static int virtqueue_num_heads(VirtQueue *vq, unsigned int idx)
{
uint16_t num_heads = vring_avail_idx(vq) - idx;
/* Check it isn't doing very strange things with descriptor numbers. */
if (num_heads > vq->vring.num) {
fprintf(stderr, "Guest moved used index from %u to %u",
idx, vring_avail_idx(vq));
exit(1);
}
return num_heads;
}
void virtio_queue_set_notification(VirtQueue *vq, int enable)
{
vq->notification = enable;
if (vq->vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX)) {
vring_avail_event(vq, vring_avail_idx(vq));
} else if (enable) {
vring_used_flags_unset_bit(vq, VRING_USED_F_NO_NOTIFY);
} else {
vring_used_flags_set_bit(vq, VRING_USED_F_NO_NOTIFY);
}
}
void virtio_queue_set_notification(VirtQueue *vq, int enable)
{
vq->notification = enable;
if (bUsePublishedIndices) {
vring_avail_event(vq, vring_avail_idx(vq));
} else if (enable) {
vring_used_flags_unset_bit(vq, VRING_USED_F_NO_NOTIFY);
} else {
vring_used_flags_set_bit(vq, VRING_USED_F_NO_NOTIFY);
}
}
void virtio_notify(VirtIODevice *vdev, VirtQueue *vq)
{
/* Always notify when queue is empty (when feature acknowledge) */
if ((vring_avail_flags(vq) & VRING_AVAIL_F_NO_INTERRUPT) &&
(!(vdev->guest_features & (1 << VIRTIO_F_NOTIFY_ON_EMPTY)) ||
(vq->inuse || vring_avail_idx(vq) != vq->last_avail_idx)))
return;
vdev->isr |= 0x01;
virtio_notify_vector(vdev, vq->vector);
}
/* Fetch avail_idx from VQ memory only when we really need to know if
* guest has added some buffers. */
bool
vu_queue_empty(VuDev *dev, VuVirtq *vq)
{
if (unlikely(dev->broken) ||
unlikely(!vq->vring.avail)) {
return true;
}
if (vq->shadow_avail_idx != vq->last_avail_idx) {
return false;
}
return vring_avail_idx(vq) == vq->last_avail_idx;
}
void virtio_queue_set_notification(VirtQueue *vq, int enable)
{
vq->notification = enable;
if (vq->vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX)) {
vring_avail_event(vq, vring_avail_idx(vq));
} else if (enable) {
vring_used_flags_unset_bit(vq, VRING_USED_F_NO_NOTIFY);
} else {
vring_used_flags_set_bit(vq, VRING_USED_F_NO_NOTIFY);
}
if (enable) {
/* Expose avail event/used flags before caller checks the avail idx. */
smp_mb();
}
}
static int
virtqueue_num_heads(VuDev *dev, VuVirtq *vq, unsigned int idx)
{
uint16_t num_heads = vring_avail_idx(vq) - idx;
/* Check it isn't doing very strange things with descriptor numbers. */
if (num_heads > vq->vring.num) {
vu_panic(dev, "Guest moved used index from %u to %u",
idx, vq->shadow_avail_idx);
return -1;
}
if (num_heads) {
/* On success, callers read a descriptor at vq->last_avail_idx.
* Make sure descriptor read does not bypass avail index read. */
smp_rmb();
}
return num_heads;
}
static bool vring_notify(PVOID unused, VirtQueue *vq)
{
uint16_t old, _new;
bool v;
/* Always notify when queue is empty (when feature acknowledge) */
//if (((vdev->guest_features & (1 << VIRTIO_F_NOTIFY_ON_EMPTY)) &&
if ((bVirtioF_NotifyOnEmpty &&
!vq->inuse && vring_avail_idx(vq) == vq->last_avail_idx)) {
return TRUE;
}
//if (!(vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX))) {
if (!bUsePublishedIndices) {
return !(vring_avail_flags(vq) & VRING_AVAIL_F_NO_INTERRUPT);
}
v = vq->signalled_used_valid;
vq->signalled_used_valid = TRUE;
old = vq->signalled_used;
_new = vq->signalled_used = vring_used_idx(vq);
return !v || vring_need_event(vring_used_event(vq), _new, old);
}
int virtio_queue_empty(VirtQueue *vq)
{
return vring_avail_idx(vq) == vq->last_avail_idx;
}