Commit e12ca23d authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus

* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
  virtio_net: delay TX callbacks
  virtio: add api for delayed callbacks
  virtio_test: support event index
  vhost: support event index
  virtio_ring: support event idx feature
  virtio ring: inline function to check for events
  virtio: event index interface
  virtio: add full three-clause BSD text to headers.
  virtio balloon: kill tell-host-first logic
  virtio console: don't manually set or finalize VIRTIO_CONSOLE_F_MULTIPORT.
  drivers, block: virtio_blk: Replace cryptic number with the macro
  virtio_blk: allow re-reading config space at runtime
  lguest: remove support for VIRTIO_F_NOTIFY_ON_EMPTY.
  lguest: fix up compilation after move
  lguest: fix timer interrupt setup
parents 850761b2 7a66f784
# This creates the demonstration utility "lguest" which runs a Linux guest.
# Missing headers? Add "-I../../include -I../../arch/x86/include"
# Missing headers? Add "-I../../../include -I../../../arch/x86/include"
CFLAGS:=-m32 -Wall -Wmissing-declarations -Wmissing-prototypes -O3 -U_FORTIFY_SOURCE
all: lguest
......
......@@ -49,7 +49,7 @@
#include <linux/virtio_rng.h>
#include <linux/virtio_ring.h>
#include <asm/bootparam.h>
#include "../../include/linux/lguest_launcher.h"
#include "../../../include/linux/lguest_launcher.h"
/*L:110
* We can ignore the 42 include files we need for this program, but I do want
* to draw attention to the use of kernel-style types.
......@@ -135,9 +135,6 @@ struct device {
/* Is it operational */
bool running;
/* Does Guest want an intrrupt on empty? */
bool irq_on_empty;
/* Device-specific data. */
void *priv;
};
......@@ -637,10 +634,7 @@ static void trigger_irq(struct virtqueue *vq)
/* If they don't want an interrupt, don't send one... */
if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) {
/* ... unless they've asked us to force one on empty. */
if (!vq->dev->irq_on_empty
|| lg_last_avail(vq) != vq->vring.avail->idx)
return;
return;
}
/* Send the Guest an interrupt tell them we used something up. */
......@@ -1057,15 +1051,6 @@ static void create_thread(struct virtqueue *vq)
close(vq->eventfd);
}
static bool accepted_feature(struct device *dev, unsigned int bit)
{
const u8 *features = get_feature_bits(dev) + dev->feature_len;
if (dev->feature_len < bit / CHAR_BIT)
return false;
return features[bit / CHAR_BIT] & (1 << (bit % CHAR_BIT));
}
static void start_device(struct device *dev)
{
unsigned int i;
......@@ -1079,8 +1064,6 @@ static void start_device(struct device *dev)
verbose(" %02x", get_feature_bits(dev)
[dev->feature_len+i]);
dev->irq_on_empty = accepted_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY);
for (vq = dev->vq; vq; vq = vq->next) {
if (vq->service)
create_thread(vq);
......@@ -1564,7 +1547,6 @@ static void setup_tun_net(char *arg)
/* Set up the tun device. */
configure_device(ipfd, tapif, ip);
add_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY);
/* Expect Guest to handle everything except UFO */
add_feature(dev, VIRTIO_NET_F_CSUM);
add_feature(dev, VIRTIO_NET_F_GUEST_CSUM);
......
......@@ -993,6 +993,7 @@ static void lguest_time_irq(unsigned int irq, struct irq_desc *desc)
static void lguest_time_init(void)
{
/* Set up the timer interrupt (0) to go to our simple timer routine */
lguest_setup_irq(0);
irq_set_handler(0, lguest_time_irq);
clocksource_register_hz(&lguest_clock, NSEC_PER_SEC);
......
......@@ -6,10 +6,13 @@
#include <linux/virtio.h>
#include <linux/virtio_blk.h>
#include <linux/scatterlist.h>
#include <linux/string_helpers.h>
#include <scsi/scsi_cmnd.h>
#define PART_BITS 4
static int major, index;
struct workqueue_struct *virtblk_wq;
struct virtio_blk
{
......@@ -26,6 +29,9 @@ struct virtio_blk
mempool_t *pool;
/* Process context for config space updates */
struct work_struct config_work;
/* What host tells us, plus 2 for header & tailer. */
unsigned int sg_elems;
......@@ -141,7 +147,7 @@ static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
num = blk_rq_map_sg(q, vbr->req, vblk->sg + out);
if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) {
sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, 96);
sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, SCSI_SENSE_BUFFERSIZE);
sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr,
sizeof(vbr->in_hdr));
}
......@@ -291,6 +297,46 @@ static ssize_t virtblk_serial_show(struct device *dev,
}
DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
static void virtblk_config_changed_work(struct work_struct *work)
{
struct virtio_blk *vblk =
container_of(work, struct virtio_blk, config_work);
struct virtio_device *vdev = vblk->vdev;
struct request_queue *q = vblk->disk->queue;
char cap_str_2[10], cap_str_10[10];
u64 capacity, size;
/* Host must always specify the capacity. */
vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
&capacity, sizeof(capacity));
/* If capacity is too big, truncate with warning. */
if ((sector_t)capacity != capacity) {
dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
(unsigned long long)capacity);
capacity = (sector_t)-1;
}
size = capacity * queue_logical_block_size(q);
string_get_size(size, STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
string_get_size(size, STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
dev_notice(&vdev->dev,
"new size: %llu %d-byte logical blocks (%s/%s)\n",
(unsigned long long)capacity,
queue_logical_block_size(q),
cap_str_10, cap_str_2);
set_capacity(vblk->disk, capacity);
}
static void virtblk_config_changed(struct virtio_device *vdev)
{
struct virtio_blk *vblk = vdev->priv;
queue_work(virtblk_wq, &vblk->config_work);
}
static int __devinit virtblk_probe(struct virtio_device *vdev)
{
struct virtio_blk *vblk;
......@@ -327,6 +373,7 @@ static int __devinit virtblk_probe(struct virtio_device *vdev)
vblk->vdev = vdev;
vblk->sg_elems = sg_elems;
sg_init_table(vblk->sg, vblk->sg_elems);
INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
/* We expect one virtqueue, for output. */
vblk->vq = virtio_find_single_vq(vdev, blk_done, "requests");
......@@ -477,6 +524,8 @@ static void __devexit virtblk_remove(struct virtio_device *vdev)
{
struct virtio_blk *vblk = vdev->priv;
flush_work(&vblk->config_work);
/* Nothing should be pending. */
BUG_ON(!list_empty(&vblk->reqs));
......@@ -508,27 +557,47 @@ static unsigned int features[] = {
* Use __refdata to avoid this warning.
*/
static struct virtio_driver __refdata virtio_blk = {
.feature_table = features,
.feature_table_size = ARRAY_SIZE(features),
.driver.name = KBUILD_MODNAME,
.driver.owner = THIS_MODULE,
.id_table = id_table,
.probe = virtblk_probe,
.remove = __devexit_p(virtblk_remove),
.feature_table = features,
.feature_table_size = ARRAY_SIZE(features),
.driver.name = KBUILD_MODNAME,
.driver.owner = THIS_MODULE,
.id_table = id_table,
.probe = virtblk_probe,
.remove = __devexit_p(virtblk_remove),
.config_changed = virtblk_config_changed,
};
static int __init init(void)
{
int error;
virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
if (!virtblk_wq)
return -ENOMEM;
major = register_blkdev(0, "virtblk");
if (major < 0)
return major;
return register_virtio_driver(&virtio_blk);
if (major < 0) {
error = major;
goto out_destroy_workqueue;
}
error = register_virtio_driver(&virtio_blk);
if (error)
goto out_unregister_blkdev;
return 0;
out_unregister_blkdev:
unregister_blkdev(major, "virtblk");
out_destroy_workqueue:
destroy_workqueue(virtblk_wq);
return error;
}
static void __exit fini(void)
{
unregister_blkdev(major, "virtblk");
unregister_virtio_driver(&virtio_blk);
destroy_workqueue(virtblk_wq);
}
module_init(init);
module_exit(fini);
......
......@@ -1677,17 +1677,12 @@ static int __devinit virtcons_probe(struct virtio_device *vdev)
portdev->config.max_nr_ports = 1;
if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT)) {
multiport = true;
vdev->features[0] |= 1 << VIRTIO_CONSOLE_F_MULTIPORT;
vdev->config->get(vdev, offsetof(struct virtio_console_config,
max_nr_ports),
&portdev->config.max_nr_ports,
sizeof(portdev->config.max_nr_ports));
}
/* Let the Host know we support multiple ports.*/
vdev->config->finalize_features(vdev);
err = init_vqs(portdev);
if (err < 0) {
dev_err(&vdev->dev, "Error %d initializing vqs\n", err);
......
......@@ -609,7 +609,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
* before it gets out of hand. Naturally, this wastes entries. */
if (capacity < 2+MAX_SKB_FRAGS) {
netif_stop_queue(dev);
if (unlikely(!virtqueue_enable_cb(vi->svq))) {
if (unlikely(!virtqueue_enable_cb_delayed(vi->svq))) {
/* More just got used, free them then recheck. */
capacity += free_old_xmit_skbs(vi);
if (capacity >= 2+MAX_SKB_FRAGS) {
......
......@@ -144,7 +144,7 @@ static void handle_tx(struct vhost_net *net)
}
mutex_lock(&vq->mutex);
vhost_disable_notify(vq);
vhost_disable_notify(&net->dev, vq);
if (wmem < sock->sk->sk_sndbuf / 2)
tx_poll_stop(net);
......@@ -166,8 +166,8 @@ static void handle_tx(struct vhost_net *net)
set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
break;
}
if (unlikely(vhost_enable_notify(vq))) {
vhost_disable_notify(vq);
if (unlikely(vhost_enable_notify(&net->dev, vq))) {
vhost_disable_notify(&net->dev, vq);
continue;
}
break;
......@@ -315,7 +315,7 @@ static void handle_rx(struct vhost_net *net)
return;
mutex_lock(&vq->mutex);
vhost_disable_notify(vq);
vhost_disable_notify(&net->dev, vq);
vhost_hlen = vq->vhost_hlen;
sock_hlen = vq->sock_hlen;
......@@ -334,10 +334,10 @@ static void handle_rx(struct vhost_net *net)
break;
/* OK, now we need to know about added descriptors. */
if (!headcount) {
if (unlikely(vhost_enable_notify(vq))) {
if (unlikely(vhost_enable_notify(&net->dev, vq))) {
/* They have slipped one in as we were
* doing that: check again. */
vhost_disable_notify(vq);
vhost_disable_notify(&net->dev, vq);
continue;
}
/* Nothing new? Wait for eventfd to tell us
......
......@@ -49,7 +49,7 @@ static void handle_vq(struct vhost_test *n)
return;
mutex_lock(&vq->mutex);
vhost_disable_notify(vq);
vhost_disable_notify(&n->dev, vq);
for (;;) {
head = vhost_get_vq_desc(&n->dev, vq, vq->iov,
......@@ -61,8 +61,8 @@ static void handle_vq(struct vhost_test *n)
break;
/* Nothing new? Wait for eventfd to tell us they refilled. */
if (head == vq->num) {
if (unlikely(vhost_enable_notify(vq))) {
vhost_disable_notify(vq);
if (unlikely(vhost_enable_notify(&n->dev, vq))) {
vhost_disable_notify(&n->dev, vq);
continue;
}
break;
......
......@@ -37,6 +37,9 @@ enum {
VHOST_MEMORY_F_LOG = 0x1,
};
#define vhost_used_event(vq) ((u16 __user *)&vq->avail->ring[vq->num])
#define vhost_avail_event(vq) ((u16 __user *)&vq->used->ring[vq->num])
static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
poll_table *pt)
{
......@@ -161,6 +164,8 @@ static void vhost_vq_reset(struct vhost_dev *dev,
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;
......@@ -489,16 +494,17 @@ static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
return 1;
}
static int vq_access_ok(unsigned int num,
static int vq_access_ok(struct vhost_dev *d, unsigned int num,
struct vring_desc __user *desc,
struct vring_avail __user *avail,
struct vring_used __user *used)
{
size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
access_ok(VERIFY_READ, avail,
sizeof *avail + num * sizeof *avail->ring) &&
sizeof *avail + num * sizeof *avail->ring + s) &&
access_ok(VERIFY_WRITE, used,
sizeof *used + num * sizeof *used->ring);
sizeof *used + num * sizeof *used->ring + s);
}
/* Can we log writes? */
......@@ -514,9 +520,11 @@ int vhost_log_access_ok(struct vhost_dev *dev)
/* 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)
static int vq_log_access_ok(struct vhost_dev *d, struct vhost_virtqueue *vq,
void __user *log_base)
{
struct vhost_memory *mp;
size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
mp = rcu_dereference_protected(vq->dev->memory,
lockdep_is_held(&vq->mutex));
......@@ -524,15 +532,15 @@ static int vq_log_access_ok(struct vhost_virtqueue *vq, void __user *log_base)
vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
(!vq->log_used || log_access_ok(log_base, vq->log_addr,
sizeof *vq->used +
vq->num * sizeof *vq->used->ring));
vq->num * sizeof *vq->used->ring + s));
}
/* Can we start vq? */
/* Caller should have vq mutex and device mutex */
int vhost_vq_access_ok(struct vhost_virtqueue *vq)
{
return vq_access_ok(vq->num, vq->desc, vq->avail, vq->used) &&
vq_log_access_ok(vq, vq->log_base);
return vq_access_ok(vq->dev, vq->num, vq->desc, vq->avail, vq->used) &&
vq_log_access_ok(vq->dev, vq, vq->log_base);
}
static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
......@@ -577,6 +585,7 @@ static int init_used(struct vhost_virtqueue *vq,
if (r)
return r;
vq->signalled_used_valid = false;
return get_user(vq->last_used_idx, &used->idx);
}
......@@ -674,7 +683,7 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
* 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->num,
if (!vq_access_ok(d, vq->num,
(void __user *)(unsigned long)a.desc_user_addr,
(void __user *)(unsigned long)a.avail_user_addr,
(void __user *)(unsigned long)a.used_user_addr)) {
......@@ -818,7 +827,7 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg)
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))
if (vq->private_data && !vq_log_access_ok(d, vq, base))
r = -EFAULT;
else
vq->log_base = base;
......@@ -1219,6 +1228,10 @@ int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
/* 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;
}
......@@ -1267,6 +1280,12 @@ int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
eventfd_signal(vq->log_ctx, 1);
}
vq->last_used_idx++;
/* 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(vq->last_used_idx == vq->signalled_used))
vq->signalled_used_valid = false;
return 0;
}
......@@ -1275,6 +1294,7 @@ static int __vhost_add_used_n(struct vhost_virtqueue *vq,
unsigned count)
{
struct vring_used_elem __user *used;
u16 old, new;
int start;
start = vq->last_used_idx % vq->num;
......@@ -1292,7 +1312,14 @@ static int __vhost_add_used_n(struct vhost_virtqueue *vq,
((void __user *)used - (void __user *)vq->used),
count * sizeof *used);
}
vq->last_used_idx += count;
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;
}
......@@ -1331,29 +1358,47 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
return r;
}
/* This actually signals the guest, using eventfd. */
void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
{
__u16 flags;
__u16 old, new, event;
bool v;
/* Flush out used index updates. This is paired
* with the barrier that the Guest executes when enabling
* interrupts. */
smp_mb();
if (__get_user(flags, &vq->avail->flags)) {
vq_err(vq, "Failed to get flags");
return;
if (vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
unlikely(vq->avail_idx == vq->last_avail_idx))
return true;
if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
__u16 flags;
if (__get_user(flags, &vq->avail->flags)) {
vq_err(vq, "Failed to get flags");
return true;
}
return !(flags & VRING_AVAIL_F_NO_INTERRUPT);
}
old = vq->signalled_used;
v = vq->signalled_used_valid;
new = vq->signalled_used = vq->last_used_idx;
vq->signalled_used_valid = true;
/* If they don't want an interrupt, don't signal, unless empty. */
if ((flags & VRING_AVAIL_F_NO_INTERRUPT) &&
(vq->avail_idx != vq->last_avail_idx ||
!vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY)))
return;
if (unlikely(!v))
return true;
if (get_user(event, vhost_used_event(vq))) {
vq_err(vq, "Failed to get used event idx");
return true;
}
return vring_need_event(event, new, old);
}
/* This actually signals the guest, using eventfd. */
void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
{
/* Signal the Guest tell them we used something up. */
if (vq->call_ctx)
if (vq->call_ctx && vhost_notify(dev, vq))
eventfd_signal(vq->call_ctx, 1);
}
......@@ -1376,7 +1421,7 @@ void vhost_add_used_and_signal_n(struct vhost_dev *dev,
}
/* OK, now we need to know about added descriptors. */
bool vhost_enable_notify(struct vhost_virtqueue *vq)
bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
{
u16 avail_idx;
int r;
......@@ -1384,11 +1429,34 @@ bool vhost_enable_notify(struct vhost_virtqueue *vq)
if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
return false;
vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
r = put_user(vq->used_flags, &vq->used->flags);
if (r) {
vq_err(vq, "Failed to enable notification at %p: %d\n",
&vq->used->flags, r);
return false;
if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
r = put_user(vq->used_flags, &vq->used->flags);
if (r) {
vq_err(vq, "Failed to enable notification at %p: %d\n",
&vq->used->flags, r);
return false;
}
} else {
r = put_user(vq->avail_idx, vhost_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;
}
}
if (unlikely(vq->log_used)) {
void __user *used;
/* Make sure data is seen before log. */
smp_wmb();
used = vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX) ?
&vq->used->flags : vhost_avail_event(vq);
/* Log used flags or event index entry write. Both are 16 bit
* fields. */
log_write(vq->log_base, vq->log_addr +
(used - (void __user *)vq->used),
sizeof(u16));
if (vq->log_ctx)
eventfd_signal(vq->log_ctx, 1);
}
/* They could have slipped one in as we were doing that: make
* sure it's written, then check again. */
......@@ -1404,15 +1472,17 @@ bool vhost_enable_notify(struct vhost_virtqueue *vq)
}
/* We don't need to be notified again. */
void vhost_disable_notify(struct vhost_virtqueue *vq)
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;
r = put_user(vq->used_flags, &vq->used->flags);
if (r)
vq_err(vq, "Failed to enable notification at %p: %d\n",
&vq->used->flags, r);
if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
r = put_user(vq->used_flags, &vq->used->flags);
if (r)
vq_err(vq, "Failed to enable notification at %p: %d\n",
&vq->used->flags, r);
}
}
......@@ -84,6 +84,12 @@ struct vhost_virtqueue {
/* Used flags */
u16 used_flags;
/* Last used index value we have signalled on */
u16 signalled_used;
/* Last used index value we have signalled on */
bool signalled_used_valid;
/* Log writes to used structure. */
bool log_used;
u64 log_addr;
......@@ -149,8 +155,8 @@ void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
struct vring_used_elem *heads, unsigned count);
void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
void vhost_disable_notify(struct vhost_virtqueue *);
bool vhost_enable_notify(struct vhost_virtqueue *);
void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
bool vhost_enable_notify(struct vhost_dev