Re: [RFC v2 08/14] virtio-net: detect VirtIONet status mid-migration change

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

On 3/24/26 7:26 AM, Eugenio Perez Martin wrote:
> On Fri, Mar 20, 2026 at 3:21 PM Jonah Palmer <jonah.palmer@oracle.com> wrote:
>>
>> Save VirtIONet's status field during early migration and compare it
>> again during stop-and-copy.
>>
>> VirtIONet keeps its own status bits here, including VIRTIO_NET_S_LINK_UP
>> and VIRTIO_NET_S_ANNOUNCE.
>>
> 
> These are particular to the device, so we don't need to migrate them.
> If any, we should check if the destination device changed the link
> state so we can update the guest, but we don't do that as far as I
> know.
> 

Sorry I might be misunderstanding something, but isn't VirtIONet's 
status member being migrated today (vmstate_virtio_net_device)?

>> Signed-off-by: Jonah Palmer <jonah.palmer@oracle.com>
>> ---
>>   hw/net/virtio-net.c            | 6 ++++++
>>   include/hw/virtio/virtio-net.h | 2 ++
>>   2 files changed, 8 insertions(+)
>>
>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
>> index 2dd130777e..88ce33b1d2 100644
>> --- a/hw/net/virtio-net.c
>> +++ b/hw/net/virtio-net.c
>> @@ -3872,6 +3872,7 @@ static int virtio_net_early_pre_save(void *opaque)
>>       VirtIONetMigration *vnet_mig = n->migration;
>>
>>       vdev_mig->status_early = vdev->status;
>> +    vnet_mig->status_early = n->status;
>>
>>       /* VirtIODevice config buffer snapshot */
>>       g_free(vdev_mig->config_early);
>> @@ -4304,6 +4305,11 @@ static bool virtio_net_has_delta(VirtIONet *n, VirtIODevice *vdev)
>>           return true;
>>       }
>>
>> +    /* Has the VirtIONet's status changed? */
>> +    if (n->status != vnet_mig->status_early) {
>> +        return true;
>> +    }
>> +
>>       /* Has the VirtIONet's MAC info changed? */
>>       if (memcmp(n->mac, vnet_mig->mac_early, ETH_ALEN) != 0) {
>>           return true;
>> diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
>> index 1e1f1a3995..59345f1811 100644
>> --- a/include/hw/virtio/virtio-net.h
>> +++ b/include/hw/virtio/virtio-net.h
>> @@ -169,6 +169,7 @@ typedef struct VirtIONetQueue {
>>
>>   /**
>>    * struct VirtIONetMigration - VirtIONet migration structure
>> + * @status_early: VirtIONet status snapshot.
>>    * @mac_early: MAC address early migration snapshot.
>>    * @mtable_in_use_early: In-use MAC table entries.
>>    * @mtable_uni_overflow_early: Unicast overflow MAC table entries.
>> @@ -176,6 +177,7 @@ typedef struct VirtIONetQueue {
>>    * @mtable_macs_early: MAC table entries.
>>    */
>>   typedef struct VirtIONetMigration {
>> +    uint16_t status_early;
>>       uint8_t mac_early[ETH_ALEN];
>>       uint32_t mtable_in_use_early;
>>       uint8_t mtable_uni_overflow_early;
>> --
>> 2.51.0
>>
>