[2.4] virtio: fix 1.0 virtqueue migration

1.0 does not requires physically-contiguous pages layout for a
virtqueue. So we could not infer avail and used from desc. This means
we need to migrate vring.avail and vring.used when host support virtio
1.0. This fixes malfunction of virtio 1.0 device after migration.

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 hw/virtio/virtio.c         | 17 ++++++++++++++---
 include/hw/virtio/virtio.h |  6 ++++++
 2 files changed, 20 insertions(+), 3 deletions(-)

On Wed, Aug 05, 2015 at 02:12:26PM +0800, Jason Wang wrote:
> 1.0 does not requires physically-contiguous pages layout for a
> virtqueue. So we could not infer avail and used from desc. This means
> we need to migrate vring.avail and vring.used when host support virtio
> 1.0. This fixes malfunction of virtio 1.0 device after migration.
> 
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

I agree we want this in 2.4.

> ---
>  hw/virtio/virtio.c         | 17 ++++++++++++++---
>  include/hw/virtio/virtio.h |  6 ++++++
>  2 files changed, 20 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index ee4e07c..ae78253 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -1092,6 +1092,7 @@ void virtio_save(VirtIODevice *vdev, QEMUFile *f)
>      VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
>      VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
>      uint32_t guest_features_lo = (vdev->guest_features & 0xffffffff);
> +    bool version_1 = virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1);
>      int i;
>  
>      if (k->save_config) {
> @@ -1120,8 +1121,12 @@ void virtio_save(VirtIODevice *vdev, QEMUFile *f)
>          if (k->has_variable_vring_alignment) {
>              qemu_put_be32(f, vdev->vq[i].vring.align);
>          }
> -        /* XXX virtio-1 devices */
>          qemu_put_be64(f, vdev->vq[i].vring.desc);
> +        if (version_1) {
> +            qemu_put_be64(f, vdev->vq[i].vring.avail);
> +            qemu_put_be64(f, vdev->vq[i].vring.used);
> +        }
> +
>          qemu_put_be16s(f, &vdev->vq[i].last_avail_idx);
>          if (k->save_queue) {
>              k->save_queue(qbus->parent, i, f);
> @@ -1170,6 +1175,7 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
>      BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
>      VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
>      VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
> +    bool version_1 = virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1);
>  
>      /*
>       * We poison the endianness to ensure it does not get used before
> @@ -1218,13 +1224,18 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
>              vdev->vq[i].vring.align = qemu_get_be32(f);
>          }
>          vdev->vq[i].vring.desc = qemu_get_be64(f);
> +        if (version_1) {
> +            vdev->vq[i].vring.avail = qemu_get_be64(f);
> +            vdev->vq[i].vring.used = qemu_get_be64(f);
> +        }
>          qemu_get_be16s(f, &vdev->vq[i].last_avail_idx);
>          vdev->vq[i].signalled_used_valid = false;
>          vdev->vq[i].notification = true;
>  
>          if (vdev->vq[i].vring.desc) {
> -            /* XXX virtio-1 devices */
> -            virtio_queue_update_rings(vdev, i);
> +            if (!version_1) {
> +                virtio_queue_update_rings(vdev, i);
> +            }
>          } else if (vdev->vq[i].last_avail_idx) {
>              error_report("VQ %d address 0x0 "
>                           "inconsistent with Host index 0x%x",
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index 59f0763..cccae89 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -272,6 +272,12 @@ static inline bool virtio_has_feature(VirtIODevice *vdev, unsigned int fbit)
>      return __virtio_has_feature(vdev->guest_features, fbit);
>  }
>  
> +static inline bool virtio_host_has_feature(VirtIODevice *vdev,
> +                                           unsigned int fbit)
> +{
> +    return __virtio_has_feature(vdev->host_features, fbit);
> +}
> +
>  static inline bool virtio_is_big_endian(VirtIODevice *vdev)
>  {
>      if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
> -- 
> 2.1.4