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From: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Date: Tue, 13 May 2014 18:47:47 +0300
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Subject: Re: [Qemu-devel] [PULL] virtio: allow mapping up to max queue size
Reply-To: marcel.a@redhat.com
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, qemu-stable@nongnu.org, qemu-devel@nongnu.org, Anthony Liguori <aliguori@amazon.com>, "Dr.
	David Alan Gilbert" <dgilbert@redhat.com>

On Tue, 2014-05-13 at 18:42 +0300, Michael S. Tsirkin wrote:
> It's a loop from i < num_sg  and the array is VIRTQUEUE_MAX_SIZE - so
> it's OK if the value read is VIRTQUEUE_MAX_SIZE.
> 
> Not a big problem in practice as people don't use
> such big queues, but it's inelegant.
> 
> Reported-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  hw/virtio/virtio.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 7f4e7ec..3557c17 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -430,7 +430,7 @@ void virtqueue_map_sg(struct iovec *sg, hwaddr *addr,
>      unsigned int i;
>      hwaddr len;
>  
> -    if (num_sg >= VIRTQUEUE_MAX_SIZE) {
> +    if (num_sg > VIRTQUEUE_MAX_SIZE) {
>          error_report("virtio: map attempt out of bounds: %zd > %d",
>                       num_sg, VIRTQUEUE_MAX_SIZE);
>          exit(1);

ACK

Thanks,
Marcel