Re: [Qemu-devel] [PATCH] virtio-net: count VIRTIO_NET_F_MAC when calculating config_len

[Jason Wang]

On 04/25/2013 02:59 PM, Michael S. Tsirkin wrote:
> On Thu, Apr 25, 2013 at 02:21:29PM +0800, Jason Wang wrote:
>> Commit 14f9b664 (hw/virtio-net.c: set config size using host features) tries 
>> to
>> calculate config size based on the host features. But it forgets the
>> VIRTIO_NET_F_MAC were always set for qemu later. This will lead a zero config
>> len for virtio-net device when both VIRTIO_NET_F_STATUS and VIRTIO_NET_F_MQ 
>> were
>> disabled form command line. Then qemu will crash when user tries to read the
>> config of virtio-net.
>>
>> Fix this by counting VIRTIO_NET_F_MAC and make sure the config at least 
>> contains
>> the mac address.
>>
>> Cc: Jesse Larrew <address@hidden>
>> Signed-off-by: Jason Wang <address@hidden>
>> ---
>>  hw/net/virtio-net.c |    3 ++-
>>  1 files changed, 2 insertions(+), 1 deletions(-)
>>
>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
>> index 70c8fce..33a70ef 100644
>> --- a/hw/net/virtio-net.c
>> +++ b/hw/net/virtio-net.c
>> @@ -1264,7 +1264,8 @@ static void 
>> virtio_net_guest_notifier_mask(VirtIODevice *vdev, int idx,
>>  
>>  void virtio_net_set_config_size(VirtIONet *n, uint32_t host_features)
>>  {
>> -    int i, config_size = 0;
>> +    /* VIRTIO_NET_F_MAC can't be disabled from qemu side */
>> +    int i, config_size = feature_sizes[0].end;
> This would be cleaner:
>       host_features |= (1 << VIRTIO_NET_F_MAC);
>
> no need for a comment then.

Sure, will send V2.
>>      for (i = 0; feature_sizes[i].flags != 0; i++) {
>>          if (host_features & feature_sizes[i].flags) {
>>              config_size = MAX(feature_sizes[i].end, config_size);
>> -- 
>> 1.7.1