[PATCH RFC] virtio-pci: new config layout: using memory BAR

Peter Maydell
Wed, 29 May 2013 09:00:33 -0000

On 29 May 2013 09:24, Michael S. Tsirkin <mst at redhat.com>
wrote:
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index f4db224..fd09ea7 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -467,51 +467,70 @@ static uint64_t virtio_pci_config_common_read(void
*opaque, hwaddr addr,
>  {
>      VirtIOPCIProxy *proxy = opaque;
>      VirtIODevice *vdev = proxy->vdev;
> +    struct virtio_pci_common_cfg cfg;
>
>      uint64_t low = 0xffffffffull;
>
>      switch (addr) {
>      case offsetof(struct virtio_pci_common_cfg, device_feature_select):
> +        assert(size == sizeof cfg.device_feature_select);
>          return proxy->device_feature_select;

Asserting is definitely the wrong thing here, since the
guest can trigger it.

If you really want to use offsetof like this you're
going to need to decorate the structs with QEMU_PACKED.

thanks
-- PMM