Re: [RFC v3 03/11] vdpa: Remove the restriction that only supports virtio-net devices

[Jason Wang <jasowang@redhat.com>]

On 2021/1/20 下午7:08, Stefano Garzarella wrote:
> On Wed, Jan 20, 2021 at 11:46:38AM +0800, Jason Wang wrote:
>>
>> On 2021/1/19 下午12:59, Xie Yongji wrote:
>>> With VDUSE, we should be able to support all kinds of virtio devices.
>>>
>>> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
>>> ---
>>>  drivers/vhost/vdpa.c | 29 +++--------------------------
>>>  1 file changed, 3 insertions(+), 26 deletions(-)
>>>
>>> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
>>> index 29ed4173f04e..448be7875b6d 100644
>>> --- a/drivers/vhost/vdpa.c
>>> +++ b/drivers/vhost/vdpa.c
>>> @@ -22,6 +22,7 @@
>>>  #include <linux/nospec.h>
>>>  #include <linux/vhost.h>
>>>  #include <linux/virtio_net.h>
>>> +#include <linux/virtio_blk.h>
>>>  #include "vhost.h"
>>> @@ -185,26 +186,6 @@ static long vhost_vdpa_set_status(struct 
>>> vhost_vdpa *v, u8 __user *statusp)
>>>      return 0;
>>>  }
>>> -static int vhost_vdpa_config_validate(struct vhost_vdpa *v,
>>> -                      struct vhost_vdpa_config *c)
>>> -{
>>> -    long size = 0;
>>> -
>>> -    switch (v->virtio_id) {
>>> -    case VIRTIO_ID_NET:
>>> -        size = sizeof(struct virtio_net_config);
>>> -        break;
>>> -    }
>>> -
>>> -    if (c->len == 0)
>>> -        return -EINVAL;
>>> -
>>> -    if (c->len > size - c->off)
>>> -        return -E2BIG;
>>> -
>>> -    return 0;
>>> -}
>>
>>
>> I think we should use a separate patch for this.
>
> For the vdpa-blk simulator I had the same issues and I'm adding a 
> .get_config_size() callback to vdpa devices.
>
> Do you think make sense or is better to remove this check in 
> vhost/vdpa, delegating the boundaries checks to get_config/set_config 
> callbacks.


A question here. How much value could we gain from get_config_size() 
consider we can let vDPA parent to validate the length in its get_config().

Thanks


>
> Thanks,
> Stefano
>