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Subject: Re: [PATCH] virtio_balloon: fix up endian-ness for free cmd id
To:     "Michael S. Tsirkin" <mst@redhat.com>, linux-kernel@vger.kernel.org
Cc:     stable@vger.kernel.org, David Hildenbrand <david@redhat.com>,
        Liang Li <liang.z.li@intel.com>,
        Wei Wang <wei.w.wang@intel.com>,
        virtualization@lists.linux-foundation.org,
        Alexander Duyck <alexander.duyck@gmail.com>
References: <20200727160310.102494-1-mst@redhat.com>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <0dceaf8c-de35-93d6-f81b-67c2fdebf5ef@redhat.com>
Date:   Wed, 29 Jul 2020 17:33:03 +0800
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On 2020/7/28 上午12:03, 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@vger.kernel.org
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>   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);
> +	}
>   
>   	return vb->cmd_id_received_cache;
>   }


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