netdev - Re: [PATCH net-next 4/4] bnxt_en: Always forward VF MAC address to the PF.

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Date:   Fri, 14 Sep 2018 05:49:02 -0700
From:   Siwei Liu <loseweigh@...il.com>
To:     Michael Chan <michael.chan@...adcom.com>
Cc:     David Miller <davem@...emloft.net>,
        Netdev <netdev@...r.kernel.org>,
        si-wei liu <si-wei.liu@...cle.com>
Subject: Re: [PATCH net-next 4/4] bnxt_en: Always forward VF MAC address to
 the PF.

This commit is toxic, if possible I hope it can be reverted and
reworked with a new patch.

First, the patch introduced backward incompatible changes to bnxt_en
VF driver that is causing issue when interoperating with the old PF
driver without this commit. In that event, VF probing fails from
within the VM:

[    5.660331] Broadcom NetXtreme-C/E driver bnxt_en v1.9.1
[    5.663653] bnxt_en 0000:00:03.0 (unnamed net_device)
(uninitialized): hwrm req_type 0xf seq id 0x6 error 0x4
[    5.665804] bnxt_en 0000:00:03.0 (unnamed net_device)
(uninitialized): VF MAC address 00:01:02:03:04:05 not approved by the
PF
[    5.668268] bnxt_en 0000:00:03.0: Unable to initialize mac address.
[    5.670974] bnxt_en: probe of 0000:00:03.0 failed with error -99

Second, this commit contains driver changes to both PF and VF side,
and incorrectly assumes that both PF and VF can/should be updated at
the same time to resolve the original issue (zero VF MAC address in
'ip link show') it tried to address. In fact that is not warranted. A
potential warranted fix is for VF driver to ignore what
bnxt_approve_mac() may return when it got a valid MAC address from the
firmware. The only purpose for the bnxt_approve_mac call for this case
is a best-effort attempt to inform PF of the MAC address, instead of
failing the VF driver probe when talking to an old PF driver.

Canonical reported a similar issue a few days back due to the same cause.

https://www.spinics.net/lists/netdev/msg521428.html


Regards,
-Siwei

On Tue, May 8, 2018 at 12:18 AM, Michael Chan <michael.chan@...adcom.com> wrote:
> The current code already forwards the VF MAC address to the PF, except
> in one case.  If the VF driver gets a valid MAC address from the firmware
> during probe time, it will not forward the MAC address to the PF,
> incorrectly assuming that the PF already knows the MAC address.  This
> causes "ip link show" to show zero VF MAC addresses for this case.
>
> This assumption is not correct.  Newer firmware remembers the VF MAC
> address last used by the VF and provides it to the VF driver during
> probe.  So we need to always forward the VF MAC address to the PF.
>
> The forwarded MAC address may now be the PF assigned MAC address and so we
> need to make sure we approve it for this case.
>
> Signed-off-by: Michael Chan <michael.chan@...adcom.com>
> ---
>  drivers/net/ethernet/broadcom/bnxt/bnxt.c       | 2 +-
>  drivers/net/ethernet/broadcom/bnxt/bnxt_sriov.c | 3 ++-
>  2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> index cd3ab78..dfa0839 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> @@ -8678,8 +8678,8 @@ static int bnxt_init_mac_addr(struct bnxt *bp)
>                         memcpy(bp->dev->dev_addr, vf->mac_addr, ETH_ALEN);
>                 } else {
>                         eth_hw_addr_random(bp->dev);
> -                       rc = bnxt_approve_mac(bp, bp->dev->dev_addr);
>                 }
> +               rc = bnxt_approve_mac(bp, bp->dev->dev_addr);
>  #endif
>         }
>         return rc;
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_sriov.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_sriov.c
> index cc21d87..a649108 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt_sriov.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_sriov.c
> @@ -923,7 +923,8 @@ static int bnxt_vf_configure_mac(struct bnxt *bp, struct bnxt_vf_info *vf)
>         if (req->enables & cpu_to_le32(FUNC_VF_CFG_REQ_ENABLES_DFLT_MAC_ADDR)) {
>                 if (is_valid_ether_addr(req->dflt_mac_addr) &&
>                     ((vf->flags & BNXT_VF_TRUST) ||
> -                    (!is_valid_ether_addr(vf->mac_addr)))) {
> +                    !is_valid_ether_addr(vf->mac_addr) ||
> +                    ether_addr_equal(req->dflt_mac_addr, vf->mac_addr))) {
>                         ether_addr_copy(vf->vf_mac_addr, req->dflt_mac_addr);
>                         return bnxt_hwrm_exec_fwd_resp(bp, vf, msg_size);
>                 }
> --
> 1.8.3.1
>