Re: [dpdk-dev] [PATCH 2/2] vhost: support requests only handled by external backend

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 3/12/19 5:14 PM, Ilya Maximets wrote:
> On 12.03.2019 17:54, Maxime Coquelin wrote:
>> External backends may have specific requests to handle, and so
>> we don't want the vhost-user lib to handle these requests as
>> errors.
>>
>> This patch also changes the experimental API by introducing
>> RTE_VHOST_MSG_RESULT_NOT_HANDLED so that vhost-user lib
>> can report an error if a message is handled neither by
>> the vhost-user library nor by the external backend.
>>
>> The logic changes a bit so that if the callback returns
>> with ERR, OK or REPLY, it is considered the message
>> is handled by the external backend so it won't be
>> handled by the vhost-user library.
>> It is still possible for an external backend to listen
>> to requests that have to be handled by the vhost-user
>> library like SET_MEM_TABLE, but the callback have to
>> return NOT_HANDLED in that case.
>>
>> Vhost-crypto backend is ialso adapted to this API change.
>>
>> Suggested-by: Ilya Maximets <i.maximets@samsung.com>
>> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>> Tested-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
>> ---
>>   lib/librte_vhost/rte_vhost.h    | 16 +++++--
>>   lib/librte_vhost/vhost_crypto.c | 10 +++-
>>   lib/librte_vhost/vhost_user.c   | 82 +++++++++++++++++++++------------
>>   3 files changed, 71 insertions(+), 37 deletions(-)
>>
>> diff --git a/lib/librte_vhost/rte_vhost.h b/lib/librte_vhost/rte_vhost.h
>> index c9c392975..b1c5a0908 100644
>> --- a/lib/librte_vhost/rte_vhost.h
>> +++ b/lib/librte_vhost/rte_vhost.h
>> @@ -121,6 +121,8 @@ enum rte_vhost_msg_result {
>>   	RTE_VHOST_MSG_RESULT_OK =  0,
>>   	/* Message handling successful and reply prepared */
>>   	RTE_VHOST_MSG_RESULT_REPLY =  1,
>> +	/* Message not handled */
>> +	RTE_VHOST_MSG_RESULT_NOT_HANDLED,
>>   };
>>   
>>   /**
>> @@ -135,11 +137,13 @@ enum rte_vhost_msg_result {
>>    *  If the handler requires skipping the master message handling, this variable
>>    *  shall be written 1, otherwise 0.
> 
> Above statement should be updated because 'skip_master' removed.

Right.

> BTW, maybe it's better to squash these two typedef's as they are
> equal now? Comment parts that differs could be moved to the definition
> of the 'struct rte_vhost_user_extern_ops'.

Good idea, doing it now.

>>    * @return
>> - *  VH_RESULT_OK on success, VH_RESULT_REPLY on success with reply,
>> - *  VH_RESULT_ERR on failure
>> + *  RTE_VHOST_MSG_RESULT_OK on success,
>> + *  RTE_VHOST_MSG_RESULT_REPLY on success with reply,
>> + *  RTE_VHOST_MSG_RESULT_ERR on failure,
>> + *  RTE_VHOST_MSG_RESULT_NOT_HANDLED if message was not handled.
>>    */
>>   typedef enum rte_vhost_msg_result (*rte_vhost_msg_pre_handle)(int vid,
>> -		void *msg, uint32_t *skip_master);
>> +		void *msg);
>>   

Thanks,
Maxime