On 28.08.24 11:00, Cindy Lu wrote: > On Wed, 28 Aug 2024 at 09:51, Jason Wang <jasowang@xxxxxxxxxx> wrote: >> >> On Wed, Aug 28, 2024 at 12:03 AM Dragos Tatulea <dtatulea@xxxxxxxxxx> wrote: >>> >>> When the vdpa device is configured without a specific MAC >>> address, the vport MAC address is used. However, this >>> address can be 0 which prevents the driver from properly >>> configuring the MPFS and breaks steering. >>> >>> The solution is to simply generate a random MAC address >>> when no MAC is set on the nic vport. >>> >>> Now it's possible to create a vdpa device without a >>> MAC address and run qemu with this device without needing >>> to configure an explicit MAC address. >>> >>> Signed-off-by: Dragos Tatulea <dtatulea@xxxxxxxxxx> >>> Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxx> >> >> Acked-by: Jason Wang <jasowang@xxxxxxxxxx> >> >> (Adding Cindy for double checking if it has any side effect on Qemu side) >> >> Thanks >> > But Now there is a bug in QEMU: if the hardware MAC address does not > match the one in the QEMU command line, it will cause traffic loss. > Why is this a new issue in qemu? qemu in it's current state won't work with a different mac address that the one that is set in HW anyway. > So, Just an FYI here: if your patch merged, it may cause traffic loss. > and now I'm working in the fix it in qemu, the link is > https://patchew.org/QEMU/20240716011349.821777-1-lulu@xxxxxxxxxx/ > The idea of this fix is > There are will only two acceptable situations for qemu: > 1. The hardware MAC address is the same as the MAC address specified > in the QEMU command line, and both MAC addresses are not 0. > 2. The hardware MAC address is not 0, and the MAC address in the QEMU > command line is 0. In this situation, the hardware MAC address will > overwrite the QEMU command line address. > Why would this not work with this patch? This patch simply sets a MAC if the vport doesn't have one set. Which allows for more scenarios to work. Thanks, Dragos > Thanks > Cindy > > >>> --- >>> drivers/vdpa/mlx5/net/mlx5_vnet.c | 3 +++ >>> 1 file changed, 3 insertions(+) >>> >>> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c >>> index fa78e8288ebb..1c26139d02fe 100644 >>> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c >>> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c >>> @@ -3824,6 +3824,9 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name, >>> err = mlx5_query_nic_vport_mac_address(mdev, 0, 0, config->mac); >>> if (err) >>> goto err_alloc; >>> + >>> + if (is_zero_ether_addr(config->mac)) >>> + eth_random_addr(config->mac); >>> } >>> >>> if (!is_zero_ether_addr(config->mac)) { >>> -- >>> 2.45.1 >>> >> >
