When the MAC address is not provided by the vdpa device virtio_net driver assigns a random one without notifying the device. The consequence, in the case of mlx5_vdpa, is the internal routing tables of the device are not updated and this can block the communication between two namespaces. To fix this problem, use virtnet_send_command(VIRTIO_NET_CTRL_MAC) to set the address from virtnet_probe() when the MAC address is randomly assigned from virtio_net. While I was testing this change I found 3 other bugs in vdpa_sim_net: - vdpa_sim_net sets the VIRTIO_NET_F_MAC even if no MAC address is provided. So virtio_net doesn't generate a random MAC address and the MAC address appears to be 00:00:00:00:00:00 - vdpa_sim_net never processes the command and virtnet_send_command() hangs in an infinite loop. To avoid a kernel crash add a timeout in the loop. - To allow vdpa_sim_net to process the command, replace the cpu_relax() in the loop by a schedule(). vdpa_sim_net uses a workqueue to process the queue, and if we don't allow the kernel to schedule, the queue is not processed and the loop is infinite. Laurent Vivier (4): virtio_net: notify MAC address change on device initialization virtio_net: add a timeout in virtnet_send_command() vdpa_sim_net: don't always set VIRTIO_NET_F_MAC virtio_net: fix virtnet_send_command() with vdpa_sim_net drivers/net/virtio_net.c | 21 +++++++++++++++++++-- drivers/vdpa/vdpa_sim/vdpa_sim_net.c | 6 ++++++ 2 files changed, 25 insertions(+), 2 deletions(-) -- 2.39.0 _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
