Re: [PATCH v3 04/21] hw/virtio: log potentially buggy guest drivers

[Jason Wang]

在 2022/7/27 03:21, Alex Bennée 写道:
> If the guest driver attempts to use the UNUSED(30) bit it is
> potentially buggy as 6.3 Legacy Interface: Reserved Feature Bits
> states it "SHOULD NOT be negotiated". For now just log this guest
> error.
>
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>


Acked-by: Jason Wang <jasowang@redhat.com>


> ---
>   hw/virtio/virtio.c | 7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 5d607aeaa0..97a6307c0f 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -2980,6 +2980,13 @@ int virtio_set_features(VirtIODevice *vdev, uint64_t val)
>       if (vdev->status & VIRTIO_CONFIG_S_FEATURES_OK) {
>           return -EINVAL;
>       }
> +
> +    if (val & (1ull << VIRTIO_F_BAD_FEATURE)) {
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "%s: guest driver for %s has enabled UNUSED(30) feature 
> bit!\n",
> +                      __func__, vdev->name);
> +    }
> +
>       ret = virtio_set_features_nocheck(vdev, val);
>       if (virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
>           /* VIRTIO_RING_F_EVENT_IDX changes the size of the caches.  */