Re: [dpdk-dev] [PATCH v2] vhost: avoid iotlb mempool allocation while IOMMU disabled

["Xia, Chenbo" <chenbo.xia@intel.com>]

> -----Original Message-----
> From: Wan Junjie <wanjunjie@bytedance.com>
> Sent: Tuesday, February 2, 2021 4:39 PM
> To: Xia, Chenbo <chenbo.xia@intel.com>; Maxime Coquelin
> <maxime.coquelin@redhat.com>
> Cc: dev@dpdk.org; Wan Junjie <wanjunjie@bytedance.com>; Peng He
> <hepeng.0320@bytedance.com>; Zhihong Wang <wangzhihong.wzh@bytedance.com>
> Subject: [PATCH v2] vhost: avoid iotlb mempool allocation while IOMMU disabled
> 
> If vhost device's IOMMU feature is disabled, iotlb mempool allocation
> is unnecessary.
> 
> Reported-by: Peng He <hepeng.0320@bytedance.com>
> Signed-off-by: Wan Junjie <wanjunjie@bytedance.com>
> Reviewed-by: Zhihong Wang <wangzhihong.wzh@bytedance.com>
> ---
>  lib/librte_vhost/vhost.c      | 4 ++--
>  lib/librte_vhost/vhost_user.c | 6 +++++-
>  2 files changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
> index b83cf639e..e5341ab98 100644
> --- a/lib/librte_vhost/vhost.c
> +++ b/lib/librte_vhost/vhost.c
> @@ -352,7 +352,8 @@ free_vq(struct virtio_net *dev, struct vhost_virtqueue *vq)
>  		vhost_free_async_mem(vq);
>  	}
>  	rte_free(vq->batch_copy_elems);
> -	rte_mempool_free(vq->iotlb_pool);
> +	if (vq->iotlb_pool)
> +		rte_mempool_free(vq->iotlb_pool);
>  	rte_free(vq);
>  }
> 
> @@ -556,7 +557,6 @@ init_vring_queue(struct virtio_net *dev, uint32_t
> vring_idx)
>  	vq->callfd = VIRTIO_UNINITIALIZED_EVENTFD;
>  	vq->notif_enable = VIRTIO_UNINITIALIZED_NOTIF;
> 
> -	vhost_user_iotlb_init(dev, vring_idx);
>  	/* Backends are set to -1 indicating an inactive device. */
>  	vq->backend = -1;
>  }
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 45c8ac09d..81cbb9797 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -470,6 +470,10 @@ vhost_user_set_vring_num(struct virtio_net **pdev,
>  		return RTE_VHOST_MSG_RESULT_ERR;
>  	}
> 
> +	if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)) {
> +		if (vhost_user_iotlb_init(dev, msg->payload.state.index))
> +			return RTE_VHOST_MSG_RESULT_ERR;
> +	}
>  	return RTE_VHOST_MSG_RESULT_OK;
>  }
> 
> @@ -575,7 +579,7 @@ numa_realloc(struct virtio_net *dev, int index)
>  	dev->virtqueue[index] = vq;
>  	vhost_devices[dev->vid] = dev;
> 
> -	if (old_vq != vq)
> +	if (old_vq != vq && (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)))
>  		vhost_user_iotlb_init(dev, index);
> 
>  	return dev;
> --
> 2.11.0

Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>