Re: [Qemu-devel] [PATCH V3 6/6] virtio-pci: unbreak queue_enable read

[Jason Wang]

On 11/09/2015 09:14 PM, Cornelia Huck wrote:
> On Fri,  6 Nov 2015 16:02:49 +0800
> Jason Wang <address@hidden> wrote:
>
>> Guest always get zero when reading queue_enable. This violates
>> spec. Fixing this by setting the queue_enable to true during any guest
>> writing and setting it to zero during reset.
>>
>> Cc: Michael S. Tsirkin <address@hidden>
>> Signed-off-by: Jason Wang <address@hidden>
>> ---
>>  hw/virtio/virtio-pci.c | 7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
>> index e4449da..52a9e33 100644
>> --- a/hw/virtio/virtio-pci.c
>> +++ b/hw/virtio/virtio-pci.c
>> @@ -1384,6 +1384,7 @@ static void virtio_pci_common_write(void *opaque, 
>> hwaddr addr,
>>                         proxy->vqs[vdev->queue_sel].avail[0],
>>                         ((uint64_t)proxy->vqs[vdev->queue_sel].used[1]) << 
>> 32 |
>>                         proxy->vqs[vdev->queue_sel].used[0]);
>> +        proxy->vqs[vdev->queue_sel].enabled = 1;
> Hm. Spec says that the driver MUST NOT write 0 here. 

Yes.

> Does this need a
> check?

Add warn in this case? I'm not sure, I read the spec as "writing any
value implies enabling". (And the patch itself does not conflict the spec).

>
> <Also, I think you can remove the 'TODO' comment - this should be
> handled now.>

Yes

>
>>          break;
>>      case VIRTIO_PCI_COMMON_Q_DESCLO:
>>          proxy->vqs[vdev->queue_sel].desc[0] = val;
>> @@ -1831,9 +1832,15 @@ static void virtio_pci_reset(DeviceState *qdev)
>>  {
>>      VirtIOPCIProxy *proxy = VIRTIO_PCI(qdev);
>>      VirtioBusState *bus = VIRTIO_BUS(&proxy->bus);
>> +    int i;
>> +
>>      virtio_pci_stop_ioeventfd(proxy);
>>      virtio_bus_reset(bus);
>>      msix_unuse_all_vectors(&proxy->pci_dev);
>> +
>> +    for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
>> +        proxy->vqs[i].enabled = 0;
>> +    }
>>  }
>>
>>  static Property virtio_pci_properties[] = {
> Otherwise, this looks good to me.
>
>

Thanks