Re: [PATCH v4 1/2] vhost: introduce DMA vchannel unconfiguration

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

On 10/13/22 08:40, xuan.ding@intel.com wrote:
> From: Xuan Ding <xuan.ding@intel.com>
> 
> Add a new API rte_vhost_async_dma_unconfigure() to unconfigure DMA
> vchannels in vhost async data path. Lock protection are also added
> to protect DMA vchannels configuration and unconfiguration
> from concurrent calls.
> 
> Signed-off-by: Xuan Ding <xuan.ding@intel.com>
> ---
>   doc/guides/prog_guide/vhost_lib.rst    |  6 +++
>   doc/guides/rel_notes/release_22_11.rst |  4 ++
>   lib/vhost/rte_vhost_async.h            | 18 +++++++
>   lib/vhost/version.map                  |  3 ++
>   lib/vhost/vhost.c                      | 69 ++++++++++++++++++++++++--
>   5 files changed, 95 insertions(+), 5 deletions(-)
> 
> diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
> index bad4d819e1..d3cef978d0 100644
> --- a/doc/guides/prog_guide/vhost_lib.rst
> +++ b/doc/guides/prog_guide/vhost_lib.rst
> @@ -323,6 +323,12 @@ The following is an overview of some key Vhost API functions:
>     Get device type of vDPA device, such as VDPA_DEVICE_TYPE_NET,
>     VDPA_DEVICE_TYPE_BLK.
>   
> +* ``rte_vhost_async_dma_unconfigure(dma_id, vchan_id)``
> +
> +  Clean DMA vChannels finished to use. This function needs to
> +  be called after the deregistration of async DMA vchannel
> +  has been finished.
> +
>   Vhost-user Implementations
>   --------------------------
>   
> diff --git a/doc/guides/rel_notes/release_22_11.rst b/doc/guides/rel_notes/release_22_11.rst
> index 2da8bc9661..3be150122c 100644
> --- a/doc/guides/rel_notes/release_22_11.rst
> +++ b/doc/guides/rel_notes/release_22_11.rst
> @@ -236,6 +236,10 @@ New Features
>   
>        strings $dpdk_binary_or_driver | sed -n 's/^PMD_INFO_STRING= //p'
>   
> +* **Added DMA vChannel unconfiguration for async vhost.**
> +
> +  * Added support to unconfigure DMA vChannels that have been unregistered.
> +
>   
>   Removed Items
>   -------------
> diff --git a/lib/vhost/rte_vhost_async.h b/lib/vhost/rte_vhost_async.h
> index 1db2a10124..6ee4f7258d 100644
> --- a/lib/vhost/rte_vhost_async.h
> +++ b/lib/vhost/rte_vhost_async.h
> @@ -266,6 +266,24 @@ rte_vhost_async_try_dequeue_burst(int vid, uint16_t queue_id,
>   	struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count,
>   	int *nr_inflight, int16_t dma_id, uint16_t vchan_id);
>   
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change, or be removed, without prior notice.
> + *
> + * Unconfigure DMA vChannels in asynchronous data path.
> + * This function should be called after the DMA vChannel has been unregistered.
> + *
> + * @param dma_id
> + *  the identifier of DMA device
> + * @param vchan_id
> + *  the identifier of virtual DMA channel
> + * @return
> + *  0 on success, and -1 on failure
> + */
> +__rte_experimental
> +int
> +rte_vhost_async_dma_unconfigure(int16_t dma_id, uint16_t vchan_id);
> +
>   #ifdef __cplusplus
>   }
>   #endif
> diff --git a/lib/vhost/version.map b/lib/vhost/version.map
> index 7a00b65740..0b61870870 100644
> --- a/lib/vhost/version.map
> +++ b/lib/vhost/version.map
> @@ -94,6 +94,9 @@ EXPERIMENTAL {
>   	rte_vhost_async_try_dequeue_burst;
>   	rte_vhost_driver_get_vdpa_dev_type;
>   	rte_vhost_clear_queue;
> +
> +	# added in 22.11
> +	rte_vhost_async_dma_unconfigure;
>   };
>   
>   INTERNAL {
> diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
> index 8740aa2788..9fbc56229a 100644
> --- a/lib/vhost/vhost.c
> +++ b/lib/vhost/vhost.c
> @@ -23,6 +23,7 @@
>   
>   struct virtio_net *vhost_devices[RTE_MAX_VHOST_DEVICE];
>   pthread_mutex_t vhost_dev_lock = PTHREAD_MUTEX_INITIALIZER;
> +static rte_spinlock_t vhost_dma_lock = RTE_SPINLOCK_INITIALIZER;

I think a mutex would be more appropiate.

Thanks,
Maxime