On 01/04/2018 01:22 PM, Michael S. Tsirkin wrote:
> On Thu, Jan 04, 2018 at 01:12:30PM -0500, Jason Baron wrote:
>>
>>
>> On 01/04/2018 12:05 PM, Michael S. Tsirkin wrote:
>>> On Thu, Jan 04, 2018 at 12:16:44AM -0500, Jason Baron wrote:
>>>> The ability to set speed and duplex for virtio_net is useful in various
>>>> scenarios as described here:
>>>>
>>>> 16032be virtio_net: add ethtool support for set and get of settings
>>>>
>>>> However, it would be nice to be able to set this from the hypervisor,
>>>> such that virtio_net doesn't require custom guest ethtool commands.
>>>>
>>>> Introduce a new feature flag, VIRTIO_NET_F_SPEED_DUPLEX, which allows
>>>> the hypervisor to export a linkspeed and duplex setting. The user can
>>>> subsequently overwrite it later if desired via: 'ethtool -s'.
>>>>
>>>> Note that VIRTIO_NET_F_SPEED_DUPLEX is defined as bit 63, the intention
>>>> is that device feature bits are to grow down from bit 63, since the
>>>> transports are starting from bit 24 and growing up.
>>>>
>>>> Signed-off-by: Jason Baron <jbaron@xxxxxxxxxx>
>>>> Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
>>>> Cc: Jason Wang <jasowang@xxxxxxxxxx>
>>>> Cc: virtio-dev@xxxxxxxxxxxxxxxxxxxx
>>>> ---
>>>> drivers/net/virtio_net.c | 19 ++++++++++++++++++-
>>>> include/uapi/linux/virtio_net.h | 13 +++++++++++++
>>>> 2 files changed, 31 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>>>> index 6fb7b65..0b2d314 100644
>>>> --- a/drivers/net/virtio_net.c
>>>> +++ b/drivers/net/virtio_net.c
>>>> @@ -2146,6 +2146,22 @@ static void virtnet_config_changed_work(struct work_struct *work)
>>>>
>>>> vi->status = v;
>>>>
>>>> + if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_SPEED_DUPLEX)) {
>>>
>>> BTW we can avoid this read for when link goes down.
>>> Not a big deal but still.
>>
>> So you are saying that we can just set vi->speed and vi->duplex to
>> 'unknown' when the link goes down and not check for the presence of
>> VIRTIO_NET_F_SPEED_DUPLEX?
>>
>> If so, that could over-write what the user may have configured in the
>> guest via 'ethtool -s' when the link goes down, so that would be a
>> change in behavior, but perhaps that is ok?
>
> No - what I am saying is that your patch overwrites the values
> set by user when link goes down.
>
> I suggest limiting this call to when
>
> if (vi->status & VIRTIO_NET_S_LINK_UP)
>
> and then the values are overwritten when link goes up
> which seems closer to what a user might expect.
ok, will update this for v4.
Thanks,
-Jason
>
>>
>> I think I would prefer to have the link down event still check for
>> VIRTIO_NET_F_SPEED_DUPLEX before changing speed/duplex. That way we
>> still have 2 modes for updating the fields:
>>
>> 1) completely guest controlled. Same as we have now and host does not
>> change any values and does not set VIRTIO_NET_F_SPEED_DUPLEX flag (hence
>> don't remove above check).
>>
>> 2) if speed or duplex or speed is set in the qemu command line, then set
>> the VIRTIO_NET_F_SPEED_DUPLEX and have host control the settings of
>> speed/duplex (with ability of guest to over-write if it wanted to).
>>
>>
>>>
>>>> + u32 speed;
>>>> + u8 duplex;
>>>> +
>>>> + speed = virtio_cread32(vi->vdev,
>>>> + offsetof(struct virtio_net_config,
>>>> + speed));
>>>> + if (ethtool_validate_speed(speed))
>>>> + vi->speed = speed;
>>>> + duplex = virtio_cread8(vi->vdev,
>>>> + offsetof(struct virtio_net_config,
>>>> + duplex));
>>>> + if (ethtool_validate_duplex(duplex))
>>>> + vi->duplex = duplex;
>>>> + }
>>>> +
>>>> if (vi->status & VIRTIO_NET_S_LINK_UP) {
>>>> netif_carrier_on(vi->dev);
>>>> netif_tx_wake_all_queues(vi->dev);
>>>
>>> OK so this handles the case when VIRTIO_NET_F_STATUS is set,
>>> but when it's clear we need to call this from virtnet_probe.
>>>
>>> I propose moving this chunk to a function and calling from two places.
>>>
>>
>> good point. will update.
>>
>> Thanks,
>>
>> -Jason
>>
>>>
>>>> @@ -2796,7 +2812,8 @@ static struct virtio_device_id id_table[] = {
>>>> VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN, \
>>>> VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, \
>>>> VIRTIO_NET_F_CTRL_MAC_ADDR, \
>>>> - VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS
>>>> + VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
>>>> + VIRTIO_NET_F_SPEED_DUPLEX
>>>>
>>>> static unsigned int features[] = {
>>>> VIRTNET_FEATURES,
>>>> diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
>>>> index fc353b5..5de6ed3 100644
>>>> --- a/include/uapi/linux/virtio_net.h
>>>> +++ b/include/uapi/linux/virtio_net.h
>>>> @@ -57,6 +57,8 @@
>>>> * Steering */
>>>> #define VIRTIO_NET_F_CTRL_MAC_ADDR 23 /* Set MAC address */
>>>>
>>>> +#define VIRTIO_NET_F_SPEED_DUPLEX 63 /* Device set linkspeed and duplex */
>>>> +
>>>> #ifndef VIRTIO_NET_NO_LEGACY
>>>> #define VIRTIO_NET_F_GSO 6 /* Host handles pkts w/ any GSO type */
>>>> #endif /* VIRTIO_NET_NO_LEGACY */
>>>> @@ -76,6 +78,17 @@ struct virtio_net_config {
>>>> __u16 max_virtqueue_pairs;
>>>> /* Default maximum transmit unit advice */
>>>> __u16 mtu;
>>>> + /*
>>>> + * speed, in units of 1Mb. All values 0 to INT_MAX are legal.
>>>> + * Any other value stands for unknown.
>>>> + */
>>>> + __u32 speed;
>>>> + /*
>>>> + * 0x00 - half duplex
>>>> + * 0x01 - full duplex
>>>> + * Any other value stands for unknown.
>>>> + */
>>>> + __u8 duplex;
>>>> } __attribute__((packed));
>>>>
>>>> /*
>>>> --
>>>> 2.6.1
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