linux-kernel - Re: [PATCH] vdp/mlx5: Fix setting the correct dma_device

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Date:   Mon, 7 Jun 2021 10:30:42 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Leon Romanovsky <leon@...nel.org>
Cc:     Eli Cohen <elic@...dia.com>, mst@...hat.com,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] vdp/mlx5: Fix setting the correct dma_device

在 2021/6/4 下午11:57, Leon Romanovsky 写道:
> On Fri, Jun 04, 2021 at 10:35:59AM +0800, Jason Wang wrote:
>> 在 2021/6/3 下午7:22, Eli Cohen 写道:
>>> Before SF support was introduced, the DMA device was equal to
>>> mdev->device which was in essence equal to pdev->dev;
>>> With SF introduction this is no longer true. It has already been
>>> handled for vhost_vdpa since the reference to the dma device can from
>>> within mlx5_vdpa. With virtio_vdpa this broke. To fix this we set the
>>> real dma device when initializing the device.
>>>
>>> Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
>>
>> Note sure this is correct, according to the commit log it should be the
>> patch that introduces the SF or aux bus support for vDPA.
> Where did you see that?
>
> git log -p drivers/vdpa/mlx5/net/mlx5_vnet.c
>
> ...
> +       mvdev->vdev.dma_dev = mdev->device;
> +       err = mlx5_vdpa_alloc_resources(&ndev->mvdev);
> ...
>   comes from commit 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")

If I read the commit log and code correctly:

"

With SF introduction this is no longer true.

"

It works before SF is introduced.

Thanks

>
> Thanks
>
>>
>>> Signed-off-by: Eli Cohen <elic@...dia.com>
>>
>> Patch looks correct.
>>
>> Thanks
>>
>>
>>> ---
>>>    drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
>>> index bc33f2c523d3..a4ff158181e0 100644
>>> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
>>> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
>>> @@ -2046,7 +2046,7 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name)
>>>    	if (err)
>>>    		goto err_mtu;
>>> -	mvdev->vdev.dma_dev = mdev->device;
>>> +	mvdev->vdev.dma_dev = &mdev->pdev->dev;
>>>    	err = mlx5_vdpa_alloc_resources(&ndev->mvdev);
>>>    	if (err)
>>>    		goto err_mtu;
>> _______________________________________________
>> Virtualization mailing list
>> Virtualization@...ts.linux-foundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/virtualization

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