Re: [Qemu-devel] [PATCH 2/2] qemu: add linkspeed and duplex setting to virtio-net

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Dec 19, 2017 at 11:52:39AM -0500, Jason Baron wrote:
> 
> 
> On 12/19/2017 04:19 AM, Yan Vugenfirer wrote:
> > 
> >> On 18 Dec 2017, at 18:04, Jason Baron via Qemu-devel
> >> <qemu-devel@nongnu.org <mailto:qemu-devel@nongnu.org>> wrote:
> >>
> >>
> >>
> >> On 12/18/2017 06:34 AM, Yan Vugenfirer wrote:
> >>>
> >>>> On 14 Dec 2017, at 21:33, Jason Baron via Qemu-devel
> >>>> <qemu-devel@nongnu.org <mailto:qemu-devel@nongnu.org>> wrote:
> >>>>
> >>>> Although they can be currently set in linux via 'ethtool -s', this
> >>>> requires
> >>>> guest changes, and thus it would be nice to extend this
> >>>> functionality such
> >>>> that it can be configured automatically from the host (as other network
> >>>> do).
> >>>>
> >>>> Linkspeed and duplex settings can be set as:
> >>>> '-device virtio-net,speed=10000,duplex=full'
> >>>>
> >>>> where speed is [-1...INT_MAX], and duplex is ["half"|"full"].
> >>>>
> >>>> Signed-off-by: Jason Baron <jbaron@akamai.com
> >>>> <mailto:jbaron@akamai.com>>
> >>>> Cc: "Michael S. Tsirkin" <mst@redhat.com <mailto:mst@redhat.com>>
> >>>> Cc: Jason Wang <jasowang@redhat.com <mailto:jasowang@redhat.com>>
> >>>> ---
> >>>> hw/net/virtio-net.c                         | 29
> >>>> +++++++++++++++++++++++++++++
> >>>> include/hw/virtio/virtio-net.h              |  3 +++
> >>>> include/standard-headers/linux/virtio_net.h |  4 ++++
> >>>> 3 files changed, 36 insertions(+)
> >>>>
> >>>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> >>>> index 38674b0..d63e790 100644
> >>>> --- a/hw/net/virtio-net.c
> >>>> +++ b/hw/net/virtio-net.c
> >>>> @@ -40,6 +40,12 @@
> >>>> #define VIRTIO_NET_RX_QUEUE_MIN_SIZE VIRTIO_NET_RX_QUEUE_DEFAULT_SIZE
> >>>> #define VIRTIO_NET_TX_QUEUE_MIN_SIZE VIRTIO_NET_TX_QUEUE_DEFAULT_SIZE
> >>>>
> >>>> +/* duplex and speed defines */
> >>>> +#define DUPLEX_UNKNOWN          0xff
> >>>> +#define DUPLEX_HALF             0x00
> >>>> +#define DUPLEX_FULL             0x01
> >>>> +#define SPEED_UNKNOWN           -1
> >>>> +
> >>>> /*
> >>>> * Calculate the number of bytes up to and including the given 'field' of
> >>>> * 'container'.
> >>>> @@ -61,6 +67,8 @@ static VirtIOFeature feature_sizes[] = {
> >>>>     .end = endof(struct virtio_net_config, max_virtqueue_pairs)},
> >>>>    {.flags = 1 << VIRTIO_NET_F_MTU,
> >>>>     .end = endof(struct virtio_net_config, mtu)},
> >>>> +    {.flags = 1 << VIRTIO_NET_F_SPEED_DUPLEX,
> >>>> +     .end = endof(struct virtio_net_config, duplex)},
> >>>>    {}
> >>>> };
> >>>>
> >>>> @@ -88,6 +96,8 @@ static void virtio_net_get_config(VirtIODevice
> >>>> *vdev, uint8_t *config)
> >>>>    virtio_stw_p(vdev, &netcfg.status, n->status);
> >>>>    virtio_stw_p(vdev, &netcfg.max_virtqueue_pairs, n->max_queues);
> >>>>    virtio_stw_p(vdev, &netcfg.mtu, n->net_conf.mtu);
> >>>> +    virtio_stl_p(vdev, &netcfg.speed, n->net_conf.speed);
> >>>> +    netcfg.duplex = n->net_conf.duplex;
> >>>>    memcpy(netcfg.mac, n->mac, ETH_ALEN);
> >>>>    memcpy(config, &netcfg, n->config_size);
> >>>> }
> >>>> @@ -1941,6 +1951,23 @@ static void
> >>>> virtio_net_device_realize(DeviceState *dev, Error **errp)
> >>>>        n->host_features |= (0x1 << VIRTIO_NET_F_MTU);
> >>>>    }
> >>>>
> >>>> +    n->host_features |= (0x1 << VIRTIO_NET_F_SPEED_DUPLEX);
> >>>> +    if (n->net_conf.duplex_str) {
> >>>> +        if (strncmp(n->net_conf.duplex_str, "half", 5) == 0) {
> >>>> +            n->net_conf.duplex = DUPLEX_HALF;
> >>>> +        } else if (strncmp(n->net_conf.duplex_str, "full", 5) == 0) {
> >>>> +            n->net_conf.duplex = DUPLEX_FULL;
> >>>> +        } else {
> >>>> +            error_setg(errp, "'duplex' must be 'half' or 'full'");
> >>>> +        }
> >>>> +    } else {
> >>>> +        n->net_conf.duplex = DUPLEX_UNKNOWN;
> >>>> +    }
> >>>> +    if (n->net_conf.speed < SPEED_UNKNOWN) {
> >>>> +            error_setg(errp, "'speed' must be between -1
> >>>> (SPEED_UNKOWN) and "
> >>>> +                       "INT_MAX");
> >>>> +    }
> >>>> +
> >>>>    virtio_net_set_config_size(n, n->host_features);
> >>>>    virtio_init(vdev, "virtio-net", VIRTIO_ID_NET, n->config_size);
> >>>>
> >>>> @@ -2160,6 +2187,8 @@ static Property virtio_net_properties[] = {
> >>>>    DEFINE_PROP_UINT16("host_mtu", VirtIONet, net_conf.mtu, 0),
> >>>>    DEFINE_PROP_BOOL("x-mtu-bypass-backend", VirtIONet,
> >>>> mtu_bypass_backend,
> >>>>                     true),
> >>>> +    DEFINE_PROP_INT32("speed", VirtIONet, net_conf.speed,
> >>>> SPEED_UNKNOWN),
> >>>
> >>> From Windows guest perspective I prefer to have some reasonable
> >>> default (10G for example). 
> >>
> >>
> >> hmmm, I didn't want to change/set the default here in case it broke
> >> something, but I'm ok setting it to some 'reasonable' value - (10G and
> >> duplex?), if the consensus is that that would be safe.
> > 
> > OK from my side.
> > Thanks.
> 
> I presume your speaking for windows - i'm wondering if under linux the
> virtio device suddenly start showing up as duplex, 10Gbps, will that
> break anything? I can speak for the use-cases we have here and that
> would certainly be fine for us, but i'm really not sure if that is ok
> more generally.
> 
> Thanks,
> 
> -Jason

How about not enabling the flag unless the user specified the speed?
This way we also do not need an "unknown" value.

> > 
> >>
> >> Thanks,
> >>
> >> -Jason
> >>
> >>>
> >>> Thanks,
> >>> Yan.
> >>>
> >>>> +    DEFINE_PROP_STRING("duplex", VirtIONet, net_conf.duplex_str),
> >>>>    DEFINE_PROP_END_OF_LIST(),
> >>>> };
> >>>>
> >>>> diff --git a/include/hw/virtio/virtio-net.h
> >>>> b/include/hw/virtio/virtio-net.h
> >>>> index b81b6a4..af74a94 100644
> >>>> --- a/include/hw/virtio/virtio-net.h
> >>>> +++ b/include/hw/virtio/virtio-net.h
> >>>> @@ -38,6 +38,9 @@ typedef struct virtio_net_conf
> >>>>    uint16_t rx_queue_size;
> >>>>    uint16_t tx_queue_size;
> >>>>    uint16_t mtu;
> >>>> +    int32_t speed;
> >>>> +    char *duplex_str;
> >>>> +    uint8_t duplex;
> >>>> } virtio_net_conf;
> >>>>
> >>>> /* Maximum packet size we can receive from tap device: header + 64k */
> >>>> diff --git a/include/standard-headers/linux/virtio_net.h
> >>>> b/include/standard-headers/linux/virtio_net.h
> >>>> index 30ff249..0ff1447 100644
> >>>> --- a/include/standard-headers/linux/virtio_net.h
> >>>> +++ b/include/standard-headers/linux/virtio_net.h
> >>>> @@ -36,6 +36,7 @@
> >>>> #define VIRTIO_NET_F_GUEST_CSUM1/* Guest handles pkts w/ partial csum */
> >>>> #define VIRTIO_NET_F_CTRL_GUEST_OFFLOADS 2 /* Dynamic offload
> >>>> configuration. */
> >>>> #define VIRTIO_NET_F_MTU3/* Initial MTU advice */
> >>>> +#define VIRTIO_NET_F_SPEED_DUPLEX 4/* Host set linkspeed and duplex */
> >>>> #define VIRTIO_NET_F_MAC5/* Host has given MAC address. */
> >>>> #define VIRTIO_NET_F_GUEST_TSO47/* Guest can handle TSOv4 in. */
> >>>> #define VIRTIO_NET_F_GUEST_TSO68/* Guest can handle TSOv6 in. */
> >>>> @@ -76,6 +77,9 @@ struct virtio_net_config {
> >>>> uint16_t max_virtqueue_pairs;
> >>>> /* Default maximum transmit unit advice */
> >>>> uint16_t mtu;
> >>>> +/* Host exported linkspeed and duplex */
> >>>> +uint32_t speed;
> >>>> +uint8_t duplex;
> >>>> } QEMU_PACKED;
> >>>>
> >>>> /*
> >>>> -- 
> >>>> 2.6.1
> >