Re: [Qemu-devel] [PATCH V3 1/6] virtio-pci: fix 1.0 virtqueue migration

[Jason Wang <jasowang@redhat.com>]

On 11/09/2015 08:56 PM, Cornelia Huck wrote:
> On Fri,  6 Nov 2015 16:02:44 +0800
> Jason Wang <jasowang@redhat.com> wrote:
>
>> We don't migrate the followings fields for virtio-pci:
>>
>> uint32_t dfselect;
>> uint32_t gfselect;
>> uint32_t guest_features[2];
>> struct {
>>     uint16_t num;
>>     bool enabled;
>>     uint32_t desc[2];
>>     uint32_t avail[2];
>>     uint32_t used[2];
>> } vqs[VIRTIO_QUEUE_MAX];
>>
>> This will confuse driver if migrating during initialization. Solves
>> this issue by:
>>
>> - introduce transport specific callbacks to load and store extra
>>   virtqueue states.
>> - add a new subsection for virtio to migrate transport specific modern
>>   device state.
>> - implement pci specific callbacks.
>> - add a new property for virtio-pci for whether or not to migrate
>>   extra state.
>> - compat the migration for 2.4 and elder machine types
>>
>> Cc: Michael S. Tsirkin <mst@redhat.com>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>>  hw/virtio/virtio-pci.c         | 129 +++++++++++++++++++++++++++++++++++++++++
>>  hw/virtio/virtio-pci.h         |  20 ++++---
>>  hw/virtio/virtio.c             |  58 ++++++++++++++++++
>>  include/hw/compat.h            |   4 ++
>>  include/hw/virtio/virtio-bus.h |   3 +
>>  5 files changed, 207 insertions(+), 7 deletions(-)
>> @@ -133,6 +256,7 @@ static int virtio_pci_load_queue(DeviceState *d, int n, QEMUFile *f)
>>      if (vector != VIRTIO_NO_VECTOR) {
>>          return msix_vector_use(&proxy->pci_dev, vector);
>>      }
>> +
> whitespace change :)

Right, I will wait for other comments to see if v4 is needed (and fix
there).

>>      return 0;
>>  }
>>
> (...)
>
>> +static void put_extra_state(QEMUFile *f, void *pv, size_t size)
>> +{
>> +    VirtIODevice *vdev = pv;
>> +    BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
>> +    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
>> +
> I'd probably put an 'assert(k->save_extra_state)' here. (I think we
> have discussed this before, but I can't recall the outcome.)

Yes, may help to hunt bugs earlier.

>
>> +    k->save_extra_state(qbus->parent, f);
>> +}
> Otherwise, this looks good to me. With or with out the assert,
>
> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
>
>