On 10.07.20 13:31, Michael S. Tsirkin wrote:
> Page reporting features were never supported by legacy hypervisors.
> Supporting them poses a problem: should we use native endian-ness (like
> current code assumes)? Or little endian-ness like the virtio spec says?
> Rather than try to figure out, and since results of
> incorrect endian-ness are dire, let's just block this configuration.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
> drivers/virtio/virtio_balloon.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 5d4b891bf84f..b9bc03345157 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -1107,6 +1107,15 @@ static int virtballoon_restore(struct virtio_device *vdev)
>
> static int virtballoon_validate(struct virtio_device *vdev)
> {
> + /*
> + * Legacy devices never specified how modern features should behave.
> + * E.g. which endian-ness to use? Better not to assume anything.
> + */
> + if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
> + __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT);
> + __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON);
> + __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_REPORTING);
> + }
> /*
> * Inform the hypervisor that our pages are poisoned or
> * initialized. If we cannot do that then we should disable
>
Very right
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
--
Thanks,
David / dhildenb
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