netdev - Re: [PATCH net] sfc: Change VF mac via PF as first preference if available.

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Date:   Thu, 13 Oct 2022 11:09:56 +0100
From:   Edward Cree <ecree.xilinx@...il.com>
To:     Jonathan Cooper <jonathan.s.cooper@....com>,
        netdev@...r.kernel.org, linux-net-drivers@....com
Cc:     Martin Habets <habetsm.xilinx@...il.com>,
        Íñigo Huguet <ihuguet@...hat.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH net] sfc: Change VF mac via PF as first preference if
 available.

On 13/10/2022 10:55, Jonathan Cooper wrote:
> Changing a VF's mac address through the VF (rather than via the PF)
> fails with EPERM because the latter part of efx_ef10_set_mac_address
> attempts to change the vport mac address list as the VF.
> Even with this fixed it still fails with EBUSY because the vadaptor
> is still assigned on the VF - the vadaptor reassignment must be within
> a section where the VF has torn down its state.
> 
> A major reason this has broken is because we have two functions that
> ostensibly do the same thing - have a PF and VF cooperate to change a
> VF mac address. Rather than do this, if we are changing the mac of a VF
> that has a link to the PF in the same VM then simply call
> sriov_set_vf_mac instead, which is a proven working function that does
> that.
> 
> If there is no PF available, or that fails non-fatally, then attempt to
> change the VF's mac address as we would a PF, without updating the PF's
> data.
> 
> Test case:
> Create a VF:
>   echo 1 > /sys/class/net/<if>/device/sriov_numvfs
> Set the mac address of the VF directly:
>   ip link set <vf> addr 00:11:22:33:44:55
> Set the MAC address of the VF via the PF:
>   ip link set <pf> vf 0 mac 00:11:22:33:44:66
> Without this patch the last command will fail with ENOENT.
> 
> Signed-off-by: Jonathan Cooper <jonathan.s.cooper@....com>
> Reported-by: Íñigo Huguet <ihuguet@...hat.com>
> Fixes: 910c8789a777 ("set the MAC address using MC_CMD_VADAPTOR_SET_MAC")

Acked-by: Edward Cree <ecree.xilinx@...il.com>