[PATCH net] virtio_net: reject XDP programs using header adjustment

[PATCH net] virtio_net: reject XDP programs using header adjustment

[Jakub Kicinski]

commit 17bedab27231 ("bpf: xdp: Allow head adjustment in XDP prog")
added a new XDP helper to prepend and remove data from a frame.
Make virtio_net reject programs making use of this helper until
proper support is added.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
---
 drivers/net/virtio_net.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 08327e005ccc..db761f37783e 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1677,6 +1677,11 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
 	u16 xdp_qp = 0, curr_qp;
 	int i, err;
 
+	if (prog && prog->xdp_adjust_head) {
+		netdev_warn(dev, "Does not support bpf_xdp_adjust_head()\n");
+		return -EOPNOTSUPP;
+	}
+
 	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
 	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6)) {
 		netdev_warn(dev, "can't set XDP while host is implementing LRO, disable LRO first\n");
-- 
2.11.0

RE: [PATCH net] virtio_net: reject XDP programs using header adjustment

[Mintz, Yuval]

> commit 17bedab27231 ("bpf: xdp: Allow head adjustment in XDP prog")
> added a new XDP helper to prepend and remove data from a frame.
> Make virtio_net reject programs making use of this helper until proper
> support is added.
> 
> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

Is that how it goes until we'll add the proper infrastructure?
Am I expected to provide the same for qede?

I was under the impression that so long as this is being [early] developed
and there's no way to communicate what is and isn't supported by
a given implementation, it would simply be the user's responsibility
to make sure what he's trying is supported.

Re: [PATCH net] virtio_net: reject XDP programs using header adjustment

[Jakub Kicinski]

On Mon, Dec 19, 2016 at 3:23 PM, Mintz, Yuval <Yuval.Mintz@cavium.com> wrote:
>> commit 17bedab27231 ("bpf: xdp: Allow head adjustment in XDP prog")
>> added a new XDP helper to prepend and remove data from a frame.
>> Make virtio_net reject programs making use of this helper until proper
>> support is added.
>>
>> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
>
> Is that how it goes until we'll add the proper infrastructure?
> Am I expected to provide the same for qede?

I asked Martin to fix the existing drivers like qede but virtio's XDP
was not merged at that point.

> I was under the impression that so long as this is being [early] developed
> and there's no way to communicate what is and isn't supported by
> a given implementation, it would simply be the user's responsibility
> to make sure what he's trying is supported.

IMHO the less user has to guess the better if we're hoping for wide adoption.

Re: [PATCH net] virtio_net: reject XDP programs using header adjustment

[John Fastabend]

On 16-12-19 07:05 AM, Jakub Kicinski wrote:
> commit 17bedab27231 ("bpf: xdp: Allow head adjustment in XDP prog")
> added a new XDP helper to prepend and remove data from a frame.
> Make virtio_net reject programs making use of this helper until
> proper support is added.
> 
> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
> ---
>  drivers/net/virtio_net.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 08327e005ccc..db761f37783e 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1677,6 +1677,11 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
>  	u16 xdp_qp = 0, curr_qp;
>  	int i, err;
>  
> +	if (prog && prog->xdp_adjust_head) {
> +		netdev_warn(dev, "Does not support bpf_xdp_adjust_head()\n");
> +		return -EOPNOTSUPP;
> +	}
> +
>  	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
>  	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6)) {
>  		netdev_warn(dev, "can't set XDP while host is implementing LRO, disable LRO first\n");
> 

Acked-by: John Fastabend <john.r.fastabend@intel.com>

Thanks patch looks good. Alternatively we could push a "bug fix" to
support the adjust header feature depending on how DaveM and MST feel
about that. I don't have a strong opinion but I have the patch on my
queue it just needs some more testing. The adjust header bits were
merged in between some of the later versions of the patch which is how
this check got missed.

Thanks,
John

Re: [PATCH net] virtio_net: reject XDP programs using header adjustment

[David Miller]

From: John Fastabend <john.fastabend@gmail.com>
Date: Mon, 19 Dec 2016 09:50:57 -0800

> On 16-12-19 07:05 AM, Jakub Kicinski wrote:
>> commit 17bedab27231 ("bpf: xdp: Allow head adjustment in XDP prog")
>> added a new XDP helper to prepend and remove data from a frame.
>> Make virtio_net reject programs making use of this helper until
>> proper support is added.
>> 
>> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
>> ---
>>  drivers/net/virtio_net.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>> 
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 08327e005ccc..db761f37783e 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -1677,6 +1677,11 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
>>  	u16 xdp_qp = 0, curr_qp;
>>  	int i, err;
>>  
>> +	if (prog && prog->xdp_adjust_head) {
>> +		netdev_warn(dev, "Does not support bpf_xdp_adjust_head()\n");
>> +		return -EOPNOTSUPP;
>> +	}
>> +
>>  	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
>>  	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6)) {
>>  		netdev_warn(dev, "can't set XDP while host is implementing LRO, disable LRO first\n");
>> 
> 
> Acked-by: John Fastabend <john.r.fastabend@intel.com>
> 
> Thanks patch looks good. Alternatively we could push a "bug fix" to
> support the adjust header feature depending on how DaveM and MST feel
> about that. I don't have a strong opinion but I have the patch on my
> queue it just needs some more testing. The adjust header bits were
> merged in between some of the later versions of the patch which is how
> this check got missed.

I would like to avoid inconsistent XDP feature support amongst drivers
as much as possible.

Re: [PATCH net] virtio_net: reject XDP programs using header adjustment

[Jakub Kicinski]

On Mon, Dec 19, 2016 at 5:50 PM, John Fastabend
<john.fastabend@gmail.com> wrote:
> On 16-12-19 07:05 AM, Jakub Kicinski wrote:
>> commit 17bedab27231 ("bpf: xdp: Allow head adjustment in XDP prog")
>> added a new XDP helper to prepend and remove data from a frame.
>> Make virtio_net reject programs making use of this helper until
>> proper support is added.
>>
>> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
>> ---
>>  drivers/net/virtio_net.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 08327e005ccc..db761f37783e 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -1677,6 +1677,11 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
>>       u16 xdp_qp = 0, curr_qp;
>>       int i, err;
>>
>> +     if (prog && prog->xdp_adjust_head) {
>> +             netdev_warn(dev, "Does not support bpf_xdp_adjust_head()\n");
>> +             return -EOPNOTSUPP;
>> +     }
>> +
>>       if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
>>           virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6)) {
>>               netdev_warn(dev, "can't set XDP while host is implementing LRO, disable LRO first\n");
>>
>
> Acked-by: John Fastabend <john.r.fastabend@intel.com>
>
> Thanks patch looks good. Alternatively we could push a "bug fix" to
> support the adjust header feature depending on how DaveM and MST feel
> about that. I don't have a strong opinion but I have the patch on my
> queue it just needs some more testing.

Cool!  I thought to ask you what your plans are but then this patch is so
trivial I decided to just post it :) I'm perfectly happy with dropping it
for now and reposting after ~rc5 if needed.

Re: [PATCH net] virtio_net: reject XDP programs using header adjustment

[John Fastabend]

On 16-12-20 04:30 AM, Jakub Kicinski wrote:
> On Mon, Dec 19, 2016 at 5:50 PM, John Fastabend
> <john.fastabend@gmail.com> wrote:
>> On 16-12-19 07:05 AM, Jakub Kicinski wrote:
>>> commit 17bedab27231 ("bpf: xdp: Allow head adjustment in XDP prog")
>>> added a new XDP helper to prepend and remove data from a frame.
>>> Make virtio_net reject programs making use of this helper until
>>> proper support is added.
>>>
>>> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
>>> ---
>>>  drivers/net/virtio_net.c | 5 +++++
>>>  1 file changed, 5 insertions(+)
>>>
>>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>>> index 08327e005ccc..db761f37783e 100644
>>> --- a/drivers/net/virtio_net.c
>>> +++ b/drivers/net/virtio_net.c
>>> @@ -1677,6 +1677,11 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
>>>       u16 xdp_qp = 0, curr_qp;
>>>       int i, err;
>>>
>>> +     if (prog && prog->xdp_adjust_head) {
>>> +             netdev_warn(dev, "Does not support bpf_xdp_adjust_head()\n");
>>> +             return -EOPNOTSUPP;
>>> +     }
>>> +
>>>       if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
>>>           virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6)) {
>>>               netdev_warn(dev, "can't set XDP while host is implementing LRO, disable LRO first\n");
>>>
>>
>> Acked-by: John Fastabend <john.r.fastabend@intel.com>
>>
>> Thanks patch looks good. Alternatively we could push a "bug fix" to
>> support the adjust header feature depending on how DaveM and MST feel
>> about that. I don't have a strong opinion but I have the patch on my
>> queue it just needs some more testing.
> 
> Cool!  I thought to ask you what your plans are but then this patch is so
> trivial I decided to just post it :) I'm perfectly happy with dropping it
> for now and reposting after ~rc5 if needed.
> 

Hi Jakub,

I just posted a RFC take a look if you get a chance. Notice though Jason
fixed up my linearize path a bunch so it will need to be pushed on top
of that series.

Thanks,
John