[RFC v2 10/14] virtio-net: detect VirtIONet VLAN filter table changes

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

Save the current state of virtio-net's VLAN filter table 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            | 14 ++++++++++++++
 include/hw/virtio/virtio-net.h |  2 ++
 2 files changed, 16 insertions(+)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 42c585142d..b3f71d8f84 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -3890,6 +3890,7 @@ static int virtio_net_early_pre_save(void *opaque)
     VirtIODevice *vdev = VIRTIO_DEVICE(n);
     VirtIODevMigration *vdev_mig = vdev->migration;
     VirtIONetMigration *vnet_mig = n->migration;
+    size_t vlans_size = (size_t)(MAX_VLAN >> 3);
 
     vdev_mig->status_early = vdev->status;
     vnet_mig->status_early = n->status;
@@ -3929,6 +3930,12 @@ static int virtio_net_early_pre_save(void *opaque)
     /* Rx filter flags snapshot */
     vnet_mig->rx_flags_early = virtio_net_rx_flags_pack(n);
 
+    /* VLAN filter table snapshot */
+    if (!vnet_mig->vlans_early) {
+        vnet_mig->vlans_early = g_malloc0(vlans_size);
+    }
+    memcpy(vnet_mig->vlans_early, n->vlans, vlans_size);
+
     return 0;
 }
 
@@ -4217,6 +4224,8 @@ static void virtio_net_device_unrealize(DeviceState *dev)
 
         g_free(n->migration->mtable_macs_early);
         n->migration->mtable_macs_early = NULL;
+        g_free(n->migration->vlans_early);
+        n->migration->vlans_early = NULL;
         g_free(n->migration);
         n->migration = NULL;
 
@@ -4355,6 +4364,11 @@ static bool virtio_net_has_delta(VirtIONet *n, VirtIODevice *vdev)
         return true;
     }
 
+    /* Has the VirtIONet's VLAN filter table changed? */
+    if (memcmp(n->vlans, vnet_mig->vlans_early, MAX_VLAN >> 3) != 0) {
+        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 9135d277ff..5df2dd0513 100644
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -176,6 +176,7 @@ typedef struct VirtIONetQueue {
  * @mtable_multi_overflow_early: Multicast overflow MAC table entries.
  * @mtable_macs_early: MAC table entries.
  * @rx_flags_early: Bit-packed RX filters (promisc, allmulti, alluni, etc.).
+ * @vlans_early: VLAN filter table snapshot.
  */
 typedef struct VirtIONetMigration {
     uint16_t status_early;
@@ -185,6 +186,7 @@ typedef struct VirtIONetMigration {
     uint8_t mtable_multi_overflow_early;
     uint8_t *mtable_macs_early;
     uint8_t rx_flags_early;
+    uint8_t *vlans_early;
 } VirtIONetMigration;
 
 struct VirtIONet {
-- 
2.51.0