static void reset_device(struct device *dev)
{
struct virtqueue *vq;
verbose("Resetting device %s\n", dev->name);
memset(get_feature_bits(dev) + dev->feature_len, 0, dev->feature_len);
signal(SIGCHLD, SIG_IGN);
for (vq = dev->vq; vq; vq = vq->next) {
if (vq->thread != (pid_t)-1) {
kill(vq->thread, SIGTERM);
waitpid(vq->thread, NULL, 0);
vq->thread = (pid_t)-1;
}
memset(vq->vring.desc, 0,
vring_size(vq->config.num, LGUEST_VRING_ALIGN));
lg_last_avail(vq) = 0;
}
dev->running = false;
signal(SIGCHLD, (void *)kill_launcher);
}
static void reset_device(struct device *dev)
{
struct virtqueue *vq;
verbose("Resetting device %s\n", dev->name);
/* Clear any features they've acked. */
memset(get_feature_bits(dev) + dev->feature_len, 0, dev->feature_len);
/* We're going to be explicitly killing threads, so ignore them. */
signal(SIGCHLD, SIG_IGN);
/* Zero out the virtqueues, get rid of their threads */
for (vq = dev->vq; vq; vq = vq->next) {
if (vq->thread != (pid_t)-1) {
kill(vq->thread, SIGTERM);
waitpid(vq->thread, NULL, 0);
vq->thread = (pid_t)-1;
}
memset(vq->vring.desc, 0,
vring_size(vq->config.num, LGUEST_VRING_ALIGN));
lg_last_avail(vq) = 0;
}
dev->running = false;
/* Now we care if threads die. */
signal(SIGCHLD, (void *)kill_launcher);
}
static unsigned wait_for_vq_desc(struct virtqueue *vq,
struct iovec iov[],
unsigned int *out_num, unsigned int *in_num)
{
unsigned int i, head, max;
struct vring_desc *desc;
u16 last_avail = lg_last_avail(vq);
while (last_avail == vq->vring.avail->idx) {
u64 event;
trigger_irq(vq);
vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
/*
* They could have slipped one in as we were doing that: make
* sure it's written, then check again.
*/
mb();
if (last_avail != vq->vring.avail->idx) {
vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
break;
}
if (read(vq->eventfd, &event, sizeof(event)) != sizeof(event))
errx(1, "Event read failed?");
vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
}
if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num)
errx(1, "Guest moved used index from %u to %u",
last_avail, vq->vring.avail->idx);
head = vq->vring.avail->ring[last_avail % vq->vring.num];
lg_last_avail(vq)++;
if (head >= vq->vring.num)
errx(1, "Guest says index %u is available", head);
*out_num = *in_num = 0;
max = vq->vring.num;
desc = vq->vring.desc;
i = head;
if (desc[i].flags & VRING_DESC_F_INDIRECT) {
if (desc[i].len % sizeof(struct vring_desc))
errx(1, "Invalid size for indirect buffer table");
max = desc[i].len / sizeof(struct vring_desc);
desc = check_pointer(desc[i].addr, desc[i].len);
i = 0;
}
do {
iov[*out_num + *in_num].iov_len = desc[i].len;
iov[*out_num + *in_num].iov_base
= check_pointer(desc[i].addr, desc[i].len);
if (desc[i].flags & VRING_DESC_F_WRITE)
(*in_num)++;
else {
if (*in_num)
errx(1, "Descriptor has out after in");
(*out_num)++;
}
if (*out_num + *in_num > max)
errx(1, "Looped descriptor");
} while ((i = next_desc(desc, i, max)) != max);
return head;
}
/*
* This looks in the virtqueue 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 waits if necessary, and returns the descriptor number found.
*/
static unsigned wait_for_vq_desc(struct virtqueue *vq,
struct iovec iov[],
unsigned int *out_num, unsigned int *in_num)
{
unsigned int i, head, max;
struct vring_desc *desc;
u16 last_avail = lg_last_avail(vq);
/* There's nothing available? */
while (last_avail == vq->vring.avail->idx) {
u64 event;
/*
* Since we're about to sleep, now is a good time to tell the
* Guest about what we've used up to now.
*/
trigger_irq(vq);
/* OK, now we need to know about added descriptors. */
vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
/*
* They could have slipped one in as we were doing that: make
* sure it's written, then check again.
*/
mb();
if (last_avail != vq->vring.avail->idx) {
vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
break;
}
/* Nothing new? Wait for eventfd to tell us they refilled. */
if (read(vq->eventfd, &event, sizeof(event)) != sizeof(event))
errx(1, "Event read failed?");
/* We don't need to be notified again. */
vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
}
/* Check it isn't doing very strange things with descriptor numbers. */
if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num)
errx(1, "Guest moved used index from %u to %u",
last_avail, vq->vring.avail->idx);
/*
* Grab the next descriptor number they're advertising, and increment
* the index we've seen.
*/
head = vq->vring.avail->ring[last_avail % vq->vring.num];
lg_last_avail(vq)++;
/* If their number is silly, that's a fatal mistake. */
if (head >= vq->vring.num)
errx(1, "Guest says index %u is available", head);
/* When we start there are none of either input nor output. */
*out_num = *in_num = 0;
max = vq->vring.num;
desc = vq->vring.desc;
i = head;
/*
* If this is an indirect entry, then this buffer contains a descriptor
* table which we handle as if it's any normal descriptor chain.
*/
if (desc[i].flags & VRING_DESC_F_INDIRECT) {
if (desc[i].len % sizeof(struct vring_desc))
errx(1, "Invalid size for indirect buffer table");
max = desc[i].len / sizeof(struct vring_desc);
desc = check_pointer(desc[i].addr, desc[i].len);
i = 0;
}
do {
/* Grab the first descriptor, and check it's OK. */
iov[*out_num + *in_num].iov_len = desc[i].len;
iov[*out_num + *in_num].iov_base
= check_pointer(desc[i].addr, desc[i].len);
/* If this is an input descriptor, increment that count. */
if (desc[i].flags & VRING_DESC_F_WRITE)
(*in_num)++;
else {
/*
* If it's an output descriptor, they're all supposed
* to come before any input descriptors.
*/
if (*in_num)
errx(1, "Descriptor has out after in");
(*out_num)++;
}
/* If we've got too many, that implies a descriptor loop. */
if (*out_num + *in_num > max)
errx(1, "Looped descriptor");
} while ((i = next_desc(desc, i, max)) != max);
return head;
}
