Re: [RFC PATCH v8 12/21] vdpa: delay set_vring_ready after DRIVER_OK

[Jason Wang]

在 2022/5/20 03:12, Eugenio Pérez 写道:
> To restore the device in the destination of a live migration we send the
> commands through control virtqueue. For a device to read CVQ it must
> have received DRIVER_OK status bit.
>
> However this open a window where the device could start receiving
> packets in rx queue 0 before it receive the RSS configuration. To avoid
> that, we will not send vring_enable until all configuration is used by
> the device.
>
> As a first step, reverse the DRIVER_OK and SET_VRING_ENABLE steps.
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>


I may miss something, but it looks to me this should be an independent 
patch or it should depend on live migration series.

Thanks


> ---
>   hw/virtio/vhost-vdpa.c | 20 +++++++++++++++-----
>   1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> index 31b3d4d013..13e5e2a061 100644
> --- a/hw/virtio/vhost-vdpa.c
> +++ b/hw/virtio/vhost-vdpa.c
> @@ -748,13 +748,18 @@ static int vhost_vdpa_get_vq_index(struct vhost_dev *dev, 
> int idx)
>       return idx;
>   }
>   
> +/**
> + * Set ready all vring of the device
> + *
> + * @dev: Vhost device
> + */
>   static int vhost_vdpa_set_vring_ready(struct vhost_dev *dev)
>   {
>       int i;
>       trace_vhost_vdpa_set_vring_ready(dev);
> -    for (i = 0; i < dev->nvqs; ++i) {
> +    for (i = 0; i < dev->vq_index_end; ++i) {
>           struct vhost_vring_state state = {
> -            .index = dev->vq_index + i,
> +            .index = i,
>               .num = 1,
>           };
>           vhost_vdpa_call(dev, VHOST_VDPA_SET_VRING_ENABLE, &state);
> @@ -1117,7 +1122,6 @@ static int vhost_vdpa_dev_start(struct vhost_dev *dev, 
> bool started)
>           if (unlikely(!ok)) {
>               return -1;
>           }
> -        vhost_vdpa_set_vring_ready(dev);
>       } else {
>           ok = vhost_vdpa_svqs_stop(dev);
>           if (unlikely(!ok)) {
> @@ -1131,16 +1135,22 @@ static int vhost_vdpa_dev_start(struct vhost_dev *dev, 
> bool started)
>       }
>   
>       if (started) {
> +        int r;
>           memory_listener_register(&v->listener, &address_space_memory);
> -        return vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
> +        r = vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
> +        if (unlikely(r)) {
> +            return r;
> +        }
> +        vhost_vdpa_set_vring_ready(dev);
>       } else {
>           vhost_vdpa_reset_device(dev);
>           vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE |
>                                      VIRTIO_CONFIG_S_DRIVER);
>           memory_listener_unregister(&v->listener);
>   
> -        return 0;
>       }
> +
> +    return 0;
>   }
>   
>   static int vhost_vdpa_set_log_base(struct vhost_dev *dev, uint64_t base,