netdev - Re: [PATCH V2 RESEND 2/2] vDPA/ifcvf: implement doorbell mapping for ifcvf

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Date:   Mon, 31 May 2021 15:56:06 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Zhu Lingshan <lingshan.zhu@...el.com>, mst@...hat.com
Cc:     virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        kvm@...r.kernel.org
Subject: Re: [PATCH V2 RESEND 2/2] vDPA/ifcvf: implement doorbell mapping for
 ifcvf


在 2021/5/31 下午3:33, Zhu Lingshan 写道:
> This commit implements doorbell mapping feature for ifcvf.
> This feature maps the notify page to userspace, to eliminate
> vmexit when kick a vq.
>
> Signed-off-by: Zhu Lingshan <lingshan.zhu@...el.com>
> ---
>   drivers/vdpa/ifcvf/ifcvf_main.c | 17 +++++++++++++++++
>   1 file changed, 17 insertions(+)
>
> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
> index ab0ab5cf0f6e..effb0e549135 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> @@ -413,6 +413,22 @@ static int ifcvf_vdpa_get_vq_irq(struct vdpa_device *vdpa_dev,
>   	return vf->vring[qid].irq;
>   }
>   
> +static struct vdpa_notification_area ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,
> +							       u16 idx)
> +{
> +	struct ifcvf_adapter *adapter = vdpa_to_adapter(vdpa_dev);
> +	struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
> +	struct pci_dev *pdev = adapter->pdev;
> +	struct vdpa_notification_area area;
> +
> +	area.addr = vf->vring[idx].notify_pa;
> +	area.size = PAGE_SIZE;
> +	if (area.addr % PAGE_SIZE)
> +		IFCVF_DBG(pdev, "vq %u doorbell address is not PAGE_SIZE aligned\n", idx);


Let's leave the decision to upper layer by: (see 
vp_vdpa_get_vq_notification)

area.addr = notify_pa;
area.size = notify_offset_multiplier;

Thanks


> +
> +	return area;
> +}
> +
>   /*
>    * IFCVF currently does't have on-chip IOMMU, so not
>    * implemented set_map()/dma_map()/dma_unmap()
> @@ -440,6 +456,7 @@ static const struct vdpa_config_ops ifc_vdpa_ops = {
>   	.get_config	= ifcvf_vdpa_get_config,
>   	.set_config	= ifcvf_vdpa_set_config,
>   	.set_config_cb  = ifcvf_vdpa_set_config_cb,
> +	.get_vq_notification = ifcvf_get_vq_notification,
>   };
>   
>   static int ifcvf_probe(struct pci_dev *pdev, const struct pci_device_id *id)