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From:   Laurent Vivier <lvivier@redhat.com>
To:     linux-kernel@vger.kernel.org
Cc:     "Michael S. Tsirkin" <mst@redhat.com>,
        Parav Pandit <parav@nvidia.com>,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
        Eli Cohen <elic@nvidia.com>, Jason Wang <jasowang@redhat.com>,
        Gautam Dawar <gautam.dawar@xilinx.com>,
        Cindy Lu <lulu@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        =?UTF-8?q?Eugenio=20P=C3=A9rez?= <eperezma@redhat.com>
Subject: [PATCH 0/4] virtio_net: vdpa: update MAC address when it is generated by virtio-net
Date:   Sun, 22 Jan 2023 11:05:22 +0100
Message-Id: <20230122100526.2302556-1-lvivier@redhat.com>
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Precedence: bulk

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