[RFC v2 11/14] virtio-net: detect VirtIONet guest offload & MQ mid-migration changes

[Jonah Palmer <jonah.palmer@oracle.com>]

Save the state of virtio-net's guest offloads and multiqueue
configuration at early migration time to compare with later during
the stop-and-copy phase.

Signed-off-by: Jonah Palmer <jonah.palmer@oracle.com>
---
 hw/net/virtio-net.c            | 20 ++++++++++++++++++++
 include/hw/virtio/virtio-net.h |  6 ++++++
 2 files changed, 26 insertions(+)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index b3f71d8f84..2c0b42debb 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -3936,6 +3936,13 @@ static int virtio_net_early_pre_save(void *opaque)
     }
     memcpy(vnet_mig->vlans_early, n->vlans, vlans_size);
 
+    /* Guest offloads snapshot */
+    vnet_mig->guest_offloads_early = n->curr_guest_offloads;
+
+    /* Multiqueue state snapshot */
+    vnet_mig->mq_early = n->multiqueue;
+    vnet_mig->queue_pairs_early = n->curr_queue_pairs;
+
     return 0;
 }
 
@@ -4369,6 +4376,19 @@ static bool virtio_net_has_delta(VirtIONet *n, VirtIODevice *vdev)
         return true;
     }
 
+    /* Has the VirtIONet's guest offloads changed? */
+    if (n->curr_guest_offloads != vnet_mig->guest_offloads_early) {
+        return true;
+    }
+
+    /* Has the VirtIONet's multiqueue state changed? */
+    if (n->multiqueue != vnet_mig->mq_early) {
+        return true;
+    }
+    if (n->curr_queue_pairs != vnet_mig->queue_pairs_early) {
+        return true;
+    }
+
     /*
      * Always return true for now until we're able to detect all possible
      * changes to a VirtIONet device.
diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
index 5df2dd0513..5d6179fa19 100644
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -177,6 +177,9 @@ typedef struct VirtIONetQueue {
  * @mtable_macs_early: MAC table entries.
  * @rx_flags_early: Bit-packed RX filters (promisc, allmulti, alluni, etc.).
  * @vlans_early: VLAN filter table snapshot.
+ * @guest_offloads_early: Guest offloads snapshot.
+ * @mq_early: Multiqueue state snapshot.
+ * @queue_pairs_early: Queue pairs snapshot.
  */
 typedef struct VirtIONetMigration {
     uint16_t status_early;
@@ -187,6 +190,9 @@ typedef struct VirtIONetMigration {
     uint8_t *mtable_macs_early;
     uint8_t rx_flags_early;
     uint8_t *vlans_early;
+    uint64_t guest_offloads_early;
+    int mq_early;
+    uint16_t queue_pairs_early;
 } VirtIONetMigration;
 
 struct VirtIONet {
-- 
2.51.0