Re: [PATCH] hw/virtio: Have virtio_bus_get_vdev_bad_features() return 64-bit value

[Michael S. Tsirkin]

On Thu, May 20, 2021 at 12:28:22PM +0200, Philippe Mathieu-Daudé wrote:
> In commit 019a3edbb25 ("virtio: make features 64bit wide") we
> increased the 'features' field to 64-bit, but forgot to update
> the virtio_bus_get_vdev_bad_features() helper. The 'bad features'
> are truncated to 32-bit. The virtio_net_bad_features() handler
> from the virtio-net devices is potentially affected.

I'm fine with increasing it for consistency, but bad features
are all legacy things aren't they? So there isn't a functional
issue ... or did I miss anything?

> 
> Have the virtio_bus_get_vdev_bad_features() helper return the
> full 64-bit value.
> 
> Cc: qemu-stable@nongnu.org
> Fixes: 019a3edbb25 ("virtio: make features 64bit wide")
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  include/hw/virtio/virtio-bus.h | 2 +-
>  hw/virtio/virtio-bus.c         | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/hw/virtio/virtio-bus.h b/include/hw/virtio/virtio-bus.h
> index ef8abe49c5a..f9955ff577a 100644
> --- a/include/hw/virtio/virtio-bus.h
> +++ b/include/hw/virtio/virtio-bus.h
> @@ -122,7 +122,7 @@ uint16_t virtio_bus_get_vdev_id(VirtioBusState *bus);
>  /* Get the config_len field of the plugged device. */
>  size_t virtio_bus_get_vdev_config_len(VirtioBusState *bus);
>  /* Get bad features of the plugged device. */
> -uint32_t virtio_bus_get_vdev_bad_features(VirtioBusState *bus);
> +uint64_t virtio_bus_get_vdev_bad_features(VirtioBusState *bus);
>  /* Get config of the plugged device. */
>  void virtio_bus_get_vdev_config(VirtioBusState *bus, uint8_t *config);
>  /* Set config of the plugged device. */
> diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c
> index 859978d2487..25a2b68a234 100644
> --- a/hw/virtio/virtio-bus.c
> +++ b/hw/virtio/virtio-bus.c
> @@ -134,7 +134,7 @@ size_t virtio_bus_get_vdev_config_len(VirtioBusState *bus)
>  }
>  
>  /* Get bad features of the plugged device. */
> -uint32_t virtio_bus_get_vdev_bad_features(VirtioBusState *bus)
> +uint64_t virtio_bus_get_vdev_bad_features(VirtioBusState *bus)
>  {
>      VirtIODevice *vdev = virtio_bus_get_device(bus);
>      VirtioDeviceClass *k;
> -- 
> 2.26.3