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

[Matan Azrad <matan@mellanox.com>]

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?

> >>>   * @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);
> >>>
> >>>  /**
> >