Re: [dpdk-dev] [PATCH] net/virtio: fix kernel set features for multi-queue devices

[Thierry Herbelot <thierry.herbelot@6wind.com>]

Hello Maxime,

On 6/1/21 9:51 AM, Maxime Coquelin wrote:
> 
> 
> On 5/28/21 3:20 PM, Thierry Herbelot wrote:
>> Restore the original code, where VHOST_SET_FEATURES is applied to
>> all vhostfds of the device.
>>
>> Fixes: cc0151b34dee ("net/virtio: add virtio-user features ops")
>> Cc: stable@dpdk.org
>> Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
>> Cc: Chenbo Xia <chenbo.xia@intel.com>
>>
>> Signed-off-by: Thierry Herbelot <thierry.herbelot@6wind.com>
>> ---
>>   drivers/net/virtio/virtio_user/vhost_kernel.c | 13 ++++++++++++-
>>   1 file changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/virtio/virtio_user/vhost_kernel.c b/drivers/net/virtio/virtio_user/vhost_kernel.c
>> index ad46f10a9300..d65f89e1fc16 100644
>> --- a/drivers/net/virtio/virtio_user/vhost_kernel.c
>> +++ b/drivers/net/virtio/virtio_user/vhost_kernel.c
>> @@ -158,6 +158,8 @@ static int
>>   vhost_kernel_set_features(struct virtio_user_dev *dev, uint64_t features)
>>   {
>>   	struct vhost_kernel_data *data = dev->backend_data;
>> +	uint32_t i;
>> +	int ret;
>>   
>>   	/* We don't need memory protection here */
>>   	features &= ~(1ULL << VIRTIO_F_IOMMU_PLATFORM);
>> @@ -166,7 +168,16 @@ vhost_kernel_set_features(struct virtio_user_dev *dev, uint64_t features)
>>   	features &= ~VHOST_KERNEL_HOST_OFFLOADS_MASK;
>>   	features &= ~(1ULL << VIRTIO_NET_F_MQ);
>>   
>> -	return vhost_kernel_ioctl(data->vhostfds[0], VHOST_SET_FEATURES, &features);
>> +	for (i = 0; i < dev->max_queue_pairs; ++i) {
>> +		if (data->vhostfds[i] < 0)
>> +			continue;
>> +
>> +		ret = vhost_kernel_ioctl(data->vhostfds[i], VHOST_SET_FEATURES, &features);
>> +		if (ret < 0)
>> +			return ret;
>> +	}
>> +
>> +	return 0;
>>   }
>>   
>>   static int
>>
> 
> Thanks for fixing it, it should be the last one...
> 
> Except GET_FEATURES that was also queried for every queue pair, but I
> don't think it makes sense to query it and just drop the value read.
> What do you think?

Indeed, GET_FEATURES returns a single value: let's assume the value for 
the first queue pair is the right one.

	Thierry

> 
> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> 
> Thanks,
> Maxime
> 

-- 
Thierry Herbelot
Senior Software Engineer
Tel: +33 1 39 30 92 61
http://www.6wind.com/

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