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Subject: Re: [PATCH V4 5/5] vdpasim: vDPA device simulator
From:   Jason Wang <jasowang@redhat.com>
To:     Jason Gunthorpe <jgg@mellanox.com>
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Date:   Wed, 26 Feb 2020 14:12:26 +0800
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On 2020/2/21 =E4=B8=8B=E5=8D=883:57, Jason Wang wrote:
>
> On 2020/2/20 =E4=B8=8B=E5=8D=8811:12, Jason Gunthorpe wrote:
>> On Thu, Feb 20, 2020 at 02:11:41PM +0800, Jason Wang wrote:
>>> +static void vdpasim_device_release(struct device *dev)
>>> +{
>>> +=C2=A0=C2=A0=C2=A0 struct vdpasim *vdpasim =3D dev_to_sim(dev);
>>> +
>>> +=C2=A0=C2=A0=C2=A0 cancel_work_sync(&vdpasim->work);
>>> +=C2=A0=C2=A0=C2=A0 kfree(vdpasim->buffer);
>>> +=C2=A0=C2=A0=C2=A0 vhost_iotlb_free(vdpasim->iommu);
>>> +=C2=A0=C2=A0=C2=A0 kfree(vdpasim);
>>> +}
>>> +
>>> +static struct vdpasim *vdpasim_create(void)
>>> +{
>>> +=C2=A0=C2=A0=C2=A0 struct virtio_net_config *config;
>>> +=C2=A0=C2=A0=C2=A0 struct vhost_iotlb *iommu;
>>> +=C2=A0=C2=A0=C2=A0 struct vdpasim *vdpasim;
>>> +=C2=A0=C2=A0=C2=A0 struct device *dev;
>>> +=C2=A0=C2=A0=C2=A0 void *buffer;
>>> +=C2=A0=C2=A0=C2=A0 int ret =3D -ENOMEM;
>>> +
>>> +=C2=A0=C2=A0=C2=A0 iommu =3D vhost_iotlb_alloc(2048, 0);
>>> +=C2=A0=C2=A0=C2=A0 if (!iommu)
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 goto err;
>>> +
>>> +=C2=A0=C2=A0=C2=A0 buffer =3D kmalloc(PAGE_SIZE, GFP_KERNEL);
>>> +=C2=A0=C2=A0=C2=A0 if (!buffer)
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 goto err_buffer;
>>> +
>>> +=C2=A0=C2=A0=C2=A0 vdpasim =3D kzalloc(sizeof(*vdpasim), GFP_KERNEL)=
;
>>> +=C2=A0=C2=A0=C2=A0 if (!vdpasim)
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 goto err_alloc;
>>> +
>>> +=C2=A0=C2=A0=C2=A0 vdpasim->buffer =3D buffer;
>>> +=C2=A0=C2=A0=C2=A0 vdpasim->iommu =3D iommu;
>>> +
>>> +=C2=A0=C2=A0=C2=A0 config =3D &vdpasim->config;
>>> +=C2=A0=C2=A0=C2=A0 config->mtu =3D 1500;
>>> +=C2=A0=C2=A0=C2=A0 config->status =3D VIRTIO_NET_S_LINK_UP;
>>> +=C2=A0=C2=A0=C2=A0 eth_random_addr(config->mac);
>>> +
>>> +=C2=A0=C2=A0=C2=A0 INIT_WORK(&vdpasim->work, vdpasim_work);
>>> +=C2=A0=C2=A0=C2=A0 spin_lock_init(&vdpasim->lock);
>>> +
>>> +=C2=A0=C2=A0=C2=A0 vringh_set_iotlb(&vdpasim->vqs[0].vring, vdpasim-=
>iommu);
>>> +=C2=A0=C2=A0=C2=A0 vringh_set_iotlb(&vdpasim->vqs[1].vring, vdpasim-=
>iommu);
>>> +
>>> +=C2=A0=C2=A0=C2=A0 dev =3D &vdpasim->dev;
>>> +=C2=A0=C2=A0=C2=A0 dev->release =3D vdpasim_device_release;
>>> +=C2=A0=C2=A0=C2=A0 dev->coherent_dma_mask =3D DMA_BIT_MASK(64);
>>> +=C2=A0=C2=A0=C2=A0 set_dma_ops(dev, &vdpasim_dma_ops);
>>> +=C2=A0=C2=A0=C2=A0 dev_set_name(dev, "%s", VDPASIM_NAME);
>>> +
>>> +=C2=A0=C2=A0=C2=A0 ret =3D device_register(&vdpasim->dev);
>>> +=C2=A0=C2=A0=C2=A0 if (ret)
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 goto err_init;
>> It is a bit weird to be creating this dummy parent, couldn't this be
>> done by just passing a NULL parent to vdpa_alloc_device, doing
>> set_dma_ops() on the vdpasim->vdpa->dev and setting dma_device to
>> vdpasim->vdpa->dev ?
>
>
> I think it works.


Rethink about this, since most hardware vDPA driver will have a parent=20
and will use it to find the parent structure e.g

dev_get_drvdata(vdpa->dev->parent)

So I keep this dummy parent in V5.

Thanks