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Re: [Qemu-devel] [PATCH 2/2] virtio: Set status early in VirtIODevice pa
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] virtio: Set status early in VirtIODevice parent object |
Date: |
Wed, 27 Jun 2018 11:21:42 +0100 |
User-agent: |
Mutt/1.10.0 (2018-05-17) |
On Wed, Jun 27, 2018 at 01:52:48PM +0530, Pankaj Gupta wrote:
> To process pending requests for driver status 'VIRTIO_CONFIG_S_DRIVER_OK',
> virtio-rng 'set_status' calls 'is_guest_ready' function. This checks if
> virtqueue is ready and status is set to 'VIRTIO_CONFIG_S_DRIVER_OK'.
>
> This call is made before new status is updated in VirtIODevice parent object
> and calling function uses old status value.
>
> Signed-off-by: Pankaj Gupta <address@hidden>
> ---
> hw/virtio/virtio.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index d4e4d98b59..37dc59a686 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -1154,10 +1154,11 @@ int virtio_set_status(VirtIODevice *vdev, uint8_t val)
> }
> }
> }
> + vdev->status = val;
> +
> if (k->set_status) {
> k->set_status(vdev, val);
> }
> - vdev->status = val;
This breaks existing ->set_status() callbacks that rely on vdev->status
containing the old value. Have you audited them?
For example, virtio_net_set_status -> virtio_net_vnet_endian_status uses
vdev->status!
It may be easier to modify virtio-rng.c so that the old status value
isn't used.
Stefan
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