Re: [Qemu-devel] [PATCH for 2.4 V2] virtio: fix 1.0 virtqueue migration

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Aug 05, 2015 at 05:50:07PM +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>
> Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

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

> ---
> - Changes from V1: switch to use subsection to make debug easier
> ---
>  hw/virtio/virtio.c         | 56 ++++++++++++++++++++++++++++++++++++++++++++++
>  include/hw/virtio/virtio.h |  6 +++++
>  2 files changed, 62 insertions(+)
> 
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index ee4e07c..788b556 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -1049,6 +1049,61 @@ static bool virtio_64bit_features_needed(void *opaque)
>      return (vdev->host_features >> 32) != 0;
>  }
>  
> +static bool virtio_virtqueue_needed(void *opaque)
> +{
> +    VirtIODevice *vdev = opaque;
> +
> +    return virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1);
> +}
> +
> +static void put_virtqueue_state(QEMUFile *f, void *pv, size_t size)
> +{
> +    VirtIODevice *vdev = pv;
> +    int i;
> +
> +    for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
> +        qemu_put_be64(f, vdev->vq[i].vring.avail);
> +        qemu_put_be64(f, vdev->vq[i].vring.used);
> +    }
> +}
> +
> +static int get_virtqueue_state(QEMUFile *f, void *pv, size_t size)
> +{
> +    VirtIODevice *vdev = pv;
> +    int i;
> +
> +    for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
> +        vdev->vq[i].vring.avail = qemu_get_be64(f);
> +        vdev->vq[i].vring.used = qemu_get_be64(f);
> +    }
> +    return 0;
> +}
> +
> +static VMStateInfo vmstate_info_virtqueue = {
> +    .name = "virtqueue_state",
> +    .get = get_virtqueue_state,
> +    .put = put_virtqueue_state,
> +};
> +
> +static const VMStateDescription vmstate_virtio_virtqueues = {
> +    .name = "virtio/virtqueues",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .needed = &virtio_virtqueue_needed,
> +    .fields = (VMStateField[]) {
> +        {
> +            .name         = "virtqueues",
> +            .version_id   = 0,
> +            .field_exists = NULL,
> +            .size         = 0,
> +            .info         = &vmstate_info_virtqueue,
> +            .flags        = VMS_SINGLE,
> +            .offset       = 0,
> +        },
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
>  static const VMStateDescription vmstate_virtio_device_endian = {
>      .name = "virtio/device_endian",
>      .version_id = 1,
> @@ -1082,6 +1137,7 @@ static const VMStateDescription vmstate_virtio = {
>      .subsections = (const VMStateDescription*[]) {
>          &vmstate_virtio_device_endian,
>          &vmstate_virtio_64bit_features,
> +        &vmstate_virtio_virtqueues,
>          NULL
>      }
>  };
> 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