virtio-pci: fix 1.0 virtqueue migration

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>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/hw/virtio/virtio-bus.h b/include/hw/virtio/virtio-bus.h
index 8811415..6c3d4cb 100644
--- a/include/hw/virtio/virtio-bus.h
+++ b/include/hw/virtio/virtio-bus.h
@@ -44,9 +44,12 @@ typedef struct VirtioBusClass {
     void (*notify)(DeviceState *d, uint16_t vector);
     void (*save_config)(DeviceState *d, QEMUFile *f);
     void (*save_queue)(DeviceState *d, int n, QEMUFile *f);
+    void (*save_extra_state)(DeviceState *d, QEMUFile *f);
     int (*load_config)(DeviceState *d, QEMUFile *f);
     int (*load_queue)(DeviceState *d, int n, QEMUFile *f);
     int (*load_done)(DeviceState *d, QEMUFile *f);
+    int (*load_extra_state)(DeviceState *d, QEMUFile *f);
+    bool (*has_extra_state)(DeviceState *d);
     bool (*query_guest_notifiers)(DeviceState *d);
     int (*set_guest_notifiers)(DeviceState *d, int nvqs, bool assign);
     int (*set_host_notifier)(DeviceState *d, int n, bool assigned);