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?
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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