@@ -53,6 +53,9 @@ uint64_t vhost_net_get_features(struct vhost_net *net, uint64_t features)
if (!(net->dev.features & (1ULL << VIRTIO_RING_F_USED_EVENT_IDX))) {
features &= ~(1ULL << VIRTIO_RING_F_USED_EVENT_IDX);
}
+ if (!(net->dev.features & (1ULL << VIRTIO_RING_F_AVAIL_EVENT_IDX))) {
+ features &= ~(1ULL << VIRTIO_RING_F_AVAIL_EVENT_IDX);
+ }
if (!(net->dev.features & (1 << VIRTIO_NET_F_MRG_RXBUF))) {
features &= ~(1 << VIRTIO_NET_F_MRG_RXBUF);
}
@@ -71,6 +74,9 @@ void vhost_net_ack_features(struct vhost_net *net, uint64_t features)
if (features & (1ULL << VIRTIO_RING_F_USED_EVENT_IDX)) {
net->dev.acked_features |= (1ULL << VIRTIO_RING_F_USED_EVENT_IDX);
}
+ if (features & (1ULL << VIRTIO_RING_F_AVAIL_EVENT_IDX)) {
+ net->dev.acked_features |= (1ULL << VIRTIO_RING_F_AVAIL_EVENT_IDX);
+ }
if (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) {
net->dev.acked_features |= (1 << VIRTIO_NET_F_MRG_RXBUF);
}
@@ -78,6 +78,9 @@ struct VirtQueue
/* Last used index value we have signalled on */
bool signalled_used_valid;
+ /* Notification enabled? */
+ bool notification;
+
int inuse;
uint16_t vector;
@@ -195,12 +198,26 @@ static inline void vring_used_flags_unset_bit(VirtQueue *vq, int mask)
stw_phys(pa, lduw_phys(pa) & ~mask);
}
+static inline void vring_avail_event(VirtQueue *vq, uint16_t val)
+{
+ target_phys_addr_t pa;
+ if (!vq->notification) {
+ return;
+ }
+ pa = vq->vring.used + offsetof(VRingUsed, ring[vq->vring.num]);
+ stw_phys(pa, val);
+}
+
void virtio_queue_set_notification(VirtQueue *vq, int enable)
{
- if (enable)
+ vq->notification = enable;
+ if (vq->vdev->guest_features & (1ULL << VIRTIO_RING_F_AVAIL_EVENT_IDX)) {
+ vring_avail_event(vq, vq->last_avail_idx);
+ } else if (enable) {
vring_used_flags_unset_bit(vq, VRING_USED_F_NO_NOTIFY);
- else
+ } else {
vring_used_flags_set_bit(vq, VRING_USED_F_NO_NOTIFY);
+ }
}
int virtio_queue_ready(VirtQueue *vq)
@@ -412,6 +429,9 @@ int virtqueue_pop(VirtQueue *vq, VirtQueueElement *elem)
max = vq->vring.num;
i = head = virtqueue_get_head(vq, vq->last_avail_idx++);
+ if (vq->vdev->guest_features & (1ULL << VIRTIO_RING_F_AVAIL_EVENT_IDX)) {
+ vring_avail_event(vq, vq->last_avail_idx);
+ }
if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_INDIRECT) {
if (vring_desc_len(desc_pa, i) % sizeof(VRingDesc)) {
@@ -497,6 +517,7 @@ void virtio_reset(void *opaque)
vdev->vq[i].vector = VIRTIO_NO_VECTOR;
vdev->vq[i].signalled_used = 0;
vdev->vq[i].signalled_used_valid = false;
+ vdev->vq[i].notification = true;
}
}
@@ -784,6 +805,7 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f)
vdev->vq[i].pa = 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;
if (vdev->vq[i].pa) {
uint16_t nheads;
@@ -54,6 +54,9 @@
/* Enables feature bits 32 to 63 (only really required for virtio_pci). */
#define VIRTIO_F_FEATURES_HI 31
+/* The Host publishes the avail index for which it expects a kick
+ * at the end of the used ring. Guest should ignore the used->flags field. */
+#define VIRTIO_RING_F_AVAIL_EVENT_IDX 32
/* from Linux's linux/virtio_ring.h */
@@ -218,7 +221,9 @@ void virtio_serial_exit(VirtIODevice *vdev);
DEFINE_PROP_BIT64("indirect_desc", _state, _field, \
VIRTIO_RING_F_INDIRECT_DESC, true), \
DEFINE_PROP_BIT64("used_event", _state, _field, \
- VIRTIO_RING_F_USED_EVENT_IDX, true)
+ VIRTIO_RING_F_USED_EVENT_IDX, true), \
+ DEFINE_PROP_BIT64("avail_event", _state, _field, \
+ VIRTIO_RING_F_AVAIL_EVENT_IDX, true)
target_phys_addr_t virtio_queue_get_desc_addr(VirtIODevice *vdev, int n);
target_phys_addr_t virtio_queue_get_avail_addr(VirtIODevice *vdev, int n);
Reduce the number of exits utilizing the avail_event feature. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- hw/vhost_net.c | 6 ++++++ hw/virtio.c | 26 ++++++++++++++++++++++++-- hw/virtio.h | 7 ++++++- 3 files changed, 36 insertions(+), 3 deletions(-)