[RFC 15/27] vhost: add API to set max queue pairs

[Maxime Coquelin]

On 5/5/23 07:07, Xia, Chenbo wrote:
> Hi Maxime,
> 
>> -----Original Message-----
>> From: Maxime Coquelin <maxime.coquelin at redhat.com>
>> Sent: Friday, March 31, 2023 11:43 PM
>> To: dev at dpdk.org; david.marchand at redhat.com; Xia, Chenbo
>> <chenbo.xia at intel.com>; mkp at redhat.com; fbl at redhat.com;
>> jasowang at redhat.com; Liang, Cunming <cunming.liang at intel.com>; Xie, Yongji
>> <xieyongji at bytedance.com>; echaudro at redhat.com; eperezma at redhat.com;
>> amorenoz at redhat.com
>> Cc: Maxime Coquelin <maxime.coquelin at redhat.com>
>> Subject: [RFC 15/27] vhost: add API to set max queue pairs
>>
>> This patch introduces a new rte_vhost_driver_set_max_queues
>> API as preliminary work for multiqueue support with VDUSE.
>>
>> Indeed, with VDUSE we need to pre-allocate the vrings at
>> device creation time, so we need such API not to allocate
>> the 128 queue pairs supported by the Vhost library.
>>
>> Calling the API is optional, 128 queue pairs remaining the
>> default.
>>
>> Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
>> ---
>>   doc/guides/prog_guide/vhost_lib.rst |  4 ++++
>>   lib/vhost/rte_vhost.h               | 17 ++++++++++++++
>>   lib/vhost/socket.c                  | 36 +++++++++++++++++++++++++++--
>>   lib/vhost/version.map               |  3 +++
>>   4 files changed, 58 insertions(+), 2 deletions(-)
> 
> Also add changes in release notes? Btw: somewhere we should also mention vduse
> support is added in release notes.
Correct, I need to update the release note in v2.

Thanks,
Maxime

> Thanks,
> Chenbo
> 
>>
>> diff --git a/doc/guides/prog_guide/vhost_lib.rst
>> b/doc/guides/prog_guide/vhost_lib.rst
>> index e8bb8c9b7b..cd4b109139 100644
>> --- a/doc/guides/prog_guide/vhost_lib.rst
>> +++ b/doc/guides/prog_guide/vhost_lib.rst
>> @@ -334,6 +334,10 @@ The following is an overview of some key Vhost API
>> functions:
>>     Clean DMA vChannel finished to use. After this function is called,
>>     the specified DMA vChannel should no longer be used by the Vhost
>> library.
>>
>> +* ``rte_vhost_driver_set_max_queue_num(path, max_queue_pairs)``
>> +
>> +  Set the maximum number of queue pairs supported by the device.
>> +
>>   Vhost-user Implementations
>>   --------------------------
>>
>> diff --git a/lib/vhost/rte_vhost.h b/lib/vhost/rte_vhost.h
>> index 58a5d4be92..44cbfcb469 100644
>> --- a/lib/vhost/rte_vhost.h
>> +++ b/lib/vhost/rte_vhost.h
>> @@ -588,6 +588,23 @@ rte_vhost_driver_get_protocol_features(const char
>> *path,
>>   int
>>   rte_vhost_driver_get_queue_num(const char *path, uint32_t *queue_num);
>>
>> +/**
>> + * @warning
>> + * @b EXPERIMENTAL: this API may change, or be removed, without prior
>> notice.
>> + *
>> + * Set the maximum number of queue pairs supported by the device.
>> + *
>> + * @param path
>> + *  The vhost-user socket file path
>> + * @param max_queue_pairs
>> + *  The maximum number of queue pairs
>> + * @return
>> + *  0 on success, -1 on failure
>> + */
>> +__rte_experimental
>> +int
>> +rte_vhost_driver_set_max_queue_num(const char *path, uint32_t
>> max_queue_pairs);
>> +
>>   /**
>>    * Get the feature bits after negotiation
>>    *
>> diff --git a/lib/vhost/socket.c b/lib/vhost/socket.c
>> index ba54263824..e95c3ffeac 100644
>> --- a/lib/vhost/socket.c
>> +++ b/lib/vhost/socket.c
>> @@ -56,6 +56,8 @@ struct vhost_user_socket {
>>
>>   	uint64_t protocol_features;
>>
>> +	uint32_t max_queue_pairs;
>> +
>>   	struct rte_vdpa_device *vdpa_dev;
>>
>>   	struct rte_vhost_device_ops const *notify_ops;
>> @@ -821,7 +823,7 @@ rte_vhost_driver_get_queue_num(const char *path,
>> uint32_t *queue_num)
>>
>>   	vdpa_dev = vsocket->vdpa_dev;
>>   	if (!vdpa_dev) {
>> -		*queue_num = VHOST_MAX_QUEUE_PAIRS;
>> +		*queue_num = vsocket->max_queue_pairs;
>>   		goto unlock_exit;
>>   	}
>>
>> @@ -831,7 +833,36 @@ rte_vhost_driver_get_queue_num(const char *path,
>> uint32_t *queue_num)
>>   		goto unlock_exit;
>>   	}
>>
>> -	*queue_num = RTE_MIN((uint32_t)VHOST_MAX_QUEUE_PAIRS,
>> vdpa_queue_num);
>> +	*queue_num = RTE_MIN(vsocket->max_queue_pairs, vdpa_queue_num);
>> +
>> +unlock_exit:
>> +	pthread_mutex_unlock(&vhost_user.mutex);
>> +	return ret;
>> +}
>> +
>> +int
>> +rte_vhost_driver_set_max_queue_num(const char *path, uint32_t
>> max_queue_pairs)
>> +{
>> +	struct vhost_user_socket *vsocket;
>> +	int ret = 0;
>> +
>> +	VHOST_LOG_CONFIG(path, INFO, "Setting max queue pairs to %u\n",
>> max_queue_pairs);
>> +
>> +	if (max_queue_pairs > VHOST_MAX_QUEUE_PAIRS) {
>> +		VHOST_LOG_CONFIG(path, ERR, "Library only supports up to %u
>> queue pairs\n",
>> +				VHOST_MAX_QUEUE_PAIRS);
>> +		return -1;
>> +	}
>> +
>> +	pthread_mutex_lock(&vhost_user.mutex);
>> +	vsocket = find_vhost_user_socket(path);
>> +	if (!vsocket) {
>> +		VHOST_LOG_CONFIG(path, ERR, "socket file is not registered
>> yet.\n");
>> +		ret = -1;
>> +		goto unlock_exit;
>> +	}
>> +
>> +	vsocket->max_queue_pairs = max_queue_pairs;
>>
>>   unlock_exit:
>>   	pthread_mutex_unlock(&vhost_user.mutex);
>> @@ -890,6 +921,7 @@ rte_vhost_driver_register(const char *path, uint64_t
>> flags)
>>   		goto out_free;
>>   	}
>>   	vsocket->vdpa_dev = NULL;
>> +	vsocket->max_queue_pairs = VHOST_MAX_QUEUE_PAIRS;
>>   	vsocket->extbuf = flags & RTE_VHOST_USER_EXTBUF_SUPPORT;
>>   	vsocket->linearbuf = flags & RTE_VHOST_USER_LINEARBUF_SUPPORT;
>>   	vsocket->async_copy = flags & RTE_VHOST_USER_ASYNC_COPY;
>> diff --git a/lib/vhost/version.map b/lib/vhost/version.map
>> index d322a4a888..dffb126aa8 100644
>> --- a/lib/vhost/version.map
>> +++ b/lib/vhost/version.map
>> @@ -98,6 +98,9 @@ EXPERIMENTAL {
>>   	# added in 22.11
>>   	rte_vhost_async_dma_unconfigure;
>>   	rte_vhost_vring_call_nonblock;
>> +
>> +	# added in 23.07
>> +	rte_vhost_driver_set_max_queue_num;
>>   };
>>
>>   INTERNAL {
>> --
>> 2.39.2
>