Re: [dpdk-dev] [PATCH v1 1/4] vhost: support host notifier queue configuration

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

On 6/21/20 8:26 AM, Matan Azrad wrote:
> Hi Maxime
> 
> From: Maxime Coquelin:
>> On 6/19/20 3:28 PM, Matan Azrad wrote:
>>>
>>>
>>> From: Maxime Coquelin:
>>>> On 6/18/20 6:28 PM, Matan Azrad wrote:
>>>>> As an arrangement to per queue operations in the vDPA device it is
>>>>> needed to change the next experimental API:
>>>>>
>>>>> The API ``rte_vhost_host_notifier_ctrl`` was changed to be per queue
>>>>> instead of per device.
>>>>>
>>>>> A `qid` parameter was added to the API arguments list.
>>>>>
>>>>> Setting the parameter to the value VHOST_QUEUE_ALL will configure
>>>>> the host notifier to all the device queues as done before this patch.
>>>>>
>>>>> Signed-off-by: Matan Azrad <matan@mellanox.com>
>>>>> ---
>>>>>  doc/guides/rel_notes/release_20_08.rst |  2 ++
>>>>>  drivers/vdpa/ifc/ifcvf_vdpa.c          |  6 +++---
>>>>>  drivers/vdpa/mlx5/mlx5_vdpa.c          |  5 +++--
>>>>>  lib/librte_vhost/rte_vdpa.h            |  8 ++++++--
>>>>>  lib/librte_vhost/rte_vhost.h           |  2 ++
>>>>>  lib/librte_vhost/vhost.h               |  3 ---
>>>>>  lib/librte_vhost/vhost_user.c          | 18 ++++++++++++++----
>>>>>  7 files changed, 30 insertions(+), 14 deletions(-)
>>>>>
>>>>> diff --git a/doc/guides/rel_notes/release_20_08.rst
>>>>> b/doc/guides/rel_notes/release_20_08.rst
>>>>> index ba16d3b..9732959 100644
>>>>> --- a/doc/guides/rel_notes/release_20_08.rst
>>>>> +++ b/doc/guides/rel_notes/release_20_08.rst
>>>>> @@ -111,6 +111,8 @@ API Changes
>>>>>     Also, make sure to start the actual text at the margin.
>>>>>
>>>>
>> =========================================================
>>>>>
>>>>> +* vhost: The API of ``rte_vhost_host_notifier_ctrl`` was changed to
>>>>> +be per
>>>>> +  queue and not per device, a qid parameter was added to the
>>>>> +arguments
>>>> list.
>>>>>
>>>>>  ABI Changes
>>>>>  -----------
>>>>> diff --git a/drivers/vdpa/ifc/ifcvf_vdpa.c
>>>>> b/drivers/vdpa/ifc/ifcvf_vdpa.c index ec97178..336837a 100644
>>>>> --- a/drivers/vdpa/ifc/ifcvf_vdpa.c
>>>>> +++ b/drivers/vdpa/ifc/ifcvf_vdpa.c
>>>>> @@ -839,7 +839,7 @@ struct internal_list {
>>>>>  	vdpa_ifcvf_stop(internal);
>>>>>  	vdpa_disable_vfio_intr(internal);
>>>>>
>>>>> -	ret = rte_vhost_host_notifier_ctrl(vid, false);
>>>>> +	ret = rte_vhost_host_notifier_ctrl(vid, VHOST_QUEUE_ALL, false);
>>>>>  	if (ret && ret != -ENOTSUP)
>>>>>  		goto error;
>>>>>
>>>>> @@ -858,7 +858,7 @@ struct internal_list {
>>>>>  	if (ret)
>>>>>  		goto stop_vf;
>>>>>
>>>>> -	rte_vhost_host_notifier_ctrl(vid, true);
>>>>> +	rte_vhost_host_notifier_ctrl(vid, VHOST_QUEUE_ALL, true);
>>>>>
>>>>>  	internal->sw_fallback_running = true;
>>>>>
>>>>> @@ -893,7 +893,7 @@ struct internal_list {
>>>>>  	rte_atomic32_set(&internal->dev_attached, 1);
>>>>>  	update_datapath(internal);
>>>>>
>>>>> -	if (rte_vhost_host_notifier_ctrl(vid, true) != 0)
>>>>> +	if (rte_vhost_host_notifier_ctrl(vid, VHOST_QUEUE_ALL, true) != 0)
>>>>>  		DRV_LOG(NOTICE, "vDPA (%d): software relay is used.", did);
>>>>>
>>>>>  	return 0;
>>>>> diff --git a/drivers/vdpa/mlx5/mlx5_vdpa.c
>>>>> b/drivers/vdpa/mlx5/mlx5_vdpa.c index 9e758b6..8ea1300 100644
>>>>> --- a/drivers/vdpa/mlx5/mlx5_vdpa.c
>>>>> +++ b/drivers/vdpa/mlx5/mlx5_vdpa.c
>>>>> @@ -147,7 +147,8 @@
>>>>>  	int ret;
>>>>>
>>>>>  	if (priv->direct_notifier) {
>>>>> -		ret = rte_vhost_host_notifier_ctrl(priv->vid, false);
>>>>> +		ret = rte_vhost_host_notifier_ctrl(priv->vid,
>>>> VHOST_QUEUE_ALL,
>>>>> +						   false);
>>>>>  		if (ret != 0) {
>>>>>  			DRV_LOG(INFO, "Direct HW notifier FD cannot be "
>>>>>  				"destroyed for device %d: %d.", priv->vid,
>>>> ret); @@ -155,7 +156,7
>>>>> @@
>>>>>  		}
>>>>>  		priv->direct_notifier = 0;
>>>>>  	}
>>>>> -	ret = rte_vhost_host_notifier_ctrl(priv->vid, true);
>>>>> +	ret = rte_vhost_host_notifier_ctrl(priv->vid, VHOST_QUEUE_ALL,
>>>>> +true);
>>>>>  	if (ret != 0)
>>>>>  		DRV_LOG(INFO, "Direct HW notifier FD cannot be configured
>>>> for"
>>>>>  			" device %d: %d.", priv->vid, ret); diff --git
>>>>> a/lib/librte_vhost/rte_vdpa.h b/lib/librte_vhost/rte_vdpa.h index
>>>>> ecb3d91..2db536c 100644
>>>>> --- a/lib/librte_vhost/rte_vdpa.h
>>>>> +++ b/lib/librte_vhost/rte_vdpa.h
>>>>> @@ -202,22 +202,26 @@ struct rte_vdpa_device *  int
>>>>> rte_vdpa_get_device_num(void);
>>>>>
>>>>> +#define VHOST_QUEUE_ALL VHOST_MAX_VRING
>>>>> +
>>>>>  /**
>>>>>   * @warning
>>>>>   * @b EXPERIMENTAL: this API may change without prior notice
>>>>>   *
>>>>> - * Enable/Disable host notifier mapping for a vdpa port.
>>>>> + * Enable/Disable host notifier mapping for a vdpa queue.
>>>>>   *
>>>>>   * @param vid
>>>>>   *  vhost device id
>>>>>   * @param enable
>>>>>   *  true for host notifier map, false for host notifier unmap
>>>>> + * @param qid
>>>>> + *  vhost queue id, VHOST_QUEUE_ALL to configure all the device
>>>>> + queues
>>>> I would prefer two APIs that passing a special ID that means all queues:
>>>>
>>>> rte_vhost_host_notifier_ctrl(int vid, uint16_t qid, bool enable);
>>>> rte_vhost_host_notifier_ctrl_all(int vid, bool enable);
>>>>
>>>> I think it is clearer for the user of the API.
>>>> Or if you think an extra API is overkill, just let the driver loop on
>>>> all the queues.
>>>
>>> We have a lot of options here with pros and cons.
>>> I took the rte_eth_dev_callback_register style.
>>
>> Ok, I didn't looked at this code.
>>
>>> It is less intrusive with minimum code change.
>>>
>>> I'm not sure what is the clearest option but the current suggestion is
>>> well defined and allows to configure all the queues too.
>>>
>>> Let me know what you prefer....
>>
>> I personally don't like the style, but I can live with it if you prefer doing it like
>> that.
>>
>> If you do it that way, you will have to rename VHOST_QUEUE_ALL to
>> RTE_VHOST_QUEUE_ALL, VHOST_MAX_VRING  to RTE_VHOST_MAX_VRING
>> and VHOST_MAX_QUEUE_PAIRS to RTE_VHOST_MAX_QUEUE_PAIRS as it
>> will become part of the ABI.
>>
>> Not that it also means that we won't be able to increase the maximum
>> number of rings without breaking the ABI.
> 
> What's about defining RTE_VHOST_QUEUE_ALL as UINT16_MAX?

I am not fan, but it is better than basing it on VHOST_MAX_QUEUE_PAIRS.

>>>>>   * @return
>>>>>   *  0 on success, -1 on failure
>>>>>   */
>>>>>  __rte_experimental
>>>>>  int
>>>>> -rte_vhost_host_notifier_ctrl(int vid, bool enable);
>>>>> +rte_vhost_host_notifier_ctrl(int vid, uint16_t qid, bool enable);
>>>>>
>>>>>  /**
>>>
>