Some dynamic state of a virtio-net vDPA devices is restored from CVQ in
the event of a live migration. However, dataplane needs to be disabled
so the NIC does not receive buffers in the invalid ring.
As a default method to achieve it, let's offer a shadow vring with 0
avail idx. As a fallback method, we will enable dataplane vqs later, as
proposed previously.
Signed-off-by: Eugenio Pérez <epere...@redhat.com>
---
net/vhost-vdpa.c | 49 +++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 44 insertions(+), 5 deletions(-)
diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index af83de92f8..e14ae48f23 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -338,10 +338,25 @@ static int vhost_vdpa_net_data_start(NetClientState *nc)
{
VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
struct vhost_vdpa *v = &s->vhost_vdpa;
+ bool has_cvq = v->dev->vq_index_end % 2;
assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA);
- if (s->always_svq ||
+ if (has_cvq && (v->dev->features & VIRTIO_F_RING_RESET)) {
+ /*
+ * Offer a fake vring to the device while the state is restored
+ * through CVQ. That way, the guest will not see packets in unexpected
+ * queues.
+ *
+ * This will be undone after loading all state through CVQ, at
+ * vhost_vdpa_net_load.
+ *
+ * TODO: Future optimizations may skip some SVQ setup and teardown,
+ * like set the right kick and call fd or doorbell maps directly, and
+ * the iova tree.
+ */
+ v->shadow_vqs_enabled = true;
+ } else if (s->always_svq ||
migration_is_setup_or_active(migrate_get_current()->state)) {
v->shadow_vqs_enabled = true;
v->shadow_data = true;
@@ -738,10 +753,34 @@ static int vhost_vdpa_net_load(NetClientState *nc)
return r;
}
- for (int i = 0; i < v->dev->vq_index; ++i) {
- r = vhost_vdpa_set_vring_ready(v, i);
- if (unlikely(r)) {
- return r;
+ if (v->dev->features & VIRTIO_F_RING_RESET && !s->always_svq &&
+ !migration_is_setup_or_active(migrate_get_current()->state)) {
+ NICState *nic = qemu_get_nic(s->nc.peer);
+ int queue_pairs = n->multiqueue ? n->max_queue_pairs : 1;
+
+ for (int i = 0; i < queue_pairs; ++i) {
+ NetClientState *ncs = qemu_get_peer(nic->ncs, i);
+ VhostVDPAState *s_i = DO_UPCAST(VhostVDPAState, nc, ncs);
+
+ for (int j = 0; j < 2; ++j) {
+ vhost_net_virtqueue_reset(v->dev->vdev, ncs->peer, j);
+ }
+
+ s_i->vhost_vdpa.shadow_vqs_enabled = false;
+
+ for (int j = 0; j < 2; ++j) {
+ r = vhost_net_virtqueue_restart(v->dev->vdev, ncs->peer, j);
+ if (unlikely(r < 0)) {
+ return r;
+ }
+ }
+ }
+ } else {
+ for (int i = 0; i < v->dev->vq_index; ++i) {
+ r = vhost_vdpa_set_vring_ready(v, i);
+ if (unlikely(r)) {
+ return r;
+ }
}
}
--
2.39.3
