64 size;
1159
		if (unlikely(ret >= iov_size)) {
1160 1161 1162 1163
			ret = -ENOBUFS;
			break;
		}
		reg = find_region(mem, addr, len);
1164
		if (unlikely(!reg)) {
1165 1166 1167 1168 1169
			ret = -EFAULT;
			break;
		}
		_iov = iov + ret;
		size = reg->memory_size - addr + reg->guest_phys_addr;
1170
		_iov->iov_len = min((u64)len - s, size);
1171
		_iov->iov_base = (void __user *)(unsigned long)
1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183
			(reg->userspace_addr + addr - reg->guest_phys_addr);
		s += size;
		addr += size;
		++ret;
	}

	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. */
1184
static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1185 1186 1187 1188
{
	unsigned int next;

	/* If this descriptor says it doesn't chain, we're done. */
1189
	if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1190 1191 1192
		return -1U;

	/* Check they're not leading us off end of descriptors. */
1193
	next = vhost16_to_cpu(vq, desc->next);
1194 1195 1196 1197 1198 1199 1200 1201
	/* 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;
}

1202
static int get_indirect(struct vhost_virtqueue *vq,
1203 1204 1205 1206
			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)
1207 1208 1209
{
	struct vring_desc desc;
	unsigned int i = 0, count, found = 0;
1210
	u32 len = vhost32_to_cpu(vq, indirect->len);
1211
	struct iov_iter from;
1212 1213 1214
	int ret;

	/* Sanity check */
1215
	if (unlikely(len % sizeof desc)) {
1216 1217
		vq_err(vq, "Invalid length in indirect descriptor: "
		       "len 0x%llx not multiple of 0x%zx\n",
1218
		       (unsigned long long)len,
1219 1220 1221 1222
		       sizeof desc);
		return -EINVAL;
	}

1223
	ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,