vhost: zero_copy incompatible with client mode

In server mode, virtio-user inits under the assumption that vhost-user
supports a list of features. However, this could be problematic when
in_order feature is negotiated but not supported by vhost-user when
enables dequeue_zero_copy later.

Add handling when vhost-user enables dequeue_zero_copy as client.

Signed-off-by: Xuan Ding <xuan.ding@intel.com>
---
 lib/librte_vhost/socket.c | 6 ++++++
 1 file changed, 6 insertions(+)
  

Tested-by: Yinan Wang <yinan.wang@intel.com>

> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Xuan Ding
> Sent: 2020年4月29日 11:00
> To: maxime.coquelin@redhat.com; Wang, Zhihong <zhihong.wang@intel.com>;
> Ye, Xiaolong <xiaolong.ye@intel.com>
> Cc: dev@dpdk.org; Ding, Xuan <xuan.ding@intel.com>
> Subject: [dpdk-dev] [PATCH] vhost: zero_copy incompatible with client mode
> 
> In server mode, virtio-user inits under the assumption that vhost-user supports a
> list of features. However, this could be problematic when in_order feature is
> negotiated but not supported by vhost-user when enables dequeue_zero_copy
> later.
> 
> Add handling when vhost-user enables dequeue_zero_copy as client.
> 
> Signed-off-by: Xuan Ding <xuan.ding@intel.com>
> ---
>  lib/librte_vhost/socket.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c index
> 7c8012179..bb8d0d780 100644
> --- a/lib/librte_vhost/socket.c
> +++ b/lib/librte_vhost/socket.c
> @@ -926,6 +926,12 @@ rte_vhost_driver_register(const char *path, uint64_t
> flags)
>  			ret = -1;
>  			goto out_mutex;
>  		}
> +		if (!vsocket->is_server) {
> +			VHOST_LOG_CONFIG(ERR,
> +			"error: zero copy is incompatible with vhost client
> mode\n");
> +			ret = -1;
> +			goto out_mutex;
> +		}
>  		vsocket->supported_features &= ~(1ULL <<
> VIRTIO_F_IN_ORDER);
>  		vsocket->features &= ~(1ULL << VIRTIO_F_IN_ORDER);
> 
> --
> 2.17.1
  

Hi Yinan,

On 4/29/20 10:33 AM, Wang, Yinan wrote:
> Tested-by: Yinan Wang <yinan.wang@intel.com>

Thanks for running tests on Vhost patches, that's much appreciated.

Could you provide more information on the test run?
Does it consist in reproducing the issue the patch is aiming to fix,
apply patch and check issue is fixed?
Or does it consist in running a generic Vhost/Virtio test suite?

Regards,
Maxime

>> -----Original Message-----
>> From: dev <dev-bounces@dpdk.org> On Behalf Of Xuan Ding
>> Sent: 2020年4月29日 11:00
>> To: maxime.coquelin@redhat.com; Wang, Zhihong <zhihong.wang@intel.com>;
>> Ye, Xiaolong <xiaolong.ye@intel.com>
>> Cc: dev@dpdk.org; Ding, Xuan <xuan.ding@intel.com>
>> Subject: [dpdk-dev] [PATCH] vhost: zero_copy incompatible with client mode
>>
>> In server mode, virtio-user inits under the assumption that vhost-user supports a
>> list of features. However, this could be problematic when in_order feature is
>> negotiated but not supported by vhost-user when enables dequeue_zero_copy
>> later.
>>
>> Add handling when vhost-user enables dequeue_zero_copy as client.
>>
>> Signed-off-by: Xuan Ding <xuan.ding@intel.com>
>> ---
>>  lib/librte_vhost/socket.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c index
>> 7c8012179..bb8d0d780 100644
>> --- a/lib/librte_vhost/socket.c
>> +++ b/lib/librte_vhost/socket.c
>> @@ -926,6 +926,12 @@ rte_vhost_driver_register(const char *path, uint64_t
>> flags)
>>  			ret = -1;
>>  			goto out_mutex;
>>  		}
>> +		if (!vsocket->is_server) {
>> +			VHOST_LOG_CONFIG(ERR,
>> +			"error: zero copy is incompatible with vhost client
>> mode\n");
>> +			ret = -1;
>> +			goto out_mutex;
>> +		}
>>  		vsocket->supported_features &= ~(1ULL <<
>> VIRTIO_F_IN_ORDER);
>>  		vsocket->features &= ~(1ULL << VIRTIO_F_IN_ORDER);
>>
>> --
>> 2.17.1
>
  

On 4/29/20 4:59 AM, Xuan Ding wrote:
> In server mode, virtio-user inits under the assumption that vhost-user
> supports a list of features. However, this could be problematic when
> in_order feature is negotiated but not supported by vhost-user when
> enables dequeue_zero_copy later.
> 
> Add handling when vhost-user enables dequeue_zero_copy as client.
> 
> Signed-off-by: Xuan Ding <xuan.ding@intel.com>
> ---
>  lib/librte_vhost/socket.c | 6 ++++++
>  1 file changed, 6 insertions(+)

Reiewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime
  

On 4/29/20 4:59 AM, Xuan Ding wrote:
> In server mode, virtio-user inits under the assumption that vhost-user
> supports a list of features. However, this could be problematic when
> in_order feature is negotiated but not supported by vhost-user when
> enables dequeue_zero_copy later.
> 
> Add handling when vhost-user enables dequeue_zero_copy as client.
> 
> Signed-off-by: Xuan Ding <xuan.ding@intel.com>
> ---
>  lib/librte_vhost/socket.c | 6 ++++++
>  1 file changed, 6 insertions(+)

Applied to dpdk-next-virtio/master.

Thanks,
Maxime