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Date: Fri, 26 Jul 2013 01:34:42 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20130725223442.GB28632@redhat.com>
References: <1374759463-6351-1-git-send-email-peter.maydell@linaro.org>
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In-Reply-To: <1374759463-6351-3-git-send-email-peter.maydell@linaro.org>
Subject: Re: [Qemu-devel] [PATCH 2/2] hw/virtio/virtio-mmio: Make
 QueueNumMax read 0 for unavailable queues
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Anthony Liguori <aliguori@us.ibm.com>, KONRAD Frederic <fred.konrad@greensocs.com>, kvmarm@lists.cs.columbia.edu, qemu-devel@nongnu.org, patches@linaro.org

On Thu, Jul 25, 2013 at 02:37:43PM +0100, Peter Maydell wrote:
> The virtio-mmio spec says that QueueNumMax must read zero for queues
> which are unavailable; implement this, rather than always returning
> VIRTQUEUE_MAX_SIZE.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  hw/virtio/virtio-mmio.c |    3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c
> index 54d6679..aefb7e4 100644
> --- a/hw/virtio/virtio-mmio.c
> +++ b/hw/virtio/virtio-mmio.c
> @@ -151,6 +151,9 @@ static uint64_t virtio_mmio_read(void *opaque, hwaddr offset, unsigned size)
>          }
>          return proxy->host_features;
>      case VIRTIO_MMIO_QUEUENUMMAX:
> +        if (virtio_queue_get_num(vdev, vdev->queue_sel) == 0) {
> +            return 0;
> +        }

All other callers do:
       if (!virtio_queue_get_num(vdev, vdev->queue_sel)) {

So please make this one consistent and use the shorter form.


>          return VIRTQUEUE_MAX_SIZE;
>      case VIRTIO_MMIO_QUEUEPFN:
>          return virtio_queue_get_addr(vdev, vdev->queue_sel)
> -- 
> 1.7.9.5