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virtio: turn vq->notification into a nested counter 

Polling should disable virtqueue notifications but that requires nested
virtio_queue_set_notification() calls.  Turn vq->notification into a
counter so it is possible to do nesting.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20161201192652.9509-10-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2016-12-01 19:26:48 +00:00
parent 23425cc2b7
commit aff8fd18f1
1 changed files with 12 additions and 6 deletions
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18
hw/virtio/virtio.c
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@ -87,8 +87,8 @@ struct VirtQueue
/* Last used index value we have signalled on */
bool signalled_used_valid;
/* Notification enabled? */
bool notification;
/* Nested host->guest notification disabled counter */
unsigned int notification_disabled;
uint16_t queue_index;
@ -201,7 +201,7 @@ static inline void vring_used_flags_unset_bit(VirtQueue *vq, int mask)
static inline void vring_set_avail_event(VirtQueue *vq, uint16_t val)
{
hwaddr pa;
if (!vq->notification) {
if (vq->notification_disabled) {
return;
}
pa = vq->vring.used + offsetof(VRingUsed, ring[vq->vring.num]);
@ -210,7 +210,13 @@ static inline void vring_set_avail_event(VirtQueue *vq, uint16_t val)
void virtio_queue_set_notification(VirtQueue *vq, int enable)
{
vq->notification = enable;
if (enable) {
assert(vq->notification_disabled > 0);
vq->notification_disabled--;
} else {
vq->notification_disabled++;
}
if (virtio_vdev_has_feature(vq->vdev, VIRTIO_RING_F_EVENT_IDX)) {
vring_set_avail_event(vq, vring_avail_idx(vq));
} else if (enable) {
@ -959,7 +965,7 @@ void virtio_reset(void *opaque)
virtio_queue_set_vector(vdev, i, VIRTIO_NO_VECTOR);
vdev->vq[i].signalled_used = 0;
vdev->vq[i].signalled_used_valid = false;
vdev->vq[i].notification = true;
vdev->vq[i].notification_disabled = 0;
vdev->vq[i].vring.num = vdev->vq[i].vring.num_default;
vdev->vq[i].inuse = 0;
}
@ -1770,7 +1776,7 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
vdev->vq[i].vring.desc = qemu_get_be64(f);
qemu_get_be16s(f, &vdev->vq[i].last_avail_idx);
vdev->vq[i].signalled_used_valid = false;
vdev->vq[i].notification = true;
vdev->vq[i].notification_disabled = 0;
if (vdev->vq[i].vring.desc) {
/* XXX virtio-1 devices */