linux/drivers/vhost/vhost.c
Linus Torvalds 168fe32a07 Merge branch 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull poll annotations from Al Viro:
 "This introduces a __bitwise type for POLL### bitmap, and propagates
  the annotations through the tree. Most of that stuff is as simple as
  'make ->poll() instances return __poll_t and do the same to local
  variables used to hold the future return value'.

  Some of the obvious brainos found in process are fixed (e.g. POLLIN
  misspelled as POLL_IN). At that point the amount of sparse warnings is
  low and most of them are for genuine bugs - e.g. ->poll() instance
  deciding to return -EINVAL instead of a bitmap. I hadn't touched those
  in this series - it's large enough as it is.

  Another problem it has caught was eventpoll() ABI mess; select.c and
  eventpoll.c assumed that corresponding POLL### and EPOLL### were
  equal. That's true for some, but not all of them - EPOLL### are
  arch-independent, but POLL### are not.

  The last commit in this series separates userland POLL### values from
  the (now arch-independent) kernel-side ones, converting between them
  in the few places where they are copied to/from userland. AFAICS, this
  is the least disruptive fix preserving poll(2) ABI and making epoll()
  work on all architectures.

  As it is, it's simply broken on sparc - try to give it EPOLLWRNORM and
  it will trigger only on what would've triggered EPOLLWRBAND on other
  architectures. EPOLLWRBAND and EPOLLRDHUP, OTOH, are never triggered
  at all on sparc. With this patch they should work consistently on all
  architectures"

* 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (37 commits)
  make kernel-side POLL... arch-independent
  eventpoll: no need to mask the result of epi_item_poll() again
  eventpoll: constify struct epoll_event pointers
  debugging printk in sg_poll() uses %x to print POLL... bitmap
  annotate poll(2) guts
  9p: untangle ->poll() mess
  ->si_band gets POLL... bitmap stored into a user-visible long field
  ring_buffer_poll_wait() return value used as return value of ->poll()
  the rest of drivers/*: annotate ->poll() instances
  media: annotate ->poll() instances
  fs: annotate ->poll() instances
  ipc, kernel, mm: annotate ->poll() instances
  net: annotate ->poll() instances
  apparmor: annotate ->poll() instances
  tomoyo: annotate ->poll() instances
  sound: annotate ->poll() instances
  acpi: annotate ->poll() instances
  crypto: annotate ->poll() instances
  block: annotate ->poll() instances
  x86: annotate ->poll() instances
  ...
2018-01-30 17:58:07 -08:00

2433 lines
59 KiB
C

/* 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/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 "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])
INTERVAL_TREE_DEFINE(struct vhost_umem_node,
rb, __u64, __subtree_last,
START, LAST, static inline, vhost_umem_interval_tree);
#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);
if (!(key_to_poll(key) & poll->mask))
return 0;
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;
init_waitqueue_head(&work->done);
}
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;
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, poll_to_key(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);
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->log_base = NULL;
vq->error_ctx = NULL;
vq->error = NULL;
vq->kick = NULL;
vq->call_ctx = NULL;
vq->call = 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;
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);
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);
work->fn(work);
if (need_resched())
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]);
}
void 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->umem = NULL;
dev->iotlb = NULL;
dev->mm = NULL;
dev->worker = NULL;
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,
POLLIN, 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);
/* 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_umem *vhost_dev_reset_owner_prepare(void)
{
return kvzalloc(sizeof(struct vhost_umem), 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_umem *umem)
{
int i;
vhost_dev_cleanup(dev, true);
/* Restore memory to default empty mapping. */
INIT_LIST_HEAD(&umem->umem_list);
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_umem_free(struct vhost_umem *umem,
struct vhost_umem_node *node)
{
vhost_umem_interval_tree_remove(node, &umem->umem_tree);
list_del(&node->link);
kfree(node);
umem->numem--;
}
static void vhost_umem_clean(struct vhost_umem *umem)
{
struct vhost_umem_node *node, *tmp;
if (!umem)
return;
list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
vhost_umem_free(umem, node);
kvfree(umem);
}
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);
}
/* 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 */
vhost_umem_clean(dev->umem);
dev->umem = NULL;
vhost_umem_clean(dev->iotlb);
dev->iotlb = NULL;
vhost_clear_msg(dev);
wake_up_interruptible_poll(&dev->wait, POLLIN | POLLRDNORM);
WARN_ON(!llist_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);
}
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 int vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
int log_all)
{
struct vhost_umem_node *node;
if (!umem)
return 0;
list_for_each_entry(node, &umem->umem_list, link) {
unsigned long a = node->userspace_addr;
if (vhost_overflow(node->userspace_addr, node->size))
return 0;
if (!access_ok(VERIFY_WRITE, (void __user *)a,
node->size))
return 0;
else if (log_all && !log_access_ok(log_base,
node->start,
node->size))
return 0;
}
return 1;
}
static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
u64 addr, unsigned int size,
int type)
{
const struct vhost_umem_node *node = vq->meta_iotlb[type];
if (!node)
return NULL;
return (void *)(uintptr_t)(node->userspace_addr + addr - node->start);
}
/* 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_umem *umem,
int log_all)
{
int i;
for (i = 0; i < d->nvqs; ++i) {
int 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 = 1;
mutex_unlock(&d->vqs[i]->mutex);
if (!ok)
return 0;
}
return 1;
}
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_DESC);
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 *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 = -EFAULT; \
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; \
})
#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 int vhost_new_umem_range(struct vhost_umem *umem,
u64 start, u64 size, u64 end,
u64 userspace_addr, int perm)
{
struct vhost_umem_node *tmp, *node = kmalloc(sizeof(*node), GFP_ATOMIC);
if (!node)
return -ENOMEM;
if (umem->numem == max_iotlb_entries) {
tmp = list_first_entry(&umem->umem_list, typeof(*tmp), link);
vhost_umem_free(umem, tmp);
}
node->start = start;
node->size = size;
node->last = end;
node->userspace_addr = userspace_addr;
node->perm = perm;
INIT_LIST_HEAD(&node->link);
list_add_tail(&node->link, &umem->umem_list);
vhost_umem_interval_tree_insert(node, &umem->umem_tree);
umem->numem++;
return 0;
}
static void vhost_del_umem_range(struct vhost_umem *umem,
u64 start, u64 end)
{
struct vhost_umem_node *node;
while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
start, end)))
vhost_umem_free(umem, node);
}
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 int 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 -EFAULT;
if ((access & VHOST_ACCESS_RO) &&
!access_ok(VERIFY_READ, (void __user *)a, size))
return -EFAULT;
if ((access & VHOST_ACCESS_WO) &&
!access_ok(VERIFY_WRITE, (void __user *)a, size))
return -EFAULT;
return 0;
}
static int vhost_process_iotlb_msg(struct vhost_dev *dev,
struct vhost_iotlb_msg *msg)
{
int ret = 0;
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_new_umem_range(dev->iotlb, msg->iova, msg->size,
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_del_umem_range(dev->iotlb, msg->iova,
msg->iova + msg->size - 1);
break;
default:
ret = -EINVAL;
break;
}
vhost_dev_unlock_vqs(dev);
return ret;
}
ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
struct iov_iter *from)
{
struct vhost_msg_node node;
unsigned size = sizeof(struct vhost_msg);
size_t ret;
int err;
if (iov_iter_count(from) < size)
return 0;
ret = copy_from_iter(&node.msg, size, from);
if (ret != size)
goto done;
switch (node.msg.type) {
case VHOST_IOTLB_MSG:
err = vhost_process_iotlb_msg(dev, &node.msg.iotlb);
if (err)
ret = err;
break;
default:
ret = -EINVAL;
break;
}
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 |= POLLIN | POLLRDNORM;
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) {
ret = copy_to_iter(&node->msg, size, to);
if (ret != size || node->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;
node = vhost_new_msg(vq, VHOST_IOTLB_MISS);
if (!node)
return -ENOMEM;
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 int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
struct vring_desc __user *desc,
struct vring_avail __user *avail,
struct vring_used __user *used)
{
size_t s = vhost_has_feature(vq, 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);
}
static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
const struct vhost_umem_node *node,
int type)
{
int access = (type == VHOST_ADDR_USED) ?
VHOST_ACCESS_WO : VHOST_ACCESS_RO;
if (likely(node->perm & access))
vq->meta_iotlb[type] = node;
}
static int iotlb_access_ok(struct vhost_virtqueue *vq,
int access, u64 addr, u64 len, int type)
{
const struct vhost_umem_node *node;
struct vhost_umem *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) {
node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
addr,
last);
if (node == NULL || node->start > addr) {
vhost_iotlb_miss(vq, addr, access);
return false;
} else if (!(node->perm & access)) {
/* Report the possible access violation by
* request another translation from userspace.
*/
return false;
}
size = node->size - addr + node->start;
if (orig_addr == addr && size >= len)
vhost_vq_meta_update(vq, node, type);
s += size;
addr += size;
}
return true;
}
int vq_iotlb_prefetch(struct vhost_virtqueue *vq)
{
size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
unsigned int num = vq->num;
if (!vq->iotlb)
return 1;
return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
num * sizeof(*vq->desc), VHOST_ADDR_DESC) &&
iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
sizeof *vq->avail +
num * sizeof(*vq->avail->ring) + s,
VHOST_ADDR_AVAIL) &&
iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
sizeof *vq->used +
num * sizeof(*vq->used->ring) + s,
VHOST_ADDR_USED);
}
EXPORT_SYMBOL_GPL(vq_iotlb_prefetch);
/* Can we log writes? */
/* Caller should have device mutex but not vq mutex */
int 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 int vq_log_access_ok(struct vhost_virtqueue *vq,
void __user *log_base)
{
size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
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,
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)
{
if (vq->iotlb) {
/* When device IOTLB was used, the access validation
* will be validated during prefetching.
*/
return 1;
}
return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
vq_log_access_ok(vq, vq->log_base);
}
EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
static struct vhost_umem *vhost_umem_alloc(void)
{
struct vhost_umem *umem = kvzalloc(sizeof(*umem), GFP_KERNEL);
if (!umem)
return NULL;
umem->umem_tree = RB_ROOT_CACHED;
umem->numem = 0;
INIT_LIST_HEAD(&umem->umem_list);
return umem;
}
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_umem *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(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)) {
kvfree(newmem);
return -EFAULT;
}
newumem = vhost_umem_alloc();
if (!newumem) {
kvfree(newmem);
return -ENOMEM;
}
for (region = newmem->regions;
region < newmem->regions + mem.nregions;
region++) {
if (vhost_new_umem_range(newumem,
region->guest_phys_addr,
region->memory_size,
region->guest_phys_addr +
region->memory_size - 1,
region->userspace_addr,
VHOST_ACCESS_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_umem_clean(oldumem);
return 0;
err:
vhost_umem_clean(newumem);
kvfree(newmem);
return -EFAULT;
}
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;
}
/* 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))) {
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(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)) {
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;
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 (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_umem *niotlb, *oiotlb;
int i;
niotlb = vhost_umem_alloc();
if (!niotlb)
return -ENOMEM;
oiotlb = d->iotlb;
d->iotlb = niotlb;
for (i = 0; i < d->nvqs; ++i) {
mutex_lock(&d->vqs[i]->mutex);
d->vqs[i]->iotlb = niotlb;
mutex_unlock(&d->vqs[i]->mutex);
}
vhost_umem_clean(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 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(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;
d->log_file = eventfp;
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);
/* 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 (vhost_put_user(vq, cpu_to_vhost16(vq, 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 (vhost_put_user(vq, cpu_to_vhost16(vq, 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_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(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) {
r = -EFAULT;
goto err;
}
r = vhost_get_used(vq, last_used_idx, &vq->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_umem_node *node;
struct vhost_dev *dev = vq->dev;
struct vhost_umem *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;
}
node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
addr, addr + len - 1);
if (node == NULL || node->start > addr) {
if (umem != dev->iotlb) {
ret = -EFAULT;
break;
}
ret = -EAGAIN;
break;
} else if (!(node->perm & access)) {
ret = -EPERM;
break;
}
_iov = iov + ret;
size = node->size - addr + node->start;
_iov->iov_len = min((u64)len - s, size);
_iov->iov_base = (void __user *)(unsigned long)
(node->userspace_addr + addr - node->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)) {
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(vq, 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(vq, ring_head,
&vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
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_copy_from_user(vq, &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 & 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)) {
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)
{
struct vring_used_elem __user *used;
u16 old, new;
int start;
start = vq->last_used_idx & (vq->num - 1);
used = vq->used->ring + start;
if (count == 1) {
if (vhost_put_user(vq, heads[0].id, &used->id)) {
vq_err(vq, "Failed to write used id");
return -EFAULT;
}
if (vhost_put_user(vq, heads[0].len, &used->len)) {
vq_err(vq, "Failed to write used len");
return -EFAULT;
}
} else if (vhost_copy_to_user(vq, 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 - 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_user(vq, cpu_to_vhost16(vq, 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;
__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(vq, flags, &vq->avail->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_avail(vq, event, vhost_used_event(vq))) {
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(vq, 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(vq, 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;
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, POLLIN | POLLRDNORM);
}
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");