During link announcement, driver needs a method to notify device that it has received the notification and let it clear the VIRITO_NET_S_ANNOUNCE bit in the status field. Doing this through a dedicated command looks suitable for all platforms (especially for the ones who don't trap the status read or write) with a ctrl vq and can solve the race between host and guest. So this patch makes VIRTIO_NET_F_ANNOUNCE depends on VIRTIO_NET_F_CTRL_VQ and introduces a dedicated command VIRTIO_NET_CTRL_ANNOUNCE_ACK to let device clear the VIRTIO_NET_S_ANNOUNCE bit in the status field. Changes from v1: - Send the gratuitous packets or mark them as pending before send VIRTIO_NET_CTRL_ANNOUNCE_ACK command. Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx> --- virtio-0.9.4.lyx | 76 +++++++++++++++++++++++++++++++++++++++++++++++++----- 1 files changed, 69 insertions(+), 7 deletions(-) diff --git a/virtio-0.9.4.lyx b/virtio-0.9.4.lyx index 9d30977..f376cb8 100644 --- a/virtio-0.9.4.lyx +++ b/virtio-0.9.4.lyx @@ -4013,8 +4013,12 @@ configuration layout Two configuration fields are currently defined. The mac address field always exists (though is only valid if VIRTIO_NET_F_MAC is set), and the status field only exists if VIRTIO_NET_F_STATUS is set. - Two bits are currently defined for the status field: VIRTIO_NET_S_LINK_UP - and VIRTIO_NET_S_ANNOUNCE. + Two +\change_inserted 2090695081 1332406434 +read-only +\change_unchanged +bits are currently defined for the status field: VIRTIO_NET_S_LINK_UP and + VIRTIO_NET_S_ANNOUNCE. \begin_inset listings inline false @@ -4902,18 +4906,58 @@ Gratuitous Packet Sending \end_layout \begin_layout Standard -If the driver negotiates the VIRTIO_NET_F_GUEST_ANNOUNCE, it can ask the - guest to send gratuitous packets; this is usually done after the guest - has been physically migrated, and needs to announce its presence on the - new network links. +If the driver negotiates the VIRTIO_NET_F_GUEST_ANNOUNCE +\change_inserted 2090695081 1332407810 + (depends on VIRTIO_NET_F_CTRL_VQ) +\change_unchanged +, it can ask the guest to send gratuitous packets; this is usually done + after the guest has been physically migrated, and needs to announce its + presence on the new network links. (As hypervisor does not have the knowledge of guest network configuration (eg. tagged vlan) it is simplest to prod the guest in this way). +\change_inserted 2090695081 1332405026 + +\end_layout + +\begin_layout Standard + +\change_inserted 2090695081 1332405026 +\begin_inset listings +inline false +status open + +\begin_layout Plain Layout + +\change_inserted 2090695081 1332405658 + +#define VIRTIO_NET_CTRL_ANNOUNCE 3 +\end_layout + +\begin_layout Plain Layout + +\change_inserted 2090695081 1332407582 + + #define VIRTIO_NET_CTRL_ANNOUNCE_ACK 0 +\end_layout + +\end_inset + + +\change_unchanged + \end_layout \begin_layout Standard The Guest needs to check VIRTIO_NET_S_ANNOUNCE bit in status field when it notices the changes of device configuration. + +\change_inserted 2090695081 1332407079 + The command VIRTIO_NET_CTRL_ANNOUNCE_ACK is used to indicate that driver + has recevied the notification and device would clear the VIRTIO_NET_S_ANNOUNCE + bit in the status filed after it received this command. +\change_unchanged + \end_layout \begin_layout Standard @@ -4921,11 +4965,29 @@ Processing this notification involves: \end_layout \begin_layout Enumerate + +\change_inserted 2090695081 1332471639 +Sending the gratuitous packets or marking there are pending gratuitous packets + to be sent and letting deferred routine to send them. +\end_layout + +\begin_layout Enumerate + +\change_inserted 2090695081 1332405963 +Sending VIRTIO_NET_CTRL_ANNOUNCE_ACK command through control vq. + +\change_deleted 2090695081 1332405924 Clearing VIRTIO_NET_S_ANNOUNCE bit in the status field. +\change_unchanged + \end_layout \begin_layout Enumerate -Sending the gratuitous packets. + +\change_deleted 2090695081 1332471331 +Sending the gratuitous packets +\change_unchanged +. \end_layout _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
