Re: [PATCH] virtio_balloon: fix up endian-ness for free cmd id

[Wei Wang]

On 07/28/2020 12:03 AM, Michael S. Tsirkin wrote:
> free cmd id is read using virtio endian, spec says all fields
> in balloon are LE. Fix it up.
>
> Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
>   drivers/virtio/virtio_balloon.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 774deb65a9bb..798ec304fe3e 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -578,10 +578,14 @@ static int init_vqs(struct virtio_balloon *vb)
>   static u32 virtio_balloon_cmd_id_received(struct virtio_balloon *vb)
>   {
>   	if (test_and_clear_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
> -			       &vb->config_read_bitmap))
> +			       &vb->config_read_bitmap)) {
>   		virtio_cread(vb->vdev, struct virtio_balloon_config,
>   			     free_page_hint_cmd_id,
>   			     &vb->cmd_id_received_cache);
> +		/* Legacy balloon config space is LE, unlike all other devices. */
> +		if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1))
> +			vb->cmd_id_received_cache = le32_to_cpu((__force __le32)vb->cmd_id_received_cache);
Seems it exceeds 80 character length.

Reviewed-by: Wei Wang <wei.w.wang@xxxxxxxxx>

Best,
Wei