In virtnet_probe(), if the device doesn't provide a MAC address the
driver assigns a random one.
As we modify the MAC address we need to notify the device to allow it
to update all the related information.
The problem can be seen with vDPA and mlx5_vdpa driver as it doesn't
assign a MAC address by default. The virtio_net device uses a random
MAC address (we can see it with "ip link"), but we can't ping a net
namespace from another one using the virtio-vdpa device because the
new MAC address has not been provided to the hardware.
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
drivers/net/virtio_net.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 7723b2a49d8e..25511a86590e 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3800,6 +3800,8 @@ static int virtnet_probe(struct virtio_device *vdev)
eth_hw_addr_set(dev, addr);
} else {
eth_hw_addr_random(dev);
+ dev_info(&vdev->dev, "Assigned random MAC address %pM\n",
+ dev->dev_addr);
}
/* Set up our device-specific information */
@@ -3956,6 +3958,18 @@ static int virtnet_probe(struct virtio_device *vdev)
pr_debug("virtnet: registered device %s with %d RX and TX vq's\n",
dev->name, max_queue_pairs);
+ /* a random MAC address has been assigned, notify the device */
+ if (dev->addr_assign_type == NET_ADDR_RANDOM &&
+ virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)) {
+ struct scatterlist sg;
+
+ sg_init_one(&sg, dev->dev_addr, dev->addr_len);
+ if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
+ VIRTIO_NET_CTRL_MAC_ADDR_SET, &sg)) {
+ dev_warn(&vdev->dev, "Failed to update MAC address.\n");
+ }
+ }
+
return 0;
free_unregister_netdev:
--
2.39.0
On 22/01/2023 12:05, Laurent Vivier wrote:
> In virtnet_probe(), if the device doesn't provide a MAC address the
> driver assigns a random one.
> As we modify the MAC address we need to notify the device to allow it
> to update all the related information.
>
> The problem can be seen with vDPA and mlx5_vdpa driver as it doesn't
> assign a MAC address by default. The virtio_net device uses a random
> MAC address (we can see it with "ip link"), but we can't ping a net
> namespace from another one using the virtio-vdpa device because the
> new MAC address has not been provided to the hardware.
>
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
> drivers/net/virtio_net.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7723b2a49d8e..25511a86590e 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -3800,6 +3800,8 @@ static int virtnet_probe(struct virtio_device *vdev)
> eth_hw_addr_set(dev, addr);
> } else {
> eth_hw_addr_random(dev);
> + dev_info(&vdev->dev, "Assigned random MAC address %pM\n",
> + dev->dev_addr);
> }
>
> /* Set up our device-specific information */
> @@ -3956,6 +3958,18 @@ static int virtnet_probe(struct virtio_device *vdev)
> pr_debug("virtnet: registered device %s with %d RX and TX vq's\n",
> dev->name, max_queue_pairs);
>
> + /* a random MAC address has been assigned, notify the device */
> + if (dev->addr_assign_type == NET_ADDR_RANDOM &&
Maybe it's better to not count on addr_assign_type and use a local
variable to indicate that virtnet_probe assigned random MAC. The reason
is that the hardware driver might have done that as well and does not
need notification.
> + virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)) {
> + struct scatterlist sg;
> +
> + sg_init_one(&sg, dev->dev_addr, dev->addr_len);
> + if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
> + VIRTIO_NET_CTRL_MAC_ADDR_SET, &sg)) {
> + dev_warn(&vdev->dev, "Failed to update MAC address.\n");
> + }
> + }
> +
> return 0;
>
> free_unregister_netdev:
On Sun, 22 Jan 2023 15:47:08 +0200 Eli Cohen wrote:
> > @@ -3956,6 +3958,18 @@ static int virtnet_probe(struct virtio_device *vdev)
> > pr_debug("virtnet: registered device %s with %d RX and TX vq's\n",
> > dev->name, max_queue_pairs);
> >
> > + /* a random MAC address has been assigned, notify the device */
> > + if (dev->addr_assign_type == NET_ADDR_RANDOM &&
> Maybe it's better to not count on addr_assign_type and use a local
> variable to indicate that virtnet_probe assigned random MAC.
+1, FWIW
On 1/24/23 04:31, Jakub Kicinski wrote:
> On Sun, 22 Jan 2023 15:47:08 +0200 Eli Cohen wrote:
>>> @@ -3956,6 +3958,18 @@ static int virtnet_probe(struct virtio_device *vdev)
>>> pr_debug("virtnet: registered device %s with %d RX and TX vq's\n",
>>> dev->name, max_queue_pairs);
>>>
>>> + /* a random MAC address has been assigned, notify the device */
>>> + if (dev->addr_assign_type == NET_ADDR_RANDOM &&
>> Maybe it's better to not count on addr_assign_type and use a local
>> variable to indicate that virtnet_probe assigned random MAC.
>
> +1, FWIW
>
v2 sent, but I rely on virtio_has_feature(vdev, VIRTIO_NET_F_MAC) to know if the MAC
address is provided by the device or not:
https://lore.kernel.org/lkml/20230123120022.2364889-2-lvivier@redhat.com/T/#me9211516e12771001e0346818255c9fb48a2bf4a
Thanks,
Laurent
On 1/22/23 14:47, Eli Cohen wrote:
>
> On 22/01/2023 12:05, Laurent Vivier wrote:
>> In virtnet_probe(), if the device doesn't provide a MAC address the
>> driver assigns a random one.
>> As we modify the MAC address we need to notify the device to allow it
>> to update all the related information.
>>
>> The problem can be seen with vDPA and mlx5_vdpa driver as it doesn't
>> assign a MAC address by default. The virtio_net device uses a random
>> MAC address (we can see it with "ip link"), but we can't ping a net
>> namespace from another one using the virtio-vdpa device because the
>> new MAC address has not been provided to the hardware.
>>
>> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
>> ---
>> drivers/net/virtio_net.c | 14 ++++++++++++++
>> 1 file changed, 14 insertions(+)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 7723b2a49d8e..25511a86590e 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -3800,6 +3800,8 @@ static int virtnet_probe(struct virtio_device *vdev)
>> eth_hw_addr_set(dev, addr);
>> } else {
>> eth_hw_addr_random(dev);
>> + dev_info(&vdev->dev, "Assigned random MAC address %pM\n",
>> + dev->dev_addr);
>> }
>> /* Set up our device-specific information */
>> @@ -3956,6 +3958,18 @@ static int virtnet_probe(struct virtio_device *vdev)
>> pr_debug("virtnet: registered device %s with %d RX and TX vq's\n",
>> dev->name, max_queue_pairs);
>> + /* a random MAC address has been assigned, notify the device */
>> + if (dev->addr_assign_type == NET_ADDR_RANDOM &&
> Maybe it's better to not count on addr_assign_type and use a local variable to indicate
> that virtnet_probe assigned random MAC. The reason is that the hardware driver might have
> done that as well and does not need notification.
eth_hw_addr_random() sets explicitly NET_ADDR_RANDOM, while eth_hw_addr_set() doesn't
change addr_assign_type so it doesn't seem this value is set by the hardware driver.
So I guess it's the default value (NET_ADDR_PERM) in this case (even if it's a random
address from the point of view of the hardware).
If you prefer I can replace it by "!virtio_has_feature(vdev, VIRTIO_NET_F_MAC)"?
Thanks,
Laurent
On 23/01/2023 11:52, Laurent Vivier wrote:
> On 1/22/23 14:47, Eli Cohen wrote:
>>
>> On 22/01/2023 12:05, Laurent Vivier wrote:
>>> In virtnet_probe(), if the device doesn't provide a MAC address the
>>> driver assigns a random one.
>>> As we modify the MAC address we need to notify the device to allow it
>>> to update all the related information.
>>>
>>> The problem can be seen with vDPA and mlx5_vdpa driver as it doesn't
>>> assign a MAC address by default. The virtio_net device uses a random
>>> MAC address (we can see it with "ip link"), but we can't ping a net
>>> namespace from another one using the virtio-vdpa device because the
>>> new MAC address has not been provided to the hardware.
>>>
>>> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
>>> ---
>>> drivers/net/virtio_net.c | 14 ++++++++++++++
>>> 1 file changed, 14 insertions(+)
>>>
>>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>>> index 7723b2a49d8e..25511a86590e 100644
>>> --- a/drivers/net/virtio_net.c
>>> +++ b/drivers/net/virtio_net.c
>>> @@ -3800,6 +3800,8 @@ static int virtnet_probe(struct virtio_device
>>> *vdev)
>>> eth_hw_addr_set(dev, addr);
>>> } else {
>>> eth_hw_addr_random(dev);
>>> + dev_info(&vdev->dev, "Assigned random MAC address %pM\n",
>>> + dev->dev_addr);
>>> }
>>> /* Set up our device-specific information */
>>> @@ -3956,6 +3958,18 @@ static int virtnet_probe(struct virtio_device
>>> *vdev)
>>> pr_debug("virtnet: registered device %s with %d RX and TX
>>> vq's\n",
>>> dev->name, max_queue_pairs);
>>> + /* a random MAC address has been assigned, notify the device */
>>> + if (dev->addr_assign_type == NET_ADDR_RANDOM &&
>> Maybe it's better to not count on addr_assign_type and use a local
>> variable to indicate that virtnet_probe assigned random MAC. The
>> reason is that the hardware driver might have done that as well and
>> does not need notification.
>
> eth_hw_addr_random() sets explicitly NET_ADDR_RANDOM, while
> eth_hw_addr_set() doesn't change addr_assign_type so it doesn't seem
> this value is set by the hardware driver.
>
> So I guess it's the default value (NET_ADDR_PERM) in this case (even
> if it's a random address from the point of view of the hardware).
>
> If you prefer I can replace it by "!virtio_has_feature(vdev,
> VIRTIO_NET_F_MAC)"?
>
My point is this. What if the hardware driver decides to choose a random
address by calling eth_hw_addr_random(). In this case
dev->addr_assign_type = NET_ADDR_RANDOM is executed unconditionally. But
now you will needlessly execute the control command because the hardware
address already knows about this address.
> Thanks,
> Laurent
>
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