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linux/drivers/vhost/vhost.c
Mike Christie 228a27cf78 vhost: Allow worker switching while work is queueing 
This patch drops the requirement that we can only switch workers if work
has not been queued by using RCU for the vq based queueing paths and a
mutex for the device wide flush.

We can also use this to support SIGKILL properly in the future where we
should exit almost immediately after getting that signal. With this
patch, when get_signal returns true, we can set the vq->worker to NULL
and do a synchronize_rcu to prevent new work from being queued to the
vhost_task that has been killed.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20230626232307.97930-18-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2023-07-03 12:15:14 -04:00

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// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (C) 2009 Red Hat, Inc.
* Copyright (C) 2006 Rusty Russell IBM Corporation
*
* Author: Michael S. Tsirkin <mst@redhat.com>
*
* Inspiration, some code, and most witty comments come from
* Documentation/virtual/lguest/lguest.c, by Rusty Russell
*
* Generic code for virtio server in host kernel.
*/
#include <linux/eventfd.h>
#include <linux/vhost.h>
#include <linux/uio.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/mutex.h>
#include <linux/poll.h>
#include <linux/file.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/sort.h>
#include <linux/sched/mm.h>
#include <linux/sched/signal.h>
#include <linux/sched/vhost_task.h>
#include <linux/interval_tree_generic.h>
#include <linux/nospec.h>
#include <linux/kcov.h>
#include "vhost.h"
static ushort max_mem_regions = 64;
module_param(max_mem_regions, ushort, 0444);
MODULE_PARM_DESC(max_mem_regions,
"Maximum number of memory regions in memory map. (default: 64)");
static int max_iotlb_entries = 2048;
module_param(max_iotlb_entries, int, 0444);
MODULE_PARM_DESC(max_iotlb_entries,
"Maximum number of iotlb entries. (default: 2048)");
enum {
VHOST_MEMORY_F_LOG = 0x1,
};
#define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
#define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
#ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
{
vq->user_be = !virtio_legacy_is_little_endian();
}
static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
{
vq->user_be = true;
}
static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
{
vq->user_be = false;
}
static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
{
struct vhost_vring_state s;
if (vq->private_data)
return -EBUSY;
if (copy_from_user(&s, argp, sizeof(s)))
return -EFAULT;
if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
s.num != VHOST_VRING_BIG_ENDIAN)
return -EINVAL;
if (s.num == VHOST_VRING_BIG_ENDIAN)
vhost_enable_cross_endian_big(vq);
else
vhost_enable_cross_endian_little(vq);
return 0;
}
static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
int __user *argp)
{
struct vhost_vring_state s = {
.index = idx,
.num = vq->user_be
};
if (copy_to_user(argp, &s, sizeof(s)))
return -EFAULT;
return 0;
}
static void vhost_init_is_le(struct vhost_virtqueue *vq)
{
/* Note for legacy virtio: user_be is initialized at reset time
* according to the host endianness. If userspace does not set an
* explicit endianness, the default behavior is native endian, as
* expected by legacy virtio.
*/
vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
}
#else
static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
{
}
static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
{
return -ENOIOCTLCMD;
}
static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
int __user *argp)
{
return -ENOIOCTLCMD;
}
static void vhost_init_is_le(struct vhost_virtqueue *vq)
{
vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1)
|| virtio_legacy_is_little_endian();
}
#endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
static void vhost_reset_is_le(struct vhost_virtqueue *vq)
{
vhost_init_is_le(vq);
}
struct vhost_flush_struct {
struct vhost_work work;
struct completion wait_event;
};
static void vhost_flush_work(struct vhost_work *work)
{
struct vhost_flush_struct *s;
s = container_of(work, struct vhost_flush_struct, work);
complete(&s->wait_event);
}
static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
poll_table *pt)
{
struct vhost_poll *poll;
poll = container_of(pt, struct vhost_poll, table);
poll->wqh = wqh;
add_wait_queue(wqh, &poll->wait);
}
static int vhost_poll_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync,
void *key)
{
struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
struct vhost_work *work = &poll->work;
if (!(key_to_poll(key) & poll->mask))
return 0;
if (!poll->dev->use_worker)
work->fn(work);
else
vhost_poll_queue(poll);
return 0;
}
void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
{
clear_bit(VHOST_WORK_QUEUED, &work->flags);
work->fn = fn;
}
EXPORT_SYMBOL_GPL(vhost_work_init);
/* Init poll structure */
void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
__poll_t mask, struct vhost_dev *dev,
struct vhost_virtqueue *vq)
{
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;
poll->vq = vq;
vhost_work_init(&poll->work, fn);
}
EXPORT_SYMBOL_GPL(vhost_poll_init);
/* Start polling a file. We add ourselves to file's wait queue. The caller must
* keep a reference to a file until after vhost_poll_stop is called. */
int vhost_poll_start(struct vhost_poll *poll, struct file *file)
{
__poll_t mask;
if (poll->wqh)
return 0;
mask = vfs_poll(file, &poll->table);
if (mask)
vhost_poll_wakeup(&poll->wait, 0, 0, poll_to_key(mask));
if (mask & EPOLLERR) {
vhost_poll_stop(poll);
return -EINVAL;
}
return 0;
}
EXPORT_SYMBOL_GPL(vhost_poll_start);
/* Stop polling a file. After this function returns, it becomes safe to drop the
* file reference. You must also flush afterwards. */
void vhost_poll_stop(struct vhost_poll *poll)
{
if (poll->wqh) {
remove_wait_queue(poll->wqh, &poll->wait);
poll->wqh = NULL;
}
}
EXPORT_SYMBOL_GPL(vhost_poll_stop);
static void vhost_worker_queue(struct vhost_worker *worker,
struct vhost_work *work)
{
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, &worker->work_list);
vhost_task_wake(worker->vtsk);
}
}
bool vhost_vq_work_queue(struct vhost_virtqueue *vq, struct vhost_work *work)
{
struct vhost_worker *worker;
bool queued = false;
rcu_read_lock();
worker = rcu_dereference(vq->worker);
if (worker) {
queued = true;
vhost_worker_queue(worker, work);
}
rcu_read_unlock();
return queued;
}
EXPORT_SYMBOL_GPL(vhost_vq_work_queue);
void vhost_vq_flush(struct vhost_virtqueue *vq)
{
struct vhost_flush_struct flush;
init_completion(&flush.wait_event);
vhost_work_init(&flush.work, vhost_flush_work);
if (vhost_vq_work_queue(vq, &flush.work))
wait_for_completion(&flush.wait_event);
}
EXPORT_SYMBOL_GPL(vhost_vq_flush);
/**
* vhost_worker_flush - flush a worker
* @worker: worker to flush
*
* This does not use RCU to protect the worker, so the device or worker
* mutex must be held.
*/
static void vhost_worker_flush(struct vhost_worker *worker)
{
struct vhost_flush_struct flush;
init_completion(&flush.wait_event);
vhost_work_init(&flush.work, vhost_flush_work);
vhost_worker_queue(worker, &flush.work);
wait_for_completion(&flush.wait_event);
}
void vhost_dev_flush(struct vhost_dev *dev)
{
struct vhost_worker *worker;
unsigned long i;
xa_for_each(&dev->worker_xa, i, worker) {
mutex_lock(&worker->mutex);
if (!worker->attachment_cnt) {
mutex_unlock(&worker->mutex);
continue;
}
vhost_worker_flush(worker);
mutex_unlock(&worker->mutex);
}
}
EXPORT_SYMBOL_GPL(vhost_dev_flush);
/* A lockless hint for busy polling code to exit the loop */
bool vhost_vq_has_work(struct vhost_virtqueue *vq)
{
struct vhost_worker *worker;
bool has_work = false;
rcu_read_lock();
worker = rcu_dereference(vq->worker);
if (worker && !llist_empty(&worker->work_list))
has_work = true;
rcu_read_unlock();
return has_work;
}
EXPORT_SYMBOL_GPL(vhost_vq_has_work);
void vhost_poll_queue(struct vhost_poll *poll)
{
vhost_vq_work_queue(poll->vq, &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_vring_call_reset(struct vhost_vring_call *call_ctx)
{
call_ctx->ctx = NULL;
memset(&call_ctx->producer, 0x0, sizeof(struct irq_bypass_producer));
}
bool vhost_vq_is_setup(struct vhost_virtqueue *vq)
{
return vq->avail && vq->desc && vq->used && vhost_vq_access_ok(vq);
}
EXPORT_SYMBOL_GPL(vhost_vq_is_setup);
static void vhost_vq_reset(struct vhost_dev *dev,
struct vhost_virtqueue *vq)
{
vq->num = 1;
vq->desc = NULL;
vq->avail = NULL;
vq->used = NULL;
vq->last_avail_idx = 0;
vq->avail_idx = 0;
vq->last_used_idx = 0;
vq->signalled_used = 0;
vq->signalled_used_valid = false;
vq->used_flags = 0;
vq->log_used = false;
vq->log_addr = -1ull;
vq->private_data = NULL;
vq->acked_features = 0;
vq->acked_backend_features = 0;
vq->log_base = NULL;
vq->error_ctx = NULL;
vq->kick = NULL;
vq->log_ctx = NULL;
vhost_disable_cross_endian(vq);
vhost_reset_is_le(vq);
vq->busyloop_timeout = 0;
vq->umem = NULL;
vq->iotlb = NULL;
rcu_assign_pointer(vq->worker, NULL);
vhost_vring_call_reset(&vq->call_ctx);
__vhost_vq_meta_reset(vq);
}
static bool vhost_worker(void *data)
{
struct vhost_worker *worker = data;
struct vhost_work *work, *work_next;
struct llist_node *node;
node = llist_del_all(&worker->work_list);
if (node) {
__set_current_state(TASK_RUNNING);
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);
kcov_remote_start_common(worker->kcov_handle);
work->fn(work);
kcov_remote_stop();
cond_resched();
}
}
return !!node;
}
static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
{
kfree(vq->indirect);
vq->indirect = NULL;
kfree(vq->log);
vq->log = NULL;
kfree(vq->heads);
vq->heads = NULL;
}
/* Helper to allocate iovec buffers for all vqs. */
static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
{
struct vhost_virtqueue *vq;
int i;
for (i = 0; i < dev->nvqs; ++i) {
vq = dev->vqs[i];
vq->indirect = kmalloc_array(UIO_MAXIOV,
sizeof(*vq->indirect),
GFP_KERNEL);
vq->log = kmalloc_array(dev->iov_limit, sizeof(*vq->log),
GFP_KERNEL);
vq->heads = kmalloc_array(dev->iov_limit, sizeof(*vq->heads),
GFP_KERNEL);
if (!vq->indirect || !vq->log || !vq->heads)
goto err_nomem;
}
return 0;
err_nomem:
for (; i >= 0; --i)
vhost_vq_free_iovecs(dev->vqs[i]);
return -ENOMEM;
}
static void vhost_dev_free_iovecs(struct vhost_dev *dev)
{
int i;
for (i = 0; i < dev->nvqs; ++i)
vhost_vq_free_iovecs(dev->vqs[i]);
}
bool vhost_exceeds_weight(struct vhost_virtqueue *vq,
int pkts, int total_len)
{
struct vhost_dev *dev = vq->dev;
if ((dev->byte_weight && total_len >= dev->byte_weight) ||
pkts >= dev->weight) {
vhost_poll_queue(&vq->poll);
return true;
}
return false;
}
EXPORT_SYMBOL_GPL(vhost_exceeds_weight);
static size_t vhost_get_avail_size(struct vhost_virtqueue *vq,
unsigned int num)
{
size_t event __maybe_unused =
vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
return size_add(struct_size(vq->avail, ring, num), event);
}
static size_t vhost_get_used_size(struct vhost_virtqueue *vq,
unsigned int num)
{
size_t event __maybe_unused =
vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
return size_add(struct_size(vq->used, ring, num), event);
}
static size_t vhost_get_desc_size(struct vhost_virtqueue *vq,
unsigned int num)
{
return sizeof(*vq->desc) * num;
}
void vhost_dev_init(struct vhost_dev *dev,
struct vhost_virtqueue **vqs, int nvqs,
int iov_limit, int weight, int byte_weight,
bool use_worker,
int (*msg_handler)(struct vhost_dev *dev, u32 asid,
struct vhost_iotlb_msg *msg))
{
struct vhost_virtqueue *vq;
int i;
dev->vqs = vqs;
dev->nvqs = nvqs;
mutex_init(&dev->mutex);
dev->log_ctx = NULL;
dev->umem = NULL;
dev->iotlb = NULL;
dev->mm = NULL;
dev->iov_limit = iov_limit;
dev->weight = weight;
dev->byte_weight = byte_weight;
dev->use_worker = use_worker;
dev->msg_handler = msg_handler;
init_waitqueue_head(&dev->wait);
INIT_LIST_HEAD(&dev->read_list);
INIT_LIST_HEAD(&dev->pending_list);
spin_lock_init(&dev->iotlb_lock);
xa_init_flags(&dev->worker_xa, XA_FLAGS_ALLOC);
for (i = 0; i < dev->nvqs; ++i) {
vq = dev->vqs[i];
vq->log = NULL;
vq->indirect = NULL;
vq->heads = NULL;
vq->dev = dev;
mutex_init(&vq->mutex);
vhost_vq_reset(dev, vq);
if (vq->handle_kick)
vhost_poll_init(&vq->poll, vq->handle_kick,
EPOLLIN, dev, vq);
}
}
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);
/* Caller should have device mutex */
bool vhost_dev_has_owner(struct vhost_dev *dev)
{
return dev->mm;
}
EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
static void vhost_attach_mm(struct vhost_dev *dev)
{
/* No owner, become one */
if (dev->use_worker) {
dev->mm = get_task_mm(current);
} else {
/* vDPA device does not use worker thead, so there's
* no need to hold the address space for mm. This help
* to avoid deadlock in the case of mmap() which may
* held the refcnt of the file and depends on release
* method to remove vma.
*/
dev->mm = current->mm;
mmgrab(dev->mm);
}
}
static void vhost_detach_mm(struct vhost_dev *dev)
{
if (!dev->mm)
return;
if (dev->use_worker)
mmput(dev->mm);
else
mmdrop(dev->mm);
dev->mm = NULL;
}
static void vhost_worker_destroy(struct vhost_dev *dev,
struct vhost_worker *worker)
{
if (!worker)
return;
WARN_ON(!llist_empty(&worker->work_list));
xa_erase(&dev->worker_xa, worker->id);
vhost_task_stop(worker->vtsk);
kfree(worker);
}
static void vhost_workers_free(struct vhost_dev *dev)
{
struct vhost_worker *worker;
unsigned long i;
if (!dev->use_worker)
return;
for (i = 0; i < dev->nvqs; i++)
rcu_assign_pointer(dev->vqs[i]->worker, NULL);
/*
* Free the default worker we created and cleanup workers userspace
* created but couldn't clean up (it forgot or crashed).
*/
xa_for_each(&dev->worker_xa, i, worker)
vhost_worker_destroy(dev, worker);
xa_destroy(&dev->worker_xa);
}
static struct vhost_worker *vhost_worker_create(struct vhost_dev *dev)
{
struct vhost_worker *worker;
struct vhost_task *vtsk;
char name[TASK_COMM_LEN];
int ret;
u32 id;
worker = kzalloc(sizeof(*worker), GFP_KERNEL_ACCOUNT);
if (!worker)
return NULL;
snprintf(name, sizeof(name), "vhost-%d", current->pid);
vtsk = vhost_task_create(vhost_worker, worker, name);
if (!vtsk)
goto free_worker;
mutex_init(&worker->mutex);
init_llist_head(&worker->work_list);
worker->kcov_handle = kcov_common_handle();
worker->vtsk = vtsk;
vhost_task_start(vtsk);
ret = xa_alloc(&dev->worker_xa, &id, worker, xa_limit_32b, GFP_KERNEL);
if (ret < 0)
goto stop_worker;
worker->id = id;
return worker;
stop_worker:
vhost_task_stop(vtsk);
free_worker:
kfree(worker);
return NULL;
}
/* Caller must have device mutex */
static void __vhost_vq_attach_worker(struct vhost_virtqueue *vq,
struct vhost_worker *worker)
{
struct vhost_worker *old_worker;
old_worker = rcu_dereference_check(vq->worker,
lockdep_is_held(&vq->dev->mutex));
mutex_lock(&worker->mutex);
worker->attachment_cnt++;
mutex_unlock(&worker->mutex);
rcu_assign_pointer(vq->worker, worker);
if (!old_worker)
return;
/*
* Take the worker mutex to make sure we see the work queued from
* device wide flushes which doesn't use RCU for execution.
*/
mutex_lock(&old_worker->mutex);
old_worker->attachment_cnt--;
/*
* We don't want to call synchronize_rcu for every vq during setup
* because it will slow down VM startup. If we haven't done
* VHOST_SET_VRING_KICK and not done the driver specific
* SET_ENDPOINT/RUNNUNG then we can skip the sync since there will
* not be any works queued for scsi and net.
*/
mutex_lock(&vq->mutex);
if (!vhost_vq_get_backend(vq) && !vq->kick) {
mutex_unlock(&vq->mutex);
mutex_unlock(&old_worker->mutex);
/*
* vsock can queue anytime after VHOST_VSOCK_SET_GUEST_CID.
* Warn if it adds support for multiple workers but forgets to
* handle the early queueing case.
*/
WARN_ON(!old_worker->attachment_cnt &&
!llist_empty(&old_worker->work_list));
return;
}
mutex_unlock(&vq->mutex);
/* Make sure new vq queue/flush/poll calls see the new worker */
synchronize_rcu();
/* Make sure whatever was queued gets run */
vhost_worker_flush(old_worker);
mutex_unlock(&old_worker->mutex);
}
/* Caller must have device mutex */
static int vhost_vq_attach_worker(struct vhost_virtqueue *vq,
struct vhost_vring_worker *info)
{
unsigned long index = info->worker_id;
struct vhost_dev *dev = vq->dev;
struct vhost_worker *worker;
if (!dev->use_worker)
return -EINVAL;
worker = xa_find(&dev->worker_xa, &index, UINT_MAX, XA_PRESENT);
if (!worker || worker->id != info->worker_id)
return -ENODEV;
__vhost_vq_attach_worker(vq, worker);
return 0;
}
/* Caller must have device mutex */
static int vhost_new_worker(struct vhost_dev *dev,
struct vhost_worker_state *info)
{
struct vhost_worker *worker;
worker = vhost_worker_create(dev);
if (!worker)
return -ENOMEM;
info->worker_id = worker->id;
return 0;
}
/* Caller must have device mutex */
static int vhost_free_worker(struct vhost_dev *dev,
struct vhost_worker_state *info)
{
unsigned long index = info->worker_id;
struct vhost_worker *worker;
worker = xa_find(&dev->worker_xa, &index, UINT_MAX, XA_PRESENT);
if (!worker || worker->id != info->worker_id)
return -ENODEV;
mutex_lock(&worker->mutex);
if (worker->attachment_cnt) {
mutex_unlock(&worker->mutex);
return -EBUSY;
}
mutex_unlock(&worker->mutex);
vhost_worker_destroy(dev, worker);
return 0;
}
static int vhost_get_vq_from_user(struct vhost_dev *dev, void __user *argp,
struct vhost_virtqueue **vq, u32 *id)
{
u32 __user *idxp = argp;
u32 idx;
long r;
r = get_user(idx, idxp);
if (r < 0)
return r;
if (idx >= dev->nvqs)
return -ENOBUFS;
idx = array_index_nospec(idx, dev->nvqs);
*vq = dev->vqs[idx];
*id = idx;
return 0;
}
/* Caller must have device mutex */
long vhost_worker_ioctl(struct vhost_dev *dev, unsigned int ioctl,
void __user *argp)
{
struct vhost_vring_worker ring_worker;
struct vhost_worker_state state;
struct vhost_worker *worker;
struct vhost_virtqueue *vq;
long ret;
u32 idx;
if (!dev->use_worker)
return -EINVAL;
if (!vhost_dev_has_owner(dev))
return -EINVAL;
ret = vhost_dev_check_owner(dev);
if (ret)
return ret;
switch (ioctl) {
/* dev worker ioctls */
case VHOST_NEW_WORKER:
ret = vhost_new_worker(dev, &state);
if (!ret && copy_to_user(argp, &state, sizeof(state)))
ret = -EFAULT;
return ret;
case VHOST_FREE_WORKER:
if (copy_from_user(&state, argp, sizeof(state)))
return -EFAULT;
return vhost_free_worker(dev, &state);
/* vring worker ioctls */
case VHOST_ATTACH_VRING_WORKER:
case VHOST_GET_VRING_WORKER:
break;
default:
return -ENOIOCTLCMD;
}
ret = vhost_get_vq_from_user(dev, argp, &vq, &idx);
if (ret)
return ret;
switch (ioctl) {
case VHOST_ATTACH_VRING_WORKER:
if (copy_from_user(&ring_worker, argp, sizeof(ring_worker))) {
ret = -EFAULT;
break;
}
ret = vhost_vq_attach_worker(vq, &ring_worker);
break;
case VHOST_GET_VRING_WORKER:
worker = rcu_dereference_check(vq->worker,
lockdep_is_held(&dev->mutex));
if (!worker) {
ret = -EINVAL;
break;
}
ring_worker.index = idx;
ring_worker.worker_id = worker->id;
if (copy_to_user(argp, &ring_worker, sizeof(ring_worker)))
ret = -EFAULT;
break;
default:
ret = -ENOIOCTLCMD;
break;
}
return ret;
}
EXPORT_SYMBOL_GPL(vhost_worker_ioctl);
/* Caller should have device mutex */
long vhost_dev_set_owner(struct vhost_dev *dev)
{
struct vhost_worker *worker;
int err, i;
/* Is there an owner already? */
if (vhost_dev_has_owner(dev)) {
err = -EBUSY;
goto err_mm;
}
vhost_attach_mm(dev);
err = vhost_dev_alloc_iovecs(dev);
if (err)
goto err_iovecs;
if (dev->use_worker) {
/*
* This should be done last, because vsock can queue work
* before VHOST_SET_OWNER so it simplifies the failure path
* below since we don't have to worry about vsock queueing
* while we free the worker.
*/
worker = vhost_worker_create(dev);
if (!worker) {
err = -ENOMEM;
goto err_worker;
}
for (i = 0; i < dev->nvqs; i++)
__vhost_vq_attach_worker(dev->vqs[i], worker);
}
return 0;
err_worker:
vhost_dev_free_iovecs(dev);
err_iovecs:
vhost_detach_mm(dev);
err_mm:
return err;
}
EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
static struct vhost_iotlb *iotlb_alloc(void)
{
return vhost_iotlb_alloc(max_iotlb_entries,
VHOST_IOTLB_FLAG_RETIRE);
}
struct vhost_iotlb *vhost_dev_reset_owner_prepare(void)
{
return iotlb_alloc();
}
EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
/* Caller should have device mutex */
void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_iotlb *umem)
{
int i;
vhost_dev_cleanup(dev);
dev->umem = umem;
/* We don't need VQ locks below since vhost_dev_cleanup makes sure
* VQs aren't running.
*/
for (i = 0; i < dev->nvqs; ++i)
dev->vqs[i]->umem = umem;
}
EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
void vhost_dev_stop(struct vhost_dev *dev)
{
int i;
for (i = 0; i < dev->nvqs; ++i) {
if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick)
vhost_poll_stop(&dev->vqs[i]->poll);
}
vhost_dev_flush(dev);
}
EXPORT_SYMBOL_GPL(vhost_dev_stop);
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);
}
EXPORT_SYMBOL_GPL(vhost_clear_msg);
void vhost_dev_cleanup(struct vhost_dev *dev)
{
int i;
for (i = 0; i < dev->nvqs; ++i) {
if (dev->vqs[i]->error_ctx)
eventfd_ctx_put(dev->vqs[i]->error_ctx);
if (dev->vqs[i]->kick)
fput(dev->vqs[i]->kick);
if (dev->vqs[i]->call_ctx.ctx)
eventfd_ctx_put(dev->vqs[i]->call_ctx.ctx);
vhost_vq_reset(dev, dev->vqs[i]);
}
vhost_dev_free_iovecs(dev);
if (dev->log_ctx)
eventfd_ctx_put(dev->log_ctx);
dev->log_ctx = NULL;
/* No one will access memory at this point */
vhost_iotlb_free(dev->umem);
dev->umem = NULL;
vhost_iotlb_free(dev->iotlb);
dev->iotlb = NULL;
vhost_clear_msg(dev);
wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
vhost_workers_free(dev);
vhost_detach_mm(dev);
}
EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
{
u64 a = addr / VHOST_PAGE_SIZE / 8;
/* Make sure 64 bit math will not overflow. */
if (a > ULONG_MAX - (unsigned long)log_base ||
a + (unsigned long)log_base > ULONG_MAX)
return false;
return access_ok(log_base + a,
(sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
}
/* Make sure 64 bit math will not overflow. */
static bool vhost_overflow(u64 uaddr, u64 size)
{
if (uaddr > ULONG_MAX || size > ULONG_MAX)
return true;
if (!size)
return false;
return uaddr > ULONG_MAX - size + 1;
}
/* Caller should have vq mutex and device mutex. */
static bool vq_memory_access_ok(void __user *log_base, struct vhost_iotlb *umem,
int log_all)
{
struct vhost_iotlb_map *map;
if (!umem)
return false;
list_for_each_entry(map, &umem->list, link) {
unsigned long a = map->addr;
if (vhost_overflow(map->addr, map->size))
return false;
if (!access_ok((void __user *)a, map->size))
return false;
else if (log_all && !log_access_ok(log_base,
map->start,
map->size))
return false;
}
return true;
}
static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
u64 addr, unsigned int size,
int type)
{
const struct vhost_iotlb_map *map = vq->meta_iotlb[type];
if (!map)
return NULL;
return (void __user *)(uintptr_t)(map->addr + addr - map->start);
}
/* Can we switch to this memory table? */
/* Caller should have device mutex but not vq mutex */
static bool memory_access_ok(struct vhost_dev *d, struct vhost_iotlb *umem,
int log_all)
{
int i;
for (i = 0; i < d->nvqs; ++i) {
bool ok;
bool log;
mutex_lock(&d->vqs[i]->mutex);
log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
/* If ring is inactive, will check when it's enabled. */
if (d->vqs[i]->private_data)
ok = vq_memory_access_ok(d->vqs[i]->log_base,
umem, log);
else
ok = true;
mutex_unlock(&d->vqs[i]->mutex);
if (!ok)
return false;
}
return true;
}
static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
struct iovec iov[], int iov_size, int access);
static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
const void *from, unsigned size)
{
int ret;
if (!vq->iotlb)
return __copy_to_user(to, from, size);
else {
/* This function should be called after iotlb
* prefetch, which means we're sure that all vq
* could be access through iotlb. So -EAGAIN should
* not happen in this case.
*/
struct iov_iter t;
void __user *uaddr = vhost_vq_meta_fetch(vq,
(u64)(uintptr_t)to, size,
VHOST_ADDR_USED);
if (uaddr)
return __copy_to_user(uaddr, from, size);
ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
ARRAY_SIZE(vq->iotlb_iov),
VHOST_ACCESS_WO);
if (ret < 0)
goto out;
iov_iter_init(&t, ITER_DEST, 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, ITER_SOURCE, vq->iotlb_iov, ret, size);
ret = copy_from_iter(to, size, &f);
if (ret == size)
ret = 0;
}
out:
return ret;
}
static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
void __user *addr, unsigned int size,
int type)
{
int ret;
ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
ARRAY_SIZE(vq->iotlb_iov),
VHOST_ACCESS_RO);
if (ret < 0) {
vq_err(vq, "IOTLB translation failure: uaddr "
"%p size 0x%llx\n", addr,
(unsigned long long) size);
return NULL;
}
if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
vq_err(vq, "Non atomic userspace memory access: uaddr "
"%p size 0x%llx\n", addr,
(unsigned long long) size);
return NULL;
}
return vq->iotlb_iov[0].iov_base;
}
/* This function should be called after iotlb
* prefetch, which means we're sure that vq
* could be access through iotlb. So -EAGAIN should
* not happen in this case.
*/
static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
void __user *addr, unsigned int size,
int type)
{
void __user *uaddr = vhost_vq_meta_fetch(vq,
(u64)(uintptr_t)addr, size, type);
if (uaddr)
return uaddr;
return __vhost_get_user_slow(vq, addr, size, type);
}
#define vhost_put_user(vq, x, ptr) \
({ \
int ret; \
if (!vq->iotlb) { \
ret = __put_user(x, ptr); \
} else { \
__typeof__(ptr) to = \
(__typeof__(ptr)) __vhost_get_user(vq, ptr, \
sizeof(*ptr), VHOST_ADDR_USED); \
if (to != NULL) \
ret = __put_user(x, to); \
else \
ret = -EFAULT; \
} \
ret; \
})
static inline int vhost_put_avail_event(struct vhost_virtqueue *vq)
{
return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
vhost_avail_event(vq));
}
static inline int vhost_put_used(struct vhost_virtqueue *vq,
struct vring_used_elem *head, int idx,
int count)
{
return vhost_copy_to_user(vq, vq->used->ring + idx, head,
count * sizeof(*head));
}
static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
{
return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
&vq->used->flags);
}
static inline int vhost_put_used_idx(struct vhost_virtqueue *vq)
{
return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
&vq->used->idx);
}
#define vhost_get_user(vq, x, ptr, type) \
({ \
int ret; \
if (!vq->iotlb) { \
ret = __get_user(x, ptr); \
} else { \
__typeof__(ptr) from = \
(__typeof__(ptr)) __vhost_get_user(vq, ptr, \
sizeof(*ptr), \
type); \
if (from != NULL) \
ret = __get_user(x, from); \
else \
ret = -EFAULT; \
} \
ret; \
})
#define vhost_get_avail(vq, x, ptr) \
vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
#define vhost_get_used(vq, x, ptr) \
vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
static void vhost_dev_lock_vqs(struct vhost_dev *d)
{
int i = 0;
for (i = 0; i < d->nvqs; ++i)
mutex_lock_nested(&d->vqs[i]->mutex, i);
}
static void vhost_dev_unlock_vqs(struct vhost_dev *d)
{
int i = 0;
for (i = 0; i < d->nvqs; ++i)
mutex_unlock(&d->vqs[i]->mutex);
}
static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
__virtio16 *idx)
{
return vhost_get_avail(vq, *idx, &vq->avail->idx);
}
static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
__virtio16 *head, int idx)
{
return vhost_get_avail(vq, *head,
&vq->avail->ring[idx & (vq->num - 1)]);
}
static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
__virtio16 *flags)
{
return vhost_get_avail(vq, *flags, &vq->avail->flags);
}
static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
__virtio16 *event)
{
return vhost_get_avail(vq, *event, vhost_used_event(vq));
}
static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
__virtio16 *idx)
{
return vhost_get_used(vq, *idx, &vq->used->idx);
}
static inline int vhost_get_desc(struct vhost_virtqueue *vq,
struct vring_desc *desc, int idx)
{
return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc));
}
static void vhost_iotlb_notify_vq(struct vhost_dev *d,
struct vhost_iotlb_msg *msg)
{
struct vhost_msg_node *node, *n;
spin_lock(&d->iotlb_lock);
list_for_each_entry_safe(node, n, &d->pending_list, node) {
struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
if (msg->iova <= vq_msg->iova &&
msg->iova + msg->size - 1 >= vq_msg->iova &&
vq_msg->type == VHOST_IOTLB_MISS) {
vhost_poll_queue(&node->vq->poll);
list_del(&node->node);
kfree(node);
}
}
spin_unlock(&d->iotlb_lock);
}
static bool umem_access_ok(u64 uaddr, u64 size, int access)
{
unsigned long a = uaddr;
/* Make sure 64 bit math will not overflow. */
if (vhost_overflow(uaddr, size))
return false;
if ((access & VHOST_ACCESS_RO) &&
!access_ok((void __user *)a, size))
return false;
if ((access & VHOST_ACCESS_WO) &&
!access_ok((void __user *)a, size))
return false;
return true;
}
static int vhost_process_iotlb_msg(struct vhost_dev *dev, u32 asid,
struct vhost_iotlb_msg *msg)
{
int ret = 0;
if (asid != 0)
return -EINVAL;
mutex_lock(&dev->mutex);
vhost_dev_lock_vqs(dev);
switch (msg->type) {
case VHOST_IOTLB_UPDATE:
if (!dev->iotlb) {
ret = -EFAULT;
break;
}
if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
ret = -EFAULT;
break;
}
vhost_vq_meta_reset(dev);
if (vhost_iotlb_add_range(dev->iotlb, msg->iova,
msg->iova + msg->size - 1,
msg->uaddr, msg->perm)) {
ret = -ENOMEM;
break;
}
vhost_iotlb_notify_vq(dev, msg);
break;
case VHOST_IOTLB_INVALIDATE:
if (!dev->iotlb) {
ret = -EFAULT;
break;
}
vhost_vq_meta_reset(dev);
vhost_iotlb_del_range(dev->iotlb, msg->iova,
msg->iova + msg->size - 1);
break;
default:
ret = -EINVAL;
break;
}
vhost_dev_unlock_vqs(dev);
mutex_unlock(&dev->mutex);
return ret;
}
ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
struct iov_iter *from)
{
struct vhost_iotlb_msg msg;
size_t offset;
int type, ret;
u32 asid = 0;
ret = copy_from_iter(&type, sizeof(type), from);
if (ret != sizeof(type)) {
ret = -EINVAL;
goto done;
}
switch (type) {
case VHOST_IOTLB_MSG:
/* There maybe a hole after type for V1 message type,
* so skip it here.
*/
offset = offsetof(struct vhost_msg, iotlb) - sizeof(int);
break;
case VHOST_IOTLB_MSG_V2:
if (vhost_backend_has_feature(dev->vqs[0],
VHOST_BACKEND_F_IOTLB_ASID)) {
ret = copy_from_iter(&asid, sizeof(asid), from);
if (ret != sizeof(asid)) {
ret = -EINVAL;
goto done;
}
offset = 0;
} else
offset = sizeof(__u32);
break;
default:
ret = -EINVAL;
goto done;
}
iov_iter_advance(from, offset);
ret = copy_from_iter(&msg, sizeof(msg), from);
if (ret != sizeof(msg)) {
ret = -EINVAL;
goto done;
}
if ((msg.type == VHOST_IOTLB_UPDATE ||
msg.type == VHOST_IOTLB_INVALIDATE) &&
msg.size == 0) {
ret = -EINVAL;
goto done;
}
if (dev->msg_handler)
ret = dev->msg_handler(dev, asid, &msg);
else
ret = vhost_process_iotlb_msg(dev, asid, &msg);
if (ret) {
ret = -EFAULT;
goto done;
}
ret = (type == VHOST_IOTLB_MSG) ? sizeof(struct vhost_msg) :
sizeof(struct vhost_msg_v2);
done:
return ret;
}
EXPORT_SYMBOL(vhost_chr_write_iter);
__poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
poll_table *wait)
{
__poll_t mask = 0;
poll_wait(file, &dev->wait, wait);
if (!list_empty(&dev->read_list))
mask |= EPOLLIN | EPOLLRDNORM;
return mask;
}
EXPORT_SYMBOL(vhost_chr_poll);
ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
int noblock)
{
DEFINE_WAIT(wait);
struct vhost_msg_node *node;
ssize_t ret = 0;
unsigned size = sizeof(struct vhost_msg);
if (iov_iter_count(to) < size)
return 0;
while (1) {
if (!noblock)
prepare_to_wait(&dev->wait, &wait,
TASK_INTERRUPTIBLE);
node = vhost_dequeue_msg(dev, &dev->read_list);
if (node)
break;
if (noblock) {
ret = -EAGAIN;
break;
}
if (signal_pending(current)) {
ret = -ERESTARTSYS;
break;
}
if (!dev->iotlb) {
ret = -EBADFD;
break;
}
schedule();
}
if (!noblock)
finish_wait(&dev->wait, &wait);
if (node) {
struct vhost_iotlb_msg *msg;
void *start = &node->msg;
switch (node->msg.type) {
case VHOST_IOTLB_MSG:
size = sizeof(node->msg);
msg = &node->msg.iotlb;
break;
case VHOST_IOTLB_MSG_V2:
size = sizeof(node->msg_v2);
msg = &node->msg_v2.iotlb;
break;
default:
BUG();
break;
}
ret = copy_to_iter(start, size, to);
if (ret != size || msg->type != VHOST_IOTLB_MISS) {
kfree(node);
return ret;
}
vhost_enqueue_msg(dev, &dev->pending_list, node);
}
return ret;
}
EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
{
struct vhost_dev *dev = vq->dev;
struct vhost_msg_node *node;
struct vhost_iotlb_msg *msg;
bool v2 = vhost_backend_has_feature(vq, VHOST_BACKEND_F_IOTLB_MSG_V2);
node = vhost_new_msg(vq, v2 ? VHOST_IOTLB_MSG_V2 : VHOST_IOTLB_MSG);
if (!node)
return -ENOMEM;
if (v2) {
node->msg_v2.type = VHOST_IOTLB_MSG_V2;
msg = &node->msg_v2.iotlb;
} else {
msg = &node->msg.iotlb;
}
msg->type = VHOST_IOTLB_MISS;
msg->iova = iova;
msg->perm = access;
vhost_enqueue_msg(dev, &dev->read_list, node);
return 0;
}
static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
vring_desc_t __user *desc,
vring_avail_t __user *avail,
vring_used_t __user *used)
{
/* If an IOTLB device is present, the vring addresses are
* GIOVAs. Access validation occurs at prefetch time. */
if (vq->iotlb)
return true;
return access_ok(desc, vhost_get_desc_size(vq, num)) &&
access_ok(avail, vhost_get_avail_size(vq, num)) &&
access_ok(used, vhost_get_used_size(vq, num));
}
static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
const struct vhost_iotlb_map *map,
int type)
{
int access = (type == VHOST_ADDR_USED) ?
VHOST_ACCESS_WO : VHOST_ACCESS_RO;
if (likely(map->perm & access))
vq->meta_iotlb[type] = map;
}
static bool iotlb_access_ok(struct vhost_virtqueue *vq,
int access, u64 addr, u64 len, int type)
{
const struct vhost_iotlb_map *map;
struct vhost_iotlb *umem = vq->iotlb;
u64 s = 0, size, orig_addr = addr, last = addr + len - 1;
if (vhost_vq_meta_fetch(vq, addr, len, type))
return true;
while (len > s) {
map = vhost_iotlb_itree_first(umem, addr, last);
if (map == NULL || map->start > addr) {
vhost_iotlb_miss(vq, addr, access);
return false;
} else if (!(map->perm & access)) {
/* Report the possible access violation by
* request another translation from userspace.
*/
return false;
}
size = map->size - addr + map->start;
if (orig_addr == addr && size >= len)
vhost_vq_meta_update(vq, map, type);
s += size;
addr += size;
}
return true;
}
int vq_meta_prefetch(struct vhost_virtqueue *vq)
{
unsigned int num = vq->num;
if (!vq->iotlb)
return 1;
return iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->desc,
vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) &&
iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->avail,
vhost_get_avail_size(vq, num),
VHOST_ADDR_AVAIL) &&
iotlb_access_ok(vq, VHOST_MAP_WO, (u64)(uintptr_t)vq->used,
vhost_get_used_size(vq, num), VHOST_ADDR_USED);
}
EXPORT_SYMBOL_GPL(vq_meta_prefetch);
/* Can we log writes? */
/* Caller should have device mutex but not vq mutex */
bool vhost_log_access_ok(struct vhost_dev *dev)
{
return memory_access_ok(dev, dev->umem, 1);
}
EXPORT_SYMBOL_GPL(vhost_log_access_ok);
static bool vq_log_used_access_ok(struct vhost_virtqueue *vq,
void __user *log_base,
bool log_used,
u64 log_addr)
{
/* If an IOTLB device is present, log_addr is a GIOVA that
* will never be logged by log_used(). */
if (vq->iotlb)
return true;
return !log_used || log_access_ok(log_base, log_addr,
vhost_get_used_size(vq, vq->num));
}
/* Verify access for write logging. */
/* Caller should have vq mutex and device mutex */
static bool vq_log_access_ok(struct vhost_virtqueue *vq,
void __user *log_base)
{
return vq_memory_access_ok(log_base, vq->umem,
vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
vq_log_used_access_ok(vq, log_base, vq->log_used, vq->log_addr);
}
/* Can we start vq? */
/* Caller should have vq mutex and device mutex */
bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
{
if (!vq_log_access_ok(vq, vq->log_base))
return false;
return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
}
EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
{
struct vhost_memory mem, *newmem;
struct vhost_memory_region *region;
struct vhost_iotlb *newumem, *oldumem;
unsigned long size = offsetof(struct vhost_memory, regions);
int i;
if (copy_from_user(&mem, m, size))
return -EFAULT;
if (mem.padding)
return -EOPNOTSUPP;
if (mem.nregions > max_mem_regions)
return -E2BIG;
newmem = kvzalloc(struct_size(newmem, regions, mem.nregions),
GFP_KERNEL);
if (!newmem)
return -ENOMEM;
memcpy(newmem, &mem, size);
if (copy_from_user(newmem->regions, m->regions,
flex_array_size(newmem, regions, mem.nregions))) {
kvfree(newmem);
return -EFAULT;
}
newumem = iotlb_alloc();
if (!newumem) {
kvfree(newmem);
return -ENOMEM;
}
for (region = newmem->regions;
region < newmem->regions + mem.nregions;
region++) {
if (vhost_iotlb_add_range(newumem,
region->guest_phys_addr,
region->guest_phys_addr +
region->memory_size - 1,
region->userspace_addr,
VHOST_MAP_RW))
goto err;
}
if (!memory_access_ok(d, newumem, 0))
goto err;
oldumem = d->umem;
d->umem = newumem;
/* All memory accesses are done under some VQ mutex. */
for (i = 0; i < d->nvqs; ++i) {
mutex_lock(&d->vqs[i]->mutex);
d->vqs[i]->umem = newumem;
mutex_unlock(&d->vqs[i]->mutex);
}
kvfree(newmem);
vhost_iotlb_free(oldumem);
return 0;
err:
vhost_iotlb_free(newumem);
kvfree(newmem);
return -EFAULT;
}
static long vhost_vring_set_num(struct vhost_dev *d,
struct vhost_virtqueue *vq,
void __user *argp)
{
struct vhost_vring_state s;
/* Resizing ring with an active backend?
* You don't want to do that. */
if (vq->private_data)
return -EBUSY;
if (copy_from_user(&s, argp, sizeof s))
return -EFAULT;
if (!s.num || s.num > 0xffff || (s.num & (s.num - 1)))
return -EINVAL;
vq->num = s.num;
return 0;
}
static long vhost_vring_set_addr(struct vhost_dev *d,
struct vhost_virtqueue *vq,
void __user *argp)
{
struct vhost_vring_addr a;
if (copy_from_user(&a, argp, sizeof a))
return -EFAULT;
if (a.flags & ~(0x1 << VHOST_VRING_F_LOG))
return -EOPNOTSUPP;
/* For 32bit, verify that the top 32bits of the user
data are set to zero. */
if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
(u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
(u64)(unsigned long)a.avail_user_addr != a.avail_user_addr)
return -EFAULT;
/* Make sure it's safe to cast pointers to vring types. */
BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
(a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
(a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1)))
return -EINVAL;
/* We only verify access here if backend is configured.
* If it is not, we don't as size might not have been setup.
* We will verify when backend is configured. */
if (vq->private_data) {
if (!vq_access_ok(vq, vq->num,
(void __user *)(unsigned long)a.desc_user_addr,
(void __user *)(unsigned long)a.avail_user_addr,
(void __user *)(unsigned long)a.used_user_addr))
return -EINVAL;
/* Also validate log access for used ring if enabled. */
if (!vq_log_used_access_ok(vq, vq->log_base,
a.flags & (0x1 << VHOST_VRING_F_LOG),
a.log_guest_addr))
return -EINVAL;
}
vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
vq->log_addr = a.log_guest_addr;
vq->used = (void __user *)(unsigned long)a.used_user_addr;
return 0;
}
static long vhost_vring_set_num_addr(struct vhost_dev *d,
struct vhost_virtqueue *vq,
unsigned int ioctl,
void __user *argp)
{
long r;
mutex_lock(&vq->mutex);
switch (ioctl) {
case VHOST_SET_VRING_NUM:
r = vhost_vring_set_num(d, vq, argp);
break;
case VHOST_SET_VRING_ADDR:
r = vhost_vring_set_addr(d, vq, argp);
break;
default:
BUG();
}
mutex_unlock(&vq->mutex);
return r;
}
long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
{
struct file *eventfp, *filep = NULL;
bool pollstart = false, pollstop = false;
struct eventfd_ctx *ctx = NULL;
struct vhost_virtqueue *vq;
struct vhost_vring_state s;
struct vhost_vring_file f;
u32 idx;
long r;
r = vhost_get_vq_from_user(d, argp, &vq, &idx);
if (r < 0)
return r;
if (ioctl == VHOST_SET_VRING_NUM ||
ioctl == VHOST_SET_VRING_ADDR) {
return vhost_vring_set_num_addr(d, vq, ioctl, argp);
}
mutex_lock(&vq->mutex);
switch (ioctl) {
case VHOST_SET_VRING_BASE:
/* Moving base with an active backend?
* You don't want to do that. */
if (vq->private_data) {
r = -EBUSY;
break;
}
if (copy_from_user(&s, argp, sizeof s)) {
r = -EFAULT;
break;
}
if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
vq->last_avail_idx = s.num & 0xffff;
vq->last_used_idx = (s.num >> 16) & 0xffff;
} else {
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;
if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
s.num = (u32)vq->last_avail_idx | ((u32)vq->last_used_idx << 16);
else
s.num = vq->last_avail_idx;
if (copy_to_user(argp, &s, sizeof s))
r = -EFAULT;
break;
case VHOST_SET_VRING_KICK:
if (copy_from_user(&f, argp, sizeof f)) {
r = -EFAULT;
break;
}
eventfp = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_fget(f.fd);
if (IS_ERR(eventfp)) {
r = PTR_ERR(eventfp);
break;
}
if (eventfp != vq->kick) {
pollstop = (filep = vq->kick) != NULL;
pollstart = (vq->kick = eventfp) != NULL;
} else
filep = eventfp;
break;
case VHOST_SET_VRING_CALL:
if (copy_from_user(&f, argp, sizeof f)) {
r = -EFAULT;
break;
}
ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd);
if (IS_ERR(ctx)) {
r = PTR_ERR(ctx);
break;
}
swap(ctx, vq->call_ctx.ctx);
break;
case VHOST_SET_VRING_ERR:
if (copy_from_user(&f, argp, sizeof f)) {
r = -EFAULT;
break;
}
ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd);
if (IS_ERR(ctx)) {
r = PTR_ERR(ctx);
break;
}
swap(ctx, vq->error_ctx);
break;
case VHOST_SET_VRING_ENDIAN:
r = vhost_set_vring_endian(vq, argp);
break;
case VHOST_GET_VRING_ENDIAN:
r = vhost_get_vring_endian(vq, idx, argp);
break;
case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
if (copy_from_user(&s, argp, sizeof(s))) {
r = -EFAULT;
break;
}
vq->busyloop_timeout = s.num;
break;
case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
s.index = idx;
s.num = vq->busyloop_timeout;
if (copy_to_user(argp, &s, sizeof(s)))
r = -EFAULT;
break;
default:
r = -ENOIOCTLCMD;
}
if (pollstop && vq->handle_kick)
vhost_poll_stop(&vq->poll);
if (!IS_ERR_OR_NULL(ctx))
eventfd_ctx_put(ctx);
if (filep)
fput(filep);
if (pollstart && vq->handle_kick)
r = vhost_poll_start(&vq->poll, vq->kick);
mutex_unlock(&vq->mutex);
if (pollstop && vq->handle_kick)
vhost_dev_flush(vq->poll.dev);
return r;
}
EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
int vhost_init_device_iotlb(struct vhost_dev *d)
{
struct vhost_iotlb *niotlb, *oiotlb;
int i;
niotlb = iotlb_alloc();
if (!niotlb)
return -ENOMEM;
oiotlb = d->iotlb;
d->iotlb = niotlb;
for (i = 0; i < d->nvqs; ++i) {
struct vhost_virtqueue *vq = d->vqs[i];
mutex_lock(&vq->mutex);
vq->iotlb = niotlb;
__vhost_vq_meta_reset(vq);
mutex_unlock(&vq->mutex);
}
vhost_iotlb_free(oiotlb);
return 0;
}
EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
/* Caller must have device mutex */
long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
{
struct eventfd_ctx *ctx;
u64 p;
long r;
int i, fd;
/* If you are not the owner, you can become one */
if (ioctl == VHOST_SET_OWNER) {
r = vhost_dev_set_owner(d);
goto done;
}
/* You must be the owner to do anything else */
r = vhost_dev_check_owner(d);
if (r)
goto done;
switch (ioctl) {
case VHOST_SET_MEM_TABLE:
r = vhost_set_memory(d, argp);
break;
case VHOST_SET_LOG_BASE:
if (copy_from_user(&p, argp, sizeof p)) {
r = -EFAULT;
break;
}
if ((u64)(unsigned long)p != p) {
r = -EFAULT;
break;
}
for (i = 0; i < d->nvqs; ++i) {
struct vhost_virtqueue *vq;
void __user *base = (void __user *)(unsigned long)p;
vq = d->vqs[i];
mutex_lock(&vq->mutex);
/* If ring is inactive, will check when it's enabled. */
if (vq->private_data && !vq_log_access_ok(vq, base))
r = -EFAULT;
else
vq->log_base = base;
mutex_unlock(&vq->mutex);
}
break;
case VHOST_SET_LOG_FD:
r = get_user(fd, (int __user *)argp);
if (r < 0)
break;
ctx = fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(fd);
if (IS_ERR(ctx)) {
r = PTR_ERR(ctx);
break;
}
swap(ctx, d->log_ctx);
for (i = 0; i < d->nvqs; ++i) {
mutex_lock(&d->vqs[i]->mutex);
d->vqs[i]->log_ctx = d->log_ctx;
mutex_unlock(&d->vqs[i]->mutex);
}
if (ctx)
eventfd_ctx_put(ctx);
break;
default:
r = -ENOIOCTLCMD;
break;
}
done:
return r;
}
EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
/* TODO: This is really inefficient. We need something like get_user()
* (instruction directly accesses the data, with an exception table entry
* returning -EFAULT). See Documentation/arch/x86/exception-tables.rst.
*/
static int set_bit_to_user(int nr, void __user *addr)
{
unsigned long log = (unsigned long)addr;
struct page *page;
void *base;
int bit = nr + (log % PAGE_SIZE) * 8;
int r;
r = pin_user_pages_fast(log, 1, FOLL_WRITE, &page);
if (r < 0)
return r;
BUG_ON(r != 1);
base = kmap_atomic(page);
set_bit(bit, base);
kunmap_atomic(base);
unpin_user_pages_dirty_lock(&page, 1, true);
return 0;
}
static int log_write(void __user *log_base,
u64 write_address, u64 write_length)
{
u64 write_page = write_address / VHOST_PAGE_SIZE;
int r;
if (!write_length)
return 0;
write_length += write_address % VHOST_PAGE_SIZE;
for (;;) {
u64 base = (u64)(unsigned long)log_base;
u64 log = base + write_page / 8;
int bit = write_page % 8;
if ((u64)(unsigned long)log != log)
return -EFAULT;
r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
if (r < 0)
return r;
if (write_length <= VHOST_PAGE_SIZE)
break;
write_length -= VHOST_PAGE_SIZE;
write_page += 1;
}
return r;
}
static int log_write_hva(struct vhost_virtqueue *vq, u64 hva, u64 len)
{
struct vhost_iotlb *umem = vq->umem;
struct vhost_iotlb_map *u;
u64 start, end, l, min;
int r;
bool hit = false;
while (len) {
min = len;
/* More than one GPAs can be mapped into a single HVA. So
* iterate all possible umems here to be safe.
*/
list_for_each_entry(u, &umem->list, link) {
if (u->addr > hva - 1 + len ||
u->addr - 1 + u->size < hva)
continue;
start = max(u->addr, hva);
end = min(u->addr - 1 + u->size, hva - 1 + len);
l = end - start + 1;
r = log_write(vq->log_base,
u->start + start - u->addr,
l);
if (r < 0)
return r;
hit = true;
min = min(l, min);
}
if (!hit)
return -EFAULT;
len -= min;
hva += min;
}
return 0;
}
static int log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len)
{
struct iovec *iov = vq->log_iov;
int i, ret;
if (!vq->iotlb)
return log_write(vq->log_base, vq->log_addr + used_offset, len);
ret = translate_desc(vq, (uintptr_t)vq->used + used_offset,
len, iov, 64, VHOST_ACCESS_WO);
if (ret < 0)
return ret;
for (i = 0; i < ret; i++) {
ret = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
iov[i].iov_len);
if (ret)
return ret;
}
return 0;
}
int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
unsigned int log_num, u64 len, struct iovec *iov, int count)
{
int i, r;
/* Make sure data written is seen before log. */
smp_wmb();
if (vq->iotlb) {
for (i = 0; i < count; i++) {
r = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
iov[i].iov_len);
if (r < 0)
return r;
}
return 0;
}
for (i = 0; i < log_num; ++i) {
u64 l = min(log[i].len, len);
r = log_write(vq->log_base, log[i].addr, l);
if (r < 0)
return r;
len -= l;
if (!len) {
if (vq->log_ctx)
eventfd_signal(vq->log_ctx, 1);
return 0;
}
}
/* Length written exceeds what we have stored. This is a bug. */
BUG();
return 0;
}
EXPORT_SYMBOL_GPL(vhost_log_write);
static int vhost_update_used_flags(struct vhost_virtqueue *vq)
{
void __user *used;
if (vhost_put_used_flags(vq))
return -EFAULT;
if (unlikely(vq->log_used)) {
/* Make sure the flag is seen before log. */
smp_wmb();
/* Log used flag write. */
used = &vq->used->flags;
log_used(vq, (used - (void __user *)vq->used),
sizeof vq->used->flags);
if (vq->log_ctx)
eventfd_signal(vq->log_ctx, 1);
}
return 0;
}
static int vhost_update_avail_event(struct vhost_virtqueue *vq)
{
if (vhost_put_avail_event(vq))
return -EFAULT;
if (unlikely(vq->log_used)) {
void __user *used;
/* Make sure the event is seen before log. */
smp_wmb();
/* Log avail event write */
used = vhost_avail_event(vq);
log_used(vq, (used - (void __user *)vq->used),
sizeof *vhost_avail_event(vq));
if (vq->log_ctx)
eventfd_signal(vq->log_ctx, 1);
}
return 0;
}
int vhost_vq_init_access(struct vhost_virtqueue *vq)
{
__virtio16 last_used_idx;
int r;
bool is_le = vq->is_le;
if (!vq->private_data)
return 0;
vhost_init_is_le(vq);
r = vhost_update_used_flags(vq);
if (r)
goto err;
vq->signalled_used_valid = false;
if (!vq->iotlb &&
!access_ok(&vq->used->idx, sizeof vq->used->idx)) {
r = -EFAULT;
goto err;
}
r = vhost_get_used_idx(vq, &last_used_idx);
if (r) {
vq_err(vq, "Can't access used idx at %p\n",
&vq->used->idx);
goto err;
}
vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
return 0;
err:
vq->is_le = is_le;
return r;
}
EXPORT_SYMBOL_GPL(vhost_vq_init_access);
static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
struct iovec iov[], int iov_size, int access)
{
const struct vhost_iotlb_map *map;
struct vhost_dev *dev = vq->dev;
struct vhost_iotlb *umem = dev->iotlb ? dev->iotlb : dev->umem;
struct iovec *_iov;
u64 s = 0, last = addr + len - 1;
int ret = 0;
while ((u64)len > s) {
u64 size;
if (unlikely(ret >= iov_size)) {
ret = -ENOBUFS;
break;
}
map = vhost_iotlb_itree_first(umem, addr, last);
if (map == NULL || map->start > addr) {
if (umem != dev->iotlb) {
ret = -EFAULT;
break;
}
ret = -EAGAIN;
break;
} else if (!(map->perm & access)) {
ret = -EPERM;
break;
}
_iov = iov + ret;
size = map->size - addr + map->start;
_iov->iov_len = min((u64)len - s, size);
_iov->iov_base = (void __user *)(unsigned long)
(map->addr + addr - map->start);
s += size;
addr += size;
++ret;
}
if (ret == -EAGAIN)
vhost_iotlb_miss(vq, addr, access);
return ret;
}
/* Each buffer in the virtqueues is actually a chain of descriptors. This
* function returns the next descriptor in the chain,
* or -1U if we're at the end. */
static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
{
unsigned int next;
/* If this descriptor says it doesn't chain, we're done. */
if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
return -1U;
/* Check they're not leading us off end of descriptors. */
next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
return next;
}
static int get_indirect(struct vhost_virtqueue *vq,
struct iovec iov[], unsigned int iov_size,
unsigned int *out_num, unsigned int *in_num,
struct vhost_log *log, unsigned int *log_num,
struct vring_desc *indirect)
{
struct vring_desc desc;
unsigned int i = 0, count, found = 0;
u32 len = vhost32_to_cpu(vq, indirect->len);
struct iov_iter from;
int ret, access;
/* Sanity check */
if (unlikely(len % sizeof desc)) {
vq_err(vq, "Invalid length in indirect descriptor: "
"len 0x%llx not multiple of 0x%zx\n",
(unsigned long long)len,
sizeof desc);
return -EINVAL;
}
ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
UIO_MAXIOV, VHOST_ACCESS_RO);
if (unlikely(ret < 0)) {
if (ret != -EAGAIN)
vq_err(vq, "Translation failure %d in indirect.\n", ret);
return ret;
}
iov_iter_init(&from, ITER_SOURCE, vq->indirect, ret, len);
count = len / sizeof desc;
/* Buffers are chained via a 16 bit next field, so
* we can have at most 2^16 of these. */
if (unlikely(count > USHRT_MAX + 1)) {
vq_err(vq, "Indirect buffer length too big: %d\n",
indirect->len);
return -E2BIG;
}
do {
unsigned iov_count = *in_num + *out_num;
if (unlikely(++found > count)) {
vq_err(vq, "Loop detected: last one at %u "
"indirect size %u\n",
i, count);
return -EINVAL;
}
if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
return -EINVAL;
}
if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
return -EINVAL;
}
if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
access = VHOST_ACCESS_WO;
else
access = VHOST_ACCESS_RO;
ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
vhost32_to_cpu(vq, desc.len), iov + iov_count,
iov_size - iov_count, access);
if (unlikely(ret < 0)) {
if (ret != -EAGAIN)
vq_err(vq, "Translation failure %d indirect idx %d\n",
ret, i);
return ret;
}
/* If this is an input descriptor, increment that count. */
if (access == VHOST_ACCESS_WO) {
*in_num += ret;
if (unlikely(log && ret)) {
log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
log[*log_num].len = vhost32_to_cpu(vq, desc.len);
++*log_num;
}
} else {
/* If it's an output descriptor, they're all supposed
* to come before any input descriptors. */
if (unlikely(*in_num)) {
vq_err(vq, "Indirect descriptor "
"has out after in: idx %d\n", i);
return -EINVAL;
}
*out_num += ret;
}
} while ((i = next_desc(vq, &desc)) != -1);
return 0;
}
/* This looks in the virtqueue and for the first available buffer, and converts
* it to an iovec for convenient access. Since descriptors consist of some
* number of output then some number of input descriptors, it's actually two
* iovecs, but we pack them into one and note how many of each there were.
*
* This function returns the descriptor number found, or vq->num (which is
* never a valid descriptor number) if none was found. A negative code is
* returned on error. */
int vhost_get_vq_desc(struct vhost_virtqueue *vq,
struct iovec iov[], unsigned int iov_size,
unsigned int *out_num, unsigned int *in_num,
struct vhost_log *log, unsigned int *log_num)
{
struct vring_desc desc;
unsigned int i, head, found = 0;
u16 last_avail_idx;
__virtio16 avail_idx;
__virtio16 ring_head;
int ret, access;
/* Check it isn't doing very strange things with descriptor numbers. */
last_avail_idx = vq->last_avail_idx;
if (vq->avail_idx == vq->last_avail_idx) {
if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) {
vq_err(vq, "Failed to access avail idx at %p\n",
&vq->avail->idx);
return -EFAULT;
}
vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
vq_err(vq, "Guest moved used index from %u to %u",
last_avail_idx, vq->avail_idx);
return -EFAULT;
}
/* If there's nothing new since last we looked, return
* invalid.
*/
if (vq->avail_idx == last_avail_idx)
return vq->num;
/* Only get avail ring entries after they have been
* exposed by guest.
*/
smp_rmb();
}
/* Grab the next descriptor number they're advertising, and increment
* the index we've seen. */
if (unlikely(vhost_get_avail_head(vq, &ring_head, last_avail_idx))) {
vq_err(vq, "Failed to read head: idx %d address %p\n",
last_avail_idx,
&vq->avail->ring[last_avail_idx % vq->num]);
return -EFAULT;
}
head = vhost16_to_cpu(vq, ring_head);
/* If their number is silly, that's an error. */
if (unlikely(head >= vq->num)) {
vq_err(vq, "Guest says index %u > %u is available",
head, vq->num);
return -EINVAL;
}
/* When we start there are none of either input nor output. */
*out_num = *in_num = 0;
if (unlikely(log))
*log_num = 0;
i = head;
do {
unsigned iov_count = *in_num + *out_num;
if (unlikely(i >= vq->num)) {
vq_err(vq, "Desc index is %u > %u, head = %u",
i, vq->num, head);
return -EINVAL;
}
if (unlikely(++found > vq->num)) {
vq_err(vq, "Loop detected: last one at %u "
"vq size %u head %u\n",
i, vq->num, head);
return -EINVAL;
}
ret = vhost_get_desc(vq, &desc, i);
if (unlikely(ret)) {
vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
i, vq->desc + i);
return -EFAULT;
}
if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
ret = get_indirect(vq, iov, iov_size,
out_num, in_num,
log, log_num, &desc);
if (unlikely(ret < 0)) {
if (ret != -EAGAIN)
vq_err(vq, "Failure detected "
"in indirect descriptor at idx %d\n", i);
return ret;
}
continue;
}
if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
access = VHOST_ACCESS_WO;
else
access = VHOST_ACCESS_RO;
ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
vhost32_to_cpu(vq, desc.len), iov + iov_count,
iov_size - iov_count, access);
if (unlikely(ret < 0)) {
if (ret != -EAGAIN)
vq_err(vq, "Translation failure %d descriptor idx %d\n",
ret, i);
return ret;
}
if (access == VHOST_ACCESS_WO) {
/* If this is an input descriptor,
* increment that count. */
*in_num += ret;
if (unlikely(log && ret)) {
log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
log[*log_num].len = vhost32_to_cpu(vq, desc.len);
++*log_num;
}
} else {
/* If it's an output descriptor, they're all supposed
* to come before any input descriptors. */
if (unlikely(*in_num)) {
vq_err(vq, "Descriptor has out after in: "
"idx %d\n", i);
return -EINVAL;
}
*out_num += ret;
}
} while ((i = next_desc(vq, &desc)) != -1);
/* On success, increment avail index. */
vq->last_avail_idx++;
/* Assume notifications from guest are disabled at this point,
* if they aren't we would need to update avail_event index. */
BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
return head;
}
EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
/* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
{
vq->last_avail_idx -= n;
}
EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
/* After we've used one of their buffers, we tell them about it. We'll then
* want to notify the guest, using eventfd. */
int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
{
struct vring_used_elem heads = {
cpu_to_vhost32(vq, head),
cpu_to_vhost32(vq, len)
};
return vhost_add_used_n(vq, &heads, 1);
}
EXPORT_SYMBOL_GPL(vhost_add_used);
static int __vhost_add_used_n(struct vhost_virtqueue *vq,
struct vring_used_elem *heads,
unsigned count)
{
vring_used_elem_t __user *used;
u16 old, new;
int start;
start = vq->last_used_idx & (vq->num - 1);
used = vq->used->ring + start;
if (vhost_put_used(vq, heads, start, count)) {
vq_err(vq, "Failed to write used");
return -EFAULT;
}
if (unlikely(vq->log_used)) {
/* Make sure data is seen before log. */
smp_wmb();
/* Log used ring entry write. */
log_used(vq, ((void __user *)used - (void __user *)vq->used),
count * sizeof *used);
}
old = vq->last_used_idx;
new = (vq->last_used_idx += count);
/* If the driver never bothers to signal in a very long while,
* used index might wrap around. If that happens, invalidate
* signalled_used index we stored. TODO: make sure driver
* signals at least once in 2^16 and remove this. */
if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
vq->signalled_used_valid = false;
return 0;
}
/* After we've used one of their buffers, we tell them about it. We'll then
* want to notify the guest, using eventfd. */
int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
unsigned count)
{
int start, n, r;
start = vq->last_used_idx & (vq->num - 1);
n = vq->num - start;
if (n < count) {
r = __vhost_add_used_n(vq, heads, n);
if (r < 0)
return r;
heads += n;
count -= n;
}
r = __vhost_add_used_n(vq, heads, count);
/* Make sure buffer is written before we update index. */
smp_wmb();
if (vhost_put_used_idx(vq)) {
vq_err(vq, "Failed to increment used idx");
return -EFAULT;
}
if (unlikely(vq->log_used)) {
/* Make sure used idx is seen before log. */
smp_wmb();
/* Log used index update. */
log_used(vq, offsetof(struct vring_used, idx),
sizeof vq->used->idx);
if (vq->log_ctx)
eventfd_signal(vq->log_ctx, 1);
}
return r;
}
EXPORT_SYMBOL_GPL(vhost_add_used_n);
static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
{
__u16 old, new;
__virtio16 event;
bool v;
/* Flush out used index updates. This is paired
* with the barrier that the Guest executes when enabling
* interrupts. */
smp_mb();
if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
unlikely(vq->avail_idx == vq->last_avail_idx))
return true;
if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
__virtio16 flags;
if (vhost_get_avail_flags(vq, &flags)) {
vq_err(vq, "Failed to get flags");
return true;
}
return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
}
old = vq->signalled_used;
v = vq->signalled_used_valid;
new = vq->signalled_used = vq->last_used_idx;
vq->signalled_used_valid = true;
if (unlikely(!v))
return true;
if (vhost_get_used_event(vq, &event)) {
vq_err(vq, "Failed to get used event idx");
return true;
}
return vring_need_event(vhost16_to_cpu(vq, event), new, old);
}
/* This actually signals the guest, using eventfd. */
void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
{
/* Signal the Guest tell them we used something up. */
if (vq->call_ctx.ctx && vhost_notify(dev, vq))
eventfd_signal(vq->call_ctx.ctx, 1);
}
EXPORT_SYMBOL_GPL(vhost_signal);
/* And here's the combo meal deal. Supersize me! */
void vhost_add_used_and_signal(struct vhost_dev *dev,
struct vhost_virtqueue *vq,
unsigned int head, int len)
{
vhost_add_used(vq, head, len);
vhost_signal(dev, vq);
}
EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
/* multi-buffer version of vhost_add_used_and_signal */
void vhost_add_used_and_signal_n(struct vhost_dev *dev,
struct vhost_virtqueue *vq,
struct vring_used_elem *heads, unsigned count)
{
vhost_add_used_n(vq, heads, count);
vhost_signal(dev, vq);
}
EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
/* return true if we're sure that avaiable ring is empty */
bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
{
__virtio16 avail_idx;
int r;
if (vq->avail_idx != vq->last_avail_idx)
return false;
r = vhost_get_avail_idx(vq, &avail_idx);
if (unlikely(r))
return false;
vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
return vq->avail_idx == vq->last_avail_idx;
}
EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
/* OK, now we need to know about added descriptors. */
bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
{
__virtio16 avail_idx;
int r;
if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
return false;
vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
r = vhost_update_used_flags(vq);
if (r) {
vq_err(vq, "Failed to enable notification at %p: %d\n",
&vq->used->flags, r);
return false;
}
} else {
r = vhost_update_avail_event(vq);
if (r) {
vq_err(vq, "Failed to update avail event index at %p: %d\n",
vhost_avail_event(vq), r);
return false;
}
}
/* They could have slipped one in as we were doing that: make
* sure it's written, then check again. */
smp_mb();
r = vhost_get_avail_idx(vq, &avail_idx);
if (r) {
vq_err(vq, "Failed to check avail idx at %p: %d\n",
&vq->avail->idx, r);
return false;
}
vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
return vq->avail_idx != vq->last_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 disable 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)
{
/* Make sure all padding within the structure is initialized. */
struct vhost_msg_node *node = kzalloc(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, EPOLLIN | EPOLLRDNORM);
}
EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
struct list_head *head)
{
struct vhost_msg_node *node = NULL;
spin_lock(&dev->iotlb_lock);
if (!list_empty(head)) {
node = list_first_entry(head, struct vhost_msg_node,
node);
list_del(&node->node);
}
spin_unlock(&dev->iotlb_lock);
return node;
}
EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
void vhost_set_backend_features(struct vhost_dev *dev, u64 features)
{
struct vhost_virtqueue *vq;
int i;
mutex_lock(&dev->mutex);
for (i = 0; i < dev->nvqs; ++i) {
vq = dev->vqs[i];
mutex_lock(&vq->mutex);
vq->acked_backend_features = features;
mutex_unlock(&vq->mutex);
}
mutex_unlock(&dev->mutex);
}
EXPORT_SYMBOL_GPL(vhost_set_backend_features);
static int __init vhost_init(void)
{
return 0;
}
static void __exit vhost_exit(void)
{
}
module_init(vhost_init);
module_exit(vhost_exit);
MODULE_VERSION("0.0.1");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Michael S. Tsirkin");
MODULE_DESCRIPTION("Host kernel accelerator for virtio");
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