> -----Original Message-----
> From: Paolo Abeni <[email protected]>
> Sent: Thursday, May 22, 2025 9:44 AM
> To: Simon Horman <[email protected]>; Haiyang Zhang
> <[email protected]>
> >>>> static int mana_query_device_cfg(struct mana_context *ac, u32
> >>> proto_major_ver,
> >>>> u32 proto_minor_ver, u32
> >>>> proto_micro_ver,
> >>>> - u16 *max_num_vports)
> >>>> + u16 *max_num_vports, u8 *bm_hostmode)
> >>>> {
> >>>> struct gdma_context *gc = ac->gdma_dev->gdma_context;
> >>>> struct mana_query_device_cfg_resp resp = {};
> >>>> @@ -932,7 +932,7 @@ static int mana_query_device_cfg(struct
> mana_context
> >>> *ac, u32 proto_major_ver,
> >>>> mana_gd_init_req_hdr(&req.hdr, MANA_QUERY_DEV_CONFIG,
> >>>> sizeof(req), sizeof(resp));
> >>>>
> >>>> - req.hdr.resp.msg_version = GDMA_MESSAGE_V2;
> >>>> + req.hdr.resp.msg_version = GDMA_MESSAGE_V3;
> >>>>
> >>>> req.proto_major_ver = proto_major_ver;
> >>>> req.proto_minor_ver = proto_minor_ver;
> >>>
> >>>> @@ -956,11 +956,16 @@ static int mana_query_device_cfg(struct
> >>> mana_context *ac, u32 proto_major_ver,
> >>>>
> >>>> *max_num_vports = resp.max_num_vports;
> >>>>
> >>>> - if (resp.hdr.response.msg_version == GDMA_MESSAGE_V2)
> >>>> + if (resp.hdr.response.msg_version >= GDMA_MESSAGE_V2)
> >>>> gc->adapter_mtu = resp.adapter_mtu;
> >>>> else
> >>>> gc->adapter_mtu = ETH_FRAME_LEN;
> >>>>
> >>>> + if (resp.hdr.response.msg_version >= GDMA_MESSAGE_V3)
> >>>> + *bm_hostmode = resp.bm_hostmode;
> >>>> + else
> >>>> + *bm_hostmode = 0;
> >>>
> >>> Hi,
> >>>
> >>> Perhaps not strictly related to this patch, but I see
> >>> that mana_verify_resp_hdr() is called a few lines above.
> >>> And that verifies a minimum msg_version. But I do not see
> >>> any verification of the maximum msg_version supported by the code.
> >>>
> >>> I am concerned about a hypothetical scenario where, say the as yet
> unknown
> >>> version 5 is sent as the version, and the above behaviour is used,
> while
> >>> not being correct.
> >>>
> >>> Could you shed some light on this?
> >>>
> >>
> >> In driver, we specify the expected reply msg version is v3 here:
> >> req.hdr.resp.msg_version = GDMA_MESSAGE_V3;
> >>
> >> If the HW side is upgraded, it won't send reply msg version higher
> >> than expected, which may break the driver.
> >
> > Thanks,
> >
> > If I understand things correctly the HW side will honour the
> > req.hdr.resp.msg_version and thus the SW won't receive anything
> > it doesn't expect. Is that right?
>
> @Haiyang, if Simon's interpretation is correct, please change the
> version checking in the driver from:
>
> if (resp.hdr.response.msg_version >= GDMA_MESSAGE_V3)
>
> to
> if (resp.hdr.response.msg_version == GDMA_MESSAGE_V3)
>
> As the current code is misleading.
Simon:
Yes, you are right. So newer HW can support older driver, and vice
versa.
Paolo:
The MANA protocol doesn't remove any existing fields during upgrades.
So (resp.hdr.response.msg_version >= GDMA_MESSAGE_V3) will continue
to work in the future. If we change it to
(resp.hdr.response.msg_version == GDMA_MESSAGE_V3),
we will have to remember to update it to something like:
(resp.hdr.response.msg_version >= GDMA_MESSAGE_V3 &&
resp.hdr.response.msg_version <= GDMA_MESSAGE_V5),
if the version is upgraded to v5 in the future. And keep on updating
the checks on existing fields every time when the version is
upgraded.
So, can I keep the ">=" condition, to avoid future bug if anyone
forget to update checks on all existing fields?
Thanks,
- Haiyang
